A study on synthesis and thermal,spectral and biological properties of carboxylato-Mg(II) and carboxylato-Cu(II) complexes with bioactive ligands

Summary Synthesis, elemental (CHN), spectral (FTIR), thermogravimetry (TG), differential thermal analysis (DTA) and complexometric titration have been applied to the investigation of the thermal behavior and structure of the complexes: Mg(ac)₂(mpc)₃·3H₂O(I), Mg(Clac)₂(mpc)₂·3H₂O(II), Mg(Cl₂ac)₂(mpc)₂·3H₂O(III), Mg(Cl₃ac)₂(mpc)₂·3H₂O(IV) and [Cu(ac)₂(mpc)]₂·3H₂O(V) (ac=CH₃COO^-, Clac=ClCH₂COO^-, Cl₂ac=Cl₂CHCOO^-, Cl₃ac=Cl₃CCOO^- and mpc=methyl-3-pyridyl carbamate). Thermal decomposition of these complexes is a multi-stage processes. The composition of the complexes and the solid state intermediate and resultant products of thermolysis had been identified by means of elemental analysis and complexometric titration. The possible scheme of decomposition of the complexes is suggested. Heating the complexes first resulted in a release of water molecules. The TG results show that the loss of the volatile ligand (mpc) occurs in one step for complexes II, IV and V, and in two steps for complexes I and III. The final solid product of thermal decomposition was MgO or CuO. The thermal stability of the complexes can be ordered in the sequence: I=II<IV<III<V. Mpc was coordinated to Mg(II) or Cu(II) through the nitrogen atom of its heterocyclic ring. IR data suggest to a unidentate coordination of carboxylates to magnesium or copper n complexes I-V. The preliminary studies have shown that the complexes do have antimicrobial activities against bacteria, yeasts and/or fungi. The highest antimicrobial activities were manifested by the complex V.     

Thermal and other properties of complexes of Mn(II), Co(II) and Ni(II) with 2,2'-bipyridine and trichloroacetates

Complexes of the general formulae Mn(2-bpy)₂(CCl₃COO)₂, Co(2-bpy)₂(CCl₃COO)₂·H₂O and Ni(2-bpy)₂(CCl₃COO)₂·2H₂O (where: 2-bpy=2,2'-bipyridine) have been prepared and characterized by VIS and IR spectroscopy, conductivity and magnetic measurements. The thermal properties of complexes in the solid state were studied under non-isothermal conditions in air atmosphere. During heating the complexes decompose via different intermediate products to the oxides Mn₃O₄, CoO and NiO. A coupled TG-MS system was used to detection the principal volatile products of thermal decomposition and fragmentation processes of obtained compounds. The principal volatile products of thermal decomposition of complexes are: H₂O⁺, CO₂ ⁺, Cl₂ ⁺ and other. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal behaviour of ZINC(II) carboxylate complexes with methyl-3-pyridyl carbamate

Four new complex compounds were prepared by reaction of zinc carboxylate and methyl-3-pyridyl carbamate. The synthesized complex compounds of the general formula (RCOO)₂ZnL₂ (RCOO^-= HCOO^- (form), CH₃COO^- (ac), CH₃CH₂CH₂COO^- (but), (CH₃)₂CHCOO^- (isobut), L= methyl-3-pyridyl carbamate (mpc)) were characterized by chemical analysis, IR spectroscopy and studied by methods of thermal analysis (TG/DTG, DTA). CH₂O, CO₂, (CH₃)₂CO, (C₃H₇)₂CO were found as volatile products of thermal decomposition. ZnO was found as final product of thermal decomposition of the prepared complexes heated up to 700°C. Mass spectroscopy, X-ray powder diffraction method, IR spectra and chemical analysis were used for the determination of the thermal decomposition products. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis, thermal and other studies of 2,4'-bipyridine-dichloroacetato complexes of Mn(II), Co(II), Ni(II) and Cu(II)

Four new mixed ligand complexes were prepared by the reaction of title metal dichloroacetates and 2,4'-bipyridine. The general formulae of synthesized compounds are M(2,4'-bpy)₂(CCl₂HCOO)₂·nH₂O (where M(II)=Mn, Co, Ni, Cu; 2,4'-bpy=2,4'-bipyridine, n=2 or 4). The complexes have been isolated from aqueous media and characterized by chemical analysis, molar conductance (in MeOH, DMSO and DMF), magnetic, IR and VIS spectral studies. The nature of metal(II)-ligand coordination is discussed. The thermal behaviour of obtained complexes was studied by thermal analysis and TG-MS techniques in air. IR, X-ray powder diffraction and thermoanalytical data were used for the determination of solid intermediate products of the thermal decomposition. The principal volatile products of thermal decomposition of complexes were proved by mass spectroscopy: H₂O⁺, CO⁺ ₂, HCl⁺ ₂, Cl⁺ ₂, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decomposition reactions of metal carboxylato complexes in the solid state. I.: Thermographic and differential thermal studies of metal oxalato,malonato and succinato complexes

