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1.
Sangamesh A. Patil Shrishila N. Unki Prema S. Badami 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1281-1289
A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff bases derived from 5-amino-1,3,4-thiadiazole-2-thiol and 8-formyl-7-hydroxy-4-methylcoumarin/8-acetyl-7-hydroxy-4-methylcoumarin. The chelation of the complexes has been proposed in the light of analytical, spectral (IR, UV–Vis), ESI-mass, magnetic, ESR and thermal studies. The measured molar conductance values indicate that the complexes are non-electrolytes. TG and DTA provide the useful information about the coordination of water molecules to the metal ion and the stability of the complexes. TG and DTA curves show that the Co(II) complexes decomposition takes place in two stages corresponds to loss due to water molecules and Schiff base moiety. Whereas, Ni(II) and Cu(II) complexes decomposition took place in three steps corresponding to the loss of coordinated water molecules, 1,3,4-thiadiazole moiety and coumarin moiety, respectively. The Schiff bases and their complexes have been screened for their antibacterial and antifungal activities. The results of these studies show the metal complexes to be more antibacterial and antifungal as compared to the uncomplexed coumarins. 相似文献
2.
Federico A. Rojas‐Quijano Dr. Enikő Tircsóné Benyó Gyula Tircsó Dr. Ferenc K. Kálmán Dr. Zsolt Baranyai Dr. Silvio Aime Prof. A. Dean Sherry Prof. Zoltán Kovács Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(47):13188-13200
Lanthanide complexes of two tris(amide) derivatives of PCTA were synthesized and characterized. The relaxometric and luminescence properties of their lanthanide complexes were investigated as bimodal magnetic resonance (MR) and optical imaging agents. Luminescence studies show that one of the TbIII complexes dimerizes in solution at low millimolar concentrations, whereas the other may have a higher than expected coordination number in solution. The corresponding GdIII complexes display unusually high T1 relaxivities and enhanced kinetic inertness compared to GdPCTA. These features suggest that these new chelates may be suitable for in vivo applications. The fast water‐exchange rates observed for these complexes make them unsuitable as paramagnetic chemical exchange saturation transfer (PARACEST) agents. 相似文献
3.
Mn(II), Co(II), Ni(II) and Cu(II) chelates with3-phenyl-4-(p-methoxyphenylazo)-5-pyrazolone have been synthesized and were characterized by elemental and thermal analyses as well as
by IR, UV-VIS, 1HNMR, conductometric and magnetic measurements. The first stage in the thermal decomposition process of these complexes shows
the presence of water of hydration, the second denotes the removal of the coordinated water molecules. The final decomposition
products were found to be the respective metal oxides. The data of the investigated complexes suggest octahedral geometry
with respect to Co(II) 1:1, tetrahedral for Ni(II) 1:1and 2:3; square planar for Cu(II) 1:1 and 2:3; the complexes with no
coordinated water molecules (2:3) Co(II) and Mn(II) complexes are tetrahedral.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
Addition of a benzyl substituent to the macrocyclic ring of DOTA has a substantial impact on the conformational ring flipping motion of the macrocycle in the resulting LnDOTA complexes. The p-NO2-benzyl substituent in the Ln(p-NO2-Bn-DOTA)- complexes lies in an equatorial position and effectively "locks" the conformation of the ring into the deltadeltadeltadelta configuration. The presence of the p-NO2-benzyl group also increases the population of the square antiprismatic (SAP) coordination isomer for all Ln(p-NO2-Bn-DOTA)- complexes relative to that seen for the respective LnDOTA- complexes. Despite this increase in SAP isomer population, the rate of water exchange in these complexes remains comparatively fast. The kinetic and thermodynamic stabilities of the Ln(p-NO2-Bn-DOTA)- complexes are also slightly lower than the corresponding LnDOTA- complexes but appear to be sufficiently high for in vivo use. 相似文献
5.
Crystal structure and biological activities of water-soluble nickel(II) and copper(II) complexes of a Schiff-base derived from paeonol 总被引:1,自引:0,他引:1
Water-soluble Ni(II) and Cu(II) complexes of a flexible Schiff-base ligand have been synthesized, and the Ni(II) complex was
characterized by X-ray crystallography. The interactions of the two complexes with calf thymus DNA were investigated by spectroscopic
and viscosity measurements in water. The results suggest that the two complexes bind to DNA within the groove. Antioxidant
experiments against OH• and O2−• show that these two complexes have excellent ability to scavenge O2−•, and the Cu(II) complex exhibits better activity than the Ni(II) complex. 相似文献
6.
