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Sample records for rutheniumii arene complexes

  1. Binding of mismatch repair protein MutS to mispaired DNA adducts of intercalating ruthenium(II) arene complexes.

    PubMed

    Castellano-Castillo, Maria; Kostrhunova, Hana; Marini, Victoria; Kasparkova, Jana; Sadler, Peter J; Malinge, Jean-Marc; Brabec, Viktor

    2008-08-01

    The present study was performed to examine the affinity of Escherichia coli mismatch repair (MMR) protein MutS for DNA damaged by an intercalating compound. We examined the binding properties of this protein with various DNA substrates containing a single centrally located adduct of ruthenium(II) arene complexes [(eta(6)-arene)Ru(II)(en)Cl][PF(6)] [arene is tetrahydroanthracene (THA) or p-cymene (CYM); en is ethylenediamine]. These two complexes were chosen as representatives of two different classes of monofunctional ruthenium(II) arene compounds which differ in DNA-binding modes: one that involves combined coordination to G N7 along with noncovalent, hydrophobic interactions, such as partial arene intercalation (tricyclic-ring Ru-THA), and the other that binds to DNA only via coordination to G N7 and does not interact with double-helical DNA by intercalation (monoring Ru-CYM). Using electrophoretic mobility shift assays, we examined the binding properties of MutS protein with various DNA duplexes (homoduplexes or mismatched duplexes) containing a single centrally located adduct of ruthenium(II) arene compounds. We have shown that presence of the ruthenium(II) arene adducts decreases the affinity of MutS for ruthenated DNA duplexes that either have a regular sequence or contain a mismatch and that intercalation of the arene contributes considerably to this inhibitory effect. Since MutS initiates MMR by recognizing DNA lesions, the results of the present work support the view that DNA damage due to intercalation is removed from DNA by a mechanism(s) other than MMR.

  2. The contrasting chemistry and cancer cell cytotoxicity of bipyridine and bipyridinediol ruthenium(II) arene complexes.

    PubMed

    Bugarcic, Tijana; Habtemariam, Abraha; Stepankova, Jana; Heringova, Pavla; Kasparkova, Jana; Deeth, Robert J; Johnstone, Russell D L; Prescimone, Alessandro; Parkin, Andrew; Parsons, Simon; Brabec, Viktor; Sadler, Peter J

    2008-12-15

    The synthesis and characterization of ruthenium(II) arene complexes [(eta(6)-arene)Ru(N,N)Cl](0/+), where N,N = 2,2'-bipyridine (bipy), 2,2'-bipyridine-3,3'-diol (bipy(OH)(2)) or deprotonated 2,2'-bipyridine-3,3'-diol (bipy(OH)O) as N,N-chelating ligand, arene = benzene (bz), indan (ind), biphenyl (bip), p-terphenyl (p-terp), tetrahydronaphthalene (thn), tetrahydroanthracene (tha) or dihydroanthracene (dha), are reported, including the X-ray crystal structures of [(eta(6)-tha)Ru(bipy)Cl][PF(6)] (1), [(eta(6)-tha)Ru(bipy(OH)O)Cl] (2) and [(eta(6)-ind)Ru(bipy(OH)(2))Cl][PF(6)] (8). Complexes 1 and 2 exibit CH (arene)/pi (bipy or bipy(OH)O) interactions. In the X-ray structure of protonated complex 8, the pyridine rings are twisted (by 17.31 degrees). In aqueous solution (pH = 2-10), only deprotonated (bipy(OH)O) forms are present. Hydrolysis of the complexes was relatively fast in aqueous solution (t(1/2) = 4-15 min, 310 K). When the arene is biphenyl, initial aquation of the complexes is followed by partial arene loss. Complexes with arene = tha, thn, dha, ind and p-terp, and deprotonated bipyridinediol (bipy(OH)O) as chelating ligands, exhibited significant cytotoxicity toward A2780 human ovarian and A549 human lung cancer cells. Complexes [(eta(6)-bip)Ru(bipy(OH)O)Cl] (7) and [(eta(6)-bz)Ru(bipy(OH)O)Cl] (5) exhibited moderate cytotoxicity toward A2780 cells, but were inactive toward A549 cells. These activity data can be contrasted with those of the parent bipyridine complex [(eta(6)-tha)Ru(bipy)Cl][PF(6)] (1) which is inactive toward both A2780 ovarian and A549 lung cell lines. DFT calculations suggested that hydroxylation and methylation of the bipy ligand have little effect on the charge on Ru. The active complex [(eta(6)-tha)Ru(bipy(OH)O)Cl] (2) binds strongly to 9-ethyl-guanine (9-EtG). The X-ray crystal structure of the adduct [(eta(6)-tha)Ru(bipy(OH)O)(9-EtG-N7)][PF(6)] shows intramolecular CH (arene)/pi (bipy(OH)O) interactions and DFT calculations

  3. Derivation of structure-activity relationships from the anticancer properties of ruthenium(II) arene complexes with 2-aryldiazole ligands.

    PubMed

    Martínez-Alonso, Marta; Busto, Natalia; Jalón, Félix A; Manzano, Blanca R; Leal, José M; Rodríguez, Ana M; García, Begoña; Espino, Gustavo

    2014-10-20

    The ligands 2-pyridin-2-yl-1H-benzimidazole (HL(1)), 1-methyl-2-pyridin-2-ylbenzimidazole (HL(2)), and 2-(1H-imidazol-2-yl)pyridine (HL(3)) and the proligand 2-phenyl-1H-benzimidazole (HL(4)) have been used to prepare five different types of new ruthenium(II) arene compounds: (i) monocationic complexes with the general formula [(η(6)-arene)RuCl(κ(2)-N,N-HL)]Y [HL = HL(1), HL(2), or HL(3); Y = Cl or BF4; arene = 2-phenoxyethanol (phoxet), benzene (bz), or p-cymene (p-cym)]; (ii) dicationic aqua complexes of the formula [(η(6)-arene)Ru(OH2)(κ(2)-N,N-HL(1))](Y)2 (Y = Cl or TfO; arene = phoxet, bz, or p-cym); (iii) the nucleobase derivative [(η(6)-arene)Ru(9-MeG)(κ(2)-N,N-HL(1))](PF6)2 (9-MeG = 9-methylguanine); (iv) neutral complexes consistent with the formulation [(η(6)-arene)RuCl(κ(2)-N,N-L(1))] (arene = bz or p-cym); (v) the neutral cyclometalated complex [(η(6)-p-cym)RuCl(κ(2)-N,C-L(4))]. The cytototoxic activity of the new ruthenium(II) arene compounds has been evaluated in several cell lines (MCR-5, MCF-7, A2780, and A2780cis) in order to establish structure-activity relationships. Three of the compounds with the general formula [(η(6)-arene)RuCl(κ(2)-N,N-HL(1))]Cl differing in the arene moiety have been studied in depth in terms of thermodynamic dissociation constants, aquation kinetic constants, and DNA binding measurements. The biologically most active compound is the p-cym derivative, which strongly destabilizes the DNA double helix, whereas those with bz and phoxet have only a small effect on the stability of the DNA double helix. Moreover, the inhibitory activity of several compounds toward CDK1 has also been evaluated. The DNA binding ability of some of the studied compounds and their CDK1 inhibitory effect suggest a multitarget mechanism for their biological activity.

  4. New π-arene ruthenium(II) piano-stool complexes with nitrogen ligands.

    PubMed

    Grau, Jordi; Noe, Verónica; Ciudad, Carles; Prieto, Maria J; Font-Bardia, Mercè; Calvet, Teresa; Moreno, Virtudes

    2012-04-01

    The synthesis, characterization, DNA interaction and antiproliferative behavior of new π-arene ruthenium(II) piano-stool complexes with nitrogen ligands are described. Three series of organometallic compounds of formulae [RuCl(2)(η(6)-p-cym)L] were synthesized (with L=2-, 3- or 4-methylpyridine; L=2,3-, 2,4-, 2,5-, 3,4-, 3,5-dimethylpyridine and L=1,2-, 1,3- 1,4-methylaminobenzene). The crystal structures of [RuCl(2)(p-cym)(4-methylpyridine)], [RuCl(2)(p-cym)(3,4-dimethylpyridine)] and [RuCl(2)(p-cym)(1,4-methylaminobenzene)] were resolved and the characterization was completed by spectroscopic UV-vis, FT-IR and (1)H NMR studies. Electrochemical experiments were performed by cyclic voltammetry to estimate the redox potential of the Ru(II)/Ru(III) couple. The interaction with plasmid pBR322 DNA was studied through the examination of the electrophoretical mobility and atomic force microscopy, and interaction with ct-DNA by circular dichroism, viscosity measurements and fluorescence studies based on the DNA-ethidium bromide complex. The antiproliferative behavior of the series with L=methylpyridine was assayed against two tumor cell lines, i.e. LoVo and MiaPaca. The results revealed a moderate cytotoxicity with a higher activity for the LoVo cell line compared to the MiaPaca one. PMID:22387934

  5. Selenoquinones stabilized by ruthenium(II) arene complexes: synthesis, structure, and cytotoxicity.

    PubMed

    Dubarle-Offner, Julien; Clavel, Catherine M; Gontard, Geoffrey; Dyson, Paul J; Amouri, Hani

    2014-05-01

    A new series of monoselenoquinone and diselenoquinone π complexes, [(η(6) -p-cymene)Ru(η(4) -C6 R4 SeE)] (R=H, E=Se (6); R=CH3 , E=Se (7); R=H, E=O (8)), as well as selenolate π complexes [(η(6) -p-cymene)Ru(η(5) -C6 H3 R2 Se)][SbF6 ] (R=H (9); R=CH3 (10)), stabilized by arene ruthenium moieties were prepared in good yields through nucleophilic substitution reactions from dichlorinated-arene and hydroxymonochlorinated-arene ruthenium complexes [(η(6) -p-cymene)Ru(C6 R4 XCl)][SbF6 ]2 (R=H, X=Cl (1); R=CH3 , X=Cl (2); R=H, X=OH (3)) as well as the monochlorinated π complexes [(η(6) -p-cymene)Ru(η(5) -C6 H3 R2 Cl)][SbF6 ]2 (R=H (4); R=CH3 (5)). The X-ray crystallographic structures of two of the compounds, [(η(6) -p-cymene)Ru(η(4) -C6 Me4 Se2 )] (7) and [(η(6) -p-cymene)Ru(η(4) -C6 H4 SeO)] (8), were determined. The structures confirm the identity of the target compounds and ascertain the coordination mode of these unprecedented ruthenium π complexes of selenoquinones. Furthermore, these new compounds display relevant cytotoxic properties towards human ovarian cancer cells.

  6. Radiosensitisation of human colorectal cancer cells by ruthenium(II) arene anticancer complexes

    PubMed Central

    Carter, R; Westhorpe, A; Romero, MJ; Habtemariam, A; Gallevo, CR; Bark, Y; Menezes, N; Sadler, PJ; Sharma, RA

    2016-01-01

    Some of the largest improvements in clinical outcomes for patients with solid cancers observed over the past 3 decades have been from concurrent treatment with chemotherapy and radiotherapy (RT). The lethal effects of RT on cancer cells arise primarily from damage to DNA. Ruthenium (Ru) is a transition metal of the platinum group, with potentially less toxicity than platinum drugs. We postulated that ruthenium-arene complexes are radiosensitisers when used in combination with RT. We screened 14 ruthenium-arene complexes and identified AH54 and AH63 as supra-additive radiosensitisers by clonogenic survival assays and isobologram analyses. Both complexes displayed facial chirality. At clinically relevant doses of RT, radiosensitisation of cancer cells by AH54 and AH63 was p53-dependent. Radiation enhancement ratios for 5–10 micromolar drug concentrations ranged from 1.19 to 1.82. In p53-wildtype cells, both drugs induced significant G2 cell cycle arrest and apoptosis. Colorectal cancer cells deficient in DNA damage repair proteins, EME1 and MUS81, were significantly more sensitive to both agents. Both drugs were active in cancer cell lines displaying acquired resistance to oxaliplatin or cisplatin. Our findings broaden the potential scope for these drugs for use in cancer therapy, including combination with radiotherapy to treat colorectal cancer. PMID:26867983

  7. Antiproliferative activity of ruthenium(ii) arene complexes with mono- and bidentate pyridine-based ligands.

    PubMed

    Richter, Stefan; Singh, Sushma; Draca, Dijana; Kate, Anup; Kumbhar, Anupa; Kumbhar, Avinash S; Maksimovic-Ivanic, Danijela; Mijatovic, Sanja; Lönnecke, Peter; Hey-Hawkins, Evamarie

    2016-08-16

    A series of Ru(II) arene complexes of mono- and bidentate N-donor ligands with carboxyl or ester groups and chlorido ancillary ligands were synthesised and structurally characterised. The complexes have a distorted tetrahedral piano-stool geometry. The binding interaction was studied with calf thymus DNA (CT-DNA) by absorption titration, viscosity measurement, thermal melting, circular dichroism, ethidium bromide displacement assay and DNA cleavage of plasmid DNA (pBR322), investigated by gel electrophoresis. The dichlorido complexes bind covalently to DNA in the dark, similar to cisplatin, while the monochlorido complexes bind covalently on irradiation, similar to cisplatin analogues. The compounds are selectively cytotoxic against several tumour cell lines and show specific nonlinear correlation between dose and activity. This phenomenon is closely related to their potential to act preferentially as inhibitors of cell division. PMID:27264161

  8. Photosubstitution reactions of the ruthenium(II) arene complexes Ru(eta/sup 6/-arene)L/sub 3//sup 2 +/ (L = NH/sub 3/ or H/sub 2/O) in aqueous solution

    SciTech Connect

    Weber, W.; Ford, P.C.

    1986-04-09

    Irradiation of the ruthenium(II) complexes Ru(eta/sup 6/-arene)L/sub 3//sup 2 +/ (arene = benzene, toluene, or isopropyltoluene; L = NH/sub 3/ or H/sub 2/O) in aqueous solution leads in each case to aquation of arene as the only observable photoreaction (Ru(eta/sup 6/-arene)L/sub 3//sup 2 +/ + 3H/sub 2/O ..-->.. Ru(H/sub 2/O)/sub 3/L/sub 3//sup 2 +/ + arene). Quantum yields phi/sub L/ for this process were a function of lambda/sub irr/, relatively low for the irradiation into the lowest energy absorption band but progressively higher at shorter wavelengths. The triammine ion Ru(eta/sup 6/-C/sub 6/H/sub 6/)(NH/sub 3/)/sub 3//sup 2 +/ showed no evidence for amine aquation or for photooxidation to Ru(III). The phi/sub L/ values were found to be nearly independent of whether L = NH/sub 3/ or H/sub 2/O although there are significant spectral differences between these complexes. In contrast, phi/sub L/ was found to be quite responsive to the nature of substituents on the arene ring. The spectral properties and potential mechanisms for arene photosubstitution are discussed.

  9. Microwave-assisted synthesis of arene ruthenium(II) complexes that induce S-phase arrest in cancer cells by DNA damage-mediated p53 phosphorylation.

    PubMed

    Wu, Qiong; Fan, Cundong; Chen, Tianfeng; Liu, Chaoran; Mei, Wenjie; Chen, Sidong; Wang, Baoguo; Chen, Yunyun; Zheng, Wenjie

    2013-05-01

    A series of arene ruthenium(II) complexes coordinated by phenanthroimidazole derivates, [(C6H6)Ru(L)Cl]Cl·2H2O (1b L = IP, 2b L = p-NMe2PIP, 3b L = p-MeOPIP, 4b L = p-HOPIP, 5b L = p-COOHPIP, 6b L = p-CF3PIP, 7b L = p-BrPIP) have been synthesized in yields of 89-92% under microwave irradiation in 30 min, and the crystal structure of 1b by XRD gives a typical "piano stool" conformation. The antitumor activity of these complexes against various tumor cells have been evaluated by MTT assay, and the results show that this type of arene Ru(II) complexes exhibit acceptable inhibitory effect against all of these tumor cells, especially osteosarcoma MG-63 cells, but with low toxicity toward HK-2 human normal cells. Studies on the mechanism revealed that cell cycle arrest at S-phase in MG-63 cells induced by the arene Ru(II) complex 2b, which was confirmed by the increase in the percentage of cells at S-phase and down-regulator of cyclin A. The further studies by Comet assay at single cell level indicated that DNA damage in MG-63 cells was triggered by 2b, following with the up-regulation of phosphorylated p53 and histone. The studies by spectroscopy in vitro also indicate that 2b bind to DNA molecule by intercalative mode to disturb the bio-function of tumor cells. In conclusion, the synthetic arene Ru(II) complexes could serve as novel p53 activator with potential application in cancer chemotherapy.

  10. Influence of the π-coordinated arene on the anticancer activity of ruthenium(II) carbohydrate organometallic complexes

    PubMed Central

    Hanif, Muhammad; Meier, Samuel M.; Nazarov, Alexey A.; Risse, Julie; Legin, Anton; Casini, Angela; Jakupec, Michael A.; Keppler, Bernhard K.; Hartinger, Christian G.

    2013-01-01

    The synthesis and in vitro cytotoxicity of a series of RuII(arene) complexes with carbohydrate-derived phosphite ligands and various arene co-ligands is described. The arene ligand has a strong influence on the in vitro anticancer activity of this series of compounds, which correlates fairly well with cellular accumulation. The most lipophilic compound bearing a biphenyl moiety and a cyclohexylidene-protected carbohydrate is the most cytotoxic with unprecedented IC50 values for the compound class in three human cancer cell lines. This compound shows reactivity to the DNA model nucleobase 9-ethylguanine, but does not alter the secondary structure of plasmid DNA, indicating that other biological targets are responsible for its cytotoxic effect. PMID:24790955

  11. Influence of the π-coordinated arene on the anticancer activity of ruthenium(II) carbohydrate organometallic complexes

    NASA Astrophysics Data System (ADS)

    Hanif, Muhammad; Meier, Samuel; Nazarov, Alexey; Risse, Julie; Legin, Anton; Casini, Angela; Jakupec, Michael; Keppler, Bernhard; Hartinger, Christian

    2013-10-01

    The synthesis and in vitro cytotoxicity of a series of RuII(arene) complexes with carbohydrate-derived phosphite ligands and various arene co-ligands is described. The arene ligand has a strong influence on the in vitro anticancer activity of this series of compounds, which correlates fairly well with cellular accumulation. The most lipophilic compound bearing a biphenyl moiety and a cyclohexylidene-protected carbohydrate is the most cytotoxic with unprecedented IC50 values for the compound class in three human cancer cell lines. This compound shows reactivity to the DNA model nucleobase 9-ethylguanine, but does not alter the secondary structure of plasmid DNA indicating that other biological targets are responsible for its cytotoxic effect.

  12. Electrophilic Activation of Oxidized Sulfur Ligands and Implications for the Biological Activity of Ruthenium(II) Arene Anticancer Complexes.

    PubMed

    Sriskandakumar, Thamayanthy; Behyan, Shirin; Habtemariam, Abraha; Sadler, Peter J; Kennepohl, Pierre

    2015-12-01

    Surprisingly, the anticancer activity of half-sandwich Ru arene complexes [(η(6)-arene)Ru(en)Cl](+) appears to be promoted and not inhibited by binding to the intracellular thiol glutathione. Labilization of the Ru-S bond allowing DNA binding appeared to be initiated by oxygenation of the thiolate ligand, although oxidation by itself did not seem to weaken the Ru-S bond. In this study, we have investigated the solvation and acidic perturbations of mono (sulfenato) and bis (sulfinato) oxidized species of [(η(6)-arene)Ru(en) (SR)](+) complex in the presence of Brønsted and Lewis acids. Sulfur K-edge X-ray absorption spectroscopy together with density functional theory calculations show that solvation and acidic perturbation of sulfenato species produce a significant decrease in the S3p character of the Ru-S bond (Ru4dσ* ← S1s charge donation). Also there is a drastic fall in the overall ligand charge donation to the metal center in both sulfenato and sulfinato species. Our investigation clearly shows that mono oxidized sulfenato species are most susceptible to ligand exchange, hence providing a possible pathway for in vivo activation and biological activity.

  13. Antimalarial activity of ruthenium(II) and osmium(II) arene complexes with mono- and bidentate chloroquine analogue ligands.

    PubMed

    Ekengard, Erik; Glans, Lotta; Cassells, Irwin; Fogeron, Thibault; Govender, Preshendren; Stringer, Tameryn; Chellan, Prinessa; Lisensky, George C; Hersh, William H; Doverbratt, Isa; Lidin, Sven; de Kock, Carmen; Smith, Peter J; Smith, Gregory S; Nordlander, Ebbe

    2015-11-28

    Eight new ruthenium and five new osmium p-cymene half-sandwich complexes have been synthesized, characterized and evaluated for antimalarial activity. All complexes contain ligands that are based on a 4-chloroquinoline framework related to the antimalarial drug chloroquine. Ligands HL(1-8) are salicylaldimine derivatives, where HL(1) = N-(2-((2-hydroxyphenyl)methylimino)ethyl)-7-chloroquinolin-4-amine, and HL(2-8) contain non-hydrogen substituents in the 3-position of the salicylaldimine ring, viz. F, Cl, Br, I, NO2, OMe and (t)Bu for HL(2-8), respectively. Ligand HL(9) is also a salicylaldimine-containing ligand with substitutions in both 3- and 5-positions of the salicylaldimine moiety, i.e. N-(2-((2-hydroxy-3,5-di-tert-butylphenyl)methyl-imino)ethyl)-7-chloroquinolin-4-amine, while HL(10) is N-(2-((1-methyl-1H-imidazol-2-yl)methylamino)ethyl)-7-chloroquinolin-4-amine) The half sandwich metal complexes that have been investigated are [Ru(η(6)-cym)(L(1-8))Cl] (Ru-1-Ru-8, cym = p-cymene), [Os(η(6)-cym)(L(1-3,5,7))Cl] (Os-1-Os-3, Os-5, and Os-7), [M(η(6)-cym)(HL(9))Cl2] (M = Ru, Ru-HL(9); M = Os, Os-HL(9)) and [M(η(6)-cym)(L(10))Cl]Cl (M = Ru, Ru-10; M = Os, Os-10). In complexes Ru-1-Ru-8 and Ru-10, Os-1-Os-3, Os-5 and Os-7 and Os-10, the ligands were found to coordinate as bidentate N,O- and N,N-chelates, while in complexes Ru-HL(9) and Os-HL(9), monodentate coordination of the ligands through the quinoline nitrogen was established. The antimalarial activity of the new ligands and complexes was evaluated against chloroquine sensitive (NF54 and D10) and chloroquine resistant (Dd2) Plasmodium falciparum malaria parasite strains. Coordination of ruthenium and osmium arene moieties to the ligands resulted in lower antiplasmodial activities relative to the free ligands, but the resistance index is better for the ruthenium complexes compared to chloroquine. Overall, osmium complexes appeared to be less active than the corresponding ruthenium complexes. PMID:26491831

  14. Anticancer activity of ruthenium(II) arene complexes bearing 1,2,3,4-tetrahydroisoquinoline amino alcohol ligands.

    PubMed

    Chelopo, Madichaba P; Pawar, Sachin A; Sokhela, Mxolisi K; Govender, Thavendran; Kruger, Hendrik G; Maguire, Glenn E M

    2013-08-01

    Ruthenium complexes offer potential reduced toxicity compared to current platinum anticancer drugs. 1,2,3,4-tetrahydrisoquinoline amino alcohol ligands were synthesised, characterised and coordinated to an organometallic Ru(II) centre. These complexes were evaluated for activity against the cancer cell lines MCF-7, A549 and MDA-MB-231 as well as for toxicity in the normal cell line MDBK. They were observed to be moderately active against only the MCF-7 cells with the best IC₅₀ value of 34 μM for the cis-diastereomeric complex C4. They also displayed excellent selectivity by being relatively inactive against the normal MDBK cell line with SI values ranging from 2.3 to 7.4. PMID:23827181

  15. Anticancer activity of ruthenium(II) arene complexes bearing 1,2,3,4-tetrahydroisoquinoline amino alcohol ligands.

    PubMed

    Chelopo, Madichaba P; Pawar, Sachin A; Sokhela, Mxolisi K; Govender, Thavendran; Kruger, Hendrik G; Maguire, Glenn E M

    2013-08-01

    Ruthenium complexes offer potential reduced toxicity compared to current platinum anticancer drugs. 1,2,3,4-tetrahydrisoquinoline amino alcohol ligands were synthesised, characterised and coordinated to an organometallic Ru(II) centre. These complexes were evaluated for activity against the cancer cell lines MCF-7, A549 and MDA-MB-231 as well as for toxicity in the normal cell line MDBK. They were observed to be moderately active against only the MCF-7 cells with the best IC₅₀ value of 34 μM for the cis-diastereomeric complex C4. They also displayed excellent selectivity by being relatively inactive against the normal MDBK cell line with SI values ranging from 2.3 to 7.4.

  16. Cyclometallation of arylimines and nitrogen-containing heterocycles via room-temperature C-H bond activation with arene ruthenium(II) acetate complexes.

    PubMed

    Li, Bin; Roisnel, Thierry; Darcel, Christophe; Dixneuf, Pierre H

    2012-08-28

    The reaction of [RuCl(2)(p-cymene)](2) with arylimines and 4 equiv. of KOAc in methanol at room temperature produces stable (N^C)-cyclometallated ruthenium(II) complexes via C-H bond activation/deprotonation. This method can be applied also to nitrogen-containing molecules: N-phenylpyrazole, 2-phenyl-2-oxazoline and benzo[h]quinoline. N-Phenyl-pyrazole, [RuCl(2)(p-cymene)](2) and diphenylacetylene directly lead to alkyne insertion into the metallacycle C-Ru bond. PMID:22890507

  17. New ruthenium(II) arene complexes of anthracenyl-appended diazacycloalkanes: effect of ligand intercalation and hydrophobicity on DNA and protein binding and cleavage and cytotoxicity.

    PubMed

    Ganeshpandian, Mani; Loganathan, Rangasamy; Suresh, Eringathodi; Riyasdeen, Anvarbatcha; Akbarsha, Mohammad Abdulkadher; Palaniandavar, Mallayan

    2014-01-21

    A series of half-sandwich Ru(II) arene complexes of the type [Ru(η(6)-arene)(L)Cl](PF6) 1-4, where arene is benzene (1, 2) or p-cymene (3, 4) and L is N-methylhomopiperazine (L1) or 1-(anthracen-10-ylmethyl)-4-methylhomopiperazine (L2), has been isolated and characterized by using spectral methods. The X-ray crystal structures of 2, 3 and 4 reveal that the compounds possess a pseudo-octahedral "piano-stool" structure equipped with the arene ligand as the seat and the bidentate ligand and the chloride ion as the legs of the stool. The DNA binding affinity determined using absorption spectral titrations with CT DNA and competitive DNA binding studies varies as 4 > 2 > 3 > 1, depending upon both the arene and diazacycloalkane ligands. Complexes 2 and 4 with higher DNA binding affinities show strong hypochromism (56%) and a large red-shift (2, 10; 4, 11 nm), which reveals that the anthracenyl moiety of the ligand is stacked into the DNA base pairs and that the arene ligand hydrophobicity also dictates the DNA binding affinity. In contrast, the monocationic complexes 1 and 3 are involved in electrostatic binding in the minor groove of DNA. The enhancement in viscosities of CT DNA upon binding to 2 and 4 are higher than those for 1 and 3 supporting the DNA binding modes of interaction inferred. All the complexes cleave DNA effectively even in the absence of an external agent and the cleavage ability is enhanced in the presence of an activator like H2O2. Tryptophan quenching measurements suggest that the protein binding affinity of the complexes varies as 4 > 2 > 3 > 1, which is the same as that for DNA binding and that the fluorescence quenching of BSA occurs through a static mechanism. The positive ΔH(0) and ΔS(0) values for BSA binding of complexes indicate that the interaction between the complexes and BSA is mainly hydrophobic in nature and the energy transfer efficiency has been analysed according to the Förster non-radiative energy transfer theory. The

  18. Novel N-coordinate half-sandwich ruthenium(II) arene complexes bearing sulfonamide fragments: Catalytic activities in the TH of acetophenone derivatives

    NASA Astrophysics Data System (ADS)

    Kayaci, Nilgün; Dayan, Serkan; Kalaycioglu Ozpozan, Nilgun

    2015-11-01

    The novel cationic N-coordinate ruthenium(II)/arene complexes (6-10) were prepared from the starting complex [RuCl2(p-cymene)]2 dimer. The structures of the [(p-cymene)RuLCl]Cl (L = N-arenesulfonyl-4,5-dimethyl-o-phenylenediamines) complexes were elucidated by FT-IR, 1H-NMR, 13C-NMR, ionic conductivity techniques, and elemental analysis methods. The 6-10 complexes were applied as catalyst in the transfer hydrogenation (TH) of ketones. The catalytic tests showed that all the complexes are moderate catalysis precursors. Especially, {[N-benzenesulfonyl-4,5-dimethyl-o-phenylenediamine]-(p-cymene)-di-chloro-ruthenium(II)} (8) and {[N-4-chlorobenzenesulfonyl-4,5-dimethyl-o-phenylenediamine]-(p-cymene)-di-chloro-ruthenium(II)} (9) compounds were found to be a good catalysts in comparison to the others giving the corresponding alcohols in a good turnover frequency value of 1534 and 1731 h-1, respectively.

  19. The 1:1 co-crystallization of enantiomers of an arene-tethered and ortho-metallated N-heterocyclic carbene ruthenium(II) half-sandwich complex: Synthesis, structural characterization and theoretical study

    NASA Astrophysics Data System (ADS)

    Karabıyık, Hasan; Kılınçarslan, Rafet; Aygün, Muhittin; Çetinkaya, Bekir; García-Granda, Santiago

    2008-01-01

    The reaction of [RuCl 2( p-cymene)] 2 with in situ deprotonated NHC precursor 1,3-bis(biphenyl-2-yl)imidazolinium chloride was carried out in p-xylene at 140 °C to produce ?2, in which the NHC moiety acts as a tridentate C,C',C''-ligand. The complex 2 was characterized by NMR spectroscopy and X-ray crystallographic study. Crystallographic analysis combined with computational study regarding the compound, 1-[η 6-(2'-biphenyl)]-3-[2-phenyl-1,2-phenylene]imidazolidin-2-ylidenechlororuthenium(II), 2, reveals that its metal-centered enantiomers are co-crystallized in 1:1 ratio and NHC frame possessing a tridentate coordination mode consists of σ-donation of the carbene carbon, η 6-arene tethering of terminal biaryl and η 1-coordination of the biphenyl ring at 2-position. Enantiomers of the complex are packed as asymmetric dimers in solid state formed by C-H⋯Cl type weak H-bonds and C-H⋯π type interactions giving rise to asymmetric chains. Both interactions serve to stabilization of the extended structure.

  20. Molecular Models of Ruthenium(II) Organometallic Complexes

    ERIC Educational Resources Information Center

    Coleman, William F.

    2007-01-01

    This article presents the featured molecules for the month of March, which appear in the paper by Ozerov, Fafard, and Hoffman, and which are related to the study of the reactions of a number of "piano stool" complexes of ruthenium(II). The synthesis of compound 2a offers students an alternative to the preparation of ferrocene if they are only…

  1. Pillar[6]arene-based photoresponsive host-guest complexation.

    PubMed

    Yu, Guocan; Han, Chengyou; Zhang, Zibin; Chen, Jianzhuang; Yan, Xuzhou; Zheng, Bo; Liu, Shiyong; Huang, Feihe

    2012-05-23

    The trans form of an azobenzene-containing guest can complex with a pillar[6]arene, while it cannot complex with pillar[5]arenes due to the different cavity sizes of the pillar[6]arene and the pillar[5]arenes. The spontaneous aggregation of its host-guest complex with the pillar[6]arene can be reversibly photocontrolled by irradiation with UV and visible light, leading to a switch between irregular aggregates and vesicle-like aggregates. This new pillar[6]arene-based photoresponsive host-guest recognition motif can work in organic solvents and is a good supplement to the existing widely used cyclodextrin/azobenzene recognition motif.

  2. Langmuir films of calix[8] arene/fullerene complexes

    SciTech Connect

    Castillo, R.; Ramos, S.; Cruz, R.; Martinez, M.; Lara, F.; Ruiz-Garcia, J.

    1996-01-11

    We present the pressure area isotherms for Langmuir films made of calix[8]arene, the calix[8]arene/C{sub 60} complex, and the calix[8]arene/C{sub 70} complex, all of them measured at 306.1 K. A Brewster angle microscope was used to observe the phases shown by {Pi}-A isotherms. In these three cases, we found a solid phase and its solid-gas coexistence but no expanded liquid phases. The Langmuir films of calix[8]arene and the calix[8]arene/C{sub 60} complex are very similar. The experimental information is consistent with the assumption that C{sub 60} is situated inside the cavity of calix[8]arene. The Langmuir films of calix[8]arene and the calix[8]arene/C{sub 70} complex are not very similar; we present a discussion to explain the origin of this difference. 23 refs., 5 figs.

  3. A selective, long-lived deep-red emissive ruthenium(II) polypyridine complexes for the detection of BSA.

    PubMed

    Babu, Eththilu; Muthu Mareeswaran, Paulpandian; Singaravadivel, Subramanian; Bhuvaneswari, Jayaraman; Rajagopal, Seenivasan

    2014-09-15

    A selective, label free luminescence sensor for bovine serum albumin (BSA) is investigated using ruthenium(II) complexes over the other proteins. Interaction between BSA and ruthenium(II) complexes has been studied using absorption, emission, excited state lifetime and circular dichroism (CD) spectral techniques. The luminescence intensity of ruthenium(II) complexes (I and II), has enhanced at 602 and 613 nm with a large hypsochromic shift of 18 and 5 nm respectively upon addition of BSA. The mode of binding of ruthenium(II) complexes with BSA has analyzed using computational docking studies.

  4. Arene-thioether mixed complex radical cations

    SciTech Connect

    Werst, D.W.

    1994-03-01

    Studies of radiolytically generated radical cations in aromatic hydrocarbon solvents have led to the first direct characterization of monomeric thioether radical cations in liquid solution. Observation of these very reactive chemical intermediates is made possible by the great sensitivity of fluorescence-detected magnetic resonance (FDMR) and by solvent stabilization of the thioether radical cations via electron donation. Monomeric thioether radical cations in arene solvents such as toluene exist as arene-thioether mixed complex radical cations -- the first {pi}-lone pair mixed complex radical cations ever observed. Such orbital interactions are of fundamental importance for open-shell intermediates as they have consequences for both electronic structure and reactivity. Thioether radical cations provide a valuable test system to probe the chemical influence of orbital interactions that are generic to all {pi}-type and heteroatom-containing organic radical cations, and magnetic resonance provides unsurpassed structural resolution for condensed-phase paramagnetic intermediates.

  5. Unusual mode of protein binding by a cytotoxic π-arene ruthenium(ii) piano-stool compound containing an O,S-chelating ligand.

    PubMed

    Hildebrandt, Jana; Görls, Helmar; Häfner, Norman; Ferraro, Giarita; Dürst, Matthias; Runnebaum, Ingo B; Weigand, Wolfgang; Merlino, Antonello

    2016-08-01

    A new pseudo-octahedral π-arene ruthenium(ii) piano-stool compound, containing an O,S-bidentate ligand (compound 1) and showing significant cytotoxic activity in vitro, was synthesized and characterized. In solution stability and interaction with the model protein bovine pancreatic ribonuclease (RNase A) were investigated by using UV-Vis absorption spectroscopy. Its crystal structure and that of the adduct formed upon reaction with RNase A were obtained by X-ray crystallography. The comparison between the structure of purified compound 1 and that of the fragment bound to RNase A reveals an unusual mode of protein binding that includes ligand exchange and alteration of coordination sphere geometry. PMID:27427335

  6. Unusual mode of protein binding by a cytotoxic π-arene ruthenium(ii) piano-stool compound containing an O,S-chelating ligand.

    PubMed

    Hildebrandt, Jana; Görls, Helmar; Häfner, Norman; Ferraro, Giarita; Dürst, Matthias; Runnebaum, Ingo B; Weigand, Wolfgang; Merlino, Antonello

    2016-08-01

    A new pseudo-octahedral π-arene ruthenium(ii) piano-stool compound, containing an O,S-bidentate ligand (compound 1) and showing significant cytotoxic activity in vitro, was synthesized and characterized. In solution stability and interaction with the model protein bovine pancreatic ribonuclease (RNase A) were investigated by using UV-Vis absorption spectroscopy. Its crystal structure and that of the adduct formed upon reaction with RNase A were obtained by X-ray crystallography. The comparison between the structure of purified compound 1 and that of the fragment bound to RNase A reveals an unusual mode of protein binding that includes ligand exchange and alteration of coordination sphere geometry.

  7. The synthesis and antiparasitic activity of aryl- and ferrocenyl-derived thiosemicarbazone ruthenium(II)-arene complexes.

    PubMed

    Adams, Muneebah; Li, Yiqun; Khot, Heena; De Kock, Carmen; Smith, Peter J; Land, Kirkwood; Chibale, Kelly; Smith, Gregory S

    2013-04-01

    A series of aryl-functionalized and ferrocenyl monothiosemicarbazone compounds (L1-L4) were synthesized in moderate yields via a general Schiff-base condensation reaction. The thiosemicarbazone (TSC) ligands were reacted with the ruthenium dimer [Ru(Ar)(μ-Cl)Cl](2) (Ar = benzene; p-cymene) to yield a series of cationic mononuclear ruthenium(II)-arene thiosemicarbazone complexes of the general type [Ru(Cl)(TSC)(Ar)]Cl (1-8). The thiosemicarbazone ligands act as bidentate chelating ligands that coordinate to the ruthenium(ii) ion via the imine nitrogen and the thione sulfur atoms. The thiosemicarbazone ligands, as well as their metal complexes, were characterized by NMR, IR spectroscopy and ESI(+)-mass spectrometry. The molecular structure of the mononuclear ruthenium(II)-arene thiosemicarbazone complex (6) was determined by single-crystal X-ray diffraction analysis. The ruthenium(II)-arene thiosemicarbazone complexes were further evaluated for their in vitro antiparasitic activities against the Plasmodium falciparum chloroquine-sensitive (NF54) and chloroquine-resistant (Dd2) strains, as well as the G3 strain of Trichomonas vaginalis.

  8. Protein Nanocages for Delivery and Release of Luminescent Ruthenium(II) Polypyridyl Complexes.

    PubMed

    Li, Xiao; Zhang, Yajie; Chen, Hong; Sun, Jian; Feng, Fude

    2016-09-01

    In this report, noncovalent encapsulation of hydrophobic ruthenium(II) polyridyl complexes, Ru(bpy)2dppz(2+) and Ru(phen)2dppz(2+), into apoferritin cavity was achieved with high loading contents by effective prevention of Ru complex-induced protein aggregation, without disruption of protein native architecture. The Ru-loaded luminescent nanocomposites have demonstrated improved water solubility, easy manipulation, reduced cytotoxicity, and enhanced cellular uptake as compared to the nontreated Ru complexes. PMID:27547981

  9. Mono and dinuclear arene ruthenium(II) triazoles by 1,3-dipolar cycloadditions to a coordinated azide in ruthenium(II) compounds.

    PubMed

    Singh, Keisham Sarjit; Svitlyk, Volodymyr; Mozharivskyj, Yurij

    2011-02-01

    The dimeric η(6)-hexamethylbenzene ruthenium(II) triazole compounds of formulation [{(η(6)-C(6)Me(6))Ru(N(3)C(2)(CO(2)R)(2))}(2)(μC(2)O(4))] have been synthesized by 1,3-diploar cycloadditions of coordinated azido compound [{(η(6)-C(6)Me(6))Ru(L(1))N(3)}] (1) with substituted acetylene, RO(2)CC(2)CO(2)R via unexpected oxidation of the coordinated ligand to oxalate (where; L(1) = 5-hydroxy-2-(hydroxymethyl)-4-pyrone; R = Me, 3 or Et, 4). In contrast, a similar 1,3-dipolar cycloaddition reaction of [{(η(6)-C(6)Me(6))Ru(L(2))N(3)}] (2) (where; L(2) = tropolone) with acetylene yielded the monomeric triazole compound [(η(6)-C(6)Me(6))Ru(L(2)){N(3)C(2)(CO(2)R)(2)}] (where; R = Me, 5; Et, 6). The compounds were characterized by spectroscopy and the structures of representative compounds 4 and 6 have been determined by single crystal X-ray diffraction. The two ruthenium centres in the compound 4, are linked by a tetra-dentate oxalate group. Both compounds, 4 and 6, crystallized in a triclinic space group P-1.

  10. Proline as chiral auxiliary for the economical asymmetric synthesis of ruthenium(II) polypyridyl complexes.

    PubMed

    Fu, Chen; Wenzel, Marianne; Treutlein, Elisabeth; Harms, Klaus; Meggers, Eric

    2012-09-17

    A straightforward method for the synthesis of virtually enantiomerically pure ruthenium(II) polypyridyl complexes [Ru(pp)(pp')(pp")](PF(6))(2), pp = bidentate polypyridyl has been developed. The synthesis draws from the readily available racemic starting material cis-[Ru(pp)(pp')Cl(2)] and the natural amino acids l- or d-proline and relies on a dynamic asymmetric transformation under thermodynamic control.

  11. Organometallic osmium arene complexes with potent cancer cell cytotoxicity.

    PubMed

    Fu, Ying; Habtemariam, Abraha; Pizarro, Ana M; van Rijt, Sabine H; Healey, David J; Cooper, Patricia A; Shnyder, Steven D; Clarkson, Guy J; Sadler, Peter J

    2010-11-25

    Iodido osmium(II) complexes [Os(η(6)-arene)(XY)I](+) (XY = p-hydroxy or p-dimethylaminophenylazopyridine, arene = p-cymene or biphenyl) are potently cytotoxic at nanomolar concentrations toward a panel of human cancer cell lines; e.g., IC(50) = 140 nM for [Os(η(6)-bip)(azpy-NMe(2))I](+) toward A2780 ovarian cancer cells. They exhibit low toxicity and negligible deleterious effects in a colon cancer xenograft model, giving rise to the possibility of a broad therapeutic window. The most active complexes are stable and inert toward aquation. Their cytotoxic activity appears to involve redox mechanisms.

  12. Metal arene complexes in coal structure determination: Quarterly report for the period, September 1986-November 1986. [Arenetricarbonylchromium complex anion; arene iron complex anion

    SciTech Connect

    Woolsey, N.F.

    1986-12-01

    Continued investigation of arene metal (Cr, Fe) complexes for methods of ..cap alpha..-alkyl group cleavage has shown several advances during this quarter. Peroxide oxidation of an arenetricarbonylchromium complex anion has given preliminary evidence for phenol formation by methyl group removal. An arene iron complex anion was shown to react by 1,3-dipolar cycloaddition but did not show cleavage of an alkyl group from the arene ring. A postulated rhodium complex sequence where metal insertion into a carbonyl ..cap alpha.. bond provides a formal method to achieve the objectives of the proposed research when taken in conjunction with ..cap alpha..-oxidation of arene metal complex anions. All of these reactions or procedures are in their preliminary stages at present but look very promising. 2 refs.

  13. A Ruthenium(II) Complex Supported by Trithiacyclononane and Aromatic Diimine Ligand as Luminescent Switch-On Probe for Biomolecule Detection and Protein Staining

    NASA Astrophysics Data System (ADS)

    Wong, Chun-Yuen; Chung, Lai-Hon; Lin, Sheng; Chan, Daniel Shiu-Hin; Leung, Chung-Hang; Ma, Dik-Lung

    2014-11-01

    A new ruthenium(II) complex has been developed for detection of biomolecules. This complex is highly selective for histidine over other amino acids and has been applied to protein staining in an SDS-PAGE gel.

  14. A Ruthenium(II) Complex Supported by Trithiacyclononane and Aromatic Diimine Ligand as Luminescent Switch-On Probe for Biomolecule Detection and Protein Staining

    PubMed Central

    Wong, Chun-Yuen; Chung, Lai-Hon; Lin, Sheng; Chan, Daniel Shiu-Hin; Ma, Dik-Lung

    2014-01-01

    A new ruthenium(II) complex has been developed for detection of biomolecules. This complex is highly selective for histidine over other amino acids and has been applied to protein staining in an SDS-PAGE gel. PMID:25409703

  15. Photoinduced interactions of supramolecular ruthenium(II) complexes with plasmid DNA: synthesis and spectroscopic, electrochemical, and DNA photocleavage studies.

    PubMed

    Swavey, Shawn; DeBeer, Madeleine; Li, Kaiyu

    2015-04-01

    Two new bridging ligands have been synthesized by combining substituted benzaldehydes with phenanthrolinopyrrole (php), resulting in new polyazine bridging ligands. The ligands have been characterized by (1)H NMR, mass spectroscopy, and elemental analysis. These new ligands display π-π* transitions above 500 nm with modest molar absorptivities. Upon excitation at the ligand-centered charge-transfer transition, weak emission with a maximum wavelength of 612 nm is observed. When coordinated to two ruthenium(II) bis(bipyridyl) groups, the new bimetallic complexes generated give an overall 4+ charge. The electronic transitions of the bimetallic ruthenium(II) complexes display traditional π-π* transitions at 287 nm and metal-to-ligand charge-transfer transitions at 452 nm with molar absorptivities greater than 30000 M(-1) cm(-1). Oxidation of the ruthenium(II) metal centers to ruthenium(III) occurs at potentials above 1.4 V versus the Ag/AgCl reference electrode. Spectroscopic and electrochemical measurements indicate that the ruthenium(II) moieties behave independently. Both complexes are water-soluble and show the ability to photonick plasmid DNA when irradiated with low-energy light above 550 nm. In addition, one of the complexes, [Ru(bpy)2php]2Van(4+), shows the ability to linearize plasmid DNA and gives evidence, by gel electrophoresis, of photoinduced binding to plasmid DNA. PMID:25798576

  16. Ruthenium- and osmium-arene-based paullones bearing a TEMPO free-radical unit as potential anticancer drugs.

    PubMed

    Arion, Vladimir B; Dobrov, Anatolie; Göschl, Simone; Jakupec, Michael A; Keppler, Bernhard K; Rapta, Peter

    2012-09-01

    A modified paullone ligand bearing a TEMPO free-radical unit (HL) and its ruthenium(II) and osmium(II)-arene complexes [M(p-cymene)(HL)Cl]Cl·nH(2)O (M = Ru, Os) exhibit high antiproliferative activity in human cancer cell lines.

  17. Ruthenium(II) complexes containing quinone based ligands: Synthesis, characterization, catalytic applications and DNA interaction

    NASA Astrophysics Data System (ADS)

    Anitha, P.; Manikandan, R.; Endo, A.; Hashimoto, T.; Viswanathamurthi, P.

    2012-12-01

    1,2-Naphthaquinone reacts with amines such as semicarbazide, isonicotinylhydrazide and thiosemicarbazide in high yield procedure with the formation of tridentate ligands HLn (n = 1-3). By reaction of ruthenium(II) starting complexes and quinone based ligands HLn (n = 1-3), a series of ruthenium complexes were synthesized and characterized by elemental and spectroscopic methods (FT-IR, electronic, 1H, 13C, 31P NMR and ESI-MS). The ligands were coordinated to ruthenium through quinone oxygen, imine nitrogen and enolate oxygen/thiolato sulfur. On the basis of spectral studies an octahedral geometry may be assigned for all the complexes. Further, the catalytic oxidation of primary, secondary alcohol and transfer hydrogenation of ketone was carried out. The DNA cleavage efficiency of new complexes has also been tested.

  18. Ruthenium(II) complexes containing quinone based ligands: synthesis, characterization, catalytic applications and DNA interaction.

    PubMed

    Anitha, P; Manikandan, R; Endo, A; Hashimoto, T; Viswanathamurthi, P

    2012-12-01

    1,2-Naphthaquinone reacts with amines such as semicarbazide, isonicotinylhydrazide and thiosemicarbazide in high yield procedure with the formation of tridentate ligands HL(n) (n=1-3). By reaction of ruthenium(II) starting complexes and quinone based ligands HL(n) (n=1-3), a series of ruthenium complexes were synthesized and characterized by elemental and spectroscopic methods (FT-IR, electronic, (1)H, (13)C, (31)P NMR and ESI-MS). The ligands were coordinated to ruthenium through quinone oxygen, imine nitrogen and enolate oxygen/thiolato sulfur. On the basis of spectral studies an octahedral geometry may be assigned for all the complexes. Further, the catalytic oxidation of primary, secondary alcohol and transfer hydrogenation of ketone was carried out. The DNA cleavage efficiency of new complexes has also been tested. PMID:23063861

  19. Syntheses and properties of phosphine-substituted ruthenium(II) polypyridine complexes with nitrogen oxides.

    PubMed

    Nakamura, Go; Kondo, Mio; Crisalli, Meredith; Lee, Sze Koon; Shibata, Akane; Ford, Peter C; Masaoka, Shigeyuki

    2015-10-21

    Four novel phosphine-substituted ruthenium(ii) polypyridine complexes with nitrogen oxides-trans(P,NO2)-[Ru(trpy)(Pqn)(NO2)]PF6 (trans-NO2), cis(P,NO2)-[Ru(trpy)(Pqn)(NO2)]PF6 (cis-NO2), [Ru(trpy)(dppbz)(NO2)]PF6 (PP-NO2), and cis(P,NO)-[Ru(trpy)(Pqn)(NO)](PF6)3 (cis-NO)-were synthesised (trpy = 2,2':6',2''-terpyridine, Pqn = 8-(diphenylphosphanyl)quinoline, and dppbz = 1,2-bis(diphenylphosphanyl)benzene). The influence of the number and position of the phosphine group(s) on the electronic structure of these complexes was investigated using single-crystal X-ray structural analysis, UV-vis absorption spectroscopy, and electrochemical measurements. The substitution lability of the nitrogen oxide ligand of each complex is discussed in comparison with that of the corresponding acetonitrile complexes.

  20. Arene Binding Affinities in [CpRu(nu6-arene)]+ Complexes: Models for the Adsorption of Arenes on Hydroesulferization Catalysts

    SciTech Connect

    Choi, M. G.; Ho, T. C.; Angelici, R.

    2008-02-29

    Product/reactant ratios (Y) were determined for the reactions CpRu({eta}{sup 6}-DBT){sup +} + L CpRu({eta}{sup 6}-L){sup +} + DBT (where DBT is dibenzothiophene and L is a homo- or heterocyclic arene), which were conducted under UV photolysis conditions. In the photostationary state, the Y values for the different arenes decrease in the following order: mesitylene (17) > toluene (13) > indole (9.1) > carbazole (6.7) > benzene (5.9) > fluorene (5.1) > biphenyl (3.9) > DBT (1.0) > phenanthrene (0.65) > naphthalene (0.35). In general, alkyl-substituted arenes have a higher binding affinity than the parent arene, except for tert-butyl groups, which decrease the Y values. These trends in {eta}{sup 6}-arene binding to CpRu{sup +} provide a basis for understanding competitive adsorption of arenes on metal sites of hydrotreating catalysts. Such arene components in petroleum feedstocks reduce the rates of hydrodesulfurization of dibenzothiophenes.

  1. Ruthenium(II) hydrazone Schiff base complexes: Synthesis, spectral study and catalytic applications

    NASA Astrophysics Data System (ADS)

    Manikandan, R.; Viswanathamurthi, P.; Muthukumar, M.

    2011-12-01

    Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B = PPh 3, AsPh 3 or Py; L = hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh 3) 2(B)] (where E = P or As; B = PPh 3, AsPh 3 or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, 1H, 13C and 31P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

  2. Efficient water oxidation catalyzed by mononuclear ruthenium(II) complexes incorporating Schiff base ligands.

    PubMed

    Li, Ting-Ting; Chen, Yong; Li, Fu-Min; Zhao, Wei-Liang; Wang, Chuan-Jun; Lv, Xiao-Jun; Xu, Quan-Qing; Fu, Wen-Fu

    2014-06-23

    Four new charge-neutral ruthenium(II) complexes containing dianionic Schiff base and isoquinoline or 4-picoline ligands were synthesized and characterized by NMR and ESI-MS spectroscopies, elemental analysis, and X-ray diffraction. The complexes exhibited excellent chemical water oxidation activity and high stability under acidic conditions (pH 1.0) using (NH4)2Ce(NO3)6 as a sacrificial electron acceptor. The high catalytic activities of these complexes for water oxidation were sustained for more than 10 h at low concentrations. High turnover numbers of up to 3200 were achieved. A water nucleophilic attack mechanism was proposed. A Ru(V)=O intermediate was detected during the catalytic cycle by high-resolution mass spectrometry.

  3. Molecular dinitrogen complexes of ruthenium(II) porphyrins

    SciTech Connect

    Camenzind, M.J.; James, B.R.; Dolphin, D.; Sparapany, J.W.; Ibers, J.A.

    1988-08-24

    The existence of both mono- and bis(nitrogen) complexes of ruthenium have been previously established. Details on a series of complexes are presented herein, and results of an x-ray crystallographic study of Ru(TMP) (THF) (N/sub 2/) are reported. 30 references, 4 tables.

  4. Gas-phase ion chemistry of Cr(. eta. sup 6 -arene)(CO) sub 3 complexes by FTMS techniques

    SciTech Connect

    Operti, L.; Vaglio, G.A. ); Gord, J.R.; Freiser, B.S. )

    1991-01-01

    The gas-phase reactivities of eight Cr({eta}{sup 6}-arene)(CO){sub 3} complexes (arene = toluene, mesitylene, PhCOOOMe, PhCOMe, PhCOEt, PhCO-n-Pr, PhCO-t-Bu, PhCH{sub 2}COMe) have been studied by FTMS techniques. Self-condensation processes occur that follow different reaction pathways when the coordinated arene is a hydrocarbon or a phenyl ketone. PhCOOOMe and PhCH{sub 2}COMe show an intermediate behavior. Reactions with free arenes or propene give substitution of the carbonyl groups, yielding Cr(arene)(arene{prime}){sup +} and Cr(arene)(propene){sup +}, respectively. The extent to which displacement takes place depends on the nature of the original coordinated arene and is higher when it contains a CO group. With suitable free arenes as reagent gases, arene displacement is also observed, producing Cr(arene{prime}){sub 2}{sup +}. The formation of the disubstituted ions depends, once again, on the nature of the coordinated arene as well as on the relative bond energy of Cr{sup +}-arene{prime} with respect to Cr{sup +}-arene. CID experiments have been performed in order to obtain a sequence of relative binding energies of the arenes to Cr{sup +}. The results are consistent with the electronic and steric properties of the arene ligands, which affect the Cr{sup +}-arene bond strength.

  5. Ruthenium(II) polypyridyl complexes as mitochondria-targeted two-photon photodynamic anticancer agents.

    PubMed

    Liu, Jiangping; Chen, Yu; Li, Guanying; Zhang, Pingyu; Jin, Chengzhi; Zeng, Leli; Ji, Liangnian; Chao, Hui

    2015-07-01

    Clinical acceptance of photodynamic therapy is currently hindered by poor depth efficacy and inefficient activation of the cell death machinery in cancer cells during treatment. To address these issues, photoactivation using two-photon absorption (TPA) is currently being examined. Mitochondria-targeted therapy represents a promising approach to target tumors selectively and may overcome the resistance in current anticancer therapies. Herein, four ruthenium(II) polypyridyl complexes (RuL1-RuL4) have been designed and developed to act as mitochondria-targeted two-photon photodynamic anticancer agents. These complexes exhibit very high singlet oxygen quantum yields in methanol (0.74-0.81), significant TPA cross sections (124-198 GM), remarkable mitochondrial accumulation, and deep penetration depth. Thus, RuL1-RuL4 were utilized as one-photon and two-photon absorbing photosensitizers in both monolayer cells and 3D multicellular spheroids (MCSs). These Ru(II) complexes were almost nontoxic towards cells and 3D MCSs in the dark and generate sufficient singlet oxygen under one- and two-photon irradiation to trigger cell death. Remarkably, RuL4 exhibited an IC50 value as low as 9.6 μM in one-photon PDT (λirr = 450 nm, 12 J cm(-2)) and 1.9 μM in two-photon PDT (λirr = 830 nm, 800 J cm(-2)) of 3D MCSs; moreover, RuL4 is an order of magnitude more toxic than cisplatin in the latter test system. The combination of mitochondria-targeting and two-photon activation provides a valuable paradigm to develop ruthenium(II) complexes for PDT applications.

  6. Oxidation Reactions of Dithiocarbamate Complexes of Ruthenium(II).

    PubMed

    Leung, Wa-Hung; Chim, Joyce L. C.; Hou, Hongwei; Hun, Tom S. M.; Williams, Ian D.; Wong, Wing-Tak

    1997-09-24

    The reaction of Ru(Et(2)dtc)(2)(DMSO)(2) (Et(2)dtc = N,N-diethyldithiocarbamate; DMSO = dimethyl sulfoxide) with t-BuNC gave trans-Ru(Et(2)dtc)(2)(CN-t-Bu)(2), 1. Complex 1 crystallizes in the monoclinic space group P2(1)/n with a = 9.753(2) Å, b = 11.583(2) Å, c = 12.974(2) Å, and beta = 91.8(2) degrees for Z = 2. The crystal structure of 1 shows the trans disposition of the two isocyanides; the mean Ru-S and Ru-C distances are 2.409 and 1.977(2) Å, respectively. Treatment of [Ru(diene)Cl(2)](n)() with Na(Et(2)dtc) afforded Ru(Et(2)dtc)(2)(diene) (diene = bicyclo[2.2.1]hepta-2,5-diene (NBD), 2, 1,5-cyclooctadiene (COD), 3). Complex 2 crystallizes in the triclinic space group P&onemacr; with a = 7.316(1) Å, b = 10.346(1) Å, c = 15.123(2) Å, alpha = 103.69(2) degrees, beta = 93.54(2) degrees, and gamma = 100.61(2) degrees for Z = 2. The mean Ru-S and Ru-C distances in 2 are 2.416 and 2.137 Å, respectively. The reaction of cis-Ru(Et(2)dtc)(2)(CO)(2) with iodine gave the 2:1 molecular iodine complex cis-Ru(Et(2)dtc)(2)(CO)(2).(1)/(2)I(2) 4, which crystallizes in the monoclinic space group P2(1)/c with a = 7.347(2), b = 22.227(2) Å, c = 12.891(2) Å, and beta =95.98 (2) degrees for Z = 4. The mean Ru-S and Ru-C and the I-I distances in complex 4 are 2.427, 1.903, and 2.745(1) Å, respectively. Treatment of Ru(Et(2)dtc)(2)(DMSO)(2) with I(2) gave the linear Ru(II)-Ru(III)-Ru(III) trimer [Ru(3)(Et(2)dtc)(6)(DMSO)(2)](I(3))(2), 5, which crystallizes in the triclinic space group P&onemacr; with a = 14.125(3) Å, b = 20.829(6) Å, c = 13.658(3) Å, alpha = 97.57(2) degrees, beta = 110.01(2) degrees, and gamma = 71.25(2) degrees for Z = 2. The structure of complex 6 can be viewed as consisting of a {Ru(2)(III)(Et(2)dtc)(4)}(2+) core and a {Ru(II)(Et(2)dtc)(2)(DMSO)(2)} moiety, which are linked together via the two dithiocarbamate sulfurs of the latter. While the two Ru(III) centers are connected by a Ru-Ru single bond (Ru-Ru = 2.826(2) Å), there is no direct

  7. DNA interaction, antioxidant activity, and bioactivity studies of two ruthenium(II) complexes

    NASA Astrophysics Data System (ADS)

    Han, Bing-Jie; Jiang, Guang-Bin; Yao, Jun-Hua; Li, Wei; Wang, Ji; Huang, Hong-Liang; Liu, Yun-Jun

    2015-01-01

    Two new ruthenium(II) polypyridyl complexes [Ru(dmb)2(dcdppz)](ClO4)2 (1) and [Ru(bpy)2(dcdppz)](ClO4)2 (2) were prepared and characterized. The crystal structure of the complex 2 was solved by single crystal X-ray diffraction. The complex crystallizes in the monoclinic system, space group P21/n with a = 12.9622(14) Å, b = 17.1619(19) Å, c = 22.7210(3) Å, β = 100.930(2)°, R = 0.0536, Rω = 0.1111. The DNA-binding constants for complexes 1 and 2 were determined to be 1.92 × 105 (s = 1.72) and 2.24 × 105 (s = 1.86) M-1, respectively. The DNA-binding behaviors showed that complexes 1 and 2 interact with DNA by intercalative mode. The antioxidant activities of the ligand and the complexes were performed. Ligand, dcdppz, has no cytotoxicity against the selected cell lines. Complex 1 shows higher cytotoxicity than complex 2, but lower than cisplatin toward selected cell lines. The apoptosis and cell cycle arrest were investigated, and the apoptotic mechanism of BEL-7402 cells was studied by reactive oxygen species (ROS), mitochondrial membrane potential and western blot analysis. Complex 1 induces apoptosis in BEL-7402 cells through ROS-mediated mitochondrial dysfunction pathway and by regulating the expression of Bcl-2 family proteins.

  8. In vitro and in vivo activity and cross resistance profiles of novel ruthenium (II) organometallic arene complexes in human ovarian cancer

    PubMed Central

    Aird, R E; Cummings, J; Ritchie, A A; Muir, M; Morris, R E; Chen, H; Sadler, P J; Jodrell, D I

    2002-01-01

    Ruthenium complexes offer the potential of reduced toxicity, a novel mechanism of action, non-cross resistance and a different spectrum of activity compared to platinum containing compounds. Thirteen novel ruthenium(II) organometallic arene complexes have been evaluated for activity (in vitro and in vivo) in models of human ovarian cancer, and cross-resistance profiles established in cisplatin and multi-drug-resistant variants. A broad range of IC50 values was obtained (0.5 to >100 μM) in A2780 parental cells with two compounds (RM175 and HC29) equipotent to carboplatin (6 μM), and the most active compound (HC11) equipotent to cisplatin (0.6 μM). Stable bi-dentate chelating ligands (ethylenediamine), a more hydrophobic arene ligand (tetrahydroanthracene) and a single ligand exchange centre (chloride) were associated with increased activity. None of the six active ruthenium(II) compounds were cross-resistant in the A2780cis cell line, demonstrated to be 10-fold resistant to cisplatin/carboplatin by a mechanism involving, at least in part, silencing of MLH1 protein expression via methylation. Varying degrees of cross-resistance were observed in the P-170 glycoprotein overexpressing multi-drug-resistant cell line 2780AD that could be reversed by co-treatment with verapamil. In vivo activity was established with RM175 in the A2780 xenograft together with non-cross-resistance in the A2780cis xenograft and a lack of activity in the 2780AD xenograft. High activity coupled to non cross-resistance in cisplatin resistant models merit further development of this novel group of anticancer compounds. British Journal of Cancer (2002) 86, 1652–1657. DOI: 10.1038/sj/bjc/6600290 www.bjcancer.com © 2002 Cancer Research UK PMID:12085218

  9. Organometallic osmium(II) arene anticancer complexes containing picolinate derivatives.

    PubMed

    van Rijt, Sabine H; Peacock, Anna F A; Johnstone, Russell D L; Parsons, Simon; Sadler, Peter J

    2009-02-16

    Chlorido osmium(II) arene [(eta(6)-biphenyl)Os(II)(X-pico)Cl] complexes containing X = Br (1), OH (2), and Me (3) as ortho, or X = Cl (4), CO(2)H (5), and Me (6) as para substituents on the picolinate (pico) ring have been synthesized and characterized. The X-ray crystal structures of 1 and 6 show typical "piano-stool" geometry with intermolecular pi-pi stacking of the biphenyl outer rings of 6. At 288 K the hydrolysis rates follow the order 2 > 6 > 4 > 3 > 5 > 1 with half-lives ranging from minutes to 4.4 h illustrating the influence of both electronic and steric effects of the substituents. The pK(a) values of the aqua adducts 3A, 4A, 5A, and 6A were all in the range of 6.3-6.6. The para-substituted pico complexes 4-6 readily formed adducts with both 9-ethyl guanine (9EtG) and 9-ethyl adenine (9EtA), but these were less favored for the ortho-substituted complexes 1 and 3 showing little reaction with 9EtG and 9EtA, respectively. Density-functional theory calculations confirmed the observed preferences for nucleobase binding for complex 1. In cytotoxicity assays with A2780, cisplatin-resistant A2780cis human ovarian, A549 human lung, and HCT116 colon cancer cells, only complexes 4 (p-Cl) and 6 (p-Me) exhibited significant activity (IC(50) values < 25 microM). Both of these complexes were as active as cisplatin in A2780 (ovarian) and HCT116 (colon) cell lines, and even overcome cisplatin resistance in the A2780cis (ovarian) cell line. The inactivity of 5 is attributed to the negative charge on its para carboxylate substituent. These data illustrate how the chemical reactivity and cancer cell cytotoxicity of osmium arene complexes can be controlled and "fine-tuned" by the use of steric and electronic effects of substituents on a chelating ligand to give osmium(II) arene complexes which are as active as cisplatin but have a different mechanism of action.

  10. Arene C-H amination at nickel in terphenyl-diphosphine complexes with labile metal-arene interactions.

    PubMed

    Herbert, David E; Lara, Nadia C; Agapie, Theodor

    2013-11-25

    The meta-terphenyl diphosphine, m-P2, 1, was utilized to support Ni centers in the oxidation states 0, I, and II. A series of complexes bearing different substituents or ligands at Ni was prepared to investigate the dependence of metal-arene interactions on oxidation state and substitution at the metal center. Complex (m-P2)Ni (2) shows strong Ni(0)-arene interactions involving the central arene ring of the terphenyl ligand both in solution and the solid state. These interactions are significantly less pronounced in Ni(0) complexes bearing L-type ligands (2-L: L=CH3CN, CO, Ph2CN2), Ni(I)X complexes (3-X: X=Cl, BF4, N3, N3B(C6F5)3), and [(m-P2)Ni(II)Cl2] (4). Complex 2 reacts with substrates, such as diphenyldiazoalkane, sulfur ylides (Ph2 S=CH2 ), organoazides (RN3: R=para-C6H4OMe, para-C6H4CF3, 1-adamantyl), and N2O with the locus of observed reactivity dependent on the nature of the substrate. These reactions led to isolation of an η(1)-diphenyldiazoalkane adduct (2-Ph2CN2), methylidene insertion into a Ni-P bond followed by rearrangement of a nickel-bound phosphorus ylide (5) to a benzylphosphine (6), Staudinger oxidation of the phosphine arms, and metal-mediated nitrene insertion into an arene C-H bond of 1, all derived from the same compound (2). Hydrogen-atom abstraction from a Ni(I)-amide (9) and the resulting nitrene transfer supports the viability of Ni-imide intermediates in the reaction of 1 with 1-azido-arenes.

  11. Density functional theory studies of interactions of ruthenium-arene complexes with base pair steps.

    PubMed

    Mutter, Shaun T; Platts, James A

    2011-10-20

    Density functional theory (DFT) calculations have been performed to determine the strength and geometry of intermolecular interactions of "piano-stool" ruthenium arene complexes, which show potential as anticancer treatments. Model complexes with methane and benzene indicate that the coordinated arene has C-H···π acceptor ability similar to that of free benzene, whereas this arene acts as a much stronger C-H donor or partner in π-stacking than free benzene. The source of these enhanced interactions is identified as a combination of electrostatic and dispersion effects. Complexes of Ru-arene complexes with base-pair step fragments of DNA, in which the arene has the potential to act as an intercalator, have also been investigated. Binding energies are found to be sensitive to the size and nature of the arene, with larger and more flexible arenes having stronger binding. π-stacking and C-H···π interactions between arene and DNA bases and hydrogen bonds from coordinated N-H to DNA oxygen atoms, as well as covalent Ru-N bonding, contribute to the overall binding. The effect of complexation on DNA structure is also examined, with larger rise and more negative slide values than canonical B-DNA observed in all cases.

  12. A functional ruthenium(ii) complex for imaging biothiols in living bodies.

    PubMed

    Ye, Zhiqiang; Gao, Quankun; An, Xin; Song, Bo; Yuan, Jingli

    2015-05-01

    A unique ruthenium(ii) complex, [Ru(bpy)2(DNS-bpy)](PF6)2 [bpy: 2,2'-bipyridine, DNS-bpy: 4-(2,4-dinitrophenylthio)-2,2'-bipyridine], that can act as a probe for the recognition and luminescence sensing of biothiols has been designed and synthesized. Due to the presence of effective photo-induced electron transfer (PET) from the potent electron donor (Ru-bpy centre) to the strong electron acceptor (2,4-dinitrophenyl moiety), the Ru(ii) complex itself is weakly luminescent. Reaction of [Ru(bpy)2(DNS-bpy)](PF6)2 with biothiols leads to the replacement of the 2,4-dinitrophenyl moiety by biothiols, which results in the loss of PET within the complex, to allow recovery of the MLCT-based emission of the Ru(ii) complex with an 80-fold increase in luminescence intensity. Taking advantage of the high specificity and sensitivity, and the excellent photophysical properties of Ru(ii) complexes, [Ru(bpy)2(DNS-bpy)](PF6)2 was successfully applied to the luminescence imaging of biothiols in living Daphnia magna. The results demonstrated the practical applicability of [Ru(bpy)2(DNS-bpy)](PF6)2 as a luminescent probe for the monitoring of biothiols in living bodies.

  13. Structures and photoactivation of charge-transfer complexes of bis(arene)iron(II) dications with ferrocene and arene donors

    SciTech Connect

    Lehmann, R.E.; Kochi, J.K. )

    1991-01-16

    Ferrocene forms a series of unusual charge-transfer crystals with the isoelectronic bis(arene)iron(II) dication, in which X-ray crystallography establishes the alternate (heterosoric) stacking of sandwich structures comprising the donor-acceptor pairs. In acetonitrile, the 1:1 complex (Cp{sub 2}Fe, Ar{sub 2}Fe{sup 2+}) shows a broad absorption band centered at {lambda}{sub max} {approximately} 630 nm. Bis(arene)iron(II) acceptors also form highly colored crystals with various arene donors, in which the charge-transfer absorption (hv{sub CT}) derives from the same heterosoric stacking of donor-acceptor pairs-despite the structurally divergent nature of the arene (planar) and ferrocene (sandwich) donors. These absorptions undergo a predictable red-shift with increasing acceptor strength in the order (BZ){sub 2}Fe{sup 2+} > (MES){sub 2}Fe{sup 2+} > (DUR){sub 2}Fe{sup 2+} > (HMB){sub 2}Fe{sup 2+}, as judged by the reduction potentials E {sub red} of the benzene, mesitylene, durene, and hexamethylbenzene derivatives, respectively.

  14. Amphoteric calix[8]arene-based complex for pH-triggered drug delivery.

    PubMed

    Xue, Yan; Guan, Yong; Zheng, Anna; Xiao, Huining

    2013-01-01

    Amphoteric calix[8]arene with negatively charged upper rim and positively charged lower rim was synthesized based on water-soluble p-sulfonato-calix[8]arene. The pH-sensitive amphoteric calix[8]arenes exhibit not only a good hydrophobic drug loading capacity but also a pH-triggered drug releasing behavior. The in vitro release studies demonstrated that release of ciprofloxacin from amphoteric calix[8]arene complexes was highly pH-sensitive. More efficient drug release was observed at mildly acidic pH 5.0 and basic pH 8.5 compared to physiological pH. The amphoteric calix[8]arene complexes hold out great promise of being pH-sensitive drug carrier.

  15. Interligand electron transfer in heteroleptic ruthenium(II) complexes occurs on multiple time scales.

    PubMed

    Stark, Charles W; Schreier, Wolfgang J; Lucon, Janice; Edwards, Ethan; Douglas, Trevor; Kohler, Bern

    2015-05-21

    The time-dependent localization of the metal-to-ligand charge transfer (MLCT) excited states of ruthenium(II) complexes containing 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen) ligands was studied by femtosecond transient absorption spectroscopy. Time-resolved anisotropy measurements indicate that the excited state hops randomly among the three ligands of each complex by subpicosecond interligand electron transfer (ILET). Although the bpy- and phen-localized (3)MLCT states have similar energies and steady-state emission spectra, pronounced differences in their excited-state absorption spectra make it possible to observe changes in excited state populations using magic angle transient absorption measurements. Analysis of the magic angle signals shows that the excited electron is equally likely to be found on any of the three ligands approximately 1 ps after excitation, but this statistical distribution subsequently evolves to a Boltzmann distribution with a time constant of approximately 10 ps. The apparent contradiction between ultrafast ILET revealed by time-dependent anisotropy measurements and the slower ILET seen in magic angle measurements on the tens of picoseconds time scale is explained by a model in which the underlying rates depend dynamically on excess vibrational energy. The insight that ILET can occur over multiple time scales reconciles contradictory literature observations and may lead to improved photosensitizer performance.

  16. Carbon nanotubes dispersed in aqueous solution by ruthenium(ii) polypyridyl complexes

    NASA Astrophysics Data System (ADS)

    Huang, Kewei; Saha, Avishek; Dirian, Konstantin; Jiang, Chengmin; Chu, Pin-Lei E.; Tour, James M.; Guldi, Dirk M.; Martí, Angel A.

    2016-07-01

    Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs. These studies show that the photoluminescence of both, that is, of the ruthenium complexes and of SWCNTs, are quenched when they interact with each other. Pump-probe transient absorption experiments were performed to shed light onto the nature of the photoluminescence quenching, showing carbon nanotube-based bands with picosecond lifetimes, but no new bands which could be unambigously assigned to photoinduced charge transfer process. Thus, from the spectroscopic data, we conclude that quenching of the photoluminescence of the ruthenium complexes is due to energy transfer to proximal SWCNTs.Cationic ruthenium(ii) polypyridyl complexes with appended pyrene groups have been synthesized and used to disperse single-walled carbon nanotubes (SWCNT) in aqueous solutions. To this end, planar pyrene groups enable association by means of π-stacking onto carbon nanotubes and, in turn, the attachment of the cationic ruthenium complexes. Importantly, the ionic nature of the ruthenium complexes allows the formation of stable dispersions featuring individualized SWCNTs in water as confirmed in a number of spectroscopic and microscopic assays. In addition, steady-state photoluminescence spectroscopy was used to probe the excited state interactions between the ruthenium complexes and SWCNTs

  17. A brief overview of the structural determination of cyclopentadienyliron arene complexes

    NASA Astrophysics Data System (ADS)

    Abd-El-Aziz, Alaa S.

    1997-03-01

    This article constitutes a brief overview of the use of NMR spectroscopy for the determination of the structure of a number of cyclopentadienyliron arene systems. The examples presented here demonstrate the use of one- and two-dimensional NMR techniques in predicting the chemical structure and dynamics of these complexes. The numerous isomers obtained from the hydride addition to mono- and dicyclopentadienyliron arene complexes were identified using 2D HH COSY and CH COSY. The 2D 1H COSY, DQ-COSY and NOE study of the ( η6-2,6-dimethylphenyl)-phenylsulphonylacetonitrile- η5-cyclopentadienyliron cation showed that there is restricted rotation about the arene-methine carbon bond. 1D NMR was also used for the determination of the diastereomeric nature of the arene complexes, which arose from their complexation to the cyclopenta-dienyliron moieties, as well as in estimating the number of repeating units in the oligomeric complexes.

  18. Cellular delivery of pyrenyl-arene ruthenium complexes by a water-soluble arene ruthenium metalla-cage.

    PubMed

    Furrer, Mona Anca; Schmitt, Frédéric; Wiederkehr, Michaël; Juillerat-Jeanneret, Lucienne; Therrien, Bruno

    2012-06-28

    Three pyrenyl-arene ruthenium complexes (M(1)-M(3)) of the general formula [Ru(η(6)-arene-pyrenyl)Cl(2)(pta)] (pta = 1,3,5-triaza-7-phosphaadamantane) have been synthesised and characterised. Prior to the coordination to ruthenium, pyrene was connected to the arene ligand via an alkane chain containing different functional groups: ester (L(1)), ether (L(2)) and amide (L(3)), respectively. Furthermore, the pyrenyl moieties of the M(n) complexes were encapsulated within the hydrophobic cavity of the water soluble metalla-cage, [Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+) (tpt = 2,4,6-tri-(pyridin-4-yl)-1,3,5-triazine; donq = 5,8-dioxydo-1,4-naphthoquinonato), while the arene ruthenium end was pointing out of the cage, thus giving rise to the corresponding host-guest systems [M(n)⊂Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+) ([M(n)⊂cage](6+)). The antitumor activity of the pyrenyl-arene ruthenium complexes (M(n)) and the corresponding host-guest systems [M(n)⊂cage][CF(3)SO(3)](6) were evaluated in vitro in different types of human cancer cell lines (A549, A2780, A2780cisR, Me300 and HeLa). Complex M(2), which contains an ether group within the alkane chain, demonstrated at least a 10 times higher cytotoxicity than the reference compound [Ru(η(6)-p-cymene)Cl(2)(pta)] (RAPTA-C). All host-guest systems [M(n)⊂cage](6+) showed good anticancer activity with IC(50) values ranging from 2 to 8 μM after 72 h exposure. The fluorescence of the pyrenyl moiety allowed the monitoring of the cellular uptake and revealed an increase of uptake by a factor two of the M(2) complex when encapsulated in the metalla-cage [Ru(6)(η(6)-p-cymene)(6)(tpt)(2)(donq)(3)](6+).

  19. Titania modification with a ruthenium(II) complex and gold nanoparticles for photocatalytic degradation of organic compounds.

    PubMed

    Zheng, Shuaizhi; Wei, Zhishun; Yoshiiri, Kenta; Braumüller, Markus; Ohtani, Bunsho; Rau, Sven; Kowalska, Ewa

    2016-01-01

    Titania of fine anatase nanoparticles (ST01) was modified successively with two components, i.e., a ruthenium(II) complex with phosphonic anchoring groups [Ru(bpy)2(4,4'-(CH2PO3H2)2bpy)](2+) bpy = 2,2'-bipyridine (Ru(II)CP) and gold nanoparticles (Au). Various compositions of two titania modifiers were investigated, i.e., Au, Au + Ru(II)CP, Au + 0.5Ru(II)CP, Ru(II)CP, 0.5Ru(II)CP and 0.25Ru(II)CP, where Au and Ru(II)CP correspond to 0.81 mol% and 0.34 mol% (with respect to titania), respectively. In the case of hybrid photocatalysts, the sequence of modification (ruthenium(II) complex adsorption or gold deposition) was investigated to check its influence on the resultant properties and thus photocatalytic performance. Diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) were applied to characterize the structural properties of the prepared photocatalysts, which confirmed the successful introduction of modifiers of the ruthenium(II) complex and/or gold NPs. Different distributions of gold particle sizes and chemical compositions were obtained for the hybrid photocatalysts prepared with an opposite sequence. It was found that photocatalytic activities depended on the range of used irradiation (UV/vis or vis) and the kind of modifier in different ways. Gold NPs improved the photocatalytic activities, while Ru(II)CP inhibited the reactions under UV/vis irradiation, i.e., methanol dehydrogenation and acetic acid degradation. Oppositely, Ru(II)CP greatly enhanced the photocatalytic activities for 2-propanol oxidation under visible light irradiation. PMID:26661372

  20. Dinuclear Ruthenium(II) Complexes as Two-Photon, Time-Resolved Emission Microscopy Probes for Cellular DNA**

    PubMed Central

    Baggaley, Elizabeth; Gill, Martin R; Green, Nicola H; Turton, David; Sazanovich, Igor V; Botchway, Stanley W; Smythe, Carl; Haycock, John W; Weinstein, Julia A; Thomas, Jim A

    2014-01-01

    The first transition-metal complex-based two-photon absorbing luminescence lifetime probes for cellular DNA are presented. This allows cell imaging of DNA free from endogenous fluorophores and potentially facilitates deep tissue imaging. In this initial study, ruthenium(II) luminophores are used as phosphorescent lifetime imaging microscopy (PLIM) probes for nuclear DNA in both live and fixed cells. The DNA-bound probes display characteristic emission lifetimes of more than 160 ns, while shorter-lived cytoplasmic emission is also observed. These timescales are orders of magnitude longer than conventional FLIM, leading to previously unattainable levels of sensitivity, and autofluorescence-free imaging. PMID:24458590

  1. Functionalized O6-Corona[6]arenes: Synthesis, Structure, and Fullerene Complexation Property.

    PubMed

    Ren, Wen-Sheng; Zhao, Liang; Wang, Mei-Xiang

    2016-07-01

    The synthesis, structure, and fullerene complexation property of novel and functionalized On-corona[n]arenes were reported. Based on the fragment coupling strategy, ester-containing On-corona[n]arenes (n = 6, 8) were obtained readily starting from 1,4-hydroquinone and diethyl 2,5-difluoroterephthalate. Reduction of esters with LiAlH4 produced almost quantitatively hydroxymethylated On-corona[n]arenes, which underwent etherification with MeI to afford methoxymethyl-substituted On-corona[n]arenes (n = 6, 8) in good yields. The macrocycles adopt unique corona-type conformation with a large cylindroid cavity. They are strong macrocyclic host molecules to form 1:1 complexes with fullerenes C60 and C70 in toluene with an associate constant up to (1.59 ± 0.04) × 10(5) M(-1).