Thermal investigation of metal carboxylato complexes of the first transition metals, Mn(II), Fe(II), Fe(III), Co(II), Ni(II) and Cu(II) and non-transition metals like Zn(II) and Cd(II) in the solid state has been carried out under non-isothermal conditions in nitrogen atmosphere by simultaneous TG and DTA. TG and DTA curves inferred that the thermal stability of the complex decreased approximately with the increase of the standard potential of the central metal ion. The thermal parameters like activation energy, E_a, enthalpy change, ΔH, and entropy change, ΔS, corresponding to the dehydration and decomposition of the complexes are determined from TG and DTA curves by standard methods. A linear correlation is found between ΔH and ΔS and E_a and ΔS in dehydration and decomposition processes. DTA curves show an irreversible phase transition for Na₂Mn(mal)₂], Na₂[Cu(mal)₂] and Na₂,[Co(suc)₂] complexes. The residual products in these decomposition processes being a mixture of two oxides, of oxide and carbonate or a mixture of two carbonates.     

Characterization and TG-MS studies of lactato and bipyridine-lactato complexes of Co(II) and Ni(II)

Two lactates and four new mixed ligand complexes with formulae Co(lact)₂·2H₂O, Ni(lact)₂·3H₂O, Co(4-bpy)(lact)₂, Co(2,4'-bpy)₂(lact)₂, Ni(4-bpy)(lact)₂·2H₂O and Ni(2,4'-bpy)₂(lact)₂ (where 4-bpy=4,4'-bipyridine, 2,4'-bpy=2,4'-bipyridine, lact=CH₃CH(OH)COO^-) were isolated and investigated. The thermal behaviour of compounds was studied by thermal analysis (TG, DTG, DTA). In the case of hydrated complexes thermal decomposition starts with the release of water molecules. The compounds decompose at high temperature to metal(II) oxides in air. A coupled TG-MS system was used to analyse the principal volatile products of thermolysis and fragmentation processes of obtained complexes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermoanalytical Study of Cu-Mg-Zn Ferrites

Homogeneous solid solution oxalates of Fe²⁺, Cu²⁺, Mg²⁺ and Zn²⁺ metals were prepared by co-precipitation from respective metal acetate solutions with oxalic acid solution. The thermogravimetric (TG) analysis of co-precipitated oxalate complexes with general formula Mg_xCu_(0.50-x)Zn_0.50Fe₂(C₂O₄)₃·nH₂O (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50) were carried out by manual method in static air atmosphere. The total mass loss % and stepwise mass loss % values are in good agreement with theoretically calculated mass loss % values. The thermal decomposition of oxalate complexes occur at relatively lower temperatures (561 to 698 K). The lowering of decomposition temperatures may be attributed to earlier initiation of Fe²⁺ oxalate in oxalate complexes. At temperatures between 598–698 K the thermal decomposition of Cu-Mg-Zn-Fe solid solution oxalate complexes leads to formation of ferrites of spinel structure. After tampering at 873 and 1273 K, homogeneous ferrites arise, which is revealed from XRD studies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Decomposition of Mg(II) Complexes with Ronicol

The thermal decomposition of the complexes Mg(Clac)₂ (ron)₂ ×3H₂ O(I), Mg(Cl₂ ac)₂ (ron)₂ ×3H₂ O(II) and Mg(Cl₃ ac)₂ (ron)₂ ×3H₂ O(III), where Clac =ClCH₂ COO^- , Cl ₂ ac =Cl₂ CHCOO^- , Cl ₃ ac =Cl₃ CCOO^- and ron =3-pyridylcarbinol (ronicol) had been investigated in air atmosphere in temperature range 20–1000°C by means of TG and DTA. The composition of the complexes and the solid state intermediate and resultant products of thermolysis had been identified by means of elemental analysis and complexometric titration. The possible scheme of destruction of the complexes is suggested. The final product of the thermal decomposition was MgO. The thermal stability of the complexes can be ordered in the sequence: I<III<II. IR data suggest that ronicol was coordinated to Mg(II) through the nitrogen atom of its heterocyclic ring. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal,Spectral and Antimicrobial Properties of New Zinc(II) Isobutyrate Compounds: Part I. Papaverine,Phenazone

Zinc carboxylate complexes with N-donor ligands exhibit antimicrobial and antifungal effects. The preparation and thermal properties of complex compounds Zn(isobut)₂ and Zn(isobut)₂L(isobut=(CH₃)₂CHCOO^–, L=papaverine — pap, phenazone — phen) are described in this paper. The newly synthesized compounds were characterized by elemental analysis, IR spectroscopy and TG/DTG, DTA methods.During the thermal treatment it was found that the release of organicligands (pap, phen) was followed by pyrolysis of zinc(II) isobutyrate. (C₃H₇)₂CO and CO₂ were found as gaseous products and zinc oxide as the final product of thermal decomposition. Gaseous and solid products of thermal decomposition were confirmed by chemical analysis, IR spectra and X-ray powder diffraction.This revised version was published online in November 2005 with corrections to the Cover Date.     

