Structural Determination of Ruthenium Complexes Containing Bi-Dentate Pyrrole-Ketone Ligands.
Ontology highlight
ABSTRACT:
SUBMITTER: Tsai YW
PROVIDER: S-EPMC6016999 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:In this work, zinc complexes containing amidopyridinate ligands substituted with different pendant arms have been described. Treatment of ligand precursors with ZnEt2 at a 1:1 ratio in THF yields zinc ethyl complexes (PyN C1Py )2(ZnEt)2 (1) and (PyN C2NMe2 )2(ZnEt)2 (2), respectively. Complexes 1 and 2 show the same geometry as a distorted tetrahedron, but adopt different coordination behaviors supported by the ligands. Complex 1 represents a rare and a non-centrosymmetric mode, which the amido group bridges two zinc centers to form a six-membered ring. However, complex 2 shows a centrosymmetric mode, which the pyridine group links to the zinc centers to form an eight-membered ring. Recrystallization of complex 2 gives an additional complex (PyN C2NMe2 )4Zn3(?3-O) (3). We attempted to prepare zinc benzyl oxide complexes but afforded only a self-assembly cubane complex Zn7Et6(OBn)8 (4). All molecular structures 1-4 are characterized depending on both single-crystal X-ray and spectroscopic data. Furthermore, their catalytic properties toward the ring opening polymerization of ?-caprolactone and L-lactide, using benzyl alcohol as the initiation reagent, are under investigation.
| S-EPMC6328485 | biostudies-other
Project description:A family of complexes of the formula trans-[RuCl2(L)(R-pybox)] (R-pybox = (S,S)-iPr-pybox, (R,R)-Ph-pybox, L = monodentate phosphonite, PPh(OR)2, and phosphinite, L = PPh2(OR), ligands) were screened in the catalytic asymmetric transfer hydrogenation of acetophenone, observing a strong influence of the nature of both the R-pybox substituents and the L ligand in the process. The best results were obtained with complex trans-[RuCl2{PPh2(OEt)}{(R,R)-Ph-pybox}] (2c), which provided high conversion and enantioselectivity (up to 96% enantiomeric excess, e.e.) for the reduction of a variety of aromatic ketones, affording the (S)-benzylalcohols.
| S-EPMC7070392 | biostudies-literature
Project description:The ruthenium(ii) polypyridyl complexes (RPCs), [(phen)2Ru(tatpp)]2+ (32+ ) and [(phen)2Ru(tatpp)Ru(phen)2]4+ (44+ ) are shown to cleave DNA in cell-free studies in the presence of a mild reducing agent, i.e. glutathione (GSH), in a manner that is enhanced upon lowering the [O2]. Reactive oxygen species (ROS) are involved in the cleavage process as hydroxy radical scavengers attenuate the cleavage activity. Cleavage experiments in the presence of superoxide dismutase (SOD) and catalase reveal a central role for H2O2 as the immediate precursor for hydroxy radicals. A mechanism is proposed which explains the inverse [O2] dependence and ROS data and involves redox cycling between three DNA-bound redox isomers of 32+ or 44+ . Cultured non-small cell lung cancer cells (H358) are sensitive to 32+ and 44+ with IC50 values of 13 and 15 μM, respectively, and xenograft H358 tumors in nude mice show substantial (∼80%) regression relative to untreated tumors when the mice are treated with enantiopure versions of 32+ and 44+ (Yadav et al. Mol Cancer Res, 2013, 12, 643). Fluorescence microscopy of H358 cells treated with 15 μM 44+ reveals enhanced intracellular ROS production in as little as 2 h post treatment. Detection of phosphorylated ATM via immunofluorescence within 2 h of treatment with 44+ reveals initiation of the DNA damage repair machinery due to the ROS insult and DNA double strand breaks (DSBs) in the nuclei of H358 cells and is confirmed using the γH2AX assay. The cell data for 32+ is less clear but DNA damage occurs. Notably, cells treated with [Ru(diphenylphen)3]2+ (IC50 1.7 μM) show no extra ROS production and no DNA damage by either the pATM or γH2AX even after 22 h. The enhanced DNA cleavage under low [O2] (4 μM) seen in cell-free cleavage assays of 32+ and 44+ is only partially reflected in the cytotoxicity of 32+ and 44+ in H358, HCC2998, HOP-62 and Hs766t under hypoxia (1.1% O2) relative to normoxia (18% O2). Cells treated with RPC 32+ show up to a two-fold enhancement in the IC50 under hypoxia whereas cells treated with RPC 44+ gave the same IC50 whether under hypoxia or normoxia.