  2. Functionalized O6-Corona[6]arenes: Synthesis, Structure, and Fullerene Complexation Property.

    PubMed

    Ren, Wen-Sheng; Zhao, Liang; Wang, Mei-Xiang

    2016-07-01

    The synthesis, structure, and fullerene complexation property of novel and functionalized On-corona[n]arenes were reported. Based on the fragment coupling strategy, ester-containing On-corona[n]arenes (n = 6, 8) were obtained readily starting from 1,4-hydroquinone and diethyl 2,5-difluoroterephthalate. Reduction of esters with LiAlH4 produced almost quantitatively hydroxymethylated On-corona[n]arenes, which underwent etherification with MeI to afford methoxymethyl-substituted On-corona[n]arenes (n = 6, 8) in good yields. The macrocycles adopt unique corona-type conformation with a large cylindroid cavity. They are strong macrocyclic host molecules to form 1:1 complexes with fullerenes C60 and C70 in toluene with an associate constant up to (1.59 ± 0.04) × 10(5) M(-1). PMID:27324274

  3. Cyclometalated ruthenium(II) complexes as efficient redox mediators in peroxidase catalysis.

    PubMed

    Alpeeva, Inna S; Soukharev, Valentin S; Alexandrova, Larissa; Shilova, Nadezhda V; Bovin, Nicolai V; Csöregi, Elisabeth; Ryabov, Alexander D; Sakharov, Ivan Yu

    2003-07-01

    Cyclometalated ruthenium(II) complexes, [Ru(II)(C~N)(N~N)(2)]PF(6) [HC~N=2-phenylpyridine (Hphpy) or 2-(4'-tolyl)pyridine; N~N=2,2'-bipyridine, 1,10-phenanthroline, or 4,4'-dimethyl-2,2'-bipyridine], are rapidly oxidized by H(2)O(2) catalyzed by plant peroxidases to the corresponding Ru(III) species. The commercial isoenzyme C of horseradish peroxidase (HRP-C) and two recently purified peroxidases from sweet potato (SPP) and royal palm tree (RPTP) have been used. The most favorable conditions for the oxidation have been evaluated by varying the pH, buffer, and H(2)O(2) concentrations and the apparent second-order rate constants ( k(app)) have been measured. All the complexes studied are oxidized by HRP-C at similar rates and the rate constants k(app) are identical to those known for the best substrates of HRP-C (10(6)-10(7) M(-1) s(-1)). Both cationic (HRP-C) and anionic (SPP and RPTP) peroxidases show similar catalytic efficiency in the oxidation of the Ru(II) complexes. The mediating capacity of the complexes has been evaluated using the SPP-catalyzed co-oxidation of [Ru(II)(phpy)(bpy)(2)]PF(6) and catechol as a poor peroxidase substrate as an example. The rate of enzyme-catalyzed oxidation of catechol increases more than 10000-fold in the presence of the ruthenium complex. A simple routine for calculating the rate constant k(c) for the oxidation of catechol by the Ru(III) complex generated enzymatically from [Ru(II)(phpy)(bpy)(2)](+) is proposed. It is based on the accepted mechanism of peroxidase catalysis and involves spectrophotometric measurements of the limiting Ru(II) concentration at different concentrations of catechol. The calculated k(c) value of 0.75 M(-1) s(-1) shows that the cyclometalated Ru(II) complexes are efficient mediators in peroxidase catalysis. PMID:12774217

  4. Preparation, spectroscopy, EXAFS, electrochemistry and pharmacology of new ruthenium(II) carbonyl complexes containing ferrocenylthiosemicarbazone and triphenylphosphine/arsine

    NASA Astrophysics Data System (ADS)

    Prabhakaran, R.; Anantharaman, S.; Thilagavathi, M.; Kaveri, M. V.; Kalaivani, P.; Karvembu, R.; Dharmaraj, N.; Bertagnolli, H.; Dallemer, F.; Natarajan, K.

    2011-02-01

    A new series of new hetero-bimetallic complexes containing iron and ruthenium of the general formula [RuCl(CO)(B)(EPh 3)(L)] (where E = P or As; B = PPh 3, AsPh 3, py or pip; L = ferrocene derived monobasic bidentate thiosemicarbazone ligand) have been synthesized by the reaction between ferrocene-derived thiosemicarbazones and ruthenium(II) complexes of the type [RuHCl(CO)(B)(EPh 3) 2] (where E = P or As; B = PPh 3, AsPh 3, py or pip). The new complexes have been characterized by elemental analyses, IR, electronic, NMR ( 1H, 13C and 31P), EXAFS (extended X-ray absorption fine structure spectroscopy) and cyclic voltammetric techniques. Antibacterial activity of the new complexes has been screened against Escherichia coli, Vibrio cholerae, and Pseudomonas aeruginosa species.

  5. Synthesis, DNA binding and photocleavage, and cellular uptake of an alkyl chain-linked dinuclear ruthenium(II) complex.

    PubMed

    Liu, Ping; Liu, Jin; Zhang, Yu-Qi; Wu, Bao-Yan; Wang, Ke-Zhi

    2015-02-01

    A dinuclear ruthenium(II) complex [(bpy)2Ru(L(1))Ru(bpy)2]Cl4 {bpy=2,2'-bipyridine, L(1)=1,6-bis(3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-9H-carbazol-9-yl)hexane} was synthesised and characterized. The calf thymus DNA (ct-DNA) binding properties of the complex were investigated by means of UV-Visible absorption and emission spectrophotometric titrations, ethidium bromide competitive binding, steady-state emission quenching with ferrocyanide, DNA viscosity measurements, and DNA thermal denaturation. The results indicated that the complex avidly binds to ct-DNA most probably through a threading bis-intercalative mode. The complex was also evidenced to act as an efficient DNA photocleaver, and an effective luminescent stain for cytoplasmic of HeLa cells with low cytotoxicity.

  6. μ-η6,η6-Arene-bridged diuranium hexakisketimide complexes isolable in two states of charge.

    PubMed

    Diaconescu, Paula L; Cummins, Christopher C

    2012-03-01

    Diuranium μ-η(6),η(6)-arene complexes supported by ketimide ligands were synthesized and characterized. Disodium or dipotassium salts of the formula M(2)(μ-η(6),η(6)-arene)[U(NC(t)BuMes)(3)](2) (M = Na or K, Mes = 2,4,6-C(6)H(2)Me(3)) and monopotassium salts of the formula K(μ-η(6),η(6)-arene)[U(NC(t)BuMes)(3)](2) (arene = naphthalene, biphenyl, trans-stilbene, or p-terphenyl) were both observed. Two different salts of the monoanionic, toluene-bridged complexes are also described. Density functional theory calculations have been employed to illuminate the electronic structure of the μ-η(6),η(6)-arene diuranium complexes and to facilitate the comparison with related transition-metal systems, in particular (μ-η(6),η(6)-C(6)H(6))[VCp](2). It was found that the μ-η(6),η(6)-arene diuranium complexes were isolobal with (μ-η(6),η(6)-C(6)H(6))[VCp](2) and that the principal arene-binding interaction was a pair of δ bonds (total of 4e) involving both metals and the arene lowest unoccupied molecular orbital. Reactivity studies have been carried out with the mono- and dianionic μ-η(6),η(6)-arene diuranium complexes, revealing contrasting modes of redox chemistry as a function of the system's state of charge.

  7. Electrochemical DNA biosensor for detection of porcine oligonucleotides using ruthenium(II) complex as intercalator label redox

    NASA Astrophysics Data System (ADS)

    Halid, Nurul Izni Abdullah; Hasbullah, Siti Aishah; Ahmad, Haslina; Heng, Lee Yook; Karim, Nurul Huda Abd; Harun, Siti Norain

    2014-09-01

    A DNA biosensor detection of oligonucleotides via the interactions of porcine DNA with redox active complex based on the electrochemical transduction is described. A ruthenium(II) complex, [Ru(bpy)2(PIP)]2+, (bpy = 2,2'bipyridine, PIP = 2-phenylimidazo[4,5-f[[1,10-phenanthroline]) as DNA label has been synthesized and characterized by 1H NMR and mass spectra. The study was carried out by covalent bonding immobilization of porcine aminated DNA probes sequences on screen printed electrode (SPE) modified with succinimide-acrylic microspheres and [Ru(bpy)2(PIP)]2+ was used as electrochemical redox intercalator label to detect DNA hybridization event. Electrochemical detection was performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the potential range where the ruthenium (II) complex was active. The results indicate that the interaction of [Ru(bpy)2(PIP)]2+ with hybridization complementary DNA has higher response compared to single-stranded and mismatch complementary DNA.

  8. Experimental and theoretical studies on arene-bridged metal-metal-bonded dimolybdenum complexes.

    PubMed

    Carrasco, Mario; Curado, Natalia; Álvarez, Eleuterio; Maya, Celia; Peloso, Riccardo; Poveda, Manuel L; Rodríguez, Amor; Ruiz, Eliseo; Álvarez, Santiago; Carmona, Ernesto

    2014-05-12

    The bis(hydride) dimolybdenum complex, [Mo2(H)2{HC(N-2,6-iPr2C6H3)2}2(thf)2], 2, which possesses a quadruply bonded Mo2(II) core, undergoes light-induced (365 nm) reductive elimination of H2 and arene coordination in benzene and toluene solutions, with formation of the Mo(I)2 complexes [Mo2{HC(N-2,6-iPr2C6H3)2}2(arene)], 3⋅C6H6 and 3⋅C6H5Me, respectively. The analogous C6H5OMe, p-C6H4Me2, C6H5F, and p-C6H4F2 derivatives have also been prepared by thermal or photochemical methods, which nevertheless employ different Mo2 complex precursors. X-ray crystallography and solution NMR studies demonstrate that the molecule of the arene bridges the molybdenum atoms of the Mo(I)2 core, coordinating to each in an η(2) fashion. In solution, the arene rotates fast on the NMR timescale around the Mo2-arene axis. For the substituted aromatic hydrocarbons, the NMR data are consistent with the existence of a major rotamer in which the metal atoms are coordinated to the more electron-rich C-C bonds.

  9. Trinuclear Nickel Complexes with Metal-Arene Interactions Supported by Tris- and Bis(phosphinoaryl)benzene Frameworks

    PubMed Central

    Suseno, Sandy; Horak, Kyle T.; Day, Michael W.; Agapie, Theodor

    2014-01-01

    Triphosphine and diphosphine ligands with backbones designed to facilitate metal-arene interactions were employed to support multinuclear Ni complexes. Di- and trinuclear metal complexes supported by a triphosphine containing a triarylbenzene linker display diverse metal-arene binding modes. Multinuclear Ni halide complexes were isolated with strongly interacting metal centers bound to opposite faces of the coordinated arene. Upon reaction of the trinickel diiodide complex, 2, with disodium tetracarbonylferrate, a cofacial triangulo nickel(0) complex, 4, was isolated. The Ni03 cluster motif can also be supported by a para-terphenyldiphosphine, where a terminal carbon monoxide ligand replaces the third phosphine donor. All multinuclear complexes feature strong metal-arene interactions, demonstrating the use of an arene as a versatile ligand design element for small clusters. PMID:24532865

  10. Arene complexes of transition metals in reactions with nucleophilic reagents. XVI. Kinetics and mechanism of the reaction of the. pi. -arene complexes of chromium and iron and piperidine

    SciTech Connect

    Oleinik, I.I.; Kun, P.P.; Litvak, V.V.; Shteingarts, V.D.

    1988-05-20

    The kinetics of the reaction of ..pi..-arene complexes of the (/eta/-XC/sub 6/H/sub 4/Cl)ML type (where ML = Cr(CO)/sub 3/ (X = p-Cl), Cr/sup +/(/eta/-C/sub 6/H/sub 5/Cl) (X = H), Fe/sup +/(/eta/-C/sub 5/H/sub 5/) (X = H)) with piperidine in acetone suggest that in the second and third cases the controlling stage is the transformation of the intermediate sigma complex into the reaction products almost entirely by a path with catalysis by the reagent while in the first case it is the formation of the intermediate. The marked increase in the catalytic effect of piperidine in the transition from neutral to cationic ..pi..-arene complexes show that the charge of the metal-complex fragment, coordinated with the arene, has a significant effect on the ratio of the rates of transformation of the intermediate sigma complex into the initial compounds and the final reaction products.

  11. Arene-ruthenium(II) complexes with hydrophilic P-donor ligands: versatile catalysts in aqueous media.

    PubMed

    Crochet, Pascale; Cadierno, Victorio

    2014-09-01

    In the last few years there has been increasing interest in the use of water as a reaction medium for catalysis, and therefore in designing water-soluble transition-metal catalysts. Half-sandwich (η(6)-arene)-ruthenium(ii) complexes are a versatile and well-known family of ruthenium compounds that exhibit a rich catalytic and coordination chemistry. This Perspective article focuses on the catalytic applications in aqueous media of (η(6)-arene)-ruthenium(ii) complexes containing water-soluble phosphines, and related hydrophilic P-donor ligands.

  12. A dinuclear ruthenium(II) complex as turn-on luminescent probe for hypochlorous acid and its application for in vivo imaging

    PubMed Central

    Liu, Zonglun; Gao, Kuo; Wang, Beng; Yan, Hui; Xing, Panfei; Zhong, Chongmin; Xu, Yongqian; Li, Hongjuan; Chen, Jianxin; Wang, Wei; Sun, Shiguo

    2016-01-01

    A dinuclear ruthenium(II) complex Ruazo was designed and synthesized, in which oxidative cyclization of the azo and o-amino group was employed for the detection of hypochlorous acid (HClO) in aqueous solution. The non-emissive Ruazo formed highly luminescent triazole-ruthenium(II) complex in presence of HClO and successfully imaged HClO in living cell and living mouse. PMID:27356618

  13. A dinuclear ruthenium(II) complex as turn-on luminescent probe for hypochlorous acid and its application for in vivo imaging

    NASA Astrophysics Data System (ADS)

    Liu, Zonglun; Gao, Kuo; Wang, Beng; Yan, Hui; Xing, Panfei; Zhong, Chongmin; Xu, Yongqian; Li, Hongjuan; Chen, Jianxin; Wang, Wei; Sun, Shiguo

    2016-06-01

    A dinuclear ruthenium(II) complex Ruazo was designed and synthesized, in which oxidative cyclization of the azo and o-amino group was employed for the detection of hypochlorous acid (HClO) in aqueous solution. The non-emissive Ruazo formed highly luminescent triazole-ruthenium(II) complex in presence of HClO and successfully imaged HClO in living cell and living mouse.

  14. Cation-mediated conversion of the state of charge in uranium arene inverted-sandwich complexes.

    PubMed

    Camp, Clément; Mougel, Victor; Pécaut, Jacques; Maron, Laurent; Mazzanti, Marinella

    2013-12-16

    Two new arene inverted-sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (3) and [K2{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (4) were synthesized by the reduction of the parent arene-bridged complex [{U(OSi(OtBu)3)3}2(μ-η(6):η(6)-C7H8)] (2) with stoichiometric amounts of KC8 yielding a rare family of inverted-sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high-valent uranium centers bridged by a reduced tetra-anionic toluene with the best formulation being U(V)-(arene(4-))-U(V), KU(IV)-(arene(4-))-U(V), and K2U(IV)-(arene(4-))-U(IV) for complexes 2, 3, and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the U(IV) mononuclear complex [U(OSi(OtBu)3)3(OTf)(thf)2] (5). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes.

  15. Investigations of thermal and photochemical arene displacement reactions from ruthenium and osmium arene complexes. 2. Photochemical carbon-hydrogen bond activation via the photolysis of iridium(III) azide and oxalate complexes

    SciTech Connect

    Freedman, D.A.

    1992-01-01

    The syntheses of several new bis-arene Ru(II) complexes are described. Complexes where one arene is naphthalene, anthracene or tetracene react thermally with acetonitrile resulting in arene displacement. Thermally inert complexes will react photochemically with acetonitrile. Kinetic data were collected for the chemical reactions and reaction mechanism are proposed. Electrochemical and spectroelectrochemical data are reported for the new hexacoordinate osmium complexes. Two methods of catalyzing the photochemical displacement of benzene from [CpOsBz][sup +] in acetonitrile to give [CpOs(CH[sub 3]CN)[sub 3

  16. Complex polycyclic scaffolds by metathesis rearrangement of Himbert arene/allene cycloadducts.

    PubMed

    Lam, Jonathan K; Schmidt, Yvonne; Vanderwal, Christopher D

    2012-11-01

    The intramolecular arene/allene cycloaddition first described 30 years ago by Himbert and Henn permits rapid access to strained polycyclic compounds. Alkene metathesis processes cleanly rearrange appropriately substituted cycloadducts into complex, functional-group-rich polycyclic lactams of potential utility for natural product synthesis and medicinal chemistry.

  17. New ruthenium(II) carbonyl complexes bearing disulfide Schiff base ligands and their applications as catalyst for some organic transformations

    NASA Astrophysics Data System (ADS)

    Prakash, Govindan; Viswanathamurthi, Periasamy

    2014-08-01

    Schiff base disulfide ligands (H2L1-6) were synthesized from the condensation of cystamine with salicylaldehyde(H2L1), 5-chlorosalicylaldehyde(H2L2), o-vanillin(H2L3), 2-hydroxyacetophenone(H2L4), 3-methyl-2-hydroxyacetophenone(H2L5), and 2-hydroxy-1-naphthaldehyde(H2L6). H2L1-6 reacts with the ruthenium precursor complex [RuHCl(CO)(PPh3)3] in benzene giving rise to six new ruthenium(II) complexes of general formula [Ru(CO)L1-6]. Characterization of the new complexes was carried out by using elemental and spectral (IR, UV-Vis, NMR (1H and 13C) and Mass) techniques. An octahedral geometry was assigned for all the complexes based on the spectral data obtained. The catalytic efficiency of the new complexes in aldehyde to amide conversion in the presence of NaHCO3, N-alkylation of aniline in the presence of t-BuOK, and transfer hydrogenation of ketones in the presence of iPrOH/KOH reactions were studied. Furthermore, the effect of solvents and catalyst/substrate ratio on the catalytic aldehyde to amide conversion were also discussed.

  18. New ruthenium(II) carbonyl complexes bearing disulfide Schiff base ligands and their applications as catalyst for some organic transformations.

    PubMed

    Prakash, Govindan; Viswanathamurthi, Periasamy

    2014-08-14

    Schiff base disulfide ligands (H2L(1-6)) were synthesized from the condensation of cystamine with salicylaldehyde(H2L(1)), 5-chlorosalicylaldehyde(H2L(2)), o-vanillin(H2L(3)), 2-hydroxyacetophenone(H2L(4)), 3-methyl-2-hydroxyacetophenone(H2L(5)), and 2-hydroxy-1-naphthaldehyde(H2L(6)). H2L(1-6) reacts with the ruthenium precursor complex [RuHCl(CO)(PPh3)3] in benzene giving rise to six new ruthenium(II) complexes of general formula [Ru(CO)L(1-6)]. Characterization of the new complexes was carried out by using elemental and spectral (IR, UV-Vis, NMR ((1)H and (13)C) and Mass) techniques. An octahedral geometry was assigned for all the complexes based on the spectral data obtained. The catalytic efficiency of the new complexes in aldehyde to amide conversion in the presence of NaHCO3, N-alkylation of aniline in the presence of t-BuOK, and transfer hydrogenation of ketones in the presence of iPrOH/KOH reactions were studied. Furthermore, the effect of solvents and catalyst/substrate ratio on the catalytic aldehyde to amide conversion were also discussed.

  19. Optimization of conditions for the determination of boron by a ruthenium(II) complex having diol moiety: A mechanistic study.

    PubMed

    Nakano, Eiko; Iwatsuki, Satoshi; Inamo, Masahiko; Takagi, Hideo D; Ishihara, Koji

    2008-01-15

    Two ruthenium(II) complexes, [Ru(bpy)(2)(dhbpy-H(-1))](+) and [Ru(bpy)(2)(dhphen)](2+) (bpy=2,2'-bipyridine, dhbpy=3,3'-dihydroxy-2,2'-bipyridine, dhphen=5,6-dihydroxy-1,10-phenanthroline) were examined for use as a colorimetric reagent for the determination of boron. The reactions of boric acid with these two complexes were thermodynamically and kinetically studied in detail in order to specify the reactive species and to set up optimum condition for the determination of boron. The detailed analysis of the kinetic data for the reaction of the latter water-soluble complex showed that both boric acid and borate ion were reactive in an alkaline solution. The thermodynamically and kinetically optimum pH for the determination of boron was ca. 9 at 25 degrees C. A spectrofluorimetric determination of boron with the latter complex was attempted at 600nm with excitation at 360nm, and at pH 8.9 using CHES (N-cyclohexyl-2-aminoethanesulfonic acid) buffer. It was found that a trace amount of boron as low as ca. 2x10(-5)M ( approximately 1ppm) could be detectable.

  20. Kinetics and mechanism of arene displacement in (eta-arene)dicarbonyl(chalcocarbonyl)chromium(0) complexes, (eta-arene)Cr(CO)/sub 2/(CX) (X = S, Se), by tertiary phosphites

    SciTech Connect

    Butler, I.S.; Ismail, A.A.

    1986-10-22

    The kinetics and mechanism of the arene substitution reactions of the chalcocarbonyl complexes (eta-arene)Cr(CO)/sub 2/(CX) (X = S, arene = C/sub 6/H/sub 6/, PhMe, PhNMe/sub 2/, PhCO/sub 2/Me, o-C/sub 6/H/sub 4/Me/sub 2/, m-C/sub 6/H/sub 4/(CO/sub 2/Me)Me, p-C/sub 6/H/sub 4/(CO/sub 2/Me)/sub 2/, p-C/sub 6/H/sub 4/(OMe)/sub 2/, 1,3,5-C/sub 6/H/sub 3/Me/sub 3/; X = Se, arene = C/sub 6/H/sub 6/) by tertiary phosphites (L = (MeO)/sub 3/P, (PhO)/sub 3/P, (C/sub 6/H/sub 11/O)/sub 3/P) in methylcyclohexane to form mer-Cr(CO)/sub 2/(CX)L/sub 3/ have been investigated. The reactions are significantly faster than those for the corresponding tricarbonyl complexes and are first-order in both substrate and entering ligand L. Activation parameters for arene = C/sub 6/H/sub 6/ and L = (MeO)/sub 3/P: X = S, ..delta..H/sup double dagger/ = 74.1 kJ mol/sup -1/, ..delta..S/sup double dagger/ = -117 J mol/sup -1/ deg/sup -1/; X = Se, ..delta..H/sup double dagger/ = 74.9 kJ mol/sup -1/, ..delta..S/sup double dagger/ = -100 J mol/sup -1/ deg/sup -1/. A mechanism involving the slight slippage of the arene ring from eta/sup 6/- to eta/sup x/-coordination (6 > x > 4) prior to entry of the first L ligand in the rate-determining step is proposed. The greater reactivity of the thio- and selenocarbonyl derivatives compared to that of the tricarbonyl analogues is attributed to the better ..pi..-acceptor capacities of CS and CSe compared to that of CO, resulting in weaker bonding between the Cr metal and the arene. Also, on the basis of this kinetic study, it appears likely that the thio- and selenocarbonyl complexes will not be as good catalysts as the (eta-arene)chromium tricarbonyl complexes for the hydrogenation of dienes.

  1. Role of intercalation and redox potential in DNA photosensitization by ruthenium(II) polypyridyl complexes: assessment using DNA repair protein tests.

    PubMed

    Gicquel, Etienne; Souchard, Jean-Pierre; Magnusson, Fay; Chemaly, Jad; Calsou, Patrick; Vicendo, Patricia

    2013-08-01

    Here we report that the photoreactivity of ruthenium(II) complexes with nucleobases may not only be modulated by their photoredox properties but also by their DNA binding mode. The damage resulting from photolysis of synthetic oligonucleotides and plasmid DNA by [Ru(bpz)3](2+), [Ru(bipy)3](2+) and the two DNA intercalating agents [Ru(bpz)2dppz](2+) and [Ru(bipy)2dppz](2+) has been monitored by polyacrylamide gel electrophoresis and by tests using proteins involved in DNA repair processes (DNA-PKCs, Ku80, Ku70, and PARP-1). The data show that intercalation controls the nature of the DNA damage photo-induced by ruthenium(II) complexes reacting with DNA via an electron transfer process. The intercalating agent [Ru(bpz)2dppz](2+) is a powerful DNA breaker inducing the formation of both single and double (DSBs) strand breaks which are recognized by the PARP-1 and DNA-PKCs proteins respectively. [Ru(bpz)2dppz](2+) is the first ruthenium(II) complex described in the literature that is able to induce DSBs by an electron transfer process. In contrast, its non-intercalating parent compound, [Ru(bpz)3](2+), is mostly an efficient DNA alkylating agent. Photoadducts are recognized by the proteins Ku70 and Ku80 as with cisplatin adducts. This result suggests that photoaddition of [Ru(bpz)2dppz](2+) is strongly affected by its DNA intercalation whereas its photonuclease activity is exalted. The data clearly show that DNA intercalation decreases drastically the photonuclease activity of ruthenium(II) complexes oxidizing guanine via the production of singlet oxygen. Interestingly, the DNA sequencing data revealed that the ligand dipyridophenazine exhibits on single-stranded oligonucleotides a preference for the 5'-TGCGT-3' sequence. Moreover the use of proteins involved in DNA repair processes to detect DNA damage was a powerful tool to examine the photoreactivity of ruthenium(II) complexes with nucleic acids. PMID:23835850

  2. Electrochemical DNA biosensor for detection of porcine oligonucleotides using ruthenium(II) complex as intercalator label redox

    SciTech Connect

    Halid, Nurul Izni Abdullah; Hasbullah, Siti Aishah; Heng, Lee Yook; Karim, Nurul Huda Abd; Ahmad, Haslina; Harun, Siti Norain

    2014-09-03

    A DNA biosensor detection of oligonucleotides via the interactions of porcine DNA with redox active complex based on the electrochemical transduction is described. A ruthenium(II) complex, [Ru(bpy){sub 2}(PIP)]{sup 2+}, (bpy = 2,2′bipyridine, PIP = 2-phenylimidazo[4,5-f[[1,10-phenanthroline]) as DNA label has been synthesized and characterized by 1H NMR and mass spectra. The study was carried out by covalent bonding immobilization of porcine aminated DNA probes sequences on screen printed electrode (SPE) modified with succinimide-acrylic microspheres and [Ru(bpy){sub 2}(PIP)]{sup 2+} was used as electrochemical redox intercalator label to detect DNA hybridization event. Electrochemical detection was performed by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) over the potential range where the ruthenium (II) complex was active. The results indicate that the interaction of [Ru(bpy){sub 2}(PIP)]{sup 2+} with hybridization complementary DNA has higher response compared to single-stranded and mismatch complementary DNA.

  3. Structure-activity relationships for organometallic osmium arene phenylazopyridine complexes with potent anticancer activity.

    PubMed

    Fu, Ying; Habtemariam, Abraha; Basri, Aida M B H; Braddick, Darren; Clarkson, Guy J; Sadler, Peter J

    2011-10-28

    We report the synthesis and characterisation of 32 half sandwich phenylazopyridine Os(II) arene complexes [Os(η(6)-arene)(phenylazopyridine)X](+) in which X is chloride or iodide, the arene is p-cymene or biphenyl and the pyridine and phenyl rings contain a variety of substituents (F, Cl, Br, I, CF(3), OH or NO(2)). Ten X-ray crystal structures have been determined. Cytotoxicity towards A2780 human ovarian cancer cells ranges from high potency at nanomolar concentrations to inactivity. In general the introduction of an electron-withdrawing group (e.g. F, Cl, Br or I) at specific positions on the pyridine ring significantly increases cytotoxic activity and aqueous solubility. Changing the arene from p-cymene to biphenyl and the monodentate ligand X from chloride to iodide also increases the activity significantly. Activation by hydrolysis and DNA binding appears not to be the major mechanism of action since both the highly active complex [Os(η(6)-bip)(2-F-azpy)I]PF(6) (9) and the moderately active complex [Os(η(6)-bip)(3-Cl-azpy)I]PF(6) (23) are very stable and inert towards aquation. Studies of octanol-water partition coefficients (log P) and subcellular distributions of osmium in A2780 human ovarian cancer cells suggested that cell uptake and targeting to cellular organelles play important roles in determining activity. Although complex 9 induced the production of reactive oxygen species (ROS) in A2780 cells, the ROS level did not appear to play a role in the mechanism of anticancer activity. This class of organometallic osmium complexes has new and unusual features worthy of further exploration for the design of novel anticancer drugs.

  4. Synthesis, characterization, DNA binding studies, photocleavage, cytotoxicity and docking studies of ruthenium(II) light switch complexes.

    PubMed

    Gabra, Nazar Mohammed; Mustafa, Bakheit; Kumar, Yata Praveen; Devi, C Shobha; Srishailam, A; Reddy, P Venkat; Reddy, Kotha Laxma; Satyanarayana, S

    2014-01-01

    A new ligand 3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2yl)phenylboronic acid and its (IPPBA) three ruthenium(II) complexes [Ru(phen)2(IPPBA)](ClO4)2 (1), [Ru(bpy)2(IPPBA)](ClO4)2 (2) and [Ru(dmb)2(IPPBA)](ClO4)2 (3) have been synthesized and characterized by elemental analysis, UV/VIS, IR, (1)H-NMR,(13)C-NMR and mass spectra. The binding behaviors of the three complexes to calf thymus DNA were investigated by absorption spectra, emission spectroscopy, viscosity measurements, thermal denaturation and photoactivated cleavage. The DNA-binding constants for complexes 1, 2 and 3 have been determined to be 7.9 × 10(5) M(-1), 6.7 × 10(5) M(-1) and 2.9 × 10(5) M(-1). The results suggest that these complexes bound to double-stranded DNA in an intercalation mode. Upon irradiation at 365 nm, three ruthenium complexes were found to promote the cleavage of plasmid pBR322 DNA from super coiled form І to nicked form ІІ. Further in the presence of Co(2+), the emission of DNA-Ru(ΙΙ) complexes can be quenched. And when EDTA was added, the emission was recovered. The experimental results show that all three complexes exhibited the "on-off-on" properties of molecular "light switch". The highest Cytotoxicity potential of the complex1 was observed on the Human alveolar adenocarcinoma (A549) cell line. Good agreement was generally found between the spectroscopic techniques and molecular docked model which provides further evidence of groove binding. PMID:23982735

  5. Unmasking the Action of Phosphinous Acid Ligands in Nitrile Hydration Reactions Catalyzed by Arene-Ruthenium(II) Complexes.

    PubMed

    Tomás-Mendivil, Eder; Cadierno, Victorio; Menéndez, María I; López, Ramón

    2015-11-16

    The catalytic hydration of benzonitrile and acetonitrile has been studied by employing different arene-ruthenium(II) complexes with phosphinous (PR2OH) and phosphorous acid (P(OR)2OH) ligands as catalysts. Marked differences in activity were found, depending on the nature of both the P-donor and η(6)-coordinated arene ligand. Faster transformations were always observed with the phosphinous acids. DFT computations unveiled the intriguing mechanism of acetonitrile hydration catalyzed by these arene-ruthenium(II) complexes. The process starts with attack on the nitrile carbon atom of the hydroxyl group of the P-donor ligand instead of on a solvent water molecule, as previously suggested. The experimental results presented herein for acetonitrile and benzonitrile hydration catalyzed by different arene-ruthenium(II) complexes could be rationalized in terms of such a mechanism.

  6. Chiral Ruthenium(II) Polypyridyl Complexes: Stabilization of G-Quadruplex DNA, Inhibition of Telomerase Activity and Cellular Uptake

    PubMed Central

    Yu, Qianqian; Liu, Yanan; Wang, Chuan; Sun, Dongdong; Yang, Xingcheng; Liu, Yanyu; Liu, Jie

    2012-01-01

    Two ruthenium(II) complexes, Λ-[Ru(phen)2(p-HPIP)]2+ and Δ-[Ru(phen)2(p-HPIP)]2+, were synthesized and characterized via proton nuclear magnetic resonance spectroscopy, electrospray ionization-mass spectrometry, and circular dichroism spectroscopy. This study aims to clarify the anticancer effect of metal complexes as novel and potent telomerase inhibitors and cellular nucleus target drug. First, the chiral selectivity of the compounds and their ability to stabilize quadruplex DNA were studied via absorption and emission analyses, circular dichroism spectroscopy, fluorescence-resonance energy transfer melting assay, electrophoretic mobility shift assay, and polymerase chain reaction stop assay. The two chiral compounds selectively induced and stabilized the G-quadruplex of telomeric DNA with or without metal cations. These results provide new insights into the development of chiral anticancer agents for G-quadruplex DNA targeting. Telomerase repeat amplification protocol reveals the higher inhibitory activity of Λ-[Ru(phen)2(p-HPIP)]2+ against telomerase, suggesting that Λ-[Ru(phen)2(p-HPIP)]2+ may be a potential telomerase inhibitor for cancer chemotherapy. MTT assay results show that these chiral complexes have significant antitumor activities in HepG2 cells. More interestingly, cellular uptake and laser-scanning confocal microscopic studies reveal the efficient uptake of Λ-[Ru(phen)2(p-HPIP)]2+ by HepG2 cells. This complex then enters the cytoplasm and tends to accumulate in the nucleus. This nuclear penetration of the ruthenium complexes and their subsequent accumulation are associated with the chirality of the isomers as well as with the subtle environment of the ruthenium complexes. Therefore, the nucleus can be the cellular target of chiral ruthenium complexes for anticancer therapy. PMID:23236402

  7. Noncovalent interactions of metal cations and arenes probed with thallium(I) complexes.

    PubMed

    Jurca, Titel; Korobkov, Ilia; Gorelsky, Serge I; Richeson, Darrin S

    2013-05-20

    The synthesis, characterization, and computational analysis of Tl(I) complexes bearing the bis(imino)pyridine scaffold, [{ArN═CPh}2(NC5H3)]Tl(+)(OTf)(-) (Ar = 2,6-Et2C6H33, 2,5-(t)Bu2C6H3, 4), are reported. The cations of these species showed long Tl-N and Tl-OTf distances indicating only weak or no ligand coordination. Computational analysis of the interactions between the Tl cation and the ligands (orbital populations, bond order, and energy decomposition analysis) point to only minimal covalent interactions of the cation with the ligands. The weak ligand-to-metal donation allows for additional interactions between the Tl cation and arene rings that are either intramolecular, in the case of 3, or intermolecular. From benzene or toluene, 4 crystallizes with inverted sandwich structures having two [{(2,5-(t)Bu2C6H3)N═CPh}2(NC5H3)]Tl(+) cations bridged by either benzene or toluene. A density functional computational description of these Tl-arene contacts required exchange-correlation functionals with long-range exchange corrections (e.g., CAM-B3LYP or LC-PBE) and show that Tl-arene contacts are stabilized by noncovalent interactions.

  8. Encapsulation of Arn complexes by calix[4]arene: endo- vs. exo-complexes

    SciTech Connect

    Ebata, Takayuki; Hontama, Naoya; Haino, Takeharu; Apra, Edoardo; Xantheas, Sotiris

    2010-01-01

    The structure of the calix[4]arene(C4A) Arn complexes has been investigated by laser induced fluorescence spectroscopy, mass-selected resonant two-color two-photon ionization (2C-R2PI) spectroscopy, fragment detected IR photodissociation (FDIRPD) spectroscopy, and high level first principles electronic structure calculations at the MP2 and CCSD(T) levels of theory. C4A has a very high ability to form van der Waals complexes with rare gas atoms. For the C4A Ar dimer two isomers are observed. A major species shows a 45 cm 1 red-shift of its band origin with respect to the monomer, while that of a minor species is 60 cm 1. The binding energy of the major species is determined to be in the range of 350 2250 cm 1 from 2C-R2PI spectroscopy and FDIRPD spectroscopy. Two isomers are also identified in the quantum chemical calculations, depending on whether the Ar atom resides inside (endo) or outside (exo) the C4A. We propose a scheme to derive CCSD(T)/Complete Basis Set (CBS) quality binding energies for the C4A Ar complex based on CCSD(T) calculations with smaller basis sets and the ratio of CCSD(T)/MP2 energies for the smaller model systems benzene Ar and phenol Ar, for which the CCSD(T) level of theory converges to the experimentally determined binding energies. Our best computed estimates for the binding energies of the C4A Ar endo- and endo-complexes at the CCSD(T)/CBS level of theory are 1560 cm 1 and 510 cm 1, respectively. For the C4A Ar2 trimer the calculations support the existence of two nearly isoenergetic isomers: one is the {2:0} endo-complex, in which the Ar2 dimer is encapsulated inside the C4A cavity, and the other is the {1:1} endo exo-complex, in which one Ar resides inside and the other outside the C4A cavity. However, the experimental evidence strongly suggests that the observed species is the {2:0} endo-complex. The endo structural motif is also suggested for the larger C4A Arn complexes because of the observed systematic red-shifts of the complexes

  9. Method for the synthesis of cationic arene complexes of group VII and group VIII metals in strong Broensted acids

    SciTech Connect

    Rubinskaya, M.I.; Kaganovich, V.S.; Kudinov, A.R.

    1988-06-01

    A review of the work on the synthesis of the title complexes has been presented. The interaction of (Ru(eta-C/sub 6/H/sub 6/)Cl/sub 2/)/sub 2/ (I) with AgBF/sub 4/ or AgNO/sub 3/ in an aqueous medium gives (Ru(eta-C/sub 6/H/sub 6/)(H/sub 2/O)/sub 3/)/sup 2 +/, which reacts with arenes in CF/sub 3/COOH to form (Ru(eta-C/sub 6/H/sub 6/)(n-arene))/sup 2 +/ (II). The same complexes have been obtained from complex I by reacting it with arenes in heptane in the presence of AlCl/sub 3/. It has been found that cations II form when complex I is boiled directly with arenes in CF/sub 3/COOH, and in the cases of C/sub 6/H/sub 6/, C/sub 6/Me/sub 6/, and naphthalene, they form at room temperature in H/sub 2/SO/sub 4/. The complexes (Os(eta-Me/sub 3/C/sub 6/H/sub 3/)(n-arene))/sup 2 +/ have been obtained by boiling (Os(eta-Me/sub 3/C/sub 6/H/sub 3/)Cl/sub 2/)/sub 2/ with the arene in CF/sub 3/COOH. The complexes (M(eta-C/sub 4/Me/sub 5/)-(eta-arene))/sup 2 +/ (M = Rh, Ir) have been obtained in a similar manner from (M(eta-C/sub 5/Me/sub 5/)Cl/sub 2/)/sub 2/. Hypotheses regarding the structure of the intermediates formed during the reactions investigated have been advanced.

  10. Noncovalent Complexation of Monoamine Neurotransmitters and Related Ammonium Ions by Tetramethoxy Tetraglucosylcalix[4]arene

    NASA Astrophysics Data System (ADS)

    Torvinen, Mika; Kalenius, Elina; Sansone, Francesco; Casnati, Alessandro; Jänis, Janne

    2012-02-01

    The noncovalent complexation of monoamine neurotransmitters and related ammonium and quaternary ammonium ions by a conformationally flexible tetramethoxy glucosylcalix[4]arene was studied by electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. The glucosylcalixarene exhibited highest binding affinity towards serotonin, norepinephrine, epinephrine, and dopamine. Structural properties of the guests, such as the number, location, and type of hydrogen bonding groups, length of the alkyl spacer between the ammonium head-group and the aromatic ring structure, and the degree of nitrogen substitution affected the complexation. Competition experiments and guest-exchange reactions indicated that the hydroxyl groups of guests participate in intermolecular hydrogen bonding with the glucocalixarene.

  11. A comparative DFT study on aquation and nucleobase binding of ruthenium (II) and osmium (II) arene complexes.

    PubMed

    Wang, Hanlu; Zeng, Xingye; Zhou, Rujin; Zhao, Cunyuan

    2013-11-01

    The potential energy surfaces of the reactions of organometallic arene complexes of the type [(η (6)-arene)M(II)(pic)Cl] (where pic = 2-picolinic acid, M = Ru or Os) were examined by a DFT computational study. Among the seven density functional methods, hybrid exchange functional B3LYP outperforms the others to explain the aquation of the complexes. The reactions and binding energies of Ru(II) and Os(II) arene complexes with both 9EtG and 9EtA were studied to gain insight into the reactivity of these types of organometallic complexes with DNA. The obtained data rationalize experimental observation, contributing to partly understanding the potential biological and medical applications of organometallic complexes.

  12. A comparative DFT study on aquation and nucleobase binding of ruthenium (II) and osmium (II) arene complexes.

    PubMed

    Wang, Hanlu; Zeng, Xingye; Zhou, Rujin; Zhao, Cunyuan

    2013-11-01

    The potential energy surfaces of the reactions of organometallic arene complexes of the type [(η (6)-arene)M(II)(pic)Cl] (where pic = 2-picolinic acid, M = Ru or Os) were examined by a DFT computational study. Among the seven density functional methods, hybrid exchange functional B3LYP outperforms the others to explain the aquation of the complexes. The reactions and binding energies of Ru(II) and Os(II) arene complexes with both 9EtG and 9EtA were studied to gain insight into the reactivity of these types of organometallic complexes with DNA. The obtained data rationalize experimental observation, contributing to partly understanding the potential biological and medical applications of organometallic complexes. PMID:24037457

  13. Determination of association constant of host-guest supramolecular complex (molecular recognition of carbamazepine, antiseizure drug, with calix(4)arene).

    PubMed

    Meenakshi, C; Jayabal, P; Ramakrishnan, V

    2015-12-01

    The thermodynamic property of the host-guest, inclusion complex formed between p-t-butyl calix(4)arene which is a supramolecule, and the antiseizure drug, carbamazepine was studied. p-t-Butyl calix(4)arene has been used as a host molecule and carbamazepine as a guest molecule. Optical absorption spectral studies were carried out to investigate the molecular recognition properties of p-t-butyl calix(4)arene with carbamazepine. The stochiometry of the host-guest complexes formed and the association constant were determined. An interesting 1:2 stochiometric host-guest complex was formed. Job's continuous method of variation and Benesi-Hildebrand expression were used for the determination of binding constant and the stochiometry of the host-guest complex formed. Molecular dimension of the host molecule plays a vital role in the formation of the host-guest stochiometric complexes.

  14. Förster resonance energy transfer studies of luminescent gold nanoparticles functionalized with ruthenium(II) and rhenium(I) complexes: modulation via esterase hydrolysis.

    PubMed

    Leung, Frankie Chi-Ming; Tam, Anthony Yiu-Yan; Au, Vonika Ka-Man; Li, Mei-Jin; Yam, Vivian Wing-Wah

    2014-05-14

    A number of ruthenium(II) and rhenium(I) bipyridine complexes functionalized with lipoic acid moieties have been synthesized and characterized. Functionalization of gold nanoparticles with these chromophoric ruthenium(II) and rhenium(I) complexes has resulted in interesting supramolecular assemblies with Förster resonance energy transfer (FRET) properties that could be modulated via esterase hydrolysis. The luminescence of the metal complex chromophores was turned on upon cleavage of the ester bond linkage by esterase to reduce the efficiency of FRET quenching. The prepared nanoassembly conjugates have been characterized by transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), UV-visible spectroscopy, and emission spectroscopy. The quenching mechanism has also been studied by transient absorption and time-resolved emission decay measurements. The FRET efficiencies were found to vary with the nature of the chromophores and the length of the spacer between the donor (transition metal complexes) and the acceptor (gold nanoparticles).

  15. Kinetic effects of sulfur oxidation on catalytic nitrile hydration: nitrile hydratase insights from bioinspired ruthenium(II) complexes.

    PubMed

    Kumar, Davinder; Nguyen, Tho N; Grapperhaus, Craig A

    2014-12-01

    Kinetic investigations inspired by the metalloenzyme nitrile hydratase were performed on a series of ruthenium(II) complexes to determine the effect of sulfur oxidation on catalytic nitrile hydration. The rate of benzonitrile hydration was quantified as a function of catalyst, nitrile, and water concentrations. Precatalysts L(n)RuPPh3 (n = 1-3; L(1) = 4,7-bis(2'-methyl-2'-mercapto-propyl)-1-thia-4,7-diazacyclononane; L(2) = 4-(2'-methyl-2'-sulfinatopropyl)-7-(2'-methyl-2'-mercapto-propyl)-1-thia-4,7-diazacyclononane; L(3) = 4-(2'-methyl-2'-sulfinatopropyl)-7-(2'-methyl-2'-sulfenato-propyl)-1-thia-4,7-diazacyclononane) were activated by substitution of triphenylphosphine with substrate in hot dimethylformamide solution. Rate measurements are consistent with a dynamic equilibrium between inactive aqua (L(n)Ru-OH2) and active nitrile (L(n)Ru-NCR) derivatives with K = 21 ± 1, 9 ± 0.9, and 23 ± 3 for L(1) to L(3), respectively. Subsequent hydration of the L(n)Ru-NCR intermediate yields the amide product with measured hydration rate constants (k's) of 0.37 ± 0.01, 0.82 ± 0.07, and 1.59 ± 0.12 M(-1) h(-1) for L(1) to L(3), respectively. Temperature dependent studies reveal that sulfur oxidation lowers the enthalpic barrier by 27 kJ/mol, but increases the entropic barrier by 65 J/(mol K). Density functional theory (DFT) calculations (B3LYP/LanL2DZ (Ru); 6-31G(d) (all other atoms)) support a nitrile bound catalytic cycle with lowering of the reaction barrier as a consequence of sulfur oxidation through enhanced nitrile binding and attack of the water nucleophile through a highly organized transition state. PMID:25397591

  16. Detection and differentiation of neutral organic compounds by 19F NMR with a tungsten calix[4]arene imido complex.

    PubMed

    Zhao, Yanchuan; Swager, Timothy M

    2013-12-18

    Fluorinated tungsten calix[4]arene imido complexes were synthesized and used as receptors to detect and differentiate neutral organic compounds. It was found that the binding of specific neutral organic molecules to the tungsten centers induces an upfield shift of the fluorine atom appended on the arylimido group, the extent of which is highly dependent on electronic and steric properties. We demonstrate that the specific bonding and size-selectivity of calix[4]arene tungsten-imido complex combined with (19)F NMR spectroscopy is a powerful new method for the analysis of complex mixtures.

  17. Scandium arene inverted-sandwich complexes supported by a ferrocene diamide ligand.

    PubMed

    Huang, Wenliang; Khan, Saeed I; Diaconescu, Paula L

    2011-07-13

    The synthesis and characterization of the first scandium arene inverted-sandwich complexes supported by a ferrocene diamide ligand (NN(fc)) are reported. Through the use of (NN(fc))ScI(THF)(2) as a precursor and potassium graphite (KC(8)) as a reducing agent, the naphthalene and anthracene complexes [(NN(fc))Sc](2)(μ-C(10)H(8)) and [(NN(fc))Sc](2)(μ-C(14)H(10)), respectively, were synthesized and isolated in moderate to high yields. Both molecular structures feature an inverted-sandwich geometry and exhibit short Fe-Sc distances. DFT calculations were employed to gain understanding of the electronic structures of these new scandium arene complexes. A variable-temperature NMR spectroscopic study of [(NN(fc))Sc](2)(μ-C(14)H(10)) indicated that two different structures are accessible in solution. Reactivity studies showed that the naphthalene complex [(NN(fc))Sc](2)(μ-C(10)H(8)) can be converted to the corresponding anthracene species [(NN(fc))Sc](2)(μ-C(14)H(10)) and that [(NN(fc))Sc](2)(μ-C(10)H(8)) can act as either a reductant or a proton acceptor. The reaction of [(NN(fc))Sc](2)(μ-C(10)H(8)) with excess pyridine led to a rare example of C-C bond formation between two pyridine rings at the para position.

  18. Sweetening ruthenium and osmium: organometallic arene complexes containing aspartame.

    PubMed

    Gray, Jennifer C; Habtemariam, Abraha; Winnig, Marcel; Meyerhof, Wolfgang; Sadler, Peter J

    2008-09-01

    The novel organometallic sandwich complexes [(eta(6)-p-cymene)Ru(eta(6)-aspartame)](OTf)(2) (1) (OTf = trifluoromethanesulfonate) and [(eta(6)-p-cymene)Os(eta(6)-aspartame)](OTf)(2) (2) incorporating the artificial sweetener aspartame have been synthesised and characterised. A number of properties of aspartame were found to be altered on binding to either metal. The pK(a) values of both the carboxyl and the amino groups of aspartame are lowered by between 0.35 and 0.57 pH units, causing partial deprotonation of the amino group at pH 7.4 (physiological pH). The rate of degradation of aspartame to 3,6-dioxo-5-phenylmethylpiperazine acetic acid (diketopiperazine) increased over threefold from 0.12 to 0.36 h(-1) for 1, and to 0.43 h(-1) for 2. Furthermore, the reduction potential of the ligand shifted from -1.133 to -0.619 V for 2. For the ruthenium complex 1 the process occurred in two steps, the first (at -0.38 V) within a biologically accessible range. This facilitates reactions with biological reductants such as ascorbate. Binding to and activation of the sweet taste receptor was not observed for these metal complexes up to concentrations of 1 mM. The factors which affect the ability of metal-bound aspartame to interact with the receptor site are discussed.

  19. Catalytic dehydrogenation of cycloalkanes to arenes by a dihydrido iridium P-C-P pincer complex

    SciTech Connect

    Gupta, M.; Hagen, C.; Cramer, R.E.; Jensen, C.M.; Kaska, W.C.

    1997-01-29

    We recently found that the iridium P-C-P pincer complex IrH{sub 2}[C{sub 6}H{sub 3}-2,6-(CH{sub 2}-PBu{sup T}{sub 2}){sub 2}] (1) is a highly active, homogeneous catalyst for the transfer dehydrogenation of cyclooctane with unusual long-term stability at temperatures as high as 200 {degree}C. This reactivity has now been extended to the catalytic transfer dehydrogenation of cycloalkanes to arenes. We report this novel catalytic activity as well as the results of an X-ray structure determination of 1. 15 refs., 1 fig., 1 tab.

  20. Iron(II) and ruthenium(II) complexes containing P, N, and H ligands: structure, spectroscopy, electrochemistry, and reactivity.

    PubMed

    Chen, Jinzhu; Szalda, David J; Fujita, Etsuko; Creutz, Carol

    2010-10-18

    The purpose of this work was to explore the possibility of using iron(II) hydrides in CO(2) reduction and to compare their reactivity to that of their ruthenium analogues. Fe(bpy)(P(OEt)(3))(3)H(+) and Ru(bpy)(P(OEt)(3))(3)H(+) do not react with CO(2) in acetonitrile, but the one-electron-reduction products of Ru(bpy)(P(OEt)(3))(3)H(+) and Ru(bpy)(2)(P(OEt)(3))H(+) and the two-electron-reduction product of Fe(bpy)(P(OEt)(3))(3)H(+) do. Ru(bpy)(2)(P(OEt)(3))H(+) also reacts slowly with CO(2) to give a formate complex [as reported previously by Albertin et al. (Inorg. Chem. 2004, 43, 1336)] with a second-order rate constant of ∼4 × 10(-3) M(-1) s(-1) in methanol. The structures for the hydride complexes [Fe(bpy)(P(OEt)(3))(3)H](+) and [Ru(bpy)(2)(P(OEt)(3))H](+) and for the (η(5)-Cp)bis- and -tris-PTA complexes (PTA = 1,3,5-triaza-7-phosphatricyclo[3.3.1.13.7]decane) of iron(II) are reported. These and the CpFe(CO)(bpy)(+) and Fe(II)PNNP compounds have been subjected to electrochemical and UV-vis spectroscopic characterization. Fe(bpy)(P(OEt)(3))(3)H(+) exhibits a quasi-reversible oxidation at +0.42 V vs AgCl/Ag in acetonitrile; Ru(bpy)(P(OEt)(3))(3)H(+) and Ru(bpy)(2)(P(OEt)(3))H(+) are oxidized irreversibly at +0.90 and +0.55 V, respectively, vs AgCl/Ag. The reduction site for Fe(bpy)(P(OEt)(3))(3)H(+) and Fe(bpy)(P(OEt)(3))(3)(CH(3)CN)(2+) appears to be the metal and gives rise to a two-electron process. The bpy-centered reductions are negatively shifted in the ruthenium(II) hydride complexes, compared to the acetonitrile complexes. The results of attempts to prepare other iron(II) hydrides are summarized. PMID:20857940

  1. Chromium films obtained by pyrolysis of bis(arene)chromium complexes in presence of sulfur-containing additives

    SciTech Connect

    Lugin, A.S.; Polikarpov, V.B.; Dodonov, V.A.; Klement'ev, E.K.

    1988-11-20

    Sulfur and its compounds catalyze deposition of chromium during thermal decomposition of its bis(arene) complexes. In this investigation we studied the influence of diphenyl and dibenzyl sulfides on this process. The character of the dependence of the rate of chromium deposition on the dibenzyl sulfide concentration in the original mixture shows that sulfur compounds, like chlorinated additives, have a promoting effect on the autocatalytic process of pyrolysis of bis(arene) chromium complexes. Aromatic sulfides raise the rate of chromium deposition, suppress secondary processes of ligands dehydrogenation, and accordingly lower the carbon contents in the deposits during thermal decomposition of bis(arene)chromium complexes. Sulfur compounds direct the deposition process toward formation of ordered crystalline phases of chromium and its carbides.

  2. Encapsulation of Arn complexes by Calix[4]arene: Endo- vs. exo-complexes

    SciTech Connect

    Ebata, Takayuki; Hontama, Naoya; Inokuchi, Yoshiya; Haino, Takeharu; Apra, Edoardo; Xantheas, Sotiris S.

    2010-05-14

    The structure of the calix[4]arene(C4A)-Arn complexes has been investigated by laser induced fluorescence spectroscopy, mass-selected resonant two-color two-photon ionization (2C-R2PI) spectroscopy, fragment detected IR photodissociation (FDIRPD) spectroscopy, and high level first principles electronic structure calculations at the MP2 and CCSD(T) levels of theory. C4A has a very high ability of forming van der Waals complexes with rare gas atoms. For the C4A-Ar dimer two isomers are observed. A major species shows a 45 cm-1 red-shift of its band origin with respect to the monomer, while that of a minor species is 60 cm-1. The binding energy of the major species is determined to be in the range of 350 - 2250 cm-1 from 2C-R2PI spectroscopy and FDIRPD spectroscopy. Two isomers are also identified in the quantum chemical calculations, depending on whether the Ar atom resides inside (endo) or outside (exo) the C4A. We propose a scheme to derive CCSD(T)-quality binding energies for the C4A-Ar complex based on the ratio of CCSD(T)/MP2 energies for the smaller model systems Benzene-Ar and Phenol-Ar, for which the CCSD(T) level of theory converges to the experimentally determined binding energies. Our best computed estimates for the binding energies of the C4A-Ar endo- and endo-complexes at the CCSD(T)/Complete Basis Set (CBS) level of theory are 1560 cm-1 and 510 cm-1, respectively. For the C4A-Ar2 trimer the calculations support the existence of two nearly isoenergetic isomers: one is the {2:0} endo-complex, in which the Ar2 dimer is encapsulated inside the C4A cavity, and the other is the {1:1} endo-exo-complex, in which one Ar resides inside and the other outside the C4A cavity. However, the experimental evidence 3 strongly suggests that the observed species is the {2:0} endo-complex. The endo structural motif is also suggested for the larger C4A-Arn complexes because of the systematic red-shifts of the complexes with the number of bound Ar atoms suggesting that the

  3. Titanium "constrained geometry" complexes with pendant arene groups.

    PubMed

    Dureen, Meghan A; Brown, Christopher C; Morton, Jason G M; Stephan, Douglas W

    2011-03-28

    The synthesis of the proligands C(5)Me(4)HSiMe(2)N(H)R) (R = CMe(2)Ph 1, 2-C(6)H(4)Ph 2) was accomplished via a straightforward salt metathesis reaction of the appropriate lithium amide and ClSiMe(2)(C(5)Me(5)H). Generation of the dilithio salt and reaction with TiCl(3)·(THF)(3) followed by oxidation gave C(5)Me(4)SiMe(2)N(C(6)H(4)Ph)TiCl(2) (3) in low yield. In contrast, deprotonation of 1 and 2 and reaction with (Me(2)N)(2)TiCl(2) afforded C(5)Me(4)(SiMe(2)NR)Ti(NMe(2))(2) (R = CMe(2)Ph 4, 2-C(6)H(4)Ph 5), respectively, in good yields Treatment with MeI gave the analogs C(5)Me(4)(SiMe(2)NR)TiI(2) (R = CMe(2)Ph 6, 2-C(6)H(4)Ph 7). Reduction of 7 with potassium graphite afforded C(5)Me(4)(SiMe(2)NC(6)H(4)Ph)Ti 8. Treatment of 6 and 7 with MeMgBr afforded C(5)Me(4)(SiMe(2)NR)TiMe(2) (R = CMe(2)Ph 9, 2-C(6)H(4)Ph 10). Complexes 9 and 10 in combination with the activator [Ph(3)C][B(C(6)F(5))(4)] catalyzed the polymerization of styrene and ethylene. Copolymerization was also investigated. While the catalyst derived from 10 showed poor activity, compound 9 showed markedly higher activity than 10 and (C(5)Me(4))SiMe(2)(NtBu)]TiMe(2). PMID:21298170

  4. New RuII (arene) complexes with halogen-substituted bis- and tris(pyrazol-1-yl)borate ligands.

    PubMed

    Orbisaglia, Serena; Di Nicola, Corrado; Marchetti, Fabio; Pettinari, Claudio; Pettinari, Riccardo; Martins, Luísa M D R S; Alegria, Elisabete C B A; da Silva, M Fátima C Guedes; Rocha, Bruno G M; Kuznetsov, Maxim L; Pombeiro, Armando J L; Skelton, Brian W; Sobolev, Alexandre N; White, Allan H

    2014-03-24

    [RuCl(arene)(μ-Cl)]2 dimers were treated in a 1:2 molar ratio with sodium or thallium salts of bis- and tris(pyrazolyl)borate ligands [Na(Bp(Br3))], [Tl(Tp(Br3))], and [Tl(Tp(iPr, 4Br))]. Mononuclear neutral complexes [RuCl(arene)(κ(2)-Bp(Br3))] (1: arene=p-cymene (cym); 2: arene=hexamethylbenzene (hmb); 3: arene=benzene (bz)), [RuCl(arene)(κ(2)-Tp(Br3))] (4: arene=cym; 6: arene=bz), and [RuCl(arene)(κ(2)-Tp(iPr, 4Br))] (7: arene=cym, 8: arene=hmb, 9: arene=bz) have been always obtained with the exception of the ionic [Ru2 (hmb)2-(μ-Cl)3][Tp(Br3)] (5'), which formed independently of the ratio of reactants and reaction conditions employed. The ionic [Ru-(CH3OH)(cym)(κ(2)-Bp(Br3))][X] (10: X=PF6, 12: X=O3SCF3) and the neutral [Ru(O2CCF3)(cym)(κ(2)-Bp(Br3))] (11) have been obtained by a metathesis reaction with corresponding silver salts. All complexes 1-12 have been characterized by analytical and spectroscopic data (IR, ESI-MS, (1)H and (13)C NMR spectroscopy). The structures of the thallium and calcium derivatives of ligand Tp(Br3), [Tl(Tp(Br3))] and [Ca(dmso)6][Tp(Br3)]2 ⋅2 DMSO, of the complexes 1, 4, 5', 6, 11, and of the decomposition product [RuCl(cym)(Hpz(iPr, 4Br))2][Cl] (7') have been confirmed by using single-crystal X-ray diffraction. Electrochemical studies showed that 1-9 and 11 undergo a single-electron Ru(II) →Ru(III) oxidation at a potential, measured by cyclic voltammetry, which allows comparison of the electron-donor characters of the bis- and tris(pyrazol-1-yl)borate and arene ligands, and to estimate, for the first time, the values of the Lever EL ligand parameter for Bp(Br3), Tp(Br3), and Tp(iPr, 4Br). Theoretical calculations at the DFT level indicated that both oxidation and reduction of the Ru complexes under study are mostly metal-centered with some involvement of the chloride ligand in the former case, and also demonstrated that the experimental isolation of the μ(3)-binuclear complex 5' (instead of the mononuclear 5

  5. Direct observation of. eta. sup 2 -arene complexes of ((C sub 5 Me sub 5 )Rh(PMe sub 3 ))

    SciTech Connect

    Jones, W.D.; Dong, L. )

    1989-01-01

    Over the past few years, there has been substantial progress in studies of the mechanism of activation of aliphatic aromatic C-H bonds by transition metals. In particular, earlier studies in the authors group have indicated that arenes coordinate to ((Ce{sub 5}Me{sub 5})Rh(PMe{sub 3})) in an {eta}{sup 2} fashion prior to C-H bond oxidative addition, and that this initial coordination permits the activation of aromatic C-H bonds to compete with aliphatic C-H bond activation. The evidence for {eta}{sup 2}-arene coordination relies heavily on indirect experiments (intramolecular isomerization of an aryl deuteride, kinetic isotope effect experiments), as the only direct evidence for arene coordination was with p-di-tert-butylbenzene at low temperature. They report here the room temperature observation of {eta}{sup 2}-arene complexes of ((C{sub 5}Me{sub 5})Rh(PMe{sub 3})) and an equilibrium between and {eta}{sup 2}-arene complex and its aryl hydride counterpart.

  6. Complexation of solvents and conformational equilibria in solutions of the simplest calix[4]arenes

    NASA Astrophysics Data System (ADS)

    Surov, Oleg V.; Krestianinov, Mikhail A.; Voronova, Marina I.

    2015-01-01

    Structure optimization and calculation of electronic adsorption spectra of 25,26,27,28-tetrahydroxycalix[4]arene and 25,27-dimethoxy-26,28-dihydroxycalix[4]arene conformers have been performed by density-functional theory using hybrid B3LYP functional in cc-p VTZ and cc-p VDZ basis sets in Gaussian 09 package. Analysis of experimental UV-Vis spectra of solutions of 25,26,27,28-tetrahydroxycalix[4]arene, 4-tert-butylcalix[4]arene and 25,27-dimethoxy-26,28-dihydroxycalix[4]arene in various solvents has been carried out. It was shown that the ratio of absorption maxima at characteristic wavelengths at ca. 274 and 283 nm may be used to assess the extent of calix[4]arene/solvent interactions. The conclusion is drawn that spectral characteristics of calix[4]arenes are strongly affected by acid-base interactions.

  7. Metal arene complexes in coal structure determination: Quarterly report for the period June 1987-August 1987

    SciTech Connect

    Woolsey, N.F.

    1987-11-01

    The formation of benzylic hydroperoxides was shown to be a viable synthetic objective by their cleavage to oxygenated species in moderate, unoptimized yields. Oxidation of benzylic anions of metal arene complexes to oxygenated derivatives such as an alcohol, ketone or hydroperoxide are satisfactory target derivatives for this study. Oxidation of the benzylic anion of hexamethylbenzenechromiumtricarbonyl using a phenyl tosyloxaziridine and with chromium pentoxide gave low yields of the desired products. Electrochemical oxidation of a related iron complex anion in the presence of oxygen resulted in metal rather than anion oxidation. The cycloaddition reactions previously reported were extended but a reaction with an isocyanate gave several unidentified products. Attempted rhodium insertion in a phenyl-benzylic carbon-carbon bond resulted in aryl carbon-hydrogen insertion and ultimately formation of a Rh/sub 2//sup +4/ dimeric complex.

  8. Synthesis of axially chiral benzamides utilizing tricarbonyl(arene)chromium complexes.

    PubMed

    Koide, H; Uemura, M

    2000-06-01

    Axially chiral N,N-diethyl 2,6-disubstituted benzamides were stereo-selectively prepared utilizing planar chiral (arene)chromium complexes as an enantiomerically active form by following two methods. Ortho-lithiation of the enantiomerically pure planar chiral tricarbonyl(N,N-diethyl 2-methylbenzamide)chromium complex followed by electrophilic quenching gave axially chiral 2-methyl-6-substituted N,N-diethyl benzamide chromium complexes. Photo-oxidative demetalation produced the chromium-free axially chiral benzamides as optically active compounds. An alternative method for the preparation of axial chiral benzamides is an enantioselective lithiation at the benzylic methyl of meso tricarbonyl(N,N-diethyl 2,6-dimethylbenzamide)chromium with appropriate chiral lithium amide base followed by quenching with alkyl halides. PMID:10824151

  9. A dendritic nano-sized hexanuclear ruthenium(II) complex as a one- and two-photon luminescent tracking non-viral gene vector

    PubMed Central

    Qiu, Kangqiang; Yu, Bole; Huang, Huaiyi; Zhang, Pingyu; Huang, Juanjuan; Zou, Shanshan; Chen, Yu; Ji, Liangnian; Chao, Hui

    2015-01-01

    Fluorescent tracking gene delivery could provide us with a better understanding of the critical steps in the transfection process. However, for in vivo tracking applications, a small diameter (<10 nm) is one of the rigorous requirements for tracking vectors. Herein, we have demonstrated a new paradigm for two-photon tracking gene delivery based on a dendritic nano-sized hexanuclear ruthenium(II) polypyridyl complex. Because this metallodendrimer has a multivalent periphery, the complex, which is 6.1 nm, showed high stability and excellent dispersibility and could stepwise condense DNA in vitro. With the outstanding photochemical properties of Ru(II) polypyridyl, this complex could track gene delivery in vivo using one- and two-photon imaging. PMID:26185052

  10. Catalytic water oxidation by ruthenium(II) quaterpyridine (qpy) complexes: evidence for ruthenium(III) qpy-N,N'''-dioxide as the real catalysts.

    PubMed

    Liu, Yingying; Ng, Siu-Mui; Yiu, Shek-Man; Lam, William W Y; Wei, Xi-Guang; Lau, Kai-Chung; Lau, Tai-Chu

    2014-12-22

    Polypyridyl and related ligands have been widely used for the development of water oxidation catalysts. Supposedly these ligands are oxidation-resistant and can stabilize high-oxidation-state intermediates. In this work a series of ruthenium(II) complexes [Ru(qpy)(L)2 ](2+) (qpy=2,2':6',2'':6'',2'''-quaterpyridine; L=substituted pyridine) have been synthesized and found to catalyze Ce(IV) -driven water oxidation, with turnover numbers of up to 2100. However, these ruthenium complexes are found to function only as precatalysts; first, they have to be oxidized to the qpy-N,N'''-dioxide (ONNO) complexes [Ru(ONNO)(L)2 ](3+) which are the real catalysts for water oxidation.

  11. Lifetimes, spectra, and quenching of the excited states of polypyridine complexes of iron(II), ruthenium(II), and osmium(II)

    SciTech Connect

    Creutz, C.; Chou, M.; Netzel, T.L.; Okumura, M.; Sutin, N.

    1980-02-13

    The lifetimes of the excited states formed by 530-nm excitation of polypyridine complexes of iron(II) (FeL/sub 3//sup 2 +/) and osmium(II) (OsL/sub 3//sup 2 +/) have been determined by laser flash-photolysis techniques. The FeL/sub 3//sup 2 +/ lifetimes, measured in water at room temperature using picosecond absorption spectrometry, are as follows (L,tau +- sigma(ns)):2,2',2''-terpyridine (2.54 +- 0.13); 2,2'-bipyridine (0.81 +- 0.07); 4,4'-dimethyl(2,2'-bipyridine) (0.76 +- 0.04); 1,10-phenanthroline (0.80 +- 0.07); 4,7-(diphenyl sulfonate)-1,10-phenanthroline (0.43 +- 0.03). Lifetimes for the analogous complexes of osmium(II) lie in the range 10-100 ns under the same conditions. Unlike the excited states of Ru(bpy)/sub 3//sup 2 +/ and Os(bpy)/sub 3//sup 2 +/ (lambda/sub max/430-460 nm, epsilon approx. 5 x 10/sup 3/ M/sup -1/ cm-/sup 1/), the excited state of Fe(bpy)/sub 3//sup 2 +/ does not luminesce or absorb significantly in the visible (epsilon < 10/sup 3/ M/sup -1/ cm/sup -1/ at lambda greater than or equal to 350 nm) but does exhibit intense absorption below approx. 325 nm. Rate constants for the quenching of the excited states of polypyridine complexes of osmium(II) and ruthenium(II) by ground-state polypyridine complexes of iron(II), ruthenium(II), and osmium(II) are reported and are ascribed to either electron-transfer or energy-transfer processes. The excited states of tris(2,2'-bipyridine)iron(II) and of bis(2,2',2''-terpyridine)iron(II) undergo reaction with Fe/sub aq//sup 3 +/ (0.5 M H/sub 2/SO/sub 4/, 25/sup 0/C) with a rate constant less than or equal to 1 x 10/sup 7/ M-/sup 1/ s/sup -1/. Based on a comparison of its properties with those of the luminescent charge-transfer excited states of ruthenium(II) and osmium(II) polypyridine complexes the excited state of FeL/sub 3//sup 2 +/ is identified as a ligand-field state.

  12. Ruthenium(II) polypyridyl complexes with hydrophobic ancillary ligand as Aβ aggregation inhibitors.

    PubMed

    Vyas, Nilima A; Ramteke, Shefali N; Kumbhar, Avinash S; Kulkarni, Prasad P; Jani, Vinod; Sonawane, Uddhavesh B; Joshi, Rajendra R; Joshi, Bimba; Erxleben, Andrea

    2016-10-01

    The synthesis, spectral and electrochemical characterization of the complexes of the type [Ru(NN)2(txbg)](2+) where NN is 2,2'-bipyridine (bpy) (1), 1,10-phenanthroline (phen) (2), dipyrido [3,2-d:2',3f] quinoxaline (dpq) (3), and dipyrido[3,2-a:2',3'-c]phenazine (dppz) (4) which incorporate the tetra-xylene bipyridine glycoluril (txbg) as the ancillary ligand are described in detail. Crystal structures of ligand txbg and complex 2 were solved by single crystal X-ray diffraction. Thioflavin T (ThT) fluorescence and Transmission Electron Microscopy (TEM) results indicated that at micromolar concentration all complexes exhibit significant potential of Aβ aggregation inhibition, while the ligand txbg displayed weak activity towards Aβ aggregation. Complex 1 showed relatively low inhibition (70%) while complexes 2-4 inhibited nearly 100% Aβ aggregation after 240 h of incubation. The similar potential of complexes 2-4 and absence of any trend in their activity with the planarity of polypyridyl ligands suggests there is no marked effect of planarity of coligands on their inhibitory potential. Further studies on acetylcholinesterase (AChE) inhibition indicated very weak activity of these complexes against AChE. Detailed interactions of Aβ with both ligand and complex 2 have been studied by molecular modeling. Complex 2 showed interactions involving all three polypyridyl ligands with hydrophobic region of Aβ. Furthermore, the toxicity of these complexes towards human neuroblastoma cells was evaluated by MTT assay and except complex 4, the complexes displayed very low toxicity. PMID:27406812

  13. Conjugation of a Ru(II) arene complex to neomycin or to guanidinoneomycin leads to compounds with differential cytotoxicities and accumulation between cancer and normal cells.

    PubMed

    Grau-Campistany, Ariadna; Massaguer, Anna; Carrion-Salip, Dolors; Barragán, Flavia; Artigas, Gerard; López-Senín, Paula; Moreno, Virtudes; Marchán, Vicente

    2013-05-01

    with the guanidinylated conjugate, since its cytotoxicity in the normal cell line (IC50 = 12.75 μM for 3) was similar or even lower than that found in MCF-7 and DU-145 cancer cell lines, respectively. Cell uptake studies performed by ICP-MS with conjugates 2 and 3 revealed that guanidinylation of the neomycin moiety had a positive effect on accumulation (about 3-fold higher in DU-145 and 4-fold higher in HEK293), which correlates well with the higher antiproliferative activity of 3. Interestingly, despite the slightly higher accumulation in the normal cell than in the cancer cell line (about 1.4-fold), guanidinoneomycin-ruthenium conjugate (3) was more cytotoxic to cancer cells (about 1.8-fold), whereas the opposite tendency applied for neomycin-ruthenium conjugate (2). Such differences in cytotoxic activity and cellular accumulation between cancer and normal cells open the way to the creation of more selective, less toxic anticancer metallodrugs by conjugating cytotoxic metal-based complexes such as ruthenium(II) arene derivatives to guanidinoglycosides.

  14. Ruthenium(II) and iridium(III) complexes featuring NHC-sulfonate chelate.

    PubMed

    Rajaraman, A; Sahoo, A R; Hild, F; Fischmeister, C; Achard, M; Bruneau, C

    2015-10-28

    Three new complexes bearing a chelating (κ(2)C,O) NHC-SO3 ligand have been prepared. An original method for the synthesis of the imidazolium-sulfonate NHC precursor is described. The 5-membered ruthena- and irida-cycle containing complexes were fully characterized and evaluated in a series of catalytic transformations involving hydrogen auto-transfer processes.

  15. Visible-Light-Driven Photoisomerization and Increased Rotation Speed of a Molecular Motor Acting as a Ligand in a Ruthenium(II) Complex.

    PubMed

    Wezenberg, Sander J; Chen, Kuang-Yen; Feringa, Ben L

    2015-09-21

    Toward the development of visible-light-driven molecular rotary motors, an overcrowded alkene-based ligand and the corresponding ruthenium(II) complex is presented. In our design, a 4,5-diazafluorenyl coordination motif is directly integrated into the motor function. The photochemical and thermal isomerization behavior has been studied by UV/Vis and NMR spectroscopy. Upon coordination to a Ru(II) bipyridine complex, the photoisomerization process can be driven by visible (λmax = 450 nm) instead of UV light and furthermore, a large increase of the speed of rotation is noted. DFT calculations point to a contraction of the diazafluorenyl lower half upon metal-coordination resulting in reduced steric hindrance in the "fjord region" of the molecule. Consequently, it is shown that metal-ligand interactions can play an important role in the adjustment of both photophysical and thermodynamic properties of molecular motors.

  16. RNA and DNA binding of inert oligonuclear ruthenium(II) complexes in live eukaryotic cells.

    PubMed

    Li, Xin; Gorle, Anil K; Ainsworth, Tracy D; Heimann, Kirsten; Woodward, Clifford E; Collins, J Grant; Keene, F Richard

    2015-02-28

    Confocal microscopy was used to study the intracellular localisation of a series of inert polypyridylruthenium(II) complexes with three eukaryotic cells lines - baby hamster kidney (BHK), human embryonic kidney (HEK-293) and liver carcinoma (Hep-G2). Co-staining experiments with the DNA-selective dye DAPI demonstrated that the di-, tri- and tetra-nuclear polypyridylruthenium(II) complexes that are linked by the bis[4(4'-methyl-2,2'-bipyridyl)]-1,12-dodecane bridging ligand ("bb12") showed a high degree of selectivity for the nucleus of the eukaryotic cells. Additional co-localisation experiments with the general nucleic acid stain SYTO 9 indicated that the ruthenium complexes showed a considerable preference for the RNA-rich nucleolus, rather than chromosomal DNA. No significant differences were observed in the intracellular localisation between the ΔΔ and ΛΛ enantiomers of the dinuclear complex. Cytotoxicity assays carried out over 72 hours indicated that the ruthenium complexes, particularly the tri- and tetra-nuclear species, were significantly toxic to the eukaryotic cells. However, when the activity of the least cytotoxic compound (the ΔΔ enantiomer of the dinuclear species) was determined over a 24 hour period, the results indicated that the ruthenium complex was approximately a 100-fold less toxic to liver and kidney cells than to Gram positive bacteria. Circular dichroism (CD) spectroscopy was used to examine the effect of the ΔΔ and ΛΛ enantiomers of the dinuclear complex on the solution conformations of RNA and DNA. The CD experiments indicated that the RNA maintained the A-type conformation, and the DNA the B-type structure, upon binding by the ruthenium complexes.

  17. RNA and DNA binding of inert oligonuclear ruthenium(II) complexes in live eukaryotic cells.

    PubMed

    Li, Xin; Gorle, Anil K; Ainsworth, Tracy D; Heimann, Kirsten; Woodward, Clifford E; Collins, J Grant; Keene, F Richard

    2015-02-28

    Confocal microscopy was used to study the intracellular localisation of a series of inert polypyridylruthenium(II) complexes with three eukaryotic cells lines - baby hamster kidney (BHK), human embryonic kidney (HEK-293) and liver carcinoma (Hep-G2). Co-staining experiments with the DNA-selective dye DAPI demonstrated that the di-, tri- and tetra-nuclear polypyridylruthenium(II) complexes that are linked by the bis[4(4'-methyl-2,2'-bipyridyl)]-1,12-dodecane bridging ligand ("bb12") showed a high degree of selectivity for the nucleus of the eukaryotic cells. Additional co-localisation experiments with the general nucleic acid stain SYTO 9 indicated that the ruthenium complexes showed a considerable preference for the RNA-rich nucleolus, rather than chromosomal DNA. No significant differences were observed in the intracellular localisation between the ΔΔ and ΛΛ enantiomers of the dinuclear complex. Cytotoxicity assays carried out over 72 hours indicated that the ruthenium complexes, particularly the tri- and tetra-nuclear species, were significantly toxic to the eukaryotic cells. However, when the activity of the least cytotoxic compound (the ΔΔ enantiomer of the dinuclear species) was determined over a 24 hour period, the results indicated that the ruthenium complex was approximately a 100-fold less toxic to liver and kidney cells than to Gram positive bacteria. Circular dichroism (CD) spectroscopy was used to examine the effect of the ΔΔ and ΛΛ enantiomers of the dinuclear complex on the solution conformations of RNA and DNA. The CD experiments indicated that the RNA maintained the A-type conformation, and the DNA the B-type structure, upon binding by the ruthenium complexes. PMID:25333883

  18. Ruthenium(ii) complexes of hemilabile pincer ligands: synthesis and catalysing the transfer hydrogenation of ketones.

    PubMed

    Nair, Ashwin G; McBurney, Roy T; Walker, D Barney; Page, Michael J; Gatus, Mark R D; Bhadbhade, Mohan; Messerle, Barbara A

    2016-09-28

    A series of Ru(ii) complexes were synthesised based on a hemilabile pyrazole-N-heterocyclic carbene (NHC)-pyrazole (C3N2H3)CH2(C3N2H2)CH2(C3N2H3) NCN pincer ligand 1. All complexes were fully characterised using single crystal X-ray crystallography and multinuclear NMR spectroscopy. Hemilabile ligands provide flexible coordination modes for the coordinating metal ion which can play a significant effect on the efficiency and mechanism of catalysis by the resulting complex. Here we observed and isolated mono-, bi- and tri-dentate complexes of both Ag(i) and Ru(ii) with 1 in which the resultant coordination mode was controlled by careful reagent selection. The catalytic activity of the Ru(ii) complexes for the transfer hydrogenation reaction of acetophenone with isopropanol was investigated. The unexpected formation of the pentaborate anion, [B5O6(OH)4](-), during the synthesis of complex 6a was found to have an unexpected positive effect by enhancing the catalysis rate. This work provides insights into the roles that different coordination modes, counterions and ligand hemilability play on the catalytic activity in transfer hydrogenations. PMID:27539740

  19. Protein-binding, cytotoxicity in vitro and cell cycle arrest of ruthenium(II) polypyridyl complexes

    NASA Astrophysics Data System (ADS)

    Liu, Si-Hong; Zhu, Jian-Wei; Xu, Hui-Hua; Wang, Yan; Liu, Ya-Min; Liang, Jun-Bo; Zhang, Gui-Qiang; Cao, Di-Hua; Lin, Yang-Yang; Wu, Yong; Guo, Qi-Feng

    2016-05-01

    The cytotoxic activity of two Ru(II) complexes against A549, BEL-7402, HeLa, PC-12, SGC-7901 and SiHa cell lines was investigated by MTT method. Complexes 1 and 2 show moderate cytotoxicity toward BEL-7402 cells with an IC50 value of 53.9 ± 3.4 and 39.3 ± 2.1 μM. The effects of the complexes inducing apoptosis, cellular uptake, reactive oxygen species and mitochondrial membrane potential in BEL-7402 cells have been studied by fluorescence microscopy. The percentages of apoptotic and necrotic cells and cell cycle arrest were studied by flow cytometry. The BSA-binding behaviors were investigated by UV/visible and fluorescent spectra.

  20. Diniobium inverted sandwich complexes with μ-η6:η6-arene ligands: synthesis, kinetics of formation, and electronic structure.

    PubMed

    Gianetti, Thomas L; Nocton, Grégory; Minasian, Stefan G; Tomson, Neil C; Kilcoyne, A L David; Kozimor, Stosh A; Shuh, David K; Tyliszczak, Tolek; Bergman, Robert G; Arnold, John

    2013-02-27

    Monometallic niobium arene complexes [Nb(BDI)(N(t)Bu)(R-C(6)H(5))] (2a: R = H and 2b: R = Me, BDI = N,N'-diisopropylbenzene-β-diketiminate) were synthesized and found to undergo slow conversion into the diniobium inverted arene sandwich complexes [[(BDI)Nb(N(t)Bu)](2)(μ-RC(6)H(5))] (7a: R = H and 7b: R = Me) in solution. The kinetics of this reaction were followed by (1)H NMR spectroscopy and are in agreement with a dissociative mechanism. Compounds 7a-b showed a lack of reactivity toward small molecules, even at elevated temperatures, which is unusual in the chemistry of inverted sandwich complexes. However, protonation of the BDI ligands occurred readily on treatment with [H(OEt(2))][B(C(6)F(5))(4)], resulting in the monoprotonated cationic inverted sandwich complex 8 [[(BDI(#))Nb(N(t)Bu)][(BDI)Nb(N(t)Bu)](μ-C(6)H(5))][B(C(6)F(5))(4)] and the dicationic complex 9 [[(BDI(#))Nb(N(t)Bu)](2)(μ-RC(6)H(5))][B(C(6)F(5))(4)](2) (BDI(#) = (ArNC(Me))(2)CH(2)). NMR, UV-vis, and X-ray absorption near-edge structure (XANES) spectroscopies were used to characterize this unique series of diamagnetic molecules as a means of determining how best to describe the Nb-arene interactions. The X-ray crystal structures, UV-vis spectra, arene (1)H NMR chemical shifts, and large J(CH) coupling constants provide evidence for donation of electron density from the Nb d-orbitals into the antibonding π system of the arene ligands. However, Nb L(3,2)-edge XANES spectra and the lack of sp(3) hybridization of the arene carbons indicate that the Nb → arene donation is not accompanied by an increase in Nb formal oxidation state and suggests that 4d(2) electronic configurations are appropriate to describe the Nb atoms in all four complexes.

  1. An electrospray ionization tandem mass spectrometric study of p-tert-butylcalix[6]arene complexation with ammonium hydroxide, and ammonium and sodium ions.

    PubMed

    Sassine, André; Martins-Júnior, Helio A; Lebre, Daniel T; Valli, Felipe; Pires, Maria A F; Vega, Oscar; Felinto, Maria C F C

    2008-01-01

    The formation of complexes involving p-tert-butylcalix[6]arene with neutral and charged species has been investigated by tandem mass spectrometry combined with electrospray ionization. Complexes of p-tert-butylcalix[6]arene with NH4+ ions were observed in the ratios 1:1, 2:1, and 3:1, together with the complexes of p-tert-butylcalix[6]arene with NH4OH and Na+ ions in the ratios 1:1:1, 2:1:1, and 3:1:1. A single 1:1 complex of p-tert-butylcalix[6]arene with Na+ ions was observed. In addition, a doubly charged complex of p-tert-butylcalix[6]arene with NH4OH, Na+, and NH4+ ions in the ratio 6:1:1:1 was observed. The identity of each complex was determined by mass analysis of product ions formed by the application of a declustering potential over the range 20-220 V and by observation of product ion mass spectra wherein the collision energy was varied from 5 to 50 eV. Fragmentation of the complexes is characterized by the facile loss of the ammonia molecule, sodium and ammonium ions, loss of neutral p-tert-butylcalix[6]arene, and successive neutral losses of C4H8 from the six tert-butyl groups in each p-tert-butylcalix[6]arene molecule.