Alousy A. Blundell N.J. Burgess J. Hubbard C.D. van Eldik R. 《Transition Metal Chemistry》2002,27(3):244-252
The solvatochromism of several dicyano-bis-diimine-iron(II) complexes in various binary aqueous solvent mixtures has been established, at 25 °C. A solvent sensitivity scale has been developed for these complexes. The solvatochromic properties of two tricyano-terdentate ligand iron(II) complexes in several solvents have also been determined, as have those of a series of tetracyano-diimine complexes in DMSO–water media. These results have been analysed and systematic but varied trends of solvation were demonstrated. Piezochromic parameters for two complexes have been obtained and are discussed in the context of a solvatochromism/piezochromism correlation. 相似文献
7.
Two neutral complexes of formula [M(bpy)(cbdca)] [where M is palladium(II) (Pd(II)) or platinum(II) (Pt(II)), bpy is 2,2'-bipyridine and cbdca is anion of 1,1-cyclobutanedicarboxylic acid] have been synthesized. These water soluble complexes have been characterized by chemical analysis and conductivity measurements as well as 1H-NMR, ultraviolet-visible and infrared spectroscopy. In these complexes the ligand cbdca coordinates to Pt(II) or Pd(II) as bidentate with two oxygen atoms. They are nonelectrolyte in conductivity water. These complexes inhibit the growth of P388 lymphocytic leukemia cells and their targets are DNA. They invariably show ID50 values less than cisplatin. [Pt(bpy)(cbdca)] and [Pd(bpy)(cbdca)] have been interacted with calf thymus DNA and bind to DNA through coordinate covalent bond. In addition, the influence of binding of these complexes on the intensity of EtBr-DNA have been studied. They bind to DNA via a nonintercalating mode. 相似文献
8.
Wu DY Duan S Liu XM Xu YC Jiang YX Ren B Xu X Lin SH Tian ZQ 《The journal of physical chemistry. A》2008,112(6):1313-1321
Binding interactions and Raman spectra of water in hydrogen-bonded anionic complexes have been studied by using the hybrid density functional theory method (B3LYP) and ab initio (MP2) method. In order to explore the influence of hydrogen bond interactions and the anionic effect on the Raman intensities of water, model complexes, such as the negatively charged water clusters ((H2O)n-, n = 2 and 3), the water...halide anions (H2O...X-, X = F, Cl, Br, and I), and the water-metal atom anionic complexes (H2O...M-, M = Cu, Ag, and Au), have been employed in the present calculations. These model complexes contained different types of hydrogen bonds, such as O-H...X-, O-H...M-, O-H...O, and O-H...e-. In particular, the last one is a dipole-bound electron involved in the anionic water clusters. Our results showed that there exists a large enhancement in the off-resonance Raman intensities of both the H-O-H bending mode and the hydrogen-bonded O-H stretching mode, and the enhancement factor is more significant for the former than for the latter. The reasons for these spectral properties can be attributed to the strong polarization effect of the proton acceptors (X-, M-, O, and e-) in these hydrogen-bonded complexes. We proposed that the strong Raman signal of the H-O-H bending mode may be used as a fingerprint to address the local microstructures of water molecules in the chemical and biological systems. 相似文献
9.
《Journal of Coordination Chemistry》2012,65(12):1884-1896
A series of cobalt(II), nickel(II) and copper(II) complexes have been synthesized with Schiff bases derived from 3-substituted-4-amino-5-mercapto-1,2,4-triazole and indole-3-aldehyde in ethanol. These complexes have been characterized by elemental analyses, magnetic, spectroscopic (IR, UV-Vis, H-NMR, ESR, FAB-mass), thermal, electrochemical (CV) and solid state d.c. electrical conductivity studies. The elemental analyses confirm 1 : 2 stoichiometry of the type ML2·2H2O (M = Co/Ni) and ML2 (M=Cu). The complexes are colored solids and non-electrolytes in DMF and DMSO. Magnetic and spectral data suggest octahedral geometry for Co(II) and Ni(II) complexes and square-planar geometry for Cu(II) complexes. The presence of coordinated water in Co(II) and Ni(II) complexes was confirmed by thermal and IR data of the complexes. The complexes are insoluble in water and common organic solvents and decompose at higher temperature. All these ligands and their complexes have also been screened for antibacterial (Bacillus cereus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and antifungal activities (Aspergillus niger and Aspergillus fumigates) by the cup plate method. 相似文献
10.
Catalytic Water Oxidation by Ruthenium(II) Quaterpyridine (qpy) Complexes: Evidence for Ruthenium(III) qpy‐N,N′′′‐dioxide as the Real Catalysts
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Yingying Liu Dr. Siu‐Mui Ng Dr. Shek‐Man Yiu Dr. William W. Y. Lam Xi‐Guang Wei Dr. Kai‐Chung Lau Prof. Tai‐Chu Lau 《Angewandte Chemie (International ed. in English)》2014,53(52):14468-14471
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 CeIV‐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. 相似文献
11.
