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1.
The mixed‐ligand heterochelates of Cu(II) with 5‐chloro‐7‐iodo‐8‐hydroxyquinoline (clioquinol) and various uninegative bidentate ligands were prepared. The structure of mixed‐ligand heterochelates was investigated using spectral, physicochemical, elemental analysis and thermal studies. The FAB‐mass spectrum of [Cu(A2)(CQ)(H2O)2].2H2O has been carried out. Magnetic moment and reflectance spectral studies reveal that an octahedral geometry has been assigned to all the prepared heterochelates. The kinetic parameters such as order of reaction (n), the energy of activation (Ea), the pre‐exponential factor (A), the activation entropy (ΔS#), the activation enthalpy (ΔH#) and the free energy of activation (ΔG#) have been reported. The ligands, metal salts, heterochelates, control and standard drug were tested for their in‐vitro antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens and Bacillus substilis. The metal complexes exhibit good activity against bacterial strains compared with parental compounds, and moderate compared with the standard drug (clioquinol). Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
2.
A series of novel heterochelates of the type [Fe(An)(L)(H2O)2]?mH2O [where H2An = 4,4′‐(arylmethylene)bis(3‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐pyrazol‐5‐ol); aryl = 4‐nitrophenyl, m = 1 (H2A1); 4‐chlorophenyl, m = 2 (H2A2); phenyl, m = 2 (H2A3); 4‐hydroxyphenyl, m = 2 (H2A4); 4‐methoxyphenyl, m = 2 (H2A5); 4‐hydroxy‐3‐methoxyphenyl, m = 1.5 (H2A6); 2‐nitrophenyl, m = 1.5 (H2A7); 3‐nitrophenyl, m = 0.5 (H2A8); p‐tolyl, m = 1 (H2A9) and HL = 1‐cyclopropyl‐6‐fluoro‐4‐oxo‐7‐(piperazin‐1‐yl)‐1,4‐dihydroquinoline‐3‐carboxylic acid] were investigated. They were characterized by elemental analysis (FT‐IR, 1H‐ & 13C‐NMR, and electronic) spectra, magnetic measurements and thermal studies. The FAB‐mass spectrum of [Fe(A3)(L)(H2O)2]?2H2O was determined. Magnetic moment and reflectance spectral studies revealed that an octahedral geometry could be assigned to all the prepared heterochelates. Ligands (H2An) and their heterochelates were screened for their in‐vitro antibacterial activity against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Serratia marcescens bacterial strains. The kinetic parameters such as order of reaction (n), the energy of activation (Ea), the pre‐exponential factor (A), the activation entropy (ΔS#), the activation enthalpy (ΔH#) and the free energy of activation (ΔG#) are reported. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
3.
Fluorescence properties of four based derivatives [An] (where n = 1–4) and their Cu(II) heterochelates of the type [Cu(An)(CQ)(OH)]?xH2O {where A1 = 3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one, A2 = 8‐methyl‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one, A3 = 6‐methyl‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one, A4 = 8‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)‐4H‐furo[3,2‐c]chromen‐4‐one and x = 3, 2, 4, 1} were studied at room temperature. The fluorescence spectra of heterochelates show red shift, which may be due to the chelation by the ligands to the metal ion. It enhances ligand ability to accept electrons and decreases the electron transition energy. The kinetic parameters such as order of reaction (n), energy of activation (Ea), entropy (ΔS#), pre‐exponential factor (A), enthalpy (ΔH#) and Gibbs free energy (ΔG#) have been reported. The antimicrobial activity of Clioquinol and Cu(II) heterochelates have been determined and described. All the heterochelates showed a more effective antimicrobial activity than the free ligand. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
Synthesis and thermal decomposition kinetics of La(III) complexwith unsymmetrical Schiff base ligand
Y. H. Fan Z. X. Gao C. F. Bi S. T. Xie X. Zhang 《Journal of Thermal Analysis and Calorimetry》2008,91(3):919-923
A new unsymmetrical solid Schiff base (LLi) was synthesized using L-lysine, o-vanillin and 2-hydroxy-l-naphthaldehyde. Solid lanthanum(III) complex of this ligand [LaL(NO3)]NO3·2H2O have been prepared and characterized by elemental analyses, IR, UV and molar conductance. The thermal decomposition kinetics
of the complex for the second stage was studied under non-isothermal condition by TG and DTG methods. The kinetic equation
may be expressed as: dα/dt=Ae−E/RT(1−α)2. The kinetic parameters (E, A), activation entropy ΔS
# and activation free-energy ΔG
# were also gained. 相似文献
5.