  2. Sticking and patching: tuning and anchoring cyclometallated ruthenium(II) complexes.

    PubMed

    Ertl, Cathrin D; Ris, Daniel P; Meier, Stefan C; Constable, Edwin C; Housecroft, Catherine E; Neuburger, Markus; Zampese, Jennifer A

    2015-01-28

    A series of [Ru(bpy)2(C^N)][PF6] (HC^N = 2-phenylpyridine derivative) complexes functionalized in the cyclometallating C^N phenyl ring with F, Me, OMe, CO2Me, S(t)Bu, SO2Me (ligands H1-H6) or in the C^N pyridine ring with 4-CO2Me or 4-C6H4P(O)(OEt)2 substituents (ligands H7 or H9) have been prepared and characterized; representative crystal structures confirm the structural features of the complexes. When the C^N ligand contains a CO2H substituent (ligand H28), deprotonation in addition to cyclometallation occurs to give a neutral, zwitter-ionic complex [Ru(bpy)2(8)]. The synthesis of the cationic complexes requires addition of a silver(i) salt (AgPF6 or AgBF4) to abstract Cl(-) from cis-[Ru(bpy)2Cl2] and (1)H NMR spectroscopic data are consistent with interactions between Ag(+) and the coordinated C^N ligand in [Ru(bpy)2(C^N)](+). The absorption spectra of [Ru(bpy)2(C^N)][PF6] (C^N = 1-6) are similar, but the introduction of the anchoring domains in [Ru(bpy)2(C^N)][PF6] with C^N = 7 or 9 enhances the absorption response; the greatest influence is observed in [Ru(bpy)2(9)](+) with the introduction of the 4-C6H4P(O)(OEt)2 substituent. Trends in emission and electrochemical behaviours of the complexes are interpreted in terms of the influence of the electronic properties of the C^N ligand substituents on the energies of the HOMO which is localized on the C^N ligand and Ru centre. This study provides an optimized synthetic route to the phosphonate ester derivative [Ru(bpy)2(9)][PF6], designed to anchor to a semiconductor surface; this complex also exhibits the most favourable absorption properties among the complexes studied.

  3. Synthesis, characterization and biological evaluation of novel Ru(II)-arene complexes containing intercalating ligands.

    PubMed

    Nikolić, Stefan; Rangasamy, Loganathan; Gligorijević, Nevenka; Aranđelović, Sandra; Radulović, Siniša; Gasser, Gilles; Grgurić-Šipka, Sanja

    2016-07-01

    Three new ruthenium(II)-arene complexes, namely [(η(6)-p-cymene)Ru(Me2dppz)Cl]PF6 (1), [(η(6)-benzene)Ru(Me2dppz)Cl]PF6 (2) and [(η(6)-p-cymene)Ru(aip)Cl]PF6 (3) (Me2dppz=11,12-dimethyldipyrido[3,2-a:2',3'-c]phenazine; aip=2-(9-anthryl)-1H-imidazo[4,5-f] [1,10] phenanthroline) have been synthesized and characterized using different spectroscopic techniques including elemental analysis. The complexes were found to be well soluble and stable in DMSO. The biological activity of the three complexes was tested in three different human cancer cell lines (A549, MDA-MB-231 and HeLa) and in one human non-cancerous cell line (MRC-5). Complexes 1 and 3, carrying η(6)-p-cymene as the arene ligand, were shown to be toxic in all cell lines in the low micromolar/subnanomolar range, with complex 1 being the most cytotoxic complex of the series. Flow cytometry analysis revealed that complex 1 caused concentration- and time-dependent arrest of the cell cycle in G2-M and S phases in HeLa cells. This event is followed by the accumulation of the sub-G1 DNA content after 48h, in levels higher than cisplatin and in the absence of phosphatidylserine externalization. Fluorescent microscopy and acridine orange/ethidium bromide staining revealed that complex 1 induced both apoptotic and necrotic cell morphology characteristics. Drug-accumulation and DNA-binding studies performed by inductively coupled plasma mass spectrometry in HeLa cells showed that the total ruthenium uptake increased in a time- and concentration-dependent manner, and that complex 1 accumulated more efficiently than cisplatin at equimolar concentrations. The introduction of a Me2dppz ligand into the ruthenium(II)-p-cymene scaffold was found to allow the discovery of a strongly cytotoxic complex with significantly higher cellular uptake and DNA-binding properties than cisplatin.

  4. Mirror-image organometallic osmium arene iminopyridine halido complexes exhibit similar potent anticancer activity.

    PubMed

    Fu, Ying; Soni, Rina; Romero, María J; Pizarro, Ana M; Salassa, Luca; Clarkson, Guy J; Hearn, Jessica M; Habtemariam, Abraha; Wills, Martin; Sadler, Peter J

    2013-11-01

    Four chiral Os(II) arene anticancer complexes have been isolated by fractional crystallization. The two iodido complexes, (S(Os),S(C))-[Os(η(6)-p-cym)(ImpyMe)I]PF6 (complex 2, (S)-ImpyMe: N-(2-pyridylmethylene)-(S)-1-phenylethylamine) and (R(Os),R(C))-[Os(η(6)-p-cym)(ImpyMe)I]PF6 (complex 4, (R)-ImpyMe: N-(2-pyridylmethylene)-(R)-1-phenylethylamine), showed higher anticancer activity (lower IC50 values) towards A2780 human ovarian cancer cells than cisplatin and were more active than the two chlorido derivatives, (S(Os),S(C))-[Os(η(6)-p-cym)(ImpyMe)Cl]PF6, 1, and (R(Os),R(C))-[Os(η(6)-p-cym)(ImpyMe)Cl]PF6, 3. The two iodido complexes were evaluated in the National Cancer Institute 60-cell-line screen, by using the COMPARE algorithm. This showed that the two potent iodido complexes, 2 (NSC: D-758116/1) and 4 (NSC: D-758118/1), share surprisingly similar cancer cell selectivity patterns with the anti-microtubule drug, vinblastine sulfate. However, no direct effect on tubulin polymerization was found for 2 and 4, an observation that appears to indicate a novel mechanism of action. In addition, complexes 2 and 4 demonstrated potential as transfer-hydrogenation catalysts for imine reduction.

  5. Spectroscopic studies of brilliant cresyl blue/water-soluble sulfonated calix[4]arene complex

    SciTech Connect

    Zhang, Y.; Pham, T.H.; Sanchez Pena, M.; Agbaria, R.A.; Warner, I.M.

    1998-07-01

    Water-soluble sulfonated calix[4]arene (SCX4) was used as the host molecule for the guest dye(probe), Brilliant Cresyl Blue (BCB), which is commonly employed for studies of various biological systems. Absorption and fluorescence techniques were employed for the analysis of this system. The formation of a complex between the BCB dye and SCX4 results in a decrease in the BCB fluorescence intensity. A study of the changes in absorption and of temperature effects on the fluorescence of BCB/SCX4 was conducted. The binding constant for BCB/SCX4 at room temperature was estimated to be 8.49{times}10{sup 3}thinspM{sup {minus}1}. {copyright} {ital 1998} {ital Society for Applied Spectroscopy}

  6. Charge-transfer luminescence from ruthenium(II) complexes containing tridentate ligands

    NASA Astrophysics Data System (ADS)

    Stone, M. L.; Crosby, G. A.

    Four complexes of the general formula Ru(NNN) 2+2 (N NN = tridentate N-heterocyclic ligand) were synthesized and studied spectroscopically. All exhibit visible absorption spectra that are charge-transfer-to-ligand in origin, are luminescent in glasses at 77 K, and display emission spectra that possess energies, structures, and decay tines that label them as charge transfer.

  7. Proton coupled electron transfer from the excited state of a ruthenium(II) pyridylimidazole complex.

    PubMed

    Pannwitz, Andrea; Wenger, Oliver S

    2016-04-28

    Proton coupled electron transfer (PCET) from the excited state of [Ru(bpy)2pyimH](2+) (bpy = 2,2'-bipyridine; pyimH = 2-(2'-pyridyl)imidazole) to N-methyl-4,4'-bipyridinium (monoquat, MQ(+)) was studied. While this complex has been investigated previously, our study is the first to show that the formal bond dissociation free energy (BDFE) of the imidazole-N-H bond decreases from (91 ± 1) kcal mol(-1) in the electronic ground state to (43 ± 5) kcal mol(-1) in the lowest-energetic (3)MLCT excited state. This makes the [Ru(bpy)2pyimH](2+) complex a very strong (formal) hydrogen atom donor even when compared to metal hydride complexes, and this is interesting for light-driven (formal) hydrogen atom transfer (HAT) reactions with a variety of different substrates. Mechanistically, formal HAT between (3)MLCT excited [Ru(bpy)2pyimH](2+) and monoquat in buffered 1 : 1 (v : v) CH3CN/H2O was found to occur via a sequence of reaction steps involving electron transfer from Ru(ii) to MQ(+) coupled to release of the N-H proton to buffer base, followed by protonation of reduced MQ(+) by buffer acid. Our study is relevant in the larger contexts of photoredox catalysis and light-to-chemical energy conversion. PMID:27094541

  8. Preparation and reactivity of mixed-ligand ruthenium(II) hydride complexes with phosphites and polypyridyls.

    PubMed

    Albertin, Gabriele; Antoniutti, Stefano; Bacchi, Alessia; D'Este, Claudia; Pelizzi, Giancarlo

    2004-02-23

    Chloro complexes [RuCl(N-N)P3]BPh4 (1-3) [N-N = 2,2'-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5'-dimethyl-2,2'-bipyridine, 5,5'-Me2bpy; P = P(OEt)3, PPh(OEt)2 and PPh2OEt] were prepared by allowing the [RuCl4(N-N)].H2O compounds to react with an excess of phosphite in ethanol. The bis(bipyridine) [RuCl(bpy)2[P(OEt)3

  9. New water-soluble ruthenium(II) cytotoxic complex: biological activity and cellular distribution.

    PubMed

    Morais, Tânia S; Santos, Filipa C; Jorge, Tiago F; Côrte-Real, Leonor; Madeira, Paulo J Amorim; Marques, Fernanda; Robalo, M Paula; Matos, António; Santos, Isabel; Garcia, M Helena

    2014-01-01

    A novel water soluble organometallic compound, [RuCp(mTPPMSNa)(2,2'-bipy)][CF3SO3] (TM85, where Cp=η(5)-cyclopentadienyl, mTPPMS=diphenylphosphane-benzene-3-sulfonate and 2,2'-bipy=2,2'-bipyridine) is presented herein. Studies of interactions with relevant proteins were performed to understand the behavior and mode of action of this complex in the biological environment. Electrochemical and fluorescence studies showed that TM85 strongly binds to albumin. Studies carried out to study the formation of TM85 which adducts with ubiquitin and cytochrome c were performed by electrospray ionization mass spectrometry (ESI-MS). Antitumor activity was evaluated against a variety of human cancer cell lines, namely A2780, A2780cisR, MCF7, MDAMB231, HT29, PC3 and V79 non-tumorigenic cells and compared with the reference drug cisplatin. TM85 cytotoxic effect was reduced in the presence of endocytosis modulators at low temperatures, suggesting an energy-dependent mechanism consistent with endocytosis. Ultrastructural analysis by transmission electron microscopy (TEM) revealed that TM85 targets the endomembranar system disrupting the Golgi and also affects the mitochondria. Disruption of plasma membrane observed by flow cytometry could lead to cellular damage and cell death. On the whole, the biological activity evaluated herein combined with the water solubility property suggests that complex TM85 could be a promising anticancer agent. PMID:24145065

  10. Synthesis, characterization and biological evaluation of labile intercalative ruthenium(ii) complexes for anticancer drug screening.

    PubMed

    Huang, Huaiyi; Zhang, Pingyu; Chen, Yu; Qiu, Kangqiang; Jin, Chengzhi; Ji, Liangnian; Chao, Hui

    2016-08-16

    DNA binding and DNA transcription inhibition is regarded as a promising strategy for cancer chemotherapy. Herein, chloro terpyridyl Ru(ii) complexes, [Ru(tpy)(N^N)Cl](+) (Ru1, N^N = 2,2'-bipyridine; Ru2, N^N = 3-(pyrazin-2-yl)-as-triazino[5,6-f]acenaphthylene; Ru3, N^N = 3-(pyrazin-2-yl)-as-triazino[5,6-f]phenanthrene; Ru4, N^N = 3-(pyrazin-2-yl)-as-triazino[5,6-f]pyrene) were prepared as DNA intercalative and covalent binding anticancer agents. The chloro ligand hydrolysis slowly and the octanol and water partition coefficient of Ru2-Ru4 were between 0.6 and 1.2. MALDI-TOF mass, DNA gel electrophoresis confirmed covalent and intercalative DNA binding modes of Ru2-Ru4, while Ru1 can only bind DNA covalently. As a result, Ru2-Ru4 exhibited stronger DNA transcription inhibition activity, higher cell uptake efficiency and better anticancer activity than Ru1. Ru4 was the most toxic complex toward all cancer cells which inhibited DNA replication and transcription. AO/EB, Annexin V/PI, nuclear staining, JC-1 assays further confirmed that Ru2-Ru4 induced cancer cell death by an apoptosis mechanism. PMID:27294337

  11. Tuning the hydrolytic aqueous chemistry of osmium arene complexes with N,O-chelating ligands to achieve cancer cell cytotoxicity.

    PubMed

    Peacock, Anna F A; Parsons, Simon; Sadler, Peter J

    2007-03-21

    Potential biological and medical applications of organometallic complexes are hampered by a lack of knowledge of their aqueous solution chemistry. We show that the hydrolytic and aqueous solution chemistry of half-sandwich OsII arene complexes of the type [(eta6-arene)Os(XY)Cl] can be tuned with XY chelating ligands to achieve cancer cell cytoxicity comparable to carboplatin. Complexes containing arene = p-cymene, XY = N,O-chelating ligands glycinate (1), L-alaninate (2), alpha-aminobutyrate (3), beta-alaninate (4), picolinate (5), or 8-hydroxyquinolinate (7) were synthesized. Although, 1-4 and 7 hydrolyzed rapidly (complexes with pi-acceptor pyridine as N-donor and carboxylate as O-donor (5 and 6) hydrolyzed much more slowly (t1/2 = 0.20 and 0.52 h, 298 K). The aqua picolinate complexes were more acidic (pKa* = 6.67, 6.33) than the other aqua adducts (pKa* = 7.17-7.71). At biological test concentrations (micromolar), the chelating ligands dissociated from complexes 1-4 to give the inert hydroxo-bridged dinuclear species [(eta6-arene)Os(mu-OH)3Os(eta6-arene)]+ (8), and these complexes were inactive toward human lung A549 and ovarian A2780 cancer cells. In contrast, 5-7 were cytotoxic, especially 6 (IC50 values of 8 and 4.2 microM). The X-ray structures of 9-ethylguanine, [(eta6-p-cym)Os(pico)(9EtG-N7)]PF6, and 9-ethyladenine, [(eta6-p-cym)Os(pico)(9EtA-N7)]PF6, adducts of 5 are reported (the first reported for G or A adducts of OsII). Crystals of the 9EtA complex contain homoadenine base pairing. The 9EtG adduct in particular exhibits remarkable aqueous kinetic stability. This work shows how the rational control of chemical reactivity (hydrolysis, acidity, formation of hydroxo-bridged dinuclear species) can allow the design of cytotoxic anticancer OsII arene complexes.

  12. Insights into anticancer activity and mechanism of action of a ruthenium(II) complex in human esophageal squamous carcinoma EC109 cells.

    PubMed

    Guo, Liubin; Lv, Gaochao; Qiu, Ling; Yang, Hui; Zhang, Li; Yu, Huixin; Zou, Meifen; Lin, Jianguo

    2016-09-01

    A ruthenium(II) complex [Ru(p-cymene)(NHC)Cl2] (NHC=1,3-bis(4-(tert-butyl)benzylimidazol-2-ylidene), referred to as L-4, has been designed and synthesized recently in order to look for new anticancer drugs with high efficacy and low side effects. The anticancer activity and mechanism of action of L-4 in human esophageal squamous carcinoma EC109 cells were systematically investigated. The results revealed that L-4 exerted strong inhibitory effect on the proliferation of EC109 cells, and it arrested EC109 cells at G2/M phase, accompanied with the up-regulation of p53 and p21 and the down-regulation of cyclin D1. The results also showed that the reactive oxygen species (ROS)-dependent apoptosis of EC109 can be induced by L-4 via inhibiting the activity of glutathione reductase (GR), decreasing the ratio of glutathione to oxidized glutathione (GSH/GSSG), and leading to the generation of reactive oxygen species. The mitochondria-mediated apoptosis of EC109 induced by L-4 was also observed from the increase of Bax/Bcl-2 ratio, overload of Ca(2+), disruption of mitochondrial membrane potential (MMP), redistribution of cytochrome c, and activation of caspase-3/-9. However, the effects of L-4 on the cell viability, GR activity, GSH/GSSG ratio, reactive oxygen species level, mitochondria dysfunction and apoptosis induction were remarkably attenuated by adding the reactive oxygen species scavenger, NAC. Therefore, it was concluded that L-4 can inhibit the proliferation of EC109 cells via blocking cell cycle progression and inducing reactive oxygen species-dependent and mitochondria-mediated apoptosis. These findings suggested that the ruthenium(II) complex might be a potential effective chemotherapeutic agent for human esophageal squamous carcinoma (ESCC) and worthy of further investigation. PMID:27262377

  13. Positional and compositional disorder in a ruthenium(II) piano-stool complex.

    PubMed

    Guzei, Ilia A; Dolinar, Brian S; Khumalo, Nozipho; Darkwa, James

    2013-08-01

    In (η⁶-p-cymene)(difluorophosphinato-κO){2-[(1H-pyrazol-1-yl)methyl-κN²]pyridine-κN}ruthenium(II) 0.85-hexafluorophosphate 0.15-tetrafluoroborate, [Ru(PO₂F₂)(C₁₀H₁₄)(C₉H₉N₃)](PF₆)0.85(BF₄)0.15, (I), the [PO₂F₂]⁻ ligand exhibits positional disorder due to one F atom and one O atom sharing the same two positions related by a mirror reflection across the O-P-F plane. The correct composition of this coordinated anion was successfully determined to be [PO₂F₂]⁻ by refining the complex with various tetrahedral anions in which terminal atoms have similar atomic form factors. The noncoordinated counter-ion is compositionally disordered between [PF₆]⁻ and [BF₄]⁻. The difficulty in determining the correct composition of this anion illustrates the importance of a crystallographer remaining impartial and open to encountering unexpected moieties in the process of elucidating a structure. PMID:23907873

  14. Evaluation of DNA binding, DNA cleavage, protein binding, radical scavenging and in vitro cytotoxic activities of ruthenium(II) complexes containing 2,4-dihydroxy benzylidene ligands.

    PubMed

    Mohanraj, Maruthachalam; Ayyannan, Ganesan; Raja, Gunasekaran; Jayabalakrishnan, Chinnasamy

    2016-12-01

    The new ruthenium(II) complexes with hydrazone ligands, 4-Methyl-benzoic acid (2,4-dihydroxy-benzylidene)-hydrazide (HL(1)), 4-Methoxy-benzoic acid (2,4-dihydroxy-benzylidene)-hydrazide (HL(2)), 4-Bromo-benzoic acid (2,4-dihydroxy-benzylidene)-hydrazide (HL(3)), were synthesized and characterized by various spectro analytical techniques. The molecular structures of the ligands were confirmed by single crystal X-ray diffraction technique. The DNA binding studies of the ligands and complexes were examined by absorption, fluorescence, viscosity and cyclic voltammetry methods. The results indicated that the ligands and complexes could interact with calf thymus DNA (CT-DNA) through intercalation. The DNA cleavage activity of the complexes was evaluated by gel electrophoresis assay, which revealed that the complexes are good DNA cleaving agents. The binding interaction of the ligands and complexes with bovine serum albumin (BSA) was investigated using fluorescence spectroscopic method. Antioxidant studies showed that the complexes have a strong radical scavenging properties. Further, the cytotoxic effect of the complexes examined on cancerous cell lines showed that the complexes exhibit significant anticancer activity. PMID:27612830

  15. Probing the Quenching of Quantum Dot Photoluminescence by Peptide-Labeled Ruthenium(II) Complexes.

    PubMed

    Scott, Amy M; Algar, W Russ; Stewart, Michael H; Trammell, Scott A; Blanco-Canosa, Juan B; Dawson, Philip E; Deschamps, Jeffrey R; Goswami, Ramasis; Oh, Eunkeu; Huston, Alan L; Medintz, Igor L

    2014-05-01

    Charge transfer processes with semiconductor quantum dots (QDs) have generated much interest for potential utility in energy conversion. Such configurations are generally nonbiological; however, recent studies have shown that a redox-active ruthenium(II)-phenanthroline complex (Ru(2+)-phen) is particularly efficient at quenching the photoluminescence (PL) of QDs, and this mechanism demonstrates good potential for application as a generalized biosensing detection modality since it is aqueous compatible. Multiple possibilities for charge transfer and/or energy transfer mechanisms exist within this type of assembly, and there is currently a limited understanding of the underlying photophysical processes in such biocomposite systems where nanomaterials are directly interfaced with biomolecules such as proteins. Here, we utilize redox reactions, steady-state absorption, PL spectroscopy, time-resolved PL spectroscopy, and femtosecond transient absorption spectroscopy (FSTA) to investigate PL quenching in biological assemblies of CdSe/ZnS QDs formed with peptide-linked Ru(2+)-phen. The results reveal that QD quenching requires the Ru(2+) oxidation state and is not consistent with Förster resonance energy transfer, strongly supporting a charge transfer mechanism. Further, two colors of CdSe/ZnS core/shell QDs with similar macroscopic optical properties were found to have very different rates of charge transfer quenching, by Ru(2+)-phen with the key difference between them appearing to be the thickness of their ZnS outer shell. The effect of shell thickness was found to be larger than the effect of increasing distance between the QD and Ru(2+)-phen when using peptides of increasing persistence length. FSTA and time-resolved upconversion PL results further show that exciton quenching is a rather slow process consistent with other QD conjugate materials that undergo hole transfer. An improved understanding of the QD-Ru(2+)-phen system can allow for the design of more

  16. Probing the Quenching of Quantum Dot Photoluminescence by Peptide-Labeled Ruthenium(II) Complexes

    PubMed Central

    2015-01-01

    Charge transfer processes with semiconductor quantum dots (QDs) have generated much interest for potential utility in energy conversion. Such configurations are generally nonbiological; however, recent studies have shown that a redox-active ruthenium(II)–phenanthroline complex (Ru2+-phen) is particularly efficient at quenching the photoluminescence (PL) of QDs, and this mechanism demonstrates good potential for application as a generalized biosensing detection modality since it is aqueous compatible. Multiple possibilities for charge transfer and/or energy transfer mechanisms exist within this type of assembly, and there is currently a limited understanding of the underlying photophysical processes in such biocomposite systems where nanomaterials are directly interfaced with biomolecules such as proteins. Here, we utilize redox reactions, steady-state absorption, PL spectroscopy, time-resolved PL spectroscopy, and femtosecond transient absorption spectroscopy (FSTA) to investigate PL quenching in biological assemblies of CdSe/ZnS QDs formed with peptide-linked Ru2+-phen. The results reveal that QD quenching requires the Ru2+ oxidation state and is not consistent with Förster resonance energy transfer, strongly supporting a charge transfer mechanism. Further, two colors of CdSe/ZnS core/shell QDs with similar macroscopic optical properties were found to have very different rates of charge transfer quenching, by Ru2+-phen with the key difference between them appearing to be the thickness of their ZnS outer shell. The effect of shell thickness was found to be larger than the effect of increasing distance between the QD and Ru2+-phen when using peptides of increasing persistence length. FSTA and time-resolved upconversion PL results further show that exciton quenching is a rather slow process consistent with other QD conjugate materials that undergo hole transfer. An improved understanding of the QD–Ru2+-phen system can allow for the design of more sophisticated

  17. Photoinduced processes within compact dyads based on triphenylpyridinium-functionalized bipyridyl complexes of ruthenium(II).

    PubMed

    Lainé, Philippe P; Ciofini, Ilaria; Ochsenbein, Philippe; Amouyal, Edmond; Adamo, Carlo; Bedioui, Fethi

    2005-06-01

    As an alternative to conventional charge-separation functional molecular models based on long-range ET within redox cascades, a "compact approach" has been examined. To this end, spacer elements usually inserted between main redox-active units within polyad systems have been removed, allowing extended rigidity but at the expense of enhanced intercomponent electronic communication. The molecular assemblies investigated here are of the P-(theta (1))-A type, where the theta (1) twist angle is related to the degree of conjugation between the photosensitizer (P, of {Ru(bpy)(3)}(2+) type) and the electron-acceptor (A). 4-N- and 4-N-,4'-N-(2,4,6-triphenylpyridinio)-2,2'-bipyridine ligands (A(1)-bpy and A(2)-bpy, respectively) have been synthesized to give complexes with Ru(II), 1-bpy and 2-bpy, respectively. Combined solid-state analysis (X-ray crystallography), solution studies ((1)H NMR, cyclic voltammetry) and computational structural optimization allowed verifying that theta (1) angle approaches 90 degrees within 1-bpy and 2-bpy in solution. Also, anticipated existence of strong intercomponent electronic coupling has been confirmed by investigating electronic absorption properties and electrochemical behavior of the compounds. The capability of 1-bpy and 2-bpy to undergo PET process was evaluated by carrying out their photophysical study (steady state emission and time-resolved spectroscopy at both 293 and 77 K). The conformational dependence of photoinduced processes within P-(theta (1))-A systems has been established by comparing the photophysical properties of 1-bpy (and 2-bpy) with those of an affiliated species reported in the literature, 1-phen. A complementary theoretical analysis (DFT) of the change of spin density distribution within model [1-bpy(theta (1))](-) mono-reduced species as a function of theta (1) has been undertaken and the possibility of conformationally switching emission properties of P was derived. PMID:15822134

  18. Highly reduced organometallics of the Group IV elements: Part One. The study of (trmpe) metal tetracarbonyl complexes of titanium, zirconium, and hafnium. Part Two. The study of bis-arene titanium complexes prepared from arene radical anions

    SciTech Connect

    Blackburn, D.W.

    1992-01-01

    Potassium naphthalenide reduction of solutions of the Group IV transition metal salts MCl[sub 4][center dot]THF, M = Ti, Zr, and Hf, in the presence of the tridentate phosphine ligand 1,1,1-tris(dimethylphosphinomethyl)ethane (trmpe), at -70[degrees] under Ar, followed by carbonylation at atmospheric pressure, provides the zerovalent carbonylphosphine complexes M(CO)[sub 4](trmpe). Yields range from 5% for Hf to 50% for Ti. The complexes were characterized by [sup 31]P and [sup 13]C NMR studies, and the Zr complex additionally by X-ray crystallography. The titanium complex reacts with triphenylstannide to displace one carbon monoxide ligand, forming the [(trmpe)Ti(CO)[sub 3](Sn(C[sub 6]H[sub 5])[sub 3])] anion. The reduction of TiCl[sub 4][center dot]2THF with arene radical anions provides bis-arene sandwich complexes in high yield (80-95%). For arene = naphthalene, the 18-electron [Ti(C[sub 10]H[sub 8])[sub 2

  19. Photorelease of Pyridyl Esters in Organometallic Ru(II) Arene Complexes.

    PubMed

    Habtemariam, Abraha; Garino, Claudio; Ruggiero, Emmanuel; Alonso-de Castro, Silvia; Mareque-Rivas, Juan C; Salassa, Luca

    2015-01-01

    New Ru(II) arene complexes of formula [(η6-p-cym)Ru(N-N)(X)]2+ (where p-cym = para-cymene, N-N = 2,2'-bipyrimidine (bpm) or 2,2'-bipyridine (bpy) and X = m/p-COOMe-Py, 1-4) were synthesised and characterized, including the molecular structure of complexes [(η6-p-cym)Ru(bpy)(m-COOMe-Py)]2+ (3) and [(η6-p-cym)Ru(bpy) (p-COOMe-Py)]2+ (4) by single-crystal X-ray diffraction. Complexes 1-4 are stable in the dark in aqueous solution over 48 h and photolysis studies indicate that they can photodissociate the monodentate m/p-COOMe-Py ligands selectively with yields lower than 1%. DFT and TD-DFT calculations (B3LYP/LanL2DZ/6-31G**) performed on singlet and triplet states pinpoint a low-energy triplet state as the reactive state responsible for the selective dissociation of the monodentate pyridyl ligands. PMID:25905605

  20. Structural Determinants of p53-Independence in Anticancer Ruthenium-Arene Schiff-Base Complexes.

    PubMed

    Chow, Mun Juinn; Babak, Maria V; Wong, Daniel Yuan Qiang; Pastorin, Giorgia; Gaiddon, Christian; Ang, Wee Han

    2016-07-01

    p53 is a key tumor suppressor gene involved in key cellular processes and implicated in cancer therapy. However, it is inactivated in more than 50% of all cancers due to mutation or overexpression of its negative regulators. This leads to drug resistance and poor chemotherapeutic outcome as most clinical drugs act via a p53-dependent mechanism of action. An attractive strategy to circumvent this resistance would be to identify new anticancer drugs that act via p53-independent mode of action. In the present study, we identified 9 Ru (II)-Arene Schiff-base (RAS) complexes able to induce p53-independent cytotoxicity and discuss structural features that are required for their p53-independent activity. Increasing hydrophobicity led to an increase in cellular accumulation in cells with a corresponding increase in efficacy. We further showed that all nine complexes demonstrated p53-independent activity. This was despite significant differences in their physicochemical properties, suggesting that the iminoquinoline ligand, a common structural feature for all the complexes, is required for the p53-independent activity.

  1. Can metal ion complexation compete with the self-assembly processes of calix[4]arene amine derivatives?

    PubMed

    O'Toole, Laura; Creaven, Bernadette S; McGinley, John

    2014-06-14

    Self-assembly can occur spontaneously through aryl-aryl π-stacking in solution for calix[4]arenes derivatised at both the upper and lower rims with pendant aromatic rings, including pyridine rings. It was hoped that metal ion complexation would help to control the level of self-assembly occurring in solution, by disrupting these interactions. Metal ion titration studies were carried out on 3 with various zinc salts, but it was found that even with 1 : 4 ligand to metal ratio, the self-assembly process still dominated. Furthermore, in an effort to prevent the self-assembly process, the lower rim was completely substituted, but metal complexation reactions with these fully substituted calix[4]arenes still showed that the self-assembly process dominated. PMID:24740409

  2. Evaluation of DNA-binding, DNA cleavage, antioxidant and cytotoxic activity of mononuclear ruthenium(II) carbonyl complexes of benzaldehyde 4-phenyl-3-thiosemicarbazones

    NASA Astrophysics Data System (ADS)

    Sampath, Krishnan; Sathiyaraj, Subbaiyan; Jayabalakrishnan, Chinnasamy

    2013-11-01

    Two 4-phenyl-3-thiosemicarbazone ligands, (E)-2-(2-chlorobenzylidene)-N-phenylhydrazinecarbothioamide (HL1) and (E)-2-(2-nitrobenzylidene)-N-phenylhydrazinecarbothioamide (HL2), and its ruthenium(II) complexes were synthesized and characterized by physico-chemical and spectroscopic methods. The Schiff bases act as bidentate, monobasic chelating ligands with S and N as the donor sites and are preferably found in the thiol form in all the complexes studied. The molecular structure of HL1 and HL2 were determined by single crystal X-ray diffraction method. DNA binding of the compounds was investigated by absorption spectroscopy which indicated that the compounds bind to DNA via intercalation. The oxidative cleavage of the complexes with CT-DNA inferred that the effects of cleavage are dose dependent. Antioxidant study of the ligands and complexes showed significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of the ligands and complexes assayed against HeLa and MCF-7 cell lines showed higher cytotoxic activity with the lower IC50 values indicating their efficiency in killing the cancer cells even at low concentrations.

  3. Troponate/Aminotroponate Ruthenium-Arene Complexes: Synthesis, Structure, and Ligand-Tuned Mechanistic Pathway for Direct C-H Bond Arylation with Aryl Chlorides in Water.

    PubMed

    Dwivedi, Ambikesh D; Binnani, Chinky; Tyagi, Deepika; Rawat, Kuber S; Li, Pei-Zhou; Zhao, Yanli; Mobin, Shaikh M; Pathak, Biswarup; Singh, Sanjay K

    2016-07-01

    A series of water-soluble troponate/aminotroponate ruthenium(II)-arene complexes were synthesized, where O,O and N,O chelating troponate/aminotroponate ligands stabilized the piano-stool mononuclear ruthenium-arene complexes. Structural identities for two of the representating complexes were also established by single-crystal X-ray diffraction studies. These newly synthesized troponate/aminotroponate ruthenium-arene complexes enable efficient C-H bond arylation of arylpyridine in water. The unique structure-activity relationship in these complexes is the key to achieve efficient direct C-H bond arylation of arylpyridine. Moreover, the steric bulkiness of the carboxylate additives systematically directs the selectivity toward mono- versus diarylation of arylpyridines. Detailed mechanistic studies were performed using mass-spectral studies including identification of several key cyclometalated intermediates. These studies provided strong support for an initial cycloruthenation driven by carbonate-assisted deprotonation of 2-phenylpyridine, where the relative strength of η(6)-arene and the troponate/aminotroponate ligand drives the formation of cyclometalated 2-phenylpyridine Ru-arene species, [(η(6)-arene)Ru(κ(2)-C,N-phenylpyridine) (OH2)](+) by elimination of troponate/aminotroponate ligands and retaining η(6)-arene, while cyclometalated 2-phenylpyridine Ru-troponate/aminotroponate species [(κ (2)-troponate/aminotroponate)Ru(κ(2)-C,N-phenylpyridine)(OH2)2] was generated by decoordination of η(6)-arene ring during initial C-H bond activation of 2-phenylpyridine. Along with the experimental mass-spectral evidence, density functional theory calculation also supports the formation of such species for these complexes. Subsequently, these cycloruthenated products activate aryl chloride by facile oxidative addition to generate C-H arylated products. PMID:27305143

  4. Troponate/Aminotroponate Ruthenium-Arene Complexes: Synthesis, Structure, and Ligand-Tuned Mechanistic Pathway for Direct C-H Bond Arylation with Aryl Chlorides in Water.

    PubMed

    Dwivedi, Ambikesh D; Binnani, Chinky; Tyagi, Deepika; Rawat, Kuber S; Li, Pei-Zhou; Zhao, Yanli; Mobin, Shaikh M; Pathak, Biswarup; Singh, Sanjay K

    2016-07-01

    A series of water-soluble troponate/aminotroponate ruthenium(II)-arene complexes were synthesized, where O,O and N,O chelating troponate/aminotroponate ligands stabilized the piano-stool mononuclear ruthenium-arene complexes. Structural identities for two of the representating complexes were also established by single-crystal X-ray diffraction studies. These newly synthesized troponate/aminotroponate ruthenium-arene complexes enable efficient C-H bond arylation of arylpyridine in water. The unique structure-activity relationship in these complexes is the key to achieve efficient direct C-H bond arylation of arylpyridine. Moreover, the steric bulkiness of the carboxylate additives systematically directs the selectivity toward mono- versus diarylation of arylpyridines. Detailed mechanistic studies were performed using mass-spectral studies including identification of several key cyclometalated intermediates. These studies provided strong support for an initial cycloruthenation driven by carbonate-assisted deprotonation of 2-phenylpyridine, where the relative strength of η(6)-arene and the troponate/aminotroponate ligand drives the formation of cyclometalated 2-phenylpyridine Ru-arene species, [(η(6)-arene)Ru(κ(2)-C,N-phenylpyridine) (OH2)](+) by elimination of troponate/aminotroponate ligands and retaining η(6)-arene, while cyclometalated 2-phenylpyridine Ru-troponate/aminotroponate species [(κ (2)-troponate/aminotroponate)Ru(κ(2)-C,N-phenylpyridine)(OH2)2] was generated by decoordination of η(6)-arene ring during initial C-H bond activation of 2-phenylpyridine. Along with the experimental mass-spectral evidence, density functional theory calculation also supports the formation of such species for these complexes. Subsequently, these cycloruthenated products activate aryl chloride by facile oxidative addition to generate C-H arylated products.

  5. Synthesis of bismuth and antimony complexes of the "larger" calix[n]arenes (n=6-8); from mononuclear to tetranuclear complexes.

    PubMed

    Mendoza-Espinosa, Daniel; Rheingold, Arnold L; Hanna, Tracy A

    2009-07-14

    A series of calix[n]arene (n=6-8) bismuth and antimony complexes were synthesized and fully characterized by NMR, X-ray, IR, UV-Vis and elemental analysis. The monobismuth calix[6]arene complex [Bi{tBuC6(H)3}]2 1 was prepared by the reaction of para-tert-butylcalix[6]arene (tBuC6(H)6) with one equivalent of Bi[N(SiMe3)2]3. Complex 1 featured a Bi2(micro-O)2 central core similar to other bismuth calixarene complexes prepared by our group. Reaction of calix[6]arene (HC6(H)6) with two equivalents of Bi(OtBu)3 yielded different outcomes depending on the reaction solvent. If THF was used, complex [Bi{HC6(H)3}] 2 was obtained in 72% yield; however, when toluene was used, complexes 2 and [Bi2{HC6}] 3 were isolated in 23 and 57% yields, respectively. Mononuclear complexes 1 and 2 displayed dimeric structures in the solid state with cone-like conformations for the calixarene ligands. The 1H NMR spectrum of complex 2 displays patterns for an asymmetric structure with two signals in a 2:1 ratio for the unreacted OH groups. Treatment of calix[6]arenes RC6(H)6 (R=H, tBu) with two equivalents of SbR3 (R=OtBu, NMe2) produced dinuclear complexes [Sb2{HC6}] 4, and [Sb2{tBuC6}] 5, respectively. The 1H NMR spectra for the dinuclear complexes 3, 4, and 5 showed the characteristic calixarene pattern for a 1,2,3-alternate conformer. In the process of recrystallization of complex 4 an unexpected trimetallic complex with composition [Sb3O2{HC6(H)}] 4a was obtained in low yield. Treatment of para-tert-butylcalix[7]arene (tBuC7(H)7) with two equivalents of Bi(OtBu)3 produced the bimetallic complex [Bi2O{tBuC7(H)3}]2 6. Complex 6 contains an overall Bi4O2(OAr)8 core system with a structural resemblance to other bimetallic bismuth calixarene complexes reported by our group. The larger para-benzylcalix[8]arene (BnC8(H)8) and calix[8]arene (HC8(H)8) reacted with excess Bi(OtBu)3 to produce the tetranuclear complexes [Bi4O2{HC8}] 7 and [Bi4O2{BnC8}] 8, respectively. The solid state structure of

  6. Pb, Sr and Ba calix[6]arene hexacarboxylic acid octahedral complexation: a dramatic effect of dealkylation

    PubMed Central

    Adhikari, Birendra Babu; To, Cuong-Alexander; Iwasawa, Tetsuo; Schramm, Michael P.

    2015-01-01

    Calix[6]arene hexacarboxylic acid binds instantly and with low symmetry to Pb, Sr and Ba. Later a highly symmetric up-down alternating conformation emerges. The solution structures are identical to their p-tert-butylcalix[6]arene hexacarboxylic acid counterparts. With either receptor an octahedral cage is formed around the metal. The transformation from low to high symmetry however proceeds at significantly faster rates for the de-t-butylated host. PMID:26752941

  7. An investigation of the photochemical properties of transition metal arene complexes: Final report for the period July 1, 1983 to June 30, 1987

    SciTech Connect

    Mann, K.R.

    1987-08-01

    The photochemical removal of the arene from CpM(eta/sup 6/-arene)/sup +/ was studied for complexes of Fe(II) and Ru(II); (Fe, arene = p-dichlorobenzene, benzene, toluene, d/sub 8/-toluene, p-xylene, mesitylene, durene, pentamethylbenzene, hexamethylbenzene, hexaethylbenzene, and tri-t-butylbenzene; Ru, p-dichlorobenzene, benzene, toluene, mesitylene, pentamethylbenzene, hexamethylbenzene, and tri-t-butylbenzene). Quantum yields were determined. The photoactive state was identified as the distorted a/sup 3/E/sub 1/ ligand field excited state. The excited state energy of the Fe complexes lies about 14,000 cm/sup -1/ above ground state. A theoretical photophysical model was developed to relate the quantum yield for arene release to the rate of arene release. This model predicts a linear correlation between log((phi/1-phi)) and sigma/sub p/, the Hammett parameter if electronic effects at the arene influence the rate of arene substitution. For chloro and methyl substituted arenes (up to 5 substituents for Fe and 6 substituents for Ru), the linear correlation was verified. The Hammett rho parameter is +1.03 and +0.53 for the Fe complexes in CH/sub 2/Cl/sub 2/ and CH/sub 3/CN solution respectively; for the Ru complexes in CH/sub 3/CN solution rho = +1.38. These data indicate a small negative charge builds up at the arene in the transition state for the arene release reaction. Deviations from the linear correlation of log(phi/(1-phi)) with sigma/sub p/ were found for the sterically hindered CpFe(eta/sup 6/-HMB)/sup +/, CpFe(eta/sup 6/-HEB)/sup +/ and CpFe(eta/sup 6/-1,3,5-tri-t-butylbenzene)/sup +/ complexes (HMB = hexamethylbenzene; HEB = hexaethylbenzene). These deviations result from steric interactions that hinder the interaction of nucleophiles in the transition state and ultimately control the quantum yield of arene release for a given complex.

  8. Bis-N-heterocyclic carbene (NHC) stabilized η6-arene iron(0) complexes: synthesis, structure, reactivity, and catalytic activity.

    PubMed

    Blom, Burgert; Tan, Gengwen; Enthaler, Stephan; Inoue, Shigeyoshi; Epping, Jan Dirk; Driess, Matthias

    2013-12-01

    Reaction of FeCl2 with the chelating bis-N-heterocyclic carbene (NHC) bis-(N-Dipp-imidazole-2-ylidene)methylene (abbreviated {((Dipp)C:)2CH2}) (Dipp = 2,6-di-isopropylphenyl) affords the complex [FeCl2{((Dipp)C:)2CH2}] (1) in high yield. Reduction of complex 1 with excess KC8 with a 10-fold molar excess of PMe3 affords the Fe(II) complex [FeH{((Dipp)C:)2CH2}(PMe3)(η(2)-PMe2CH2)] (2) as a mixture of three stereoisomers. Complex 2, the first example of any iron(II) complex bearing mutually an NHC and PMe3 ligand, is likely obtained from the in situ, reductively generated 16 VE Fe(0) complex, [Fe{((Dipp)C:)2CH2}(PMe3)2] (2'), following intramolecular C-H activation of one of the phosphorus-bound CH3 groups. Complex 2 is unstable in aromatic solvents and forms, via a novel synthetic transformation involving intramolecular reductive elimination and concomitant PMe3 elimination, the Fe (0) arene complex [Fe{((Dipp)C:)2CH2}(η(6)-C6D6)] (4-d6) in C6D6. Complex 4-d6 represents the first example of an NHC stabilized iron (0) arene complex. The transformation from 2 to 4-d6 can be accelerated at higher temperature and at 60 °C forms immediately. Alternatively, the reduction of 1 in the presence of toluene or benzene affords the complexes [Fe{((Dipp)C:)2CH2}(η(6)-C7H8)] (3) and [Fe{((Dipp)C:)2CH2}(η(6)-C6H6)] (4), selectively and in good yields. DFT calculations characterizing the bonding situation in 3 and 4 reveal similar energies of the HOMO and LUMO orbitals, with the LUMO orbital of both complexes located on the Dipp rings of the bis-NHC. The HOMO orbital reflects a π-back-bonding interaction between the Fe(0) center and the chelating NHC ligand, while the HOMO-1 is associated with the arene interaction with the Fe(0) site. The calculations do not suggest any noninnocence of the coordinated arene in either complex. Moreover, the (57)Fe Mössbauer spectrum of 4 at 80K exhibits parameters (δ = 0.43 mm·s(-1); ΔEQ = 1.37 mm·s(-1)) which are consistent with a five

  9. Laser Spectroscopic and Theoretical Studies of Encapsulation Complexes of Calix[4]arene

    SciTech Connect

    Kaneko, Shohei; Inokuchi, Yoshiya; Ebata, Takayuki; Apra, Edoardo; Xantheas, Sotiris S.

    2011-10-13

    The complexes between the host calix[4]arene (C4A) and various guest molecules such as NH3, N2, CH4, and C2H2 have been investigated via experimental and theoretical methods. The S1-S0 electronic spectra of these guest-host complexes are observed by mass-selected resonant two-photon ionization (R2PI) and laser induced fluorescence (LIF) spectroscopy. The infrared (IR) spectra of the complexes formed in molecular beams are obtained by IR-UV double resonance (IR-UV DR) and IR photodissociation (IRPD) spectroscopy. The supramolecular structures of the complexes are investigated by electronic structure methods (density functional and second order perturbation theory). The current results for the various molecular guests are put in perspective with the previously reported ones for the C4A-Rare Gas (Rg) (Phys. Chem. Chem. Phys. 2007, 126, 141101) and C4A-H2O complexes (J. Phys. Chem. A, 2010, 114, 2967). The electronic spectra of the complexes of C4A with N2, CH4 and C2H2 exhibit red-shifts of similar magnitudes with the ones observed for the C4A-Rg complexes, whereas the complexes of C4A with H2O and NH3 show much larger red-shifts. Most of the IR-UV DR spectra of the complexes, except for C4A-C2H2, show a broad hydrogen bonded OH stretching band with a peak at ~3160 cm-1. The analysis of the experimental results, in agreement with the ones resulted from the electronic structure calculations, suggest that C4A preferentially forms endo-complexes with all the guest species reported in this study. We discuss the similarities and differences of the structures, binding energies and the nature of the interaction between the C4A host and the various guest species. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy

  10. Unexpected high photothemal conversion efficiency of gold nanospheres upon grafting with two-photon luminescent ruthenium(II) complexes: A way towards cancer therapy?

    PubMed

    Zhang, Pingyu; Wang, Jinquan; Huang, Huaiyi; Yu, Bole; Qiu, Kangqiang; Huang, Juanjuan; Wang, Shutao; Jiang, Lei; Gasser, Gilles; Ji, Liangnian; Chao, Hui

    2015-09-01

    The design and development of functional hybrid nanomaterials is currently a topic of great interest in biomedicine. Herein we investigated the grafting of Ru(II) polypyridyl complexes onto gold nanospheres (Ru@AuNPs) to improve the particles' near infrared (NIR) absorption, and ultimately allow for application in photothermal cancer therapy. As demonstrated in this article, these ruthenium(II) complexes could indeed significantly enhance gold nanospheres' two-photon luminescence (PTL) intensity and photothermal therapy (PTT) efficiency. The best dual functional nanoparticles of this study were successfully used for real-time luminescent imaging-guided PTT in live cancer cells. Furthermore, in vivo tumor ablation was achieved with excellent treatment efficacy under a diode laser (808 nm) irradiation at the power density of 0.8 W/cm(2) for 5 min. This study demonstrates that the coupling of inert Ru(II) polypyridyl complexes to gold nanospheres allows for the enhancement of two-photon luminescence and for efficient photothermal effect.

  11. Ruthenium(II) bipyridine complexes bearing quinoline-azoimine (NN‧N″) tridentate ligands: Synthesis, spectral characterization, electrochemical properties and single-crystal X-ray structure analysis

    NASA Astrophysics Data System (ADS)

    Al-Noaimi, Mousa; Abdel-Rahman, Obadah S.; Fasfous, Ismail I.; El-khateeb, Mohammad; Awwadi, Firas F.; Warad, Ismail

    Four octahedral ruthenium(II) azoimine-quinoline complexes having the general molecular formula [RuII(Lsbnd Y)(bpy)Cl](PF6) {Lsbnd Y = YC6H4Ndbnd NC(COCH3)dbnd NC9H6N, Y = H (1), CH3 (2), Br (3), NO2 (4) and bpy = 2,2‧-bipyrdine} were synthesized. The azoimine-quinoline based ligands behave as NN‧N″ tridentate donors and coordinated to ruthenium via azo-N‧, imine-N‧ and quinolone-N″ nitrogen atoms. The composition of the complexes has been established by elemental analysis, spectral methods (FT-IR, electronic, 1H NMR, UV/Vis and electrochemical (cyclic voltammetry) techniques. The crystal structure of complex 1 is reported. The Ru(II) oxidation state is greatly stabilized by the novel tridentate ligands, showing Ru(III/II) couples ranging from 0.93-1.27 V vs. Cp2Fe/Cp2Fe+. The absorption spectrum of 1 in dichloromethane was modeled by time-dependent density functional theory (TD-DFT).

  12. Metal arene complexes in coal structure determination: Quarterly report for the period December 1986-February 1987. [Hexamethylbenzenetricarbonylchromium anion

    SciTech Connect

    Woolsey, N.F.

    1987-03-01

    The development of arene metal (Cr, Fe) complex chemistry has continued this quarter. Peroxidation of the pentamethylbenzene tricarbonylchromium anion was definitely established not to give a phenolic product. The products of 1,3-dipolar cycloaddition of ozone and ethylazidoformate with a zwitterionic iron complex were identified and quantified. The product of a rhodium complex reaction with a useful ligand was established by x-ray crystal structure determination to not involve the desired carbon-carbon bond insertion reaction. Modification of the above procedures to facilitate the desired aryl-benzylic carbon detachment are under way.

  13. Upconverting Nanoparticles Prompt Remote Near-Infrared Photoactivation of Ru(II)-Arene Complexes.

    PubMed

    Ruggiero, Emmanuel; Garino, Claudio; Mareque-Rivas, Juan C; Habtemariam, Abraha; Salassa, Luca

    2016-02-18

    The synthesis and full characterisation (including X-ray diffraction studies and DFT calculations) of two new piano-stool Ru(II) -arene complexes, namely [(η(6) -p-cym)Ru(bpy)(m-CCH-Py)][(PF)6]2 (1) and [(η(6) -p-cym)Ru(bpm)(m-CCH-Py)][(PF)6]2 (2; p-cym=p-cymene, bpy=2,2'-bipyridine, bpm=2,2'-bipyrimidine, and m-CCH-Py=3-ethynylpyridine), is described and discussed. The reaction of the m-CCH-Py ligand of 1 and 2 with diethyl-3-azidopropyl phosphonate by Cu-catalysed click chemistry affords [(η(6) -p-cym)Ru(bpy)(P-Trz-Py)][(PF)6]2 (3) and [(η(6) -p-cym)Ru(bpm)(P-Trz-Py)][(PF)6]2 (4; P-Trz-Py=[3-(1-pyridin-3-yl-[1,2,3]triazol-4-yl)-propyl]phosphonic acid diethyl ester). Upon light excitation at λ=395 nm, complexes 1-4 photodissociate the monodentate pyridyl ligand and form the aqua adduct ions [(η(6) -p-cym)Ru(bpy)(H2O)](2+) and [(η(6) -p-cym)Ru(bpm)(H2O)](2+). Thulium -doped upconverting nanoparticles (UCNPs) are functionalised with 4, thus exploiting their surface affinity for the phosphonate group in the complex. The so-obtained nanosystem UCNP@4 undergoes near-infrared (NIR) photoactivation at λ=980 nm, thus producing the corresponding reactive aqua species that binds the DNA-model base guanosine 5'-monophosphate. PMID:26785101

  14. Crystal Structure of an L-Carnitine Complex with Pyrogallol[4]arene

    NASA Astrophysics Data System (ADS)

    Fujisawa, I.; Takeuchi, D.; Kitamura, Y.; Okamoto, R.; Aoki, K.

    2012-03-01

    L-Carnitine is essential for the transport of long-chain fatty acids from cytosol into mitochondria for generating metabolic energy. The survey of crystal structures of carnitine-containing proteins in the Protein Data Bank reveals that carnitine can take several conformations with the quarternary trimethylammonium terminal being always bound to aromatic residues through cation-π interactions in acyltransferases or carnitine-binding proteins. In order to demonstrate the importance of cation-π interaction as a carnitine recognition mechanism in the artificial receptor-ligand system that mimics the carnitine-binding sites, we have determined the crystal structure of a complex formed between L-carnitine and pyrogallol[4]arene (pyrogallol cyclic tetramer: PCT) as a carnitine receptor, 2PCT·2(L-carnitine)·4EtOH. There form two crystallographically independent monomeric [PCT·L-carnitine] substructures, which further form an obliquely arranged capsule-like dimeric [PCT·L-carnitine]2 structure through a pair of O-H (PCT)···O (L-carnitine) hydrogen bonds. This is the first report of PCT complex with chiral molecules. In each of the two monomeric [PCT·L-carnitine] substructures, the L-carnitine molecule takes the elongated form with an intramolecular hydrogen bond between the hydroxyl group and the carboxylate oxygen, and the cationic trimethylammonium moiety is incorporated into the cavity of the bowl-shaped PCT molecule through cation-π interactions. These features are similar to those at the D-carnitine-binding site in the crystal structure of the glycine betaine/carnitine/choline-binding protein complex.

  15. Synthesis, structure, photophysics, electrochemistry, and ion-binding studies of ruthenium(II) 1,10-phenanthroline complexes containing thia-, selena-, and aza-crown pendants.

    PubMed

    Li, Mei-Jin; Chu, Ben Wai-Kin; Zhu, Nianyong; Yam, Vivian Wing-Wah

    2007-02-01

    A series of ruthenium(II) diimine complexes containing thia-, selena- and aza-crowns derived from 1,10-phenanthroline have been synthesized and characterized, and their photophysics and electrochemistry were studied. Their interaction with metal ions was investigated by UV-vis, luminescence, and 1H NMR spectroscopy. The crystal structures of [Ru(bpy)2(L1)](PF6)2, [Ru(bpy)2(L2)](ClO4)2, [Ru(bpy)2(L3)](ClO4)2, and [Ru(bpy)2(L4)](ClO4)2 have been determined. The luminescence properties of [Ru(bpy)2(L1)](ClO4)2 were found to be sensitive and selective toward the presence of Hg2+ ions in an acetonitrile solution. The addition of alkaline-earth metal ions, Zn2+, Cd2+, and Hg2+ ions, to the solution of [Ru(bpy)2(L6)](ClO4)2 in acetonitrile gave rise to large changes in the UV-vis and emission spectra. The binding of metal ions to [Ru(bpy)2(L6)](ClO4)2 was found to cause a strong enhancement in the emission intensities of the complex, with high specificity toward Hg2+ ions.

  16. Efficient complexation between pillar[5]arenes and neutral guests: from host-guest chemistry to functional materials.

    PubMed

    Wang, Yiliang; Ping, Guchuan; Li, Chunju

    2016-08-01

    Since their discovery in 2008, pillar[n]arenes have been a popular family of macrocyclic arene hosts due to their accessible one-step synthesis, convenient functionalization, symmetrical prism structures and perfect cavity host-guest properties. Compared with other macrocyclic hosts, the most peculiar recognition behavior of pillararenes is the strong binding affinities of pillar[5]arenes (P5As) towards neutral guests in organic media, which is unfeasible for classic crown ethers and calixarenes. The intriguing properties have found extensive applications in many fields from supramolecular chemistry to materials science. This feature article provides a detailed summary of the molecular recognition of P5As and neutral guests, where the driving forces, binding mechanisms, and binding selectivities are comprehensively discussed. Furthermore, brief highlights of research progress in the functional applications based on the neutral guest⊂P5A motifs were also discussed, including the construction of complex topological superstructures (e.g. rotaxanes, catenanes and daisy chains), supramolecular polymers, and functional materials. PMID:27351168

  17. Asymmetric Hydrogenation of Unprotected Indoles Catalyzed by η(6)-Arene/N-Me-sulfonyldiamine-Ru(II) Complexes.

    PubMed

    Touge, Taichiro; Arai, Takayoshi

    2016-09-01

    Protecting-group-free transformation is a challenging and important issue in atom-economical organic synthesis. The η(6)-arene/N-Me-sulfonyldiamine-Ru(II)-BF4 complex-catalyzed asymmetric hydrogenation of 2-substituted unprotected indoles in weakly acidic hexafluoroisopropanol gives optically active indoline compounds with up to >99% ee. Under mild reaction media, halogen atoms and synthetically important protecting groups (e.g., silyl ether, acetal, benzyl ether, and ester) on indoles are maintained, which is advantageous for the synthesis of further complex indoline molecules. PMID:27509089

  18. Synthesis, reactivity studies, structural aspects, and solution behavior of half sandwich ruthenium(II) N,N',N''-triarylguanidinate complexes.

    PubMed

    Singh, Taruna; Kishan, Ram; Nethaji, Munirathinam; Thirupathi, Natesan

    2012-01-01

    pair with C═Nπ* orbital of the imine unit. Complexes 1, 2, 5, 6, 8·H(2)O, and 9 were shown to exist as a single isomer in solution as revealed by NMR data, and this was ascribed to a fast C-N(H)Ar bond rotation caused by a less bulky aryl moiety in these complexes. In contrast, 3 and 10 were shown to exist as a mixture of three and five isomers in about 1:1:1 and 1·0:1·2:2·7:3·5:6·9 ratios, respectively in solution as revealed by a VT (1)H NMR, (1)H-(1)H COSY in conjunction with DEPT-90 (13)C NMR data measured at 233 K in the case of 3. The multiple number of isomers in solution was ascribed to the restricted C-N(H)(o-tolyl) bond rotation caused by the bulky o-tolyl substituent in 3 or the aforementioned restricted C-NH(o-tolyl) bond rotation as well as the restricted ruthenium-arene(centroid) bond rotation caused by the substituents around the ruthenium atom in 10.

  19. A ruthenium(II) complex as turn-on Cu(II) luminescent sensor based on oxidative cyclization mechanism and its application in vivo

    PubMed Central

    Zhang, Yunfei; Liu, Zonglun; Yang, Kui; Zhang, Yi; Xu, Yongqian; Li, Hongjuan; Wang, Chaoxia; Lu, Aiping; Sun, Shiguo

    2015-01-01

    Copper ions play a vital role in a variety of fundamental physiological processes not only in human beings and plants, but also for extensive insects and microorganisms. In this paper, a novel water-soluble ruthenium(II) complex as a turn-on copper(II) ions luminescent sensor based on o-(phenylazo)aniline was designed and synthesized. The azo group would undergo a specific oxidative cyclization reaction with copper(II) ions and turn into high luminescent benzotriazole, triggering significant luminescent increasements which were linear to the concentrations of copper(II) ions. The sensor distinguished by its high sensitivity (over 80-fold luminescent switch-on response), good selectivity (the changes of the emission intensity in the presence of other metal ions or amino acids were negligible) and low detection limit (4.42 nM) in water. Moreover, the copper(II) luminescent sensor exhibited good photostability under light irradiation. Furthermore, the applicability of the proposed sensor in biological samples assay was also studied and imaged copper(II) ions in living pea aphids successfully. PMID:25640000

  20. Influence of different ruthenium(II) bipyridyl complex on the photocatalytic H 2 evolution over TiO 2 nanoparticles with mesostructures

    NASA Astrophysics Data System (ADS)

    Peng, Tianyou; Ke, Dingning; Cai, Ping; Dai, Ke; Ma, Liang; Zan, Ling

    H 2 production over dye-sensitized Pt/TiO 2 nanoparticles with mesostructures (m-TiO 2) under visible light (λ > 420 nm) was investigated by using methanol as electron donors. Experimental results indicate that three types of ruthenium(II) bipyridyl complex dyes (one binuclear Ru, two mononuclear Ru), which can be attached to Pt/ m-TiO 2 with different linkage modes, show different photosensitization effects due to their different coordination circumstances and physicochemical properties. The dye tightly linked with m-TiO 2 has better durability but the lowest H 2 evolution efficiency, whereas the loosely attached dyes possess higher H 2 evolution efficiency and preferable durability. It seems that the dynamic equilibrium between the linkage of the ground state dye with TiO 2 and the divorce of the oxidization state dye from the surfaces plays a crucial role in the photochemical behavior during the photocatalyst sensitization process. It is helpful to improve the H 2 evolution efficiency by enhancing the electron injection and hindering the backward transfer. The binuclear Ru(II) dye shows a better photosensitization in comparison with mononuclear Ru(II) dyes due to its large molecular area, conjugation system, and "antenna effect", which, in turn, improve the visible light harvesting and electron transfer between the dye molecules and TiO 2.

  1. A ruthenium(II) complex as turn-on Cu(II) luminescent sensor based on oxidative cyclization mechanism and its application in vivo

    NASA Astrophysics Data System (ADS)

    Zhang, Yunfei; Liu, Zonglun; Yang, Kui; Zhang, Yi; Xu, Yongqian; Li, Hongjuan; Wang, Chaoxia; Lu, Aiping; Sun, Shiguo

    2015-02-01

    Copper ions play a vital role in a variety of fundamental physiological processes not only in human beings and plants, but also for extensive insects and microorganisms. In this paper, a novel water-soluble ruthenium(II) complex as a turn-on copper(II) ions luminescent sensor based on o-(phenylazo)aniline was designed and synthesized. The azo group would undergo a specific oxidative cyclization reaction with copper(II) ions and turn into high luminescent benzotriazole, triggering significant luminescent increasements which were linear to the concentrations of copper(II) ions. The sensor distinguished by its high sensitivity (over 80-fold luminescent switch-on response), good selectivity (the changes of the emission intensity in the presence of other metal ions or amino acids were negligible) and low detection limit (4.42 nM) in water. Moreover, the copper(II) luminescent sensor exhibited good photostability under light irradiation. Furthermore, the applicability of the proposed sensor in biological samples assay was also studied and imaged copper(II) ions in living pea aphids successfully.

  2. In vitro evaluation of the cyto-genotoxic potential of Ruthenium(II) SCAR complexes: a promising class of antituberculosis agents.

    PubMed

    De Grandis, Rone Aparecido; Resende, Flávia Aparecida; da Silva, Monize Martins; Pavan, Fernando Rogério; Batista, Alzir Azevedo; Varanda, Eliana Aparecida

    2016-03-01

    Tuberculosis is a top infectious disease killer worldwide, caused by the bacteria Mycobacterium tuberculosis. Increasing incidences of multiple drug-resistance (MDR) strains are emerging as one of the major public health threats. However, the drugs in use are still incapable of controlling the appalling upsurge of MDR. In recent years a marked number of research groups have devoted their attention toward the development of specific and cost-effective antimicrobial agents against targeted MDR-Tuberculosis. In previous studies, ruthenium(II) complexes (SCAR) have shown a promising activity against MDR-Tuberculosis although few studies have indeed considered ruthenium toxicity. Therefore, within the preclinical requirements, we have sought to determine the cyto-genotoxicity of three SCAR complexes in this present study. The treatment with the SCARs induced a concentration-dependent decrease in cell viability in CHO-K1 and HepG2 cells. Based on the clonogenic survival, SCAR 5 was found to be more cytotoxic while SCAR 6 exhibited selectivity action on tumor cells. Although SCAR 4 and 5 did not indicate any mutagenic activity as evidenced by the Ames and Cytokinesis block micronucleus cytome assays, the complex SCAR 6 was found to engender a frameshift mutation detected by Salmonella typhimurium in the presence of S9. Similarly, we observed a chromosomal damage in HepG2 cells with significant increases of micronuclei and nucleoplasmic bridges. These data indicate that SCAR 4 and 5 complexes did not show genotoxicity in our models while SCAR 6 was considered mutagenic. This study presented a comprehensive genotoxic evaluation of SCAR complexes were shown to be genotoxic in vitro. All in all, further studies are required to fully elucidate how the properties can affect human health.

  3. Spectroscopic and quantum chemical investigation on non-covalent interaction in chromophore appended fullerene complexes of calix[4]arene

    NASA Astrophysics Data System (ADS)

    Halder, Amal; Bhattacharya, Sumanta

    2012-12-01

    The present paper describes the spectroscopic and theoretical insights on non-covalent interaction of a calix[4]arene molecule, namely, 4-iso-propyl-calix[4]arene (1) with chromophore appended fullerenes, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate (2) and [6,6]-phenyl-C71- butyric acid methyl ester (3) in solvents having varying polarity, viz., toluene and benzonitrile. Absorption spectrophotometric studies reveal appreciable ground state interaction between fullerenes and 1. The most fascinating feature of the present study is that 1 binds very effectively with both 2 and 3 as obtained from binding constant (K) data of such complexes; i.e., K2-1 and K3-1 exhibit value of 4.53 × 105 dm3 mol-1 (7.95 × 105 dm3 mol-1) and 13.35 × 105 dm3 mol-1 (27.62 × 105 dm3 mol-1) in toluene (benzonitrile), respectively. The effect of solvent over the complexation between fullerenes and 1 is clearly observed from the trend in the K values. Estimation of solvent reorganization energy (RS) evokes that both 2-1 and 3-1 complexes are stabilized more in toluene compared to benzonitrile. Molecular mechanics force field (MMMF) calculations in vacuo evoke geometrical structures of the 2-1 and 3-1 complexes and reveal interesting feature regarding binding pattern of fullerenes toward 1 in terms of heat of formation value of the respective complexes.

  4. Proparacaine complexation with beta-cyclodextrin and p-sulfonic acid calix[6]arene, as evaluated by varied (1)H-NMR approaches.

    PubMed

    Arantes, Lucas Micquéias; Scarelli, Camilla; Marsaioli, Anita Jocelyne; de Paula, Eneida; Fernandes, Sergio Antonio

    2009-09-01

    This study focused on the use of NMR techniques as a tool for the investigation of complex formation between proparacaine and cyclodextrins (CDs) or p-sulfonic acid calix[6]arene. The pH dependence of the complexation of proparacaine with beta-CD and p-sulfonic acid calix[6]arene was studied and binding constants were determined by (1)H NMR spectroscopy [diffusion-ordered spectroscopy (DOSY)] for the charged and uncharged forms of the local anesthetic in beta-CD and p-sulfonic acid calix[6]arene. The stoichiometries of the complexes was determined and rotating frame Overhauser enhancement spectroscopy (ROESY) 1D experiments revealed details of the molecular insertion of proparacaine into the beta-CD and p-sulfonic acid calix[6]arene cavities. The results unambiguously demonstrate that pH is an important factor for the development of supramolecular architectures based on beta-CD and p-sulfonic acid calix[6]arene as the host molecules. Such host-guest complexes were investigated in view of their potential use as new therapeutic formulations, designed to increase the bioavailability and/or to decrease the systemic toxicity of proparacaine in anesthesia procedures.

  5. Benzocaine complexation with p-sulfonic acid calix[n]arene: experimental ((1) H-NMR) and theoretical approaches.

    PubMed

    Arantes, Lucas M; Varejão, Eduardo V V; Pelizzaro-Rocha, Karin J; Cereda, Cíntia M S; de Paula, Eneida; Lourenço, Maicon P; Duarte, Hélio A; Fernandes, Sergio A

    2014-05-01

    The aim of this work was to study the interaction between the local anesthetic benzocaine and p-sulfonic acid calix[n]arenes using NMR and theoretical calculations and to assess the effects of complexation on cytotoxicity of benzocaine. The architectures of the complexes were proposed according to (1) H NMR data (Job plot, binding constants, and ROESY) indicating details on the insertion of benzocaine in the cavity of the calix[n]arenes. The proposed inclusion compounds were optimized using the PM3 semiempirical method, and the electronic plus nuclear repulsion energy contributions were performed at the DFT level using the PBE exchange/correlation functional and the 6-311G(d) basis set. The remarkable agreement between experimental and theoretical approaches adds support to their use in the structural characterization of the inclusion complexes. In vitro cytotoxic tests showed that complexation intensifies the intrinsic toxicity of benzocaine, possibly by increasing the water solubility of the anesthetic and favoring its partitioning inside of biomembranes.

  6. Calix[4]arene-based Zn2+ complexes as shape- and size-selective catalysts of ester cleavage.

    PubMed

    Cacciapaglia, Roberta; Casnati, Alessandro; Mandolini, Luigi; Reinhoudt, David N; Salvio, Riccardo; Sartori, Andrea; Ungaro, Rocco

    2005-07-01

    [structures: see text] The kinetics of methanolysis of a number of esters endowed with a carboxylate anchoring group have been investigated in the presence of di- and trinuclear Zn2+ complexes of calix[4]arenes functionalized at the upper rim with nitrogen ligands. The results (i) emphasize the importance of a good match between ester size and intermetal distance, (ii) reveal a substrate independent superiority of the 1,2-vicinal dinuclear catalyst 1-Zn2 to its 1,3-distal regioisomer 2-Zn2, and (iii) provide further evidence for the concurrence of the three metal ions of 3-Zn3 in the catalytic mechanism.

  7. Simultaneous determination of hydrazine and phenyl hydrazine using 4′-(4-carboxyphenyl)-2,2′:6′,2″ terpyridine diacetonitrile triphenylphosphine ruthenium(II) tetrafluoroborate complex functionalized multiwalled carbon nanotubes modified electrode

    SciTech Connect

    Tiwari, Ida; Gupta, Mandakini; Sinha, Preeti; Banks, Craig E.

    2014-12-15

    Highlights: • A nanocomposite of ruthenium(II) terpyridine, triphenylphosphine based complex and multiwalled carbon nanotubes have been used first time for simultaneous detection of hydrazine and phenyl hydrazine. • The detection limit reported is lower as compared to other reported works. • The paper also focuses towards effect of ligand variation attached to ruthenium(II) terpyridine based complexes complex for the hydrazine and phenyl hydrazine detection. • Nanocomposite does not involve any biological entity hence high stability. - Abstract: A nanocomposite based on the incorporation of the complex 4′-(4-carboxyphenyl)-2,2′:6′,2″ terpyridine triphenylphosphine diacetonitrile ruthenium(II) tetrafluoroborate with multiwalled carbon nanotubes and ionomer supported upon a glassy carbon electrode substrate is reported and characterized with scanning electron microscopy, transmission electron microscopy and infrared spectroscopy. The electrochemical behavior and stability of the composite electrode was investigated via cyclic voltammetry. The modified electrode exhibits an electro-catalytic activity towards the oxidation of both hydrazine and phenyl hydrazine in 0.1 M phosphate buffer solution (PBS, pH 7.4). The oxidation of hydrazine and phenyl hydrazine occurs at 0.81 V and 0.32 V with limit of detection found to be 3.7 × 10{sup −7} M and 1.15 × 10{sup −7} M and having a linear range from 5 × 10{sup −6} M to 6.5 × 10{sup −3} M, and 5 × 10{sup −6} M to 0.2 × 10{sup −3} M, respectively.

  8. Sensitization of nanocrystalline TiO2 anchored with pendant catechol functionality using a new tetracyanato ruthenium(II) polypyridyl complex.

    PubMed

    Kar, Prasenjit; Verma, Sandeep; Sen, Anik; Das, Amitava; Ganguly, Bishwajit; Ghosh, Hirendra Nath

    2010-05-01

    We have synthesized a new photoactive ruthenium(II) complex having a pendant catechol functionality (K(2)[Ru(CN)(4)(L)] (1) (L is 4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) for studying the dynamics of the interfacial electron transfer between nanoparticulate TiO(2) and the photoexcited states of this Ru(II) complex using femtosecond transient absorption spectroscopy. Steady-state absorption and emission studies revealed that the complex 1 showed a strong solvatochromic behavior in solvents or solvent mixtures of varying polarity. Our steady-state absorption studies further revealed that 1 is bound to TiO(2) surfaces through the catechol functionality, though 1 has two different types of functionalities (catecholate and cyanato) for binding to TiO(2) surfaces. The longer wavelength absorption band tail for 1, bound to TiO(2) through the proposed catecholate functionality, could also be explained on the basis of the DFT calculations. Dynamics of the interfacial electron transfer between 1 and TiO(2) nanoparticles was investigated by studying kinetics at various wavelengths in the visible and near-infrared region. Electron injection to the conduction band of the nanoparticulate TiO(2) was confirmed by detection of the conduction band electron in TiO(2) ([e(-)](TiO(2))(CB)) and cation radical of the adsorbed dye (1(*+)) in real time as monitored by transient absorption spectroscopy. A single exponential and pulse-width limited (<100 fs) electron injection was observed. Back electron transfer dynamics was determined by monitoring the decay kinetics of 1(*+) and [e(-)](TiO(2))(CB). This is the first report on ultrafast ET dynamics on TiO(2) nanoparticle surface using a solvatochromic sensitizer molecule.

  9. Ruthenium(II) carbonyl complexes bearing quinoline-based NNO tridentate ligands as catalyst for one-pot conversion of aldehydes to amides and o-allylation of phenols.

    PubMed

    Manikandan, R; Prakash, G; Kathirvel, R; Viswanathamurthi, P

    2013-12-01

    Six new octahedral ruthenium(II) carbonyl complexes having the general molecular formula [RuCl(CO)(B)L(1-2)] (B = PPh3, AsPh3 or py; L(1-2) = quinoline based NNO ligand) were synthesized. The quinoline based ligands behave as monoanionic tridentate donor and coordinated to ruthenium via ketoenolate oxygen, azomethine nitrogen and quinoline nitrogen. The composition of the complexes has been established by elemental analysis and spectral methods (FT-IR, electronic, (1)H NMR, (13)C NMR, (31)P NMR and ESI-Mass). The complexes were used as efficient catalysts for one-pot conversion of various aldehydes to their corresponding primary amides in presence of NH2OH · HCl and NaHCO3. The effect of catalyst loading and reaction temperature on catalytic activity of the ruthenium(II) carbonyl complexes were also investigated. The synthesized complexes also possess good catalytic activity for the o-allylation of phenols in the presence of K2CO3 under mild conditions. The complexes afforded branched allyl aryl ethers according to a regioselective reaction. PMID:23978737

  10. Ruthenium(II) carbonyl complexes bearing quinoline-based NNO tridentate ligands as catalyst for one-pot conversion of aldehydes to amides and o-allylation of phenols

    NASA Astrophysics Data System (ADS)

    Manikandan, R.; Prakash, G.; Kathirvel, R.; Viswanathamurthi, P.

    2013-12-01

    Six new octahedral ruthenium(II) carbonyl complexes having the general molecular formula [RuCl(CO)(B)L1-2] (B = PPh3, AsPh3 or py; L1-2 = quinoline based NNO ligand) were synthesized. The quinoline based ligands behave as monoanionic tridentate donor and coordinated to ruthenium via ketoenolate oxygen, azomethine nitrogen and quinoline nitrogen. The composition of the complexes has been established by elemental analysis and spectral methods (FT-IR, electronic, 1H NMR, 13C NMR, 31P NMR and ESI-Mass). The complexes were used as efficient catalysts for one-pot conversion of various aldehydes to their corresponding primary amides in presence of NH2OH·HCl and NaHCO3. The effect of catalyst loading and reaction temperature on catalytic activity of the ruthenium(II) carbonyl complexes were also investigated. The synthesized complexes also possess good catalytic activity for the o-allylation of phenols in the presence of K2CO3 under mild conditions. The complexes afforded branched allyl aryl ethers according to a regioselective reaction.

  11. Triflate-functionalized calix[6]arenes as versatile building-blocks: application to the synthesis of an inherently chiral Zn(ii) complex.

    PubMed

    Zahim, Sara; Lavendomme, Roy; Reinaud, Olivia; Luhmer, Michel; Evano, Gwilherm; Jabin, Ivan

    2016-02-14

    Cavity-based metal complexes can find many applications notably in the fields of catalysis and biomimicry. In this context, it was shown that metal complexes of calix[6]arenes bearing three aza-coordinating arms at the small rim provide excellent structural models of the poly-imidazole sites found in the active site of many metallo-enzymes. All these N-donor ligands were synthesized from the 1,3,5-tris-methoxy-p-tBu-calix[6]arene platform, which presents some limitations in terms of functionalization. Therefore, there is a need for the development of new calix[6]arene-based building-blocks selectively protected at the small rim. Herein we describe the regioselective one step synthesis of two calix[6]arenes decorated with triflate groups, i.e. X6H4Tf2 and X6H3Tf3, from the parent calix[6]arene X6H6. It is shown that the triflate groups can either act as protecting or deactivating groups, allowing the elaboration of sophisticated calixarene-based systems selectively functionalized at the large and/or at the small rim. In addition, X6H3Tf3 is functionalized on the A, B, and D rings and thus gives access to inherently chiral compounds, as demonstrated by the synthesis of a rare example of inherently chiral cavity-based metal complex.

  12. Triflate-functionalized calix[6]arenes as versatile building-blocks: application to the synthesis of an inherently chiral Zn(ii) complex.

    PubMed

    Zahim, Sara; Lavendomme, Roy; Reinaud, Olivia; Luhmer, Michel; Evano, Gwilherm; Jabin, Ivan

    2016-02-14

    Cavity-based metal complexes can find many applications notably in the fields of catalysis and biomimicry. In this context, it was shown that metal complexes of calix[6]arenes bearing three aza-coordinating arms at the small rim provide excellent structural models of the poly-imidazole sites found in the active site of many metallo-enzymes. All these N-donor ligands were synthesized from the 1,3,5-tris-methoxy-p-tBu-calix[6]arene platform, which presents some limitations in terms of functionalization. Therefore, there is a need for the development of new calix[6]arene-based building-blocks selectively protected at the small rim. Herein we describe the regioselective one step synthesis of two calix[6]arenes decorated with triflate groups, i.e. X6H4Tf2 and X6H3Tf3, from the parent calix[6]arene X6H6. It is shown that the triflate groups can either act as protecting or deactivating groups, allowing the elaboration of sophisticated calixarene-based systems selectively functionalized at the large and/or at the small rim. In addition, X6H3Tf3 is functionalized on the A, B, and D rings and thus gives access to inherently chiral compounds, as demonstrated by the synthesis of a rare example of inherently chiral cavity-based metal complex. PMID:26751614

  13. Solution NMR studies of supramolecular complexes of [60]- and [70]fullerenes with mono O-substituted calix[6]arene

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Sumanta; Chattopadhyay, Subrata; Nayak, Sandip K.; Banerjee, Manas

    2005-11-01

    Supramolecular complexation of [60]- and [70]fullerenes with 37-allyl-38,39,40,41,42-pentahydroxy-5,11,17,23,29,35-hexa(4- tert butyl)calix[6]arene ( I) has been studied in CCl 4 medium by NMR spectrometric method. All of the complexes are found to be stable with 1:1 stoichiometry. Formation constants ( K) of the above supramolecular complexes have been determined from systematic variation of NMR chemical shifts of specific protons of I in the presence of [60]- and [70]fullerenes. Trends in the K value suggest that [70]fullerene binds more strongly with I relative to [60]fullerene. Both PM3 and ab initio calculations reveal that the intermolecular interaction in the [70]fullerene/ I complex proceeds through quite deep energy minima.

  14. Dinuclear barium(II) complexes based on a calix[4]arene scaffold as catalysts of acyl transfer.

    PubMed

    Cacciapaglia, Roberta; Casnati, Alessandro; Di Stefano, Stefano; Mandolini, Luigi; Paolemili, Daniele; Reinhoudt, David N; Sartori, Andrea; Ungaro, Rocco

    2004-09-20

    Two novel regioisomeric calix[4]arene derivatives (2 and 3), decorated with two aza[18]crown-6 units at vicinal (1,2) or diagonal (1,3) positions of the upper rim, were synthesized. The catalytic activities of their dinuclear Ba2+ complexes were investigated in the ethanolysis of esters 8-11, endowed with a carboxylate anchoring group. Major results are as follows: 1) the two metal ions in the dinuclear catalysts work together in a cooperative fashion; 2) the vicinal calix[4]arene catalyst 2 is far superior to its diagonal regioisomer 3 in the reactions of all of the investigated esters; and 3) the distance between the carboxylate and ester carbonyl, which increases regularly from 8 to 11, influences reactivity of catalytic ester cleavage in a way that is decidedly suggestive of the importance of a good match between ester size and metal-to-metal distance. However, the superiority of the vicinal catalyst 2 relative to 3 cannot be explained on the basis of the putative match of ester size to intermetal distance, thus providing an indication that additional, still poorly understood effects may contribute significantly to catalytic efficiency.

  15. Spectroscopic and quantum chemical investigation on non-covalent interaction in chromophore appended fullerene complexes of calix[4]arene.

    PubMed

    Halder, Amal; Bhattacharya, Sumanta

    2012-12-01

    The present paper describes the spectroscopic and theoretical insights on non-covalent interaction of a calix[4]arene molecule, namely, 4-iso-propyl-calix[4]arene (1) with chromophore appended fullerenes, namely, tert-butyl-(1,2-methanofullerene)-61-carboxylate (2) and [6,6]-phenyl-C(71)- butyric acid methyl ester (3) in solvents having varying polarity, viz., toluene and benzonitrile. Absorption spectrophotometric studies reveal appreciable ground state interaction between fullerenes and 1. The most fascinating feature of the present study is that 1 binds very effectively with both 2 and 3 as obtained from binding constant (K) data of such complexes; i.e., K(2-1) and K(3-1) exhibit value of 4.53 × 10(5) dm(3) mol(-1) (7.95 × 10(5) dm(3) mol(-1)) and 13.35 × 10(5) dm(3) mol(-1) (27.62 × 10(5) dm(3) mol(-1)) in toluene (benzonitrile), respectively. The effect of solvent over the complexation between fullerenes and 1 is clearly observed from the trend in the K values. Estimation of solvent reorganization energy (R(S)) evokes that both 2-1 and 3-1 complexes are stabilized more in toluene compared to benzonitrile. Molecular mechanics force field (MMMF) calculations in vacuo evoke geometrical structures of the 2-1 and 3-1 complexes and reveal interesting feature regarding binding pattern of fullerenes toward 1 in terms of heat of formation value of the respective complexes.

  16. Catalysis of the carbonylation of olefins by the cationic chromium complexes allyl(arene)dicarbonylchromium(I) tetrafluoroborates

    SciTech Connect

    Magomedov, G.K.I.; Morozova, L.V.; Sigachev, S.A.; Krivykh, V.V.; Taits, E.S.; Rybinskaya, M.I.

    1986-11-10

    A qualitative comparison of the catalytic activities of the title complexes and cobalt carbonyl showed that (arene)allyldicarbonylchromium(I) tetrafluoroborates are more active than cobalt carbonyl, and this applies particularly to (C/sub 6/H/sub 6/Cr(CO)/sub 2/..pi..-C/sub 3/H/sub 5/)/sup +/BF/sub 4/. The possibility is not ruled out that in the course of the synthesis the acid HBF/sub 4/ is generated, and this is known to be a catalyst for the Koch reaction, but in this reaction only secondary and tertiary carboxy derivatives, i.e., only products of addition in accordance with the Markovnikov rule, are formed. In view of these results the authors investigated the activity of the title complexes in the hydroformylation process, an important industrial method for the preparation of aldehydes and alcohols.

  17. Inclusion complex formation of ternary system: Fluoroscein-p-sulfonato calix[4]arene-Cu(2+) by cooperative binding.

    PubMed

    Gawhale, Sharadchandra; Jadhav, Ankita; Rathod, Nilesh; Malkhede, Dipalee; Chaudhari, Gajanan

    2015-09-01

    The aqueous solution of fluorescein-para sulfonato calix[4]arene-metal ion complex has been studied based on absorption, fluorescence, (1)H NMR and FTIR spectroscopic results. It was found that the fluorescence intensity quenched regularly upon addition of pSCX4 and metal ion. The quenching constants and binding constants were determined for pSCX4-FL and pSCX4-FL-Cu(2+) systems. 1:1 stoichiometry is obtained for pSCX4-Cu(2+) system by continuous variation method. The NMR and IR results indicates the interaction among FL, pSCX4 and Cu(2+). The combined results demonstrate the cooperative binding to design the complex for ternary system. The life time for binary and ternary system has been studied.

  18. A triphenylamine-grafted imidazo[4,5-f][1,10]phenanthroline ruthenium(II) complex: acid-base and photoelectric properties.