The tridentate ligand N-methyl-N,N-bis(2-pyridylmethyl)amine (L) has been employed to synthesize a dinuclear Co(II)Co(III) mixed-valence complex containing μ-methoxo and μ-carboxylato bridging ligands, [LCo(II)(μ-carboxylato)bis(μ-methoxo)Co(III)L](ClO(4))(2). In this complex, the two pseudo-octahedral Co centers have an identical ligand environment, yet the average Co-N and Co-O bond distances at the two Co ions differ significantly. Electrochemical, spectroscopic, and magnetic susceptibility measurements confirm that it belongs to a localized Class II mixed-valence system, despite the presence of a short Co···Co distance of 3.021 ?. Oxidation of this Co(II)Co(III) complex leads to formation of the corresponding Co(III)Co(III) complex that was characterized structurally and spectroscopically. In addition, dinuclear and trinuclear μ-hydroxo Co(III) complexes have been obtained in the presence of phosphate anions and absence of methanol, respectively, suggesting that an additional bridging ligand is needed to stabilize the Co(III)bis(μ-hydroxo)Co(III) fragment. Moreover, the ability of the mixed-valence Co(II)Co(III) complex and the three related Co(III) complexes to electrocatalytically oxidize water was also investigated. The observed limited water oxidation catalytic ability for these systems suggests that a multinuclear Co cluster and/or presence of O-rich ligands may be needed for the generation of efficient molecular Co-based water oxidation catalysts. 相似文献
12.
The acid dissociation constants of 4-(2'-thiazolylazo)-resorcinol (TAR) and the formation constants of the metal complexes formed by this reagent with Cu(II), Ni(II), Co(II), Zn(II) and Mn(II) have been determined potentiometrically at 25° in 50% v/v mixtures of dioxane and water. The values obtained for TAR and the metal complexes are contrasted with similar values for the reagent 4-(2'-pyridylazo)-resorcinol (PAR). Differences and similarities between the co-ordinating tendencies of these two reagents are revealed in terms of the proton displacement constant and the acid dissociation constants of the metal complexes. Evidence is presented which suggests that both TAR and PAR may act as terdentate ligands toward some bivalent metal ions. 相似文献
13.
Rai A Sengupta SK Pandey OP 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(3):789-794
Lanthanum(III) and praseodymium(III) complexes with dithiocarbamates have been synthesized by the reactions of lanthanum(III) and praseodymium(III) chloride with barium dithiocarbamate and complexes of type [LnCl(L)H2O]n have been obtained (where Ln=La(III) or Pr(III); L=barium salt of dithiocarbamate derived from glycine, L-leucine, L-valine, DL-alanine). The complexes have been characterized by elemental analysis, molar conductance, electronic absorption and fluorescence, infrared, far infrared, 1H NMR spectral studies. The presence of coordinated water molecule is inferred from thermogravimetric analysis which indicates the loss of one water molecule at 150-170 degrees C. The oscillator strength, Judd-Ofelt intensity parameter, stimulated emission cross-section, etc. have been obtained for different transitions of Pr3+. 相似文献
14.
A series of complexes of divalent transition metal ions with malonyl bis(salicyloylhydrazone) (H4MSH) have been prepared and characterized with the help of conductometric, potentiometric methods. The proton–ligand and metal–ligand stability constants were obtained pH-metrically. The electrical conductivity of solid complexes was measured at 289 K. The low molar conductance values observed for these complexes indicate that, they are non-electrolytes. They are soluble to a limited extent in DMF and DMSO. The elemental analyses of the complexes indicate that the complexes have 1:1 and 2:1 (M:L) stoichiometry with the existence of water, chloride, acetone molecules inside the coordination sphere as evidence from the IR spectral studies. Further, the complexes have been formulated by comparing C, H, N & metal analysis data, and UV–visible spectra of the complexes have been discussed. The protonation constants of the ligand and the stability constants of their metal complexes will be evaluated potentiometrically. The stoichiometric ratios of the complexes formed in solution will be evaluated applying the molar ratio (spectrophotometric) method and confirmed conductometrically. 相似文献
15.
Density functional theory B3LYP method with 6‐31G* basis set has been used to optimize the geometries of the catechin, water and catechin‐(H2O)n complexes. The vibrational frequencies have been studied at the same level to analyze these complexes. Six and eleven stable structures for the catechin‐H2O and catechin‐(H2O)2 have been found, respectively. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the systems. The interaction energies of all the complexes corrected by basis set superposition error, are from ?13.27 to ?83.56 kJ/mol. All calculations also indicate that there are strong hydrogen‐bonding interactions in catechin‐water complexes. The strong hydrogen‐bonding contributes to the interaction energies dominantly. The O–H stretching motions in all the complexes are red‐shifted relative to that of the monomer. 相似文献
16.