Saud M. A. Katib 《Journal of Thermal Analysis and Calorimetry》2011,103(2):647-652
Thermal decomposition of Ni(II), Pd(II), and Pt(II) complexes of N-pyrimidin-2ylthiourea (AllPmTu) have been studied by TG, DTG, and DTA and by electron impact (EI) mass spectra. The complexes
have the molecular formulae as [Ni(AllPmTu)Cl2(H2O)], [Ni(AllPmTu)2Cl2(H2O)2], and [M(AllPmTu)Cl2], where M = PdII or PtII, and [Pt(AllPmTu)2]. The TG curves show that Ni(II) complexes decompose in three stages to yield NiO as a residue, while Pd(II) and Pt(II) decompose
in two stages to yield MS residues. The initial mass losses correspond to elimination of allylamine for Pd(II) and Pt(II)
complexes but, allyisothiocyanate for both Ni(II) complexes revealing that sulfur atom of thiourea part is involved in coordination
to Pd(II) and Pt(II) but does not to Ni(II). Kinetic parameters (E
#, n, ΔH
#, ΔS
#, ΔG
#) of the decomposition stages are determined and correlated with bonding and structural properties of the complexes. The EI
mass spectra of the complexes show fragments corresponding to the evolved and intermediate species. 相似文献
6.
Antibacterial,spectral and thermal aspects of some novel first transition metal‐based heterochelates
A new ligand, 5‐{[5‐(pyridine‐4‐yl)‐1,3,4‐oxadiazole‐2‐ylthio]methyl}quinoline‐8‐ol (K), was synthesized by base‐catalysed reaction of 5‐chloromethyl‐8‐hydroxy quinoline (CMQ) and 5‐(pyridine‐4‐yl)‐1,3,4‐oxadiazole‐2‐thiol. The obtained ligand K was characterized by 1H NMR, 13C NMR and IR spectroscopic techniques and reacted with transition metal salts to afford metal‐containing heterochelates. The structures of the synthesized heterochelates were characterized using elemental analyses, infrared spectra, electronic spectra, magnetic measurements, FAB mass spectrum and thermogravimetric 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 (ΔS#), the activation enthalpy (ΔH#) and the free energy of activation (ΔG#) were calculated. Heterochelates were also screened for their in vitro antibacterial activity against a range of Gram‐positive (Bacillus substilis, Staphylococcus aureus) and Gram‐negative (Escherichia coli, Serratiamarcescens) organisms. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
This article describes the synthesis, structural features, and thermal studies of novel Mn(III) heterochelates of the type
[Mn(SB
n
)(L)(H2O)]·xH2O [H2SB
n
= Nicotinic acid [1-(3-methyl-5-oxo-1-phenyl-4,5 dihydro-1H-pyrazol-4yl)-acylidene]-hydrazide where acyl = acetyl (H2SB1); benzoyl (H2SB2); propionyl (H2SB3); buteryl (H2SB4); phenyl acetyl (H2SB5); and HL = 5-Chloro-7-iodo-8-hydroxyquinoline (clioquinol)]. The heterochelates have been characterized on the basis of elemental
analyses, magnetic susceptibility measurements, cyclic voltammetric studies, (FTIR and electronic) spectra, and thermal studies.
The FAB mass spectrum of [Mn(SB1)(L)H2O]·3H2O has been carried out. The cyclic voltammetric studies reveal that quasi-reversible reduction process of Mn(III)/Mn(II) coupled
system suggesting that the ligands readily destabilize higher oxidation states of metal ion. Kinetic parameters such as order
of reaction (n) and the energy of activation (Ea) were calculated using 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 using Horowitz–Metzger equations. 相似文献
8.
The kinetics of the anation reaction of cis-diaquo-bis-oxalatochromate(III) ion by DL-alanine has been studied spectrophotometrically
in the pH range 3.8 to 7.3, where DL-alanine remains in zwitterionic form. A second-order rate law has been established. Reaction
rates in three different ethanol-water mixtures were measured. In each solvent medium the anation rate is higher as compared
to water exchange reaction at a particular temperature. The activation parameters (gDH# and ΔS#) in different ethanol-water mixtures were obtained from Eyring plots. ΔG#(ΔH# −TΔS
#) values were calculated in each solvent medium and compared with that of the isotopic water exchange process. A reaction
mechanism involving theS
N2 path has been suggested. 相似文献
9.