    PubMed

    Fan, Su-Hua; Zhang, An-Guo; Ju, Chuan-Chuan; Gao, Li-Hua; Wang, Ke-Zhi

    2010-04-19

    A new heteroleptic ruthenium(II) complex of [Ru(Hipdpa)(Hdcbpy)(NCS)(2)](-).0.5H(+).0.5[N(C(4)H(9))(4)](+) Ru(Hipdpa) {where Hdcbpy = monodeprotonated 4,4'-dicarboxy-2,2'-bipyridine and Hipdpa = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline} was synthesized and characterized by elementary analysis, standard spectroscopy techniques, and cyclic voltammetry. The ground- and excited-state acid-base properties of Ru(Hipdpa) were studied by means of UV-vis absorption spectrophotometric and spectrofluorimetric titrations in 4:1(v/v) Britton-Robinson/dimethylformamide buffer solution. The four-step separate protonation/deprotonation processes were found in the ground states, and one of which taking place near the physiological pH range. The two observable excited-state protonation/deprotonation processes were found for the Ru(Hipdpa), constituting pH-induced "off-on-off" emission switches. The performance of the complexes as photosensitizers in nanocrystalline TiO(2)-based liquid solar cells containing an electrolyte solution (0.05 M I(2), 0.5 M LiI, and 0.5 M 4-tert-butylpyridine in 50% acetonitrile and 50% propylene carbonate) was investigated and found to achieve a much improved device performance (a short-circuit photocurrent density of 18.7 mA cm(-2), an open-circuit voltage of 630 mV, and an overall conversion efficiency of 6.85%) compared to a triphenylamine-free parent complex [Ru(Hpip)(Hdcbpy)(NCS)(2)](-).[N(C(4)H(9))(4)](+)-based device {Hpip = 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline} and a comparable performance to that of cis-bis(isothiocyanato)bis(2,2'-bipyridine-4,4'-dicarboxylic acid)ruthenium(II) (N3) under identical experimental conditions. A density functional theory calculation of the molecular structures and electronic properties of the complexes was also carried out in an effort to understand their effectiveness in TiO(2)-based solar cells.

  19. Multifunctional supramolecular vesicles based on the complex of ferrocenecarboxylic acid capped pillar[5]arene and a galactose derivative for targeted drug delivery.

    PubMed

    Chang, Yincheng; Hou, Chenxi; Ren, Jingli; Xin, Xiaoting; Pei, Yuxin; Lu, Yuchao; Cao, Shoupeng; Pei, Zhichao

    2016-07-21

    Supramolecular vesicles based on the host-guest complexation of ferrocenecarboxylic acid capped pillar[5]arene and a galactose derivative have been constructed, which showed dual-responsiveness and cancer cells targetability resulting from its ferrocenecarboxylic acid units and galactose units, respectively. This work provides a good example for the construction of multifunctional nanocarriers for targeted drug delivery. PMID:27387299

  20. Photoactivity of mono- and dicarbonyl complexes of ruthenium(II) bearing an N,N,S-donor ligand: role of ancillary ligands on the capacity of CO photorelease.

    PubMed

    Gonzalez, Margarita A; Carrington, Samantha J; Chakraborty, Indranil; Olmstead, Marilyn M; Mascharak, Pradip K

    2013-10-01

    One monocarbonyl and one dicarbonyl complex of ruthenium(II), namely, [Ru(Cl)(CO)(qmtpm)(PPh3)]BF4 (2) and [Ru(Cl)(CO)2(qmtpm)]ClO4 (3), derived from the tridentate ligand 2-quinoline-N-(2'-methylthiophenyl)methyleneimine (qmtpm) have been synthesized and structurally characterized. The qmtpm ligand binds in a meridional fashion in these carbonyl complexes, and in 3, the two carbon monoxide (CO) ligands are cis to each other. Solutions of 2 in ethanol, chloroform, or acetonitrile rapidly release CO upon illumination with low-power (3-15 mW) light in the 300-450 nm range. Loss of CO from 2 brings about a dramatic color change from yellow to magenta because of the formation of [Ru(Cl)(MeCN)(qmtpm)(PPh3)]BF4 (4). In acetonitrile, photorelease of CO from 3 under 360 nm light occurs in two steps, and the violet photoproduct [Ru(Cl)(MeCN)2(qmtpm)](+) upon reaction with Ag(+) and PPh3 affords red [Ru(MeCN)2(qmtpm)(PPh3)](ClO4)2 (5). The structure of 5 has also been determined by X-ray crystallography. Reduced myoglobin assay confirms that 2 and 3 act as photoactive CO-releasing molecules (photoCORMs) that deliver 1 and 2 equiv of CO, respectively. The results of density functional theory (DFT) and time-dependent DFT studies confirm that electronic transitions from molecular orbitals with predominantly Ru-CO character to ligand-based π* orbitals facilitate CO release from these two photoCORMs. Complexes 2-5 have provided an additional opportunity to analyze the roles of the ancillary ligands, namely, PPh3, Cl(-), and MeCN, in shifting the positions of the metal-to-ligand charge-transfer bands and the associated sensitivity of the two photoCORMs to different wavelengths of light. Collectively, the results provide helpful hints toward the future design of photoCORMs that release CO upon exposure to visible light.

  1. Complex behavior and source model of the tremor at Arenal volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Lesage, Philippe; Mora, Mauricio M.; Alvarado, Guillermo E.; Pacheco, Javier; Métaxian, Jean-Philippe

    2006-09-01

    Typical records of volcanic tremor and explosion quakes at Arenal volcano are analyzed with a high-resolution time-frequency method. The main characteristics of these seismic signals are: (1) numerous regularly spaced spectral peaks including both odd and even overtones; (2) frequency gliding in the range [0.9-2] Hz of the fundamental peak; (3) frequency jumps with either positive or negative increments; (4) tremor episodes with two simultaneous systems of spectral peaks affected by independent frequency gliding; (5) progressive transitions between spasmodic tremor and harmonic tremor; (6) lack of clear and systematic relationship between the occurrence of explosions and tremor. Some examples of alternation between two states of oscillation characterized by different fundamental frequencies are also observed. Some tremor and explosion codas are characterized by acoustic and seismic waves with identical spectral content and frequency gliding, which suggests a common excitation process. We propose a source model for the tremor at Arenal in which intermittent gas flow through fractures produces repetitive pressure pulses. The repeating period of the pulses is stabilized by a feedback mechanism associated with standing or traveling waves in the magmatic conduit. The pressure pulses generate acoustic waves in the atmosphere and act as excitation of the interface waves in the conduit. When the repeating period of the pulses is stable enough, they produce regularly spaced spectral peaks by the Dirac comb effect and hence harmonic tremor. When the period stability is lost, because of failures in the feedback mechanism, the tremor becomes spasmodic. The proposed source model of tremor is similar to the sound emission process of a clarinet. Fractures in the solid or viscous layer capping the lava pool in the crater act as the clarinet reed, and the conduit filled with low velocity bubbly magma is equivalent to the pipe of the musical instrument. The frequency gliding is

  2. Ruthenium(II) and osmium(II) 1,2,3-triazolylidene organometallics: a preliminary investigation into the biological activity of 'click' carbene complexes.

    PubMed

    Kilpin, Kelly J; Crot, Stéphanie; Riedel, Tina; Kitchen, Jonathan A; Dyson, Paul J

    2014-01-21

    Taking advantage of the facile and versatile synthetic properties of 'click' 1,2,3-triazolylidene N-heterocyclic carbenes (tzNHC's), a range of new organometallic Ru(II) and Os(II) arene complexes containing functionalised tzNHC ligands, [M(η(6)-p-cymene)(tzNHC)Cl2] [M = Ru(II), Os(II)], have been synthesised and fully characterised, including the X-ray crystal structure of one of the Os(II) complexes. The tzNHC ligands remain coordinated to the metal centres under relevant physiological conditions, and following binding to the model protein, ubiquitin. The in vitro cytotoxicity of the compounds towards human ovarian cancer cells is dependent on the substituent on the tzNHC ligand but is generally <50 μM and in some cases <1 μM, whilst still retaining a high degree of selectivity towards cancer cells over healthy cells (1.85 μM in A2780 ovarian cancer cells versus 435 μM in human embryonic kidney cells in one case).

  3. Visible-light-induced photooxidation of ruthenium(II) complex with 2,2'-biimidazole-like ligand by singlet oxygen.

    PubMed

    Li, Zheng-Zheng; Niu, Yan-Li; Zhou, Hai-Yun; Chao, Hsiu-Yi; Ye, Bao-Hui

    2013-09-01

    Four new ruthenium(II) complexes [Ru(bpy)2(TMBiimH2)](ClO4)2 (Ru-5; bpy is 2,2'-bipyridine and TMBiimH2 is 4,5,4',5'-tetramethyl-2,2'-biimidazole), [Ru(bpy)2(L1H2)](ClO4)2·H2O (Ru-6; L1H2 is 4,5-dimethyl-2-(N,N-diacetyl)carboximidamide-1H-imidazole), [Ru(bpy)2(L2H2)](ClO4)2 (Ru-7; L2H2 is N(1),N(1),N(2),N(2)-tetrakis(acetyl)ethanediimidamide), and [Ru(phen)2(TMBiimH2)](ClO4)2 (Ru-8; phen is 1,10'-phenanthroline) have been synthesized and characterized. Their photophysical and electrochemical properties have been studied and compared to the previously reported [Ru(bpy)2(BiimH2)](PF6)2 (Ru-1), [Ru(bpy)2(BbimH2)](PF6)2 (Ru-2), [Ru(bpy)2(DMBbimH2)](PF6)2 (Ru-3), and [Ru(bpy)2(TMBbimH2)](PF6)2 (Ru-4). Under irradiation with either sunlight or household light in atmosphere, Ru-5 reacts with molecular oxygen to produce Ru-6 in an acetonitrile solution with a relatively high concentration and Ru-7 in a methanol or dilute acetonitrile solution, respectively. The mechanism studies show that singlet oxygen is the reactive oxygen species in the ring-opening reaction and the photooxidation reaction is solvent- and concentration-dependent. The photoreaction product Ru-6 is an intermediate, which has been isolated and structurally characterized by single-crystal X-ray diffraction. Ru-6 is stable in the solid state and an acetonitrile solution with a high concentration, but can be further oxidized to Ru-7 in a methanol or dilute acetonitrile solution. PMID:23947382

  4. Syntheses and Characterization of Ruthenium(II) Tetrakis(pyridine)complexes: An Advanced Coordination Chemistry Experiment or Mini-Project

    ERIC Educational Resources Information Center

    Coe, Benjamin J.

    2004-01-01

    An experiment for third-year undergraduate a student is designed which provides synthetic experience and qualitative interpretation of the spectroscopic properties of the ruthenium complexes. It involves the syntheses and characterization of several coordination complexes of ruthenium, the element found directly beneath iron in the middle of the…

  5. Ruthenium-Arene-β-Carboline Complexes as Potent Inhibitors of Cyclin-Dependent Kinase 1: Synthesis, Characterization and Anticancer Mechanism Studies.

    PubMed

    He, Liang; Liao, Si-Yan; Tan, Cai-Ping; Ye, Rui-Rong; Xu, Yu-Wen; Zhao, Meng; Ji, Liang-Nian; Mao, Zong-Wan

    2013-09-01

    A series of Ru(II)-arene complexes (1-6) of the general formula [(η(6)-arene)Ru(L)Cl]PF6 (arene=benzene or p-cymene; L=bidentate β-carboline derivative, an indole alkaloid with potential cyclin-dependent kinases (CDKs) inhibitory activities) is reported. All the complexes were fully characterized by classical analytical methods, and three were characterized by X-ray crystallography. Hydrolytic studies show that β-carboline ligands play a vital role in their aqueous behaviour. These complexes are highly active in vitro, with the most active complex 6 displaying a 3- to 12-fold higher anticancer activity than cisplatin against several cancer cell lines. Interestingly, the complexes are able to overcome cross-resistance to cisplatin, and show much lower cytotoxicity against normal cells. Complexes 1-6 may directly target CDK1, because they can block cells in the G2M phase, down-regulate the expression of CDK1 and cyclin B1, and inhibit CDK1/cyclin B in vitro. Further mechanism studies show that the complexes can effectively induce apoptosis through mitochondrial-related pathways and intracellular reactive oxygen species (ROS) elevation.

  6. Mono and binuclear ruthenium(II) complexes containing 5-chlorothiophene-2-carboxylic acid ligands: Spectroscopic analysis and computational studies

    NASA Astrophysics Data System (ADS)

    Swarnalatha, Kalaiyar; Kamalesu, Subramaniam; Subramanian, Ramasamy

    2016-11-01

    New Ruthenium complexes I, II and III were synthesized using 5-chlorothiophene-2-carboxylic acid (5TPC), as ligand and the complexes were characterized by elemental analysis, FT-IR, 1H, 13C NMR, and mass spectroscopic techniques. Photophysical and electrochemical studies were carried out and the structures of the synthesized complex were optimized using density functional theory (DFT). The molecular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) energies and Mulliken atomic charges of the molecules are determined at the B3LYP method and standard 6-311++G (d,p) basis set starting from optimized geometry. They possess excellent stabilities and their thermal decomposition temperatures are 185 °C, 180 °C and 200 °C respectively, indicating that the metal complexes are suitable for the fabrication processes of optoelectronic devices.

  7. Cellular uptake, cytotoxicity, apoptosis, DNA-binding, photocleavage and molecular docking studies of ruthenium(II) polypyridyl complexes.

    PubMed

    Srishailam, A; Kumar, Yata Praveen; Venkat Reddy, P; Nambigari, Navaneetha; Vuruputuri, Uma; Singh, Surya S; Satyanarayana, S

    2014-03-01

    Three new mononuclear [Ru (phen)2 ptip](2+) (1), [Ru (bpy)2 ptip](2+) (2) and [Ru (dmb)2 ptip](2+) (3) [ptip=(2-(5-phenylthiophen-2-yl)-1H-imidazo[4, 5-f][1,10 phenanthroline, phen=1, 10 phenanthroline, bpy=2, 2' bipyridine, dmb=4, 4'-dimethyl 2, 2' bipyridine] complexes were synthesized and characterised by elemental analysis, IR, NMR and Mass spectra. The DNA-binding behaviours were investigated by electronic absorption titration, luminescence spectra, viscosity measurements and photo-activated cleavage. The DNA-binding constants Kb of complexes 1, 2 and 3 were determined to be 7.0 (± 0.06)× 10(5), 3.87 (± 0.04) × 10(5), 2.79 (±0.07) × 10(5) respectively. The results showed that these complexes interact with CT-DNA by intercalative mode. Cell viability experiments indicated that the Ru(II) complex showed significant dose-dependent cytotoxicity to HeLa tumour cell lines. Further flow cytometry experiments showed that the cytotoxic Ru(II) complex induced apoptosis of HeLa tumour cell lines. Our data demonstrated that the Ru(II) polypyridyl complex binds to DNA and thereby induces apoptosis in tumor cells, suggesting that anti-tumor activity of the Ru(II) complex could be related to its interaction with DNA. The molecular dynamic simulations and docking methods were used to predict the DNA binding affinity of ruthenium complexes and with good visualisation images supporting with experimental results.

  8. Optical spectroscopy studies of the complexation of bis(azophenol)calix[4]arene possessing chromogenic donors with Ni2+, Co2+, Cu2+, Pb2+ and Hg2+.

    PubMed

    Shaabani, Behrouz; Shaghaghi, Zohreh; Khandar, Ali Akbar

    2012-12-01

    Due to their potential applicability as selective receptors in electrochemical or optical sensors, a bis(azophenol)calix[4]arene derivative H(2)L has been investigated. The complexation properties of this molecule towards Ni(2+) and Co(2+) metal ions has been studied. It is revealed that this ligand exhibits tetradentate with N(2)O(2) core when bound to Ni (II) or Co (II) metal ion. The optical response of azo groups of H(2)L towards Ni(2+), Co(2+), Cu(2+), Pb(2+) and Hg(2+) metal ions has been investigated in DMSO by UV-vis spectroscopy. The absorption spectra of calix[4]arene with cations show marked changes, especially for Co(2+) ion. Furthermore, Job's plot indicate 1:1 binding-stiochiometry for calix[4]arene with Co(2+) ion and Benson-Hilderbrand plot is used for the determination of its association constant. The investigation of UV-vis spectra of chromogenic calix[4]arene in different solvents shows that cis-trans isomerization of azo groups probably depends on kind of solvent. Also the different between the polarity and viscosity of organic solvents used is likely responsible for the changes of the band shape of the spectra.

  9. Spectroscopic and theoretical investigations on effective and selective complexation between fullerenes (C 60 and C 70) and calix[5]arene

    NASA Astrophysics Data System (ADS)

    Halder, Amal; Goswami, Dibakar; Nayak, Sandip K.; Chattopadhyay, Subrata; Bhattacharya, Sumanta

    2009-11-01

    Ground state interactions between a macrocyclic calixarene receptor, namely, 4- tert-butyl calix[5]arene ( 1) with fullerenes C 60 and C 70, were studied by absorption spectrophotometric method in toluene medium. Well defined charge transfer (CT) absorption bands were located for the complexes of C 60 and C 70 with 1. Utilizing the CT absorption bands, various important physico-chemical parameters like oscillator strength, resonance energy and electronic coupling elements were determined for fullerene- 1 complexes. It was observed that 1 binds preferentially C 70 compared to C 60 as obtained from binding constant ( K) data, i.e., K-1= 23600 dm 3 mol -1 and K-1= 94460 dm 3 mol -1. Proton NMR investigations also provided a very good support in favor of strong complexation between C 70 and 1. PM3 calculations established that binding pattern of C 70 towards 1 was end-on rather than side-on as C 70/ 1 complex gained 2.43 kJ mol -1 of extra stabilization energy in case of its end-on orientation rather than traditional side-on approach.

  10. Synthesis, structure, and C-H bond activation chemistry of ([eta][sup 6]-arene)Ru(H)[sub 2](SiMe[sub 3])[sub 2] complexes

    SciTech Connect

    Djurovich, P.I.; Carroll, P.J.; Berry, D.H. )

    1994-07-01

    The ([eta][sup 6]-arene)Ru(H)[sub 2](SiMe[sub 3])[sub 2] arene = C[sub 6]-Me[sub 6] (1a), p-cymene (1b), C[sub 6]H[sub 6] (1c) complexes have been prepared and characterized. The complexes activate both aromatic and aliphatic C-H bonds and catalyze H/D exchange in alkylsilanes upon thermolysis in benzene-d[sub 6]. A mechanism based on oxidative-addition/reductive-elimination steps which utilizes a Ru(II)-Ru(IV) cycle is proposed to account for the C-H bond activation and H/D exchange reactions. It is further proposed that H/D exchange into sites adjacent to silicon in alkylsilanes is due to the intermediacy of an [eta][sup 2]-silene complex generated by [beta]-hydrogen elimination from the silyl group. 19 refs., 1 fig.

  11. Teaching Inorganic Photophysics and Photochemistry with Three Ruthenium(II) Polypyridyl Complexes: A Computer-Based Exercise

    ERIC Educational Resources Information Center

    Garino, Claudio; Terenzi, Alessio; Barone, Giampaolo; Salassa, Luca

    2016-01-01

    Among computational methods, DFT (density functional theory) and TD-DFT (time-dependent DFT) are widely used in research to describe, "inter alia," the optical properties of transition metal complexes. Inorganic/physical chemistry courses for undergraduate students treat such methods, but quite often only from the theoretical point of…

  12. Facile η5-η3 hapticity interconversion in pentamethylcyclopentadienyl ruthenium(II) complexes containing a phenylmethallyl ("open indenyl") ligand.

    PubMed

    Glöckner, Andreas; Àrias, Òscar; Bannenberg, Thomas; Daniliuc, Constantin G; Jones, Peter G; Tamm, Matthias

    2011-11-21

    The indenyl effect has been introduced to pentadienyl ("open cyclopentadienyl") chemistry by preparation of the phenylmethallyl ("open indenyl") ligand oInd(Me). The reaction of its potassium salt K(oInd(Me)) with [(η(5)-C(5)Me(5))RuCl](4) afforded the sandwich complex [(η(5)-C(5)Me(5))Ru(η(5)-oInd(Me))] (1), which, upon treatment with PMe(3), CO, and 2,6-dimethylphenyl isocyanide (CN-o-Xy), easily underwent η(5)-η(3) hapticity interconversion and formed the complexes [(η(5)-C(5)Me(5))Ru(η(3)-oInd(Me))(L)] (2, L = PMe(3); 3, L = CO; 4, L = CN-o-Xy). In these complexes, the η(3)-bound phenylmethallyl ligand adopts an anti-conformation with regard to the relative positions of the phenyl and methyl substituents. For the PMe(3) complex anti-2, slow conversion to the syn-isomer was observed, and this equilibrium reaction was monitored by NMR spectroscopy at 50 °C to determine a first order rate constant of k(323 K) = 6.57 × 10(-6) (± 0.02 × 10(-6)) s(-1) and an activation barrier of ΔG° = 26.8 kcal mol(-1). DFT calculations afforded a stabilization of syn-2 and syn-3 by ΔG(298) = -1.54 and -1.74 kcal mol(-1) over the respective anti-isomer.

  13. Photoinduced singlet charge transfer in a ruthenium(II) perylene-3,4:9,10-bis(dicarboximide) complex.

    PubMed

    Gunderson, Victoria L; Krieg, Elisha; Vagnini, Michael T; Iron, Mark A; Rybtchinski, Boris; Wasielewski, Michael R

    2011-06-16

    Elucidation of photoinduced charge transfer behavior in organic dye/metal hybrids is important for developing photocatalytic systems for solar energy conversion. We report the synthesis and photophysical characterization of a perylene-3,4:9,10-bis(dicarboximide) (PDI)-ruthenium(II) complex, bis-PDI-2,2'-bipyridineRu(II)Cl(2)(CN(t)butyl)(2), which has favorable energetics, ΔG(CS) ≈ -1.0 eV, for singlet electron transfer from the Ru complex to PDI. Time-resolved optical spectroscopy reveals that upon selective photoexcitation of PDI, ultrafast charge transfer (<150 fs) from the Ru complex to (1*)PDI generates the Ru(III)-PDI(-•) ion pair. The resulting vibrationally hot Ru(III)-PDI(-•) ion pair exhibits fast relaxation (τ = 3.9 ps) and charge recombination (τ(CR) = 63 ps). Our experimental and computational (DFT and TDDFT) studies show that energy-preserving photodriven singlet electron transfer can dominate in properly designed organic dye/metal complexes, making them of particular interest for use in artificial photosynthetic systems for solar fuels formation. PMID:21598951

  14. Langmuir-Blodgett films of a clay mineral and ruthenium(II) complexes with a noncentrosymmetric structure.

    PubMed

    Umemura, Yasushi; Yamagishi, Akihiko; Schoonheydt, Robert; Persoons, André; De Schryver, Frans

    2002-02-13

    Mono- and multilayers of amphiphilic [Ru(phen)(2)(dcC12bpy)](2+) (phen = 1,10-phenanthroline, dcC12bpy = 4,4'-caboxyl-2,2'-bipyridyl didodecyl ester) hybridized with a clay mineral have been prepared by a modified Langmuir-Blodgett method, and their structures and properties have been investigated. Formation of a hybrid monolayer of the Ru(II) complex cations and the clay platelets at an air-clay suspension interface was confirmed by surface pressure-molecular area (pi-A) isotherm measurement and atomic force microscopic (AFM) observation. Multilayers were fabricated by depositing the hybrid monolayers onto glass substrates. The absorbance at 492 nm due to the Ru(II) complex cation in the multilayer increased linearly with the increase in the layer number, indicating layer-by-layer deposition of the hybrid monolayers. Because no increase in the second-harmonic generation (SHG) signal from the multilayers against the layer number was observed, the orientation of the Ru(II) complex cations in the layer would be disturbed. The hydrophilic surface of the transferred hybrid monolayer can be converted to a hydrophobic surface by dipping it in an aqueous solution of octadecylammonium chloride (ODAH(+)Cl(-)). The multilayers modified with ODAH(+) showed a quadratic relation between the SHG intensity and the layer number. This means that the Ru(II) complex cations in the multilayer are successfully oriented in a noncentrosymmetric way by the conversion of the surface property. Both a racemic mixture and an enantiomer of the Ru(II) complex cations were employed to examine the chiral effect on the film properties. The chiral contribution to the SHG signal was enhanced in the multilayer modified with ODAH(+).

  15. Ruthenium(II) bipyridine complexes bearing new keto-enol azoimine ligands: Synthesis, structure, electrochemistry and DFT calculations

    NASA Astrophysics Data System (ADS)

    Al-Noaimi, Mousa; Awwadi, Firas F.; Mansi, Ahmad; Abdel-Rahman, Obadah S.; Hammoudeh, Ayman; Warad, Ismail

    2015-01-01

    The novel azoimine ligand, Phsbnd NHsbnd Ndbnd C(COCH3)sbnd NHPh(Ctbnd CH) (H2L), was synthesized and its molecular structure was determined by X-ray crystallography. Catalytic hydration of the terminal acetylene of H2L in the presence of RuCl3·3H2O in ethanol at reflux temperature yielded a ketone (L1 = Phsbnd Ndbnd Nsbnd C(COCH3)dbnd Nsbnd Ph(COCH3) and an enol (L2 = Phsbnd Ndbnd Nsbnd C(COCH3)dbnd Nsbnd PhC(OH)dbnd CH2) by Markovnikov addition of water. Two mixed-ligand ruthenium complexes having general formula, trans-[Ru(bpy)(Y)Cl2] (1-2) (where Y = L1 (1) and Y = L2 (2), bpy is 2.2‧-bipyrdine) were achieved by the stepwise addition of equimolar amounts of (H2L) and bpy ligands to RuCl3·3H2O in absolute ethanol. Theses complexes were characterized by elemental analyses and spectroscopic (IR, UV-Vis, and NMR (1D 1H NMR, 13C NMR, (DEPT-135), (DEPT-90), 2D 1H-1H and 13C-1H correlation (HMQC) spectroscopy)). The two complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 604 mV vs. ferrocene/ferrocenium (Cp2Fe0/+) couple along with one electron ligand reduction at -1010 mV. The crystal structure of complex 1 showed that the bidentate ligand L1 coordinates to Ru(II) by the azo- and imine-nitrogen donor atoms. The complex adopts a distorted trans octahedral coordination geometry of chloride ligands. The electronic spectra of 1 and 1+ in dichloromethane have been modeled by time-dependent density functional theory (TD-DFT).

  16. Ruthenium(II) bipyridine complexes bearing new keto-enol azoimine ligands: synthesis, structure, electrochemistry and DFT calculations.

    PubMed

    Al-Noaimi, Mousa; Awwadi, Firas F; Mansi, Ahmad; Abdel-Rahman, Obadah S; Hammoudeh, Ayman; Warad, Ismail

    2015-01-25

    The novel azoimine ligand, Ph-NH-N=C(COCH3)-NHPh(C≡CH) (H2L), was synthesized and its molecular structure was determined by X-ray crystallography. Catalytic hydration of the terminal acetylene of H2L in the presence of RuCl3·3H2O in ethanol at reflux temperature yielded a ketone (L1=Ph-N=N-C(COCH3)=N-Ph(COCH3) and an enol (L2=Ph-N=N-C(COCH3)=N-PhC(OH)=CH2) by Markovnikov addition of water. Two mixed-ligand ruthenium complexes having general formula, trans-[Ru(bpy)(Y)Cl2] (1-2) (where Y=L1 (1) and Y=L2 (2), bpy is 2.2'-bipyrdine) were achieved by the stepwise addition of equimolar amounts of (H2L) and bpy ligands to RuCl3·3H2O in absolute ethanol. Theses complexes were characterized by elemental analyses and spectroscopic (IR, UV-Vis, and NMR (1D (1)H NMR, (13)C NMR, (DEPT-135), (DEPT-90), 2D (1)H-(1)H and (13)C-(1)H correlation (HMQC) spectroscopy)). The two complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 604 mV vs. ferrocene/ferrocenium (Cp2Fe(0/+)) couple along with one electron ligand reduction at -1010 mV. The crystal structure of complex 1 showed that the bidentate ligand L1 coordinates to Ru(II) by the azo- and imine-nitrogen donor atoms. The complex adopts a distorted trans octahedral coordination geometry of chloride ligands. The electronic spectra of 1 and 1+ in dichloromethane have been modeled by time-dependent density functional theory (TD-DFT).

  17. A new arene-Ru based supramolecular coordination complex for efficient binding and selective sensing of green fluorescent protein.

    PubMed

    Mishra, Anurag; Ravikumar, Sambandam; Song, Young Ho; Prabhu, Nadarajan Saravanan; Kim, Hyunuk; Hong, Soon Ho; Cheon, Seyeon; Noh, Jaegeun; Chi, Ki-Whan

    2014-04-28

    A new dipyridyl ligand is encoded with 120° angularity between its coordination vectors by using a central pyridine carboxamide scaffold to orient two 4-(pyridin-4-ylethynyl)phenyl moieties. The N,N'-bis(4-(pyridin-4-ylethynyl)phenyl)pyridine-2,6-dicarboxamide ligand undergoes self-assembly with a diruthenium arene complex to furnish a [2 + 2] metallacycle with a wedge-like structure. The metallacycle binds to the enhanced green fluorescent protein (EGFP) variant of GFP, resulting in steady-state spectral changes in UV-Vis absorption and emission experiments. These studies indicate that the metallacycle induces conformation changes to the EGFP, disrupting the tripeptide chromophore. Furthermore, gel electrophoresis, circular dichroism and atomic force microscopy studies indicate that binding ultimately leads to aggregation of the protein. Computational investigations indicate a favorable interaction, predominantly between the metallacycle and the Arg168 residue of the EGFP. An interaction with Arg168 and related residues was previously observed for an emission-attenuating antibody, supporting that these interactions induce changes to the photophysical properties of EGFP by disrupting the tripeptidechromophore in a similar manner. Additionally, we have also described the quenching study of the reporter GFP protein in vivo by a new metal complex using reflected fluorescence microscopy. We anticipate that such metal complexes which can passively diffuse into the cells in vivo can serve as potential tools in molecular and drug targeting based biological studies.

  18. Development of more labile low electron count Co(I) sources: mild, catalytic functionalization of activated alkanes using a [(Cp*Co)2-μ-(η4:η4-arene)] complex.

    PubMed

    Hung-Low, Fernando; Krogman, Jeremy P; Tye, Jesse W; Bradley, Christopher A

    2012-01-11

    Catalytic transfer dehydrogenation of silyl protected amines, requiring sp(3) C-H bond activation, is mediated by a bridging arene complex of the type [(Cp*Co)(2)-μ-(η(4):η(4)-arene)] under mild conditions. Mechanistic and qualitative rate studies establish the compound as a more reactive Co(I) source when compared to other known Cp*Co(I) complexes. PMID:22083519

  19. Ab initio and DFT studies on vibrational spectra of some mixed carbonyl-halide complexes of ruthenium(II)

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Zhao, Jianying; Tang, Guodong; Zhu, Longgen

    2005-02-01

    The vibrational spectra of Ru(CO) 62+ and some of its mixed carbonyl-halide complexes, cis-Ru(CO) 2X 42-, fac-Ru(CO) 3X 3- and Ru(CO) 5X + (X = F, Cl, Br and I), have been systematically investigated by ab initio RHF and density functional B3LYP methods with LanL2DZ and SDD basis sets. The calculated vibrational frequencies of complexes Ru(CO) 62+, cis-Ru(CO) 2X 42- and fac-Ru(CO) 3X 3- are evaluated via comparison with the experimental values. In the infrared frequency region, the C-O stretching vibrational frequencies calculated at B3LYP level with two basis sets are in good agreement with the observed values with deviations less than 5%. In the far-infrared region, the B3LYP/SDD method achieved the best results with deviations less than 8% for Ru-X stretching and less than 2% for Ru-C stretching vibrational frequencies. The vibrational frequencies for Ru(CO) 5X + that have not been experimentally reported were predicted.

  20. Structural studies on dinuclear ruthenium(II) complexes that bind diastereoselectively to an antiparallel folded human telomere sequence.

    PubMed

    Wilson, Tom; Costa, Paulo J; Félix, Vítor; Williamson, Mike P; Thomas, Jim A

    2013-11-14

    We report DNA binding studies of the dinuclear ruthenium ligand [{Ru(phen)2}2tpphz](4+) in enantiomerically pure forms. As expected from previous studies of related complexes, both isomers bind with similar affinity to B-DNA and have enhanced luminescence. However, when tested against the G-quadruplex from human telomeres (which we show to form an antiparallel basket structure with a diagonal loop across one end), the ΛΛ isomer binds approximately 40 times more tightly than the ΔΔ, with a stronger luminescence. NMR studies show that the complex binds at both ends of the quadruplex. Modeling studies, based on experimentally derived restraints obtained for the closely related [{Ru(bipy)2}2tpphz](4+), show that the ΛΛ isomer fits neatly under the diagonal loop, whereas the ΔΔ isomer is unable to bind here and binds at the lateral loop end. Molecular dynamics simulations show that the ΔΔ isomer is prevented from binding under the diagonal loop by the rigidity of the loop. We thus present a novel enantioselective binding substrate for antiparallel basket G-quadruplexes, with features that make it a useful tool for quadruplex studies.

  1. Synthesis of novel p-tert-butylcalix[4]arene Schiff bases and their complexes with C60, potential HIV-Protease inhibitors

    NASA Astrophysics Data System (ADS)

    Khadra, Khalid Abu; Mizyed, Shehadeh; Marji, Deeb; Haddad, Salim F.; Ashram, Muhammad; Foudeh, Ayat

    2015-02-01

    Some p-tert-butylcalix[4]arene Schiff base crown ethers were synthesized, characterized using 1H, 13C-NMR, DEPT 135 and Mass spectrometry. Their complexes with C60 were isolated and characterized. The inhibition effect of these complexes on HIVP was studied and found that complexes of 9 and 10 have comparable Ki values to Pepstatine which is known as HIVP inhibitor and used as a control. The synthesis of the ligands, complexes and the inhibition behavior are discussed in this article.

  2. Crystal structures of resorcin[4]arene and pyrogallol[4]arene complexes with DL-pipecolinic acid. Model compounds for the recognition of the pipecolinyl ring, a key fragment of FK506, through C-H⋯π interaction

    NASA Astrophysics Data System (ADS)

    Fujisawa, Ikuhide; Kitamura, Yuji; Kato, Ryo; Murayama, Kazutaka; Aoki, Katsuyuki

    2014-01-01

    Resorcin[4]arene (resorcinol cyclic tetramer, abbreviated as RCT) or pyrogallol[4]arene (pyrogallol cyclic tetramer, PCT) form host-guest 1:1 complexes with DL-pipecolinic acid (DL-pipeH), RCT·DL-pipeH·EtOH·8H2O (1), PCT DL-pipeH·EtOH·4H2O (2), and PCT·DL-pipeH·3H2O (3), whose crystal structures have been determined. In each complex, the pipeH ligand is incorporated into the bowl-shaped cavity of the RCT or PCT host molecules through C-H⋯π interactions between alkyl protons of the piperidine ring of pipeH and π-rings of RCT or PCT, forming an [(RCT/PCT)·pipeH] structural fragment. In 1 and 3, two [(RCT/PCT) pipeH] fragments self-associate across an inversion center to form a guest-mediated, obliquely declined dimeric structure [(RCT/PCT)·L-pipeH·D-pipeH (RCT/PCT)]. In 2, each PCT-capped pipeH ligand bridges to two adjacent PCT molecules to form guest-mediated, optically-discrete helical polymers [PCT·L-pipeH]n or [PCT·D-pipeH]n. An 1H NMR experiment shows that the complexation through C-H⋯π interaction between the piperidine ring of pipeH and π-rings of RCT or PCT occurs also in solution, with the binding constants of 9.7 ± 0.6 M-1 for RCT and 26.5 ± 1.5 M-1 for PCT. These complexes provide a synthetic model for the recognition of the pipecolinyl-ring moiety, a key constituent of immunosuppressant drugs such as FK506, FK520 or rapamycin, by their binding proteins through C-H⋯π interaction.

  3. Alkali metal cation complexation by 1,3-alternate, mono-ionisable calix[4]arene-benzocrown-6 compounds

    DOE PAGESBeta

    Surowiec, Malgorzata A.; Custelcean, Radu; Surowiec, Kazimierz; Bartsch, Richard A.

    2014-04-23

    Alkali metal cation extraction behavior for two series of 1,3-alternate, mono-ionizable calix[4]arene-benzocrown-6 compounds is examined. In Series 1, the proton-ionizable group is a substituent on the benzo group of the polyether ring that directs it away from the crown ether cavity. In Series 2, the proton-ionizable group is attached to one para position in the calixarene framework, thus positioning it over the crown ether ring. Competitive solvent extraction of alkali metal cations from aqueous solutions into chloroform shows high Cs+ efficiency and selectivity. Single-species extraction pH profiles of Cs+ for Series 1 and 2 ligands with the same proton-ionizable groupmore » are very similar. Thus, association of Cs+ with the calixcrown ring is more important than the the proton-ionizable group’s position in relation to the crown ether cavity. Solid-state structures are presented for two unionized ligands from Series 2, as is a crystal containing two different ionized ligand–Cs+ complexes.« less

  4. Alkali metal cation complexation by 1,3-alternate, mono-ionisable calix[4]arene-benzocrown-6 compounds

    SciTech Connect

    Surowiec, Malgorzata A.; Custelcean, Radu; Surowiec, Kazimierz; Bartsch, Richard A.

    2014-04-23

    Alkali metal cation extraction behavior for two series of 1,3-alternate, mono-ionizable calix[4]arene-benzocrown-6 compounds is examined. In Series 1, the proton-ionizable group is a substituent on the benzo group of the polyether ring that directs it away from the crown ether cavity. In Series 2, the proton-ionizable group is attached to one para position in the calixarene framework, thus positioning it over the crown ether ring. Competitive solvent extraction of alkali metal cations from aqueous solutions into chloroform shows high Cs+ efficiency and selectivity. Single-species extraction pH profiles of Cs+ for Series 1 and 2 ligands with the same proton-ionizable group are very similar. Thus, association of Cs+ with the calixcrown ring is more important than the the proton-ionizable group’s position in relation to the crown ether cavity. Solid-state structures are presented for two unionized ligands from Series 2, as is a crystal containing two different ionized ligand–Cs+ complexes.

  5. DNA-binding, topoisomerases I and II inhibition and in vitro cytotoxicity of ruthenium(II) polypyridyl complexes: [Ru(dppz)2L]2+ (L = dppz-11-CO2Me and dppz)

    NASA Astrophysics Data System (ADS)

    He, Xiaojun; Jin, Lianhe; Tan, Lifeng

    2015-01-01

    Two ruthenium(II) polypyridyl complexes, [Ru(dppz)2dppz-11-CO2Me](ClO4)2 (Ru1) and [Ru(dppz)3](ClO4)2 (Ru2), have been synthesized and characterized. The spectral characteristics of Ru1 and Ru2 were investigated by fluorescence spectroscopy and revealed that both complexes were sensitive to solvent polarity. The binding properties of the two complexes towards calf-thymus DNA (CT-DNA) have been investigated by different spectrophotometric methods and viscosity measurements, indicating that both complexes bind to CT-DNA by means of intercalation, but with different binding affinities. Topoisomerase inhibition and DNA strand passage assay demonstrates that the two complexes are dual inhibitors of topoisomerases I and IIa. On the other hand, the cytotoxicity of both complexes has been evaluated by MTT assays and Giemsa staining experiments. The main results reveal that the ester functional group has a significant effect on the DNA-binding affinities and topoisomerases inhibition effects of Ru1 and Ru2, and further advance our knowledge on the DNA-binding and topoisomerase inhibition by Ru(II) complexes.

  6. Dynamic NMR studies of restricted arene rotation in the chromiu tricarbonyl thiophene and selenophene complexes

    SciTech Connect

    Sanger, M.J.

    1994-05-27

    This thesis contains the results of organometallic studies of thiophene and selenophene coordination in transition metal complexes. Chromium tricarbonyl complexes of thiophene, selenophene, and their alkyl-substituted derivatives were prepared and variable-temperature {sup 13}C NMR spectra of these complexes were recorded in dimethyl ether. Bandshape analyses of these spectra yielded activation parameters for restricted rotation of the thiophene and selenophene ligands in these complexes. Extended Hueckel molecular orbital calculations (EHMO) of the free thiophene and selenophene ligands and selected chromium tricarbonyl thiophene complexes were performed to better explain the activation barriers of these complexes. The structure of Cr(CO){sub 3}({eta}{sup 5}-2,5-dimethylthiophene) was established by a single crystal X-ray diffraction study.

  7. Rare-earth metal π-complexes of reduced arenes, alkenes, and alkynes: bonding, electronic structure, and comparison with actinides and other electropositive metals.

    PubMed

    Huang, Wenliang; Diaconescu, Paula L

    2015-09-21

    Rare-earth metal complexes of reduced π ligands are reviewed with an emphasis on their electronic structure and bonding interactions. This perspective discusses reduced carbocyclic and acyclic π ligands; in certain categories, when no example of a rare-earth metal complex is available, a closely related actinide analogue is discussed. In general, rare-earth metals have a lower tendency to form covalent interactions with π ligands compared to actinides, mainly uranium. Despite predominant ionic interactions in rare-earth chemistry, covalent bonds can be formed with reduced carbocyclic ligands, especially multiply reduced arenes.

  8. Because Trucks Aren't Bicycles: Orthographic Complexity as an Important Variable in Reading Research

    ERIC Educational Resources Information Center

    Galletly, Susan A.; Knight, Bruce Allen

    2013-01-01

    Severe enduring reading- and writing-accuracy difficulties seem a phenomenon largely restricted to nations using complex orthographies, notably Anglophone nations, given English's highly complex orthography (Geva and Siegel, "Read Writ" 12:1-30, 2000; Landerl et al., "Cognition" 63:315-334, 1997; Share, "Psychol Bul"l 134(4):584-615, 2008;…

  9. Asymmetric synthesis of axially chiral benzamides and anilides by enantiotopic lithiation of prochiral arene chromium complexes.

    PubMed

    Koide, Hiroshige; Hata, Takeshi; Uemura, Motokazu

    2002-03-22

    Axially chiral benzamides and anilides were prepared by enantiotopic lithiation at the distinguished benzylic methyl of prochiral tricarbonylchromium complexes of N,N-diethyl 2,6-dimethylbenzamide (1) and N-methyl-N-acyl 2,6-dimethylaniline (14 and 21) with a chiral lithium amide base followed by electrophilic substitution in good yields with high optical purity. The resulting axially chiral chromium-complexed benzamides and anilides were oxidized under air to give chromium-free axially chiral benzamides and anilides in an enantiomerically active form without axial bond rotation at room temperature. PMID:11895413

  10. Supramolecular modeling of mono-copper enzyme active sites with calix[6]arene-based funnel complexes.

    PubMed

    Le Poul, Nicolas; Le Mest, Yves; Jabin, Ivan; Reinaud, Olivia

    2015-07-21

    Supramolecular bioinorganic chemistry is a natural evolution in biomimetic metallic systems since it constitutes a further degree of complexity in modeling. The traditional approach consisting of mimicking the first coordination sphere of metal sites proved to be very efficient, because valuable data are extracted from these examples to gain insight in natural systems mechanisms. But it does not reproduce several specific aspects of enzymes that can be mimicked by the implementation of a cavity embedding the labile active site and thus controlling the properties of the metal ion by noncovalent interactions. This Account reports on a strategy aimed at reproducing some supramolecular aspects encountered in the natural systems. The cavity complexes described herein display a coordination site constructed on a macrocycle. Thanks to a careful design of the cavity-based ligands, complexes orienting their labile site specifically toward the inside of the macrocycle were obtained. The supramolecular systems are based on the flexible calix[6]arene core that surrounds the metal ion labile site, thereby constraining exogenous molecules to pass through the conic funnel to reach the metal center. Such an architecture confers to the metal ion very unusual properties and behaviors, which in many aspects are biologically relevant. Three generations of calix[6]-based ligands are presented and discussed in the context of modeling the monocopper sites encountered in some enzymes. A wide range of phenomena are highlighted such as the impact that the size and shape of the access channel to the metal center have on the selectivity and rate of the binding process, the possible remote control of the electronics through small modifications operated on the cavity edges, induced-fit behavior associated with host-guest association (shoe-tree effect) that affects the redox properties of the metal ion and the electron exchange pathway, consequences of forbidden associative ligand exchange

  11. Determination of the Regiochemistry of Disubstituted Arenes Generated by Addition of a Carbanion to the (h6-Anisole)Cr(CO)3 Complex

    NASA Astrophysics Data System (ADS)

    Bengali, Ashfaq A.; Samet, Cindy; Charlton, Samantha B.

    2001-01-01

    It has become increasingly important to demonstrate to undergraduates that chemistry is not many separate subfields, but rather a set of interconnected concepts. We describe a laboratory activity that integrates fundamental concepts of organic and organometallic chemistry and then employs standard instrumental techniques (GC) and molecular modeling to justify the results. Students synthesize the (h6-anisole)Cr(CO)3 complex and react it with the -:CH2CN anion to generate methoxyphenylacetonitrile. They then determine the relative amounts of the three possible regioisomers of the disubstituted arene using GC. We have shown this synthesis to be straightforward for students to accomplish, with results that are reproducible.

  12. Coordination chemistry of a calix[4]arene-based NHC ligand: dinuclear complexes and comparison to I(i)Pr2Me2.

    PubMed

    Patchett, Ruth; Chaplin, Adrian B

    2016-06-01

    The preparation and coordination chemistry of 5,17-bis(3-methyl-1-imidazol-2-ylidene)-25,26,27,28-tetrapropoxycalix[4]arene (1) is described. Starting from the bis(imidazolium) pro-ligand 1·2HI, the free carbene 1 was readily generated in solution through deprotonation using K[O(t)Bu] and its reactivity with rhodium(i) dimers [Rh(COD)Cl]2 (COD = 1,5-cyclooctadiene) and [Rh(CO)2Cl]2 investigated. Dinuclear complexes were isolated in both cases, where the calix[4]arene-based NHC ligand adopts a bridging μ(2)-coordination mode, and in one case characterised in the solid-state by X-ray diffraction. Using instead an isolated and well-defined (mononuclear) silver transfer agent, generated by reaction of 1·2HI with Ag2O in the presence of a halide extractor, reactions with [Rh(COD)Cl]2 and [Rh(CO)2Cl]2 produced cationic dinuclear complexes bearing μ(2)-1 and μ(2)-Cl bridging ligands. The structural formulation of the novel dinuclear adducts of 1 was aided through spectroscopic congruence with model complexes, containing monodentate 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (I(i)Pr2Me2).

  13. Host-guest chemistry of a water-soluble pillar[5]arene: evidence for an ionic-exchange recognition process and different complexation modes.

    PubMed

    Gómez, Borja; Francisco, Vitor; Fernández-Nieto, Fernando; Garcia-Rio, Luis; Martín-Pastor, M; Paleo, M Rita; Sardina, F Javier

    2014-09-15

    The complexation of an anionic guest by a cationic water-soluble pillararene is reported. Isothermal titration calorimetry (ITC), (1)H NMR, (1)H and (19)F DOSY, and STD NMR experiments were performed to characterize the complex formed under aqueous neutral conditions. The results of ITC and (1)H NMR analyses showed the inclusion of the guest inside the cavity of the pillar[5]arene, with the binding constant and thermodynamic parameters influenced by the counter ion of the macrocycle. NMR diffusion experiments showed that although a fraction of the counter ions are expelled from the host cavity by exchange with the guest, a complex with both counter ions and the guest inside the pillararene is formed. The results also showed that at higher concentrations of guest in solution, in addition to the inclusion of one guest molecule in the cavity, the pillararene can also form an external complex with a second guest molecule.

  14. Functionalized arene-ruthenium(II) complexes: dangling vs. tethering side chain.

    PubMed

    Lastra-Barreira, Beatriz; Díez, Josefina; Crochet, Pascale; Fernández, Israel

    2013-04-21

    The reactivity of compounds [RuCl2(η(6)-C6H5OCH2CH2OH)(L)] (L = phosphine or phosphite) towards the chloride abstractor AgSbF6 has been investigated. Thus, the treatment of the triphenylphosphite complex [RuCl2(η(6)-C6H5OCH2CH2OH){P(OPh)3}] with one equivalent of AgSbF6 gave rise to the formation of the dinuclear dichloro-bridged species [{Ru(μ-Cl)(η(6)-C6H5OCH2CH2OH){P(OPh)3}}2](2+) as the hexafluoroantimonate salt. On the other hand, the triphenylphosphine analog [RuCl2(η(6)-C6H5OCH2CH2OH)(PPh3)] led, under the same experimental conditions, to the di-ruthenium derivative [{RuCl(η(6)-C6H5OCH2CH2OH)(PPh3)}2(μ-Cl)][SbF6] containing only one Cl-bridge. In sharp contrast, treatment of precursors [RuCl2(η(6)-C6H5CH2CH2CH2OH)(L)] (L = P(OPh)3, PPh3, P(OEt)3) with AgSbF6 resulted in the clean formation of the tethered compounds [RuCl{η(6):κ(1)(O)-C6H5CH2CH2CH2OH}(L)][SbF6]. The differences in reactivity observed have been rationalized by theoretical calculations.

  15. A novel dual-functioning ruthenium(II)-arene complex of an anti-microbial ciprofloxacin derivative - Anti-proliferative and anti-microbial activity.

    PubMed

    Ude, Ziga; Romero-Canelón, Isolda; Twamley, Brendan; Fitzgerald Hughes, Deirdre; Sadler, Peter J; Marmion, Celine J

    2016-07-01

    7-(4-(Decanoyl)piperazin-1-yl)-ciprofloxacin, CipA, (1) which is an analogue of the antibiotic ciprofloxacin, and its ruthenium(II) complex [Ru(η(6)-p-cymene)(CipA-H)Cl], (2) have been synthesised and the x-ray crystal structures of 1·1.3H2O·0.6CH3OH and 2·CH3OH·0.5H2O determined. The complex adopts a typical pseudo-octahedral 'piano-stool' geometry, with Ru(II) π-bonded to the p-cymene ring and σ-bonded to a chloride and two oxygen atoms of the chelated fluoroquinolone ligand. The complex is highly cytotoxic in the low μM range and is as potent as the clinical drug cisplatin against the human cancer cell lines A2780, A549, HCT116, and PC3. It is also highly cytotoxic against cisplatin- and oxaliplatin-resistant cell lines suggesting a different mechanism of action. The complex also retained low μM cytotoxicity against the human colon cancer cell line HCT116p53 in which the tumour suppressor p53 had been knocked out, suggesting that the potent anti-proliferative properties associated with this complex are independent of the status of p53 (in contrast to cisplatin). The complex also retained moderate anti-bacterial activity in two Escherichia coli, a laboratory strain and a clinical isolate resistant to first, second and third generation β-lactam antibiotics.

  16. Selectivity of calix[4]arene-bis(benzocrown-6) in the complexation and transport of francium ion.

    PubMed

    Haverlock, Tamara J; Mirzadeh, Saed; Moyer, Bruce A

    2003-02-01

    It is shown for the first time that a representative member of the "cesium-selective" calix[4]arene-crown-6 family exhibits a high affinity for Fr+ ion. In the investigation, the transport of 221Fr+ and Cs+ ions by calix[4]arene-bis(benzocrown-6) from an aqueous sodium nitrate solution into the water-immiscible diluent 1,2-dichloroethane was measured and compared to address the question of selectivity of the calix-crown-6 cavity toward alkali metal ions of increasing size. Selective separation of 221Fr+ from its parent 225Ac and from the matrix Na+ ions was demonstrated. Higher distribution ratios were obtained than those for the Cs+ ion. The extraction equilibria were determined for the case of the Cs+ ion, and the same equilibria were shown to be applicable to the case of Fr+ with inclusion of additional competitive effects. PMID:12553788

  17. BODIPY-modified Ru(II) arene complex--a new ligand dissociation mechanism and a novel strategy to red shift the photoactivation wavelength of anticancer metallodrugs.

    PubMed

    Zhou, Qian-Xiong; Lei, Wan-Hua; Hou, Yuan-Jun; Chen, Yong-Jie; Li, Chao; Zhang, Bao-Wen; Wang, Xue-Song

    2013-02-28

    A Ru(II) arene complex [(η(6)-p-cymene)Ru(bpy)(py-BODIPY)](PF(6))(2), where bpy is 2,2'-bipyridine and py-BODIPY is a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene dye containing a pyridine group at the 8-position, was designed and synthesized. BODIPY modification renders the monodentate pyridine ligand with long wavelength absorbing capability, and an absorption maximum at 504 nm. Upon selective irradiation of the absorption band of the py-BODIPY ligand, the dissociation of the monodentate ligand occurs efficiently, followed by substitution by 9-ethylguanine if it is present in the solution. The photoinduced ligand dissociation quantum yield was measured to be 4.1% at 480 nm. The photoinduced electron transfer from the BODIPY chromophore to the Ru(II) arene moiety plays an important role in the ligand dissociation. Such a photosensitization strategy can be utilized to develop novel anticancer metallodrugs that may respond to light in the phototherapeutic window (650-900 nm).

  18. Comparison of hydration reactions for "piano-stool" RAPTA-B and [Ru(η6-arene)(en)Cl]+ complexes: density functional theory computational study.

    PubMed

    Chval, Zdeněk; Futera, Zdeněk; Burda, Jaroslav V

    2011-01-14

    The hydration process for two Ru(II) representative half-sandwich complexes: Ru(arene)(pta)Cl(2) (from the RAPTA family) and [Ru(arene)(en)Cl](+) (further labeled as Ru_en) were compared with analogous reaction of cisplatin. In the study, quantum chemical methods were employed. All the complexes were optimized at the B3LYP/6-31G(d) level using Conductor Polarizable Continuum Model (CPCM) solvent continuum model and single-point (SP) energy calculations and determination of electronic properties were performed at the B3LYP∕6-311++G(2df,2pd)/CPCM level. It was found that the hydration model works fairly well for the replacement of the first chloride by water where an acceptable agreement for both Gibbs free energies and rate constants was obtained. However, in the second hydration step worse agreement of the experimental and calculated values was achieved. In agreement with experimental values, the rate constants for the first step can be ordered as RAPTA-B > Ru_en > cisplatin. The rate constants correlate well with binding energies (BEs) of the Pt∕Ru-Cl bond in the reactant complexes. Substitution reactions on Ru_en and cisplatin complexes proceed only via pseudoassociative (associative interchange) mechanism. On the other hand in the case of RAPTA there is also possible a competitive dissociation mechanism with metastable pentacoordinated intermediate. The first hydration step is slightly endothermic for all three complexes by 3-5 kcal∕mol. Estimated BEs confirm that the benzene ligand is relatively weakly bonded assuming the fact that it occupies three coordination positions of the Ru(II) cation. PMID:21241133

  19. Comparison of hydration reactions for "piano-stool" RAPTA-B and [Ru(η6- arene)(en)Cl]+ complexes: Density functional theory computational study

    NASA Astrophysics Data System (ADS)

    Chval, Zdeněk; Futera, Zdeněk; Burda, Jaroslav V.

    2011-01-01

    The hydration process for two Ru(II) representative half-sandwich complexes: Ru(arene)(pta)Cl2 (from the RAPTA family) and [Ru(arene)(en)Cl]+ (further labeled as Ru_en) were compared with analogous reaction of cisplatin. In the study, quantum chemical methods were employed. All the complexes were optimized at the B3LYP/6-31G(d) level using Conductor Polarizable Continuum Model (CPCM) solvent continuum model and single-point (SP) energy calculations and determination of electronic properties were performed at the B3LYP/6-311++G(2df,2pd)/CPCM level. It was found that the hydration model works fairly well for the replacement of the first chloride by water where an acceptable agreement for both Gibbs free energies and rate constants was obtained. However, in the second hydration step worse agreement of the experimental and calculated values was achieved. In agreement with experimental values, the rate constants for the first step can be ordered as RAPTA-B > Ru_en > cisplatin. The rate constants correlate well with binding energies (BEs) of the Pt/Ru-Cl bond in the reactant complexes. Substitution reactions on Ru_en and cisplatin complexes proceed only via pseudoassociative (associative interchange) mechanism. On the other hand in the case of RAPTA there is also possible a competitive dissociation mechanism with metastable pentacoordinated intermediate. The first hydration step is slightly endothermic for all three complexes by 3-5 kcal/mol. Estimated BEs confirm that the benzene ligand is relatively weakly bonded assuming the fact that it occupies three coordination positions of the Ru(II) cation.

  20. Synthesis and reactivity of ((eta/sup 5/-C/sub 5/R/sub 5/)Ru(eta/sup 6/-arene))PF/sub 6/ (R = H, CH/sub 3/) complexes of naphthalene, anthracene, pyrene, chrysene, and azulene. Kinetic studies of arene displacement reactions in acetonitrile solutions

    SciTech Connect

    McNair, A.M.; Mann, K.R.

    1986-07-16

    The synthesis and characterization of new ((eta/sup 5/-C/sub 5/H/sub 5/)Ru(eta/sup 6/-arene))PF/sub 6/ and ((eta/sup 5/-C/sub 5/(CH/sub 3/)/sub 5/)Ru(eta/sup 6/-arene))PF/sub 6/ complexes are reported (arene = naphthalene, anthracene, pyrene, chrysene, azulene). Kinetic studies of arene displacement by acetonitrile for five of these complexes are reported. The values obtained for k/sub obsd/ range from 1.3 x 10/sup -2/ s/sup -1/ to 4.6 x 10/sup -6/ s/sup -1/ in 2.73 M CH/sub 3/CN. The differences between the rates observed for the C/sub 5/H/sub 5//sup -/ complexes and the C/sub 5/(CH/sub 3/)/sub 5//sup -/ compound are explained in terms of an associative mechanism. Rate constants for the ruthenium compounds containing pyrene and chrysene were found to be approximately 4 orders of magnitude larger, respectively, than those for the corresponding Fe complexes. This is believed to be an effect of the difference in the sizes of the two metals and their subsequent susceptibility toward nucleophilic attack. The temperature and concentration dependence of the rate constant k was studied for the reaction of (eta/sup 5/-C/sub 5/(CH/sub 3/)/sub 5/)Ru(eta/sub 6/-anthracene))/sup +/ with CH/sub 3/CN. The ..delta..S double dagger of -13.3 (9) eu and ..delta..H double dagger = +14.9 (3) kcal/mol confirm the associative nature of the displacement reaction. The straight-line plot obtained for k/sub obsd/ vs. (CH/sub 3/CN) is consistent with a rate equation of the general form rate = k(M)(CH/sub 3/CH) where (M) is the concentration of the metal complex. Two mechanisms consistent with the data are proposed and discussed; on includes a preequilibrium between a eta/sup 6/-arene metal complex and a eta/sup 4/-arene species, while the other involves direct nucleophilic attack on the metal-center of the eta/sup 6/ complex.

  1. Tris(triazolyl) calix[6]arene-based zinc and copper funnel complexes: imidazole-like or pyridine-like? A comparative study.

    PubMed

    Colasson, Benoit; Le Poul, Nicolas; Le Mest, Yves; Reinaud, Olivia

    2011-11-01

    Huisgen dipolar cycloaddition leads straightforwardly to new funnel complexes based on the calix[6]arene macrocycle bearing three functionalized triazoles as coordinating units at the small rim. Coordination to Zn(II) and Cu(I) cations was studied using (1)H NMR and IR spectroscopies and cyclic voltammetry. The nature of the substituents on the triazole ring affects the behavior of the ligands and their coordinating ability and controls the host-guest properties of the metal receptors for exogenous substrates. Depending on their substitution pattern but also on the metal ion and the guest ligand, the triazole-based systems behave either imidazole-like or pyridine-like. The ease of preparation and the versatility of 1,4-disubstituted-1,2,3-triazoles with tunable steric and electronic properties make them promising candidates for further applications from biology to materials.

  2. Water-Soluble Ruthenium(II) Complexes with Chiral 4-(2,3-Dihydroxypropyl)-formamide Oxoaporphine (FOA): In Vitro and in Vivo Anticancer Activity by Stabilization of G-Quadruplex DNA, Inhibition of Telomerase Activity, and Induction of Tumor Cell Apoptosis.

    PubMed

    Chen, Zhen-Feng; Qin, Qi-Pin; Qin, Jiao-Lan; Zhou, Jie; Li, Yu-Lan; Li, Nan; Liu, Yan-Cheng; Liang, Hong

    2015-06-11

    Three water-soluble ruthenium(II) complexes with chiral 4-(2,3-dihydroxypropyl)-formamide oxoaporphine (FOA) were synthesized and characterized. It was found that these ruthenium(II) complexes exhibited considerable in vitro anticancer activities and that they were the effective stabilizers of telomeric and G-quadruplex-DNA (G4-DNA) in promoter of c-myc, which acted as a telomerase inhibitor targeting G4-DNA and induced cell senescence and apoptosis. Interestingly, the in vitro anticancer activity of 6 (LC-003) was higher than those of 4 (LC-001) and 5 (LC-002), more selective for BEL-7404 cells than for normal HL-7702 cells, and preferred to activate caspases-3/9. The different biological behaviors of the ruthenium complexes could be correlated with the chiral nature of 4-(2,3-dihydroxypropyl)-formamide oxoaporphine. More significantly, 6 exhibited effective inhibitory on tumor growth in BEL-7402 xenograft mouse model and higher in vivo safety than cisplatin. These mechanistic insights indicate that 6 displays low toxicity and can be a novel anticancer drug candidate.

  3. η(6) -Arene-Zirconium-PNP-Pincer Complexes: Mechanism of Their Hydrogenolytic Formation and Their Reactivity as Zirconium(II) Synthons.

    PubMed

    Plundrich, Gudrun T; Wadepohl, Hubert; Clot, Eric; Gade, Lutz H

    2016-06-27

    The cyclometalated monobenzyl complexes [(Cbzdiphos(R) -CH)ZrBnX] 1 (iPr) Cl and 1 (Ph) I reacted with dihydrogen (10 bar) to yield the η(6) -toluene complexes [(Cbzdiphos(R) )Zr(η(6) -tol)X] 2 (iPr) Cl and 2 (Ph) I (cbzdiphos=1,8-bis(phosphino)-3,6-di-tert-butyl-9H-carbazole). The arene complexes were also found to be directly accessible from the triiodide [(Cbzdiphos(Ph) )ZrI3 ] through an in situ reaction with a dibenzylmagnesium reagent and subsequent hydrogenolysis, as exemplified for the η(6) -mesitylene complex [(Cbzdiphos(Ph) )Zr(η(6) -mes)I] (3 (Ph) I). The tolyl-ring in 2 (iPr) Cl adopts a puckered arrangement (fold angle 23.3°) indicating significant arene-1,4-diido character. Deuterium labeling experiments were consistent with an intramolecular reaction sequence after the initial hydrogenolysis of a Zr-C bond by a σ-bond metathesis. A DFT study of the reaction sequence indicates that hydrogenolysis by σ-bond metathesis first occurs at the cyclometalated ancillary ligand giving a hydrido-benzyl intermediate, which subsequently reductively eliminates toluene that then coordinates to the Zr atom as the reduced arene ligand. Complex 2 (Ph) I was reacted with 2,6-diisopropylphenyl isocyanide giving the deep blue, diamagnetic Zr(II) -diisocyanide complex [(Cbzdiphos(Ph) )Zr(CNDipp)2 I] (4 (Ph) I). DFT modeling of 4 (Ph) I demonstrated that the HOMO of the complex is primarily located as a "lone pair on zirconium", with some degree of back-bonding into the C≡N π* bond, and the complex is thus most appropriately described as a zirconium(II) species. Reaction of 2 (Ph) I with trimethylsilylazide (N3 TMS) and 2 (iPr) Cl with 1-azidoadamantane (N3 Ad) resulted in the formation of the imido complexes [(Cbzdiphos(R) )Zr=NR'(X)] 5 (iPr) Cl-NAd and 5 (Ph) I-NTMS, respectively. Reaction of 2 (iPr) Cl with azobenzene led to N-N bond scission giving 6 (iPr) Cl, in which one of the NPh-fragments is coupled with the carbazole

  4. η(6) -Arene-Zirconium-PNP-Pincer Complexes: Mechanism of Their Hydrogenolytic Formation and Their Reactivity as Zirconium(II) Synthons.

    PubMed

    Plundrich, Gudrun T; Wadepohl, Hubert; Clot, Eric; Gade, Lutz H

    2016-06-27

    The cyclometalated monobenzyl complexes [(Cbzdiphos(R) -CH)ZrBnX] 1 (iPr) Cl and 1 (Ph) I reacted with dihydrogen (10 bar) to yield the η(6) -toluene complexes [(Cbzdiphos(R) )Zr(η(6) -tol)X] 2 (iPr) Cl and 2 (Ph) I (cbzdiphos=1,8-bis(phosphino)-3,6-di-tert-butyl-9H-carbazole). The arene complexes were also found to be directly accessible from the triiodide [(Cbzdiphos(Ph) )ZrI3 ] through an in situ reaction with a dibenzylmagnesium reagent and subsequent hydrogenolysis, as exemplified for the η(6) -mesitylene complex [(Cbzdiphos(Ph) )Zr(η(6) -mes)I] (3 (Ph) I). The tolyl-ring in 2 (iPr) Cl adopts a puckered arrangement (fold angle 23.3°) indicating significant arene-1,4-diido character. Deuterium labeling experiments were consistent with an intramolecular reaction sequence after the initial hydrogenolysis of a Zr-C bond by a σ-bond metathesis. A DFT study of the reaction sequence indicates that hydrogenolysis by σ-bond metathesis first occurs at the cyclometalated ancillary ligand giving a hydrido-benzyl intermediate, which subsequently reductively eliminates toluene that then coordinates to the Zr atom as the reduced arene ligand. Complex 2 (Ph) I was reacted with 2,6-diisopropylphenyl isocyanide giving the deep blue, diamagnetic Zr(II) -diisocyanide complex [(Cbzdiphos(Ph) )Zr(CNDipp)2 I] (4 (Ph) I). DFT modeling of 4 (Ph) I demonstrated that the HOMO of the complex is primarily located as a "lone pair on zirconium", with some degree of back-bonding into the C≡N π* bond, and the complex is thus most appropriately described as a zirconium(II) species. Reaction of 2 (Ph) I with trimethylsilylazide (N3 TMS) and 2 (iPr) Cl with 1-azidoadamantane (N3 Ad) resulted in the formation of the imido complexes [(Cbzdiphos(R) )Zr=NR'(X)] 5 (iPr) Cl-NAd and 5 (Ph) I-NTMS, respectively. Reaction of 2 (iPr) Cl with azobenzene led to N-N bond scission giving 6 (iPr) Cl, in which one of the NPh-fragments is coupled with the carbazole

  5. Heterobimetallic bismuth(III)/molybdenum(VI) and antimony(III)/molybdenum(VI) calix[5]arene complexes. Progress toward modeling the SOHIO catalyst.

    PubMed

    Mendoza-Espinosa, Daniel; Hanna, Tracy A

    2009-08-01

    The treatment of the monometallic bismuth or antimony complexes [M{(t)BuC5(H)(2)}] (M = Bi, Sb) with 1.5 equiv of MoO(2)(O(t)Bu)(2) in 1,2-dimethoxyethane (DME) produced soluble Bi(III)/Mo(VI) and Sb(III)/Mo(VI) heterometallic calix[5]arene complexes [Bi(2)Mo(4)O(11){(t)BuC5(H)}(2)] 1 and [Sb(2)Mo(4)O(11){(t)BuC5(H)}(2)] 2 in 55 and 45% yields, respectively. In solution the (1)H NMR patterns for 1 and 2 are characteristic of a C(s) symmetry with three pairs of doublets for the methylene protons and three singlets in a 1:2:2 ratio for the tert-butyl groups. Complex 1 crystallizes in the P1 space group and consists of a dimeric heterometallic Bi/Mo (1:2 ratio) complex featuring an overall Mo(4)Bi(2)O(21) oxo cluster. The remarkable oxo-rich core structure of 1 contains Bi(mu-O)Mo, Mo(mu-O)Mo, Mo=O...Mo, and Bi-O-Bi interactions that resemble aspects of the proposed SOHIO catalyst active site and the crystal structure of the Bi(2)Mo(2)O(9) oxide phase. PMID:19552450

  6. Methods for preparation of cyclopentadienyliron (II) arenes

    DOEpatents

    Keipert, Steven J.

    1991-01-01

    Two improved methods for preparation of compounds with the structure shown in equation X [(Cp)--Fe--(Ar)].sup.+.sub.b X.sup.b- (X) where Cp is an eta.sup.5 complexed, substituted or unsubstituted, cyclopentadienyl or indenyl anion, Ar is an eta.sup.6 complexed substituted or unsubstituted, pi-arene ligand anad X is a b-valent anion where b is an integer between 1 and 3. The two methods, which differ in the source of the cyclopentadienyl anion - Lewis acid complex, utilize a Lewis acid assisted ligand transfer reaction. The cyclopentadienyl anion ligand, assisted by a Lewis acid is transferred to ferrous ion in the presence of an arene. In the first method, the cyclopentadienyl anion is derived from ferrocene and ferrous chloride. In this reaction, the cyclopentadienyliron (II) arene product is derived partially from ferrocene and partially from the ferrous salt. In the second method, the cyclopentadienyl anion - Lewis acid complex is formed by direct reaction of the Lewis acid with an inorganic cyclopentadienide salt. The cyclopentadienyliron (II) arene product of this reaction is derived entirely from the ferrous salt. Cyclopentadienyliron (II) arene cations are of great interest due to their utility as photoactivatable catalysts for a variety of polymerization reactions.

  7. Diglycolamide-functionalized calix[4]arenes showing unusual complexation of actinide ions in room temperature ionic liquids: role of ligand structure, radiolytic stability, emission spectroscopy, and thermodynamic studies.

    PubMed

    Mohapatra, Prasanta K; Sengupta, Arijit; Iqbal, Mudassir; Huskens, Jurriaan; Verboom, Willem

    2013-03-01

    Diglycolamide-functionalized calix[4]arenes (C4DGAs) with varying structural modifications were evaluated for actinide complexation from their extraction behavior toward actinide ions such as UO2(2+), Pu(4+), PuO2(2+), and Am(3+) in the room temperature ionic liquid (RTIL) 1-n-octyl-3-methylimidazolium bis(trifluoromethane)sulfonamide (C8mimNTf2). The formation constants were calculated for Am(3+) which showed a significant role of ligand structure, nature of substituents, and spacer length. Although the alkyl substituents on the amidic nitrogen increase the extraction efficiency of americium at lower acidity because of the inductive effect of the alkyl groups, at higher acidity the steric crowding around the ligating site determines the extraction efficiency. All C4DGAs formed 1:1 complexes with Am(3+) while for the analogous Eu(3+) complexes no inner sphere water molecules were detected and the asymmetry of the metal ligand complex differed from one another as proved by time-resolved laser induced fluorescence spectroscopy (TRLIFS). Thermodynamic studies indicated that the extraction process, predominant by the Am(3+)-C4DGA complexation reaction, is exothermic. The unique role of the medium on Am(3+) complexation with the C4DGA molecules with varying spacer length, L-IV and L-V, was noticed for the first time with a reversal in the trend observed in the RTIL compared to that seen in a nonpolar molecular diluent like n-dodecane. Various factors leading to a more preorganized structure were responsible for favorable metal ion complexation. The solvent systems show promise to be employed for nuclear waste remediation, and sustainability options were evaluated from radiolytic stability as well as stripping studies.

  8. Novel chiral (salen)Mn(III) complexes containing a calix[4]arene unit in 1,3-alternate conformation as catalysts for enantioselective epoxidation reactions of (Z)-aryl alkenes.

    PubMed

    Bonaccorso, Carmela; Brancatelli, Giovanna; Ballistreri, Francesco P; Geremia, Silvano; Pappalardo, Andrea; Tomaselli, Gaetano A; Toscano, Rosa M; Sciotto, Domenico

    2014-02-01

    Two new chiral calix[4]arene-salen ligands 1a,b, based on calix[4]arene platforms in 1,3-alternate conformation, have been prepared by a new general synthetic pathway. Their Mn(III) complexes, 3a,b have shown fairly good efficiency in the asymmetric epoxidation of styrene and substituted styrenes, whereas excellent catalytic activity and selectivity were observed with rigid bicyclic alkenes, namely 1,2-dihydro-naphthalene and substituted 2,2'-dimethyl-chromene. The higher catalytic properties of 3a may be ascribed to the more rigid and inherently chiral structure as proved by molecular modelling, NMR spectroscopy and X-ray data of the similarly structured UO2 complexes 2a,b.

  9. Ruthenium(II) and osmium(II) complexes bearing bipyridine and the N-heterocyclic carbene-based C^N^C pincer ligand: an experimental and density functional theory study.

    PubMed

    Chung, Lai-Hon; Cho, Ka-Sin; England, Jason; Chan, Siu-Chung; Wieghardt, Karl; Wong, Chun-Yuen

    2013-09-01

    Ruthenium(II) and osmium(II) complexes [M(C^N^C)(N^N)L](n+) (L = Cl(-), n = 1; L = CH3CN, t-BuNC, n = 2) containing a neutral tridentate N-heterocyclic carbene (NHC)-based pincer ligand, either 2,6-bis(1-butylimidazol-2-ylidene)pyridine (C(1)^N^C(1)) or 2,6-bis(3-butylbenzimidazol-2-ylidene)pyridine (C(2)^N^C(2)), and a neutral 2,2'-bipyridine-type aromatic diimine have been prepared. Investigations into the effects of varying M (Ru and Os), C^N^C, N^N, and L on the structural, electrochemical, absorption, and emission characteristics associated with [M(C^N^C)(N^N)L](n+) are presented. Interestingly, spectroscopic findings and time-dependent density functional theory (TD-DFT) calculations in this work support a dπ(Ru(II)/Os(II)) → π*(N^N) metal-to-ligand charge transfer (MLCT) assignment for the lowest-energy transition in [M(C^N^C)(N^N)L](n+) and not a dπ(Ru(II)/Os(II)) → π*(C^N^C) MLCT assignment. This is in stark contrast to [Ru(tpy)(bpy)Cl](+) and [Os(tpy)(bpy)Cl](+) (tpy = 2,2':6',2″-terpyridine, bpy = 2,2'-bipyridine) for which the lowest-energy transitions are assigned as dπ(Ru/Os) → π*(tpy) MLCT transitions. [Ru(II)(C^N^C)(N^N)L](n+) is emissive with emission maxima of around 600-700 nm observed upon photoexcitation of their dπ(Ru(II)) → π*(N^N) MLCT bands. The electronic structures for [Ru(C^N^C)(N^N)Cl](0) have also been probed by spectroelectrochemistry, electron paramagnetic resonance (EPR) spectroscopy, and DFT calculations, which reveal that the lowest unoccupied molecular orbitals (LUMOs) for [Ru(C^N^C)(N^N)Cl](+) are N^N-based. PMID:23952294

  10. Discovery and investigation of anticancer ruthenium-arene Schiff-base complexes via water-promoted combinatorial three-component assembly.

    PubMed

    Chow, Mun Juinn; Licona, Cynthia; Yuan Qiang Wong, Daniel; Pastorin, Giorgia; Gaiddon, Christian; Ang, Wee Han

    2014-07-24

    The structural diversity of metal scaffolds makes them a viable alternative to traditional organic scaffolds for drug design. Combinatorial chemistry and multicomponent reactions, coupled with high-throughput screening, are useful techniques in drug discovery, but they are rarely used in metal-based drug design. We report the optimization and validation of a new combinatorial, metal-based, three-component assembly reaction for the synthesis of a library of 442 Ru-arene Schiff-base (RAS) complexes. These RAS complexes were synthesized in a one-pot, on-a-plate format using commercially available starting materials under aqueous conditions. The library was screened for their anticancer activity, and several cytotoxic lead compounds were identified. In particular, [(η6-1,3,5-triisopropylbenzene)RuCl(4-methoxy-N-(2-quinolinylmethylene)aniline)]Cl (4) displayed low micromolar IC50 values in ovarian cancers (A2780, A2780cisR), breast cancer (MCF7), and colorectal cancer (HCT116, SW480). The absence of p53 activation or changes in IC50 value between p53+/+ and p53-/- cells suggests that 4 and possibly the other lead compounds may act independently of the p53 tumor suppressor gene frequently mutated in cancer.

  11. Biophysical studies of a ruthenium(II) polypyridyl complex binding to DNA and RNA prove that nucleic acid structure has significant effects on binding behaviors.

    PubMed

    Xu, Hong; Liang, Yi; Zhang, Peng; Du, Fen; Zhou, Bing-Rui; Wu, Jun; Liu, Jian-Hong; Liu, Zhi-Gang; Ji, Liang-Nian

    2005-08-01

    The interactions of a metal complex [Ru(phen)(2)PMIP](2+) {Ru=ruthenium, phen=1,10-phenanthroline, PMIP=2-(4-methylphenyl)imidazo[4,5-f]1,10-phenanthroline} with yeast tRNA and calf thymus DNA (CT DNA) have been investigated comparatively by UV-vis spectroscopy, fluorescence spectroscopy, viscosity measurements, isothermal titration calorimetry (ITC), as well as equilibrium dialysis and circular dichroism (CD). Spectroscopic studies together with ITC and viscosity measurements indicate that both binding modes of the Ru(II) polypyridyl complex to yeast tRNA and CT DNA are intercalation and yeast tRNA binding of the complex is stronger than CT DNA binding. ITC experiments show that the interaction of the complex with yeast tRNA is driven by a moderately favorable enthalpy decrease in combination with a moderately favorable entropy increase, while the binding of the complex to CT DNA is driven by a large favorable enthalpy decrease with a less favorable entropy increase. The results from equilibrium dialysis and CD suggest that both interactions are enantioselective and the Delta enantiomer of the complex may bind more favorably to both yeast tRNA and CT DNA than the Lambda enantiomer does, and that the complex is a better candidate for an enantioselective binder to yeast tRNA than to CT DNA. Taken together, these results indicate that the structures of nucleic acids have significant effects on the binding behaviors of metal complexes.

  12. Ruthenium(II) complexes of 1,3-thiazolidine-2-thione: Cytotoxicity against tumor cells and anti-Trypanosoma cruzi activity enhanced upon combination with benznidazole.

    PubMed

    Corrêa, Rodrigo S; da Silva, Monize M; Graminha, Angelica E; Meira, Cássio S; Santos, Jamyle A F Dos; Moreira, Diogo R M; Soares, Milena B P; Von Poelhsitz, Gustavo; Castellano, Eduardo E; Bloch, Carlos; Cominetti, Marcia R; Batista, Alzir A

    2016-03-01

    Three new mixed and mononuclear Ru(II) complexes containing 1,3-thiazolidine-2-thione (tzdtH) were synthesized and characterized by spectroscopic analysis, molar conductivity, cyclic voltammetry, high-resolution electrospray ionization mass spectra and X-ray diffraction. The complexes presented unique stereochemistry and the proposed formulae are: [Ru(tzdt)(bipy)(dppb)]PF6 (1), cis-[Ru(tzdt)2(PPh3)2] (2) and trans-[Ru(tzdt)(PPh3)2(bipy)]PF6 (3), where dppb=1,4-bis(diphenylphosphino)butane and bipy=2,2'-bipyridine. These complexes demonstrated strong cytotoxicity against cancer cell lines when compared to cisplatin. Specifically, complex 2 was the most potent cytotoxic agent against MCF-7 breast cells, while complexes 1 and 3 were more active in DU-145 prostate cells. Binding of complexes to ctDNA was determined by UV-vis titration and viscosity measurements and revealed binding constant (Kb) values in range of 1.0-4.9×10(3)M(-1), which are characteristic of compounds possessing weak affinity to ctDNA. In addition, these complexes presented antiparasitic activity against Trypanosoma cruzi. Specifically, complex 3 demonstrated strong potency, moderate selectivity index and acted in synergism with the approved antiparasitic drug, benznidazole. Additionally, complex 3 caused parasite cell death through a necrotic process. In conclusion, we demonstrated that Ru(II) complexes have powerful pharmacological activity, while the metal-free tzdtH does not provoke the same outcome. PMID:26795676

  13. Reaction of *NO Thiolate and Thiol Complexes: Elimination of PhSNO from W(phen)(CO)(2)(SPh)(2), CO from W(phen)(CO)(2)((-S)(2)Arene), and HNO from W(phen)(CO)(3)(RSH).

    PubMed

    Capps, Kenneth B.; Bauer, Andreas; Abboud, Khalil A.; Hoff, Carl D.

    1999-12-27

    Reaction of *NO with W(phen)(CO)(2)(SPh)(2) (phen = 1,10-phenanthroline) results in clean conversion to W(phen)(CO)(2)(NO)(SPh). Reduction of the W(II) bisthiolates to the W(0) nitrosyl thiolate occurs with simultaneous reductive elimination of PhS-NO, which is unstable but could be detected spectroscopically. Reaction of W(phen)(CO)(2)(1,2-S(2)-Arene), however, does not result in reductive elimination of either free or bound nitrosothiol. Carbon monoxide is displaced, forming W(phen)(NO)(2)(1,2-S(2)-Arene) (1,2-S(2)-Arene = 1,2-benzene dithiolate or toluene-3,4-dithiolate). Complexes of butanethiol and thiophenol W(phen)(CO)(3)(RSH) react with excess *NO to form nitrosyl thiolate complexes W(phen)(CO)(2)(NO)(SR). These reactions also produce N(2)O and HNO(2), which are attributed to decomposition of initially formed HNO. These observations indicate that *NO may be capable of direct attack on complexed thiols. Crystal structures of W(phen)(CO)(2)(NO)(SPh) and W(phen)(NO)(2)(toluene-3,4-dithiolate) are reported.

  14. Ruthenium(II) Complexes with 2-Phenylimidazo[4,5-f][1,10]phenanthroline Derivatives that Strongly Combat Cisplatin-Resistant Tumor Cells

    PubMed Central

    Zeng, Leli; Chen, Yu; Liu, Jiangping; Huang, Huaiyi; Guan, Ruilin; Ji, Liangnian; Chao, Hui

    2016-01-01

    Cisplatin was the first metal-based therapeutic agent approved for the treatment of human cancers, but its clinical activity is greatly limited by tumor drug resistance. This work utilized the parent complex [Ru(phen)2(PIP)]2+ (1) to develop three Ru(II) complexes (2–4) with different positional modifications. These compounds exhibited similar or superior cytotoxicities compared to cisplatin in HeLa, A549 and multidrug-resistant (A549R) tumor cell lines. Complex 4, the most potent member of the series, was highly active against A549R cancer cells (IC50 = 0.8 μM). This complex exhibited 178-fold better activity than cisplatin (IC50 = 142.5 μM) in A549R cells. 3D multicellular A549R tumor spheroids were also used to confirm the high proliferative and cytotoxic activity of complex 4. Complex 4 had the greatest cellular uptake and had a tendency to accumulate in the mitochondria of A549R cells. Further mechanistic studies showed that complex 4 induced A549R cell apoptosis via inhibition of thioredoxin reductase (TrxR), elevated intracellular ROS levels, mitochondrial dysfunction and cell cycle arrest, making it an outstanding candidate for overcoming cisplatin resistance. PMID:26763798

  15. Synthesis, characterization and DNA-binding studies of ruthenium(II) mixed-ligand complexes containing dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline

    NASA Astrophysics Data System (ADS)

    Peng, Bin; Chen, Xiang; Du, Ke-Jie; Yu, Bo-Le; Chao, Hui; Ji, Liang-Nian

    2009-11-01

    A novel ligand dipyrido[1,2,5]oxadiazolo[3,4-b]quinoxaline (dpoq) and its complexes [Ru(bpy) 2(dpoq)] 2+ and [Ru(phen) 2(dpoq)] 2+ (bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, electrospray mass spectra and 1H NMR. The interaction of Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by absorption spectroscopy, fluorescence spectroscopy, thermal denaturation and viscosity measurements. Results suggest that two Ru(II) complexes bind to DNA via an intercalative mode.

