Home About us Contact
|
Home About us Contact | ||
|
|
||
Mixed-ligand Complexes (mixed-ligand + complex)
Selected AbstractsAn Investigation of the Reactivity of [(diimine)(dithiolato)M] Complexes Using the Fukui Functions ConceptEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2006Christodoulos Makedonas Abstract Fukui functions are widely used when investigating the reactivity of organic molecules, but rarely with metal complexes. Here, we investigate the reactivity of [(diimine)(dithiolato)M] complexes with different types of reagents and upon oxidation employing this concept. Mixed-ligand complexes of this type have a peculiar electronic description due to the mixed-metal-ligand-to-ligand charge-transfer band, which is why they are considered as very promising candidates for non-linear optical (NLO) materials and molecular photochemical devices (MPD). As a result, their reactivity is of crucial importance for their potential applications. The obtained results of f+ and f, for the neutral [(diimine)(dithiolato)M] complexes (M = Pd, Ni and Pt) not only predict that the sulfur atom is the preferable active site for electrophilic attack but also reveal the different tunability of these complexes when they are subjected to an oxidation process, in agreement with experimental results. Under the framework of the Fukui indices we also provide an alternative explanation for crystal packing that could find widespread application. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis of New Ruthenium (II) Bipyridyl Complexes and Studies on Their Photophysical and Photoelectrochemical PropertiesCHINESE JOURNAL OF CHEMISTRY, Issue 6 2003Song Lin-Qing Abstract Two new mixed-ligand ruthenium(II) complexes, Ru(dcbpy)-(LL) (NCS)2[where dcbpy = 4, 4,-dicarboxyl-2,2,-bipyridine, LL = 4,4,-bis (N -methyl-anilinomethyl)-2,2,-bipyridine (1) or 4-methyl-4,- N -methyl-anilinomethyl-2,2,-bipyridine (2)], were synthesized, and the photophysical properties of these complexes were studied. The metal-to-ligand charge transfer (MLCT) transitions of these complexes exhibited solvatochromic effect due to the existence of NCS ligands. The MLCT energies also strongly depend on the pH values of the solutions because of protonation and deprotonation of the carboxyl groups. The pKa, values of the ground state, 4.0 for 1 and 3.8 for 2, were obtained from the titration curves. The photoelectrochemical properties of 1 and 2 as sensitizers in sandwich-type solar cells have been studied. Complex 1 exhibited better photoelectrochemical behavior than complex 2 as expected. It was proved that the design of mixed-ligand complex by introducing electron donating group in one of the ligands should be a promising approach. [source] A Comparative Study of the Optical and Electroluminescent Properties of EuIII Complexes with TTA and 2-(2,-Pyridyl)azoles: The Crystal Structure of [Eu(TTA)3(PBO)]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2006Li-Hua Gao Abstract Two EuIII mixed-ligand complexes, namely [Eu(TTA)3(PBO)]and [Eu(TTA)3(PBT)] [TTA = 1,1,1-trifluoro-3-(2-thenoyl)acetonato, PBO = 2-(2,-pyridyl)-1,3-benzoxazole, and PBT = 2-(2,-pyridyl)-1,3-benzothiazole], have been synthesized. [Eu(TTA)3(PBO)] has been structurally characterized by single-crystal X-ray diffraction analysis. The complex crystallizes in the monoclinic space group C2/c. The lattice parameters are a = 41.346(4), b = 10.0538(8), c = 20.3793(16) Å, , = 110.922(2)°, Z = 8. The EuIII ion is eight-coordinate, with three bidentate TTA, anions and one bidentate N,O-chelated PBO molecule. A comparative study by UV and emission spectroscopy was carried out and electroluminescent properties of the related complexes [Eu(TTA)3(PBO)] and [Eu(TTA)3(PBT)] are reported as well. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Antibacterial, spectral and thermal aspects of drug based-Cu(II) mixed ligand complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2009G. J. Kharadi Abstract The antibiotic agent clioquinol is well known for its drug design and coordinating ability towards metal ions. Copper(II) mixed-ligand complexes of clioquinol with various uninegative bidentate ligands were prepared. The structure of the synthesized complexes was characterized using elemental analyses, infrared spectra, 1H-NMR spectra, electronic spectra, magnetic measurements, FAB mass spectrum and thermo gravimetric analyses. The kinetic parameters such as order of reaction (n) and the energy of activation (Ea) are reported using the Freeman,Carroll method. The pre-exponential factor (A), the activation entropy (,S#), the activation enthalpy (,H#) and the free energy of activation (,G#) were calculated. Complexes were also screened for their in vitro antibacterial activity against a range of Gram-positive and Gram-negative bacteria in order to set the precursors for anti-tumourigenic agent. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis, spectroscopy, thermal and biological aspect of novel six-coordinated dimeric iron(III) mixed-ligand complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2008M. N. Patel Abstract The mixed-ligand complexes of iron(III) with 1-cyclopropyl-6-fluoro-4-oxo-7-piperazin-1-yl-1,4-dihydroquinoline-3-carboxylic acid and various neutral bidentate Schiff base ligands were prepared. The structure of mixed-ligand complexes was investigated using spectral, physicochemical and elemental analyses. Biocidal activity was determined using agar plate technique against Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Salmonella typhi, Escherichia coli and Serratia marcescens. The result showed a significant increase in a biocidal activity compared with parent ligands, metal salts and standard drugs (ofloxacin, levofloxacin). DNA binding and cleavage studies were carried out using absorption titration and gel electrophoresis techniques, respectively. The binding constant of Fe(III) complexes was obtained in the range 2.5,4.0 × 104M,1. The DNA binding and cleavage efficacy were raised in mixed-ligand complexes as compared with parental ligands and metal salts. Copyright © 2008 John Wiley & Sons, Ltd. [source] Diorganotin(IV) Derivatives of Substituted Benzohydroxamic Acids with High Antitumor ActivityCHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2004Qingshan Li Abstract A series of diorganotin(IV) and dichlorotin(IV) derivatives of 4-X-benzohydroxamic acids, [HL1 (X = Cl) or HL2 (X = OCH3)] formulated as [R2SnL2] (R = Me, Et, nBu, Ph or Cl; L = L1 or L2), along with their corresponding mixed-ligand complexes [R2Sn(L1)(L2)] have been prepared and characterized by FT-IR, 1H, 13C, and 119Sn NMR spectroscopy, mass spectrometry, elemental analysis, and melting points. In addition, single-crystal X-ray diffraction analyses were carried out for [Me2SnL2] (L = L1 or L2), which show coordination structures intermediate between distorted octahedra and bicapped tetrahedra. The hydroxamate ligands are asymmetrically coordinated by the oxygen atoms, the carbonyl oxygen atom is further away from the metal center than the other oxygen atom. The complexes are stable monomeric species; most of them are soluble not only in chlorohydrocarbon solvents, but also in alcohols and hydroalcoholic solutions. In polar solvents, the mixed-ligand complexes gradually decompose into the corresponding single-ligand complex couples. The complexes exhibit in vitro antitumor activities (against a series of human tumor cell lines) which, in some cases, are identical to, or even higher than, that of cisplatin. For the dialkyltin complexes, the activity increases with the length of the carbon chain of the alkyl ligand and is higher in the case of the chloro-substituted benzohydroxamato ligand. The [nBu2Sn(L1)2] complex displays a high in vivo activity against H22 liver and BGC-823 gastric tumors, and has a relatively low toxicity. [source] | ||||||||||