| S-EPMC5428021 | biostudies-literature
Project description:This paper reports on the synthesis and characterization of two new polypyridyl-hydrazone Schiff bases, (E)-N'-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)thiophene-2-carbohydrazide (L1) and (E)-N'-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)furan-2-carbohydrazide (L2), and their two Ru(II) complexes of the general formula [RuCl(DMSO)(phen)(Ln)](PF6). Considering that hydrazides are a structural part of severa l drugs and metal complexes containing phenanthroline derivatives are known to interact with DNA and to exhibit antitumor activity, more potent anticancer agents can be obtained by covalently linking the thiophene acid hydrazide or the furoic acid hydrazide to a 1,10-phenanthroline moiety. These ligands and the Ru(II) complexes were characterized by elemental analyses, electronic, vibrational, 1H NMR, and ESI-MS spectroscopies. Ru is bound to two different N-heterocyclic ligands. One chloride and one S-bonded DMSO in cis-configuration to each other complete the octahedral coordination sphere around the metal ion. The ligands are very effective in inhibiting cellular growth in a chronic myelogenous leukemia cell line, K562. Both complexes are able to interact with DNA and present moderate cytotoxic activity, but 5 min of UV-light exposure increases cytotoxicity by three times.
| S-EPMC8038675 | biostudies-literature
Project description:The hydrosilylation of unsaturated compounds homogeneously catalyzed by cobalt complexes has gained considerable attention in the last years, aiming at substituting precious metal-based catalysts. In this study, the catalytic activity of well-characterized CoII and CoI complexes of the pToldpbp ligand is demonstrated in the hydrosilylation of 1-octene with phenylsilane. The CoI complex is the better precatalyst for the mentioned reaction under mild conditions, at 1 mol-% catalyst, 1 h, room temperature, and without solvent, yielding 84?% of octylphenylsilane. Investigation of the substrate scope shows lower performance of the catalyst in styrene hydrosilylation, but excellent results with allylbenzene (84?%) and acetophenone (> 99?%). This catalytic study contributes to the field of cobalt-catalyzed hydrosilylation reactions and shows the first example of catalysis employing the dpbp ligand in combination with a base metal.
| S-EPMC6472597 | biostudies-literature
Project description:The structure of ruthenium-based olefin metathesis catalyst 3 and model pi-complex 5 in solution and in the solid state are reported. The N-tolyl ligands, due to their lower symmetry than the traditional N-mesityl substituents, complicate this analysis, but ultimately provide explanation for the enhanced reactivity of 3 relative to standard catalyst 2. The tilt of the N-tolyl ring provides additional space near the ruthenium center, which is consistent with the enhanced reactivity of 3 toward sterically demanding substrates. Due to this tilt, the more sterically accessible face bears the two methyl substituents of the N-aryl rings. These experimental studies are supported by computational studies of these complexes by DFT. The experimental data provides a means to validate the accuracy of the B3LYP and M06 functionals. B3LYP provides geometries that match X-ray crystal structural data more closely, though it leads to slightly less (approximately 0.5 kcal mol-1) accuracy than M06 most likely because it underestimates attractive noncovalent interactions.