Zhang Anyun Hu Jingxin Zhang Xianye Wang Fangding 《Journal of Radioanalytical and Nuclear Chemistry》1998,230(1-2):235-239
The kinetics of oxidation-reduction reaction between N,N-diethylhydroxylamine (DEHAN) and nitrous acid in nitric acid solution
have been studied by spectrophotometry at 9.5°C. The rate equation is −d[HNO2]/dt=K[HNO2]·[DEHAN][HNO3] and the rate constantK=12.81 (mol/l)−2·min−1. A possible mechanism has been suggested on the basis of chemical analysis and Raman spectra. The activation energyE and the thermodynamic functions ΔH
#, ΔG
# and ΔS
# are also calculated. 相似文献
10.
Banjong Boonchom Samart Kongtaweelert 《Journal of Thermal Analysis and Calorimetry》2010,99(2):531-538
The kinetics and thermodynamics of the thermal dehydration of aluminum phosphate monohydrate, AlPO4 · H2O were studied using thermogravimetry (TG-DTG-DTA) at four heating rates in dry air atmosphere. The activation energies of
the dehydration step of AlPO4 · H2O were calculated through the methods of Friedman (FR) and Flynn–Wall–Ozawa (FWO) and the possible conversion function has
been estimated through the Achar and Li–Tang equations. The independent activation energies on extent of conversions and the
better kinetic model of the dehydration reaction for AlPO4 · H2O indicate single kinetic mechanism and the F
2.05
model as a simple n-order reaction of “chemical process or mechanism no-invoking equation”, respectively. The positive values
of ΔH# and ΔG# for the dehydration reaction show that it is endothermic and non-spontaneous process and it is connected with the introduction
of heat. The kinetic and thermodynamic functions calculated for the dehydration reaction by different techniques and methods
were found to be consistent. 相似文献
11.
Synthesis and thermal decomposition kinetics of Th(IV) complex with unsymmetrical Schiff base ligand
Fan Yuhua Bi Caifeng Liu Siquan Yang Lirong Liu Feng Ai Xiaokang 《Journal of Radioanalytical and Nuclear Chemistry》2005,266(1):89-93
Summary A new unsymmetrical Schiff base ligand (H2LLi) was synthesized using L-lysine, o-vanillin and salicylaladyde. Thorium(IV) complex of this ligand [Th(H2L)(NO3)](NO3)2.3H2O have been prepared and characterized by elemental analyses, IR, UV and molar conductance. The thermal decomposition kinetics
of the complex for the second stage was studied under non-isothermal condition by TG and DTG methods. The kinetic equation
may be expressed as: dα/dt=A.e-E/RT.1/2 (1-α).[-ln(1-α)]-1. The kinetic parameters (E, A), activation entropy ΔS1and activation free-energy ΔG1were also calculated. 相似文献
12.
《Journal of Coordination Chemistry》2012,65(3):358-372
Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes of multifunctional triaminoxime have been synthesized and characterized by elemental analyses, IR, UV–Vis spectra, magnetic moments, 1H- and 13C-NMR spectra for ligand and its Ni(II) complex, mass spectra, molar conductances, thermal analyses (DTA, DTG and TG) and ESR measurements. The IR spectral data show that the ligand is bi-basic or tri-basic tetradentate towards the metals. Molar conductances in DMF indicate that the complexes are non-electrolytes. The ESR spectra of solid copper(II) complexes [(HL)(Cu)2(Cl)2] · 2H2O (2) and [(L)(Cu)3(OH)3(H2O)6] · 7H2O (6) show axial symmetry of a d x²???y 2 ground state; however, [(HL)(Co)] (4) shows an axial type with d Z 2 ground state and manganese(II) complex [(L)(Mn)3(OH)3(H2O)6] · 4H2O (10) shows an isotropic type. The biological activity of the ligand and its metal complexes are discussed. 相似文献
13.