Complexes of Mn(II), Co(II), Ni(II) and Cu(II) with 4,4'-bipyridine and dichloroacetates

New mixed-ligand complexes with empirical formulae M(4-bpy)L₂·1.5H₂O (M(II)=Mn, Co), Ni(4-bpy)₂L₂ and Cu(4-bpy) L₂·H₂O (where: 4-bpy=4,4'-bipyridine, L=CC L2HCOO^-) have been isolated in pure state. The complexes have been characterized by elemental analysis, ir spectroscopy, conductivity (in methanol, dimethylformamide and dimethylsulfoxide solutions) and magnetic and x-ray diffraction measurements. The Mn(II) and Co(II) complexes are isostructural. The way of metal-ligand coordinations discussed. the ir spectra suggest that the carboxylate groups are bonded with metal(II) in the same way (Ni, Cu) or in different way (Mn, Co). The solubility in water is in the order of 19.40·10^-3÷1.88·10^-3ł mol dm^-3ł. During heating the hydrate complexes lose all water in one step. The anhydrous complexes decompose to oxides via several intermediate compounds. A coupled TG-MS system was used to analyse the principal volatile products of obtained complexes. The principal volatile products of thermal decomposition of complexes in air are: H₂O₂ ⁺, CO₂ ⁺, HCl⁺, Cl₂ ⁺, NO⁺ and other. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal analysis of apatite structure

Two types of thermal effects, caused by substitutions (Ca²⁺↔ Na⁺, ↔ CO₃ ^2-, SO₄ ^2-, OH^-↔ F^-) in synthetic precipitated apatites as well as by sorption of Cd²⁺, Zn²⁺, and Cr³⁺ ions from the solutions were studied by TG/DTA, XRD and FTIR analysis. The temperatures of exothermic effect at 330-340°C and of decomposition of carbonate and sulfate apatites at 650-950°C were shown to depend on the substitutions in the apatite structure. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal investigations of cefadroxil complexes with transition metals

The cefadroxil (Cef) complexes with transition divalent metals of the formula MCef·nH₂O (where n=2 for M=Cu²⁺, Ni²⁺, Zn²⁺ and n=3 for Co²⁺) and CdCef_1.5·4H₂O were prepared and characterized by elemental and infrared spectra. The thermal analysis of the investigated complexes in air atmosphere was carried out by means of simultaneous TG-DSC technique. During heating in air they lose bound water molecules and then decompose to oxides: Co₃O₄, NiO, CuO, ZnO and CdO. The CdCef_1.5·4H₂O complex forms probably an intermediate product Cd₂OSO₄. The combined TG-FTIR technique was employed to study of decomposition pathway of the investigated complexes. The first mass loss step is the water loss of the complexes. Next, decomposition of cefadroxil ligand occurs with evolution of CO₂ and NH₃. At slightly higher temperature COS is observed according to decomposition of cephem ring. Additionally, as decomposition gaseous products: HCN, HNCO (HOCN), H₂CNH, CO, SO₂, hydrocarbons and carbonyl compounds were observed. The formation of metal sulfates is postulated as solid intermediate product of decomposition in the argon atmosphere. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermoanalytical investigation and biological properties of zinc(II) 4-chloro- and 5-chlorosalicylates with N-donor ligands

New zinc(II) 4- and 5-chlorosalicylate complexes of general formula [Zn(X-sal)₂(L) _n (H₂O) _x ] (where X-sal?=?4-Clsalicylate, 5-Clsalicylate; L?=?N,N-diethylnicotinamide, isonicotinamide, theophylline; n?=?1, 2; x?=?0, 1, 2, 4) were prepared. The complexes were determined by elemental analysis and characterised by infrared spectroscopy. The thermal behaviour of the complexes was studied by simultaneous TG, DTG and DTA methods under dynamic air conditions. The thermal decomposition is a multi-step process. In the first step of the thermal decomposition, water is released in hydrated compounds. The anhydrous compounds start to decompose by the release of organic ligand, followed by chlorosalicylic acid, chlorophenol and carbon monoxide. The final solid product of the thermal decomposition is zinc oxide. The volatile products of the thermal decomposition were determined by mass spectrometry. The antimicrobial activities of the complexes were evaluated against selected pathogen and probiotic bacteria, yeasts and fungi strains. Bioactivities of the tested compounds are different against bacteria, yeasts and filamentous fungi. It was found that bacteria were more sensitive to the studied zinc(II) complex compounds than yeasts or filamentous fungi.     