Icbudak H. Heren Z. Kose D. Ali Necefoglu H. 《Journal of Thermal Analysis and Calorimetry》2004,76(3):837-851
The mixed-ligand p-hydroxybenzoate complexes of Ni(II), Cu(II) and Zn(II) with nicotinamide and N,N-diethylnicotinamide were synthesized and
characterized by elemental analysis, magnetic susceptibility measurements and mass spectrometry. The thermal behavior of the
complexes was studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The infrared spectral characteristics
of the complexes are also discussed. The complexes contain two water molecules, two p-hydroxybenzoato (p-hba) and two nicotinamide (na) (or diethylnicotinamide (dena)) ligands per formula unit. In these complexes,
all ligands are coordinated to the metal ion as monodendate ligands. In Zn(II)-na and Cu(II)-dena complexes, thep-hydroxybenzoate behaves as bidentate chelating ligand through carboxylic oxygen atoms. The decomposition pathways and the
stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found
to be the respective metal oxides.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
George J.P. Britovsek Grace Y.Y. Woo Nitinan Assavathorn 《Journal of organometallic chemistry》2003,679(1):110-115
A series of water-soluble platinum(II) complexes containing bidentate imino pyridine ligands L of the general formula LPtX2 (X=Cl or Me) have been prepared. The dichloro complexes are very stable in water or dimethyl sulfoxide (DMSO), even at elevated temperatures, whereas the dimethyl complexes are less stable in these strongly polar solvents. In DMSO, an equilibrium between the complex LPtMe2 and (DMSO)2PtMe2 is observed, whereas in water decomposition is observed within 1 day at room temperature. 相似文献
18.
The complexes of chromium(III), scandium(III) and yttrium(III) formed by 1-hydroxy-2-naphthoic acid (1,2-HNA: H2L) and 3-hydroxy-2-naphthoic acid (3,2-HNA: H2L) were investigated by potentiometry and spectroscopy at 25+/-0.1 degrees C and at an ionic strength of 0.1 M KNO3 in 50% ethanol-water (v/v) medium. The stoichiometries of these three M(III) complexes formed with these hydroxy-naphthoic acids and with hydroxo ion were defined and their formation constants were determined and compared. Thus, the removing capacities of these ligands could be examined by calculating the equilibrium concentration of Cr(III) that exists in the discharge water of various industries since Cr(III) ions are the main pollutants present during waste water treatment in our city, Bursa. 相似文献
19.
Synthesis,acid hydrolysis,and Visible spectra of some bromopentakis(alkylamine)cobalt(III) complexes
Complexes of the [Co(RNH2)5Br]2+ type with R = Me, Et, n-Pr and n-Bu have been synthesized. The acid hydrolysis of these complexes have been studied in aqueous solution except for the butylamine complex, in which case the acid hydrolysis has been done in diocane-water medium because the complex is only slightly soluble in water. The acid hydrolysis of these complexes follow a pseudo-first-order reaction rate law and an SN2 mechanism with an octahedral wedge transition state has been assigned. The visible spectra of these complexes, together with [Co(NH3)5Br]2+, have been recorded and the overlapped bands have been resolved into Gaussian curves by least squares. Values of crystal field parameters Dq(RNH2), Dq(Br) and Dt in the complexes have been determined with a method originally devised by Wentworth and Piper. The calculated results agree well with those reported by other workers and a linear relationship previously observed by Mitzner et al. between Dq(RNH2) and ΔH° of proton ionization of RNH3+ ions is also found. 相似文献
20.
A variety of (diphosphine)platinum(II) carbonate complexes, (LL)Pt(CO(3)), are readily prepared from the corresponding (diphosphine)platinum dichlorides by treatment with silver carbonate in dichoromethane solution provided that water is present. This reaction also permits facile preparation of analogous (13)C-labeled complexes. The carbonate ligands in these complexes have been characterized by IR and (13)C NMR spectroscopy. Alternative preparative routes involve conversion of the precursor dichlorides to the corresponding dialkoxides or diphenoxides, followed by treatment with water and carbon dioxide. Various reaction intermediates have been spectroscopically observed in the latter syntheses. Two crystalline modifications of (Ph(2)PCH(2)CH(2)CH(2)PPh(2))Pt(CO(3)), one with and one without a dichloromethane of solvation, have been studied by single-crystal X-ray diffraction. Crystal data for PtP(2)O(3)C(28)H(26): P2(1)/c, Z = 4, T = 200 K, a = 10.362(8) ?, b = 14.743(6) ?, c = 19.183(10) ?, beta = 122.69(6) degrees. Crystal data for PtP(2)O(3)C(28)H(26).CH(2)Cl(2): P2(1)/c, Z = 4, T approximately 298 K, a = 11.744(2) ?, b = 15.526(3) ?, c = 15.866(3) ?, beta = 101.58(1) degrees. 相似文献