Complexes of 5-(phenylazo)-2-thiohydantoin (L1) and 5-(2-hydroxyphenylazo)-2-thiohydantoin (HL2) with Co(II), Ni(II) and Cu(II) salts have been synthesised and characterized by elemental analysis, conductivity, magnetic susceptibility, UV-Vis, IR, ESR and TG studies. The magnetic and spectral data suggested octahedral geometry for [L1M(OAc)2(H2O)2]·xH2O {M=Nill and Cull} and [L1CuCl2(H2O)]·H2O (dimeric form for the latter), trigonal bipyramidal geometry for [L2Co(OAc)(H2O)]·2H2O, square pyramidal geometry for [L2Ni(OAc)(H2O)]·H2O and square planar geometry for [L2CuCl]·2H2O. TG studies confirmed the chemical formulations of these complexes and showed that their thermal degradation takes place in three to five steps, depending on the type of the ligand and the geometry of the complex. The kinetic parameters (n, E#, A, ΔH#, ΔS# and ΔG#) of the thermal decomposition stages were computed using the Coats-Redfern and other standard equations and are discussed. 相似文献
14.
Hassan A. Ewais 《Transition Metal Chemistry》2009,34(5):539-547
The oxidation of [CoII(nta)(ox)(H2O)2]3− and [CoII(nta)(ph)(H2O)2]3− (nta = nitrilotriacetate, ox = oxalic acid and ph = phthalic acid) by periodate have been studied kinetically in aqueous
solution over 20–40 °C and a variety of pH ranges. The rate of oxidation of [CoII(nta)(ox)(H2O)2]3− by periodate, obeys the following equation: d[CoIII]/dt = [CoII(nta)(ox)(H2O)23−][H5IO6] {k
4
K
5 + (k
5
K
6
K
2/[H+]} while the reaction of [CoII(nta)(ph)(H2O)2]3− with periodate in aqueous acidic medium obeys the following rate law: d[CoIII]/dt = k
6
K
8[CoII]T [IVII]T/{1 + [H+]/K
7 + K
8[IVII]
T
}. Initial cobalt(III) products were formed and slowly converted to final products, fitting an inner-sphere mechanism. Thermodynamic
activation parameters have been calculated. A common mechanism for the oxidation of ternary nitrilotriacetatocobalt(II) complexes
by periodate is proposed and supported by an excellent isokinetic relationship between ΔH* and ΔS* values for these reactions. 相似文献
15.
The behaviour of 1-(2-bromoethyl) 4-nitrobenzene (1), N,N,N-triethyl-2-(4-nitrophenyl)ethanaminium bromide (2) and N,N-diethyl-N-[2-(4-nitrophenyl)ethyl]octan-1-aminium bromide (3) in the OH−-induced elimination reactions with formation of 1-nitro-4-vinylbenzene in mixtures of DMSO/H2O or CH3CN/H2O has been investigated. With all three substrates an increase in dipolar aprotic solvent content implies a limited increase
of the second-order rate constant k
OH up to ≅605, and then an exponential increase is observed. The variation of activation parameters ΔH
# and dGS
#, measured in DMSO/H2O mixtures, is parallel for 1 and 2. This similar behaviour of 1 and 2 with respect to variation in solvent composition is evidence that it is not possible to use this technique of solvent effect
for the mechanistic diagnosis of elimination reactions. 相似文献
16.
A. K. Mishra S. B. Mishra N. Manav N. K. Kaushik 《Journal of Thermal Analysis and Calorimetry》2007,90(2):509-515
Palladium(II) complexes of type [Pd(L)Cl2] [where L=2-aminopyridine-N-thiohydrazide (L1), (2-aminopyridine-N-thio)-1,3-propanediamine (L2), benzaldehyde 2-aminopyridine-N-thiohydrazone (L3) and salicylaldehyde-2-aminopyridine-N-thiohydrazone (L4)] have been synthesized. The thiohydrazide, thiodiamine and thiohydrazones can exist as thione-thiol tautomer and coordinate
as a bidentate N-S ligand. The ligands found to act in bidentate fashion.
The complexes have been characterized by elemental analysis, IR, mass, electronic, 1H NMR spectroscopic studies, and TG/DTA study. Antifungal studies of some complexes were also carried out. Various kinetic
and thermodynamic parameters like order of reaction (n), activation energy (E
a), apparent activation entropy (S
#
) and heat of reaction (ΔH) have also been carried out for one complex. 相似文献
17.