  16. New bipyridyl/phenanthroline ruthenium(II) and ruthenium(III) complexes possessing acetate appended thioether. Evidence for oxidative linkage isomerization

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Kumar, Ajay; Kumar, Rajeev

    2006-03-01

    The acetate bearing dithioether, sodium di(2-carboxymethylsufanyl)maleonitrile, L 1 upon reaction with [Ru II(bpy) 2Cl 2]·2H 2O, [Ru II(phen) 2Cl 2]·2H 2O, [Ru III(bpy) 2Cl 2] + or [Ru III(phen) 2Cl 2] + in methanol formed complexes of the type [(bpy) 2Ru{S 2(CH 2COO) 2C 2(CN) 2}], ( 1), [(phen) 2Ru{S 2(CH 2COO) 2C 2(CN) 2}], ( 2), [(bpy) 2Ru{(OOCCH 2) 2S 2C 2(CN) 2}] +, ( 5) and [(phen) 2Ru{(OOCCH 2) 2S 2C 2(CN) 2}] +, ( 6) respectively. Four other Ru(III) complexes with di(benzylsulfanyl)maleonitrile, L 2, [(bpy) 2Ru{S 2(PhCH 2)C 2(CN) 2}] 3+, ( 7) and [(phen) 2Ru{S 2(PhCH 2) 2C 2(CN) 2}] 3+, ( 8), and with acetate, [(bpy) 2Ru(OOCCH 3) 2] +, ( 9) and [(phen) 2Ru(OOCCH 3) 2] +, ( 10) were also synthesized. In the cyclic voltammetry, complexes ( 1) and ( 2) exhibited quasireversible oxidation waves at 1.01 and 1.02 V vs. Ag/AgCl over GC electrode in DMF, while the corresponding Ru(III) L 1 complexes ( 5) and ( 6) exhibit reversible oxidation at E1/2 0.59 and 0.58 V, respectively, under identical conditions. This is unlike the voltammetric behavior of the Ru(II) and Ru(III) L 2 complexes, wherein the complex pairs ( 3), ( 7) and ( 4), ( 8) exhibited identical voltammograms with single reversible one electron waves at E1/2 0.98 and 0.92 V, respectively under identical conditions. The voltammograms of Ru(II)-L 2 complexes (3) and (4) also became irreversible in presence of nearly four molar equivalent of sodium acetate. Hence, the irreversible redox behavior of complexes (1) and (2) has been interpreted in terms of rapid linkage isomerization, i.e. shift in κ 2-S,S' to κ 2-O,O' coordination, following the Ru(II)/Ru(III) electrode process. The electronic spectra of Ru(III)-L 1 complexes ( 5) and ( 6) resemble closely with that of ( 9) and ( 10) instead of Ru(III)-L 2 complexes ( 7) and ( 8), further supports proposed linkage isomerization. The cationic complexes were obtained as [PF 6] - salts and all compounds were characterized using analytical and spectral (IR

  17. Luminescent Ruthenium(II) Complex Bearing Bipyridine and N-Heterocyclic Carbene-based C∧N∧C Pincer Ligand for Live-Cell Imaging of Endocytosis

    NASA Astrophysics Data System (ADS)

    Tsui, Wai-Kuen; Chung, Lai-Hon; Wong, Matthew Man-Kin; Tsang, Wai-Him; Lo, Hoi-Shing; Liu, Yaxiang; Leung, Chung-Hang; Ma, Dik-Lung; Chiu, Sung-Kay; Wong, Chun-Yuen

    2015-03-01

    Luminescent ruthenium(II)-cyanide complex with N-heterocyclic carbene pincer ligand C∧N∧C = 2,6-bis(1-butylimidazol-2-ylidene)pyridine and 2,2'-bipyridine (bpy) shows minimal cytotoxicity to both human breast carcinoma cell (MCF-7) and human retinal pigmented epithelium cell (RPE) in a wide range of concentration (0.1-500 μM), and can be used for the luminescent imaging of endocytosis of the complex in these cells.

  18. DNA Binding and Photocleavage Properties, Cellular Uptake and Localization, and in-Vitro Cytotoxicity of Dinuclear Ruthenium(II) Complexes with Varying Lengths in Bridging Alkyl Linkers.

    PubMed

    Liu, Ping; Wu, Bao-Yan; Liu, Jin; Dai, Yong-Cheng; Wang, You-Jun; Wang, Ke-Zhi

    2016-02-15

    Two new dinuclear Ru(II) polypyridyl complexes containing three and ten methylene chains in their bridging linkers are synthesized and characterized. Their calf thymus DNA-binding and plasmid DNA photocleavage behaviors are comparatively studied with a previously reported, six-methylene-containing analog by absorption and luminescence spectroscopy, steady-state emission quenching by [Fe(CN)6](4-), DNA competitive binding with ethidium bromide, DNA viscosity measurements, DNA thermal denaturation, and agarose gel electrophoresis analyses. Theoretical calculations applying the density functional theory (DFT) method for the three complexes are also performed to understand experimentally observed DNA binding properties. The results show that the two complexes partially intercalate between the base pairs of DNA. Cellular uptake and colocalization studies have demonstrated that the complexes could enter HeLa cells efficiently and localize within lysosomes. The in-vitro antitumor activity against HeLa and MCF-7 tumor cells of the complexes are studied by MTT cytotoxic analysis. A new method, high-content analysis (HCA), is also used to assess cytotoxicity, apoptosis and cell cycle arrest of the three complexes. The results show that the lengths of the alkyl linkers could effectively tune their biological properties and that HCA is suitable for rapidly identifying cytotoxicity and can be substituted for MTT assays to evaluate the cell cytotoxicity of chemotherapeutic agents.

  19. Electronic structure, molecular electrostatic potential and spectral characteristics of pillar[6]arene hosts and their complexes with n-octyltriethylammonium ions.

    PubMed

    Peerannawar, Swarada R; Gejji, Shridhar P

    2012-06-28

    Electronic structure, charge distribution and (1)H NMR in pillar[6]arene (P6) conformers, their diisobutoxy derivatives and their host-guest complexes have been investigated by employing the density functional theory. It has been shown that a P6 conformer obtained by flipping of alternate hydroquinone units turns out to be of lowest energy, owing to the hydrogen bonded network at both rims of the host. As opposed to this, a conformer void of hydrogen bonding interactions has largely been destabilized. The O-HO interactions are analyzed using molecular electrostatic potential topography as a tool. Modification of a P6 host by substituting a diisobutoxy group at reactive phenols (DIBP6) renders rigid pillar-shape architecture to the host in which electron-rich regions are localized within the cavity and near portals. Complexation of n-octyltriethylammonium ions (n-OTEA) with P6 and DIBP6 reveals qualitatively different binding patterns. It has been shown that the conformer in which n-OTEA penetrates from the lower rim of the host and partially encapsulates within the P6 cavity turns out to be 1.4 kJ mol(-1) lower in energy than the complex showing complete guest encapsulation. Host-guest binding patterns, viz. encapsulation or portal interactions, can be distinguished from (1)H NMR chemical shifts. The shielding of ethyl and n-octyl chain protons in an n-OTEA⊂DIBP6 complex points to encapsulation of the guest which has been rationalized from natural bond orbital analyses. These inferences are in consonance with (1)H NMR experiments. PMID:22596047

  20. Synthesis, characterization, DNA binding, light switch "on and off", docking studies and cytotoxicity, of ruthenium(II) and cobalt(III) polypyridyl complexes.

    PubMed

    Reddy, M Rajender; Reddy, Putta Venkat; Kumar, Yata Praveen; Srishailam, A; Nambigari, Navaneetha; Satyanarayana, S

    2014-05-01

    The novel ligand (dmbip) 2-(4-N, N-dimethylbenzenamine)1H-imidazo[4, 5-f][1, 10]phenanthroline and its complexes [Ru(phen)2dmbip](2+) (1), [Ru(bpy)2dmbip](2+) (2), [Co(phen)2dmbip](3+) (3) and [Co(bpy)2dmbip](3+) (4) [where phen = 1, 10-phenanthroline, bpy = 2, 2'-bipyridine], have been synthesized and characterized by elemental analysis, IR, UV-Vis, (1)H NMR, (13)C NMR and Mass spectra. The DNA binding properties of the complexes were investigated by absorption, emission, quenching studies, light switch "on and off", salt dependent, sensor (cation and anion) studies, viscosity measurements, cyclic voltammetry, molecular modeling and docking studies. The four complexes were screened for Photo cleavage of pBR322 DNA, antimicrobial activity and cytotoxicity. The experimental results indicate that the four complexes can intercalate into DNA base pairs. The DNA-binding affinities of these complexes follow the order [Ru(phen)2dmbip](2+) > [Co(phen)2dmbip](3+) > [Ru(bpy)2dmbip](2+) > [Co(bpy)2dmbip](3+). PMID:24615259

  1. Ruthenium(II) Complexes Containing Lutidine-Derived Pincer CNC Ligands: Synthesis, Structure, and Catalytic Hydrogenation of C-N bonds.

    PubMed

    Hernández-Juárez, Martín; López-Serrano, Joaquín; Lara, Patricia; Morales-Cerón, Judith P; Vaquero, Mónica; Álvarez, Eleuterio; Salazar, Verónica; Suárez, Andrés

    2015-05-11

    A series of Ru complexes containing lutidine-derived pincer CNC ligands have been prepared by transmetalation with the corresponding silver-carbene derivatives. Characterization of these derivatives shows both mer and fac coordination of the CNC ligands depending on the wingtips of the N-heterocyclic carbene fragments. In the presence of tBuOK, the Ru-CNC complexes are active in the hydrogenation of a series of imines. In addition, these complexes catalyze the reversible hydrogenation of phenantridine. Detailed NMR spectroscopic studies have shown the capability of the CNC ligand to be deprotonated and get involved in ligand-assisted activation of dihydrogen. More interestingly, upon deprotonation, the Ru-CNC complex 5 e(BF4 ) is able to add aldimines to the metal-ligand framework to yield an amido complex. Finally, investigation of the mechanism of the hydrogenation of imines has been carried out by means of DFT calculations. The calculated mechanism involves outer-sphere stepwise hydrogen transfer to the C-N bond assisted either by the pincer ligand or a second coordinated H2 molecule.

  2. Poly(ε-caprolactone) decorated with one room-temperature red-emitting ruthenium(II) complex: synthesis, characterization, thermal and optical properties.

    PubMed

    Schulze, Marcus; Jäger, Michael; Schubert, Ulrich S

    2012-04-13

    The incorporation of room-temperature red-emissive [Ru(II)(dqp)(dqp-CH(2) OH)](2+) (dqp is 2,6-di(quinolin-8-yl)pyridine) in poly(ε-caprolactone) (PCL) is explored following two routes. First, the ring-opening polymerization of ε-caprolactone is investigated using the free ligand and the complex as initiators. Alternatively, the complexation strategy utilizing PCL-dqp as a macroligand is detailed. Both routes yield room-temperature emissive polymers centered at 400 nm (free ligand) and 680 nm (complex) in aerated solvent. DSC and TGA showed the typical properties of PCL, for example, the melting point (59 °C).

  3. Mononuclear and binuclear wirelike ruthenium(II) complexes with oligo-diethynyl-thiophene bridged back-to-back terpyridine ligands: synthesis and electrochemical and photophysical properties.

    PubMed

    Barbieri, Andrea; Ventura, Barbara; Barigelletti, Francesco; De Nicola, Antoinette; Quesada, Manuel; Ziessel, Raymond

    2004-11-15

    The syntheses, structural features, electrochemical behavior, absorption spectra, and photophysical properties of five mononuclear complexes [(terpy)Ru(terpy-DEDBT(n)-terpy)](2+), RuT(n), and five binuclear complexes [(terpy)Ru(terpy-DEDBT(n)-terpy)Ru(terpy)](4+), RuT(n)Ru, are reported, where n varies from 1 to 5 so that the metal-metal distance is estimated to be 42 A for the largest binuclear complex, RuT(5)Ru (terpy is 2,2':6',2"-terpyridine and DEDBT is 2,5-diethynyl-3,4-dibutylthiophene). The metal-centered oxidation potentials for the mononuclear and binuclear species are slightly more positive than for the reference [Ru(terpy)(2)](2+) complex, owing to the withdrawing nature of the back-to-back terpyridine ligands incorporating the repeat diethynyl-thiophene units. Comparison of the reduction potentials for the mononuclear and binuclear complexes reveals that the reduction steps are localized either at the terpy fragments of the T(n) ligands or at the terpy peripheral ligands. The spectroscopic results (absorption spectra at room temperature, luminescence spectra and lifetimes at room temperature and at 77 K) in acetonitrile solvent are consistent with the establishment of electronic delocalization within the oligomeric diethynyl-thiophene fragments (DEDBT(n)) of the T(n) ligands; however, the results also indicate that the terpy units of these ligands and the DEDBT(n)fragments are not strongly coupled. Both at room temperature and at 77 K, the (3)metal-to-ligand charge-transfer luminescence of RuT(n) and RuT(n)Ru complexes is strongly depressed in the larger species with respect to what happens for n < or = 2 (where the luminescence quantum yield is phi approximately 10(-4)); this is discussed in terms of the possible intervention of triplet levels localized at the oligothiophene DEDBT(n)(fragments. PMID:15530086

  4. Ruthenium(II) and osmium(II) vinyl complexes as highly sensitive and selective chromogenic and fluorogenic probes for the sensing of carbon monoxide in air.

    PubMed

    Toscani, Anita; Marín-Hernández, Cristina; Moragues, María E; Sancenón, Félix; Dingwall, Paul; Brown, Neil J; Martínez-Máñez, Ramón; White, Andrew J P; Wilton-Ely, James D E T

    2015-10-01

    The detection of carbon monoxide in solution and air has been achieved using simple, inexpensive systems based on the vinyl complexes [M(CHCHR)Cl(CO)(BTD)(PPh3 )2 ] (R=aryl, BTD=2,1,3-benzothiadiazole). Depending on the nature of the vinyl group, chromogenic and fluorogenic responses signalled the presence of this odourless, tasteless, invisible, and toxic gas. Solutions of the complexes in CHCl3 underwent rapid change between easily differentiated colours when exposed to air samples containing CO. More significantly, the adsorption of the complexes on silica produced colorimetric probes for the naked-eye detection of CO in the gas phase. Structural data for key species before and after the addition of CO were obtained by means of single X-ray diffraction studies. In all cases, the ruthenium and osmium vinyl complexes studied showed a highly selective response to CO with exceptionally low detection limits. Naked-eye detection of CO at concentrations as low as 5 ppb in air was achieved with the onset of toxic levels (i.e., 100 ppm), thus resulting in a remarkably clear colour change. Moreover, complexes bearing pyrenyl, naphthyl, and phenanthrenyl moieties were fluorescent, and greater sensitivities were achieved (through turn-on emission fluorescence) in the presence of CO both in solution and air. This behaviour was explored computationally using time-dependent density functional theory (TDDFT) experiments. In addition, the systems were shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. Supporting the metal complexes on cellulose strips for use in an existing optoelectronic device allows numerical readings for the CO concentration to be obtained and provision of an alarm system.

  5. Ruthenium(II) and osmium(II) vinyl complexes as highly sensitive and selective chromogenic and fluorogenic probes for the sensing of carbon monoxide in air.

    PubMed

    Toscani, Anita; Marín-Hernández, Cristina; Moragues, María E; Sancenón, Félix; Dingwall, Paul; Brown, Neil J; Martínez-Máñez, Ramón; White, Andrew J P; Wilton-Ely, James D E T

    2015-10-01

    The detection of carbon monoxide in solution and air has been achieved using simple, inexpensive systems based on the vinyl complexes [M(CHCHR)Cl(CO)(BTD)(PPh3 )2 ] (R=aryl, BTD=2,1,3-benzothiadiazole). Depending on the nature of the vinyl group, chromogenic and fluorogenic responses signalled the presence of this odourless, tasteless, invisible, and toxic gas. Solutions of the complexes in CHCl3 underwent rapid change between easily differentiated colours when exposed to air samples containing CO. More significantly, the adsorption of the complexes on silica produced colorimetric probes for the naked-eye detection of CO in the gas phase. Structural data for key species before and after the addition of CO were obtained by means of single X-ray diffraction studies. In all cases, the ruthenium and osmium vinyl complexes studied showed a highly selective response to CO with exceptionally low detection limits. Naked-eye detection of CO at concentrations as low as 5 ppb in air was achieved with the onset of toxic levels (i.e., 100 ppm), thus resulting in a remarkably clear colour change. Moreover, complexes bearing pyrenyl, naphthyl, and phenanthrenyl moieties were fluorescent, and greater sensitivities were achieved (through turn-on emission fluorescence) in the presence of CO both in solution and air. This behaviour was explored computationally using time-dependent density functional theory (TDDFT) experiments. In addition, the systems were shown to be selective for CO over all other gases tested, including water vapour and common organic solvents. Supporting the metal complexes on cellulose strips for use in an existing optoelectronic device allows numerical readings for the CO concentration to be obtained and provision of an alarm system. PMID:26270512

  6. Luminescent Ruthenium(II) Complex Bearing Bipyridine and N-Heterocyclic Carbene-based C∧N∧C Pincer Ligand for Live-Cell Imaging of Endocytosis

    PubMed Central

    Tsui, Wai-Kuen; Chung, Lai-Hon; Wong, Matthew Man-Kin; Tsang, Wai-Him; Lo, Hoi-Shing; Liu, Yaxiang; Leung, Chung-Hang; Ma, Dik-Lung; Chiu, Sung-Kay; Wong, Chun-Yuen

    2015-01-01

    Luminescent ruthenium(II)-cyanide complex with N-heterocyclic carbene pincer ligand C∧N∧C = 2,6-bis(1-butylimidazol-2-ylidene)pyridine and 2,2′-bipyridine (bpy) shows minimal cytotoxicity to both human breast carcinoma cell (MCF-7) and human retinal pigmented epithelium cell (RPE) in a wide range of concentration (0.1–500 μM), and can be used for the luminescent imaging of endocytosis of the complex in these cells. PMID:25765974

  7. Amino-functionalized pillar[5]arene.

    PubMed

    Strutt, Nathan L; Zhang, Huacheng; Schneebeli, Severin T; Stoddart, J Fraser

    2014-08-25

    The recently introduced pillar[n]arenes have provided chemists with receptors that, when incorporated into materials, confer unique properties upon them. The symmetrical rims and cylindrical shape of pillar[5]arene begs the question--can these pillar-like receptors be linked covalently end-to-end in order to create tubular structures by a growth-from-template approach? In our efforts to produce these one-dimensional extended structures, we have developed a new method of functionalizing pillar[5]arene in which one of the five hydroquinone units is converted into a diaminobenzoquinone analogue. The resulting diaminopillar[5]arene derivative, which undergoes a stereochemical inversion process that is slow on the (1)H NMR timescale, can be chemically modified yet further in a direction that is orthogonal to the plane of its methylene bridging carbons through the formation of oxazole heterocycles. This strategy has been employed to create rigid oligomers that resemble one-dimensional tubular arrays. As a proof-of-principle, a rigid pillar[5]arene dimer has been isolated and characterized in the solution state as a 1:1 complex with an extended viologen for which it acts as a receptor.

  8. The effects of linear assembly of two carbazole groups on acid-base and DNA-binding properties of a ruthenium(II) complex.

    PubMed

    Chen, Xi; Xue, Long-Xin; Ju, Chun-Chuan; Wang, Ke-Zhi

    2013-07-01

    A novel Ru(II) complex of [Ru(bpy)2(Hbcpip)](ClO4)2 {where bpy=2,2-bipyridine, Hbcpip=2-(4-(9H-3,9'-bicarbazol-9-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} is synthesized and characterized. Calf-thymus DNA-binding properties of the complex were studied by UV-vis absorption and luminescence titrations, steady-state emission quenching by [Fe(CN)6](4-), DNA competitive binding with ethidium bromide, thermal denaturation and DNA viscosity measurements. The results indicate that the complex partially intercalated into the DNA with a binding constant of (5.5±1.4)×10(5) M(-1) in buffered 50 mM NaCl. The acid-base properties of the complex were also studied by UV-visible and luminescence spectrophotometric pH titrations, and ground- and excited-state acidity ionization constant values were derived.

  9. The effects of linear assembly of two carbazole groups on acid-base and DNA-binding properties of a ruthenium(II) complex

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Xue, Long-Xin; Ju, Chun-Chuan; Wang, Ke-Zhi

    2013-07-01

    A novel Ru(II) complex of [Ru(bpy)2(Hbcpip)](ClO4)2 {where bpy = 2,2-bipyridine, Hbcpip = 2-(4-(9H-3,9'-bicarbazol-9-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline} is synthesized and characterized. Calf-thymus DNA-binding properties of the complex were studied by UV-vis absorption and luminescence titrations, steady-state emission quenching by [Fe(CN)6]4-, DNA competitive binding with ethidium bromide, thermal denaturation and DNA viscosity measurements. The results indicate that the complex partially intercalated into the DNA with a binding constant of (5.5 ± 1.4) × 105 M-1 in buffered 50 mM NaCl. The acid-base properties of the complex were also studied by UV-visible and luminescence spectrophotometric pH titrations, and ground- and excited-state acidity ionization constant values were derived.

  10. Monometallic osmium(II) complexes with bis(N-methylbenzimidazolyl)benzene or -pyridine: a comparison study with ruthenium(II) analogues.

    PubMed

    Shao, Jiang-Yang; Zhong, Yu-Wu

    2013-06-01

    Seven bis-tridentate osmium complexes with Mebib or Mebip (Mebib is the 2-deprotonated form of 1,3-bis(N-methylbenzimidazolyl)benzene and Mebip is bis(N-methylbenzimidazolyl)pyridine) have been prepared, and their electrochemical and spectroscopic properties are compared with ruthenium structural analogues. Among them, four complexes have the [Os(NCN)(NNN)]-type coordination, including [Os(Mebib)(Mebip)](PF6)2 (1(PF6)2), [Os(dpb)(Mebip)](PF6) (2(PF6), dpb is the 2-deprotonated form of 1,3-di(pyrid-2-yl)benzene), [Os(Mebib)(ttpy)](PF6) (3(PF6), ttpy = 4'-tolyl-2,2':6',2"-terpyridine), and [Os(dpb)(ttpy)](PF6) (4(PF6)). The other three complexes are [Os(Mebip)2](PF6)2 (5(PF6)2), [Os(Mebip)(tpy)](PF6)2 (6(PF6)2, tpy = 2,2':6',2"-terpyridine), and [Os(ttpy)2](PF6)2 (7(PF6)2) with the [Os(NNN)(NNN)]-type coordination. Single crystals of 2(PF6) and 6(PF6)2 have been obtained, and their structures are studied by X-ray crystallographic analysis. The Os(II/III) redox potentials of 1(PF6)2 to 7(PF6)2 progressively increase from +0.04, +0.23, +0.24, +0.36, +0.56, +0.79 to +0.94 V vs Ag/AgCl, which are 200-300 mV less positive relative to the Ru(II/III) potentials of their ruthenium counterparts. The highest occupied molecular orbital energy levels of 1(+)-7(2+) are calculated to vary in a descending order. The ruthenium and osmium complexes have singlet metal-to-ligand charge-transfer (MLCT) transitions of similar energies and band shapes, while the osmium complexes display additional (3)MLCT transitions in the lower-energy region. Complexes 6(PF6)2 and 7(PF6)2 emit weakly at 780 and 740 nm, respectively. Complex 1(PF6)2 was synthesized as the oxidized Os(III) salt because of the low Os(II/III) potential. The transformation of 1(2+) to 1(+) by chemical reduction or electrolysis led to the emergence of the (1)MLCT transitions in the visible region.

  11. Noncovalent Ruthenium(II) Complexes-Single-Walled Carbon Nanotube Composites for Bimodal Photothermal and Photodynamic Therapy with Near-Infrared Irradiation.

    PubMed

    Zhang, Pingyu; Huang, Huaiyi; Huang, Juanjuan; Chen, Hongmin; Wang, Jinquan; Qiu, Kangqiang; Zhao, Donglei; Ji, Liangnian; Chao, Hui

    2015-10-21

    To enhance the efficacy and optimize the treatment of cancers, the integration of multimodal treatment strategies leading to synergistic effects is a promising approach. The coassembly of multifunctional agents for systematic therapies has received considerable interest in cancer treatment. Herein, Ru(II) complex-functionalized single-walled carbon nanotubes (Ru@SWCNTs) are developed as nanotemplates for bimodal photothermal and two-photon photodynamic therapy (PTT-TPPDT). SWCNTs have the ability to load a great amount of Ru(II) complexes (Ru1 or Ru2) via noncovalent π-π interactions. The loaded Ru(II) complexes are efficiently released by the photothermal effect of irradiation from an 808 nm diode laser (0.25 W/cm(2)). The released Ru(II) complexes produce singlet oxygen species ((1)O2) upon two-photon laser irradiation (808 nm, 0.25 W/cm(2)) and can be used as a two-photon photodynamic therapy (TPPDT) agent. Based on the combination of photothermal therapy and two-photon photodynamic therapy, Ru@SWCNTs have greater anticancer efficacies than either PDT using Ru(II) complexes or PTT using SWCNTs in two-dimensional (2D) cancer cell and three-dimensional (3D) multicellular tumor spheroid (MCTS) models. Furthermore, in vivo tumor ablation is achieved with excellent treatment efficacy under a diode laser (808 nm) irradiation at the power density of 0.25 W/cm(2) for 5 min. This study examines an efficacious bimodal PTT and TPPDT nanoplat form for the development of cancer therapeutics.

  12. New series of ruthenium(II) and osmium(II) complexes showing solid-state phosphorescence in far-visible and near-infrared.

    PubMed

    Chen, Jing-Lin; Chi, Yun; Chen, Kellen; Cheng, Yi-Ming; Chung, Min-Wen; Yu, Ya-Chien; Lee, Gene-Hsiang; Chou, Pi-Tai; Shu, Ching-Fong

    2010-02-01

    A new Ru(II) complex, [Ru(fpbpymH)(2)]Cl(2) (1), in which fpbpymH = [5-(trifluoromethyl)pyrazol-3-yl](2,2'-bipyrid-6-yl)methane, was prepared by the treatment of [Ru(DMSO)(4)Cl(2)] with 2 equiv of the terdentate chelate fpbpymH in refluxing ethanol. A single-crystal X-ray diffraction study of 1 revealed a distorted octahedral Ru(II) framework, showing strong N-H...Cl hydrogen bonding between the fpbpymH ligand and Cl anions. In the presence of Na(2)CO(3), the methylene linkers of chelates in 1 underwent stepwise oxygenation, forming the charge-neutral complexes [Ru(fpbpym)(fpbpyk)] (2) and [Ru(fpbpyk)(2)] (3) [fpbpykH = [5-(trifluoromethyl)pyrazol-3-yl](2,2'-bipyrid-6-yl) ketone] in sequence. The respective charge-neutral Os(II) complex [Os(fpbpyk)(2)] (4) was also isolated by the treatment of OsCl(3).3H(2)O with 2 equiv of the terdentate chelate fpbpymH. Electrochemical analysis indicated that the introduction of the electron-withdrawing ketone group in 2-4 increased the metal-based oxidation potential in sequence. For the photophysical properties, complexes 1-4 are essentially nonluminescent in solution (e.g., CH(2)Cl(2) or MeOH) at room temperature, but all exhibit 600-1100 nm phosphorescence with moderate intensity for the powdery, solid sample at room temperature. The trend in terms of the emission peak wavelength of 1 (666 nm) < 3 (795 nm) < 2 (810 nm) < 4 (994 nm) among titled complexes is in agreement with the corresponding onset of absorption spectra as well as the time-dependent density functional theory calculation of 1 < 3 < 2 < 4. PMID:20030393

  13. Carriers for metal complexes on tumour cells: the effect of cyclodextrins vs CNTs on the model guest phenanthroline-5,6-dione trithiacyclononane ruthenium(II) chloride.

    PubMed

    Braga, Susana S; Marques, Joana; Heister, Elena; Diogo, Cátia V; Oliveira, Paulo J; Paz, Filipe A Almeida; Santos, Teresa M; Marques, Maria Paula M

    2014-06-01

    The complex [Ru[9]aneS3(pdon)Cl]Cl (pdon = 1,10-phenanthroline-5,6-dione) was readily obtained from the stoichiometric reaction of Ru[9]aneS3(dmso)Cl2 with pdon. Recrystallisation in ethanol using salicylic acid as a co-crystallisation helper afforded single-crystals suitable for the collection of X-ray diffraction data which afforded a reasonable structural description. Two different kinds of molecular carriers were tested as vehicles for this complex: carbon nanotubes (CNTs) and cyclodextrins. CNTs had an insufficient loading rate for the ruthenium complex at CNT concentrations deemed non-cytotoxic on cultured cells. The cyclodextrin (CD) carriers, β-CD and TRIMEB (standing for permethylated β-CD), were able to form two adducts, studied by powder X-ray diffraction, thermogravimetric analysis (TGA), (13)C{(1)H} CP/MAS NMR and FT-IR spectroscopies. The DNA thermal denaturation studies showed that the complex 1 is able to intercalate with DNA. The in vitro cytotoxicity of the free complex [Ru[9]aneS3(pdon)Cl]Cl (1) and of its two CD adducts (2 and 3) was assessed on both rodent and human cell lines. By using the mouse K1735-M2 melanoma cell line and the non-tumour rat H9c2 cardiomyoblasts, the results showed that 1 and 2 significantly inhibited the growth of the tumour cell line while displaying a good safety profile on cardiomyoblasts. Compound 3 at 100 μM inhibited the proliferation of both cell lines, with a higher activity towards the melanoma cell line. The cytotoxicity of the compounds 1-3 was further assessed on human breast cancer cell lines. Against the MDA-MB-231 line, growth inhibition occurred only with 1 and 3 at the incubation time of 96 h, both with approximate inhibition rates of 50 %; against the MCF-7 line, mild cytotoxicity was observed at 48 h of incubation, with IC50 values calculated above 100 μM for 1, 2 and 3.

  14. Effect of arene substituents and temperature on the arene replacement reactions of ((eta/sup 5/-C/sub 5/H/sub 5/)Fe(eta/sup 6/-arene))/sup +/ and ((eta/sup 5/-C/sub 5/H/sub 5/)Ru(eta/sup 6/-arene))/sup +/

    SciTech Connect

    McNair, A.M.; Schrenk, J.L.; Mann, K.R.

    1984-08-15

    Results are reported for investigations to identify the photoactive excited states, delineate substitutent effects, and determine the temperature dependence of the quantum yield for Fe(II)- and Ru(II)-substituted arene complexes. These studies indicate metal-arene bond cleavage for complexes of both metals is nearly complete in the reactive excited state, but nucleophilic interactions of the medium in the transition state ultimately control the quantum yield of arene release for a given complex.

  15. Nature-Inspired, Highly Durable CO2 Reduction System Consisting of a Binuclear Ruthenium(II) Complex and an Organic Semiconductor Using Visible Light.

    PubMed

    Kuriki, Ryo; Matsunaga, Hironori; Nakashima, Takuya; Wada, Keisuke; Yamakata, Akira; Ishitani, Osamu; Maeda, Kazuhiko

    2016-04-20

    A metal-free organic semiconductor of mesoporous graphitic carbon nitride (C3N4) coupled with a Ru(II) binuclear complex (RuRu') containing photosensitizer and catalytic units selectively reduced CO2 into HCOOH under visible light (λ > 400 nm) in the presence of a suitable electron donor with high durability, even in aqueous solution. Modification of C3N4 with Ag nanoparticles resulted in a RuRu'/Ag/C3N4 photocatalyst that exhibited a very high turnover number (>33000 with respect to the amount of RuRu'), while maintaining high selectivity for HCOOH production (87-99%). This turnover number was 30 times greater than that reported previously using C3N4 modified with a mononuclear Ru(II) complex, and by far the highest among the metal-complex/semiconductor hybrid systems reported to date. The results of photocatalytic reactions, emission decay measurements, and time-resolved infrared spectroscopy indicated that Ag nanoparticles on C3N4 collected electrons having lifetimes of several milliseconds from the conduction band of C3N4, which were transferred to the excited state of RuRu', thereby promoting photocatalytic CO2 reduction driven by two-step photoexcitation of C3N4 and RuRu'. This study also revealed that the RuRu'/Ag/C3N4 hybrid photocatalyst worked efficiently in water containing a proper electron donor, despite the intrinsic hydrophobic nature of C3N4 and low solubility of CO2 in an aqueous environment.

  16. Selective Formic Acid Production via CO2 Reduction with Visible Light Using a Hybrid of a Perovskite Tantalum Oxynitride and a Binuclear Ruthenium(II) Complex.

    PubMed

    Yoshitomi, Fumiaki; Sekizawa, Keita; Maeda, Kazuhiko; Ishitani, Osamu

    2015-06-17

    A hybrid material consisting of CaTaO2N (a perovskite oxynitride semiconductor having a band gap of 2.5 eV) and a binuclear Ru(II) complex photocatalytically produced HCOOH via CO2 reduction with high selectivity (>99%) under visible light (λ>400 nm). Results of photocatalytic reactions, spectroscopic measurements, and electron microscopy observations indicated that the reaction was driven according to a two-step photoexcitation of CaTaO2N and the Ru photosensitizer unit, where Ag nanoparticles loaded on CaTaO2N with optimal distribution mediated interfacial electron transfer due to reductive quenching.

  17. Two-photon absorption properties of iron(II) and ruthenium(II) trischelate complexes of 2,2':4,4' ':4',4' ''-quaterpyridinium ligands.

    PubMed

    Coe, Benjamin J; Samoc, Marek; Samoc, Anna; Zhu, Lingyun; Yi, Yuanping; Shuai, Zhigang

    2007-01-25

    A series of RuII or FeII trischelate complex salts containing N-methyl/aryl-2,2':4,4' ':4',4' ''-quaterpyridinium ligands that has previously been subjected to quadratic nonlinear optical studies (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 13399) has now been investigated for two-photon absorbing behavior. Z-scan measurements using a 750 nm laser afford reasonably large two-photon absorption (2PA) cross-sections sigma2 of ca. 62-180 GM for the RuII complexes, but only very weak 2PA is observed for the FeII compounds. The excited-state and 2PA properties of the representative chromophore [RuII(Me2Qpy2+)3]8+ (Me2Qpy2+=N' ',N' ''-dimethyl-2,2':4,4' ':4',4' ''-quaterpyridinium) have also been investigated by using semiempirical intermediate neglect of differential overlap/multireference-determinant single and double configuration interaction computations with the optimized geometry obtained via density functional theory. The calculated sigma2 value of ca. 624 GM at 1.70 eV for this metal-to-ligand charge-transfer chromophore is about 10 times larger than that obtained from the Z-scan studies. PMID:17228896

  18. Combining Ruthenium(II) Complexes with Metal-Organic Frameworks to Realize Effective Two-Photon Absorption for Singlet Oxygen Generation.

    PubMed

    Zhang, Wenxiang; Li, Bin; Ma, Heping; Zhang, Liming; Guan, Yunlong; Zhang, Yihe; Zhang, Xindan; Jing, Pengtao; Yue, Shumei

    2016-08-24

    Singlet oxygen ((1)O2), as a reactive oxygen species, has garnered serious attention in physical, chemical, and biological studies. In this paper, we designed and synthesized a new type of singlet-oxygen generation system by exchanging cationic ruthenium complexes (RCs) into anionic bio-MOF-1. The resulting bio-MOF-1&RCs can be used as effective photocatalysts for generation of singlet oxygen under both single-photon and two-photon excitation. Especially, the excellent two-photon absorption (TPA) behavior of bio-MOF-1&RCs aroused our interest greatly because their two-photon absorption band lies in the optical window of biological tissue. Here, we measured the ability of bio-MOF-1&RCs to generate (1)O2 by irradiation under both 490 and 800 nm wavelength light in DMF. 1,3-Diphenylisobenzofuran (DPBF) and 2',7'-dichlorofluorescein (DCFH) were used as typical (1)O2 traps to detect and evaluate the efficiency of generation of (1)O2 under single-photon and two-photon excitation, respectively. Results indicated that bio-MOF-1&[Ru(phen)3](2+) was able to effectively generate (1)O2 under both conditions. Our work creates a novel synergistic TPA system with the excellent photophysical properties of RCs and the unique microporous structure benefit of MOFs, which may open a new avenue for creation of a cancer treatment system with both photodynamic therapy and chemotherapy. PMID:27483010

  19. Oxidative addition of allylic halides to ruthenium(II) compounds. Preparation, reactions, and X-ray crystallographic structure of ruthenium(IV)-allyl complexes

    SciTech Connect

    Nagashima, Hideo; Mukai, Katsunori; Shiota, Yusuke; Yamaguchi, Keitaro; Ara, Kenichi; Fukahori, Takahiko; Itoh, Kenji ); Suzuki, Hiroharu; Akita, Munetaka; Moro-oka, Yoshihiko )

    1990-03-01

    The oxidative addition of allylic halides to (C{sub 5}R{sub 5})RuL{sub 2}X (R = H, Me; L = CO, PPh{sub 3}) gave new Ru(IV)-{eta}{sup 3}-allyl complexes, (C{sub 5}R{sub 5})RuX{sub 2}({eta}{sup 3}-allyl). An X-ray structure determination was carried out on (C{sub 5}Me{sub 5})RuBr{sub 2}({eta}{sup 3}-C{sub 3}H{sub 5}), indicating a pseudo-piano-stool structure having two Br atoms and two terminal carbons of the endo-{eta}{sup 3}-allyl ligand located at the basal positions. There is a crystal mirror plane bisecting the pentamethylcyclopentadienyl and the {pi}-allyl ligands. Crystal data: orthorhombic, space group P2{sub 1}2{sub 1}2{sub 1}, a = 22.738 (1) {angstrom}, b = 13.367 (7) {angstrom}, c = 9.383 (1) {angstrom}, Z = 4., data refined to R = 0.0695. Its {sup 1}H and {sup 13}C NMR spectra showed symmetric allyl signals, supporting that the above-described piano-stool structure is maintained even in solution.

  20. Superior Light-Harvesting Heteroleptic Ruthenium(II) Complexes with Electron-Donating Antennas for High Performance Dye-Sensitized Solar Cells.

    PubMed

    Chen, Wang-Chao; Kong, Fan-Tai; Li, Zhao-Qian; Pan, Jia-Hong; Liu, Xue-Peng; Guo, Fu-Ling; Zhou, Li; Huang, Yang; Yu, Ting; Dai, Song-Yuan

    2016-08-01

    Three heteroleptic polypyridyl ruthenium complexes, RC-41, RC-42, and RC-43, with efficient electron-donating antennas in the ancillary ligands were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cell. All the RC dye sensitizers showed remarkable light-harvesting capacity and broadened absorption range. Significantly, RC-43 obtained the lower energy metal-ligand charge transfer (MLCT) band peaked at 557 nm with a high molar extinction coefficient of 27 400 M(-1) cm(-1). In conjunction with TiO2 photoanode of submicrospheres and iodide-based electrolytes, the DSSCs sensitizing with the RC sensitizers, achieved impressively high short-circuit current density (19.04 mA cm(-2) for RC-41, 19.83 mA cm(-2) for RC-42, and 20.21 mA cm(-2) for RC-43) and power conversion efficiency (10.07% for RC-41, 10.52% for RC-42, and 10.78% for RC-43). The superior performances of RC dye sensitizers were attributed to the enhanced light-harvesting capacity and incident-photon-to-current efficiency (IPCE) caused by the introduction of electron-donating antennas in the ancillary ligands. The interfacial charge recombination/regeneration kinetics and electron lifetime were further evaluated by the electrochemical impedance spectroscopy (EIS) and transient absorption spectroscopy (TAS). These data decisively revealed the dependences on the photovoltaic performance of ruthenium sensitizers incorporating electron-donating antennas. PMID:27409513

  1. Superior Light-Harvesting Heteroleptic Ruthenium(II) Complexes with Electron-Donating Antennas for High Performance Dye-Sensitized Solar Cells.

    PubMed

    Chen, Wang-Chao; Kong, Fan-Tai; Li, Zhao-Qian; Pan, Jia-Hong; Liu, Xue-Peng; Guo, Fu-Ling; Zhou, Li; Huang, Yang; Yu, Ting; Dai, Song-Yuan

    2016-08-01

    Three heteroleptic polypyridyl ruthenium complexes, RC-41, RC-42, and RC-43, with efficient electron-donating antennas in the ancillary ligands were designed, synthesized, and characterized as sensitizers for dye-sensitized solar cell. All the RC dye sensitizers showed remarkable light-harvesting capacity and broadened absorption range. Significantly, RC-43 obtained the lower energy metal-ligand charge transfer (MLCT) band peaked at 557 nm with a high molar extinction coefficient of 27 400 M(-1) cm(-1). In conjunction with TiO2 photoanode of submicrospheres and iodide-based electrolytes, the DSSCs sensitizing with the RC sensitizers, achieved impressively high short-circuit current density (19.04 mA cm(-2) for RC-41, 19.83 mA cm(-2) for RC-42, and 20.21 mA cm(-2) for RC-43) and power conversion efficiency (10.07% for RC-41, 10.52% for RC-42, and 10.78% for RC-43). The superior performances of RC dye sensitizers were attributed to the enhanced light-harvesting capacity and incident-photon-to-current efficiency (IPCE) caused by the introduction of electron-donating antennas in the ancillary ligands. The interfacial charge recombination/regeneration kinetics and electron lifetime were further evaluated by the electrochemical impedance spectroscopy (EIS) and transient absorption spectroscopy (TAS). These data decisively revealed the dependences on the photovoltaic performance of ruthenium sensitizers incorporating electron-donating antennas.

  2. Zinc(II), iron(II/III) and ruthenium(II) complexes of o-phenylenediamine derivatives: oxidative dehydrogenation and photoluminescence.

    PubMed

    Chaudhuri, Satyabrata; Patra, Sarat Chandra; Saha, Pinaki; Saha Roy, Amit; Maity, Suvendu; Bera, Sachinath; Saha Sardar, Pinki; Ghosh, Sanjib; Weyhermüller, Thomas; Ghosh, Prasanta

    2013-11-14

    Reactions of benzoyl pyridine, o-phenylenediamine and anhydrous ZnX2 in methanol afford imine complexes [Zn(L1)X2] (X = Cl, 1; X = Br, 2) in good yields (L1 = (E)-N(1)-(phenyl(pyridin-2-yl)methylene)benzene-1,2-diamine). The reduction of 1 with NaBH4 affords (E)-N(1)-(phenyl(pyridine-2-yl)methylene)benzene-1,2-diamine (L2H). The reaction of L2H with [Ru(II)(PPh3)3Cl2] results in the oxidative dehydrogenation to L1 generating cis-[Ru(II)(L1)(PPh3)Cl2] (3). The reaction of L2H with salicylaldehyde affords (E)-2-(((2-((phenyl(pyridin-2-yl)methyl)amino)phenyl)imino)methyl)phenol (L3H2). The reaction of L3H2 with anhydrous FeCl3 in CH3OH affords cis-[Fe(III)(L3H(-))Cl2] (4). Reaction of L3H2 with [Ru(II)(PPh3)3Cl2] results in the oxidative dehydrogenation to diimine, L4H, affording trans-[Ru(II)(L4(-))(PPh3)2](+), which is isolated as trans-[Ru(II)(L4(-))(PPh3)2]PF6 (5(+)PF6(-)) (L4H = 2-((E)-(2-((E)-phenyl(pyridin-2-yl)methyleneamino)phenylimino)methyl)phenol). The reduction of L3H2 with NaBH4 produces 2-(((2-((phenyl(pyridin-2-yl)methyl)amino)phenyl)amino)methyl)phenol (L5H3). With iron(III) L5H3 undergoes oxidative dehydrogenation to L3H2 affording 4, while with [Ru(II)(PPh3)3Cl2], L5H3 undergoes 4e + 4H(+) transfer giving 5(+). A fluid solution of L3H2 at 298 K exhibits an emission band at 470 nm (λ(ex) = 330 nm, τ1 = 3.70 ns) and a weaker band at 525 nm (λ(ex) = 330, 390 nm, τ1 = 1.1 ns) at higher concentrations due to molecular aggregation, which are temperature dependent. 4 is brightly emissive (λ(ex) = 330 nm, λ(em) = 450 nm, Φ = 0.586, τ1 = 3.70 ns). Time resolved emission spectra (TRES) and lifetime measurements confirm that the lower energy absorption band of L3H2 at 390 nm, which is absent in complex 4, has a larger non-radiative rate constant (k(nr)). The redox innocent Al(III) adduct of L3H2 is fluorescent (λ(ex) = 330 nm, λ(em) = 450 nm, τ1 = 3.70 ns). On the contrary, the cis-[Fe(II)(L3H(-))Cl2](-) and cis-[Co(L3H(-))Cl2](-) analogues are non

  3. Combined homogeneous and heterogeneous catalysts. Rhodium and platinum isocyanide complexes tethered on silica-supported metal heterogeneous catalysts: Arene and cyclohexanone hydrogenation

    SciTech Connect

    Gao, H.; Angelici, R.J. |

    1999-03-15

    Rhodium and platinum isocyanide complexes RhCl(CO)[CN(CH{sub 2}){sub 3}Si(OC{sub 2}H{sub 5}){sub 3}]{sub 2} (Rh-CNR{sub 2}), RhCl[CN(CH{sub 2}){sub 3}Si(OC{sub 2}H{sub 5}){sub 3}]{sub 3} (Rh-CNR{sub 3}), and PtCl{sub 2}[CN(CH{sub 2}){sub 3}Si(OC{sub 2}H{sub 5}){sub 3}]{sub 2} (Pt-CNR{sub 2}) were tethered to the silica-supported metal heterogeneous catalysts M-SiO{sub 2} (M = Pd, Pt, Ru) to give the TCSM (tethered complex on supported metal) catalysts Rh-CNR{sub 2}/Pd-SiO{sub 2}, Rh-CNR{sub 3}/M-SiO{sub 2} (M = Pd, Pt, Ru), and Pt-CNR{sub 2}/Pd-SiO{sub 2}. These TCSM catalysts were used to catalyze the hydrogenation of arenes (Rh-CNR{sub 2}/Pd-SiO{sub 2} and Rh-CNR{sub 3}/M-SiO{sub 2}) and cyclohexanone (Pt-CNR{sub 2}/Pd-SiO{sub 2}) under the mild conditions of 40 C and 1 atm. They exhibit activities that are higher than those of the separate homogeneous rhodium (or platinum) isocyanide complex, the separate silica-supported metal heterogeneous catalyst, or the rhodium (or platinum) complex catalyst tethered on just SiO{sub 2}. The activities of the TCSM catalysts are strongly affected by the nature and loading of the supported metal in the catalyst. Among the three silica-supported metal M-SiO{sub 2} (M = Pd, Pt, Ru) catalysts, the rhodium complex Rh-CNR{sub 3} tethered on Pd-SiO{sub 2} exhibits the highest activity for the hydrogenation of toluene (TOF = 5.5 mol H{sub 2}/(mol Rh min) and TO = 2,420 mol H{sub 2}/mol Rh during 8.5 h). The Rh-CNR{sub 3}/Pd-SiO{sub 2} catalyst with 10 wt % Pd is more active than its counterparts with higher or lower palladium loadings. IR (DRIFT) spectral studies of the TCSM catalysts before and after being used for toluene hydrogenation show that the isocyanide ligands remain coordinated to the rhodium (or platinum) center even after extended use. Atomic emission spectroscopic analysis of hydrogenation solutions shows that there is no rhodium (or platinum) leaching into the solutions.

  4. Reaction-based turn-on electrochemiluminescent sensor with a ruthenium(II) complex for selective detection of extracellular hydrogen sulfide in rat brain.

    PubMed

    Yue, Xiaoxiao; Zhu, Ziyu; Zhang, Meining; Ye, Zhiqiang

    2015-02-01

    Hydrogen sulfide (H2S) has been drawing increasing attention because it plays an important role in the nervous system and has been deemed as a third endogenous gas signal molecule besides nitric oxide (NO) and carbon monoxide (CO). In this study, using a ruthenium complex, [Ru(bpy)2(bpy-DPA)Cu](4+) (where bpy = 2,2'-bipyridine and bpy-DPA = 4-methyl-4'-[N,N-bis(2-picolyl)aminomethylene]-2,2'-bipyridine) as recognition unit, we report a new reaction-based turn-on electrochemiluminescent (ECL) sensor to selectively detect extracellular H2S in rat brain, coupled with in vivo microdialysis for dialysate sampling. To prepare the sensor for sensing endogenous H2S, [Ru(bpy)2(bpy-DPA)](2+) is first designed and synthesized, showing high ECL efficiency with tri-n-propylamine (TPA) as a coreactant and quenching after reaction with Cu(2+) (forming [Ru(bpy)2(bpy-DPA)Cu](4+)). Then a Nafion membrane is coated on the surface of glassy carbon (GC) electrode and [Ru(bpy)2(bpy-DPA)Cu](4+) is confined onto the Nafion membrane through ion exchange. The resulting [Ru(bpy)2(bpy-DPA)Cu](4+)/Nafion/GC sensor exhibits a low ECL signal. The [Ru(bpy)2(bpy-DPA)Cu](4+)/Nafion/GC sensor demonstrates enhanced ECL signal after reacting with volatile H2S due to the high-affinity binding between sulfur and Cu(2+), returning to [Ru(bpy)2(bpy-DPA)](2+)/Nafion/GC. The changes of ECL signal at the sensor depend linearly on the concentration of Na2S in the range from 0.5 to 10 μM, with a detection limit of 0.25 μM. Moreover, the sensor demonstrates high selectivity, free from interference especially by other nonvolatile thiol-containing species, such as cysteine and glutathione. The basal dialysate level of H2S in the microdialysate from the cortex of adult male Sprague-Dawley rats is determined to be 2.3 ± 0.9 μM (n = 4). This method is reliable and is envisaged to help understand the regulation of H2S in physiological and pathological events. PMID:25574779

  5. Bis(arene) Actinide Sandwich Complexes, (eta6-C6H3R3)2An: Linear or bent?

    SciTech Connect

    Li, Jun; Bursten, Bruce E.

    1999-11-03

    The syntheses of the sandwich complexes ferrocene, (n5-C5H5)2-Fe, in 1951 and uranocene, (n8-C8H8)2U, in 1968 ushered in the modern eras of organotransition metal and organoactinide chemistry, respectively. Ferrocene and uranocene are examples of linear sandwich complexes, that is, those in which the (ring centroid)-M-(ring centroid) angle (denoted 0) is 180 degrees. In the case of (n5-C5H5)2M chemistry, a number of bent (0 < 180 degrees) complexes are known when M is a main-group or rare-earth element. The explanation for the bent structures of these complexes has been the subject of some debate concerning the relative importance of covalent, electrostatic, and steric interactions.

  6. Molecular recognition study of Carbamazepine, antiseizure drug, by p-t-butyl calix(8)arene.

    PubMed

    Meenakshi, C; Jayabal, P; Ramakrishnan, V

    2014-03-25

    The formation of inclusion complex of Carbamazepine, a antiseizure drug molecule, with the supra molecule, p-t-butyl calix(8)arene was studied. p-t-Butyl calix(8)arene was the host molecule and Carbamazepine was the guest molecule. Optical absorption spectral studies were carried out to study the molecular recognition properties of p-t-butyl calix(8)arene with Carbamazepine. The stochiometry of the host-guest complex and the binding constant were determined.

  7. Ferrocene and (arene)ruthenium(II) complexes of the natural anticancer naphthoquinone plumbagin with enhanced efficacy against resistant cancer cells and a genuine mode of action.

    PubMed

    Spoerlein-Guettler, Cornelia; Mahal, Katharina; Schobert, Rainer; Biersack, Bernhard

    2014-09-01

    A series of ferrocene and (arene)ruthenium(II) complexes attached to the naturally occurring anticancer naphthoquinones plumbagin and juglone was tested for efficacy against various cancer cell lines and for alterations in the mode of action. The plumbagin ferrocene and (p-cymene)Ru(II) conjugates 1c and 2a overcame the multi-drug drug resistance of KB-V1/Vbl cervix carcinoma cells and showed IC50 (72 h) values around 1 μM in growth inhibition assays using 3-(4,5-dimethyl-2-yl)-2,5-diphenyltetrazolium bromide (MTT). They were further investigated for their influence on the cell cycle of KB-V1/Vbl and HCT-116 colon carcinoma cells, on the generation of reactive oxygen species (ROS) by the latter cell line, for their substrate character for the P-glycoprotein drug eflux pump via the calcein-AM efflux assays, and for DNA affinity by the electrophoretic mobility shift assay (EMSA). The derivatives 1c and 2a increased the number of dead cancer cells (sub-G0/G1 fraction) in a dose- and time-dependent manner. ROS levels were significantly increased upon treatment with 1c and 2a. These compounds also showed a greater affinity to linear DNA than plumbagin. While plumbagin did not affect calcein-AM transport by P-glycoprotein the derivatives 1c and 2a exhibited a 50% or 80% inhibition of the P-glycoprotein-mediated calcein-AM efflux relative to the clinically established sensitizer verapamil.

  8. Synthesis of (--)-lasubine(I) via a planar chiral [(eta6-arene)Cr(CO)3] complex.

    PubMed

    Ratni, H; Kündig, E P

    1999-12-16

    Key steps of the synthesis of the Lythracaea alkaloid (--)-lasubine(I) are the formation of an enantiopure planar chiral arylaldehyde tricarbonylchromium complex and highly diastereoselective aza-Diels-Alder cycloaddition and intramolecular radical cyclization reactions to afford a quinolizidinone intermediate. Ketone reduction, desilylation, and decomplexation yield the enantiomerically pure product.

  9. Binuclear ruthenium η6-arene complexes with tetradentate N,S-ligands containing the ortho-aminothiophenol motif.

    PubMed

    Acosta-Ramirez, Alberto; Cross, Edward D; McDonald, Robert; Bierenstiel, Matthias

    2014-02-28

    A series of cationic binuclear (η(6)-cymene-Ru)2 complexes with N2S2-ligands were synthesized in 64% to 85% yield by reaction of [Ru(η(6)-cymene)Cl2]2 with bis-S,S'-(ortho-aminothiophenol)-xylenes as BF4(-) and PF6(-) salts. The compounds were studied using NMR, HRMS, UV-vis and IR spectroscopy, EA and inductively coupled plasma (ICP) MS. It was determined that the hinged binuclear Ru complexes were anti and syn diastereomers obtained in 2 : 1 ratio for ortho- and meta-xylylene bridged ligands and in a 1 : 1 ratio for the para-xylylene bridged ligand. An anion effect was found for the presence of NaBF4 with the meta-xylylene bridged system yielding the targeted binuclear Ru complex and a mononuclear Ru complex. This mononuclear S,S'-coordinated η(6)-cymene Ru chloride structure lacked amine-metal coordination and was obtained in a 1 : 3 ratio of anti : syn diastereomers which were insoluble in CH2Cl2 and soluble in DMSO and DMF. X-ray crystallographic analysis was obtained for the N2S2 ligand, 1,2-bis{(2-aminophenyl)thiomethyl}benzene, showing a CS symmetry with amine groups facing outwards with a tilt of 28.95° from the ortho-aminothiophenol pendant ring. The interatomic sulfur-sulfur distance (S-S') is 4.6405 Å within the crystal structure while accommodating a potential metal bite angle from 1.0 Å to 5.9 Å when allowing rotation of the methylene phenyl bond. PMID:24284434

  10. Structural analysis of ruthenium-arene complexes using ion mobility mass spectrometry, collision-induced dissociation, and DFT.

    PubMed

    Czerwinska, Izabella; Far, Johann; Kune, Christopher; Larriba-Andaluz, Carlos; Delaude, Lionel; De Pauw, Edwin

    2016-04-21

    Ion mobility mass spectrometry (IM-MS) and collision-induced dissociation (CID) techniques were used to investigate the influence of the phosphine ligand on the physicochemical properties of [RuCl2(p-cymene)(PCy3)] (), [RuCl2(p-cymene)(PPh3)] (), and [RuCl2(p-cymene)(PTA)] () in the gas phase (PTA is 1,3,5-triaza-7-phosphaadamantane). Electrospray ionization of complexes and led to the corresponding [RuCl(p-cymene)(PR3)](+) ions via the dissociation of a chlorido ligand, whereas RAPTA-C () afforded two molecular ions by in-source oxidation ([Ru(III)Cl2(p-cymene)(PTA)](+)) or protonation ([RuCl2(p-cymene)(PTA+H)](+)). Control experiments showed that the balance between these two ionization paths was strongly influenced by the nature of the solvent used for infusion. Collision cross sections (CCSs) of the four molecular ions accurately reflected the variations of steric bulk inferred from the Tolman steric parameters (θ) of the phosphine ligands. Moreover, DFT calculations combined with a model based on the kinetic theory of gases (the trajectory method of the IMoS software) afforded reliable CCS predictions. The almost two times higher dipole moment of [RuCl2(p-cymene)(PTA+H)](+) (μ = 13.75 D) compared to [Ru(III)Cl2(p-cymene)(PTA)](+) (μ = 7.18 D) was held responsible for increased ion-induced dipole interactions with a polarizable drift gas such as N2. Further experiments with He and CO2 confirmed that increasing the polarizability of the buffer gas improved the separation between the two molecular ions derived from complex . The fragmentation patterns of complexes were determined by CID. The sequence of collision voltages at which 50% of a precursor ion dissociates (V50) recorded for the molecular ions derived from compounds was in good agreement with simple electronic considerations based on the donor strength of the phosphine ligand. Thus, the CCS and V50 parameters used to determine the shape and stability of ionic species in the gas phase are complementary

  11. Structural analysis of ruthenium-arene complexes using ion mobility mass spectrometry, collision-induced dissociation, and DFT.

    PubMed

    Czerwinska, Izabella; Far, Johann; Kune, Christopher; Larriba-Andaluz, Carlos; Delaude, Lionel; De Pauw, Edwin

    2016-04-21

    Ion mobility mass spectrometry (IM-MS) and collision-induced dissociation (CID) techniques were used to investigate the influence of the phosphine ligand on the physicochemical properties of [RuCl2(p-cymene)(PCy3)] (), [RuCl2(p-cymene)(PPh3)] (), and [RuCl2(p-cymene)(PTA)] () in the gas phase (PTA is 1,3,5-triaza-7-phosphaadamantane). Electrospray ionization of complexes and led to the corresponding [RuCl(p-cymene)(PR3)](+) ions via the dissociation of a chlorido ligand, whereas RAPTA-C () afforded two molecular ions by in-source oxidation ([Ru(III)Cl2(p-cymene)(PTA)](+)) or protonation ([RuCl2(p-cymene)(PTA+H)](+)). Control experiments showed that the balance between these two ionization paths was strongly influenced by the nature of the solvent used for infusion. Collision cross sections (CCSs) of the four molecular ions accurately reflected the variations of steric bulk inferred from the Tolman steric parameters (θ) of the phosphine ligands. Moreover, DFT calculations combined with a model based on the kinetic theory of gases (the trajectory method of the IMoS software) afforded reliable CCS predictions. The almost two times higher dipole moment of [RuCl2(p-cymene)(PTA+H)](+) (μ = 13.75 D) compared to [Ru(III)Cl2(p-cymene)(PTA)](+) (μ = 7.18 D) was held responsible for increased ion-induced dipole interactions with a polarizable drift gas such as N2. Further experiments with He and CO2 confirmed that increasing the polarizability of the buffer gas improved the separation between the two molecular ions derived from complex . The fragmentation patterns of complexes were determined by CID. The sequence of collision voltages at which 50% of a precursor ion dissociates (V50) recorded for the molecular ions derived from compounds was in good agreement with simple electronic considerations based on the donor strength of the phosphine ligand. Thus, the CCS and V50 parameters used to determine the shape and stability of ionic species in the gas phase are complementary

  12. 'Non-covalent synthesis' of a chiral host of calix[6]arene and enantiomeric discrimination.

    PubMed

    Fernandes, Sergio Antonio; Nachtigall, Francine F; Lazzarotto, Márcio; Fujiwara, Fred Yukio; Marsaioli, Anita Jocelyne

    2005-05-01

    'Non-covalent synthesis' of novel chiral hosts (calix[6]arene-chiral amine complexes) and its application to enantiomeric discrimination was investigated by (1)H NMR spectroscopy. The topology of a ternary complex was proposed for the calix[6]arene-amine-sulfoxide to rationalize the chiral recognition.

  13. Chemistry of Fe(arene)[sup +] ions with halobenzenes

    SciTech Connect

    Huang, Y.; Ranatunga, D.R.A.; Freiser, B.S. )

    1994-06-01

    The gas-phase ion chemistry between a series of Fe(arene)[sup +] ions and halobenzene and dihalobenzene species was studied. Fe[sup +] in the arene complex acts as a reaction-initiating center to insert oxidatively into the phenyl-X bond (X = Cl, Br, I). The arene ligand then undergoes migratory insertion into the Fe[sup +]-phenyl [sigma] bond. Subsequent hydrogen abstraction from the organic moiety and HX elimination generate Fe(biphenyl)[sup +] ions. This reaction cycle may be repeated up to five times to give Fe(polyphenyl)[sup +]. In contrast, Fe(fluorobenzene)[sup +] shows no reactivity with chlorobenzene, while CH[sub 3] groups on the arene ligand sterically hinder the migratory insertion into the Fe[sup +]-phenyl bond. 29 refs., 1 tab.

  14. Catalytic borylation of SCF₃-functionalized arenes by rhodium(I) boryl complexes: regioselective C-H activation at the ortho-position.

    PubMed

    Kalläne, Sabrina I; Braun, Thomas

    2014-08-25

    An unprecedented reaction pathway for the borylation of SCF3-containing arenes using [Rh(Bpin)(PEt3)3] (pin=pinacolato) is reported. Catalytic processes were developed and the functionalizations proceed under mild reaction conditions. The C-H activations occur with a unique regioselectivity for the position ortho to the SCF3 group, which apparently serves as directing group. Borylated SCF3 compounds can serve as versatile building blocks. PMID:25088814

  15. Photoassisted Synthesis of Complex Molecular Architectures: Dearomatization of Benzenoid Arenes with Aza-o-xylylenes via an Unprecedented [2+4] Reaction Topology.

    PubMed

    Kuznetsov, Dmitry M; Mukhina, Olga A; Kutateladze, Andrei G

    2016-06-01

    A new method was developed for the photoinduced dearomatization of arenes through an intramolecular cycloaddition with aza-o-xylylenes generated by excited-state intramolecular proton transfer (ESIPT) in the readily available photoprecursors. The [2+4] topology of this cycloaddition is unprecedented for photo-dearomatizations of benzenoid aromatic carbocycles. It provides rapid access to novel heterocycles, cyclohexadieno-oxazolidino-quinolinols, as valuable synthons for a broad range of post-photochemical transformations. PMID:27097759

  16. Iridium/N-heterocyclic carbene-catalyzed C–H borylation of arenes by diisopropylaminoborane

    PubMed Central

    Igarashi, Takuya

    2016-01-01

    Summary Catalytic C–H borylation of arenes has been widely used in organic synthesis because it allows the introduction of a versatile boron functionality directly onto simple, unfunctionalized arenes. We report herein the use of diisopropylaminoborane as a boron source in C–H borylation of arenes. An iridium(I) complex with 1,3-dicyclohexylimidazol-2-ylidene is found to efficiently catalyze the borylation of arenes and heteroarenes. The resulting aminoborylated products can be converted to the corresponding boronic acid derivatives simply by treatment with suitable diols or diamines. PMID:27340457

  17. Rational Design of Cesium-Selective Ionophores and Chemosensors: Dihydrocalix[4]arene Crown-6 Ethers

    SciTech Connect

    Sachleben, Richard A.; Bryan, Jeffrey C.; Brown, Gilbert M.; Engle, Nancy L.; Haverlock, Tamara J.; Hay, Benjamin P.; Urvoas, Agathe; Moyer, Bruce A.

    2003-12-15

    Molecular mechanics calculations performed on calix[4]arene crown-6 ethers predict that the 1,3-dihydro derivatives will exhibit greater complementarity for potassium and cesium ions than the parent 1,3-dialkoxy calix crowns. The X-ray crystal structures of 1,3-alt bis-octyloxycalix[4]arene benzocrown-6 ether, dihydrocalix[4]arene benzocrown-6 ether, and the cesium nitrate complex of dihydrocalix[4]arene benzocrown-6 ether were determined. The cesium complex structure corresponds closely to the structure predicted by molecular mechanics. The dihydrocalix[4]arene crown-6 ethers exhibit enhanced cesium selectivity in the extraction of alkali metal salts and provide a platform for a highly sensitive and selective cesium chemosensor.

  18. Metal–Arene Complexes with Indolo[3,2-c]-quinolines: Effects of Ruthenium vs Osmium and Modifications of the Lactam Unit on Intermolecular Interactions, Anticancer Activity, Cell Cycle, and Cellular Accumulation

    PubMed Central

    2013-01-01

    Six novel ruthenium(II)– and osmium(II)–arene complexes with three modified indolo[3,2-c]quinolines have been synthesized in situ starting from 2-aminoindoloquinolines and 2-pyridinecarboxaldehyde in the presence of [M(p-cymene)Cl2]2 (M = Ru, Os) in ethanol. All complexes have been characterized by elemental analysis, spectroscopic techniques (1H, 13C NMR, IR, UV–vis), and ESI mass spectrometry, while four complexes were investigated by X-ray diffraction. The complexes have been tested for antiproliferative activity in vitro in A549 (non-small cell lung), SW480 (colon), and CH1 (ovarian) human cancer cell lines and showed IC50 values between 1.3 and >80 μM. The effects of Ru vs Os and modifications of the lactam unit on intermolecular interactions, antiproliferative activity, and cell cycle are reported. One ruthenium complex and its osmium analogue have been studied for anticancer activity in vivo applied both intraperitoneally and orally against the murine colon carcinoma model CT-26. Interestingly, the osmium(II) complex displayed significant growth-inhibitory activity in contrast to its ruthenium counterpart, providing stimuli for further investigation of this class of compounds as potential antitumor drugs. PMID:23431223

  19. Enhanced catalysis and enantioselective resolution of racemic naproxen methyl ester by lipase encapsulated within iron oxide nanoparticles coated with calix[8]arene valeric acid complexes.

    PubMed

    Sayin, Serkan; Akoz, Enise; Yilmaz, Mustafa

    2014-09-14

    In this study, two types of nanoparticles have been used as additives for the encapsulation of Candida rugosa lipase via the sol-gel method. In one case, the nanoparticles were covalently linked with a new synthesized calix[8]arene octa valeric acid derivative (C[8]-C4-COOH) to produce new calix[8]arene-adorned magnetite nanoparticles (NP-C[8]-C4-COOH), and then NP-C[8]-C4-COOH was used as an additive in the sol-gel encapsulation process. In the other case, iron oxide nanoparticles were directly added into the sol-gel encapsulation process in order to interact electrostatically with both C[8]-C4-COOH and Candida rugosa lipase. The catalytic activities and enantioselectivities of two novel encapsulated lipases (Enc-NP-C[8]-C4-COOH and Enc-C[8]-C4-COOH@Fe3O4) in the hydrolysis reaction of racemic naproxen methyl ester were evaluated. The results showed that the activity and enantioselectivity of the lipase were improved when the lipase was encapsulated in the presence of calixarene-based additives. Indeed, the encapsulated lipases have an excellent rate of enantioselectivity, with E = 371 and 265, respectively, as compared to the free enzyme (E = 137). The lipases encapsulated with C[8]-C4-COOH and iron oxide nanoparticles (Enc-C[8]-C4-COOH@Fe3O4) retained more than 86% of their initial activities after 5 repeated uses and 92% with NP-C[8]-C4-COOH.

  20. Spatially Directional Resorcin[4]arene Cavitand Glycoconjugates for Organic Catalysis.

    PubMed

    Husain, Ali A; Maknenko, Arthur M; Bisht, Kirpal S

    2016-04-25

    The synthesis of novel spatially directional multivalent resorcin[4]arene cavitand glycoconjugates (RCGs) and their ability to catalyze organic reactions is reported. The β-d-glucopyranoside moieties on the upper rim of the "bowl"-shaped resorcin[4]arene cavitand core are capable of multiple hydrogen-bond interactions resulting in a pseudo-cavity, which has been investigated for organic transformations in aqueous media. The RCGs have been demonstrated to catalyze thiazole formation, thiocyanation, copper(I)-catalyzed azide alkyne cycloaddition (CuAAC), and Mannich reactions; they impart stereoselectivity in the three-component Mannich reaction. Thermodynamic values obtained from (1) H diffusion-ordered spectroscopy (DOSY) experiments suggest that the upper saccharide cavity of the RCG and not the resorcin[4]arene cavity is the site of the complexation event.

  1. Molecular Recognition of Natural Products by Resorc[4]arene Receptors.

    PubMed

    D'Acquarica, Ilaria; Ghirga, Francesca; Quaglio, Deborah; Cerreto, Antonella; Ingallina, Cinzia; Tafi, Andrea; Botta, Bruno

    2016-01-01

    This review is aimed at providing an overview of the up-to-now published literature on resorc[4]arene macrocycles exploited as artificial receptors for the molecular recognition of some classes of natural products. A concise illustration of the main synthetic strategies developed to afford the resorc[4]arene scaffold is followed by a report on the principles of the gas-phase investigation of recognition phenomena by mass spectrometry (MS). Emphasis is placed on gas-phase studies of diastereoisomeric complexes generated inside a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer by resorc[4]arene receptors towards a series of natural products, namely amino acids, amphetamine, ethanolamine neurotransmitters, dipeptides, vinca alkaloids and nucleosides. The literature outcomes discussed here, taken largely from our own revisited work, have been completed by references to other studies, in order to draw a broader picture of this rapidly evolving field of research. PMID:26654589

  2. Heteroatom-free arene-cobalt and arene-iron catalysts for hydrogenations.

    PubMed

    Gärtner, Dominik; Welther, Alice; Rad, Babak Rezaei; Wolf, Robert; Jacobi von Wangelin, Axel

    2014-04-01

    75 years after the discovery of hydroformylation, cobalt catalysts are now undergoing a renaissance in hydrogenation reactions. We have evaluated arene metalates in which the low-valent metal species is--conceptually different from heteroatom-based ligands--stabilized by π coordination to hydrocarbons. Potassium bis(anthracene)cobaltate 1 and -ferrate 2 can be viewed as synthetic precursors of quasi-"naked" anionic metal species; their aggregation is effectively impeded by (labile) coordination to the various π acceptors present in the hydrogenation reactions of unsaturated molecules (alkenes, arenes, carbonyl compounds). Kinetic studies, NMR spectroscopy, and poisoning studies of alkene hydrogenations support the formation of a homogeneous catalyst derived from 1 which is stabilized by the coordination of alkenes. This catalyst concept complements the use of complexes with heteroatom donor ligands for reductive processes. PMID:24616276

  3. Solvation structure around ruthenium(II) tris(bipyridine) in lithium halide solutions

    PubMed Central

    Josefsson, Ida; Eriksson, Susanna K.; Rensmo, Håkan; Odelius, Michael

    2016-01-01

    The solvation of the ruthenium(II) tris(bipyridine) ion ([Ru(bpy)3]2+) is investigated with molecular dynamics simulations of lithium halide solutions in polar solvents. The anion distribution around the [Ru(bpy)3]2+ complex exhibits a strong solvent dependence. In aqueous solution, the iodide ion forms a solvent shared complex with [Ru(bpy)3]2+, but not in the other solvents. Between Cl– and [Ru(bpy)3]2+, the strong hydration of the chloride ion results in a solvent separated complex where more than one solvent molecule separates the anion from the metal center. Hence, tailored solvation properties in electrolytes is a route to influence ion-ion interactions and related electron transfer processes. PMID:26798838

  4. Spontaneous reduction and C-H borylation of arenes mediated by uranium(III) disproportionation.

    PubMed

    Arnold, Polly L; Mansell, Stephen M; Maron, Laurent; McKay, David

    2012-07-15

    Transition-metal-arene complexes such as bis(benzene)chromium Cr(η(6)-C(6)H(6))(2) are historically important to d-orbital bonding theory and have modern importance in organic synthesis, catalysis and organic spintronics. In investigations of f-block chemistry, however, arenes are invariably used as solvents rather than ligands. Here, we show that simple uranium complexes UX(3) (X = aryloxide, amide) spontaneously disproportionate, transferring an electron and X-ligand, allowing the resulting UX(2) to bind and reduce arenes, forming inverse sandwich molecules [X(2)U(µ-η(6):η(6)-arene)UX(2)] and a UX(4) by-product. Calculations and kinetic studies suggest a 'cooperative small-molecule activation' mechanism involving spontaneous arene reduction as an X-ligand is transferred. These mild reaction conditions allow functionalized arenes such as arylsilanes to be incorporated. The bulky UX(3) are also inert to reagents such as boranes that would react with the traditional harsh reaction conditions, allowing the development of a new in situ arene C-H bond functionalization methodology converting C-H to C-B bonds.

  5. Spontaneous reduction and C-H borylation of arenes mediated by uranium(III) disproportionation

    NASA Astrophysics Data System (ADS)

    Arnold, Polly L.; Mansell, Stephen M.; Maron, Laurent; McKay, David

    2012-08-01

    Transition-metal-arene complexes such as bis(benzene)chromium Cr(η6-C6H6)2 are historically important to d-orbital bonding theory and have modern importance in organic synthesis, catalysis and organic spintronics. In investigations of f-block chemistry, however, arenes are invariably used as solvents rather than ligands. Here, we show that simple uranium complexes UX3 (X = aryloxide, amide) spontaneously disproportionate, transferring an electron and X-ligand, allowing the resulting UX2 to bind and reduce arenes, forming inverse sandwich molecules [X2U(µ-η6:η6-arene)UX2] and a UX4 by-product. Calculations and kinetic studies suggest a ‘cooperative small-molecule activation’ mechanism involving spontaneous arene reduction as an X-ligand is transferred. These mild reaction conditions allow functionalized arenes such as arylsilanes to be incorporated. The bulky UX3 are also inert to reagents such as boranes that would react with the traditional harsh reaction conditions, allowing the development of a new in situ arene C-H bond functionalization methodology converting C-H to C-B bonds.

  6. Fluorescence and piezoresistive cantilever sensing of trinitrotoluene by an upper-rim tetrabenzimidazole conjugate of calix[4]arene and delineation of the features of the complex by molecular dynamics.

    PubMed

    Kandpal, Manoj; Bandela, Anil Kumar; Hinge, Vijaya Kumar; Rao, V Ramgopal; Rao, Chebrolu Pulla

    2013-12-26

    A new benzimidazole-functionalized calix[4]arene receptor (R) was synthesized and characterized. The receptor R shows better selectivity toward trinitrotoluene (TNT) compared to the other nitro explosives in solution, which also retains its effectiveness for solid-phase detection. The chemical interactions of the molecule with different nitro explosive analytes were studied by fluorescence spectroscopy and by a molecular dynamics approach. The molecular dynamics studies show a 1:3 complex between R and TNT, and hence high sensitivity was imparted by fluorescence studies. The detection of explosive vapors in ambient conditions was tested by using a sensitive coating layer of R on an SU-8/CB-based piezoresistive cantilever surface. The developed device showed large sensitivity toward TNT compared to cyclotrimethylenetrinitramine (RDX) and pentaerythritol tetranitrate (PETN) in the solid state at their respective vapor pressures at room temperature. The detection sensitivity of the device was estimated to be 35 mV for TNT at ambient conditions. Moreover, the sensor does not show a response when exposed to humidity. These results demonstrate that R can be used as one of the coating materials for a cantilever for the detection of TNT using piezoresistivity measurement. R can also detect the explosives in solution with high sensitivity and selectivity by fluorescence spectroscopy.

  7. Design and synthesis of DNA-tethered ruthenium complexes that self-assemble into linear arrays.

    PubMed

    Stewart, Kristen M; McLaughlin, Larry W

    2003-12-01

    Ruthenium(II) bis(terpyridine) complexes have been prepared with two triethylene glycol linkers to which DNA sequences have been attached; hybridization at various complex ratios results in linear arrays of varying lengths.

  8. Theoretical Modeling of the Magnetic Behavior of Thiacalix[4]arene Tetranuclear Mn(II)2Gd(III)2 and Co(II)2Eu(III)2 Complexes.

    PubMed

    Aldoshin, Sergey M; Sanina, Nataliya A; Palii, Andrew V; Tsukerblat, Boris S

    2016-04-01

    In view of a wide perspective of 3d-4f complexes in single-molecule magnetism, here we propose an explanation of the magnetic behavior of the two thiacalix[4]arene tetranuclear heterometallic complexes Mn(II)2Gd(III)2 and Co(II)2Eu(III)2. The energy pattern of the Mn(II)2Gd(III)2 complex evaluated in the framework of the isotropic exchange model exhibits a rotational band of the low-lying spin excitations within which the Landé intervals are affected by the biquadratic spin-spin interactions. The nonmonotonic temperature dependence of the χT product observed for the Mn(II)2Gd(III)2 complex is attributed to the competitive influence of the ferromagnetic Mn-Gd and antiferromagnetic Mn-Mn exchange interactions, the latter being stronger (J(Mn, Mn) = -1.6 cm(-1), Js(Mn, Gd) = 0.8 cm(-1), g = 1.97). The model for the Co(II)2Eu(III)2 complex includes uniaxial anisotropy of the seven-coordinate Co(II) ions and an isotropic exchange interaction in the Co(II)2 pair, while the Eu(III) ions are diamagnetic in their ground states. Best-fit analysis of χT versus T showed that the anisotropic contribution (arising from a large zero-field splitting in Co(II) ions) dominates (weak-exchange limit) in the Co(II)2Eu(III)2 complex (D = 20.5 cm(-1), J = -0.4 cm(-1), gCo = 2.22). This complex is concluded to exhibit an easy plane of magnetization (arising from the Co(II) pair). It is shown that the low-lying part of the spectrum can be described by a highly anisotropic effective spin-(1)/2 Hamiltonian that is deduced for the Co(II)2 pair in the weak-exchange limit.

  9. Structural characterization and some coordinational aspects of tetrathiacalix[4]arenes functionalized by hydrazide groups

    NASA Astrophysics Data System (ADS)

    Podyachev, Sergey N.; Gubaidullin, Aidar T.; Syakaev, Victor V.; Sudakova, Svetlana N.; Masliy, Aleksey N.; Saifina, Alina F.; Burmakina, Nadezda Е.; Kuznetsov, Andrey M.; Shagidullin, Roald R.; Avvakumova, Ludmila V.; Konovalov, Alexander I.

    2010-04-01

    The structural peculiarities of tetrathiacalix[4]arenes with acetylhydrazide substitutes in cone and 1,3 -alternate conformations have been determined by means of X-ray analysis, IR and NMR spectroscopy. The structural and molecular modeling data were used in the interpretation of binding properties of calix[4]arene tetrahydrazides. The quantum-chemical calculations at the DFT level using the PBE exchange-correlation functional were performed for the complexation of 1,3 -alternate conformer of tetrathiacalix[4]arene with Ag + ion. It was shown that the removal of tert-butyl groups from tert-butyltetrathiacalix[4]arene platform facilitates a bis-ligand coordination of the metal ion and leads to a remarkable increase of Ag + extraction efficiency.

  10. Solvent assisted formation of ruthenium(III) and ruthenium(II) hydrazone complexes in one-pot with potential in vitro cytotoxicity and enhanced LDH, NO and ROS release.

    PubMed

    Jayanthi, Eswaran; Kalaiselvi, Sivalingam; Padma, Viswanatha Vijaya; Bhuvanesh, Nattamai S P; Dharmaraj, Nallasamy

    2016-01-28

    A set each of new bivalent and trivalent ruthenium complexes, [Ru(III)(HL)Cl2(EPh3)2] and [Ru(II)(L)(CO)(EPh3)2] (E = P (complexes and ) or As (complexes and )) were synthesised from the reactions of [Ru(III)Cl3(EPh3)3] with 2-hydroxynaphthaldehyde benzoic acid hydrazone (H2L) in methanol-chloroform and characterized by elemental analysis, spectral data and XRD study. A suitable mechanism to account for the formation of bivalent ruthenium carbonyl complexes from the corresponding trivalent precursors is provided by considering the role of added base in the reaction. Interaction of complexes with CT-DNA/bovine serum albumin was analysed with absorption and emission spectral titration studies. In vitro cytotoxic potential of the above ruthenium hydrazone complexes assayed against the A549 cell line revealed a significant growth inhibition. The test complexes added in IC50 concentration into the cell culture medium enhanced the release of lactate dehydrogenase, NO and reactive oxygen species in comparison with the control. Cell death induced by the complexes was studied using a propidium iodide staining assay and showed noticeable changes in the cell morphology which resembled apoptosis.

  11. Solvent assisted formation of ruthenium(III) and ruthenium(II) hydrazone complexes in one-pot with potential in vitro cytotoxicity and enhanced LDH, NO and ROS release.

    PubMed

    Jayanthi, Eswaran; Kalaiselvi, Sivalingam; Padma, Viswanatha Vijaya; Bhuvanesh, Nattamai S P; Dharmaraj, Nallasamy

    2016-01-28

    A set each of new bivalent and trivalent ruthenium complexes, [Ru(III)(HL)Cl2(EPh3)2] and [Ru(II)(L)(CO)(EPh3)2] (E = P (complexes and ) or As (complexes and )) were synthesised from the reactions of [Ru(III)Cl3(EPh3)3] with 2-hydroxynaphthaldehyde benzoic acid hydrazone (H2L) in methanol-chloroform and characterized by elemental analysis, spectral data and XRD study. A suitable mechanism to account for the formation of bivalent ruthenium carbonyl complexes from the corresponding trivalent precursors is provided by considering the role of added base in the reaction. Interaction of complexes with CT-DNA/bovine serum albumin was analysed with absorption and emission spectral titration studies. In vitro cytotoxic potential of the above ruthenium hydrazone complexes assayed against the A549 cell line revealed a significant growth inhibition. The test complexes added in IC50 concentration into the cell culture medium enhanced the release of lactate dehydrogenase, NO and reactive oxygen species in comparison with the control. Cell death induced by the complexes was studied using a propidium iodide staining assay and showed noticeable changes in the cell morphology which resembled apoptosis. PMID:26699435

  12. Synthesis of a ruthenium(II) bipyridyl complex coordinated by a functionalized Schiff base ligand: Characterization, spectroscopic and isothermal titration calorimetry measurements of M 2+ binding and sensing (M 2+ = Ca 2+, Mg 2+)

    NASA Astrophysics Data System (ADS)

    Dixit, Namrata; Mishra, Lallan; Mustafi, Sourajit M.; Chary, Kandala V. R.; Houjou, Hirohiko

    2009-07-01

    Bis-[methylsalicylidine-4'benzoic acid]-ethylene (LH 2) complexed with cis-Ru(bpy) 2Cl 2·2H 2O provides a complex of composition [Ru(bpy) 2L]·2NH 4PF 6 ( 1), which has been characterized spectroscopically. Its binding behaviour towards Mg 2+ and Ca 2+ ions is monitored using 1H NMR titration, isothermal titration calorimetry (ITC) and luminescence microscopy. The luminescent ruthenium complex binds Ca 2+ in a more selective manner as compared to Mg 2+.