| S-EPMC2638209 | biostudies-literature
Project description:A family of three water-soluble half-sandwich arene-ruthenium complexes, depicted as C 1 -C 3 , having the general formula [Ru(p-cymene)(L)Cl]Cl has been synthesized, where L represents (1H-benzo[d]imidazol-2-yl)guanidine (L 1 ) or (benzo[d]oxazol-2-yl)guanidine (L 2 ) or (benzo[d]thiazol-2-yl)guanidine (L 3 ). The crystal structure of complex C 3 has been determined. The complexes show several absorption bands in the visible and ultraviolet regions, and they also show prominent emission in the visible region while excited near 400 nm. Studies on the interaction of ligands L 1 -L 3 and complexes C 1 -C 3 with calf thymus DNA reveal that the complexes are better DNA binders than the ligands, which is attributable to the imposed planarity of the ruthenium-bound guanidine-based ligand, enabling it to serve as a better intercalator. Molecular docking studies show that the complexes effectively bind with DNA through electrostatic and H-bonding interactions and partial intercalation of the guanidine-based ligands. Cytotoxicity studies carried out on two carcinoma cell lines (PC3 and A549) and on two non-cancer cell lines (BPH1 and WI-38) show a marked improvement in antitumor activity owing to complex formation, which is attributed to improvement in cellular uptake on complex formation. The C 1 complex is found to exhibit the most prominent activity against the PC3 cell line. Inclusion of the guanidine-based ligands in the half-sandwich ruthenium-arene complexes is found to be effective for displaying selective cytotoxicity to cancer cells and also for convenient tracing of the complexes in cells due to their prominent emissive nature.
| S-EPMC8015125 | biostudies-literature
Project description:The organometallic Ni(II) chemistry of the pyrrole-based pincer ligands, (P2RPyr)- (P2RPyr = 2,5-(R2PCH2)2C4H2N, R = Ph or Cy) is reported. Reactions of Grignard reagents with [NiCl(P2R Pyr)] afford a variety of alkyl and aryl complexes (methyl, ethyl, benzyl, phenyl, and allyl) that all display square planar geometries about nickel. The hydride complex, [NiH(P2CyPyr)], can also prepared either through treatment of [NiCl(P2CyPyr)] with LiHBEt3, or by reaction of H(P2RPyr) with [Ni(COD)2] (COD = 1,4-cyclooctadiene). Reactions of the methyl and hydride complexes with CO and CO2, respectively, evince clean migratory insertion chemistry of the Ni-C and Ni-H bonds. Both the alkyl and chloride complexes are active catalysts for the Kumada coupling of aryl chlorides and aryl or alkyl Grignard reagents at room temperature. The solid-state structures of several of the complexes are reported.
| S-EPMC3931010 | biostudies-literature
Project description:Four novel ruthenium organometallic complexes: [(??-p-cymene)Ru(4,4,4-trifluoro-1-(4-bromophenyl)-1,3-butanedione)Cl] (1), [(??-p-cymene)Ru(4,4,4-trifluoro-1-(4-bromophenyl)-1,3-butanedione)pta]PF? (2), [(??-p-cymene)Ru(4,4,4-trifluoro-1-(4-iodophenyl)-1,3-butanedione)Cl] (3) and [(??-p-cymene)Ru(4,4,4-trifluoro-1-(4-iodophenyl)-1,3-butanedione)pta]PF? (4) were synthesized and characterized by elemental analysis, infrared (IR), UV-Vis, NMR and mass spectroscopy and single-crystal X-ray diffraction. The crystal structures and spectroscopic data were compared to the previously published complexes [(??-p-cymene)Ru(4,4,4-trifluoro-1-(4-chloro-phenyl)-1,3-butanedione)Cl] (5) and [(??-p-cymene)Ru(4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butanedione)pta]PF? (6). The pairs of complexes 1 and 3 as well as 2 and 4 are isostructural, with the former crystallizing in triclinic P-1 and the latter in monoclinic P2?/c. The ruthenium(II) ion is found in a pseudo-octahedral "piano-stool" geometry in all compounds. Bond lengths and angles are consistent with other complexes of this type. Complexes 2 and 4 exhibit some moderate dynamic disorder. The lack of hydrogen bonding and major ?-? interactions means that most of intramolecular interactions are fairly weak and involve halogen atoms present. This was further confirmed by ¹H-NMR spectra, where a significant difference is observed only on the ligand near the halogen atom, following an expected trend. The combined data show that the difference in any activity depends substantially on the type of the ligand's substituted halogen atom.
| S-EPMC6155601 | biostudies-literature
Project description:The complete mol-ecule of the title compound, C8H8N2, is generated by a crystallographic center of symmetry. In the crystal, short N-H?? [H?? = 2.499?(19)?Å] inter-actions link the mol-ecules into a herringbone structure.
| S-EPMC5730307 | biostudies-other