R. E. Lyon R. N. Walters S. I. Stoliarov 《Journal of Thermal Analysis and Calorimetry》2007,89(2):441-448
The present article describes the synthesis,
structural features and thermal studies of the complexes of the type [M(SB)2(H2O)2]·nH2O [where
HSB=pyridine-m-carboxaldene-o-aminobenzoic
acid and M=Mn(II), Co(II), Ni(II), Cu(II),
Zn(II) and Cd(II)]. The complexes have been characterized on the basis of
elemental analyses, magnetic susceptibility measurements, (FTIR and electronic)
spectra and thermal studies. The nature of the bonding has been discussed
on the basis of infrared spectral data. Magnetic susceptibility measurements
and electronic spectral data suggest a six-coordinated structure of these
complexes. The complexes of Mn(II), Co(II), Ni(II), Cu(II) are paramagnetic,
while Zn(II) and Cd(II) are diamagnetic in nature.
The thermal
decomposition of the complexes have been studied and indicates that not only
the crystallization and coordinated water are lost but also that the decomposition
of the ligand from the complexes is necessary to interpret the successive
mass losses. The kinetic parameters such as order of reaction (n)
and the energy of activation (E
a)
have been reported using Freeman–Carroll method. The entropy (S*), the pre-exponential factor (A),
the enthalpy (H*) and the Gibbs free energy
(G*) have been calculated. 相似文献
18.
Sudip K. Mukhopadhyay 《Transition Metal Chemistry》2008,33(6):739-743
The kinetics of the interaction of diethyldithiocarbamate (Et2DTC) with [Pt(dach)(H2O)2]2+ (dach = cis-1,2-diaminocyclohexane) have been studied spectrophotometrically as a function of [Pt(dach)(H2O)2
2+], [Et2DTC] and temperature at a particular pH (4.0). The reaction proceeds via rapid outer sphere association complex formation
followed by two slow consecutive steps. The first step involves the transformation of the outer sphere complex into an inner
sphere complex containing a Pt–S bond and one aqua ligand, while the second step involves chelation when the second aqua ligand
is replaced. The association equilibrium constant K
E and two rate constants k
1 and k
2 have been evaluated. Activation parameters for both the steps have been calculated (∆H
1
# = 66.8 ± 3.7 kJ mol−1, ∆S
1# = −81 ± 12 JK−1 mol−1 and ∆H
2# = 95.1 ± 2.8 kJ mol−1, ∆S
2# = −34.4 ± 9.1 JK−1 mol−1). The low enthalpy of activation and negative entropy of activation indicate an associative mode of activation for both the
steps. 相似文献
19.
X. P. Geng Y. N. Wu J. R. Song X. D. Geng J. W. Xing Z. M. Lei 《Journal of Thermal Analysis and Calorimetry》2006,85(3):593-600
Lead(II) complexes
of reduced glutathione (GSH) of general composition [Pb(L)(X)]·H2O
(where L=GSH; X=Cl,
NO3, CH3COO, NCS) have been
synthesized and characterized by elemental analyses, infrared spectra and
electronic spectra. Thermogravimetric (TG) and differential thermal analytical
(DTA) studies have been carried out for these complexes. Infrared spectra
indicate deprotonation and coordination of cysteinyl sulphur with metal ion.
It indicates the presence of water molecule in the complexes that has been
supported by TG/DTA. The thermal behaviour of complexes shows that water molecule
is removed in first step-followed removal of anions and then decomposition
of the ligand molecule in the subsequent steps. Thermal decomposition of all
the complexes proceeds via first order kinetics. The thermodynamic activation
parameters, such as E*, A,
ΔH*, ΔS*
and ΔG* have been calculated. The
geometry of the metal complexes has been studied with the help of molecular
modeling for energy minimization calculation. 相似文献
20.
Y. R. Zhao J. X. Dong Y. Liu S. S. Qu 《Journal of Thermal Analysis and Calorimetry》2007,90(2):565-568
The two complexes, [RE(Gly)4(Im)(H2O)](ClO4)3(s)(RE = Eu, Sm), have been synthesized and characterized. The standard molar enthalpies of reaction for the following reactions,
RECl3·6H2O(s)+4Gly(s)+Im(s)+3NaClO4(s) = =[RE(Gly)4(Im)(H2O)](ClO4)3(s)+3NaCl(s)+5H2O(l), were determined by solution-reaction colorimetry. The standard molar enthalpies of formation of the two complexes at
T = 298.15 K were derived as Δf
H
mΘ {Eu(Gly)4(Im)(H2O)}(ClO4)3(s)} = = −(3396.6±2.3) kJ mol−1 and Δf
H
mΘ {Sm(Gly)4(Im)(H2O)}(ClO4)3(s)} = −(3472.7±2.3) kJ mol−1, respectively. 相似文献