  13. Synthesis of a ruthenium(II) bipyridyl complex coordinated by a functionalized Schiff base ligand: characterization, spectroscopic and isothermal titration calorimetry measurements of M2+ binding and sensing (M2+=Ca2+, Mg2+).

    PubMed

    Dixit, Namrata; Mishra, Lallan; Mustafi, Sourajit M; Chary, Kandala V R; Houjou, Hirohiko

    2009-07-01

    Bis-[methylsalicylidine-4'benzoic acid]-ethylene (LH2) complexed with cis-Ru(bpy)2Cl(2).2H2O provides a complex of composition [Ru(bpy)2L].2NH4PF6 (1), which has been characterized spectroscopically. Its binding behaviour towards Mg2+ and Ca2+ ions is monitored using 1H NMR titration, isothermal titration calorimetry (ITC) and luminescence microscopy. The luminescent ruthenium complex binds Ca2+ in a more selective manner as compared to Mg2+.

  14. Photocyclizable resorcin[4]arene dimers.

    PubMed

    Schäfer, Christian; Strübe, Frank; Bringmann, Sebastian; Mattay, Jochen

    2008-12-01

    The synthesis of covalently linked dimers, containing two resorcin[4]arene moieties connected over two 9,10-functionalized anthracene units, is reported. Besides the synthetic route, which involves for example the formation of anthracene-9,10-dialkanols ( and ), and characterization of the compounds, the photochemical properties, introduced through the anthracene groups, were investigated by means of UV/VIS spectroscopy. Both resorcin[4]arene dimers ( and ) were able to undergo an intramolecular [4+4] cycloaddition, therefore changing the size of the inner cavity. Unfortunately, the back reaction, which was expected to take place on irradiation below 300 nm or upon heating, was not observed yet and will be the focus of our future work.

  15. Gas-phase and solution studies of three resorcin[4]arene derivatives using electrospray time-of-flight mass spectrometry.

    PubMed

    Reynolds, James C; Chew, Mei Q; Martin, Helen J; Stubbs, Emma C; Waters, Marguerite A; Crotty, Sarah C; Silvestre-Gonzalez, Vanessa; Chan, Yohan; Thomas, C L Paul; Page, Philip C Bulman; Creaser, Colin S; Heaney, Harry

    2013-01-01

    Electrospray ionisation mass spectrometry (ESI-MS) has been used to study the relative gas-phase proton and alkali metal (Li, Na, K and Cs) binding affinities of three different resorcin[4]arenes using the kinetic method. Collision-induced dissociation (CID) was used to study the fragmentation of resorcin[4]arene heterodimer sandwich complexes, allowing the relative binding affinity order to be established. All the alkali metal cations have the same gas-phase binding affinity order with the resorcin[4]arene host molecules. At collision energies of > or = 13eV, one of the [resorcin[4]arene+Metal]+, (Metal = Li, Na, K) ions fragmented through break-up of the resorcin[4]arene, whilst the other host resorcin[4]arene remained intact, causing an apparent change in binding affinity at high collision energy. This effect was not observed with caesium, since all complex ions dissociated readily under CID by displacement of the caesium cation. The binding affinity for the protonated resorcin[4]arenes was found to be different from the alkali metal cation binding affinity because of the higher proton affinity of the nitrogen-containing resorcin[4]arenes. It is shown that resorcin[4]arenes containing an oxazine ring can be converted into a ring-opened derivative via an Eschweiler-CLarke reaction in the presence of formic acid. A second ring-opening process also occurs, including a hydrolysis reaction that results in apparent Losses of 12 mass units from the intact resorcin[4]arene. Both these reactions occur in solution before mass spectrometric investigation and cannot be achieved by CID. This observation was confirmed by inducing the Eschweiter-CLarke reaction in a model benzoxazine compound.

  16. Arene oxidation with malonoyl peroxides.

    PubMed

    Dragan, Andrei; Kubczyk, Tomasz M; Rowley, Julian H; Sproules, Stephen; Tomkinson, Nicholas C O

    2015-06-01

    Malonoyl peroxide 7, prepared in a single step from the commercially available diacid, is an effective reagent for the oxidation of aromatics. Reaction of an arene with peroxide 7 at room temperature leads to the corresponding protected phenol which can be unmasked by aminolysis. An ionic mechanism consistent with the experimental findings and supported by isotopic labeling, Hammett analysis, EPR investigations, and reactivity profile studies is proposed. PMID:25966313

  17. Homo- and Heterobimetallic Ruthenium(II) and Osmium(II) Complexes Based on a Pyrene-Biimidazolate Spacer as Efficient DNA-Binding Probes in the Near-Infrared Domain.

    PubMed

    Mardanya, Sourav; Karmakar, Srikanta; Mondal, Debiprasad; Baitalik, Sujoy

    2016-04-01

    We report in this work a new family of homo- and heterobimetallic complexes of the type [(bpy)2M(Py-Biimz)M'(II)(bpy)2](2+) (M = M' = Ru(II) or Os(II); M = Ru(II) and M' = Os(II)) derived from a pyrenyl-biimidazole-based bridge, 2-imidazolylpyreno[4,5-d]imidazole (Py-BiimzH2). The homobimetallic Ru(II) and Os(II) complexes were found to crystallize in monoclinic form with space group P21/n. All the complexes exhibit strong absorptions throughout the entire UV-vis region and also exhibit luminescence at room temperature. For osmium-containing complexes (2 and 3) both the absorption and emission band stretched up to the NIR region and thus afford more biofriendly conditions for probable applications in infrared imaging and phototherapeutic studies. Detailed luminescence studies indicate that the emission originates from the respective (3)MLCT excited state mainly centered in the [M(bpy)2](2+) moiety of the complexes and is only slightly affected by the pyrene moiety. The bimetallic complexes show two successive one-electron reversible metal-centered oxidations in the positive potential window and several reduction processes in the negative potential window. An efficient intramolecular electronic energy transfer is found to occur from the Ru center to the Os-based component in the heterometallic dyad. The binding studies of the complexes with DNA were thoroughly studied through different spectroscopic techniques such as UV-vis absorption, steady-state and time-resolved emission, circular dichroism, and relative DNA binding study using ethidium bromide. The intercalative mode of binding was suggested to be operative in all cases. Finally, computational studies employing DFT and TD-DFT were also carried out to interpret the experimentally observed absorption and emission bands of the complexes. PMID:27011117

  18. A SAR study of novel antiproliferative ruthenium and osmium complexes with quinoxalinone ligands in human cancer cell lines.

    PubMed

    Ginzinger, Werner; Mühlgassner, Gerhard; Arion, Vladimir B; Jakupec, Michael A; Roller, Alexander; Galanski, Markus; Reithofer, Michael; Berger, Walter; Keppler, Bernhard K

    2012-04-12

    A series of ruthenium(II) arene complexes with 3-(1H-benzimidazol-2-yl)-1H-quinoxalin-2-one, bearing pharmacophoric groups of known protein kinase inhibitors, and related benzoxazole and benzothiazole derivatives have been synthesized. In addition, the corresponding osmium complexes of the unsubstituted ligands have also been prepared. The compounds have been characterized by NMR, UV-vis, and IR spectroscopy, ESI mass spectrometry, elemental analysis, and by X-ray crystallography. Antiproliferative activity in three human cancer cell lines (A549, CH1, SW480) was determined by MTT assays, yielding IC(50) values of 6-60 μM for three unsubstituted metal-free ligands, whereas values for the metal complexes vary in a broad range from 0.3 to 140 μM. Complexation with osmium of quinoxalinone derivatives with benzimidazole or benzothiazole results in a more consistent increase in cytotoxicity than complexation with ruthenium. For selected compounds, the capacity to induce apoptosis was confirmed by fluorescence microscopy and flow-cytometric analysis, whereas cell cycle effects are only moderate.

  19. SO2-Binding Properties of Cationic η6,η1-NCN-Pincer Arene Ruthenium Platinum Complexes: Spectroscopic and Theoretical Studies

    SciTech Connect

    Bonnet, Sylvestre A.; Van Lenthe, Joop H.; van Dam, Hubertus JJ; van Koten, Gerard; Klein Gebbink, Robertus J M

    2011-03-01

    The SO2-binding properties of a series of η6,η1-NCN-pincer ruthenium platinum complexes have been studied by both UV-visible spectroscopy, and theoretical calculations. When an electronwithdrawing [Ru(C5R5)]+ fragment (R = H or Me) is η6-coordinated to the phenyl ring of the NCNpincer platinum fragment (cf. [2]+ and [3]+, see scheme 1), the characteristic orange coloration (pointing to η1- SO2 binding to Pt) of a solution of the parent NCN-pincer platinum complex 1 in dichloromethane upon SO2-bubbling is not observed. However, when the ruthenium center is η6- coordinated to a phenyl substituent linked in para-position to the carbon-to-platinum bond, i.e. complex [4]+, the SO2-binding property of the NCN-platinum center seems to be retained, as bubbling SO2 into a solution of the latter complex produces the characteristic orange color. We performed theoretical calculations at the MP2 level of approximation and TD-DFT studies, which enabled us to interpret the absence of color change in the case of [2]+ as an absence of coordination of SO2 to platinum. We analyze this absence or weaker SO2-coordination in dichloromethane to be a consequence of the relative electron-poorness of the platinum center in the respective η6- ruthenium coordinated NCN-pincer platinum complexes, that leads to a lower binding energy and an elongated calculated Pt-S bond distance. We also discuss the effects of electrostatic interactions in these cationic systems, which also seems to play a destabilizing role for complex [2(SO2)]+.

  20. Topoisomerase IIα poisoning and DNA double-strand breaking by chiral ruthenium(ii) complexes containing 2-furanyl-imidazo[4,5-f][1,10]phenanthroline derivatives.

    PubMed

    Qian, Chen; Wu, Jingheng; Ji, Liangnian; Chao, Hui

    2016-06-28

    Four chiral Ru(ii) complexes bearing furan ligands, Δ/Λ-[Ru(bpy)2(pocl)](2+) () and Δ/Λ-[Ru(bpy)2(poi)](2+) () (bpy = 2,2'-bipyridine, pocl = 2-(5-chlorofuran-2-yl)imidazo[4,5-f][1,10]phenanthroline, poi = 2-(5-5-iodofuran-2-yl)imidazo[4,5-f][1,10]phenanthroline), were synthesized and characterized. These Ru(ii) complexes showed antitumor activities against HeLa, A549, HepG2, HL-60 and K562 tumor cell lines, especially the HL-60 tumor cell line. Moreover, was more active than other complexes accounting for the different cellular uptakes. In addition, could accumulate in the nucleus of HL-60 cells, suggesting that nucleic acids were the cellular target of . Topoisomerase inhibition tests in vitro and in living cells confirmed that the four complexes acted as efficient topoisomerase IIα poisons, DNA double-strand breaks had also been observed from neutral single cell gel electrophoresis (comet assay). inhibited the growth of HL-60 cells through the induction of apoptotic cell death, as evidenced by the Alexa Fluor® 488 annexin V staining assays. The results demonstrated that acted as a topoisomerase IIα poison and caused DNA double-strand damage that could lead to apoptosis. PMID:27226117

  1. Preparation and characterization of ruthenium(II) monophosphaferrocene complexes. Reactivity, dynamic solution behavior, and X-ray structure of [RuH(2)(eta(2)-H(2))(PCy(3))2(2-phenyl-3,4-dimethylphosphaferrocene)].

    PubMed

    Toner, A J; Donnadieu, B; Sabo-Etienne, S; Chaudret, B; Sava, X; Mathey, F; Le Floch, P

    2001-06-18

    The bis(dihydrogen) complex RuH(2)(H(2))(2)(PCy(3))(2) (1) reacts with 2-phenyl-3,4-dimethylphosphaferrocene (L(1)) to give RuH(2)(H(2))(PCy(3))(2)(L(1)) (2). This dihydride-dihydrogen complex has been characterized by X-ray crystallography and variable-temperature (1)H and (31)P NMR spectroscopy. The exchange between the dihydrogen ligand and the two hydrides is characterized by a DeltaG() of 46.2 kJ/mol at 263 K. H/D exchange is readily observed when heating a C(7)D(8) solution of 2 (J(H-D) = 30 Hz). The H(2) ligand in 2 can be displaced by ethylene or carbon monoxide leading to the corresponding ethylene or carbonyl complexes. The reaction of 1 with 2 equiv of 3,4-dimethylphosphaferrocene (L(2)) yields the dihydride complex RuH(2)(PCy(3))(2)(L(2))(2) (5). PMID:11399170

  2. Metal-to-Ligand Charge-Transfer Emissions of Ruthenium(II) Pentaammine Complexes with Monodentate Aromatic Acceptor Ligands and Distortion Patterns of their Lowest Energy Triplet Excited States.

    PubMed

    Tsai, Chia Nung; Mazumder, Shivnath; Zhang, Xiu Zhu; Schlegel, H Bernhard; Chen, Yuan Jang; Endicott, John F

    2015-09-01

    This is the first report of the 77 K triplet metal-to-ligand charge-transfer ((3)MLCT) emission spectra of pentaammine-MDA-ruthenium(II) ([Ru(NH3)5(MDA)](2+)) complexes, where MDA is a monodentate aromatic ligand. The emission spectra of these complexes and of the related trans-[Ru(NH3)4(MDA) (MDA')](2+) complexes are closely related, and their emission intensities are very weak. Density functional theory (DFT) calculations indicate that the energies of the lowest (3)MLCT excited states of Ru-MDA complexes are either similar to or lower than those of the lowest energy metal-centered excited states ((3)MC(X(Y))), that the barrier to internal conversion at 77 K is large compared to kBT, and that the (3)MC(X(Y)) excited states are weakly bound. The [Ru(NH3)5py](2+) complex is an exception to the general pattern: emission has been observed for the [Ru(ND3)5(d5-py)](2+) complex, but its lifetime is apparently very short. DFT modeling indicates that the excited state distortions of the different (3)MC excited states are very large and are in both Ru-ligand bonds along a single Cartesian axis for each different (3)MC excited state, nominally resulting in (3)MC(X(Y)), (3)MC((X)Y), and (3)MC(Z) lowest energy metal-centered states. The (3)MC(X(Y)) and (3)MC((X)Y) states appear to be the pseudo-Jahn-Teller distorted components of a (3)MC((XY)) state. The (3)MC(X(Y)) states are distorted up to 0.5 Å in each H3N-Ru-NH3 bond along a single Cartesian axis in the pentaammine and trans-tetraammine complexes, whereas the (3)MC(Z) states are found to be dissociative. DFT modeling of the (3)MLCT excited state of [Ru(NH3)5(py)](2+) indicates that the Ru center has a spin density of 1.24 at the (3)MLCT energy minimum and that the (3)MLCT → (3)MC(Z) crossing is smooth with a very small barrier (<0.5 kcal/mol) along the D3N-Ru-py distortion coordinate, implying strong (3)MLCT/(3)MC excited state configurational mixing. Furthermore, the DFT modeling indicates that the long

  3. Conformational features and recognition properties of a conformationally blocked calix[7]arene derivative.

    PubMed

    Gaeta, Carmine; Talotta, Carmen; Farina, Francesco; Campi, Gaetano; Camalli, Mercedes; Neri, Placido

    2012-01-23

    The shaping of a calix[7]arene macrocycle into cone-like structure 3, through exhaustive alkylation of doubly bridged calix[7]arene derivative 2 with bulky groups, has been investigated. Conformational details about the structure adopted by calix[7]arene derivative 3 in solution have been obtained by using chemical shift surface maps, as previously reported by our group. Thus, chemical shift contour plots indicated that 3 adopted a cone-shaped structure in solution analogous to that adopted by the known p-tert-butylcalix[7]arene heptacarboxylic acid derivative 4. Interestingly, the X-ray structure of derivative 3 showed a high degree of similarity to the theoretical structure, which confirmed the validity of the contour plots method. The preorganized calix[7]arene host 3 showed interesting recognition abilities toward both organic and alkali cations. In fact, an unprecedented endo-cavity complexation of linear and branched alkyl ammonium cations with a larger calix[7]arene host was evidenced. A comparable affinity for branched tBuNH(3)(+) and linear nBuNH(3)(+) guests was observed.

  4. Bis(arene) actinide sandwich complexes, ({eta}{sup 6}-C{sub 6}H{sub 3}R{sub 3}){sub 2}An: Linear or bent?

    SciTech Connect

    Li, J.; Bursten, B.E.

    1999-11-03

    The syntheses of the sandwich complexes ferrocene, ({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}-Fe, in 1951 and uranocene, ({eta}{sup 8}-C{sub 8}H{sub 8}){sub 2}U, in 1968 ushered in the modern eras of organotransition metal and organoactinide chemistry, respectively. Ferrocene and uranocene are examples of linear sandwich complexes, that is, those in which the (ring centroid)-M-(ring centroid) angle (denoted {theta}) is 180{degree}. In the case of ({eta}{sup 5}-C{sub 5}H{sub 5}){sub 2}M chemistry, a number of bent ({theta} < 180{degree}) complexes are known when M is a main-group or rare-earth element. The explanation for the bent structures of these complexes has been the subject of some debate concerning the relative importance of covalent, electrostatic, and steric interactions. The authors report optimized geometries of Bz{sub 2}An (An = Th-Am) and ({eta}{sup 6}-C{sub 6}H{sub 3}R{sub 3}){sub 2}An (An = Th, U, Pu; R = Me, {sup t}Bu) obtained by using local density approximation (LDA) and Perdew-Wang (PW91) gradient-corrected relativistic density functional theory (DFT) methods. These DFT methods are found to be able to reproduce the experimental geometries and vibrational frequencies of organoactinide complexes with satisfactory accuracy. The (TTB){sub 2}An calculations that are reported here are, to date, the largest full geometry optimizations to be carried out on an actinide system.

  5. Vectorial property dependence in bis {4'-(n-pyridyl)-2,2':6',2"-terpyridine}iron(II) and ruthenium(II) complexes with n = 2, 3 and 4.

    PubMed

    Beves, Jonathon E; Dunphy, Emma L; Constable, Edwin C; Housecroft, Catherine E; Kepert, Cameron J; Neuburger, Markus; Price, David J; Schaffner, Silvia

    2008-01-21

    A comparative structural and spectroscopic investigation of the complexes [M(1)2]2+, [M(2)2]2+ and [M(3)2]2+ in which M = Fe or Ru, and ligands 1, 2 and 3 are 4'-(2-pyridyl)-, 4'-(3-pyridyl)- and 4'-(4-pyridyl)-2,2':6',2"-terpyridine, respectively, is reported. The complexes [Ru(1)2]2+, [Ru(2)2]2+ and [Ru(3)2]2+ undergo mono- and bis-N-methylation. The consequences of methylation on the absorption spectra and electrochemical properties are discussed; the solid-state structure of the bis(N-methylated) derivative of [Ru(2)2][PF6]2 is presented.

  6. Density functional theory study of oxygen-atom insertion into metal-methyl bonds of iron(II), ruthenium(II), and osmium(II) complexes: study of metal-mediated C-O bond formation.

    PubMed

    Pardue, Daniel B; Mei, Jiajun; Cundari, Thomas R; Gunnoe, T Brent

    2014-03-17

    Metal-mediated C-O bond formation is a key step in hydrocarbon oxygenation catalytic cycles; however, few examples of this reaction have been reported for low-oxidation-state complexes. Oxygen insertion into a metal-carbon bond of Cp*M(CO)(OPy)R (Cp* = η(5)-pentamethylcyclopentadienyl; R = Me, Ph; OPy = pyridine-N-oxide; M = Fe, Ru, Os) was analyzed via density functional theory calculations. Oxygen-atom insertions through a concerted single-step organometallic Baeyer-Villiger pathway and a two-step pathway via a metal-oxo intermediate were studied; calculations predict that the former pathway was lower in energy. The results indicated that functionalization of M-R to M-OR (R = Me, Ph) is plausible using iron(II) complexes. Starting from Cp*Fe(CO)(OPy)Ph, the intermediate Fe-oxo showed oxyl character and, thus, is best considered an Fe(III)O(•-) complex. Oxidation of the π-acid ancillary ligand CO was facile. Substitutions of CO with dimethylamide and NH3 were calculated to lower the activation barrier by ∼1-2 kcal/mol for formation of the Fe(III)O(•-) intermediate, whereas a chloride ligand raised the activation barrier to 26 kcal/mol from 22.9 kcal/mol. PMID:24571202

  7. Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions.

    PubMed

    Deacon, Glen B; Junk, Peter C; Moxey, Graeme J; Ruhlandt-Senge, Karin; St Prix, Courtney; Zuniga, Maria F

    2009-01-01

    Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200-250 degrees C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)(2)(Odpp)(3)](+) cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)(4)] (Ae = Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)(4)] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba(2)(Odpp)(4)] with [Mg(Odpp)(2)(thf)(2)] in toluene afforded [Ba(2)(Odpp)(3)][Mg(Odpp)(3)(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)(2)(Odpp)(3)][Ln(Odpp)(4)] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive pi-Ph-metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species.

  8. Interactions of the "piano-stool" [ruthenium(II)(η(6) -arene)(quinolone)Cl](+) complexes with water; DFT computational study.

    PubMed

    Zábojníková, Tereza; Cajzl, Radim; Kljun, Jakob; Chval, Zdeněk; Turel, Iztok; Burda, Jaroslav V

    2016-07-15

    Full optimizations of stationary points along the reaction coordinate for the hydration of several quinolone Ru(II) half-sandwich complexes were performed in water environment using the B3PW91/6-31+G(d)/PCM/UAKS method. The role of diffuse functions (especially on oxygen) was found crucial for correct geometries along the reaction coordinate. Single-point (SP) calculations were performed at the B3LYP/6-311++G(2df,2pd)/DPCM/saled-UAKS level. In the first part, two possible reaction mechanisms-associative and dissociative were compared. It was found that the dissociative mechanism of the hydration process is kinetically slightly preferred. Another important conclusion concerns the reaction channels. It was found that substitution of chloride ligand (abbreviated in the text as dechlorination reaction) represents energetically and kinetically the most feasible pathway. In the second part the same hydration reaction was explored for reactivity comparison of the Ru(II)-complexes with several derivatives of nalidixic acid: cinoxacin, ofloxacin, and (thio)nalidixic acid. The hydration process is about four orders of magnitude faster in a basic solution compared to neutral/acidic environment with cinoxacin and nalidixic acid as the most reactive complexes in the former and latter environments, respectively. The explored hydration reaction is in all cases endergonic; nevertheless the endergonicity is substantially lower (by ∼6 kcal/mol) in basic environment. © 2016 Wiley Periodicals, Inc. PMID:27185047

  9. Interactions of the "piano-stool" [ruthenium(II)(η(6) -arene)(quinolone)Cl](+) complexes with water; DFT computational study.

    PubMed

    Zábojníková, Tereza; Cajzl, Radim; Kljun, Jakob; Chval, Zdeněk; Turel, Iztok; Burda, Jaroslav V

    2016-07-15

    Full optimizations of stationary points along the reaction coordinate for the hydration of several quinolone Ru(II) half-sandwich complexes were performed in water environment using the B3PW91/6-31+G(d)/PCM/UAKS method. The role of diffuse functions (especially on oxygen) was found crucial for correct geometries along the reaction coordinate. Single-point (SP) calculations were performed at the B3LYP/6-311++G(2df,2pd)/DPCM/saled-UAKS level. In the first part, two possible reaction mechanisms-associative and dissociative were compared. It was found that the dissociative mechanism of the hydration process is kinetically slightly preferred. Another important conclusion concerns the reaction channels. It was found that substitution of chloride ligand (abbreviated in the text as dechlorination reaction) represents energetically and kinetically the most feasible pathway. In the second part the same hydration reaction was explored for reactivity comparison of the Ru(II)-complexes with several derivatives of nalidixic acid: cinoxacin, ofloxacin, and (thio)nalidixic acid. The hydration process is about four orders of magnitude faster in a basic solution compared to neutral/acidic environment with cinoxacin and nalidixic acid as the most reactive complexes in the former and latter environments, respectively. The explored hydration reaction is in all cases endergonic; nevertheless the endergonicity is substantially lower (by ∼6 kcal/mol) in basic environment. © 2016 Wiley Periodicals, Inc.

  10. Controlling the redox properties of a pyrroloquinolinequinone (PQQ) derivative in a ruthenium(II) coordination sphere.

    PubMed

    Mitome, Hiroumi; Ishizuka, Tomoya; Shiota, Yoshihito; Yoshizawa, Kazunari; Kojima, Takahiko

    2015-02-21

    Ruthenium(ii) complexes of PQQTME, a trimethyl ester derivative of redox-active PQQ (pyrroloquinolinequinone), were prepared using a tridentate ligand, 2,2':6',2''-terpyridine (terpy) as an auxiliary ligand. The characterization of the complexes was performed by spectroscopic methods, X-ray crystallography, and electrochemical measurements. In one complex, the pyridine site of PQQTME binds to the [Ru(II)(terpy)] unit as a tridentate ligand, and a silver(i) ion is coordinated by the quinone moiety in a bidentate fashion. In contrast, another complex includes the [Ru(II)(terpy)] unit at the bidentate quinone moiety of the PQQTME ligand. The difference in the coordination modes of the complexes exhibits a characteristic difference in the stability of metal coordination and also in the reversibility of the reduction processes of the PQQTME ligand. It should be noted that an additional metal-ion-binding to the PQQTME ligand largely raises the 1e(-)-reduction potential of the ligand. In addition, we succeeded in the characterization of the 1e(-)-reduced species of the complexes, where the unpaired electron was delocalized in the π-conjugated system of the PQQTME˙(-) ligand, using UV-Vis absorption and ESR spectroscopies.

  11. Competitive Binding Sites of a Ruthenium Arene Anticancer Complex on Oligonucleotides Studied by Mass Spectrometry: Ladder-Sequencing versus Top-Down

    NASA Astrophysics Data System (ADS)

    Wu, Kui; Hu, Wenbing; Luo, Qun; Li, Xianchan; Xiong, Shaoxiang; Sadler, Peter J.; Wang, Fuyi

    2013-03-01

    We report identification of the binding sites for an organometallic ruthenium anticancer complex [( η 6-biphenyl)Ru(en)Cl][PF6] ( 1; en = ethylenediamine) on the 15-mer single-stranded oligodeoxynucleotides (ODNs), 5'-CTCTCTX7G8Y9CTTCTC-3' [X = Y = T ( I); X = C and Y = A ( II); X = A and Y = T ( III); X = T and Y = A ( IV)] by electrospray ionization mass spectrometry (ESI-MS) in conjunction with enzymatic digestion or tandem mass spectrometry (top-down MS). ESI-MS combined with enzymatic digestion (termed MS-based ladder-sequencing), is effective for identification of the thermodynamically-favored G-binding sites, but not applicable to determine the thermodynamically unstable T-binding sites because the T-bound adducts dissociate during enzymatic digestion. In contrast, top-down MS is efficient for localization of the T binding sites, but not suitable for mapping ruthenated G bases, due to the facile fragmentation of G bases from ODN backbones prior to the dissociation of the phosphodiester bonds. The combination of the two MS approaches reveals that G8 in each ODN is the preferred binding site for 1, and that the T binding sites of 1 are either T7 or T11 on I and IV, and either T6 or T11 on II and III, respectively. These findings not only demonstrate for the first time that T-bases in single-stranded oligonucleotides are kinetically competitive with guanine for such organoruthenium complexes, but also illustrate the relative merits of the combination of ladder-sequencing and top-down MS approaches to elucidate the interactions of metal anticancer complexes with DNA.

  12. Ruthenium—Arene Complexes Derived from NHC•CO2 and NHC•CS2 Zwitterionic Adducts and Their Use in Olefin Metathesis

    NASA Astrophysics Data System (ADS)

    Delaude, Lionel; Demonceau, Albert

    A range of imidazol(in)ium-2-carboxylates and -dithiocarboxylates bearing alkyl or aryl groups on their nitrogen atoms were prepared by reacting the corresponding N-heterocyclic carbenes (NHCs) with either carbon dioxide or carbon disulfide. All the zwitterionic products were characterized by various analytical techniques, including thermogravimetric analysis (TGA). Their ability to act as NHC ligand precursors for in situ catalytic applications was investigated in the ruthenium-promoted ring-opening metathesis polymerization (ROMP) of cyclo-octene. Upon exposure to the [RuCl2(p-cymene)]2 dimer, the NHC CO2 adducts readily dissociated to generate [RuCl2(p-cymene)(NHC)] complexes that were highly active catalyst precursors for olefin metathesis. Conversely, the NHC CS2 betaines retained their zwitterionic nature and led to new cationic complexes of the [RuCl(p-cymene)(NHC CS2)]+PF6 - type that were devoid of any significant catalytic activity in the reaction under consideration

  13. Time resolved study of three ruthenium(II) complexes at micellar surfaces: A new long excited state lifetime probe for determining critical micelle concentration of surfactant nano-aggregates.

    PubMed

    Patra, Digambara; Chaaban, Ahmad H; Darwish, Shaza; Saad, Huda A; Nehme, Ali S; Ghaddar, Tarek H

    2016-02-01

    Three different ruthenium complexes have been synthesized and their luminescence properties in different solvent environments are reported. Luminescence intensities and excited state lifetimes of Ru-I, Ru-II and Ru-III vary with solvent viscosity. The excited state lifetime of Ru-I linearly increases in the viscosity range 1.76-12,100cP. Ru-II shows two linear increases: one in the low and another in the high viscosity ranges, whereas Ru-III illustrates a linear enhancement only in the low viscosity range. Interestingly, luminescence intensities and excited state lifetimes of Ru-I, Ru-II and Ru-III are found to be sensitive to nano-aggregation. However, the surfactant head charge and that of the ruthenium center as well as the hydrophobic tail of the ancillary ligand of the complexes have a great role in deciding the nature of the interaction and on the excited state properties at micellar surfaces. It is proposed that the long lifetime of Ru-III in water could be due to the coiling of the carbon chain of the ancillary ligand around the ruthenium center. At micelle surface, this coiling of the carbon chain is lost due to the parallel alignment with surfactants and thus quenching of the excited state lifetime is seen. Furthermore, it is shown that the variation of the excited state lifetime with respect to the change in surfactant concentration is a result of the formation of micelles from the surfactant monomer, thus, a novel technique for the determination of the critical micelle concentration (cmc) based on the long excited state lifetime of Ru-III located at the micellar nano-aggregates is reported.

  14. Half sandwich ruthenium(II) hydrides: hydrogenation of terminal, internal, cyclic and functionalized olefins.

    PubMed

    Bagh, Bidraha; Stephan, Douglas W

    2014-11-01

    Bis(1,2,3-triazolylidene) silver(I) complex 1a was reacted with [RuCl2(p-cymene)]2 to give the ruthenium complex [PhCH2N2(NMe)C2(C6H4CF3)]RuCl2(p-cymene) (2a) as major product in addition to the minor C(sp(2))-H activated product [PhCH2N2(NMe)C2(C6H3CF3)]RuCl(p-cymene) (2a'). Similar ruthenium complexes 2b, 2c, 2d and 2e with general formula RuCl2(p-cymene)(NHC) (NHC = MesCH2N2(NMe)C2Ph 2b, PhCH2N2(NMe)C2Ph 2c, TripCH2N2(NMe)C2Ph 2d, IMes 2e) were also synthesized. Subsequent reaction of Me3SiOSO2CF3 with 2a and 2b resulted in cationic ruthenium species [(PhCH2N2(NMe)C2(C6H4CF3))RuCl(p-cymene)][OSO2CF3] (3a) and [(MesCH2N2(NMe)C2Ph)RuCl(p-cymene)][OSO2CF3] (3b), respectively. Complexes 3a and 3b dissolved in CD3CN to give [(PhCH2N2(NMe)C2(C6H4CF3))RuCl(CD3CN)(p-cymene)][OSO2CF3] (4a) and [(MesCH2N2(NMe)C2Ph)RuCl(CD3CN)(p-cymene)][OSO2CF3] (4b), respectively. Cationic ruthenium species 4a and 4b failed to show catalytic activity towards hydrogenation of olefins. Ruthenium(II) complexes 2b-e with the general formula RuCl2(p-cymene)(NHC) were reacted with Et3SiH to generate a series of ruthenium(II) hydrides 5b-e. These compounds 5b-e are effective catalysts for the hydrogenation of terminal, internal and cyclic and functionalized olefins. PMID:25208607

  15. Arene-Alkene Cycloaddition.

    PubMed

    Remy, Richard; Bochet, Christian G

    2016-09-14

    Cycloadditions are among the most efficient chemical processes, combining atom economy, stereospecificity, and the ability to generate molecular complexity in a single step. Aromatic rings would in principle be ideal reaction partners, as they contain, at least from the topological point of view, both olefinic and diene subunits; however, the stability of the conjugated aromatic system would be broken by cycloaddition reactions, which are therefore rarely applied, because kinetics and thermodynamics hinder the process. From that aspect, photochemical activation opens interesting perspectives, as one can selectively provide excess energy to one of the reactants but not to the product, thus preventing thermal back reaction. Indeed, aromatic rings show a rich photochemistry, ranging from isomerizations, substitutions, and additions to cycloadditions. In this review, we will focus on cycloadditions, covering literature from early observations up to the present.

  16. The influence of a solvent on the aggregation of ruthenium(II) tetra-15-crown-5-phthalocyaninate

    NASA Astrophysics Data System (ADS)

    Grishina, A. D.; Zolotarevskii, V. I.; Gorbunova, Yu. G.; Pereshivko, L. Ya.; Enakieva, Yu. Yu.; Krivenko, T. V.; Savel'Ev, V. V.; Vannikov, A. V.; Tsivadze, A. Yu.

    2009-11-01

    The images of ensembles of ruthenium(II) complexes with tetra-15-crown-5-phthalocyanine and axially coordinated triethylenediamine molecules, (R4Pc)Ru(TED)2, obtained on an atomic force microscope were analyzed. A comparison with the X-ray structure analysis data was performed to estimate the number and mutual arrangement (architecture) of molecules in supramolecular aggregates depending on the nature of the solvent and the temperature of solutions before casting. Storage at room temperature or heating of a solution of the complex in tetrachloroethane caused the formation of stable supramolecular “wires” 600 nm or more long. The z-scanning method was used to study the third-order nonlinear optical characteristics of solutions of the (R4Pc)Ru(TED)2 complex in tetrachloroethane.

  17. Conformational isomerism in the solid-state structures of tetracaine and tamoxifen with para-sulphonato-calix[4]arene

    NASA Astrophysics Data System (ADS)

    Danylyuk, Oksana; Monachino, Melany; Lazar, Adina N.; Suwinska, Kinga; Coleman, Anthony W.

    2010-02-01

    The solid-state complexes between para-sulphonato-calix[4]arene and the drugs tamoxifen and tetracaine show an unusual 4:1 guest-host stoichiometry with formation of hydrophobic layer of drug molecules held between bilayers of para-sulphonato-calix[4]arene. In both structures each of the four independent drug molecules adopts different conformation due to the different mode of interaction with the anionic host, the neighbouring drug cations and water molecules.

  18. Calix[4]arene Based Single-Molecule Magnets

    SciTech Connect

    Karotsis, Georgios; Teat, Simon J.; Wernsdorfer, Wolfgang; Piligkos, Stergios; Dalgarno, Scott J.; Brechin, Euan K.

    2009-06-04

    -8) also suggests they should be excellent candidates as ligands for the isolation of molecular magnets, but to date their use in the isolation of paramagnetic cluster compounds is rather limited. Herein we present the first Mn cluster and the first SMM to be isolated using any methylene bridged calix[n]arene - a ferromagnetically coupled mixed-valence [Mn{sub 2}{sup III}Mn{sub 2}{sup II}] complex housed between either two TBC4s or two C4s.

  19. Transition-metal-catalyzed direct arylation of (hetero)arenes by C-H bond cleavage.

    PubMed

    Ackermann, Lutz; Vicente, Rubén; Kapdi, Anant R

    2009-01-01

    The area of transition-metal-catalyzed direct arylation through cleavage of C-H bonds has undergone rapid development in recent years, and is becoming an increasingly viable alternative to traditional cross-coupling reactions with organometallic reagents. In particular, palladium and ruthenium catalysts have been described that enable the direct arylation of (hetero)arenes with challenging coupling partners--including electrophilic aryl chlorides and tosylates as well as simple arenes in cross-dehydrogenative arylations. Furthermore, less expensive copper, iron, and nickel complexes were recently shown to be effective for economically attractive direct arylations.

  20. Why Aren't Philosophers and Educators Speaking to Each Other? Some Reasons for Hope.

    ERIC Educational Resources Information Center

    Ellett, Frederick S., Jr.

    2002-01-01

    Responds to Arcilla's article, "Why Aren't Philosophers and Educators Speaking to One Another?" noting complexities that complicate the answer and suggesting that they are indeed communicating if one accepts a broader definition of philosophers and educators. The essay asserts that little educational research and theory has had much influence on…

  1. Development of degradative techniques for coal chemistry based on ether cleavage reactions and metal arene chemistry

    SciTech Connect

    Lemke, D.W.

    1988-01-01

    The degradation of C-O and C-C bonds have been examined using model compounds that are similar in structure to those found in coal and other natural products. The conditions to maximize ether cleavage and minimize the formation of undesirable side products were determined by varying the concentration of reagents, temperature, and reaction time. 2-Phenoxynaphthalene (1) and 1-methoxypyrene (2) were the compounds examined. The optimum conditions demonstrated complete disappearance of 1 and 2, mass recoveries were above 84%, and the formation of reduced dimers in less than 10 mole % yield. The possibility of cleaving a C-C bond by a (3+2) cycloaddition and subsequent cycloreversion reactions was examined by treating a variety of dipolarphiles with deprotonated (({eta}{sup 6}-arene)FeCp){sup +} complexes (arene = hexamethylbenzene or tetralin) Azides and ozone were found to add quantitatively to the metal-arene complexes. Upon decomplexation of the ring, moderated yields of benzyl substituted products were isolated. The mechanism of this reaction is yet unknown but is postulated to occur by direct nucleophilic addition of the complex anion to the most electropositive atom of the dipolarphile. Chemical and electrochemical oxidation techniques were applied to the deprotonated (({eta}{sup 6}-arene)FeCp){sup +} complexes. Only minor yields of benzylic oxidation products were observed.

  2. Molecular binding behavior of bipyridium derivatives by water-soluble carboxylato-biphen[3]arene.

    PubMed

    Ma, Junwei; Deng, Hongmei; Ma, Suxiang; Li, Jian; Jia, Xueshun; Li, Chunju

    2015-04-18

    Complexation of two types of dicationic bipyridium guests, paraquat derivatives and bis(N-mono-substituted bipyridine) cations, by a negatively charged carboxylato-biphen[3]arene (CBP3) in water is reported. CBP3 could strongly interact with these guests, where charge-transfer and electrostatic interactions play important roles.

  3. Molecular recognition of curcumin (Indian Ayurvedic medicine) by the supramolecular probe, p-t-butyl calix(8)arene

    NASA Astrophysics Data System (ADS)

    Meenakshi, C.; Jayabal, P.; Ramakrishnan, V.

    2014-06-01

    The thermodynamic property of the host-guest complexes formed between the curcumin, component of Indian Ayurvedic medicine turmeric, a drug molecule, with the supra molecule, p-t-butyl calix(8)arene was studied. p-t-Butyl calix(8)arene has been used as a host molecule and curcumin as a guest molecule. Optical absorption spectral studies were carried out to investigate the molecular recognition properties of p-t-butyl calix(8)arene with curcumin. The stochiometry of the host-guest complexes formed and the binding constant were determined. An interesting 1:1 and 4:1 stochiometric host-guest complexes were formed. Job's continuous method of variation and Benesi-Hildebrand expression were used for the determination of binding constant and the stochiometry of the host-guest complex formed.

  4. Molecular recognition of curcumin (Indian Ayurvedic medicine) by the supramolecular probe, p-t-butyl calix(8)arene.

    PubMed

    Meenakshi, C; Jayabal, P; Ramakrishnan, V

    2014-06-01

    The thermodynamic property of the host-guest complexes formed between the curcumin, component of Indian Ayurvedic medicine turmeric, a drug molecule, with the supra molecule, p-t-butyl calix(8)arene was studied. p-t-Butyl calix(8)arene has been used as a host molecule and curcumin as a guest molecule. Optical absorption spectral studies were carried out to investigate the molecular recognition properties of p-t-butyl calix(8)arene with curcumin. The stochiometry of the host-guest complexes formed and the binding constant were determined. An interesting 1:1 and 4:1 stochiometric host-guest complexes were formed. Job's continuous method of variation and Benesi-Hildebrand expression were used for the determination of binding constant and the stochiometry of the host-guest complex formed.

  5. Accessible gold clusters using calix[4]arene N-heterocyclic carbene and phosphine ligands.

    PubMed

    Nigra, Michael M; Yeh, Alexander J; Okrut, Alexander; DiPasquale, Antonio G; Yeh, Sheila W; Solovyov, Andrew; Katz, Alexander

    2013-09-21

    We investigate the synthesis of accessible calix[4]arene-bound gold clusters consisting of open "coordinatively unsaturated" active sites, using a comparative approach that relies on calix[4]arene ligands with various upper- and lower-rim substituents. In contrast with a reported Au(I)-tert-butyl-calixarene phosphine complex, which exhibits a single cone conformer in solution, the H upper-rim analog exhibits multiple conformers in solution. This contrasts with observations of the tert-butyl upper-rim analog, which exhibits a single cone conformer in solution under similar conditions. In the solid state, as determined by single-crystal X-ray diffraction, both H and tert-butyl upper-rim analogs exhibit exclusively cone conformer. A detailed structural analysis of these two solid-state structures highlights a CH-π interaction involving a methoxy lower-rim substituent and phenyl substituent on P as the key feature that enforces a tight configuration of Au(I) atoms on the same side of the calix[4]arene lower-rim plane. We hypothesize that such a configuration promotes chelation of the ligand to a gold surface and facilitates the synthesis of small Au11-sized clusters after reduction of both complexes. The new cluster, like the one reported with the tert-butyl analog, has an extraordinary 25% of surface atoms that are open and accessible to a 2-NT (2-naphthalenethiol) probe in solution. We also investigated the effect of calix[4]arene lower-rim substituents that coordinate to the metal, by using N-heterocyclic carbene (NHC) functional groups rather than phosphines. Four small (<1.6 nm diameter) calix[4]arene NHC-bound gold clusters were synthesized, including three using novel calix[4]arene NHC ligands. The smallest calix[4]arene NHC-bound Au cluster consisted of a 1.2 nm gold core, and its number density of accessible and open surface sites was measured. This required development of a new titration method for open sites on gold clusters, using a SAMSA fluorescein dye

  6. The tricarbonylchromium template for stereocontrol in radical reactions of arenes.

    PubMed

    Merlic, C A; Walsh, J C

    2001-04-01

    Chromium tricarbonyl complexed aryl aldeyhydes and ketones underwent Sm(II)-promoted radical lactone formation in the presence of alpha,beta-unsaturated esters to produce diastereomerically pure lactones in good yields. The completely diastereoselective lactone formation involves capture of the benzylic ketyl radical by the ester anti to the chromium tricarbonyl moiety. The relative stereochemistry of the lactone and chromium tricarbonyl moieties was proven by X-ray crystallography and supports the proposed mechanism. Enantiopure chromium tricarbonyl complexed arenes afforded single enantiomers when subjected to Sm(II)-promoted radical lactone formation condiditions. The enantio- and diastereomerically pure chromium tricarbonyl complexed lactones were subsequently treated with BF3.OEt2 to generate a mixture of diastereomers via Lewis acid promoted chromium tricabonyl directed cationic rearrangement. The diastereomers were separated and individually decomplexed with I2 to afford both of the corresponding chromium-free enantiomerically pure lactones starting from a single enantiomerically pure chromium tricarbonyl complex. PMID:11281765

  7. Introduction of luminescent rhenium(I), ruthenium(II), iridium(III) and rhodium(III) systems into rhodamine-tethered ligands for the construction of bichromophoric chemosensors.

    PubMed

    Wang, Chunyan; Lam, Ho-Chuen; Zhu, Nianyong; Wong, Keith Man-Chung

    2015-09-14

    Several classes of luminescent transition metal complexes, including rhenium(I) tricarbonyl diimine, ruthenium(II) diimine, cyclometallated iridium(III) and rhodium(III) diimine, as well as ruthenium(II) and iridium(III) terpyridine systems, tethered with rhodamine moieties, have been synthesized and characterized. The X-ray crystal structure of one cyclometallated rhodium(III) diimine (11) with a rhodamine pendant was determined. Most of the complexes were found to exhibit emission in fluid solution at room temperature. Depending on the nature of the transition metal system, the emission origin was mainly assigned to be derived from the triplet excited state of the metal-to-ligand charge transfer ((3)MLCT) or the intraligand ((3)IL) transition. The cation-binding properties of these complexes toward various cations were investigated by electronic absorption and emission spectroscopy. Some of them were found to exhibit new low-energy absorption and emission bands, attributed to the ring opening of the rhodamine moiety, with high selectivity and/or high sensitivity for various cations, in agreement with sensing and spectroscopic behaviours of the rhodamine derivative. Depending on the nature of the transition metal centres, the chelating ligands as well as the linker to the rhodamine derivative, different sensing properties in terms of selectivity, sensitivity and binding stability, could be obtained.

  8. Host-guest interaction of flavanone and 7-aminoflavone with C-Hexylpyrogallol[4]arene

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Sowrirajan; Enoch, Israel V. M. V.

    2014-11-01

    In this paper, we report the structures of the host-guest complexes of flavanone and 7-aminoflavone (guests) with C-Hexylpyrogallol[4]arene (host). The study of the host-guest binding is carried out using UV-Visible absorption, steady-state and time-resolved fluorescence, and 2D ROESY spectroscopy. The stoichiometry and the binding constant of the C-Hexylpyrogallol[4]arene-guest complexes are reported based on absorption and fluorescence titrations. Both flavanone and 7-aminoflavone form 1:1 complexes with the host with binding constant values of 1.71 × 104 mol-1 dm3 and 2.06 × 104 mol-1 dm3 respectively. Fluorescence quenching of the two flavonoids on complex formation occurs and the Stern-Volmer constants are reported. The mode of binding of flavanone and 7-aminoflavone with the host molecule is optimized with 2D ROESY and the structures of the inclusion complexes are proposed.

  9. Synthesis of 9,10-bis-ketoenaminoanthryl and 9,10-bis-isoxazolylanthryl linked biscalix[4]arenes: atropisomers and molecular recognitions.

    PubMed

    Tsai, Chia-Chen; Ho, I-Ting; Chu, Jean-Ho; Shen, Li-Ching; Huang, Shou-Ling; Chung, Wen-Sheng

    2012-03-01

    An efficient synthetic pathway for the synthesis of biscalix[4]arenes 5-10 using 1,3-dipolar cycloaddition reactions is reported. Biscalix[4]arene 10 is capable of forming a complex with methyl viologen because of favorable cation-π interactions and a proper cavity size to accommodate the guest. Moreover, biscalix[4]arenes 8a and 8b were found to be atropisomers at room temperature. These two conformers were unable to exchange at room temperature because of the restricted rotation of the C(9)-C(11) or C(10)-C(12) bonds of the β-amino-α,β-unsaturated ketones of anthracene.

  10. Pentanuclear lanthanide pyramids based on thiacalix[4]arene ligand exhibiting slow magnetic relaxation.

    PubMed

    Ge, Jing-Yuan; Ru, Jing; Gao, Feng; Song, You; Zhou, Xin-Hui; Zuo, Jing-Lin

    2015-09-21

    A series of pentanuclear Ln(III) clusters, [Ln5(μ4-OH)(μ3-OH)4(L1)(acac)6] (H4L1 = p-tert-butylthiacalix[4]arene; acac = acetylacetonate; Ln = Dy, Ho, Er) and [Ln5(μ5-OH)(μ3-OH)4(L1)(L2)2(acac)2(CH3OH)2] (H3L2 = 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,26,27-trihydroxy-28-methoxy thiacalix[4]arene; Ln = Dy, Ho, Er), have been synthesized based on the thiacalix[4]arene ligand. All of these complexes feature a square-based pyramid with four triangular Ln3 structural motifs. One μ4-OH group bridges four Ln(III) ions in the basal plane of , while the OH group in complexes adopts the μ5-coordination mode. Our results illuminate the coordination modes of the versatile thiacalix[4]arene ligands and their application to new cluster compounds. The structural and magnetic studies confirm that the molecular symmetries and coordination geometries for lanthanide metal cores have a significant effect on some parameters as single-molecule magnets. Among them, two Dy5 pyramids exhibit distinct slow magnetic relaxation. PMID:26237158

  11. Chemoenzymatic synthesis of monocyclic arene oxides and arene hydrates from substituted benzene substrates.

    PubMed

    Boyd, Derek R; Sharma, Narain D; Ljubez, Vera; McGeehin, Peter K M; Stevenson, Paul J; Blain, Marine; Allen, Christopher C R

    2013-05-14

    Enantiopure cis-dihydrodiol bacterial metabolites of substituted benzene substrates were used as precursors, in a chemoenzymatic synthesis of the corresponding benzene oxides and of a substituted oxepine, via dihydrobenzene oxide intermediates. A rapid total racemization of the substituted benzene 2,3-oxides was found to have occurred, via their oxepine valence tautomers, in accord with predictions and theoretical calculations. Reduction of a substituted arene oxide to yield a racemic arene hydrate was observed. Arene hydrates have also been synthesised, in enantiopure form, from the corresponding dihydroarene oxide or trans-bromoacetate precursors. Biotransformation of one arene hydrate enantiomer resulted in a toluene-dioxygenase catalysed cis-dihydroxylation to yield a benzene cis-triol metabolite.

  12. Synthesis of arene-soluble mixed-metal Zr/Ce, Zr/Y, and related {l_brace}[Zr{sub 2}(O{sup i}Pr){sub 9}]LnX{sub 2}{r_brace}{sub n} complexes using the dizirconium nonaisopropoxide ligand

    SciTech Connect

    Evans, W.J.; Johnston, M.A.; Greci, M.A.; Ansari, M.A.; Brady, J.C.; Ziller, J.W.

    2000-05-15

    The utility of polydentate monoanionic [Zr{sub 2}(O{sup i}Pr){sub 9}]{sup {minus}} in generating arene-soluble, unsolvated, mixed-metal Zr/Ce and Zr/Y complexes is described. The synthesis of other mixed-metal zirconium lanthanide complexes was also studied to explore the relationship of metal size to structure. Lanthanide trihalides react in THF with KZr{sub 2}(O{sup i}Pr){sub 9} to form unsolvated dimers, {l_brace}[Zr{sub 2}(O{sup i}Pr){sub 9}][LnCl{sub 2}{r_brace}{sub 2}], with the larger metals, Ln = Ce (1), Ho (2), Y (3), and unsolvated monomers, [Zr{sub 2}(O{sup i}Pr){sub 9}]LnCl{sub 2}, with the smaller elements, Ln = Er (4), Yb (5). The synthesis of a monomeric iodide analogue, [Zr{sub 2}(O{sup i}Pr){sub 9}]TmI{sub 2}, 6, by reduction of Zr{sub 2}(O{sup i}Pr){sub 8}({sup i}PrOH){sub 2} with TmI{sub 2}(DME){sub 3} is also reported. In all of these complexes, the [Zr{sub 2}(O{sup i}Pr){sub 9}]{sup {minus}} subunit is tetradentate. 1--6 are compared with related cyclopentadienyl halide complexes to evaluate the special features of the dizirconium nonaisopropoxide ligand versus cyclopentadienide.

  13. Transition metal cations extraction by ester and ketone derivatives of chromogenic azocalix[4]arenes.

    PubMed

    Ak, Metin; Taban, Deniz; Deligöz, Hasalettin

    2008-06-15

    The molecule of azocalix[n]arene is a macrocyclic used effectively in the complexation of the heavy metal pollutants (like silver and mercury). In this work, our main aim is to prepare new chromogenic azocalix[n]arene molecules to elaborate an extractant with high extractant selectivity for metal ions able to detect this type of pollutant. The solvent extraction properties of four acetyls, four methyl ketones and four benzoyls derivatives from azocalix[4]arenes which were prepared by linking 4-ethyl, 4-n-butyl, 4-acetamid anilin and 2-aminothiazol to calix[4]arene through a diazo-coupling reaction, the alkaline earth (Sr2+) and the transition (Ag+, Hg2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Cr3+) metal cations have been determined by extraction studies with metal picrates. Both ketones are better extractants than esters, and show a strong preference for Ag+, while Cu2+ and Cr3+ are the most extracted cation with the esters. Both acetyl and benzoyl esters are good carriers for Ag+ and Hg2+.

  14. Synthesis and Structure-Property Relationships in (h6-Arene)Cr(CO)3 Chemistry: From Guided Experiments to Discovery Research

    NASA Astrophysics Data System (ADS)

    Hunter, Allen D.; Bianconi, Larry J.; Dimuzio, Steven J.; Braho, Dianne L.

    1998-07-01

    (h6-Arene)Cr(CO)3 complexes are only moderately air sensitive and can easily and inexpensively be prepared from most of the arenes already found in organic stockrooms. Since instructors can have each student prepare a different complex, they are ideal targets for student directed "discovery research" lab projects. Teams of students can compare how their syntheses and the physical, spectroscopic, and electrochemical properties of their products vary as a function of the arenes structures. The resulting empirical structure/property correlations can then be rationalized in terms of various bonding models. A discussion of (h6-arene)Cr(CO)3 chemistry suitable for student handouts is included along with suggestions for extending this experiment to create multi-step organic and inorganic synthesis projects. In addition, generic procedures for the syntheses using relatively simple glassware, example reaction procedures at both micro and conventional scales, practical hints for carrying out the syntheses, a discussion of substituent effects on arene suitability, lists of required equipment, and diagrams of the assembled glassware are included. Characterization data for over five dozen (h6-Arene)Cr(CO)3 complexes are tabulated. These data are particularly suitable for use as lecture, examination, and/or problem set examples in discussions of the relationships between structure, bonding, spectroscopy, electrochemistry, and reactivity in organometallic chemistry.

  15. Study on the inclusion interaction of p-sulfonated calix[ n]arenes with Vitamin K 3 using methylene blue as a spectral probe

    NASA Astrophysics Data System (ADS)

    Lu, Qin; Gu, Jiashan; Yu, Huapeng; Liu, Chun; Wang, Lun; Zhou, Yunyou

    2007-09-01

    The characteristics of host-guest complexation between p-sulfonated calix[ n]arene ( SCnA, n = 4, 6) and Vitamin K 3 ( VK3) were investigated by fluorescence spectrometry and absorption spectrometry using methylene blue ( MB) as a probe. Interaction with MB and SCnA led to an obvious decrease in fluorescence intensity of MB, accompanying with shifts of emission peaks. Absorption peaks also showed interesting changes; however, when VK3 was added, fluorescence intensity and absorbance recovered and a slight and slow red shift was observed. The obtained results showed that the inclusion ability of p-sulphonated calix[ n]arenes towards VK3 was the order: p-sulphonated calix[6]arene ( SC6A) > p-sulphonated calix[4]arene ( SC4A). Relative mechanism was proposed to explain the inclusion process.

  16. Photodissociation of cyclopentadienyliron(II) arene cations: Detection and characterization of reactive intermediates by means of time-resolved laser spectroscopy

    SciTech Connect

    Chrisope, D.R.; Park, Kyungmi; Schuster, G.B. )

    1989-08-02

    Cyclopentadienyliron(II) arene cations ((CpFeArH){sup +}) exist in solution as a mixture of freely solvated ions and as ion pairs with an anionic counterion (X{sup {minus}}). Irradiation of either the free ion or the ion pair in solutions containing benzonitrile (PhCN) leads to loss of the arene ligand and formation of a tris-nitrile complex ((CpFe(PhCN){sub 3}){sup +}). Two important reactive intermediates are detected by time-resolved laser spectroscopy. One, formed from irradiation of the ion pair, is assigned as the ring-slipped {eta}{sup 4}-arene-Cp-iron compound covalently bound to its counterion. The other, formed from irradiation of freely solvated cations, is assigned as the coordinatively unsaturated ring-slipped Cp-iron-{eta}{sup 4}-arene compound. The role of these intermediates in the ligand-exchange reaction was examined.

  17. Electrochemical Studies for Cation Recognition with Diazo-Coupled Calix[4]arenes

    PubMed Central

    Kim, Bongsu; Kim, Tae Hyun

    2015-01-01

    The electrochemical properties of diazophenylcalix[4]arenes bearing ortho-carboxyl group (o-CAC) and ortho-ester group (o-EAC), respectively, in the presence of various metal ions were investigated by voltammetry in CH3CN. o-CAC and o-EAC showed voltammetric changes toward divalent metal ions and no significant changes with monovalent alkali metal ions. However, o-CAC preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in voltammetric signals are observed in o-EAC with alkaline earth metal ions. o-EAC only binds with other transition metal ions. This can be explained on metal ion complexation-induced release of proton from the azophenol to the quinone-hydrazone tautomer followed by internal complexation of the metal ion with aid of nitrogen atoms and ortho-carbonyl groups in the diazophenylazocalix[4]arenes. PMID:25785231

  18. Theoretical study of a novel imino bridged pillar[5]arene derivative

    NASA Astrophysics Data System (ADS)

    Xie, Ju; Zuo, Tongfei; Huang, Zhiling; Huan, Long; Gu, Qixin; Gao, Chenxi; Shao, Jingjing

    2016-10-01

    In this paper, we report a novel imino bridged pillar[5]arene derivative (P5N) for the first time. Four conformers (P5N0, P5N1, P5N12, and P5N13, arising due to the different orientation of Nsbnd H bond of imino bridging group) are obtained by quantum chemical calculations at the CAM-B3LYP/6-31+G(d, p) level of theory. The geometries, energies, electronic structures, and absorption spectra of P5N conformers as well as pillar[5]arene (P5) are discussed in detail. The inclusion complexes of paraquat (Pq) with P5N and P5, respectively, are also obtained at the same level of theory. Compared to P5, P5N exhibits better performance in inclusion complexation toward Pq.

  19. Mono- and Bimetallic Ruthenium—Arene Catalysts for Olefin Metathesis: A Survey

    NASA Astrophysics Data System (ADS)

    Borguet, Yannick; Sauvage, Xavier; Demonceau, Albert; Delaude, Lionel

    In this chapter, we summarize the main achievements of our group toward the development of easily accessible, highly efficient ruthenium—arene catalyst precursors for olefin metathesis. Major advances in this field are presented chronologically, with an emphasis on catalyst design and mechanistic details. The first part of this survey focuses on monometallic complexes with the general formula RuCl2(p-cymene)(L), where L is a phosphine or N-heterocyclic carbene ancillary ligand. In the second part, we disclose recent developments in the synthesis and catalytic applications of homobimetallic ruthenium—arene complexes of generic formula (p-cymene)Ru(μ-Cl)3RuCl(η2-C2H4)(L) and their derivatives resulting from the substitution of the labile ethylene moiety with vinylidene, allenylidene, or indenylidene units

  20. Conjugated polymers in an arene sandwich.

    PubMed

    McNeil, Anne J; Müller, Peter; Whitten, James E; Swager, Timothy M

    2006-09-27

    A series of poly(p-arylene butadiynylene)s containing zero, one, and two co-facial pi-pi interactions per repeat unit were synthesized and characterized. A surprisingly selective and high-yielding Diels-Alder cycloaddition of anthracene and nonsymmetric, sterically hindered anhydrides proved essential to generating the cofacial arene-containing monomers. Single-crystal X-ray structures display nearly parallel cofacial arenes that are within the van der Waals contact distances. The precursor molecules with cofacial arenes undergo reversible one- and two-electron oxidations to the radical cation and dication in CH2Cl2. The anhydrides were converted to N-alkyl imides to increase the solubility. High-molecular weight poly(p-arylene butadiynylene)s were prepared via Pd/Cu(I)/benzoquinone oxidative coupling of the diacetylene monomers. The resulting polymers are highly emissive in solution and thin films. The ionization potentials were measured using ultraviolet photoelectron spectroscopy with thin films. Last, fluorescence measurements of polymer thin films during continuous irradiation indicate that the most hindered polymer is more resistant to photobleaching.

  1. A photoresponsive wettability switch based on a dimethylamino calix[4]arene.

    PubMed

    Zhang, Xiaoyan; Zhao, Haiyang; Tian, Demei; Deng, Hongtao; Li, Haibing

    2014-07-21

    A photoreversible switch based on a photoresponsive host-guest system consisting of dimethylamino calix[4]arene L and 4-(phenylazo)benzoic acid (O) is reported. The host L exhibited selective binding and release of O on UV and visible irradiation at 450 and 365 nm, respectively. Moreover, the photoresponsive host-guest complex was applied as a photocontrolled wettability switch on a functional micro/nanostructured silicon surface, and is thus promising for applications in sensors and microfluidic devices.

  2. A high-barrier molecular balance for studying face-to-face arene-arene interactions in the solid state and in solution.

    PubMed

    Chong, Yong S; Carroll, William R; Burns, William G; Smith, Mark D; Shimizu, Ken D

    2009-09-14

    An atropisomeric molecular balance was developed to study face-to-face arene-arene interactions. The balance has a large central 1,4,5,8-naphthalene diimide surface that forms intramolecular arene-arene interactions with two pendent arms. The balance adopts distinct syn and anti isomers with varying numbers of intramolecular interactions. Thus, the strength of the arene-arene interaction could be quantitatively measured by NMR spectroscopy from the anti/syn ratios. The size of the arene arms was easily varied, which allowed examination of the relationship between arene size and strength of the interaction. A nonlinear size dependence was observed in solution with larger arene arms having a disproportionately stronger arene-arene interaction. The intramolecular arene-arene interactions were also characterized in the solid state by X-ray crystallography. These studies were facilitated by the kinetic stability of the syn and anti isomers at room temperature due to the high isomerization barrier (DeltaG=27.0 kcal mol(-1)). Thus, the anti isomer could be selectively isolated and crystallized in its folded conformation. The X-ray structures confirmed that the anti isomers formed two strong intramolecular arene-arene interactions with face-to-face geometries. The solid-state structure analysis also reveals that the rigid framework may contribute to the observed nonlinear size trend. The acetate linker is slightly too long, which selectively destabilizes the balances with smaller arene arms. The larger arene arms are able to compensate for the longer linker and form effective intramolecular arene-arene interactions.

  3. Synthesis, structure and molecular recognition of functionalised tetraoxacalix[2]arene[2]triazines.

    PubMed

    Wang, Qi-Qiang; Wang, De-Xian; Yang, Hai-Bo; Huang, Zhi-Tang; Wang, Mei-Xiang

    2010-06-25

    Functionalised dialkoxy-substituted tetraoxacalix[2]arene[2]triazine macrocycles 6 have been readily synthesised by the fragment coupling approach using methyl 3,5-dihydroxy-4-alkoxybenzoates and cyanuric chloride as the starting materials under very mild conditions. AlCl(3)-mediated deallylation and debenzylation reactions afforded the lower-rim dihydroxy-substituted tetraoxacalix[2]arene[2]triazine derivatives 11 and 13 in good yields. Although dialkoxy-substituted tetraoxacalix[2]arene[2]triazine macrocycles are fluxional in solution on the NMR spectroscopy timescale, they adopt a symmetric or slightly distorted 1,3-alternate conformation with the bridging oxygen atoms conjugated with the triazine rings. The dihydroxylated tetraoxacalix[2]arene[2]triazine 13 b, which gives a mixture of monomer and dimer in solution according to a diffusion NMR spectroscopy study, adopts a 1,3-alternate conformation and forms a cyclic tetrameric assembly in the solid state due to the formation of intermolecular hydrogen-bonding networks. This dihydroxylated macrocyclic host molecule, a hydrogen-bond donor macrocycle with a V-shaped cleft, interacts with 2,2'-bipyridine, 4,4'-bipyridine and 1,10-phenanthroline guests. Although in solution they form the corresponding 1:1 complexes with binding constants ranging from 37.7 to 213 M(-1), 2:2 host-guest complexes were observed in the crystalline state. Hydrogen-bonding interactions, along with other non-covalent interactions, such as lone-pair-electron-pi and C-H...pi interactions, were found to be the driving force for the formation of host-guest complexes.

  4. Half-sandwich ruthenium(II) biotin conjugates as biological vectors to cancer cells.

    PubMed

    Babak, Maria V; Plażuk, Damian; Meier, Samuel M; Arabshahi, Homayon John; Reynisson, Jóhannes; Rychlik, Błażej; Błauż, Andrzej; Szulc, Katarzyna; Hanif, Muhammad; Strobl, Sebastian; Roller, Alexander; Keppler, Bernhard K; Hartinger, Christian G

    2015-03-23

    Ruthenium(II)-arene complexes with biotin-containing ligands were prepared so that a novel drug delivery system based on tumor-specific vitamin-receptor mediated endocytosis could be developed. The complexes were characterized by spectroscopic methods and their in vitro anticancer activity in cancer cell lines with various levels of major biotin receptor (COLO205, HCT116 and SW620 cells) was tested in comparison with the ligands. In all cases, coordination of ruthenium resulted in significantly enhanced cytotoxicity. The affinity of Ru(II) -biotin complexes to avidin was investigated and was lower than that of unmodified biotin. Hill coefficients in the range 2.012-2.851 suggest strong positive cooperation between the complexes and avidin. To estimate the likelihood of binding to the biotin receptor/transporter, docking studies with avidin and streptavidin were conducted. These explain, to some extent, the in vitro anticancer activity results and support the conclusion that these novel half-sandwich ruthenium(II)-biotin conjugates may act as biological vectors to cancer cells, although no clear relationship between the cellular Ru content, the cytotoxicity, and the presence of the biotin moiety was observed. PMID:25676245

  5. New ruthenium(II) coordination compounds possessing bidentate aminomethylphosphane ligands: synthesis, characterization and preliminary biological study in vitro.

    PubMed

    Płotek, Michał; Starosta, Radosław; Komarnicka, Urszula K; Skórska-Stania, Agnieszka; Jeżowska-Bojczuk, Małgorzata; Stochel, Grażyna; Kyzioł, Agnieszka

    2015-08-21

    Addition of aminomethylphosphane P{CH2N(CH2CH2)2O}3 (), PPh2{CH2N(CH2CH2)2O} () or PPh2{CH2N(CH2CH2)2NCH2CH3} () to a methanolic solution of RuCl3 results in reduction of ruthenium(iii) ions giving finally ttt-[RuCl2()2] (), ttt-[RuCl2()2] () and ttt-[RuCl2()2] (). The synthesized complexes are the first examples of ruthenium(ii) coordination compounds possessing aminomethylphosphanes chelating via phosphorus and nitrogen atoms. They were fully characterized (NMR, ESI-MS, IR, elemental analysis, X-ray crystallography). Preliminary studies of the in vitro cytotoxicity on the A549 cell line (human lung adenocarcinoma) and interactions with human serum proteins (albumin and apotransferrin) showed moderate activity of the complexes. Interestingly, the P,N-chelation leads to formation of strained 4-membered Ru-P-C-N-Ru rings, which in the case of and undergo opening in the presence of CH3CN, which results in rearrangement to ctc-[RuCl2()2(CH3CN)2] () and ctc-[RuCl2()2(CH3CN)2] ().

  6. Nickel, Manganese, Cobalt, and Iron-Catalyzed Deprotonative Arene Dimerization

    PubMed Central

    Truong, Thanh; Alvarado, Joseph; Tran, Ly Dieu; Daugulis, Olafs

    2010-01-01

    A number of first-row transition metal salts catalyze deprotonative dimerization of acidic arenes. Under the atmosphere of oxygen, nickel, manganese, cobalt, and iron chlorides have been shown to dimerize five- and six-membered ring heterocycles as well as electron-poor arenes. Both tetramethylpiperidide and dicyclohexylamide bases can be employed; however, the former afford slightly higher yields. PMID:20192197

  7. Arene Selectivity by a Flexible Coordination Polymer Host.

    PubMed

    Wright, James S; Vitórica-Yrezábal, Iñigo J; Thompson, Stephen P; Brammer, Lee

    2016-09-01

    The coordination polymers [Ag4 (O2 CCF3 )4 (phen)3 ]⋅ phen⋅arene (1⋅phen⋅arene) (phen=phenazine; arene=toluene, p-xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o-xylene and m-xylene as the solvent yield the solvent-free coordination polymer [Ag4 (O2 CCF3 )4 (phen)2 ] (2). Toluene, p-xylene and benzene have been successfully used in mixed-arene syntheses to template the formation of coordination polymers 1⋅phen⋅arene, which incorporate o- or m-xylene. The selectivity of 1⋅phen⋅arene for the arene guests was determined, through pairwise competition experiments, to be p-xylene>toluene≈benzene>o-xylene>m-xylene. The largest selectivity coefficient was determined as 14.2 for p-xylene:m-xylene and the smallest was 1.0 for toluene:benzene. PMID:27483388

  8. Catalytic arene hydrogenation using early transition metal hydride compounds

    SciTech Connect

    Rothwell, I.P.

    1993-03-15

    Progress was achieved in four areas: development of surface supported Group 5 metal organometallic compounds for catalytic arene hydrogenation, isolation and reactivity of possible intermediates in catalytic arene hydrogenation, synthesis and characterization of new d[sup 0]-metal hydride compounds, and stoichiometric reactivity of d[sup 0] metal hydrido, aryloxide compounds. (DLC)

  9. Arene Selectivity by a Flexible Coordination Polymer Host.

    PubMed

    Wright, James S; Vitórica-Yrezábal, Iñigo J; Thompson, Stephen P; Brammer, Lee

    2016-09-01

    The coordination polymers [Ag4 (O2 CCF3 )4 (phen)3 ]⋅ phen⋅arene (1⋅phen⋅arene) (phen=phenazine; arene=toluene, p-xylene or benzene) have been synthesised from the solution phase in a series of arene solvents and crystallographically characterised. By contrast, analogous syntheses from o-xylene and m-xylene as the solvent yield the solvent-free coordination polymer [Ag4 (O2 CCF3 )4 (phen)2 ] (2). Toluene, p-xylene and benzene have been successfully used in mixed-arene syntheses to template the formation of coordination polymers 1⋅phen⋅arene, which incorporate o- or m-xylene. The selectivity of 1⋅phen⋅arene for the arene guests was determined, through pairwise competition experiments, to be p-xylene>toluene≈benzene>o-xylene>m-xylene. The largest selectivity coefficient was determined as 14.2 for p-xylene:m-xylene and the smallest was 1.0 for toluene:benzene.

  10. Partial cone calix[4]arene-crown-6-ethers

    SciTech Connect

    Das, G.; Sachleben, R.A.; Descazeaud, T.; Bryan, J.C.; Moyer, B.A.

    1997-12-31

    Partial cone calix[4] arene crown ethers represents a new category of lariat ethers. In general, calix arene crown ethers have been previously shown to be efficient extractants for metal cations. Appropriately substituted cone and 1, 3-alt conformers of calix crowns exhibit selectivities for Na{sup +} and Cs{sup +}, respectively. The partial cone conformers have not been as throughly studied. We have developed an efficient method of synthesis of partial cone calix[4]arene-crown ethers and have synthesized a variety of partial cone calix[4]arene crowns. Solution and solid-state structures of representative examples have been determined by {sup 1}H NMR spectroscopy and X-ray crystallography. Relative affinities of these partial cone calix[4]arene crowns for alkali metal ions have been investigated by solvent extraction techniques.

  11. Azacalix[6]arene hexamethyl ether: synthesis, structure, and selective uptake of carbon dioxide in the solid state.

    PubMed

    Tsue, Hirohito; Ishibashi, Koichi; Tokita, Satoshi; Takahashi, Hiroki; Matsui, Kazuhiro; Tamura, Rui

    2008-01-01

    To investigate dynamic solid-state complexation hitherto unexplored in nitrogen-bridged calixarene analogues, azacalix[6]arene hexamethyl ether has been prepared in three steps by applying a 5+1 fragment-coupling approach by using a Buchwald- Hartwig aryl amination reaction with the aid of our previously devised temporal N-silylation protocol. X-ray crystallographic analysis and NMR spectroscopic measurements have revealed that the azacalix[6]arene is well endowed with hydrogen-bonding ability, by which both the molecular and crystal structures are controlled. The azacalix[6]arene is conformationally flexible in solution on the NMR time scale, whereas it adopts a definite 1,2,3-alternate conformation with S2 symmetry in the solid state as a result of intramolecular bifurcated hydrogen-bonding interactions. In the crystal, molecules of the azacalix[6]arene are mutually interacted by intermolecular hydrogen bonds to establish one-dimensional hexane-filled nanochannel crystal architecture. Although the single crystal was broken after desolvation, the resultant polycrystalline powder material was capable of selectively adsorbing CO2 among the four main gaseous components of the atmosphere. In contrast, carbocyclic p-tert-butylcalix[6]arene hexamethyl ether, the crystal structure of which was also elucidated for the first time in the present study, gave rise to almost no uptake of CO2. Additional solid-gas adsorption experiments for another three gases, such as N2, O2, and Ar, suggested that quadrupole/induced-dipole interactions and/or hydrogen-bonding interactions played an important role in permitting the observed selective uptake of CO2 by this new azacalix[6]arene in the solid state.

  12. Bis-tert-Alcohol-Functionalized Crown-6-Calix[4]arene: An Organic Promoter for Nucleophilic Fluorination.

    PubMed

    Jadhav, Vinod H; Choi, Wonsil; Lee, Sung-Sik; Lee, Sungyul; Kim, Dong Wook

    2016-03-18

    A bis-tert-alcohol-functionalized crown-6-calix[4]arene (BACCA) was designed and prepared as a multifunctional organic promoter for nucleophilic fluorinations with CsF. By formation of a CsF/BACCA complex, BACCA could release a significantly active and selective fluoride source for SN2 fluorination reactions. The origin of the promoting effects of BACCA was studied by quantum chemical methods. The role of BACCA was revealed to be separation of the metal fluoride to a large distance (>8 Å), thereby producing an essentially "free" F(-). The synergistic actions of the crown-6-calix[4]arene subunit (whose O atoms coordinate the counter-cation Cs(+)) and the terminal tert-alcohol OH groups (forming controlled hydrogen bonds with F(-)) of BACCA led to tremendous efficiency in SN2 fluorination of base-sensitive substrates. PMID:26880350

  13. Bis-tert-Alcohol-Functionalized Crown-6-Calix[4]arene: An Organic Promoter for Nucleophilic Fluorination.

    PubMed

    Jadhav, Vinod H; Choi, Wonsil; Lee, Sung-Sik; Lee, Sungyul; Kim, Dong Wook

    2016-03-18

    A bis-tert-alcohol-functionalized crown-6-calix[4]arene (BACCA) was designed and prepared as a multifunctional organic promoter for nucleophilic fluorinations with CsF. By formation of a CsF/BACCA complex, BACCA could release a significantly active and selective fluoride source for SN2 fluorination reactions. The origin of the promoting effects of BACCA was studied by quantum chemical methods. The role of BACCA was revealed to be separation of the metal fluoride to a large distance (>8 Å), thereby producing an essentially "free" F(-). The synergistic actions of the crown-6-calix[4]arene subunit (whose O atoms coordinate the counter-cation Cs(+)) and the terminal tert-alcohol OH groups (forming controlled hydrogen bonds with F(-)) of BACCA led to tremendous efficiency in SN2 fluorination of base-sensitive substrates.

  14. Conjugation, immunoreactivity, and immunogenicity of calix[4]arenes; model study to potential calix[4]arene-based Ac3+ chelators.

    PubMed

    Grote Gansey, M H; de Haan, A S; Bos, E S; Verboom, W; Reinhoudt, D N

    1999-01-01

    For the development of calix[4]arene-based radiotherapeutic agents, the conjugation to biomolecules and immunogenicity in mice of potential 225Ac3+-chelating calix[4]arenes were studied. A calix[4]arene triethyl ester isothiocyanate and a bis(calix[4]arene) hexacarboxylic acid, containing a masked thiol functionality, were used in conjugation experiments to a mouse monoclonal antibody and serum albumins. All characterization techniques indicate that only the calix[4]arene carboxylic acid is successfully conjugated to the biomolecules. The immunoreactivity of the conjugates is not impaired when up to 6 equiv of calixarene are bound to the monoclonal antibody. Animal tests indicated that the immunogenicity toward the calix[4]arene is strongly influenced by the nature of the carrier, the dosage, and the injection method. No immune response occurred when a homologous carrier was used or when a heterologous carrier was applied at a dosage of 10 microg per immunization via intravenous injection. Under all other conditions, the presence of antibodies directed against the calix[4]arene was demonstrated. Thus, for the application in radioimmunotherapy, the conjugation of a calix[4]arene to a humanized antibody will probably not lead to an immune response, and the immunoreactivity will not be disturbed.

  15. Studies of aluminum (III) ion-selective optical sensor based on a chromogenic calix[4]arene derivative.

    PubMed

    Echabaane, M; Rouis, A; Bonnamour, I; Ben Ouada, H

    2013-11-01

    An optical chemical sensor based on azo-calix[4]arene derivative is developed for the determination of aluminum (III) ions in aqueous solutions. The complex formation ability of azo-calix[4]arene toward metal cations such as Li(I), Cs(I), K(I), Sn(II), Pb(II), Cu(II), Eu(III), Er(III) and Al(III) is investigated by UV-vis spectroscopy. Assessments of results reveal that the azo-calix[4]arene derivative has high affinity to Al(III). The stoichiometric ratio and the association constant were determined as 1:1 and 1.24×10(4)M(-1), respectively for the complex between Al(3+) and the azo-calix[4]arene. The sensing film is fabricated by spin coating on glass plates. Under the optimized conditions, at pH 6.8, the proposed optical sensor displays a linear response to Al(3+) over 10(-7) to 10(-5)M range with response time of 12min. The optical sensor can be regenerated with HNO3 solution. In addition to its high stability and reproducibility, the sensor shows good selectivity for Al(3+) ion.

  16. Studies of aluminum (III) ion-selective optical sensor based on a chromogenic calix[4]arene derivative

    NASA Astrophysics Data System (ADS)

    Echabaane, M.; Rouis, A.; Bonnamour, I.; Ben Ouada, H.

    2013-11-01

    An optical chemical sensor based on azo-calix[4]arene derivative is developed for the determination of aluminum (III) ions in aqueous solutions. The complex formation ability of azo-calix[4]arene toward metal cations such as Li(I), Cs(I), K(I), Sn(II), Pb(II), Cu(II), Eu(III), Er(III) and Al(III) is investigated by UV-vis spectroscopy. Assessments of results reveal that the azo-calix[4]arene derivative has high affinity to Al(III). The stoichiometric ratio and the association constant were determined as 1:1 and 1.24 × 104 M-1, respectively for the complex between Al3+ and the azo-calix[4]arene. The sensing film is fabricated by spin coating on glass plates. Under the optimized conditions, at pH 6.8, the proposed optical sensor displays a linear response to Al3+ over 10-7 to 10-5 M range with response time of 12 min. The optical sensor can be regenerated with HNO3 solution. In addition to its high stability and reproducibility, the sensor shows good selectivity for Al3+ ion.

  17. Synthesis, Physicochemical Studies, Molecular Dynamics Simulations, and Metal-Ion-Dependent Antiproliferative and Antiangiogenic Properties of Cone ICL670-Substituted Calix[4]arenes

    PubMed Central

    Rouge, Pascal; Dassonville-Klimpt, Alexandra; Cézard, Christine; Boudesocque, Stéphanie; Ourouda, Roger; Amant, Carole; Gaboriau, François; Forfar, Isabelle; Guillon, Jean; Guillon, Emmanuel; Vanquelef, Enguerran; Cieplak, Piotr; Dupradeau, François-Yves; Dupont, Laurent

    2014-01-01

    Iron chelators, through their capacity to modulate the iron concentration in cells, are promising molecules for cancer chemotherapy. Chelators with high lipophilicity easily enter into cells and deplete the iron intracellular pool. Consequently, iron-dependent enzymes, such as ribonucleotide reductase, which is over-expressed in cancer cells, become nonfunctional. A series of calix[4]arene derivatives substituted at the lower rim by ICL670, a strong FeIII chelator, have been synthesized. Physicochemical properties and antiproliferative, angiogenesis, and tumorigenesis effects of two calix[4]arenes mono- (5a) or disubstituted (5b) with ICL670 have been studied. These compounds form metal complexes in a ratio of one to two ligands per FeIII atom as shown by combined analyses of the protometric titration curves and ESIMS spectra. The grafting of an ICL670 group on a calix[4]arene core does not significantly alter the acid–base properties, but improves the iron-chelating and lipophilicity properties. The best antiproliferative and anti-angiogenic results were obtained with calix[4]arene ligand 5a, which possesses the highest corresponding properties. Analyses of molecular dynamics simulations performed on the two calix[4]arenes provide three-dimensional structures of the complexes and proved 5a to be the most stable upon complexation. PMID:25599014

  18. The role of arene-arene interactions in the folding of ortho-phenylenes.

    PubMed

    Mathew, Sanyo M; Engle, James T; Ziegler, Christopher J; Hartley, C Scott

    2013-05-01

    The ortho-phenylenes are a simple class of helical oligomers and representative of the broader class of sterically congested polyphenylenes. Recent work has shown that o-phenylenes fold into well-defined helical conformations (in solution and, typically, in the solid state); however, the specific causes of this folding behavior have not been determined. Here, we report the effect of substituents on the conformational distributions of a series of o-phenylene hexamers. These experiments are complemented by dispersion-corrected DFT calculations on model oligomers (B97-D/TZV(2d,2p)). The results are consistent with a deterministic role for offset arene-arene stacking interactions on the folding behavior. On the basis of the experimental and computational results, we propose a model for o-phenylene folding with two simple rules. (1) Conformers are forbidden if they include a particular sequence of biaryl torsional states that causes excessive steric strain. These "ABA" states correspond to consecutive dihedral angles of -55°/+130°/-55° (or +55°/-130°/+55). (2) The stability of the remaining conformers is determined by offset arene-arene stacking interactions that are easily estimated as an additive function of the number of well-folded torsional states (±55°) along the backbone. For the parent, unsubstituted poly(o-phenylene), each interaction contributes roughly 0.5 kcal/mol to the helix stability (in chloroform), although their strength is sensitive to substituent effects. The behavior of the o-phenylenes as a class is discussed in the context of this model. They are analogous to α-helices, with axial aromatic stacking interactions in place of hydrogen bonding. The model predicts that the overall folding propensity should be quite sensitive to relatively small changes in the strength of the arene-arene stacking. In a broader sense, these results demonstrate that polyphenylenes may exhibit folding behavior that is amenable to simple models, and validate the use

  19. Pillar[5]arene-mediated synthesis of gold nanoparticles: size control and sensing capabilities.

    PubMed

    Montes-García, Verónica; Fernández-López, Cristina; Gómez, Borja; Pérez-Juste, Ignacio; García-Río, Luis; Liz-Marzán, Luis M; Pérez-Juste, Jorge; Pastoriza-Santos, Isabel

    2014-07-01

    We present a simple procedure for the synthesis of quasi-spherical Au nanoparticles in a wide size range mediated by macrocyclic host molecules, ammonium pillar[5]arene (AP[5]A). The strategy is based on a seeded growth process in which the water-soluble pillar[5]arene undergoes complexation of the Au salt through the ammonium groups, thereby avoiding Au nucleation, while acting as a stabilizer. The presence of the pillar[5]arene onto the Au nanoparticle particle surface is demonstrated by surface-enhanced Raman scattering (SERS) spectroscopy, and the most probable conformation of the molecule when adsorbed on the Au nanoparticles surface is suggested on the basis of theoretical calculations. In addition, we analyze the host-guest interactions of the AP[5]A with 2-naphthoic acid (2NA) by using (1)H NMR spectroscopy and the results are compared with theoretical calculations. Finally, the promising synergetic effects of combining supramolecular chemistry and metal nanoparticles are demonstrated through SERS detection in water of 2NA and a polycyclic aromatic hydrocarbon, pyrene (PYR).

  20. Synthesis and Molecular Recognition of Water-Soluble S6-Corona[3]arene[3]pyridazines.

    PubMed

    Guo, Qing-Hui; Zhao, Liang; Wang, Mei-Xiang

    2015-07-13

    We report the efficient and scalable synthesis and molecular-recognition properties of novel and water-soluble S6-corona[3]arene[3]pyridazines. The synthesis comprises a one-pot nucleophilic aromatic substitution reaction between diesters of 2,5-dimercaptoterephthalate and 3,6-dichlorotetrazine followed by the inverse electron-demand Diels-Alder reaction of the tetrazine moieties with an enamine and exhaustive saponification of esters. The resulting S6-corona[3]arene[3]pyridazines, which adopt a 1,3,5-alternate conformation in the crystalline state, are able to selectively form stable 1:1 complexes with dicationic guest species in water with association constants ranging from (1.10±0.06)×10(3)  M(-1) to (1.18±0.06)×10(5)  M(-1). The easy availability, large cavity size, strong and selective binding power render the water-soluble S6-corona[3]arene[3]pyridazines useful macrocyclic hosts in various disciplines of supramolecular chemistry.

  1. Azacalix[7]arene heptamethyl ether: preparation, nanochannel crystal structure, and selective adsorption of carbon dioxide.

    PubMed

    Tsue, Hirohito; Matsui, Kazuhiro; Ishibashi, Koichi; Takahashi, Hiroki; Tokita, Satoshi; Ono, Kohei; Tamura, Rui

    2008-10-01

    To investigate the solid-state complexation of nitrogen-bridged calixarene analogues, azacalix[7]arene heptamethyl ether 1 has been prepared by applying a "5 + 2"-fragment coupling approach using Buchwald-Hartwig aryl amination reaction aided by our previously devised temporal N-silylation protocol. X-ray crystallographic analysis revealed that azacalix[7]arene 1 adopted a highly distorted 1,2-alternate conformation in the solid state as a result of intramolecular NH/O hydrogen bonding interactions and steric repulsion between the methoxy groups. In the crystal, molecules of 1 are mutually interacted by intermolecular NH/O and CH/pi interactions to establish one-dimensional (1D) hexane-filled nanochannel crystal architecture. Similarly to our recently reported azacalix[6]arene 2, the desolvated crystalline powder material of 1 was capable of selectively and rapidly adsorbing CO2 among the four main components of the atmosphere. The adsorption capacity of 1 for CO2 nearly doubled as compared to that of 2 because of the formation of the 1D nanochannel with almost twice the volume of the latter.

  2. Eruptive History of Arenal Volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Soto, G. J.; Alvarado, G. E.

    2004-12-01

    Tephra-stratigraphy, volcanic history, eruption types, eruptive dynamics and area distribution of tephra from the most important eruptions of Arenal volcano, are reviewed and updated. Deposits of explosive eruptions are named AR-1 to AR-22 (from older to younger). All previous and new Arenal and neighbouring Chato volcanoes' radiocarbon dates were calibrated: the last Chato eruption occurred 3720±150 B.P and the first known eruption of Arenal (AR-1), 7010+170-130 B.P. Isopachs and characteristics of the most relevant and recognized airfall deposits are presented. Area distributions of the key layers are oriented toward W, WSW and SW, except the lowest layer of AR-17, which is distributed northward. According to lithic isopleths, an eruption column height of 23 km (subplinian) was calculated for AR-20. Most fall layers in Arenal show associated pyroclastic flow deposits up to a distance of 6.5 km from the summit. They are restricted to river valley paths. Among Arenal eruptions, plinian-subplinian type events like AR-20, AR-15, AR-12 and AR-9, are the most violent and destructive, with tephra volumes between 0.2 and 1 km3. There are also violent strombolian eruptions which were sustained for a considerable time, resembling subplinian eruptions (the AR-19 case, total volume 0.45 km3), and pelean type eruptions, as AR-22, which erupted 0.026 km3 of tephra. A temporal correlation of explosive events after AR-8 shows that the four most important dacitic eruptions (AR-20, 15, 12 and 9), are separated by an average period of 800 years ("long term"). Three of them (AR-20, 15 and 9) have been preceded by two important explosive events with a more basic chemistry, which occurred around 300 years or less previously to the dacitic eruption ("short term" periods). Nevertheless, between cycles AR-13/14/15 and AR-18/19/20, there are two events (AR-16 and 17) that do not belong to any cycle. In fact, between the major eruptions AR-15 and 20, the highest eruptive frequency of all

  3. Structure of a piperidine-modified calix[4]arene derivative and spectral resolution of its interaction with rare earth metals with chemometric methods.

    PubMed

    Wang, Li; Wang, Xiaoya; Wang, Yanmei

    2013-03-15

    A piperidine-modified calix[4]arene derivative was synthesized and its structure was confirmed with X-ray diffraction data. UV-visible spectroscopy was used to study its molecular recognition of rare earth ions. The results revealed the calix[4]arene derivative could separate tight metal picrate ion pairs by complexation with the rare earth metal ions in tetrahydrofuran. Resolution of the UV-visible spectra with chemometric methods revealed that the derivative and the rare earth ions Eu(3+), Dy(3+), and Tb(3+) formed ML(2) complexes with stability constants of 10(8.26), 10(8.29), and 10(7.41) respectively.

  4. Structure and conformational equilibrium of new thiacalix[4]arene derivatives

    NASA Astrophysics Data System (ADS)

    Suwattanamala, A.; Magalhães, A. L.; Gomes, J. A. N. F.

    2004-02-01

    Density functional theory was used to study the structure and conformational equilibrium of tetraaminothiacalix[4]arene ( 1) and tetramercaptothiacalix[4]arene ( 2), which are expected to open a new area of host-guest chemistry. All the calculations predict the cone as the most stable conformer for both compounds, which is in good agreement with an earlier theoretical study on the parent thiacalix[4]arene. It is shown that different substituents at the lower rim do not affect the stability ordering. The intramolecular bonding between hydrogen atoms and sulfur bridges seems to be a dominant factor in stabilizing all the conformers rather than hydrogen bonds between the groups of the lower rim.

  5. Multiclausal Utterances Aren't Just for Big Kids: A Framework for Analysis of Complex Syntax Production in Spoken Language of Preschool- and Early School-Age Children

    ERIC Educational Resources Information Center

    Arndt, Karen Barako; Schuele, C. Melanie

    2013-01-01

    Complex syntax production emerges shortly after the emergence of two-word combinations in oral language and continues to develop through the school-age years. This article defines a framework for the analysis of complex syntax in the spontaneous language of preschool- and early school-age children. The purpose of this article is to provide…

  6. Selective binding of group IIIA and lanthanide metals by hexahomotrioxacalix[3]arene macrocycles

    SciTech Connect

    Daitch, C.E.; Alam, T.M.; Hampton, P.D.; Duesler, E.N.

    1996-08-21

    The hexahomotrioxacalix[3]arene macrocycles 1 are observed to bind trivalent metals (SC{sup 3+}, Lu{sup 3+}, Y{sup 3+}, La{sup 3+}) more strongly than alkali metal ions (Li{sup +}, Na{sup +}, K{sup +}). Complexes of macrocycle 1a with Lu(III) (3), Y(III) (4), and La(III) (5) have been structurally characterized to be {mu}-aryloxo-bridged dimers with the formula [M(L)(DMS0)]{sub 2} (M = Lu, Y, La; L = trianion of macrocycle 1a). Periodic trends in the structures and dynamic behavior of the complexes are discussed. 28 refs., 2 figs., 2 tabs.

  7. Selective hetero-trisfunctionalization of the large rim of a biomimetic calix[6]arene using host-guest chemistry as a synthetic tool.

    PubMed

    Colasson, Benoit; Reinaud, Olivia

    2008-11-19

    A calix[6]arene has been selectively functionalized by three different groups at the large rim. The strategy relies on the hostguest recognition chemistry of a biomimetic metal complex at the small rim (so-called "funnel complex") and the Huisgen cycloaddition. The intramolecular thermal reaction proceeds with a high efficiency, chemio- and regioselectivity, allowing the monofunctionalization of one aromatic unit among three. Thanks to the high yield and selectivity of the reaction, it can be applied successively twice on the same compound, which opens the route for inherently chiral calix[6]arenes. This methodology not only is of wide potential for obtaining and exploiting calix[6]arenes that are dissymmetrized at the large rim, but also stands as an exemplary strategy for the selective appending of a functional group on a host platform.

  8. Intramolecular transfer of {open_quotes}CO{close_quotes} from ({eta}{sup 6}-arene)Cr(CO){sub 3} complexes in stille-type palladium-catalyzed cross coupling reactions

    SciTech Connect

    Caldirola, P.; Chowdhury, R.; Johansson, A.M.; Hacksell, U.

    1995-12-31

    The reaction between [{eta}{sup 6}-(trialkylstannyl)benzene]Cr(CO){sub 3} complexes and different electrophiles such as iodobenzene and aryltriflate and the coupling between (tributylphenyl)stannane and the Cr(CO){sub 3} complex of chlorobenzene have been studied. Products from two different types of reactions were observed: (1) benzophenone along with the alkylarylketone, resulting from a carbonylative coupling, and (2) biphenyl, arising from a direct coupling.

  9. The contrasting activity of iodido versus chlorido ruthenium and osmium arene azo- and imino-pyridine anticancer complexes: control of cell selectivity, cross-resistance, p53 dependence, and apoptosis pathway.

    PubMed

    Romero-Canelón, Isolda; Salassa, Luca; Sadler, Peter J

    2013-02-14

    Organometallic half-sandwich complexes [M(p-cymene)(azo/imino-pyridine)X](+) where M = Ru(II) or Os(II) and X ═ Cl or I, exhibit potent antiproliferative activity toward a range of cancer cells. Not only are the iodido complexes more potent than the chlorido analogues, but they are not cross-resistant with the clinical platinum drugs cisplatin and oxaliplatin. They are also more selective for cancer cells versus normal cells (fibroblasts) and show high accumulation in cell membranes. They arrest cell growth in G1 phase in contrast to cisplatin (S phase) with a high incidence of late-stage apoptosis. The iodido complexes retain potency in p53 mutant colon cells. All complexes activate caspase 3. In general, antiproliferative activity is greatly enhanced by low levels of the glutathione synthase inhibitor l-buthionine sulfoxime. The work illustrates how subtle changes to the design of low-spin d(6) metal complexes can lead to major changes in cellular metabolism and to potent complexes with novel mechanisms of anticancer activity.

  10. 31 Million Older Americans Aren't Getting Enough Exercise

    MedlinePlus

    ... 31 Million Older Americans Aren't Getting Enough Exercise Inactivity boosts their risk for falls, broken bones, ... one-quarter of Americans over 50 don't exercise, a new federal report estimates, increasing their risk ...

  11. Annelation of furan rings to arenes

    NASA Astrophysics Data System (ADS)

    Omelchuk, O. A.; Tikhomirov, A. S.; Shchekotikhin, A. E.

    2016-08-01

    Benzo[b]furans have been used in various fields of chemistry and technology due to their unique physical, chemical and biological properties. It is primarily a wide range of biological activities of natural and synthetic benzo[b]furan derivatives and their polyfused analogues (naphthofurans, anthrafurans, etc.) that attracts a significant scientific interest in the context of using these heterocycles as privileged scaffolds in drug design. This survey covers those methods for the annelation of a furan ring to arenes that have been developed mostly during the last decade. We also analyze trends in synthetic methods of benzo[b]furans. Some synthetic schemes are highly efficient in the synthesis of polyfunctionalized furan derivatives. The bibliography includes 110 references.

  12. Osmium(II)--versus ruthenium(II)--arene carbohydrate-based anticancer compounds: similarities and differences.

    PubMed

    Hanif, Muhammad; Nazarov, Alexey A; Hartinger, Christian G; Kandioller, Wolfgang; Jakupec, Michael A; Arion, Vladimir B; Dyson, Paul J; Keppler, Bernhard K

    2010-08-21

    The synthesis and in vitro anticancer activity of Os(II)-arene complexes with carbohydrate-derived phosphite co-ligands are reported. The compounds were characterized by standard methods and the molecular structure of dichlorido(eta(6)-p-cymene)(3,5,6-bicyclophosphite-1,2-O-isopropylidene-alpha-D-glucofuranoside)osmium(II) was determined by X-ray diffraction analysis. Complexes with chlorido leaving groups undergo hydrolysis by consecutive formation of aqua compounds, followed by cleavage of a P-O bond of sugar phosphite ligands, as demonstrated by NMR studies. These observations are similar to those of analogous Ru(II)-arene complexes; however the rate of hydrolysis is very slow for osmium compounds. The complexes with oxalato leaving groups resist hydrolysis; no hydrolytic species were detected by (31)P{(1)H} NMR spectroscopy over several days. Within this series of Os compounds, in vitro anticancer activity is highest for the most lipophilic chlorido complex dichlorido(eta(6)-p-cymene)(3,5,6-bicyclophosphite-1,2-O-cyclohexylidene-alpha-D-glucofuranoside)osmium(II).

  13. Experimental study into the petrogenesis of crystal-rich basaltic to andesitic magmas at Arenal volcano

    NASA Astrophysics Data System (ADS)

    Parat, F.; Streck, M. J.; Holtz, F.; Almeev, R.

    2014-08-01

    Arenal volcano is nearly unique among arc volcanoes with its 42 year long (1968-2010) continuous, small-scale activity erupting compositionally monotonous basaltic andesites that also dominate the entire, ~7000 year long, eruptive history. Only mineral zoning records reveal that basaltic andesites are the result of complex, open-system processes deriving minerals from a variety of crystallization environments and including the episodic injections of basalt. The condition of the mafic input as well as the generation of crystal-rich basaltic andesites of the recent, 1968-2010, and earlier eruptions were addressed by an experimental study at 200 MPa, 900-1,050 °C, oxidizing and fluid-saturated conditions with various fluid compositions [H2O/(H2O + CO2) = 0.3-1]. Phase equilibria were determined using a phenocryst-poor (~3 vol%) Arenal-like basalt (50.5-wt% SiO2) from a nearby scoria cone containing olivine (Fo92), plagioclase (An86), clinopyroxene (Mg# = 82) and magnetite (Xulvö = 0.13). Experimental melts generally reproduce observed compositional trends among Arenal samples. Small differences between experimental melts and natural rocks can be explained by open-system processes. At low pressure (200 MPa), the mineral assemblage as well as the mineral compositions of the natural basalt were reproduced at 1,000 °C and high water activity. The residual melt at these conditions is basaltic andesitic (55 wt% SiO2) with 5 wt% H2O. The evolution to more evolved magmas observed at Arenal occurred under fluid-saturated conditions but variable fluid compositions. At 1,000 °C and 200 MPa, a decrease of water content by approximately 1 wt% induces significant changes of the mineral assemblage from olivine + clinopyroxene + plagioclase (5 wt% H2O in the melt) to clinopyroxene + plagioclase + orthopyroxene (4 wt% H2O in the melt). Both assemblages are observed in crystal-rich basalt (15 vol%) and basaltic andesites. Experimental data indicate that the lack of orthopyroxene

  14. 10-π-Electron arenes à la carte: structure and bonding of the [E-(CnHn)-E](n-6) (E = Ca, Sr, Ba; n = 6-8) complexes.

    PubMed

    Mondal, Sukanta; Cabellos, Jose Luis; Pan, Sudip; Osorio, Edison; Torres-Vega, Juan Jose; Tiznado, William; Restrepo, Albeiro; Merino, Gabriel

    2016-04-28

    In this paper, we provide solid evidence to show that among an overwhelming structural diversity, alkaline earth metals (Ca, Sr, Ba) have the ability to form inverted sandwich compounds with C6H6, C7H7(+), and C8H8(2+) of Dnh symmetry and general formula [E-(CnHn)-E](n-6) (n = 6-8) with planar 10-π-electron aromatic cores by virtue of transferring two electrons per metal atom to the ring. However, the origin of the orbital interaction between the metals and the carbon ring is quite different; while [E-(C6H6)-E] complexes are dominated by δ-interactions, both π- and δ-interactions are important in [E-(C7H7)-E](+) and [E-(C8H8)-E](2+) complexes. PMID:26936126

  15. [The Ion Identification and Molecular Logic Gate of a Thiacalix[4]arene Fluorescent Probe].

    PubMed

    Wu, Fu-yong; Yu, Mei; Mu, Lan; Zeng, Xi; Wang, Rui-xiao; Takehiko Yamato

    2016-01-01

    A disubstituted phthalimide-based thiacalix[4] arene derivative (probe s1) was synthesized from cone 1, 3-thiacalix[4] arene and hydroxyethyl phthalimide, with benzyl appended the lower edge of thiacalix[4]-arene by triazole ring in the 2,4 position. The relative fluorescence quantum yield of probe s1 is 0.43 in CH3CN solvent. The strong fluorescence emission of probe s1 at 390 nm wavelength can be selectively quenched by Fe3+ in DMF/H2O solution. Similarly, the presence of I- also induced a significant fluorescence quenching of probe s1 at 310 nm wavelength in CH3CN solution. Spectral titration and isothermal titration calorimetry were showed that probe s1 with Fe3+ or I- both form 1 : 1 complexes, the binding constants up to 10(5) and coordinate process were spontaneous. The linear ranges of fluorescence detect Fe3+ or I- were 1.0 x 10(-7) - 1.6 x 10(-4) mol x L(-1) and 1.0 x 10(-7) - 8.5 x 10(-5) mol x L(-1), detection limits were up to 2.30 x 10(-8) mol x L(-1) and 1.17 x 10(-8) mol x L(-1), respectively. Meanwhile, take advantage of identification and coordination action, a logic circuit constructed at the molecular level by controlling two input signals of Fe3+ and F-, which causing probe s1 cycling of fluorescence emission or quenching. IR spectrum speculated that the nitrogen atoms of triazole groups are involved in the complexation with Fe3+, while the hydrogen atoms of triazole groups were complexed with I- by hydrogen bonding. PMID:27228760

  16. New method for predicting melting points of polynitro arene and polynitro heteroarene compounds.

    PubMed

    Keshavarz, Mohammad Hossein

    2009-11-15

    This work introduces a new method for prediction of melting points of nitroaromatic compounds, including polynitro arenes and polynitro heteroarenes, through their molecular structures. The new model extends earlier work, which was used for carbocyclic nitroaromatic compounds, to estimate melting points of heterocyclic aromatic compounds. Some specific functional groups and structural parameters can be used to improve the predicted values on the basis of the number of carbon, hydrogen and nitrogen atoms. The predicted results show that this method gives reliable prediction of melting points with respect to previous work and well-developed group additivity methods for different nitroaromatic explosives with complex molecular structures.

  17. Olefin Metathesis With Ruthenium-Arene Catalysts Bearing N-Heterocyclic Carbene Ligands

    NASA Astrophysics Data System (ADS)

    Delaude, Lionel; Demonceau, Albert

    In this chapter, we summarize the main results of our investigations on the ring-opening metathesis polymerization (ROMP) of cyclooctene catalyzed by various ruthenium (Ru)-arene complexes bearing imidazolin-2-ylidene, imidazolidin- 2-ylidene, or triazolin-5-ylidene ligands. Three major findings emerged from this study. First, we underscored the intervention of a photochemical activation step due to visible light illumination. Second, we established that the presence of an endocyclic double bond in the carbene ligand central heterocycle was not crucial to achieve high catalytic efficiencies. Third, we demonstrated that ortho-metallation of the N-heterocyclic carbene (NHC) ligand by the Ru center led to inactive catalysts.

  18. Direct Synthesis of Polyaryls by Consecutive Oxidative Cross-Coupling of Phenols with Arenes.

    PubMed

    Dyadyuk, Alina; Sudheendran, Kavitha; Vainer, Yulia; Vershinin, Vlada; Shames, Alexander I; Pappo, Doron

    2016-09-01

    A bioinspired iron-catalyzed consecutive oxidative cross-coupling reaction between a single phenolic unit and nucleophilic arenes was developed. This sustainable transformation offers a selective synthetic strategy for the preparation of complex polyaryl compounds directly from readily available phenols. With the aid of electron paramagnetic resonance spectroscopy, it was demonstrated that the groups ortho to the phenolic functionality (whether hydrogen, methyl, or methoxy) direct the regioselectivity (ortho, para, or meta via dienone-phenol rearrangement) and chemoselectivity (C-C coupling or C-O coupling) in this multistep process. PMID:27529128

  19. Synergistic extraction of some univalent cations into nitrobenzene by using cesium dicarbollylcobaltate and calix[4]arene-...

    SciTech Connect

    Makrlik, Emanuel; Selucky, P.; Vanura, Petr; Moyer, Bruce A

    2013-01-01

    From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+ (aq) + CsL+ (nb) , ML+ (nb) + Cs+ (aq) taking place in the two-phase water nitrobenzene system (M+ = K+, Rb+, NH+4,Ag+, Tl+; L = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML+ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: NH+4 < K+ < Ag+ < Rb+ < Tl+.

  20. GSH- and pH-responsive drug delivery system constructed by water-soluble pillar[5]arene and lysine derivative for controllable drug release.

    PubMed

    Wu, Xuan; Li, Yan; Lin, Chen; Hu, Xiao-Yu; Wang, Leyong

    2015-04-21

    Novel GSH- and pH-responsive supramolecular vesicles constructed by an amphiphilic inclusion complex formed from water-soluble pillar[5]arene and lysine derivative have been successfully developed, which can efficiently encapsulate anticancer drug MTZ and show rapid MTZ-release in a simulated acidic tumor environment with high GSH concentration, and exhibit potent antitumor activity.

  1. Negative ion gas-phase chemistry of arenes.

    PubMed

    Danikiewicz, Witold; Zimnicka, Magdalena

    2016-01-01

    Reactions of aromatic and heteroaromatic compounds involving anions are of great importance in organic synthesis. Some of these reactions have been studied in the gas phase and are occasionally mentioned in reviews devoted to gas-phase negative ion chemistry, but no reviews exist that collect all existing information about these reactions. This work is intended to fill this gap. In the first part of this review, methods for generating arene anions in the gas phase and studying their physicochemical properties and fragmentation reactions are presented. The main topics in this part are as follows: processes in which gas-phase arene anions are formed, measurements and calculations of the proton affinities of arene anions, proton exchange reactions, and fragmentation processes of substituted arene anions, especially phenide ions. The second part is devoted to gas-phase reactions of arene anions. The most important of these are reactions with electrophiles such as carbonyl compounds and α,β-unsaturated carbonyl and related compounds (Michael acceptors). Other reactions including oxidation of arene anions and halogenophilic reactions are also presented. In the last part of the review, reactions of electrophilic arenes with nucleophiles are discussed. The best known of these is the aromatic nucleophilic substitution (SN Ar) reaction; however, other processes that lead to the substitution of a hydrogen atom in the aromatic ring are also very important. Aromatic substrates in these reactions are usually but not always nitroarenes bearing other substituents in the ring. The first step in these reactions is the formation of an anionic σ-adduct, which, depending on the substituents in the aromatic ring and the structure of the attacking nucleophile, is either an intermediate or a transition state in the reaction path. In the present review, we attempted to collect the results of both experimental and computational studies of the aforementioned reactions conducted since the

  2. Symmetrically tetrasubstituted p-nitrocalix[4]arenes: Synthesis, spectra and crystal structures

    NASA Astrophysics Data System (ADS)

    Klimentová, Jana; Vojtíšek, Pavel; Sklenářová, Markéta

    2007-12-01

    Symmetrically tetrasubstituted p-nitrocalix[4]arenes are not only important chemical intermediates in calix[4]arene synthesis; these molecules possess important physical properties as well. In this article, synthesis, crystal structures, FTIR, FT Raman and UV-vis spectra for several p-nitrocalix[4]arenes are reported.

  3. Cross-linked supramolecular polymer gels constructed from discrete multi-pillar[5]arene metallacycles and their multiple stimuli-responsive behavior.

    PubMed

    Li, Zhong-Yu; Zhang, Yanyan; Zhang, Chang-Wei; Chen, Li-Jun; Wang, Chao; Tan, Hongwei; Yu, Yihua; Li, Xiaopeng; Yang, Hai-Bo

    2014-06-18

    A new family of discrete hexakis-pillar[5]arene metallacycles with different sizes have been successfully prepared via coordination-driven self-assembly, which presented very few successful examples of preparation of discrete multiple pillar[n]arene derivatives. These newly designed hexakis-pillar[5]arene metallacycles were well characterized with one-dimensional (1-D) multinuclear NMR ((1)H and (31) P NMR), two-dimensional (2-D) (1)H-(1)H COSY and NOESY, ESI-TOF-MS, elemental analysis, and PM6 semiempirical molecular orbital methods. Furthermore, the host-guest complexation of such hexakis-pillar[5]arene hosts with a series of different neutral ditopic guests G1-6 were well investigated. Through host-guest interactions of hexakis-pillar[5]arene metallacycles H2 or H3 with the neutral dinitrile guest G5, the cross-linked supramolecular polymers H2⊃(G5)3 or H3⊃(G5)3 were successfully constructed at the high-concentration region, respectively. Interestingly, these cross-linked supramolecular polymers transformed into the stable supramolecular gels upon increasing the concentrations to a relatively high level. More importantly, by taking advantage of the dynamic nature of metal-ligand bonds and host-guest interactions, the reversible multiple stimuli-responsive gel-sol phase transitions of such polymer gels were successfully realized under different stimuli, such as temperature, halide, and competitive guest, etc. The mechanism of such multiple stimuli-responsive processes was well illustrated by in situ multinuclear NMR investigation. This research not only provides a highly efficient approach to the preparation of discrete multiple pillar[n]arene derivatives but also presents a new family of multiple stimuli-responsive "smart" soft matters.

  4. Membrane composites derived from porous versus nonporous surfactants. Evidence for uniqueness of calix[6]arene-based surfactants

    SciTech Connect

    Lee, W.; Hendel, R.A.; Dedek, P.; Janout, V.; Regen, S.L.

    1995-06-28

    In this paper we provide evidence for uniqueness of calix[6]arene surfactants as building blocks for the construction of permeation-selective composites. Specifically, we show that membranes made from poly[1-(trimethylsilyl)-1-propyne] (PTMSP) plus multilayers of calix[6]arene I exhibit significant permeation selectivity toward He and N{sub 2}, but that those based on arachidic acid (AA), cadmium arachidate (AA/Cd{sup 2+}), a polyion complex of AA plus poly(ethyleneimine) (AA-PEI), and stearamide oxime (SA) show no permeation selectivity and no alteration in the barrier properties of the support. We also report results of surface analyses of PTMSP/I and PTMSP/SA by X-ray photoelectron spectroscopy (XPS) that offer insight into the origin of these striking differences. 40 refs., 2 figs., 1 tab.

  5. Thiacalix[4]arene: New protection for metal nanoclusters

    PubMed Central

    Guan, Zong-Jie; Zeng, Jiu-Lian; Nan, Zi-Ang; Wan, Xian-Kai; Lin, Yu-Mei; Wang, Quan-Ming

    2016-01-01

    Surface organic ligands are critical for the formation and properties of atomically precise metal nanoclusters. In contrast to the conventionally used protective ligands such as thiolates and phosphines, thiacalix[4]arene has been used in the synthesis of a silver nanocluster, [Ag35(H2L)2(L)(C≡CBut)16](SbF6)3, (H4L, p-tert-butylthiacalix[4]-arene). This is the first structurally determined calixarene-protected metal nanocluster. The chelating and macrocyclic effects make the thiacalix[4]arene a rigid shell that protects the silver core. Upon addition or removal of one silver atom, the Ag35 cluster can be transformed to Ag36 or Ag34 species, and the optical properties are changed accordingly. The successful use of thiacalixarene in the synthesis of well-defined silver nanoclusters suggests a bright future for metal nanoclusters protected by macrocyclic ligands. PMID:27536724

  6. Activation-Enabled Syntheses of Functionalized Pillar[5]arene Derivatives.

    PubMed

    Han, Jie; Hou, Xisen; Ke, Chenfeng; Zhang, Huacheng; Strutt, Nathan L; Stern, Charlotte L; Stoddart, J Fraser

    2015-07-01

    A series of regioselective di- and trifunctionalized pillar[5]arene derivatives have been synthesized by a deprotection-followed-by-activation strategy, and their constitutions have been established as a result of having access to their solid-state structures. De-O-methylation occurs in a stepwise manner at lower temperatures under kinetic control, affording the desired oligo-substituted pillar[5]arene derivatives. In addition, the regioisomers of these derivatives can be isolated by installing triflate groups on the free hydroxyl groups. PMID:26083303

  7. Synthesis and spectroscopic properties of zeolite-entrapped bis-heteroleptic ruthenium(II) polypyridine complexes. [Ru sup 2+ (bpy) sub 2 (bpz) sup 2+ -Y and Ru sup 2+ (bpy) sub 2 (dmb) sup 2+ -Y where bpy is bipyridine, bpz is bipyrazine, dmp is 4,4'-dimethyl-2,2'-bipyridine, and Y is zeolite

    SciTech Connect

    Maruszewski, K.; Kincaid, J.R. ); Strommen, D.P.; Handrich, K. )

    1991-11-27

    A convenient method for the preparation of polypyridine complexes of Ru(II) within the supercages of zeolite Y is reported. The bis-heteroleptic trisligated species Ru{sup 2+}(bpy){sub 2}(bpz){sup 2+}-Y and Ru{sup 2+}(bpy){sub 2}(dmb){sup 2+}-Y have been obtained and characterized by electronic absorption and resonance Raman spectroscopies. Two methods of zeolite matrix destruction have been used to extract the zeolite-entrapped complexes. Depending on experimental conditions, a blue byproduct can be formed in the zeolite supercages. Preliminary evidence suggests that this compound is properly formulated as Ru{sup 3+}(bpy){sub 2}(X)0-(where X is unspecified) bound to the supercage interior wall via an oxygen atom donated by the zeolite.

  8. Zinc(II), ruthenium(II), rhodium(III), palladium(II), silver(I), platinum(II) and MoO22+ complexes of 2-(2‧-hydroxy-5‧-methylphenyl)-benzotriazole as simple or primary ligand and 2,2‧-bipyridyl, 9,10-phenanthroline or triphenylphosphine as secondary ligands: Structure and anticancer activity

    NASA Astrophysics Data System (ADS)

    El-Asmy, Hala A.; Butler, Ian S.; Mouhri, Zhor S.; Jean-Claude, Bertrand J.; Emmam, Mohamed S.; Mostafa, Sahar I.

    2014-02-01

    New complexes of 2-(2‧-hydroxy-5‧-methylphenyl)-benzotriazole (Hhmbt), [Zn(hmbt)2(H2O)2], [Zn(hmbt)(OAc)(H2O)2], [Pd(hmbt)(H2O)Cl], [Pd(hmbt)2], [M(PPh3)(hmbt)Cl], [M(L)(hmbt)]Cl (M(II) = Pd, Pt; L = bpy, phen), [Ag2(hmbt)2], [Ag(phen)(hmbt)], [Ag(PPh3)(hmbt)], [Rh(hmbt)2(H2O)2]Cl, [Ru(hmbt)2(H2O)2], [Ru(PPh3)(hmbt)2Cl] and cis-[MoO2(hmbt)2] have been synthesized. They have been structurally and spectroscopically characterized on the basis of elemental analysis, IR, NMR (1H, 13C, 31P), UV-vis. and ESI-mass spectroscopy, thermal and molar conductivity measurements. 2-(2‧-Hydroxy-5‧-methylphenyl)-benzotriazole behaves as a mononegative bidentate through the deprotonated phenolic oxygen and imine nitrogen atoms. The reported complexes have been tested against human breast cancer (MDA-MB231) and human ovarian cancer (OVCAR-8) cell lines. The complexes, [Ag(hmpbt)(PPh3)], [Rh(hmbt)2(H2O)2]Cl, [Pt(phen)(hmbt)]Cl and [Pd(phen)(hmbt)]Cl exhibit the highest growth inhibitory activity with mean IC50 values 1.37, 7.52, 5.24 and 4.85 μM (MDA-MB231) and 1.75, 8.50, 3.00 and 2.99 μM (OVACAR-8), respectively.

  9. Improved Arene Fluorination Methodology for I(III) Salts

    PubMed Central

    Wang, Bijia; Qin, Linlin; Neumann, Kiel D.; Uppaluri, ShriHarsha; Cerny, Ronald L.; DiMagno, Stephen G.

    2010-01-01

    The use of low polarity aromatic solvents (benzene or toluene) and/or the removal of inorganic salts results in dramatically improved yields of fluorinated arenes from diaryliodonium salts. This methodology is shown to “scale down” to the conditions used typically for radiotracer synthesis. PMID:20617820

  10. Recent developments on the trifluoromethylation of (hetero)arenes.

    PubMed

    Wu, Xiao-Feng; Neumann, Helfried; Beller, Matthias

    2012-08-01

    Aryl-CF(3) as an extremely important family of fluorinated organic compounds holds wide applications in pharmaceuticals, agrochemicals, and advanced materials. Traditionally, such trifluoromethylated compounds have been synthesized from the corresponding aryl trichlorides via Cl exchange reactions (Scheme 1). This Focus review gives an overview over the recent development of trifluoromethylation of (hetero)arenes. PMID:22715145

  11. Integrated velocity field from ground and satellite geodetic techniques: application to Arenal volcano

    NASA Astrophysics Data System (ADS)

    Muller, Cyril; del Potro, Rodrigo; Biggs, Juliet; Gottsmann, Joachim; Ebmeier, Susanna K.; Guillaume, Sébastien; Cattin, Paul-Henri; Van der Laat, Rodolfo

    2015-02-01

    Measurements of ground deformation can be used to identify and interpret geophysical processes occurring at volcanoes. Most studies rely on a single geodetic technique, or fit a geophysical model to the results of multiple geodetic techniques. Here we present a methodology that combines GPS, Total Station measurements and InSAR into a single reference frame to produce an integrated 3-D geodetic velocity surface without any prior geophysical assumptions. The methodology consists of five steps: design of the network, acquisition and processing of the data, spatial integration of the measurements, time series computation and finally the integration of spatial and temporal measurements. The most significant improvements of this method are (1) the reduction of the required field time, (2) the unambiguous detection of outliers, (3) an increased measurement accuracy and (4) the construction of a 3-D geodetic velocity field. We apply this methodology to ongoing motion on Arenal's western flank. Integration of multiple measurement techniques at Arenal volcano revealed a deformation field that is more complex than that described by individual geodetic techniques, yet remains consistent with previous studies. This approach can be applied to volcano monitoring worldwide and has the potential to be extended to incorporate other geodetic techniques and to study transient deformation.

  12. New superhindered polydentate polyphosphine ligands P(CH2CH2P(t)Bu2)3, PhP(CH2CH2P(t)Bu2)2, P(CH2CH2CH2P(t)Bu2)3, and their ruthenium(II) chloride complexes.

    PubMed

    Gilbert-Wilson, Ryan; Field, Leslie D; Bhadbhade, Mohan M

    2012-03-01

    The synthesis and characterization of the extremely hindered phosphine ligands, P(CH(2)CH(2)P(t)Bu(2))(3) (P(2)P(3)(tBu), 1), PhP(CH(2)CH(2)P(t)Bu(2))(2) (PhP(2)P(2)(tBu), 2), and P(CH(2)CH(2)CH(2)P(t)Bu(2))(3) (P(3)P(3)(tBu), 3) are reported, along with the synthesis and characterization of ruthenium chloro complexes RuCl(2)(P(2)P(3)(tBu)) (4), RuCl(2)(PhP(2)P(2)(tBu)) (5), and RuCl(2)(P(3)P(3)(tBu)) (6). The bulky P(2)P(3)(tBu) (1) and P(3)P(3)(tBu) (3) ligands are the most sterically encumbered PP(3)-type ligands so far synthesized, and in all cases, only three phosphorus donors are able to bind to the metal center. Complexes RuCl(2)(PhP(2)P(2)(tBu)) (5) and RuCl(2)(P(3)P(3)(tBu)) (6) were characterized by crystallography. Low temperature solution and solid state (31)P{(1)H} NMR were used to demonstrate that the structure of RuCl(2)(P(2)P(3)(tBu)) (4) is probably analogous to that of RuCl(2)(PhP(2)P(2)(tBu)) (5) which had been structurally characterized.

  13. Unexpected formation of ruthenium(II) hydrides from a reactive dianiline precursor and 1,2-(Ph2P)2-1,2-closo-C2B10H10.

    PubMed

    Adams, Jeramie J; Del Negro, Andrew S; Arulsamy, Navamoney; Sullivan, B Patrick

    2008-03-17

    Reaction of the new precursor cis, trans-Ru(cod)(anln)2Cl2 with the diphosphine 1,2-bis(diphenylphosphino)-1,2-dicarba-closo-dodecaborane (o-dppc) unexpectedly results in two new ruthenium(II) hydrides, trans-Ru(o-dppc) 2(H)Cl and the neutral, five-coordinate complex Ru(o-dppc)(nido-dppc)(H), depending upon the reaction conditions [anln is aniline and nido-dppc is 7,8-(Ph2P)2C2B9H10(-)]. Chloride abstraction from trans-Ru(o-dppc)2(H)Cl leads to another five-coordinate hydride, [Ru(o-dppc)2(H)](+), which is isolated as either a triflate or hexafluorophosphate salt. On the basis of labeling and reactivity studies, the source of the hydride appears to be the cod ligand. PMID:18217750

  14. Geochemical stratigraphy and magmatic evolution at Arenal Volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Bolge, Louise L.; Carr, Michael J.; Feigenson, Mark D.; Alvarado, Guillermo E.

    2006-09-01

    Arenal has been active for at least the past 7000 years. Prior to 3000 years B.P. (before present), Arenal eruptive products consisted of lavas and tephras both with a mafic (basaltic andesitic) composition. At approximately 3000 years B.P. Arenal began producing two discrete tephra compositions, a mafic (basaltic) tephra and a silicic (andesitic to dacitic) tephra as well as the basaltic andesitic lavas whose composition falls into the gap between the two tephra compositions. The amount of phenocrysts in both the mafic tephras and, to a lesser extent, the lavas, has increased steadily over time, demonstrating a gradual increase in the amount of crystal-liquid fractionation. At approximately 3000 years B.P. the fractionation reached a threshold causing the production of silicic tephras in conjunction with the mafic tephras. Modal analyses show that while the mafic tephras become more crystalline over time, the silicic tephras have become glassier. These younger mafic tephras are mineral-rich residues, while the silicic tephras are the incompatible element rich melt. There is also an increase in the crystal-liquid fractionation within the magma forming the lavas and tephras. The concentration of incompatible elements in the lavas has increased over time, while it has decreased in the tephras. In addition to the crystal-liquid redistribution in the magmas at Arenal, there have also been changes in Arenal's source region. The amount of flux from the subducting slab and consequently the degree of melting increase up to approximately 3000 years B.P., and then begin decreasing.

  15. Catalytic synthesis of n-alkyl arenes through alkyl group cross-metathesis.

    PubMed

    Dobereiner, Graham E; Yuan, Jian; Schrock, Richard R; Goldman, Alan S; Hackenberg, Jason D

    2013-08-28

    n-Alkyl arenes were prepared in a one-pot tandem dehydrogenation/olefin metathesis/hydrogenation sequence directly from alkanes and ethylbenzene. Excellent selectivity was observed when ((tBu)PCP)IrH2 was paired with tungsten monoaryloxide pyrrolide complexes such as W(NAr)(C3H6)(pyr)(OHIPT) (1a) [Ar = 2,6-i-Pr2C6H3; pyr = pyrrolide; OHIPT = 2,6-(2,4,6-i-Pr3C6H2)2C6H3O]. Complex 1a was also especially active in n-octane self-metathesis, providing the highest product concentrations reported to date. The thermal stability of selected olefin metathesis catalysts allowed elevated temperatures and extended reaction times to be employed. PMID:23909821

  16. The Olefin Metathesis Reactions Combined with Organo-Iron Arene Activation Towards Dendrimers, and Polymers

    NASA Astrophysics Data System (ADS)

    Astruc, Didier; Martinez, Victor

    The subjects treated in the two lectures of the North Atlantic Treaty Organization (NATO) summer course are (1) the combination of arene activation and perfunctionalization using organo-iron chemistry with olefin metathesis incuding metathesis of dendritic polyolefin molecules; (2) the synthesis of metallodendritic benzylidene complexes that catalyse ring-opening metathesis polymerization (ROMP) under ambient conditions and the formation of dendritic stars; (3) the use of stoichiometric and catalytic electron-transfer processes with standard reservoirs of electrons (reductants) or electron holes (oxidants) iron complexes to achieve noteworthy metathesis reactions or synthesize compounds that are useful in metathesis. Only the two first topics are treated in this chapter, and interested readers can find references concerning the third aspect called in the introduction and subsequently cited in the reference list.

  17. DNA Interactions with Ruthenium(ll) Polypyridine Complexes Containing Asymmetric Ligands

    PubMed Central

    Chao, Hui

    2005-01-01

    In an attempt to probe nucleic acid structures, numerous Ru(II) complexes with different ligands have been synthesized and investigated. In this contribution we focus on the DNA-binding properties of ruthenium(II) complexes containing asymmetric ligands that have attracted little attention in the past decades. The influences of the shape and size of the ligand on the binding modes, affinity, enantioselectivities and photocleavage of the complexes to DNA are described. PMID:18365086

  18. In Vitro and in Vivo Evaluation of Water-Soluble Iminophosphorane Ruthenium(II) Compounds. A Potential Chemotherapeutic Agent for Triple Negative Breast Cancer

    PubMed Central

    2015-01-01

    A series of organometallic ruthenium(II) complexes containing iminophosphorane ligands have been synthesized and characterized. Cationic compounds with chloride as counterion are soluble in water (70–100 mg/mL). Most compounds (especially highly water-soluble 2) are more cytotoxic to a number of human cancer cell lines than cisplatin. Initial mechanistic studies indicate that the cell death type for these compounds is mainly through canonical or caspase-dependent apoptosis, nondependent on p53, and that the compounds do not interact with DNA or inhibit protease cathepsin B. In vivo experiments of 2 on MDA-MB-231 xenografts in NOD.CB17-Prkdc SCID/J mice showed an impressive tumor reduction (shrinkage) of 56% after 28 days of treatment (14 doses of 5 mg/kg every other day) with low systemic toxicity. Pharmacokinetic studies showed a quick absorption of 2 in plasma with preferential accumulation in the breast tumor tissues when compared to kidney and liver, which may explain its high efficacy in vivo. PMID:25409416

  19. Ruthenium(II) and osmium(II) mixed chelates based on pyrenyl-pyridylimidazole and 2,2'-bipyridine ligands as efficient DNA intercalators and anion sensors.

    PubMed

    Mardanya, Sourav; Karmakar, Srikanta; Maity, Dinesh; Baitalik, Sujoy

    2015-01-20

    We report herein the synthesis and characterization of two monometallic ruthenium(II) and osmium(II) complexes of composition [(bpy)2M(HImzPPy)] (ClO4)2 derived from pyrenylimidazole-10-pyridin-2-yl-9H-9,11-diazacyclopenta[e]pyrene (HImzPPy) and 2,2'-bipyridine (bpy) ligands. X-ray crystallographic study shows that both crystals belong to the triclinic system having space group P1̅. The photophysical properties of 1 and 2 in acetonitrile indicate that the metal-to-ligand charge-transfer excited state is mainly centered in the [M(bpy)2](2+) moiety of the complexes and slightly affected by the extended conjugation of the pyrenylimidazole moiety. Both complexes display one-electron reversible metal-centered oxidative processes and a number of quasi-reversible reductive processes. The binding affinities of the complexes toward calf-thymus DNA (CT-DNA) were thoroughly studied through different methods such as absorption, emission, excited-state lifetime, circular dichroism, and thermal denaturation of DNA and a relative DNA binding study using ethidium bromide. All of these experiments account for the intercalative nature of both 1 and 2 toward CT-DNA as well as their light-switch behavior. The anion recognition study through different spectroscopic techniques reveals that both complexes act as "turn-on" luminescence sensors for H2PO4(-) and "turn-off" sensors toward F(-) and AcO(-). The imidazole N-H proton of the receptors gets deprotonated with the excessive addition of F(-) and AcO(-), while it interacts with H2PO4(-) through hydrogen-bonding interaction. Theoretical calculations (DFT and TD-DFT) were also performed to understand the photophysical properties of the metalloreceptors.

  20. 1-(2-biphenyl)-3-methyltriazenide-N-oxide as a template for intramolecular copper(II)⋯arene-π interactions

    NASA Astrophysics Data System (ADS)

    Paraginski, Gustavo Luiz; Hörner, Manfredo; Back, Davi Fernando; Wohlmuth Alves dos Santos, Aline Joana Rolina; Beck, Johannes

    2016-01-01

    Deprotonated triazene N-oxides are able to chelate metal ions resulting in five-membered rings without carbon atoms. A new ligand 1-(2-biphenyl)-3-methyltriazenide-N-oxide (1) and its mononuclear Cu(II) complex (2) were synthesized to verify the capability of this ligand to promote Cu(II)⋯arene-π interactions. Ligand 1 and complex 2 have been characterized by elemental analysis, mass spectrometry (ESI(+)-TOF), IR, and UV-Vis spectroscopy. In addition, ligand 1 was characterized by 1H and 13C NMR and complex 2 by X-ray diffraction on single crystal. The crystal structure of complex 2 reveals a distorted tetrahedral geometry of Cu(II) in the first coordination sphere, which expands to a distorted octahedral environment by two symmetrically independent intramolecular metal⋯arene-π interactions. These interactions are provided by ortho-phenyl rings of both triazene N-oxide ligands 1. The aim of this work was to contribute to the architecture of new Cu(II)⋯arenecomplexes based on the synthesis of appropriated ligand for intramolecular interactions

  1. Anion carrier formation by calix[4]arene-bis-hydroxymethylphosphonic acid in bilayer membranes.

    PubMed

    Shatursky, Oleg Ya; Kasatkina, Ludmila A; Rodik, Roman V; Cherenok, Sergiy O; Shkrabak, Alexander A; Veklich, Tatiana O; Borisova, Tatiana A; Kosterin, Sergyi O; Kalchenko, Vitaly I

    2014-12-28

    The action of calix[4]arenes C-91, C-97, C-99, C-107 and C-160 on solvent-containing planar bilayer membranes made of cholesterol and egg phosphatidylcholine (egg PC) or synthetic 18-carbon-tail phospholipid DOPC has been investigated in a voltage-clamp mode. Within the range of calix[4]arenes tested, a steady-state voltage-dependent transmembrane current was achieved only after addition of calix[4]-arene C-99 (calix[4]arene-bis-hydroxymethylphosphonic acid) from the side of the membrane the positive potential was applied to. This current exhibited anion selectivity passing more chloride at negative potentials applied from the side of the membrane to which calix[4]arene C-99 was introduced. The kinetics and temperature-dependence determined for calix[4]arene C-99-mediated ionic transport suggest a carrier mode of facilitated diffusion.

  2. The volatile content of magmas from Arenal volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Wade, Jennifer A.; Plank, Terry; Melson, William G.; Soto, Gerardo J.; Hauri, Erik H.

    2006-09-01

    We provide the first direct measurements of water in mafic melts from Arenal volcano, Costa Rica. Ion microprobe analyses of olivine-hosted melt inclusions (MI) from the prehistoric ET3 (AR-19) and ET6 (AR-16) tephra layers reveal high concentrations of volatile species: ˜ 1-4 wt.% H 2O, 50-300 ppm CO 2, and > 3000 ppm S and Cl. The MI with the highest water concentrations are the most mafic, and the dataset as a whole records a history of degassing coupled with fractionation and ascent from ˜ 2 kbar to 0.2 kbar. Arenal MI form two groups based on their Al, CO 2 and S contents. The ET3 high-Al MI were trapped at the highest pressure, are closest to equilibrium with their host olivines (˜ Fo 79), which are closest to equilibrium with the bulk-rock liquid. These MI are excellent candidates for Arenal parental liquids, and can generate most Arenal volcanic rock compositions by crystal accumulation (up to 30%), or crystal fractionation at a range of pressure (0.5-3 kb) and H 2O contents (0.5-3.5 wt.%). The new sulfur data reported here predict total sulfur output over the past ˜ 30 years from bulk basaltic andesite liquid that matches well spectroscopic estimates, and resolves the previously noted imbalance. MI from different ET3 and ET6 samples show different F/Cl, while most trace element ratios show a limited range similar to that of the host rocks. The high water content (4 wt.% H 2O) of Arenal basaltic magma is somewhat surprising given the weak subduction signal recorded geochemically (e.g., low 10Be and B). The Arenal MI data contribute to a positive correlation between primary water contents and Ba/La in Central American volcanoes, although further testing is required given the small number of data points, and the expectation that water and trace elements should have different sources in the subduction zone.

  3. Synthesis and Structure of Corona[6](het)arenes Containing Mixed Bridge Units.

    PubMed

    Fu, Zhan-Da; Guo, Qing-Hui; Zhao, Liang; Wang, De-Xian; Wang, Mei-Xiang

    2016-06-01

    A one-pot nucleophilic aromatic substitution reaction of 3,6-dichlorotetrazine with various diphenols and dibenzenethiols produced corona[4]arene[2]tetrazines that contain mixed oxygen, sulfide, methylene, and sulfone linkages. Macrocyclic ring transformations employing an inverse-electron-demand Diels-Alder reaction of tetrazine moieties with enamines and the subsequent sulfide oxidation reaction afforded diverse corona[4]arene[2]pyridazines. The acquired corona[6]arenes adopted three types of conformational structures in the crystalline state. PMID:27182609

  4. Nitrosyl induces phosphorous-acid dissociation in ruthenium(II).

    PubMed

    Truzzi, Daniela Ramos; Ferreira, Antonio Gilberto; da Silva, Sebastião Claudino; Castellano, Eduardo Ernesto; Lima, Francisco das Chagas Alves; Franco, Douglas Wagner

    2011-12-28

    The trans-[Ru(NO)(NH(3))(4)(P(OH)(3))]Cl(3) complex was synthesized by reacting [Ru(H(2)O)(NH(3))(5)](2+) with H(3)PO(3) and characterized by spectroscopic ((31)P-NMR, δ = 68 ppm) and spectrophotometric techniques (λ = 525 nm, ε = 20 L mol(-1) cm(-1); λ = 319 nm, ε = 773 L mol(-1) cm(-1); λ = 241 nm, ε = 1385 L mol(-1) cm(-1); ν(NO(+)) = 1879 cm(-1)). A pK(a) of 0.74 was determined from infrared measurements as a function of pH for the reaction: trans-[Ru(NO)(NH(3))(4)(P(OH)(3))](3+) + H(2)O ⇌ trans-[Ru(NO)(NH(3))(4)(P(O(-))(OH)(2))](2+) + H(3)O(+). According to (31)P-NMR, IR, UV-vis, cyclic voltammetry and ab initio calculation data, upon deprotonation, trans-[Ru(NO)(NH(3))(4)(P(OH)(3))](3+) yields the O-bonded linkage isomer trans- [Ru(NO)(NH(3))(4)(OP(OH)(2))](2+), then the trans-[Ru(NO)(NH(3))(4)(OP(H)(OH)(2))](3+) decays to give the final products H(3)PO(3) and trans-[Ru(NO)(NH(3))(4)(H(2)O)](3+). The dissociation of phosphorous acid from the [Ru(NO)(NH(3))(4)](3+) moiety is pH dependent (k(obs) = 2.1 × 10(-4) s(-1) at pH 3.0, 25 °C). PMID:22027926

  5. Perforated monolayers: Design and synthesis of porous and cohesive monolayers from mercurated calix(n)arenes

    SciTech Connect

    Markowitz, M.A.; Janout, V.; Regen, S.L. ); Castner, D.G. )

    1989-10-11

    Mercuration of a series of O-alkylated calix(n)arenes (produced via reaction of tetrahydroxycalix(4)arene, pentahydroxylcalix(5)arene, hexahydroxycalix(6)arene, and heptahydroxycalix(7)arene with n-bromobutane and with n-bromohexadecane) afford an homologous series of calixarene-based surfactants that form stable monolayers at the air-water interface. Surface pressure-area isotherms, measured for each calixarene, yield limiting areas that are in excellent agreement with values predicted from space-filling models, if it is assumed that the base of each calixarene is parallel and the alkyl chains are perpendicular to the water surface. Introduction of malonic acid to the aqueous subphase results in a substantial increase in the cohesiveness of films derived from calix(4)arene-, calix(5)arene-, and calix(6)arene-based surfactants, as judged by changes in surface viscosity. X-ray photoelectron spectroscopic analysis of a Langmuir-Blodgett film, produced from a malonic acid stabilized calix(6)arene monolayer, shows a carboxylate/mercury ratio of 0.9.

  6. [Accumulation of polycyclic arenes in Baltic Sea algae].

    PubMed

    Veldre, I A; Itra, A R; Paal'me, L P; Kukk, Kh A

    1985-01-01

    The paper presents data on the level of benzo(a)pyrene (BP) and some other polycyclic arenes in alga and phanerogam specimens from different gulfs of the Baltic Sea. Algae were shown to absorb BP from sea water. The mean concentration of BP in sea water was under 0.004 microgram/1, while in algae it ranged 0.1-21.2 micrograms/kg dry weight. Algae accumulate BP to a higher degree than phanerogams. The highest concentrations of BP were found in algae Enteromorpha while the lowest ones in Furcellaria. In annual green algae, BP level was higher in autumn, i. e. at the end of vegetation period, than in spring. Brown algae Fucus vesiculosus is recommended for monitoring polycyclic arene pollution in the area from Vormsi Island to Käsmu and green algae Cladophora or Enteromorpha in the eastern part of the Finnish Gulf.

  7. [Accumulation of polycyclic arenes in Baltic Sea algae].

    PubMed

    Veldre, I A; Itra, A R; Paal'me, L P; Kukk, Kh A

    1985-01-01

    The paper presents data on the level of benzo(a)pyrene (BP) and some other polycyclic arenes in alga and phanerogam specimens from different gulfs of the Baltic Sea. Algae were shown to absorb BP from sea water. The mean concentration of BP in sea water was under 0.004 microgram/1, while in algae it ranged 0.1-21.2 micrograms/kg dry weight. Algae accumulate BP to a higher degree than phanerogams. The highest concentrations of BP were found in algae Enteromorpha while the lowest ones in Furcellaria. In annual green algae, BP level was higher in autumn, i. e. at the end of vegetation period, than in spring. Brown algae Fucus vesiculosus is recommended for monitoring polycyclic arene pollution in the area from Vormsi Island to Käsmu and green algae Cladophora or Enteromorpha in the eastern part of the Finnish Gulf. PMID:4060672

  8. Electronic properties of metal-arene functionalized graphene

    NASA Astrophysics Data System (ADS)

    Plachinda, Paul; Evans, David R.; Solanki, Raj

    2011-07-01

    We have employed first-principles density-functional calculations to study the electronic characteristics of covalently functionalized graphene by metal-bis-arene chemistry. It is shown that functionalization with M-bis-arene (M = Ti, V, Cr, Mn, Fe) molecules leads to an opening in the bandgap of graphene (up to 0.81 eV for the Cr derivative), and as a result, transforms it from a semimetal to a semiconductor. The bandgap induced by attachment of a metal atom topped by a benzene ring is attributed to modification of π-conjugation and depends on the concentration of functionalizing molecules. This approach offers a means of tailoring the band structure of graphene and potentially its applications for future electronic devices.

  9. Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu(2.).

    PubMed

    Hosseinzadeh, Rahman; Nemati, Mohammad; Zadmard, Reza; Mohadjerani, Maryam

    2016-01-01

    Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu(2+). The receptor molecule L exhibited a pronounced selectivity towards Cu(2+) over other mono and divalent ions. The formation of the complex between L and Cu(2+) was evaluated by absorption, fluorescence and (1)H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu(2+). The 1:1 stoichiometry of the obtained complex has been determined by Job's plot. The association constant determined by fluorescence titration was found to be 1.8 × 10(6) M(-1). The sensor showed a linear response toward Cu(2+) in the concentration range from 1 to 10 µM with a detection limit of 9.6 × 10(-8) M. PMID:27559419

  10. Comparative study of tributyltin adsorption onto mesoporous silica functionalized with calix[4]arene, p-tert-butylcalix[4]arene and p-sulfonatocalix[4]arene.

    PubMed

    Alahmadi, Sana; Mohamad, Sharifah; Maah, Mohd Jamil

    2014-01-01

    The adsorption of tributyltin (TBT), onto three mesoporous silica adsorbents functionalized with calix[4]arene, p-tert-butylcalix[4]arene and p-sulfonatocalix[4]arene (MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S, respectively) has been compared. Batch adsorption experiments were carried out and the effect of contact time, initial TBT concentration, pH and temperature were studied. The Koble-Corrigan isotherm was the most suitable for data fitting. Based on a Langmuir isotherm model, the maximum adsorption capacities were 12.1212, 16.4204 and 7.5757 mg/g for MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S, respectively. The larger uptake and stronger affinity of MCM-TDI-PC4 than MCM-TDI-C4 and MCM-TDI-C4S probably results from van der Waals interactions and the pore size distribution of MCM-TDI-PC4. Gibbs free energies for the three adsorption processes of TBT presented a negative value, reflecting that TBT/surface interactions are thermodynamic favorable and spontaneous. The interaction processes were accompanied by an increase of entropy value for MCM-TDI-C4 and MCM-TDI-C4S (43.7192 and 120.7609 J/mol K, respectively) and a decrease for MCM-TDI-PC4 (-37.4704 J/mol K). It is obviously observed that MCM-TDI-PC4 spontaneously adsorbs TBT driven mainly by enthalpy change, while MCM-TDI-C4 and MCM-TDI-C4S do so driven mainly by entropy changes. PMID:24727422

  11. Comparative study of tributyltin adsorption onto mesoporous silica functionalized with calix[4]arene, p-tert-butylcalix[4]arene and p-sulfonatocalix[4]arene.

    PubMed

    Alahmadi, Sana; Mohamad, Sharifah; Maah, Mohd Jamil

    2014-04-10

    The adsorption of tributyltin (TBT), onto three mesoporous silica adsorbents functionalized with calix[4]arene, p-tert-butylcalix[4]arene and p-sulfonatocalix[4]arene (MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S, respectively) has been compared. Batch adsorption experiments were carried out and the effect of contact time, initial TBT concentration, pH and temperature were studied. The Koble-Corrigan isotherm was the most suitable for data fitting. Based on a Langmuir isotherm model, the maximum adsorption capacities were 12.1212, 16.4204 and 7.5757 mg/g for MCM-TDI-C4, MCM-TDI-PC4 and MCM-TDI-C4S, respectively. The larger uptake and stronger affinity of MCM-TDI-PC4 than MCM-TDI-C4 and MCM-TDI-C4S probably results from van der Waals interactions and the pore size distribution of MCM-TDI-PC4. Gibbs free energies for the three adsorption processes of TBT presented a negative value, reflecting that TBT/surface interactions are thermodynamic favorable and spontaneous. The interaction processes were accompanied by an increase of entropy value for MCM-TDI-C4 and MCM-TDI-C4S (43.7192 and 120.7609 J/mol K, respectively) and a decrease for MCM-TDI-PC4 (-37.4704 J/mol K). It is obviously observed that MCM-TDI-PC4 spontaneously adsorbs TBT driven mainly by enthalpy change, while MCM-TDI-C4 and MCM-TDI-C4S do so driven mainly by entropy changes.

  12. Theoretical investigation on the molecular inclusion process of prilocaine into p-sulfonic acid calix[6]arene

    NASA Astrophysics Data System (ADS)

    de Sousa, Sara M. R.; Fernandes, Sergio A.; De Almeida, Wagner B.; Guimarães, Luciana; Abranches, Paula A. S.; Varejão, Eduardo V. V.; Nascimento, Clebio S., Jr.

    2016-02-01

    The present letter reports, for the first time, results from a theoretical analysis of the inclusion process involving the prilocaine into the p-sulfonic acid calix[6]arene. Structure and stabilization energies were calculated, in both gas and aqueous phases, using a sequential methodology based on semiempirical and Density Functional Theory (DFT) calculations. From the results, a qualitative structure property relationship could be established with some main structural features being relevant for inclusion complex stabilization: (i) the hydrogen bonds established between guest and host molecules, (ii) the dispersion effect and (iii) the inclusion mode of guest molecule into the host cavity.

  13. Ion binding compounds, radionuclide complexes, methods of making radionuclide complexes, methods of extracting radionuclides, and methods of delivering radionuclides to target locations

    DOEpatents

    Chen, Xiaoyuan; Wai, Chien M.; Fisher, Darrell R.

    2000-01-01

    The invention pertains to compounds for binding lanthanide ions and actinide ions. The invention further pertains to compounds for binding radionuclides, and to methods of making radionuclide complexes. Also, the invention pertains to methods of extracting radionuclides. Additionally, the invention pertains to methods of delivering radionuclides to target locations. In one aspect, the invention includes a compound comprising: a) a calix[n]arene group, wherein n is an integer greater than 3, the calix[n]arene group comprising an upper rim and a lower rim; b) at least one ionizable group attached to the lower rim; and c) an ion selected from the group consisting of lanthanide and actinide elements bound to the ionizable group. In another aspect, the invention includes a method of extracting a radionuclide, comprising: a) providing a sample comprising a radionuclide; b) providing a calix[n]arene compound in contact with the sample, wherein n is an integer greater than 3; and c) extracting radionuclide from the sample into the calix[n]arene compound. In yet another aspect, the invention includes a method of delivering a radionuclide to a target location, comprising: a) providing a calix[n]arene compound, wherein n is an integer greater than 3, the calix[n]arene compound comprising at least one ionizable group; b) providing a radionuclide bound to the calix[n]arene compound; and c) providing an antibody attached to the calix[n]arene compound, the antibody being specific for a material found at the target location.

  14. Experimental and theoretical study of the influence of peripheral environment on magnetic properties of tetranuclear manganese skeleton in new representatives of calix[4]arene-containing [MnII2 MnIII2] clusters

    NASA Astrophysics Data System (ADS)

    Aldoshin, S. M.; Antipin, I. S.; Solov'eva, S. E.; Sanina, N. A.; Korchagin, D. V.; Shilov, G. V.; Mushenok, F. B.; Utenyshev, A. N.; Bozhenko, K. V.

    2015-02-01

    A new representative of calix[4]arene-containing tetranuclear manganese complexes of [Mn2IIIMn2II] type with 2,2‧-dipyridyl bidentate ligand coordinated in the equatorial plane of the complex (II) has been obtained. The complex is crystallized in monoclinic space group P21/c (a = 14.9402(7) Å, b = 32.816(1) Å, c = 21.595(1) Å, β = 106.888(4)). Its magnetic properties have been studied by the method of SQUID magnetometry. The substitution of a peripheral ligand was shown to influence substantially on the structure of the central fragment of the metal complex, and, hence, on the magnetic properties. Quantum-chemical calculations were performed for this complex and for the similar calix[4]arene-containing manganese complex with pyridine ligand (I). The influence of peripheral environment on the magnetic properties of tetranuclear manganese skeleton was elucidated for both complexes.

  15. The Geochemical and Petrological History of Arenal Volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Bolge, L. L.; Carr, M. J.; Feigenson, M. D.; Alvarado, G. E.

    2004-12-01

    The eruptive history of Arenal spans approximately 7,000 years, consisting of both explosive (tephra) eruptions and more effusive (lava) eruptions. Over the past 4,000 years Arenal has produced tephras layers roughly every 300 years, although there are two 500-600 year gaps in volcanic activity between 3000 and 1800 years ago. This study collected samples from 20 tephra and 10 lava units from the past 4,000 years and one lava and tephra unit dated at 7,000 years. The purpose of this study is to examine the geochemical evolution of the magma erupting at Arenal. Tephras from Arenal divide into two groups on the basis of SiO2 content. Mafic tephras have up to 53 wt.% SiO2, whereas felsic tephras have at least 56 wt.% SiO2. The gap in the SiO2 contents of the tephras is filled by lavas, which have SiO2 contents of 53-56 wt.%. The tephras that erupted prior to a hiatus at 3000 years ago consist mostly of mafic tephras. After the gap, tephras alternate between mafic and felsic. At approximately the time of this gap, the degree of melting, estimated from Zr/Hf and Nb/Ta, and the slab signal, estimated from Ba/La and Pb/Ce, also changed at Arenal. Prior to the gap the degree of melting is increasing along with the slab signal, both then begin decreasing after the gap. Over the past 4,000 years the mafic explosive tephras, which all have similar SiO2 contents, show an increase in compatible elements and a decrease in incompatible elements. This can also been seen in the felsic tephras, though not as well, since these tephras are not present throughout the whole eruptive history. This change in compatible and incompatible elements over time demonstrates fractionation occurring in the magma chamber prior to the entire eruptive sequence. The lavas, however, do not show this change in compatible and incompatible elements with time.

  16. Arylative Desulfonation of Diarylmethyl Phenyl Sulfone with Arenes Catalyzed by Scandium Triflate.

    PubMed

    Nambo, Masakazu; Ariki, Zachary T; Canseco-Gonzalez, Daniel; Beattie, D Dawson; Crudden, Cathleen M

    2016-05-20

    A scandium-triflate-catalyzed arylative desulfonation of diarylmethyl phenyl sulfones with arenes and heteroarenes was established. A variety of both sulfone and arene substrates were reacted to afford symmetric and nonsymmetric triarylmethanes in good yields. Further transformations of the resulting triarylmethanes and application to the concise synthesis of a bactericidal agent analogue were also demonstrated.

  17. Arylative Desulfonation of Diarylmethyl Phenyl Sulfone with Arenes Catalyzed by Scandium Triflate.

    PubMed

    Nambo, Masakazu; Ariki, Zachary T; Canseco-Gonzalez, Daniel; Beattie, D Dawson; Crudden, Cathleen M

    2016-05-20

    A scandium-triflate-catalyzed arylative desulfonation of diarylmethyl phenyl sulfones with arenes and heteroarenes was established. A variety of both sulfone and arene substrates were reacted to afford symmetric and nonsymmetric triarylmethanes in good yields. Further transformations of the resulting triarylmethanes and application to the concise synthesis of a bactericidal agent analogue were also demonstrated. PMID:27124389

  18. Calix[4]arene sulfonate as a template for forming fluorescent thiazole orange H-aggregates.

    PubMed

    Lau, Vivian; Heyne, Belinda

    2010-05-28

    The unexpected interaction between thiazole orange (TO) and calix[4]arene sulfonate is reported herein. H-Aggregates of TO switching on their fluorescence in solution are observed. Surprisingly, fluorescence enhancement is not linked to host-guest inclusion, but rather to calix[4]arene sulfonate serving as a template for several TO molecules.

  19. Catalytic arene hydrogenation using early transition metal hydride compounds. Progress report

    SciTech Connect

    Rothwell, I.P.

    1993-03-15

    Progress was achieved in four areas: development of surface supported Group 5 metal organometallic compounds for catalytic arene hydrogenation, isolation and reactivity of possible intermediates in catalytic arene hydrogenation, synthesis and characterization of new d{sup 0}-metal hydride compounds, and stoichiometric reactivity of d{sup 0} metal hydrido, aryloxide compounds. (DLC)

  20. Through-Space Effects of Substituents Dominate Molecular Electrostatic Potentials of Substituted Arenes

    PubMed Central

    Wheeler, Steven E.; Houk, K. N.

    2009-01-01

    Model systems have been studied using density functional theory to assess the contributions of π-resonance and through-space effects on electrostatic potentials of substituted arenes. The results contradict the widespread assumption that changes in molecular ESPs reflect only local changes in the electron density. Substituent effects on the ESP above the molecular plane are commonly attributed to changes in the aryl π-system. We show that ESP changes for a collection of substituted benzenes and more complex aromatic systems can be accounted for mostly by through-space effects, with no change in the aryl π-electron density. Only when π-resonance effects are substantial do they influence changes in the ESP above the aromatic ring to any extent. Examples of substituted arenes studied here are taken from the fields of drug design, host-guest chemistry, and crystal engineering. These findings emphasize the potential pitfalls of assuming ESP changes reflect changes in the local electron density. Since ESP changes are frequently used to rationalize and predict intermolecular interactions, these findings have profound implications for our understanding of substituent effects in countless areas of chemistry and molecular biology. Specifically, in many non-covalent interactions there are significant, often neglected, through-space interactions with the substituents. Finally, the present results explain the perhaps unexpectedly good performance of many molecular mechanics force-fields applied to supramolecular assembly phenomena and π-π interactions in biological systems despite the neglect of the polarization of the aryl π-system by substituents. PMID:20161573

  1. Identification of the structural determinants for anticancer activity of a ruthenium arene peptide conjugate.

    PubMed

    Meier, Samuel M; Novak, Maria; Kandioller, Wolfgang; Jakupec, Michael A; Arion, Vladimir B; Metzler-Nolte, Nils; Keppler, Bernhard K; Hartinger, Christian G

    2013-07-01

    Organometallic Ru(arene)-peptide bioconjugates with potent in vitro anticancer activity are rare. We have prepared a conjugate of a Ru(arene) complex with the neuropeptide [Leu(5)]-enkephalin. [Chlorido(η(6)-p-cymene)(5-oxo-κO-2-{(4-[(N-tyrosinyl-glycinyl-glycinyl-phenylalanyl-leucinyl-NH2)propanamido]-1H-1,2,3-triazol-1-yl)methyl}-4H-pyronato-κO)ruthenium(II)] (8) shows antiproliferative activity in human ovarian carcinoma cells with an IC50 value as low as 13 μM, whereas the peptide or the Ru moiety alone are hardly cytotoxic. The conjugation strategy for linking the Ru(cym) (cym=η(6)-p-cymene) moiety to the peptide involved N-terminal modification of an alkyne-[Leu(5)]-enkephalin with a 2-(azidomethyl)-5-hydroxy-4H-pyran-4-one linker, using Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC), and subsequent metallation with the Ru(cym) moiety. The ruthenium-bioconjugate was characterized by high resolution top-down electrospray ionization mass spectrometry (ESI-MS) with regard to peptide sequence, linker modification and metallation site. Notably, complete sequence coverage was obtained and the Ru(cym) moiety was confirmed to be coordinated to the pyronato linker. The ruthenium-bioconjugate was analyzed with respect to cytotoxicity-determining constituents, and through the bioconjugate models [{2-(azidomethyl)-5-oxo-κO-4H-pyronato-κO}chloride (η(6)-p-cymene)ruthenium(II)] (5) and [chlorido(η(6)-p-cymene){5-oxo-κO-2-([(4-(phenoxymethyl)-1H-1,2,3-triazol-1-yl]methyl)-4H-pyronato-κO}ruthenium(II)] (6) the Ru(cym) fragment with a triazole-carrying pyronato ligand was identified as the minimal unit required to achieve in vitro anticancer activity.

  2. Closed- to open-system differentiation at Arenal volcano (1968 2003)

    NASA Astrophysics Data System (ADS)

    Ryder, C. H.; Gill, J. B.; Tepley, F.; Ramos, F.; Reagan, M.

    2006-09-01

    Arenal volcano, located in northern Costa Rica, has been continuously erupting since 1968. Magmas during the first half of the eruption by volume (Stage 1: 1968-1971) were related by largely closed-system crystal fractionation that had produced a compositionally zoned magma chamber prior to 1968. It erupted downward from the most differentiated magma in 1968 to the most mafic by early 1971. In contrast, the second half of the eruption has been dominated by recharge and compositions have become more evolved with time (Stage 2: 1971-current). We base these conclusions on new major and trace element plus Sr-Nd-Hf-Pb isotope analyses of 56 whole rocks from throughout the eruption. Differentiates are enriched in incompatible elements in both stages, but compatible element concentrations drop much more during Stage 1 than 2. Changes during Stage 1 were successfully modeled using least squares and MELTS models despite the mineral complexity of the rocks. About 19% fractional crystallization of phenocryst phases (plagioclase > orthopyroxene > clinopyroxene > magnetite) is required, consistent with crystallization at 4 kb and from 1145 to 1088 °C of a melt initially containing 2.5 wt.% H 2O at quite oxidizing conditions (QFM + 2). An implication is that most phenocrysts formed during decompression and degassing. Changes during the second stage were successfully modeled using EC-E'RAχFC with the ratio of recharge to crystallization decreasing from 17 to 5 over ˜ 30 years. Crystallization rates (d FS / d t) increase from 0.05 to 0.4%/a from closed- to open-system behavior and are even faster than inferred from U-series disequilibria. The recharging magma results from a smaller degree of flux melting of a mostly similar source than for the resident magma prior to the eruption, with the two events separated by ˜ 450 years. The most recent compositions have no precedent at Arenal.

  3. Glued Langmuir-Blodgett bilayers from calix[n]arenes: Influence of calix[n]arene size on ionic cross-linking, film thickness, and permeation selectivity

    DOE PAGESBeta

    Wang, Minghui; Janout, Vaclav; Regen, Steven L.

    2010-07-12

    A homologous series of calix[4]arene-, calix[5]arene- and calix[6]arene-based surfactants, containing pendant trimethylammonium and n-hexadecyl groups, have been compared with respect to their ability (i) to undergo ionic crosslinking at the air/water interface, (ii) to incorporate poly(4-styrenesulfonate) (PSS) in Langmuir-Blodgett (LB) bilayers, and (iii) to act as barriers towards He, N2 and CO2 when assembled into crosslinked LB bilayers. As these calix[n]arenes increase in size, their ability to undergo ionic crosslinking has been found to increase, the thickness of corresponding glued LB bilayers has been found to decrease, and their barrier properties and permeation selectivities have been found to increase. Inmore » conclusion, the likely origin for these effects and the probable mechanism by which He, N2 and CO2 cross these ultrathin films are discussed.« less

  4. Lanthanide structures, coordination, and extraction investigations of a 1,3-bis(diethyl amide)-substituted caliz[4]arene ligand

    SciTech Connect

    Beer, P.D.; Ogden, M.I.; Drew, M.G.B.

    1996-04-10

    The synthesis and structure determinations of lanthanum, samarium, ytterbium, and lutetium complexes of 5,11,17,23-tetra-tert-butyl-25,27-bis((diethylcarbamoyl)methoxy)-26,28-dihydroxycalix[4]arene (L) are described. The four structures display similar characteristics with the trivalent lanthanide cation being encapsulated in an eight-coordinate oxygen environment, consisting of six oxygens from the calixarene, a water molecule, and unidentate picrate for lanthanum [La(L-2H)(picrate)(H{sub 2}O)]; and bidentate chelating picrate for the other lanthanides [Ln(L-2H)(picrate)]Ln = Sm, Yb, Lu. Under optimised experimental conditions solvent extraction investigations showed the calix[4]arene ligand L exhibited generally very high percentage extractabilities of lanthanide cations into dichloromethane, presumably on account of the ligand`s unique lower rim oxygen containing coordination sphere and its lipophilic exterior.

  5. Design of ratiometric fluorescent probes based on arene-metal-ion interactions and their application to Cd(II) and hydrogen sulfide imaging in living cells.

    PubMed

    Takashima, Ippei; Kinoshita, Miyuki; Kawagoe, Ryosuke; Nakagawa, Saika; Sugimoto, Manabu; Hamachi, Itaru; Ojida, Akio

    2014-02-17

    Non-coordinative interactions between a metal ion and the aromatic ring of a fluorophore can act as a versatile sensing mechanism for the detection of metal ions with a large emission change of fluorophores. We report the design of fluorescent probes based on arene-metal-ion interactions and their biological applications. This study found that various probes having different fluorophores and metal binding units displayed significant emission redshift upon complexation with metal ions, such as Ag(I), Cd(II), Hg(II), and Pb(II). X-ray crystallography of the complexes confirmed that the metal ions were held in close proximity to the fluorophore to form an arene-metal-ion interaction. Electronic structure calculations based on TDDFT offered a theoretical basis for the sensing mechanism, thus showing that metal ions electrostatically modulate the energy levels of the molecular orbitals of the fluorophore. A fluorescent probe was successfully applied to the ratiometric detection of the uptake of Cd(II) ions and hydrogen sulfide (H2S) in living cells. These results highlight the utility of interactions between arene groups and metal ions in biological analyses.

  6. An induced-fit process through mechanical pivoting of aromatic walls in host-guest chemistry of calix[6]arene aza-cryptands.

    PubMed

    Brugnara, Andrea; Fusaro, Luca; Luhmer, Michel; Prangé, Thierry; Colasson, Benoit; Reinaud, Olivia

    2014-05-01

    The per-ipso-nitration of a TMPA-capped calix[6]arene has been achieved. The substitution of the six bulky tBu substituents for nitro groups has a strong impact on the behavior of the ligand during guest recognition. The complexation of the aza cap (by H(+) or Cu(+)) associated with the encapsulation of a guest triggers an induced-fit process leading to the loss of the cone conformation of the host in favor of alternate conformations. Such a "pivoting" response of one or two walls of the calixarene core induces a large mechanical motion of the corresponding aromatic units. This stands in strong contrast with the "breathing" phenomena previously identified with other calix[6]arene-based complexes that expand or shrink the size of their cone as a function of the guest. Because of the covalently attached rigid TMPA cap, three arene units of this new calixarene host have a restricted mobility, which forces it to respond in a different manner to a supramolecular stress.

  7. [The Thiacalix [4] arene-Coumarin Fluorescence Probe Recognition for Fe³⁺ and Bovine Hemoglobin].

    PubMed

    Li, Yan-qin; Mu, Lan; Zeng, Xi; Li, Jun; Yamato, Takehiko

    2015-11-01

    1,3-alternate coumarin substituted thiacalix[4]arene fluorescent probe 1 was synthesised from 1,3-alternate diethyl thiacalix[4]arene and 7-hydroxycoumarin by-step reactions. In DMSO/H₂O (φ, 3/7, pH 7) solution, the strong fluorescence emission and UV absorption of probe 1 can be selectively quenched or significantly enhanced by Fe³⁺ ion. The probe 1 showed high Fe³⁺ selective fluorescence quenching or absorption enhancement over commonly coexistent metal ions in neutral aqueous media, and the limit of detections were obtained as low as 10⁻⁸ mol · L⁻¹ of Fe³⁺ by fluorescence and absorption spectrometry. Spectral titration, isothermal titration calorimetry and mass spectrometry were showed that probe and Fe³⁺ form 1:1 complexes, the constant up to 10⁵ L · mol⁻¹ and coordinate process was spontaneous by the mole binding free energy and entropy of probe with Fe³⁺. In addition, the probe can identification bovine hemoglobin (BHb) over other proteins through quenched its fluorescence in DMSO/H₂O (φ, 1/9, Tris-HCl, pH 7, 0.1 mol · L⁻¹ NaCl) media. The limit of detection was obtained as 0. 12 µg · mL⁻¹ of BHb, as well as a linearity of 0.2-3.0 µg · mL⁻¹, indicating the probe of high sensitivity and quantitation range. It can be used as a selective recognition Fe³⁺ and BHb of thiacalix[4] arene fluorescent probe.

  8. Clickable di- and tetrafunctionalized pillar[n]arenes (n = 5, 6) by oxidation-reduction of pillar[n]arene units.

    PubMed

    Ogoshi, Tomoki; Yamafuji, Daiki; Kotera, Daisuke; Aoki, Takamichi; Fujinami, Shuhei; Yamagishi, Tada-aki

    2012-12-21

    We report a new route for the selective synthesis of di- and tetrafunctionalized pillararenes via oxidation and reduction of the pillararene units. Hypervalent-iodine oxidation of perethylated pillar[5]arene afforded pillar[5]arene derivatives containing one benzoquinone unit and two benzoquinones at the A,B- and A,C-units. A pillar[6]arene derivative containing one benzoquinone unit was also synthesized. Reduction of the benzoquinone units yielded position-selective di- and tetrahydroxylated pillararene derivatives. This methodology avoids the generation of many constitutional isomers and overcomes the isolation problem of numerous constitutional isomers. From these hydroxylated pillararenes, Huisgen reaction-based clickable di- and tetraalkynylated pillar[5]arenes were prepared. Because of the highly selective and reactive nature of Huisgen alkyne-azide cycloaddition, these pillar[5]arenes can serve as key compounds for a large library of di- and tetrafunctionalized pillararenes. Based on these di- and tetrafunctionalized pillar[5]arenes as key compounds, fluorescent sensors were created by the modification of di- and tetrapyrene moieties via Huisgen-type click reactions.

  9. A dynamic [1]catenane with pH-responsiveness formed via threading-followed-by-complexation.

    PubMed

    Yan, Xuzhou; Wei, Peifa; Li, Zhengtao; Zheng, Bo; Dong, Shengyi; Huang, Feihe; Zhou, Qizhong

    2013-03-28

    Driven by orthogonal pillar[5]arene-based and crown ether-based molecular recognitions, a dynamic [1]catenane with pH-responsiveness was constructed via threading-followed-by-complexation. PMID:23423220

  10. Hybrid liposomal PEGylated calix[4]arene systems as drug delivery platforms for curcumin.

    PubMed

    Drakalska, Elena; Momekova, Denitsa; Manolova, Yana; Budurova, Dessislava; Momekov, Georgi; Genova, Margarita; Antonov, Liudmil; Lambov, Nikolay; Rangelov, Stanislav

    2014-09-10

    The tremendous therapeutic potential of curcumin as a chemopreventive, antineoplastic and chemosensitizing agent has failed to progress towards clinical development and commercialization due to its unfavorable physicochemical properties, low aqueous solubility, chemical instability, and pharmacokinetics. The present contribution is focused on the feasibility of using PEGylated calixarene, in particular polyoxyethylene-derivatized tert-butylcalix[4]arene, to prepare various platforms for delivery of curcumin such as inclusion complex, supramolecular aggregates, and hybrid liposomal systems. The inclusion complex is characterized by UV-vis and FT-IR spectroscopy as well as thermal gravimetrical analysis and differential scanning calorimetry. At concentrations exceeding the critical micellization concentration of PEGylated calixarene, the tremendous solubility enhancement of curcumin is attributed to additional solubilization and hydrophobic non-covalent interactions of the drug with supramolecular aggregates. A hybrid liposomal system is created via encapsulation of the inclusion complex in dipalmitoylphosphatidylcholine:cholesterol liposomes. Bare and liposomal curcumin:BEC-X inclusion complexes, as well as free curcumin were additionally investigated for cytotoxicity and apoptogenic activity against human tumor cell lines.

  11. A fluorescent and phosphorescent nanoporous solid: crystalline calix[4]arene.

    PubMed

    Oueslati, Issam; Coleman, Anthony W; de Castro, Baltazar; Berberan-Santos, Mário N

    2008-11-01

    Calix[4]arene forms elongated nanoporous microcrystals. The pores are linear nano-channels (1.7 nm diameter) arranged in a honeycomb network. The crystals luminesce at room temperature according to a variety of processes that include monomer fluorescence (lifetime of ca. 1.1 ns), dimer fluorescence (lifetime of ca. 5.4 ns), and monomer phosphorescence (lifetime of ca. 2 s). The dimers result from pi-orbital overlap of adjacent phenol groups from neighboring nano-channels, with C-C distances of ca. 4 A.

  12. Plagioclase and pyroxene hosted melt inclusions in basaltic andesites of the current eruption of Arenal volcano, Costa Rica

    NASA Astrophysics Data System (ADS)

    Streck, Martin J.; Wacaster, Sue

    2006-09-01

    In this study, we investigated melt inclusions hosted in pyroxene and plagioclase to find direct evidence for the composition of melt components in the pre-eruptive magmas of the current eruption of Arenal volcano and to further shed light on the petrogenetic history of remarkably uniform basaltic andesitic bulk compositions. Composition of melt inclusions ranges widely regardless of whether an inclusion is hosted by plagioclase or by pyroxene and whether crystals with inclusions came from tephra samples or from slower emplaced lava flows. However, inclusions from each type of host mineral have distinct evolutionary trends most consistent with being mainly introduced by post-emplacement crystallization of the enclosing host, which is also supported by the composition of groundmass glasses. At the least-modified compositions, plagioclase and pyroxene inclusion trends overlap allowing for identification of melt compositions entrapped by both phases and, thus, strongly suggesting that these melt compositions existed in the reservoir prior to entrapment. Most of these are "dacitic" (61 to 64 wt.% SiO 2) and strongly match phenocryst-poor dacitic magmas of earlier eruptive phases of Arenal [Borgia, A., Poore, C., Carr, M.J., Melson, W.G., Alvarado, G.E., 1988. Structural, stratigraphic, and petrologic aspects of the Arenal-Chato volcanic system, Costa Rica: evolution of a young stratovolcanic complex. Bull Volcanol, 50, 86-105], suggesting earlier dacitic magmas may have been generated by melt-extraction processes. Correction for host crystallization of some inclusions also suggests that melt components as mafic as ˜ 53 wt.% may have been entrapped. All melt components inferred to have existed in the magmatic reservoirs prior to entrapment have low Mg# (38-45) yielding evidence for liquid compositions required for crystallizing the bulk of observed pyroxene and likely also olivine. Water rich (> 5 wt.%, by difference) and probably undegassed (S = 400-1600 ppm, Cl =

  13. The synthesis and characterization of azocalix[4]arene based chemosensors and investigation of their properties

    NASA Astrophysics Data System (ADS)

    Elçin, Serkan; Çılgı, Gülbanu Koyundereli; Bayrakdar, Alpaslan; Deligöz, Hasalettin

    2015-05-01

    In the present study, azocalix[4]arenes were prepared by linking 4-methoxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo and 4-nitroaniline to calix[4]arene through a diazo-coupling reaction. A new family of azocalix[4]arene tetraester derivatives, (4a-f), have been prepared with the incorporation of ethyl ester units to azocalix[4]arene. Characterization of the synthesized azocalix[4]arenes was carried using elemental analyses, UV-vis, FT-IR and 1H NMR spectroscopic techniques. The effect of varying pH levels and solvent types on the absorption ability of azocalix[n]arenes substituted with electron-donating and electron-withdrawing groups was examined. Thermal decomposition of azocalix[4]arene derivatives (4a-f) was investigated by means of thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) analyses. In conclusion of the examination of the extraction we found a selectivity characteristic of these compounds toward Ag+, Hg+ and Hg2+ cations.

  14. The synthesis and characterization of azocalix[4]arene based chemosensors and investigation of their properties.

    PubMed

    Elçin, Serkan; Çılgı, Gülbanu Koyundereli; Bayrakdar, Alpaslan; Deligöz, Hasalettin

    2015-05-01

    In the present study, azocalix[4]arenes were prepared by linking 4-methoxy, 4-methyl, 4-ethyl, 4-chloro, 4-bromo and 4-nitroaniline to calix[4]arene through a diazo-coupling reaction. A new family of azocalix[4]arene tetraester derivatives, (4a-f), have been prepared with the incorporation of ethyl ester units to azocalix[4]arene. Characterization of the synthesized azocalix[4]arenes was carried using elemental analyses, UV-vis, FT-IR and (1)H NMR spectroscopic techniques. The effect of varying pH levels and solvent types on the absorption ability of azocalix[n]arenes substituted with electron-donating and electron-withdrawing groups was examined. Thermal decomposition of azocalix[4]arene derivatives (4a-f) was investigated by means of thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) analyses. In conclusion of the examination of the extraction we found a selectivity characteristic of these compounds toward Ag(+), Hg(+) and Hg(2+) cations.

  15. Thalidomide teratogenesis: evidence for a toxic arene oxide metabolite.

    PubMed

    Gordon, G B; Spielberg, S P; Blake, D A; Balasubramanian, V

    1981-04-01

    It was postulated that thalidomide causes birth defects by being metabolized to a toxic electrophilic intermediate. This hypothesis was tested by using an in vitro assay in which drug toxicity to human lymphocytes was assessed in the presence of a hepatic microsomal drug metabolizing system. Maternal hepatic microsomes from pregnant rabbits mediated the production of a metabolite that was toxic to lymphocytes. Toxicity was enhanced by inhibitors of epoxide hydrolase (EC 3.3.2.3) and abolished by adding the purified enzyme to the incubation medium. The metabolite thus appears to be in arene oxide, consistent with the previously reported isolation of phenolic metabolites of thalidomide from the urine of treated animals. Two teratogenic analogs of thalidomide (phthalimidophthalimide and phthalimidinoglutarimide) were also toxic in the system; two nonteratogenic analogs (phthalimide and hexahydrothalidomide) were not toxic, even in the presence of epoxide hydrolase inhibitors. The toxic metabolite of thalidomide was not produced by rat liver microsomes (the rat is not sensitive to thalidomide teratogenesis) but was produced by hepatic preparations from maternal rabbits, and rabbit, monkey, and human (all sensitive species) fetuses. A toxic arene oxide therefore may be involved in the teratogenicity of thalidomide.

  16. Theoretical study on interactions of fluorinated organomercurials with arene and gold fragments.

    PubMed

    Mendizabal, Fernando; Miranda-Rojas, Sebastián; Barrientos, Lorena

    2015-10-21

    The electronic structure and spectroscopic properties of [Hg(C6F5)2]2-{L}, [Hg3(o-C6F4)3]2·{L} (L = naphthalene, biphenyl, fluorene) and [Hg3(o-C6F4)3]{Au3(μ-C(OEt)=NC6H4CH3)3}n (n = 1, 2) adducts were studied at the HF, MP2, SCS-MP2, DFT and DFT-D3 levels. The intermolecular interactions among the fragments were analyzed using the levels of calculations proposed. The energy decomposition analysis at the TPSS-D3 level was used to define the dominant components of the interaction. The van der Waals interactions between mercury and arene (Hg-arene) were found to be the main short-range stability contribution in the [Hg(C6F5)2]2-{L} and [Hg3(o-C6F4)3]2·{L} complexes. At the MP2, SCS-MP2 and DFT-D3 levels, equilibrium Hg-C distances are between 360 and 310 pm. The pair-wise energies were found to be between 18.0 and 6.0 kJ mol(-1). In the [Hg3(o-C6F4)3]{Au3(μ-C(OEt)=NC6H4CH3)3}n (n = 1, 2) complexes the metallophilic intermolecular interaction is Hg-Au. Pair-wise energies of 85.7, 39.4, 78.1 and 57.9 kJ mol(-1) were found at the MP2, SCS-MP2, TPSS-D3 and PBE-D3 levels using the [Hg3(o-C6F4)3]{Au3(μ-C(OEt)=NC6H4CH3)3} model. The same trend is maintained for the [Hg3(o-C6F4)3]{Au3(μ-C(OEt)=NC6H4CH3)3}2 model: 73.4, 29.3, 70.6 and 61.3 kJ mol(-1) by MP2, SCS-MP2, TPSS-D3 and PBE-D3, respectively. The absorption spectra of these complexes were calculated using the single excitation time-dependent method at the TPSS-D3 level to validate the models against the experimental data.

  17. Odd-numbered oxacalix[n]arenes (n = 5, 7): synthesis and solid-state structures.

    PubMed

    Van Rossom, Wim; Robeyns, Koen; Ovaere, Magriet; Van Meervelt, Luc; Dehaen, Wim; Maes, Wouter

    2011-01-01

    The critical synthetic access to odd-numbered calix[n]arenes has evidently resulted in less attention for these macrocycles, although specific molecular recognition phenomena have been observed for some of them. A straightforward fragment coupling approach has been designed, applying kinetically controlled nucleophilic aromatic substitution reaction conditions, affording odd-numbered oxacalix[n]arenes (n = 5, 7) selectively in high yields. The solid-state conformational behavior and the oxacalix[n]arene cavity size were explored by single-crystal X-ray diffraction studies.

  18. A neutral supramolecular hyperbranched polymer fabricated from an AB2 -type copillar[5]arene.

    PubMed

    Wang, Xiaoyang; Deng, Hongmei; Li, Jian; Zheng, Kai; Jia, Xueshun; Li, Chunju

    2013-12-01

    A heterotritopic copillar[5]arene monomer by introducing effective neutral guest moieties (methylene chains end-capped with cyano and triazole groups) to a pillar[5]arene macrocycle is prepared. This well-designed AB2 -type copillar[5]arene contains strong host-guest recognition motifs that are connected with relatively flexible and long linkers, thus efficiently assembles to form supramole-cular hyperbranched polymer (SHP) in chloroform solution, which is characterized by various techniques including (1) H NMR, DOSY, viscosity, DLS, and TEM. Particularly, this supramolecular polymer can be effectively depolymerized by adding a competitive butanedinitrile guest.

  19. Immobilization of [60]fullerene on silicon surfaces through a calix[8]arene layer

    NASA Astrophysics Data System (ADS)

    Busolo, Filippo; Silvestrini, Simone; Armelao, Lidia; Maggini, Michele

    2013-10-01

    In this work, we report the functionalization of flat Si(100) surfaces with a calix[8]arene derivative through a thermal hydrosilylation process, followed by docking with [60]fullerene. Chemical grafting of calix[8]arene on silicon substrates was evaluated by X-ray photoelectron spectroscopy, whereas host-guest immobilization of fullerene was demonstrated by atomic force microscopy and sessile drop water contact angle measurements. Surface topographical variations, modelled on the basis of calix[8]arene and [60]fullerene geometrical parameters, are consistent with the observed morphological features relative to surface functionalization and to non-covalent immobilization of [60]fullerene.

  20. Immobilization of [60]fullerene on silicon surfaces through a calix[8]arene layer

    SciTech Connect

    Busolo, Filippo; Silvestrini, Simone; Maggini, Michele; Armelao, Lidia

    2013-10-28

    In this work, we report the functionalization of flat Si(100) surfaces with a calix[8]arene derivative through a thermal hydrosilylation process, followed by docking with [60]fullerene. Chemical grafting of calix[8]arene on silicon substrates was evaluated by X-ray photoelectron spectroscopy, whereas host-guest immobilization of fullerene was demonstrated by atomic force microscopy and sessile drop water contact angle measurements. Surface topographical variations, modelled on the basis of calix[8]arene and [60]fullerene geometrical parameters, are consistent with the observed morphological features relative to surface functionalization and to non-covalent immobilization of [60]fullerene.

  1. [Mn(III)4Ln(III)4] calix[4]arene clusters as enhanced magnetic coolers and molecular magnets.

    PubMed

    Karotsis, Georgios; Kennedy, Stuart; Teat, Simon J; Beavers, Christine M; Fowler, Drew A; Morales, Juan J; Evangelisti, Marco; Dalgarno, Scott J; Brechin, Euan K

    2010-09-22

    The use of methylene-bridged calix[4]arenes in 3d/4f chemistry produces a family of clusters of general formula [Mn(III)(4)Ln(III)(4)(OH)(4)(C4)(4)(NO(3))(2)(DMF)(6)(H(2)O)(6)](OH)(2) (where C4 = calix[4]arene; Ln = Gd (1), Tb (2), Dy (3)). The molecular structure describes a square of Ln(III) ions housed within a square of Mn(III) ions. Magnetic studies reveal that 1 has a large number of molecular spin states that are populated even at the lowest investigated temperatures, while the ferromagnetic limit S = 22 is being approached only at the highest applied fields. This, combined with the high magnetic isotropy, makes the complex an excellent magnetic refrigerant for low-temperature applications. Replacement of the isotropic Gd(III) ions with the anisotropic Tb(III) and Dy(III) ions "switches" the magnetic properties of the cluster so that 2 and 3 behave as low-temperature molecular magnets, displaying slow relaxation of the magnetization.

  2. Supramolecular chemistry of p-sulfonatocalix[5] arene: A water-soluble, bowl-shaped host with a large molecular cavity

    SciTech Connect

    Steed, J.W.; Johnson, C.P.; Barnes, C.L.; Kuneja, R.K.; Atwood, J.L.; Reilly, S.; Hollis, R.L.; Smith, P.H.; Clark, D.L.

    1995-11-22

    The first X-ray crystallographic studies are reported for water-soluble inclusion complexes of the macrocyclic p-sulfonatocalix[5]arene (1b). The complexes Na{sub 7} [p-sulfonatocalix[5]arene].18H{sub 2}O (2) and Na{sub 5} [p-sulfonatocalix]5[arene].py-N-O.8.5H{sub 2}O (3) containing water and pyridine N-oxide (py-N-O) guest species have been isolated. In 2 the large bowl-shaped cavity of the host molecule is occupied by a total of three water molecules, while for 3 a single molecule of pyridine N-oxide is included and interacts with the host via a strong hydrogen bond to a protonated sulfonate substituent. The behavior of 1b as a ligand for a number of lanthanide elements is also reported. Low temperature X-ray structural studies reveal that coordination of the Ln{sup 3+} metal ions to the calixarene ligand occurs exclusively via the sulfonato functionalities and not the phenolic oxygen atoms as suggested by Shinkai et al. for the complexation of UO{sub 2}{sup 2+} by lb. In complex 2 the calixarene exists as the heptaanion. In contrast, crystallization from acidic solution results in complexes 3-8 retaining all their phenolic protons. The protonation constants of 1b have been measured in aqueous solution: pK{sub a} = 10.96(8), 7. 63(5), and 4.31(1) at 25{degree}C and 0.1 M KNO{sub 3}. 24 refs., 8 figs., 1 tab.

  3. Why do cationic hydridoiridium(III) complexes with beta-aminophosphane ligands favour the transfer hydrogenation of ketones over the direct "H2-hydrogenation"?--A computational approach.

    PubMed

    Puchta, Ralph; Dahlenburg, Lutz; Clark, Timothy

    2008-01-01

    Density functional theory and ab initio molecular orbital calculations show that the observed inability of cationic hydridoiridium(III) complexes with beta-aminophosphane ligands to catalyse the direct hydrogenation of carbonyl compounds with dihydrogen ("H2-hydrogenation") in contrast to their ruthenium(II) equivalents is due to the inability of H2 to displace a coordinated solvent molecule from an intermediate hydrido complex. PMID:18720495

  4. Calix[4]arene Based Highly Efficient Fluorescent Sensor for Au(3+) and I(.).

    PubMed

    Memon, Shahabuddin; Bhatti, Ashfaque Ali; Bhatti, Asif Ali; Ocak, Ümmühan; Ocak, Miraç

    2015-09-01

    This approach disclose the selective fluorogenic ion sensing ability of 5,11,17,23-tetratertbutyl-25,27-bis((2hydroxynaphthylimino)1,2-ethylenediaminecarbonylmethoxy)-26,28 dihydroxycalix[4]arene (C4NSB). Binding property of receptor probed by using selected various cations and anions with conferring of results that demonstrates 'turn-off' fluorescence response and significantly high chromogenic selectivity toward Au(3+) and I(-). Furthermore, selective nature of receptor was investigated in the presence of different co-existing competing ions. The limit of detection (LOD) for Au(3+) and I(-) was determined as 1.5 × 10(-5) and 4.5 × 10(-6) M respectively. Receptor C4NSB form (1:1) stoichiometric complex with both ions and their binding constants were calculated as 8.0 × 10(2) for Au(3+) and 15.6 × 10(2) M(-1) for I(-). Complexes were also characterized through FT-IR spectroscopy.

  5. Gas Concentration Mapping of Arenal Volcano Using AVEMS

    NASA Technical Reports Server (NTRS)

    Diaz, J. Andres; Arkin, C. Richard; Griffin, Timothy P.; Conejo, Elian; Heinrich, Kristel; Soto, Carlomagno

    2005-01-01

    The Airborne Volcanic Emissions Mass Spectrometer (AVEMS) System developed by NASA-Kennedy Space Center and deployed in collaboration with the National Center for Advanced Technology (CENAT) and the University of Costa Rica was used for mapping the volcanic plume of Arenal Volcano, the most active volcano in Costa Rica. The measurements were conducted as part of the second CARTA (Costa Rica Airborne Research and Technology Application) mission conducted in March 2005. The CARTA 2005 mission, involving multiple sensors and agencies, consisted of three different planes collecting data over all of Costa Rica. The WB-57F from NASA collected ground data with a digital camera, an analog photogrametric camera (RC-30), a multispectral scanner (MASTER) and a hyperspectral sensor (HYMAP). The second aircraft, a King Air 200 from DoE, mounted with a LIDAR based instrument, targeted topography mapping and forest density measurements. A smaller third aircraft, a Navajo from Costa Rica, integrated with the AVEMS instrument and designed for real-time measurements of air pollutants from both natural and anthropogenic sources, was flown over the volcanoes. The improved AVEMS system is designed for deployment via aircraft, car or hand-transport. The 85 pound system employs a 200 Da quadrupole mass analyzer, has a volume of 92,000 cubic cm, requires 350 W of power at steady state, can operate up to an altitude of 41,000 feet above sea level (-65 C; 50 torr). The system uses on-board gas bottles on-site calibration and is capable of monitoring and quantifying up to 16 gases simultaneously. The in-situ gas data in this work, consisting of helium, carbon dioxide, sulfur dioxide and acetone, was acquired in conjunction of GPS data which was plotted with the ground imagery, topography and remote sensing data collected by the other instruments, allowing the 3 dimensional visualization of the volcanic plume at Arenal Volcano. The modeling of possible scenarios of Arenal s activity and its

  6. Irritable Bowel Syndrome Treatments Aren't One-Size-Fits-All

    MedlinePlus

    ... Bowel Syndrome Treatments Aren't One-Size-Fits-All Share Tweet Linkedin Pin it More sharing options ... the United States. No one remedy works for all patients, so there’s a great medical need to ...

  7. Manganese-Mediated C-H Alkylation of Unbiased Arenes Using Alkylboronic Acids.

    PubMed

    Castro, Susana; Fernández, Juan J; Fañanás, Francisco J; Vicente, Rubén; Rodríguez, Félix

    2016-06-27

    The alkylation of arenes is an essential synthetic step of interest not only from the academic point of view but also in the bulk chemical industry. Despite its limitations, the Friedel-Crafts reaction is still the method of choice for most of the arene alkylation processes. Thus, the development of new strategies to synthesize alkyl arenes is a highly desirable goal, and herein, we present an alternative method to those conventional reactions. Particularly, a simple protocol for the direct C-H alkylation of unbiased arenes with alkylboronic acids in the presence of Mn(OAc)3 ⋅2H2 O is reported. Primary or secondary unactivated alkylboronic acids served as alkylating agents for the direct functionalization of representative polyaromatic hydrocarbons (PAHs) or benzene. The results are consistent with a free-radical mechanism. PMID:27124250

  8. Polycationic pillar[5]arene derivatives: interaction with DNA and biological applications.

    PubMed

    Nierengarten, Iwona; Nothisen, Marc; Sigwalt, David; Biellmann, Thomas; Holler, Michel; Remy, Jean-Serge; Nierengarten, Jean-François

    2013-12-16

    Dendritic pillar[5]arene derivatives have been efficiently prepared by grafting dendrons with peripheral Boc-protected amine subunits onto a preconstructed pillar[5]arene scaffold. Upon cleavage of the Boc-protected groups, water-soluble pillar[5]arene derivatives with 20 (13) and 40 (14) peripheral ammonium groups have been obtained. The capability of these compounds to form stable nanoparticles with plasmid DNA has been demonstrated by gel electrophoresis, transmission electron microscopy (TEM), and dynamic light scattering (DLS) investigations. Transfection efficiencies of the self-assembled 13/pCMV-Luc and 14/pCMV-Luc polyplexes have been evaluated in vitro with HeLa cells. The transfection efficiencies found for both compounds are good, and pillar[5]arenes 13 and 14 show very low toxicity if any.

  9. Aqueous chemistry and antiproliferative activity of a pyrone-based phosphoramidate Ru(arene) anticancer agent.

    PubMed

    Meier, Samuel M; Novak, Maria S; Kandioller, Wolfgang; Jakupec, Michael A; Roller, Alexander; Keppler, Bernhard K; Hartinger, Christian G

    2014-07-14

    A water-stable phosphoramidate Ru(arene) metallodrug shows antiproliferative activity comparable to KP1019 in human cancer cell lines. This novel compound can cross-link the peptide backbone of cytochrome c, but features low apoptosis inducing properties.

  10. Metal-free oxidative decarbonylative coupling of aromatic aldehydes with arenes: direct access to biaryls.

    PubMed

    Tang, Ren-Jin; He, Qing; Yang, Luo

    2015-04-01

    A metal-free oxidative decarbonylative coupling of aromatic aldehydes with electron-rich or electron-deficient arenes to produce biaryl compounds was developed. This novel coupling was proposed to proceed via a non-chain radical homolytic aromatic substitution (HAS) type mechanism, based on the substrate scope, ortho-regioselectivity, radical trapping experiments and DFT calculation studies. With the ready availability of aromatic aldehydes and arenes, metal-free conditions should make this coupling attractive for the biaryl synthesis.

  11. Double heteroatom functionalization of arenes using benzyne three-component coupling.

    PubMed

    García-López, José-Antonio; Çetin, Meliha; Greaney, Michael F

    2015-02-01

    Arynes participate in three-component coupling reactions with N, S, P, and Se functionalities to yield 1,2-heteroatom-difunctionalized arenes. Using 2-iodophenyl arylsulfonates as benzyne precursors, we could effectively add magnesiated S-, Se-, and N-nucleophilic components to the strained triple bond. In the same pot, addition of electrophilic N, S, or P reagents and a copper(I) catalyst trapped the intermediate aryl Grignard to produce a variety of 1,2-difunctionalized arenes.

  12. Synthesis and Characterization of Mesoporous Silica Functionalized with Calix[4]arene Derivatives

    PubMed Central

    Alahmadi, Sana M.; Mohamad, Sharifah; Maah, Mohd Jamil

    2012-01-01

    This work reports a new method to covalently attach calix[4]arene derivatives onto MCM-41, using a diisocyanate as a linker. The modified mesoporous silicates were characterized by fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA) and elemental analysis. The FTIR spectra and TGA analysis verified that the calix[4]arene derivates are covalently attached to the mesoporous silica. The preservation of the MCM-41 channel system was checked by X-ray diffraction and nitrogen adsorption analysis. PMID:23202977

  13. Double heteroatom functionalization of arenes using benzyne three-component coupling.

    PubMed

    García-López, José-Antonio; Çetin, Meliha; Greaney, Michael F

    2015-02-01

    Arynes participate in three-component coupling reactions with N, S, P, and Se functionalities to yield 1,2-heteroatom-difunctionalized arenes. Using 2-iodophenyl arylsulfonates as benzyne precursors, we could effectively add magnesiated S-, Se-, and N-nucleophilic components to the strained triple bond. In the same pot, addition of electrophilic N, S, or P reagents and a copper(I) catalyst trapped the intermediate aryl Grignard to produce a variety of 1,2-difunctionalized arenes. PMID:25580700

  14. Applications of biocatalytic arene ipso,ortho cis-dihydroxylation in synthesis.

    PubMed

    Lewis, Simon E

    2014-03-18

    The dearomatising dihydroxylation of aromatic molecules mediated by arene dioxygenase enzymes can provide cyclohexadiene-diols that are versatile starting materials for organic synthesis. Whereas oxidation of a substituted arene to give its ortho,meta-dihydrodiol has been demonstrated for numerous substrates and dioxygenases, formation of ipso,ortho-dihydrodiols has historically been underutilised in comparison. This feature article presents a chronological account of reported uses of such diols.

  15. [Study on the inclusion behavior of p-sulphonatocalix[4]arene with acridine by spectrofluorometric titrations].

    PubMed

    Zhou, Yun-You; Lu, Qin; Liu, Chun; She, Shi-Ke; Yang, Xu-Lai; Wang, Lun

    2006-09-01

    p-sulphonatocalix[4] arene (1) was prepared according to the literature, and spectrofluorometric titrations were performed to investigate the inclusion behavior of (1) and acridine in citrate buffer solution (pH 5.92, 0.1 mol x L(-1)) at different temperatures. It was found that in definite concentration range, the emission peak of acridine exhibited a slight red shift and th fluorescence intensity decreased when (1) was added. They form stable host-guest complex, and the stoichiometry of the inclusion complex is 1 : 1. The stability constants of the inclusion complex at 15.0 degrees C, 20.0, 25.0 and 30.0 degrees C were determined as 3.08 x 10(5), 4.45 x 10(4), 2.58 x 10(4) and 8.90 x 10(3), respectively. The thermodynamic parameters of inclusion process, deltaG, deltaH and deltaS, were determined. The experimental results indicated that the inclusion process was an exothermic and enthalpy-driven process. It was found that the stability constants descended when temperature rose. The most probable pattern of the inclusion complex between (1) and acridine was proposed as: acridine partially goes into the cavity of (1), and the protonated N atom and the negatively charged sulphonyl group bond firmly owing to strong electrostatic interaction. With the main contribution of electrostatic interaction and the assistance of Van de Waals and hydrophobic interaction, the host and the guest molecules form 1 : 1 supramolecular complex.

  16. Kinetic and equilibrium lithium acidities of arenes: theory and experiment.

    PubMed

    Streitwieser, Andrew; Shah, Kamesh; Reyes, Julius R; Zhang, Xingyue; Davis, Nicole R; Wu, Eric C

    2010-08-26

    Kinetic acidities of arenes, ArH, measured some time ago by hydrogen isotope exchange kinetics with lithium cyclohexylamide (LiCHA) in cyclohexylamine (CHA) show a wide range of reactivities that involve several electronic mechanisms. These experimental reactivities give an excellent Brønsted correlation with equilibrium lithium ion pair acidities (pK(Li)) derived as shown recently from computations of ArLi.2E (E = dimethyl ether). The various electronic mechanisms are well modeled by ab initio HF calculations with modest basis sets. Additional calculations using NH(3) as a model for CHA further characterize the TS of the exchange reactions. The slopes of Brønsted correlations of ion pair systems can vary depending on the nature of the ion pairs.

  17. Pillar-Shaped Macrocyclic Hosts Pillar[n]arenes: New Key Players for Supramolecular Chemistry.

    PubMed

    Ogoshi, Tomoki; Yamagishi, Tada-Aki; Nakamoto, Yoshiaki

    2016-07-27

    In 2008, we reported a new class of pillar-shaped macrocyclic hosts, known as "pillar[n]arenes". Today, pillar[n]arenes are recognized as key players in supramolecular chemistry because of their facile synthesis, unique pillar shape, versatile functionality, interesting host-guest properties, and original supramolecular assembly characteristics, which have resulted in numerous electrochemical and biomedical material applications. In this Review, we have provided historical background to macrocyclic chemistry, followed by a detailed discussion of the fundamental properties of pillar[n]arenes, including their synthesis, structure, and host-guest properties. Furthermore, we have discussed the applications of pillar[n]arenes to materials science, as well as their applications in supramolecular chemistry, in terms of their fundamental properties. Finally, we have described the future perspectives of pillar[n]arene chemistry. We hope that this Review will provide a useful reference for researchers working in the field and inspire discoveries concerning pillar[n]arene chemistry. PMID:27337002

  18. Calix[4]arenes of aluminum and gallium with benzimidazolyl ligands: steric control of the conformation via substitution on the ligand.

    PubMed

    Rufino-Felipe, Ernesto; Muñoz-Hernández, Miguel-Ángel; Saucedo-Azpeitia, Hugo F; Cortes-Llamas, Sara A

    2012-12-01

    Complexes [bzimAlR(2)](4) [bzim = benzimidazolate; R = Et (2), (i)Bu (3)], [mbzimAlR(2)](4) [mbzim = 2-methylbenzimidazolate; R = Et (6), (i)Bu (7)], [dmbzimAlR(2)](4) [dmbzim = 5,6-dimethylbenzimidazolate; R = Me (9), Et (10), (i)Bu (11)], and [tmbzimAlR(2)](4) [tmbzim = 2,5,6-trimethylbenzimidazolate; R = Me (12), Et (13), (i)Bu (14)] have been prepared via alkane elimination and coordinative self-assembly upon the reaction of benzimidazole ligands with aluminum alkyls in benzene, toluene, or xylene. Characterization of the complexes was achieved by spectroscopic methods, microanalysis, and X-ray crystallography of 2, 7, 10, 11, 13, and 14. The complexes reported herein and the aluminum and gallium analogues 1, 4, 5, and 8 reported in a previous paper (1) are predominantly tetranuclear aggregates related to calix[4]arenes in which the benzimidazolyl ligands bind two metal atoms in a η(1):η(1) fashion. X-ray crystallography demonstrates that modulation of the conformation adopted by these metallacalix[4]arenes is achieved by proper substitution on the C atom at the 2 position of the benzimidazolyl ligand. An H substituent for 1, 2, 4, 10, and 11 favors a chair conformation with a small cavity and approximate C(2h) symmetry, while a CH(3) substituent for 5, 7, 8, 13, and 14 introduces enough repulsion to switch the conformation to a 1,3-alternate or double cone with a concomitant larger cavity and approximate C(2v) symmetry.

  19. A route for lignin and bio-oil conversion: dehydroxylation of phenols into arenes by catalytic tandem reactions.

    PubMed

    Wang, Xingyu; Rinaldi, Roberto

    2013-10-25

    Finding a workaround: The conversion of lignin into low-boiling-point arenes instead of high-boiling-point phenols could greatly facilitate conventional refinery processes. A new procedure for the depolymerization of lignin and simultaneous conversion phenols into arenes is described. The method can also be rendered as a fundamental finding for the upgrade of bio-oils to arenes under mild conditions. PMID:24030931

  20. Arenal-type pyroclastic flows: A probabilistic event tree risk analysis

    NASA Astrophysics Data System (ADS)

    Meloy, Anthony F.

    2006-09-01

    A quantitative hazard-specific scenario-modelling risk analysis is performed at Arenal volcano, Costa Rica for the newly recognised Arenal-type pyroclastic flow (ATPF) phenomenon using an event tree framework. These flows are generated by the sudden depressurisation and fragmentation of an active basaltic andesite lava pool as a result of a partial collapse of the crater wall. The deposits of this type of flow include angular blocks and juvenile clasts, which are rarely found in other types of pyroclastic flow. An event tree analysis (ETA) is a useful tool and framework in which to analyse and graphically present the probabilities of the occurrence of many possible events in a complex system. Four event trees are created in the analysis, three of which are extended to investigate the varying individual risk faced by three generic representatives of the surrounding community: a resident, a worker, and a tourist. The raw numerical risk estimates determined by the ETA are converted into a set of linguistic expressions (i.e. VERY HIGH, HIGH, MODERATE etc.) using an established risk classification scale. Three individually tailored semi-quantitative risk maps are then created from a set of risk conversion tables to show how the risk varies for each individual in different areas around the volcano. In some cases, by relocating from the north to the south, the level of risk can be reduced by up to three classes. While the individual risk maps may be broadly applicable, and therefore of interest to the general community, the risk maps and associated probability values generated in the ETA are intended to be used by trained professionals and government agencies to evaluate the risk and effectively manage the long-term development of infrastructure and habitation. With the addition of fresh monitoring data, the combination of both long- and short-term event trees would provide a comprehensive and consistent method of risk analysis (both during and pre-crisis), and as such

  1. Binding behaviors of p-sulfonatocalix[4]arene with gemini guests.

    PubMed

    Zhao, Hong-Xia; Guo, Dong-Sheng; Liu, Yu

    2013-02-14

    A dozen of homoditopic cations, possessing different spacer lengths and rigidities, as well as sizes, shapes, and charges of terminal groups, were synthesized as candidate gemini guests for the complexation of p-sulfonatocalix[4]arenes (SC4A). The 12 gemini guests are divided into five species according to the different terminal groups: imidazolium (G1-G3), pyridinium (G4-G6), quinolinium (G7), viologen (G8-G11), and 1,4-diazabicyclo[2.2.2]octane (DBO, G12). Their binding structures and stoichiometries with SC4A were examined by NMR spectroscopy, which is helpful to construct diverse highly ordered assemblies. The obtained results show that the length of the linkers, as well as the charge numbers on the end groups have a pronounced effect on the binding stoichiometry, whereas the size and shape of the terminal groups have no significant influence. Furthermore, both the stability constants and thermodynamic parameters of SC4A with the terminal subunits were determined by the isothermal titration calorimetry experiments, which are valuable to understand the binding behavior, giving quantitatively deep insight.

  2. Reversible Nanoparticle-Micelle Transformation of Ionic Liquid-Sulfonatocalix[6]arene Aggregates.

    PubMed

    Wintgens, Véronique; Miskolczy, Zsombor; Guigner, Jean-Michel; Amiel, Catherine; Harangozó, József G; Biczók, László

    2015-06-23

    The effect of temperature and NaCl concentration variations on the self-assembly of 1-methyl-3-tetradecylimidazolium (C14mim(+)) and 4-sulfonatocalix[6]arene (SCX6) was studied by dynamic light scattering and isothermal calorimetric methods at pH 7. Inclusion complex formation promoted the self-assembly to spherical nanoparticles (NP), which transformed to supramolecular micelles (SM) in the presence of NaCl. Highly reversible, temperature-responsive behavior was observed, and the conditions of the NP-SM transition could be tuned by the alteration of C14mim(+):SCX6 mixing ratio and NaCl concentration. The association to SM was always exothermic with enthalpy independent of the amount of NaCl. In contrast, NPs were produced in endothermic process at low temperature, and the enthalpy change became less favorable upon increase in NaCl concentration. The NP formation was accompanied by negative molar heat capacity change, which further diminished when NaCl concentration was raised. PMID:26034843

  3. Solvent extraction of Li+, H3O+ and NH4+ into nitrobenzene by using sodium dicarbollylcobaltate and calix[4]arene-bis(t-octylbenzo-18-crown-6)

    SciTech Connect

    Makrlik, Emanuel; Selucky, P.; Vanura, Petr; Moyer, Bruce A

    2013-01-01

    From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M+ (aq) + NaL+ (nb) , ML+ (nb) + Na+ (aq) taking place in the two-phase water nitrobenzene system (M+ = Li+, H3O+, NH+4; L = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML+ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: zH3O+ < Li+ < NH+4.

  4. A high molar extinction coefficient bisterpyridyl homoleptic ru(II) complex with trans-2-methyl-2-butenoic acid functionality: potential dye for dye-sensitized solar cells.

    PubMed

    Adeloye, Adewale O; Olomola, Temitope O; Adebayo, Akinbulu I; Ajibade, Peter A

    2012-01-01

    In our continued efforts in the synthesis of ruthenium(II) polypyridine complexes as potential dyes for use in varied applications, such as the dye-sensitized solar cells (DSSCs), this work particularly describes the synthesis, absorption spectrum, redox behavior and luminescence properties of a new homoleptic ruthenium(II) complex bearing a simple trans-2-methyl-2-butenoic acid functionality as the anchoring ligand on terpyridine moiety. The functionalized terpyridine ligand: 4'-(trans-2-methyl-2-butenoic acid)-terpyridyl (L1) was synthesized by aryl bromide substitution on terpyridine in a basic reaction condition under palladium carbide catalysis. In particular, the photophysical and redox properties of the complex formulated as: bis-4'-(trans-2-methyl-2-butenoic acid)-terpyridyl ruthenium(II) bis-hexafluorophosphate [Ru(L1)(2)(PF(6))(2)] are significantly better compared to those of [Ru(tpy)(2)](2+) and compare well with those of the best emitters of Ru(II) polypyridine family containing tridentate ligands. Reasons for the improved photophysical and redox properties of the complex may be attributed partly to the presence of a substituted α,β-unsaturated carboxylic acid moiety leading to increase in the length of π-conjugation bond thereby enhancing the MLCT-MC (Metal-to-ligand-charge transfer-metal centred) energy gap, and to the reduced difference between the minima of the excited and ground states potential energy surfaces.

  5. A High Molar Extinction Coefficient Bisterpyridyl Homoleptic Ru(II) Complex with trans-2-Methyl-2-butenoic Acid Functionality: Potential Dye for Dye-Sensitized Solar Cells

    PubMed Central

    Adeloye, Adewale O.; Olomola, Temitope O.; Adebayo, Akinbulu I.; Ajibade, Peter A.

    2012-01-01

    In our continued efforts in the synthesis of ruthenium(II) polypyridine complexes as potential dyes for use in varied applications, such as the dye-sensitized solar cells (DSSCs), this work particularly describes the synthesis, absorption spectrum, redox behavior and luminescence properties of a new homoleptic ruthenium(II) complex bearing a simple trans-2-methyl-2-butenoic acid functionality as the anchoring ligand on terpyridine moiety. The functionalized terpyridine ligand: 4′-(trans-2-methyl-2-butenoic acid)-terpyridyl (L1) was synthesized by aryl bromide substitution on terpyridine in a basic reaction condition under palladium carbide catalysis. In particular, the photophysical and redox properties of the complex formulated as: bis-4′-(trans-2-methyl-2-butenoic acid)-terpyridyl ruthenium(II) bis-hexafluorophosphate [Ru(L1)2(PF6)2] are significantly better compared to those of [Ru(tpy)2]2+ and compare well with those of the best emitters of Ru(II) polypyridine family containing tridentate ligands. Reasons for the improved photophysical and redox properties of the complex may be attributed partly to the presence of a substituted α,β-unsaturated carboxylic acid moiety leading to increase in the length of π-conjugation bond thereby enhancing the MLCT-MC (Metal-to-ligand-charge transfer-metal centred) energy gap, and to the reduced difference between the minima of the excited and ground states potential energy surfaces. PMID:22489165

  6. (Pentamethylcyclopentadienyl)ruthenium complexes. 6. (Pentamethylcyclopentadienyl)(polyarene)ruthenium cations. Synthesis and electrochemical reaction

    SciTech Connect

    Koelle, U.; Wang, Maja Hong )

    1990-01-01

    By treatment of the alkoxo complex (Cp{sup *}Ru(OMe)){sub 2} with acid or trimethylsilyl trifluoromethanesulfonate in the presence of a polycyclic arene, the monocations Cp{sup *}Ru(arene){sup +} (arene = naphthalene ((1){sup +}), phenanthrene ((2){sup +}), pyrene ((3){sup +}), anthracene ((4){sup +})) and dications (Cp{sup *}Ru){sub 2}(arene){sup 2+} (arene = phenanthrene ((5){sup 2+}), pyrene ((6){sup 2+}), and anthracene ((7){sup 2+})) were synthesized. Electrochemistry (cyclic voltammetry) in dichloromethane or propylene carbonate shows all these complexes, in contrast to the case for (Cp or Cp{sup *})Ru(arene) (Cp = {eta}{sup 5}-C{sub 5}H{sub 5}, Cp{sup *} = {eta}{sup 5}-C{sub 5}Me{sub 5}) cations featuring an unfused aromatic ligand, to be reducible. Some of the electron couples are chemically reversible. Potentials and peak current ratios are discussed in terms of interaction of the Cp{sup *}Ru units and of stabilization of the reduction products.

  7. Recent advances in pillar[n]arenes: synthesis and applications based on host-guest interactions.

    PubMed

    Yang, Kui; Pei, Yuxin; Wen, Jia; Pei, Zhichao

    2016-07-19

    Pillar[n]arenes (n = 5-15) are a novel class of macrocyclic molecules with hydroquinone as the repeating unit linked by methylene bridges at para-positions. Introduced by T. Ogoshi for the first time in 2008, pillararenes have attracted increasing interest and have been widely studied during the last eight years, due to their unique structural advantages as host molecules, such as symmetrical rigid architecture, electron-rich cavities and facile functional modification. In this review, we first describe the syntheses of pillar[n]arenes including cyclooligomerization of pillar[n]arenes and modification of pillar[n]arenes after cyclooligomerization, summarising almost twenty different kinds of guest motifs and dividing them into three types: cationic, neutral and anionic motifs. The main section of this review examines the applications of pillar[n]arenes based on the host-guest interactions in different research fields, including biology, materials science and environmental science. Finally, future research directions and potential for novel applications are discussed. PMID:27332040

  8. Pyroclastic flow hazard at Arenal volcano, Costa Rica: scenarios and assessment

    NASA Astrophysics Data System (ADS)

    Oramas-Dorta, Delioma; Cole, Paul D.; Wadge, Geoff; Alvarado, Guillermo E.; Soto, Gerardo J.

    2012-12-01

    The present work provides a comprehensive understanding of the evolution of pyroclastic flow hazard at Arenal volcano, Costa Rica, during the recent period of volcanic activity. It uses the geophysical flow model TITAN2D to analyze and summarize pyroclastic flow hazard patterns associated with the topographic development of the volcanic edifice ("radial hazard pattern") and to an observed evolution in the nature of pyroclastic flows at Arenal ("concentric hazard pattern"). In this regard, a new classification of pyroclastic flows of gravitational origin at Arenal is proposed and characterized, presenting different levels of associated hazardousness. TITAN2D has been used as a basis to produce pyroclastic flow hazard maps for two defined scenarios: a "current" hazard scenario, considered as being fairly representative of the present-day situation at Arenal; and another scenario which is thought could represent a stage in future pyroclastic flow hazard where crater C has largely engulfed crater D as a result of topographic change. These two maps show significantly different hazard distributions, and demonstrate the need for frequent updates of hazard assessments in this and other similarly dynamic volcanic settings. In the case of Arenal, this implies a need for regularly updating the topographic models of the volcano to capture topographic changes that impact the distribution of volcanic flow hazard. Furthermore, this work provides a detailed evaluation of TITAN2D regarding its suitability to form the basis of such hazard assessments.

  9. The influence of arene-ring size on stacking interaction with canonical base pairs

    NASA Astrophysics Data System (ADS)

    Formánek, Martin; Burda, Jaroslav V.

    2014-04-01

    Stacking interactions between aromatic molecules (benzene, p-cymene, biphenyl, and di- and tetra-hydrogen anthracene) and G.C and A.T canonical Watson-Crick (WC) base pairs are explored. Two functionals with dispersion corrections: ω-B97XD and B3LYP-D3 are used. For a comparison also the MP2 and B3LYP-D3/PCM methods were used for the most stable p-cymene…WC geometries. It was found that the stacking interaction increases with the size of π-conjugation system. Its extent is in agreement with experimental finding on anticancer activity of Ru(II) piano-stool complexes where intercalation of these aromatic molecules should play an important role. The explored structures are considered as ternary system so that decomposition of the interaction energy to pairwise and non-additivity contributions is also examined.

  10. Direct access to pyrazolo(benzo)thienoquinolines. Highly effective palladium catalysts for the intramolecular C-H heteroarylation of arenes.

    PubMed

    Churruca, Fátima; Hernández, Susana; Perea, María; SanMartin, Raul; Domínguez, Esther

    2013-02-18

    A short and atom-efficient strategy to obtain a series of pyrazolo(benzo)thienoquinolines is developed. Alternative catalytic systems for the key intramolecular direct heteroarylation of arenes are presented and include the first example of C-H (hetero)arylation of (hetero)arenes catalyzed by very low catalyst loadings of a palladium source. PMID:23320258

  11. CALIX[4]ARENE C-99 INHIBITS MYOSIN ATPase ACTIVITY AND CHANGES THE ORGANIZATION OF CONTRACTILE FILAMENTS OF MYOMETRIUM.

    PubMed

    Labyntseva, R D; Bevza, A A; Lul'ko, A O; Cherenok, S O; Kalchenko, V I; Kosterin, S O

    2015-01-01

    Calix[4]arenes are cup-like macrocyclic (polyphenolic) compounds, they are regarded as promising molecular "platforms" for the design of new physiologically active compounds. We have earlier found that calix[4]arene C-99 inhibits the ATPase activity of actomyosin and myosin subfragment-1 of pig uterus in vitro. The aim of this study was to investigate the interaction of calix[4]arene C-99 with myosin from rat uterine myocytes. It was found that the ATPase activity of myosin prepared from pre-incubated with 100 mM of calix[4]arene C-99 myocytes was almost 50% lower than in control. Additionally, we have revealed the effect of calix[4]arene C-99 on the subcellular distribution of actin and myosin in uterus myocytes by the method of confocal microscopy. This effect can be caused by reorganization of the structure of the contractile smooth muscle cell proteins due to their interaction with calix[4]arene. The obtained results demonstrate the ability of calix[4]arene C-99 to penetrate into the uterus muscle cells and affect not only the myosin ATPase activity, but also the structure of the actin and myosin filaments in the myometrial cells. Demonstrated ability of calix[4]arene C-99 can be used for development of new pharmacological agents for efficient normalization of myometrial contractile hyperfunction.

  12. Calix[4]arene C-90 selectively inhibits Ca2+,Mg2+-ATPase of myometrium cell plasma membrane.

    PubMed

    Veklich, T A; Shkrabak, A A; Slinchenko, N N; Mazur, I I; Rodik, R V; Boyko, V I; Kalchenko, V I; Kosterin, S A

    2014-05-01

    The supramolecular compound calix[4]arene C-90 (5,11,17,23-tetra(trifluoro)methyl(phenylsulfonylimino)-methylamino-25,26,27,28-tetrapropoxycalix[4]arene) is shown to efficiently inhibit the ATP hydrolase activity of Ca2+,Mg2+-ATPase in the myometrium cell plasma membrane fraction and also in a preparation of the purified enzyme solubilized from this subcellular fraction. The inhibition coefficient I0.5 values were 20.2 ± 0.5 and 58.5 ± 6.4 µM for the membrane fraction and the solubilized enzyme, respectively. The inhibitory effect of calix[4]arene C-90 was selective comparatively to other ATPases localized in the plasma membrane: calix[4]arene C-90 did not influence the activities of Na+,K+-ATPase and "basal" Mg2+-ATPase. The inhibitory effect of calix[4]arene C-90 on the Ca2+,Mg2+-ATPase activity was associated with the cooperative action of four trifluoromethylphenylsulfonylimine (sulfonylamidine) groups oriented similarly on the upper rim of the calix[4]arene macrocycle (the calix[4]arene "bowl"). The experimental findings seem to be of importance for studies, using calix[4]arene C-90, of membrane mechanisms of regulation of calcium homeostasis in smooth muscle cells and also for investigation of the participation of the plasma membrane Ca2+-pump in control of electro- and pharmacomechanical coupling in myocytes.

  13. Rhodium(II)-catalyzed alkyne amination of homopropargylic sulfamate esters: stereoselective synthesis of functionalized norcaradienes by arene cyclopropanation.

    PubMed

    Brawn, Ryan A; Zhu, Kaicheng; Panek, James S

    2014-01-01

    A rhodium(II) catalyzed nitrene-alkyne cycloaddition of stereochemically well-defined homopropargylic ethers is followed by arene cyclopropanation to afford unique tetracyclic norcaradiene products bearing a cyclic sulfamate. Products from the arene cyclopropanation (Buchner reaction) can be converted to fused cycloheptatrienes via a ring enlarging electrocyclization after nucleophilic ring opening of the cyclic sulfamate ester.

  14. Trifluoromethylation of arenes and heteroarenes by means of photoredox catalysis

    PubMed Central

    Nagib, David A.; MacMillan, David W. C.

    2012-01-01

    Modern drug discovery relies on the continual development of synthetic methodology to address the many challenges associated with the design of new pharmaceutical agents1. One such challenge arises from the enzymatic metabolism of drugs in vivo by cytochrome P450 oxidases, which use single-electron oxidative mechanisms to rapidly modify small molecules to facilitate their excretion2. A commonly used synthetic strategy to protect against in vivo metabolism involves the incorporation of electron-withdrawing functionality, such as the trifluoromethyl (CF3) group, into drug candidates3. The CF3 group enjoys a privileged role in the realm of medicinal chemistry because its incorporation into small molecules often enhances efficacy by promoting electrostatic interactions with targets, improving cellular membrane permeability, and increasing robustness towards oxidative metabolism of the drug4–6. Although common pharmacophores often bear CF3 motifs in an aromatic system, access to such analogues typically requires the incorporation of the CF3 group, or a surrogate moiety, at the start of a multi-step synthetic sequence. Here we report a mild, operationally simple strategy for the direct trifluoromethylation of unactivated arenes and heteroarenes through a radical-mediated mechanism using commercial photocatalysts and a household light bulb. We demonstrate the broad utility of this transformation through addition of CF3 to a number of heteroaromatic and aromatic systems. The benefit to medicinal chemistry and applicability to late-stage drug development is also shown through examples of the direct trifluoromethylation of widely prescribed pharmaceutical agents. PMID:22158245

  15. Improvement of catalytic activity of lipase in the presence of calix[4]arene valeric acid or hydrazine derivative.

    PubMed

    Akoz, Enise; Sayin, Serkan; Kaplan, Selcuk; Yilmaz, Mustafa

    2015-03-01

    Sol-gel encapsulation is a simple but powerful method to enhance the enantioselectivity of lipase-catalyzed transformations in an isooctane/aqueous buffer solution. Candida rugosa lipase was encapsulated according to a sol-gel procedure in the presence and absence of calix[4]arene hydrazine or carboxylic acid derivatives with Fe3O4 magnetic nanoparticles as an additive. The activity of the encapsulated lipases was evaluated for the enantioselective hydrolysis of racemic Naproxen methyl ester and the hydrolysis of p-Nitrophenylpalmitate. The results indicate that the encapsulated lipase without calix[4]arene derivative has lower conversion and enantioselectivity compared to the encapsulated lipase with calix[4]arene derivative. It was found that the calix[4]arene hydrazine and carboxylic acid-based encapsulated lipases have excellent activity and enantioselectivity (E >300) compared to encapsulated lipase without the calix[4]arene derivatives.

  16. Impact of the uranium (VI) speciation in mineralised urines on its extraction by calix[6]arene bearing hydroxamic groups used in chromatography columns.

    PubMed

    Baghdadi, S; Bouvier-Capely, C; Ritt, A; Peroux, A; Fevrier, L; Rebiere, F; Agarande, M; Cote, G

    2015-11-01

    Actinides determination in urine samples is part of the analyses performed to monitor internal contamination in case of an accident or a terrorist attack involving nuclear matter. Mineralisation is the first step of any of these analyses. It aims at reducing the sample volume and at destroying all organic compounds present. The mineralisation protocol is usually based on a wet ashing step, followed by actinides co-precipitation and a furnace ashing step, before redissolution and the quantification of the actinides by the appropriate techniques. Amongst the existing methods to perform the actinides co-precipitation, alkali-earth (typically calcium) precipitation is widely used. In the present work, the extraction of uranium(VI), plutonium(IV) and americium(III) from the redissolution solutions (called "mineralised urines") on calix[6]arene columns bearing hydroxamic groups was investigated as such an extraction is a necessary step before their determination by ICP-MS or alpha spectrometry. Difficulties were encountered in the transfer of uranium(VI) from raw to mineralised urines, with yield of transfer ranging between 0% and 85%, compared to about 90% for Pu and Am, depending on the starting raw urines. To understand the origin of such a difficulty, the speciation of uranium (VI) in mineralised urines was investigated by computer simulation using the MEDUSA software and the associated HYDRA database, compiled with recently published data. These calculations showed that the presence of phosphates in the "mineralised urines" leads to the formation of strong uranyl-phosphate complexes (such as UO2HPO4) which compete with the uranium (VI) extraction by the calix[6]arene bearing hydroxamic groups. The extraction constant of uranium (VI) by calix[6]arene bearing hydroxamic groups was determined in a 0.04 mol L(-1) sodium nitrate solution (logK=4.86±0.03) and implemented in an extraction model taking into account the speciation in the aqueous phase. This model allowed to

  17. Impact of the uranium (VI) speciation in mineralised urines on its extraction by calix[6]arene bearing hydroxamic groups used in chromatography columns.

    PubMed

    Baghdadi, S; Bouvier-Capely, C; Ritt, A; Peroux, A; Fevrier, L; Rebiere, F; Agarande, M; Cote, G

    2015-11-01

    Actinides determination in urine samples is part of the analyses performed to monitor internal contamination in case of an accident or a terrorist attack involving nuclear matter. Mineralisation is the first step of any of these analyses. It aims at reducing the sample volume and at destroying all organic compounds present. The mineralisation protocol is usually based on a wet ashing step, followed by actinides co-precipitation and a furnace ashing step, before redissolution and the quantification of the actinides by the appropriate techniques. Amongst the existing methods to perform the actinides co-precipitation, alkali-earth (typically calcium) precipitation is widely used. In the present work, the extraction of uranium(VI), plutonium(IV) and americium(III) from the redissolution solutions (called "mineralised urines") on calix[6]arene columns bearing hydroxamic groups was investigated as such an extraction is a necessary step before their determination by ICP-MS or alpha spectrometry. Difficulties were encountered in the transfer of uranium(VI) from raw to mineralised urines, with yield of transfer ranging between 0% and 85%, compared to about 90% for Pu and Am, depending on the starting raw urines. To understand the origin of such a difficulty, the speciation of uranium (VI) in mineralised urines was investigated by computer simulation using the MEDUSA software and the associated HYDRA database, compiled with recently published data. These calculations showed that the presence of phosphates in the "mineralised urines" leads to the formation of strong uranyl-phosphate complexes (such as UO2HPO4) which compete with the uranium (VI) extraction by the calix[6]arene bearing hydroxamic groups. The extraction constant of uranium (VI) by calix[6]arene bearing hydroxamic groups was determined in a 0.04 mol L(-1) sodium nitrate solution (logK=4.86±0.03) and implemented in an extraction model taking into account the speciation in the aqueous phase. This model allowed to

  18. Rare Earth Metal Complexes of Bidentate Nitroxide Ligands: Synthesis and Electrochemistry.

    PubMed

    Kim, Jee Eon; Bogart, Justin A; Carroll, Patrick J; Schelter, Eric J

    2016-01-19

    We report rare earth metal complexes with tri- and bidentate ligands including strongly electron-donating nitroxide groups. The tridentate ligand 1,3,5-tris(2'-tert-butylhydroxylaminoaryl)benzene (H3arene-triNOx) was complexed to cerium(IV) in a 2:1 ligand-to-metal stoichiometry as Ce(Harene-triNOx)2 (1). Cyclic voltammetry of this compound showed stabilization of the tetravalent cerium cation with a Ce(IV/III) couple at E1/2 = -1.82 V versus Fc/Fc(+). On the basis of the uninvolvement of the third nitroxide group in the coordination chemistry with the cerium(IV) cation, the ligand system was redesigned toward a simpler bidentate mode, and a series of rare earth metal-arene-diNOx complexes were prepared with La(III), Ce(IV), Pr(III), Tb(III), and Y(III), [RE(arene-diNOx)2](-) ([2-RE](-), RE = La, Pr, Y, Tb) and Ce(IV)(arene-diNOx)2, where H2arene-diNOx = 1,3-bis(2'-tert-butylhydroxylaminoaryl)benzene. The core structures were isostructural throughout the series, with three nitroxide groups in η(2) binding modes and one κ(1) nitroxide group coordinated to the metal center in the solid state. In all cases except Ce(IV)(arene-diNOx)2, electrochemical analysis described two subsequent, ligand-based, quasi-reversible redox waves, indicating that a stable [N-O•] group was generated on the electrochemical time scale. Chemical oxidation of the terbium complex was performed, and isolation of the resulting complex, Tb(arene-diNOx)2·CH2Cl2 (3·CH2Cl2), confirmed the assignment of the cyclic voltammograms. Magnetic data showed no evidence of mixing between the Tb(III) states and the states of the open-shell ligand.

  19. Bismuth- and hafnium-catalyzed hydroamination of vinyl arenes with sulfonamides, carbamates, and carboxamides.

    PubMed

    Qin, Hongbo; Yamagiwa, Noriyuki; Matsunaga, Shigeki; Shibasaki, Masakatsu

    2007-01-01

    Catalytic intermolecular hydroamination of vinyl arenes is described. Our initial investigation revealed that a Bi(OTf)3/[Cu(CH3CN)4]PF6 system previously developed for catalytic intermolecular hydroamination of 1,3-dienes was suitable for hydroamination of a styrene with sulfonamides, but the substrate generality of this system was unsatisfactory. Several metals were screened to expand the substrate scope, and a new Hf(OTf)4/[Cu(CH3CN)4]PF6 system was determined to be highly suitable. The combination of Hf(OTf)4 and [Cu(CH3CN)4]PF6 efficiently promoted the hydroamination of various vinyl arenes, including less-reactive vinyl arenes with electron-withdrawing groups. This strategy was applied to sulfonamides, carbamates, and carboxamides, and products were obtained in up to 99% yield with 0.3-10 mol % catalyst loading.

  20. Langmuir and Langmuir-Blodgett Films from Amphiphilic Pillar[5]arene-Containing [2]Rotaxanes.

    PubMed

    Trinh, Thi Minh Nguyet; Nierengarten, Iwona; Holler, Michel; Gallani, Jean-Louis; Nierengarten, Jean-François

    2015-05-26

    Amphiphilic pillar[5]arene-containing [2]rotaxanes have been prepared and fully characterized. In the particular case of the [2]rotaxane incorporating a 1,4-diethoxypillar[5]arene subunit, the structure of the compound was confirmed by X-ray crystal structure analysis. Owing to a good hydrophilic/hydrophobic balance, stable Langmuir films have been obtained for these rotaxanes and the size of the peripheral alkyl chains on the pillar[5]arene subunit has a dramatic influence on the reversibility during compression-decompression cycles. Indeed, when these are small enough, molecular reorganization of the rotaxane by gliding motions are capable of preventing strong π-π interactions between neighboring macrocycles in the thin film.

  1. Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: new multivalent galectin-3 ligands

    PubMed Central

    Bernardi, Silvia; Fezzardi, Paola; Rispoli, Gabriele; Sestito, Stefania E; Sansone, Francesco

    2014-01-01

    Summary Four novel calix[4]arene-based glycoclusters were synthesized by conjugating the saccharide units to the macrocyclic scaffold using the CuAAC reaction and using long and hydrophilic ethylene glycol spacers. Initially, two galactosylcalix[4]arenes were prepared starting from saccharide units and calixarene cores which differ in the relative dispositions of the alkyne and azido groups. Once the most convenient synthetic pathway was selected, two further lactosylcalix[4]arenes were obtained, one in the cone, the other one in the 1,3-alternate structure. Preliminary studies of the interactions of these novel glycocalixarenes with galectin-3 were carried out by using a lectin-functionalized chip and surface plasmon resonance. These studies indicate a higher affinity of lactosyl- over galactosylcalixarenes. Furthermore, we confirmed that in case of this specific lectin binding the presentation of lactose units on a cone calixarene is highly preferred with respect to its isomeric form in the 1,3-alternate structure. PMID:25161726

  2. Support from Mineral and Melt-Inclusion Data for a Flux-controlled Ascent Model to Explain Longevity, Magnitude, and Composition of the Current Arenal Eruption

    NASA Astrophysics Data System (ADS)

    Streck, M. J.; Costa, F.

    2004-12-01

    Arenal volcano is famous for its ongoing, small-scale, continuous activity ever since it reawakened in July of 1968. Although activity levels have generally declined from early in the eruption to now, multiple daily explosions and associated lava production have persisted and continue to be characteristic for Arenal's current eruption. The combination of small eruption volumes, decades-long continuous activity, and eruption products that are remarkable compositionally similar, phenocryst-rich basaltic andesites provoke pressing questions about eruption driving force and petrogenetic history. Our key results indicate all eruption products exhibit significant but comparable complexities in mineral compositions, zoning and distributions requiring multi-stage mixing. Bulk compositions are mostly too mafic to have crystallized the majority of ferromagnesian minerals yet appropriate liquids are preserved in melt inclusions from tephras. Furthermore, no progressive changes in zoning near rims of phenocrysts over the course of the current eruption are apparent which complicates scenarios in which one, evolving magma batch has been tapped for the last 36 years. Evidence for replenishment events with more primitive magma is often found in cpx phenocrysts in form of discrete growth bands of high Mg#, Cr-rich cpx bound by low Mg# cpx. Modeling the diffusive equilibration of Fe-Mg gradients across bands yielded times of the latest recharge within a crystal prior its eruption of < 1 to ˜200 years suggesting variable residence times of phenocrysts and that mafic recharge can closely predate eruption. Our results fit best a model in which similar basaltic andesites are repeatedly generated from mantle magma batches during their ascent as they mix with resident magmas, fractionate, and assimilate crystals. We infer that new increments of basaltic andesite are continuously blended into the eruption-feeding reservoir concurrently to the current activity. We propose that observed

  3. The Times Scale of Andesite Differentiation at Arenal Volcano, Costa Rica (1968-2003), Indicated by U-Th-Ra Disequilibria.

    NASA Astrophysics Data System (ADS)

    Tepley, F. J.; Lundstrom, C. C.; Williams, R. W.; Murrell, M. T.; Goldstein, S. J.

    2004-12-01

    Arenal Volcano in Costa Rica has continuously erupted since 1968 evolving in a complex fashion involving crystal fractionation, magma mixing, degassing, and wall-rock interaction (Reagan et al., 1987; Cigolini, 1998). We have measured trace-element concentrations and U-series disequilibria in whole rocks and mineral separates (pyroxene, plagioclase, magnetite) over the course of the eruption from 1968 to 2003 by ICP-MS, TIMS and PIMMS techniques. Whole rock and mineral separate analyses (n>20) show only minor variation in (230Th)/(232Th) (1.10 to 1.18). In contrast, (230Th)/(238U) range from 0.91 to 1.04 reflecting the moderate spread in Th/U. Th/U consistently change from low values in the early samples (2.4) to a constant, higher value from 1986 to present (2.65). The observed U-Th disequilibria are consistent with a time scale of mineral formation being much less than that of 230Th decay (<104 years -they are not old xenocrysts) for all samples in the study. A further implication is that mantle-derived recharge magmas entering the Arenal magma chamber either have changed through time from more U-enriched to less U-enriched, or that assimilation has changed the Th/U of the system but not (230Th)/(232Th) (but the assimilant has to be very young Arenal cumulates or fortuitously have the same (230Th)/(232Th)). Ra isotope data are being analyzed to evaluate whether differentiation and mineral formation in this system operate on a time scale closer to the half life of Ra (1600 years).

  4. Pillar[5]arene as a co-factor in templating rotaxane formation.

    PubMed

    Ke, Chenfeng; Strutt, Nathan L; Li, Hao; Hou, Xisen; Hartlieb, Karel J; McGonigal, Paul R; Ma, Zhidong; Iehl, Julien; Stern, Charlotte L; Cheng, Chuyang; Zhu, Zhixue; Vermeulen, Nicolaas A; Meade, Thomas J; Botros, Youssry Y; Stoddart, J Fraser

    2013-11-13

    After the manner in which coenzymes often participate in the binding of substrates in the active sites of enzymes, pillar[5]arene, a macrocycle containing five hydroquinone rings linked through their para positions by methylene bridges, modifies the binding properties of cucurbit[6]uril, such that the latter templates azide-alkyne cycloadditions that do not occur in the presence of only the cucurbit[6]uril, a macrocycle composed of six glycoluril residues doubly linked through their nitrogen atoms to each other by methylene groups. Here, we describe how a combination of pillar[5]arene and cucurbit[6]uril interacts cooperatively with bipyridinium dications substituted on their nitrogen atoms with 2-azidoethyl- to 5-azidopentyl moieties to afford, as a result of orthogonal templation, two [4]rotaxanes and one [5]rotaxane in >90% yields inside 2 h at 55 °C in acetonitrile. Since the hydroxyl groups on pillar[5]arene and the carbonyl groups on cucurbit[6]uril form hydrogen bonds readily, these two macrocycles work together in a cooperative fashion to the extent that the four conformational isomers of pillar[5]arene can be trapped on the dumbbell components of the [4]rotaxanes. In the case of the [5]rotaxane, it is possible to isolate a compound containing two pillar[5]arene rings with local C5 symmetries. In addition to fixing the stereochemistries of the pillar[5]arene rings, the regiochemistries associated with the 1,3-dipolar cycloadditions have been extended in their constitutional scope. Under mild conditions, orthogonal recognition motifs have been shown to lead to templation with positive cooperativity that is fast and all but quantitative, as well as being green and efficient.

  5. Highly electron-poor Buchwald-type ligand: application for Pd-catalysed direct arylation of thiophene derivatives and theoretical consideration of the secondary Pd(0)-arene interaction.

    PubMed

    Korenaga, Toshinobu; Sasaki, Ryo; Shimada, Kazuaki

    2015-12-01

    Highly electron-poor SPhos ligands bearing either 2,6-bis(trifluoromethyl)-4-pyridyl (BFPy) or 3,5-(CF3)2C6H3 groups were synthesised. The former ligand highly accelerated the Pd-catalysed direct arylation of 2-propylthiophene, 2-methylthiophene or benzo[b]thiophene with only 1 mol% of the catalyst. This high catalytic activity can be attributed to a combination of electronic properties and the secondary Pd-arene interaction of BFPySPhos. The secondary interactions of SPhos, PhSPhos and BFPySPhos were optimised at the oniom(mp2/lanl2dz : b3lyp/lanl2dz) level and were further evaluated using the NBO method by DFT at the M06-2X/6-31G(d) level with LanL2DZ + ECP. The deletion energy analysis showed that the transfer of electrons from Pd to aromatic ring is the dominating factor for the secondary Pd-arene interaction of SPhos-Pd(0) complexes. Although an electron-poor BFPySPhos does not particularly favour this type of interaction, this interaction is still substantial enough to sufficiently stabilise the BFPySPhos-Pd complex. PMID:26250605

  6. Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: synthesis, characterization and highly selective sensor for Cu2+

    PubMed Central

    Nemati, Mohammad; Zadmard, Reza; Mohadjerani, Maryam

    2016-01-01

    Summary Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu2+. The receptor molecule L exhibited a pronounced selectivity towards Cu2+ over other mono and divalent ions. The formation of the complex between L and Cu2+ was evaluated by absorption, fluorescence and 1H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu2+. The 1:1 stoichiometry of the obtained complex has been determined by Job’s plot. The association constant determined by fluorescence titration was found to be 1.8 × 106 M−1. The sensor showed a linear response toward Cu2+ in the concentration range from 1 to 10 µM with a detection limit of 9.6 × 10−8 M. PMID:27559419

  7. Interaction of Cesium Ions with Calix[4]arene-bis(t-octylbenzo-18-crown-6): NMR and Theoretical Study

    SciTech Connect

    Kriz, Jaroslav; Dybal, Jiri; Vanura, Petr; Moyer, Bruce A

    2011-01-01

    Using 1H, 13C, and 133Cs NMR spectra, it is shown that calix[4]arene-bis (t-octylbenzo-18-crown-6) (L) forms complexes with one (L 3 Cs ) and two (L 3 2Cs ) Cs ions offered by cesium bis(1,2-dicarbollide) cobaltate (CsDCC) in nitrobenzene-d5. The ions interact with all six oxygen atoms in the crown-ether ring and the electrons of the calixarene aromatic moieties. According to extraction technique, the stability constant of the first complex is log nb(L 3 Cs ) = 8.8 ( 0.1. According to 133Cs NMR spectra, the value of the equilibrium constant of the second complex is log Knb (2)(L 3 2Cs ) = 6.3(0.2, i.e., its stabilization constant is log nb(L 3 2Cs ) = 15.1 ( 0.3. Self-diffusion measurements by 1H pulsed-field gradient (PFG) NMRcombined with density functional theory (DFT) calculations suggest that one DCC ion is tightly associated with L 3 Cs , decreasing its positive charge and consequently stabilizing the second complex, L 3 2Cs . Using a saturation-transfer 133Cs NMR technique, the correlation times ex of chemical exchange between L 3 Cs and L 3 2Cs as well as between L 3 2Cs and free Cs ions were determined as 33.6 and 29.2 ms, respectively.

  8. Inherently chiral calix[4]arenes via oxazoline directed ortholithiation: synthesis and probe of chiral space.

    PubMed

    Herbert, Simon A; van Laeren, Laura J; Castell, Dominic C; Arnott, Gareth E

    2014-01-01

    The diastereoselective oxazoline-directed lithiation of calix[4]arenes is reported with diastereoselective ratios of greater than 100:1 in some instances. Notably, it has been found that the opposite diastereomer can be accessed via this approach merely through the choice of an alkyllithium reagent. The inherently chiral oxazoline calix[4]arenes have also been preliminarily examined as ligands in the palladium-catalyzed Tsuji-Trost allylation reaction, returning results comparable to their planar chiral ferrocene counterparts pointing towards future application of these types of compounds.

  9. Removal of uranyl ions by p-hexasulfonated calyx[6]arene acid

    NASA Astrophysics Data System (ADS)

    Popescu (Hoştuc), Ioana-Carmen; Petru, Filip; Humelnicu, Ionel; Mateescu, Marina; Militaru, Ecaterina; Humelnicu, Doina

    2014-10-01

    Radioactive pollution is a significant threat for the people’s health. Therefore highly effective radioactive decontamination methods are required. Ion exchange, biotechnologies and phytoremediation in constructed wetlands have been used as radioactive decontamination technologies for uranium contaminated soil and water remediation. Recently, beside those classical methods the calix[n]arenic derivatives’ utilization as radioactive decontaminators has jogged attention. The present work aims to present the preliminary research results of uranyl ion sorption studies on the p-hexasulfonated calyx[6]arenic acid. The effect of temperature, contact time, sorbent amount and uranyl concentration variation on sorption efficiency was investigated. Isotherm models revealed that the sorption process fit better Langmuir isotherm.

  10. Double Heteroatom Functionalization of Arenes Using Benzyne Three‐Component Coupling†

    PubMed Central

    García‐López, José‐Antonio; Çetin, Meliha

    2015-01-01

    Abstract Arynes participate in three‐component coupling reactions with N, S, P, and Se functionalities to yield 1,2‐heteroatom‐difunctionalized arenes. Using 2‐iodophenyl arylsulfonates as benzyne precursors, we could effectively add magnesiated S‐, Se‐, and N‐nucleophilic components to the strained triple bond. In the same pot, addition of electrophilic N, S, or P reagents and a copper(I) catalyst trapped the intermediate aryl Grignard to produce a variety of 1,2‐difunctionalized arenes. PMID:25580700

  11. Double Deprotonation of Pyridinols Generates Potent Organic Electron-Donor Initiators for Haloarene-Arene Coupling.

    PubMed

    Barham, Joshua P; Coulthard, Graeme; Kane, Ryan G; Delgado, Nathan; John, Matthew P; Murphy, John A

    2016-03-24

    Transition metal-free couplings of haloarenes with arenes, triggered by the use of alkali metal alkoxides in the presence of an organic additive, are receiving significant attention in the literature. Most of the known organic additives effect coupling of iodoarenes, but not bromoarenes, to arenes. Recently it was reported that 2-pyridinecarbinol (11) extends the reaction to aryl bromides. This paper investigates the mechanism, and reports evidence for dianions derived from 11 as electron donors to initiate the reaction. It also proposes routes by which electron-poor benzoyl derivatives can be transformed into electron donors to initiate these reactions. PMID:26938924

  12. Silver(I)-Catalyzed Iodination of Arenes: Tuning the Lewis Acidity of N-Iodosuccinimide Activation.

    PubMed

    Racys, Daugirdas T; Sharif, Salaheddin A I; Pimlott, Sally L; Sutherland, Andrew

    2016-02-01

    A mild and rapid method for the iodination of arenes that utilizes silver(I) triflimide as a catalyst for activation of N-iodosuccinimide has been developed. The transformation was found to be general for a wide range of anisole, aniline, acetanilide, and phenol derivatives and allowed the late-stage iodination of biologically active compounds such as PIMBA, a SPECT imaging agent of breast cancer, and (-)-IBZM, a dopamine D2 receptor antagonist. The method was also modified for the radioiodination of arenes using a one-pot procedure involving the in situ generation of [(125)I]-N-iodosuccinimide followed by the silver(I)-catalyzed iodination. PMID:26795534

  13. Crystallization and Melt Removal at Arenal Volcano, Polytopic Vector Analysis

    NASA Astrophysics Data System (ADS)

    Hidalgo, P. J.; Vogel, T. A.; Bolge, L. L.; Ehrlich, R.; Alvarado, G. E.

    2007-12-01

    Tephra sequences ET3 and ET4 from Arenal volcano in Costa Rica have recently been interpreted to be a product of crystal fractionation by Bolge and coworkers in a series of papers (2004, 2006). The two tephra units are part of a sequence of 22 tephra units that represent a 7000 year span of the Arenal volcano activity. The tephro- stratigraphy has been described extensively by Melson (1982; 1994). The ET3 and ET4 tephras were interpreted (based on major- and trace-element, isotopic analyses of whole rocks and microchemical analyses of individual phases) as clear evidence of crystal separation by gravity settling (Bolge et al., 2004, 2006). The lower ET4 tephra sequence (andesitic and crystal poor) and the upper ET3 tephra (basaltic and crystal rich) represent an inverted snapshot of the magma chamber with contrasting geochemical properties. The ET3 sequence (deeper part of the magma chamber) has nearly constant composition with only a few elements varying stratigraphically (best represented by CaO). This is consistent with gradually decreasing amounts of melt in the upper part of ET3. The lower ET4 tephra (upper part of the magma chamber) contains large chemical gradients in both incompatible and compatible elements. In the present study we use whole-rock geochemical data from the recent tephra sequences ET3 and ET4 as inputs to Polytopic Vector Analysis (PVA) (for a review of this method see Vogel and coworkers, in press). With this method we produce a three end member solution that is consistent with crystallization of Olivine, plagioclase and pyroxene from the most mafic end member (EM1) resulting in a crystal rich mush zone. As crystallization progresses the compositions of the liquids are driven towards an intermediate end member (EM3), which has an intermediate composition liquid. At EM3 composition, rapid depletion of FeO, MgO and TiO2 by crystallization of Fe-Ti oxides, rapidly drives the liquid composition towards the silicic EM1 (incompatible element

  14. Synthesis and characterization of a Bi10O8(OAr)16 oxo-cluster supported by p-tert-butylcalix[5]arene ligands.

    PubMed

    Mendoza-Espinosa, Daniel

    2016-09-14

    Reaction of a non-dried monobenzylated [(t)BuC5(OBn)(OH)4] ligand with excess of Bi[N(SiMe3)2]3 yields a mixture of the dimeric complex 1 [Bi{(t)BuC5(OBn)(OH)}]2 in 12% yield and complex 2 [Bi10O8{(t)BuC5(OBn)(OH)}4] in 48% yield. The highly symmetric complex 2 features a Bi10O8(OAr)16 central core with tetra-, hexa- and heptacoordinated bismuth(iii) centers, and (μ2)-(μ4) bridging oxygen atoms all arranged in a I4 symmetrical pattern. Cluster 2 represents the largest bismuth oxo-cluster supported by calix[n]arene ligands reported to date. PMID:27484218

  15. Studies of morphological optical and electrical properties of the MEH-PPV/azo-calix[4]arene composite layers

    NASA Astrophysics Data System (ADS)

    Rouis, A.; Davenas, J.; Bonnamour, I.; Ben Ouada, H.

    2015-10-01

    Thin films of poly[2-methoxy-5-(20-ethylhexyloxy)-1,4 phenylenevinylene] (MEH-PPV), 5,17-bis(4-nitrophenylazo)-26,28-dihydroxy-25,27-di(ethoxycarbonylmethoxy)-calix[4]arene (azo-calix[4]arene) and MEH-PPV doped azo-calix[4]arene, with 30 wt% and 70 wt% doping ratios, were prepared from chloroform solution by spin coating technique on quartz and ITO substrates. Morphological and optical properties of the samples were investigated by scanning electron microscopy (SEM) and UV-visible spectrophotometry techniques, respectively. Further, the charge carrier transport properties and conduction mechanism of the composite MEH-PPV:azo-calix[4]arene thin films based junction were studied by using current-voltage (I-V) characteristics and dielectric spectroscopy technique. I-V characteristic of ITO/MEH-PPV:azo-calix[4]arene/Al devices showed that the space charge limited conduction (SCLC) dominates in the high voltage region. Moreover, frequency dependence of ac conductivity obeys Jonscher's universal power law. Finally, dielectric constant (ε‧), dielectric loss (ε″) and loss tangent (tan δ) were investigated as function of amount of azo-calix[4]arene in the MEH-PPV polymer matrix.

  16. Interaction of the cesium cation with calix[4]arene-bis(t-octylbenzo-18-crown-6): Extraction and DFT study

    SciTech Connect

    Makrlik, Emanuel; Toman, Petr; Vanura, Petr; Moyer, Bruce A

    2013-01-01

    From extraction experiments and c-activity measurements, the extraction constant corresponding to the equilibrium Cs+ (aq) + I (aq) + 1 (org),1Cs+ (org) + I (org) taking place in the two-phase water-phenyltrifluoromethyl sulfone (abbrev. FS 13) system (1 = calix[4]arene-bis(t-octylbenzo-18-crown-6); aq = aqueous phase, org = FS 13 phase) was evaluated as logKex (1Cs+, I) = 2.1 0.1. Further, the stability constant of the 1Cs+ complex in FS 13 saturated with water was calculated for a temperature of 25 C: log borg (1Cs+) = 9.9 0.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the cationic complex species 1Cs+ was derived. In the resulting 1Cs+ complex, the central cation Cs+ is bound by eight bond interactions to six oxygen atoms of the respective 18-crown-6 moiety and to two carbons of the corresponding two benzene rings of the parent ligand 1 via cation p interaction.

  17. Facile interchange of 3d and 4f ions in single-molecule magnets: stepwise assembly of [Mn4 ], [Mn3Ln] and [Mn2Ln2 ] cages within calix[4]arene scaffolds.

    PubMed

    Palacios, Maria A; McLellan, Ross; Beavers, Christine M; Teat, Simon J; Weihe, Høgni; Piligkos, Stergios; Dalgarno, Scott J; Brechin, Euan K

    2015-07-27

    The central Mn(II) ions in a series of calix[4]arene-stabilised butterflies can be sequentially replaced with Ln(III) ions, maintaining the structural integrity of the molecule but transforming its magnetic properties. The replacement of Mn(II) for Gd(III) allows for the examination of the transferability of spin-Hamiltonian parameters within the family as well as permitting their reliable determination. The introduction of the 4f ions results in weaker intramolecular magnetic exchange, an increase in the number of low-lying excited states, and an increase in magnetisation relaxation, highlighting the importance of exchange over single-ion anisotropy for the observation of SMM behaviour in this family of complexes. The presence of the [TM(II/III) (TBC[4])(OH)(solvent)] metalloligand (TM=transition metal, TBC=p-tBu-calix[4]arene) suggests that magnetic calix[n]arene building blocks can be employed to encapsulate a range of different "guests" within structurally robust "hosts".

  18. Novel solution-phase structures of gallium-containing pyrogallol[4]arene scaffolds**

    PubMed Central

    Kumari, Harshita; Kline, Steven R.; Wycoff, Wei G.; Paul, Rick L.; Mossine, Andrew V.; Deakyne, Carol A.; Atwood, Jerry L.

    2012-01-01

    The variations in architecture of gallium-seamed (PgC4Ga) and gallium-zinc-seamed (PgC4GaZn) C-butylpyrogallol[4]arene nanoassemblies in solution (SANS/NMR) versus the solid state (XRD) have been investigated. Rearrangement from the solid-state spheroidal to the solution-phase toroidal shape differentiates the gallium-containing pyrogallol[4]arene nanoassemblies from all other PgCnM nanocapsules studied thus far. Different structural arrangements of the metals and arenes of PgC4Ga versus PgC4GaZn have been deduced from the different toroidal dimensions, C–H proton environments and guest encapsulation of the two toroids. PGAA of mixed-metal hexamers reveals a decrease in gallium-to-metal ratio as the second metal varies from cobalt to zinc. Overall, the combined study demonstrates the versatility of gallium in directing the self-assembly of pyrogallol[4]arenes into novel nanoarchitectures. PMID:22511521

  19. Rh-catalyzed sulfonic acid group directed ortho C-H olefination of arenes.

    PubMed

    Dong, Yi; Liu, Gang

    2013-09-21

    A Rh-catalyzed ortho C-H olefination of arenes directed by a sulfonic acid group was developed with good yields and a broad reaction scope. Efficient performance of the catalyst caused this electron-poor aromatic C-H to be activated effectively and unactivated alkenes are also suitable for this reaction.

  20. Review of "Incomplete: How Middle Class Schools Aren't Making the Grade". Think Tank Review

    ERIC Educational Resources Information Center

    Baker, Bruce D.

    2011-01-01

    "Incomplete: How Middle Class Schools Aren't Making the Grade" is a new report from Third Way, a Washington, D.C.-based policy think tank. The report aims to convince parents, taxpayers and policymakers that they should be as concerned about middle-class schools not making the grade as they are about the failures of the nation's large, poor, urban…