Thermal behaviour of the homopolynuclear glyoxylate complex combinations with Cu(II) and Cr(III)

Homopolynuclear complexes of Cu(II) respectively Cr(III) with the glyoxylate dianion, C₂H₂O₄ ^2-, have been studied in non-isothermal regime in air and nitrogen. The results of the non-isothermal analysis performed for the synthesised complexes, Cu(C₂H₂O₄)·0.5H₂O, respectively [Cr₂(OH)₂(C₂H₂O₄)₂(OH₂)₄]·2H₂O, correlated with the results of the IR and TG analysis of the compounds obtained by thermal treatment from the initial complexes and the results of the GLC and XR analysis have led to the establishment of the thermal decomposition mechanisms for the two studied complexes. The decomposition mechanisms confirm the stoichiometric and structural formulae proposed for the two synthesised homopolynuclear complexes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,thermal, spectral and biological properties of zinc(II) 4-hydroxybenzoate complexes

New zinc(II) 4-hydroxybenzoate complex compounds with general formula [Zn(4-OHbenz)₂L_n]·xH₂O, where 4-OHbenz = 4-hydroxybenzoate; L = isonicotinamide, N-methylnicotinamide, N,N-diethylnicotinamide, thiourea, urea, phenazone, theophylline, methyl-3-pyridylcarbamate; n = 2, 3; x = 0–3, 5, were synthesized and characterised by elemental analysis, thermal analysis and IR spectroscopy. The thermal behaviour of the prepared compounds was studied by TG/DTG and DTA methods in argon atmosphere. The thermal decomposition of hydrated compounds started with dehydration. During the thermal decomposition, organic ligand, carbon monoxide, carbon dioxide and phenol were evolved. The final solid product of the thermal decomposition was zinc or zinc oxide. The volatile gaseous product, solid intermediate products and the final product of thermal decomposition were identified by IR spectroscopy, mass spectrometry, qualitative chemical analyses and X-ray powder diffraction method. The antimicrobial activity of zinc(II) carboxylate compounds was tested against various strains of bacteria, yeasts and filamentous fungi (S. aureus, E. coli, C. parapsilosis, R. oryzae, A. alternata, M. gypseum). The presence of zinc in complexes led to the increase in their antimicrobial activity in comparison with free 4-hydroxybenzoic acid.     

Kinetic Analysis of the Thermal Decomposition of Dialkyldithiocarbamates Chelates of Indium(III)

The kinetics of thermal decomposition of solid In(S₂CNR₂)₃ complexes, (R=CH₃, C₂H₅, n-C₃H₇,i-C₃H₇, n-C₄H₉ and i-C₄H₉), has been studied using isothermal and non-isothermal thermogravimetry. Superimposed TG/DTG/DSC curves show that thermal decomposition reactions occur in the liquid phase, except for the In(S₂CNMe₂)₃ and In(S₂CNPrⁱ ₂)₃ compounds. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structural studies of 4-benzamido-1-o-aminoacetophenone-3-thiosemicarbazone complexes

Summary Complexes of Cu^II, Ni^II, Co^II, Zn^II, Cd^II and Hg^II with 4-benzamido-1-o-aminoacetophenone-3-thiosemicarbazone (H₂BATS) are reported and have been characterized by elemental analyses, molar conductivities, magnetic moments, spectral (visible, i.r.) and thermal (d.t.a., t.g., d.t.g.) measurements. I.r. spectra show that H₂BATS behaves as a dianionic, monoanionic or neutral tetradentate ligand or as a monoanionic tridentate ligand. [Cu₂(H₂BATS)Cl₂]·2H₂O and [Cu₂(H₂BATS)Ac₂]·2H₂O complexes are diamagnetic while [Co(HBATS)OH]·2H₂O and [Ni(HBATS)OH]·2H₂O are octahedral. All the complexes are non-electrolytes. Generally, the solid metal acetate complexes have a unique decomposition exotherm profile which can be used as a rapid and sensitive tool for the detection of acetate-containing complexes.     

Heteroleptic tri-<Emphasis Type="Italic">tert</Emphasis>-butoxysilanethiolate complexes of manganese(II)

The thermal behavior of Mn(II) silanethiolate series [Mn(SR)₂L(MeOH)_n], where R=SSi(OBut)₃, L=heterocyclic nitrogen base and n=0, 1 or 2 has been comparatively investigated using differential scanning calorimetry (DSC), thermogravimetry (TG) and TG-infrared spectoscopy (IR) techniques. The TG curves indicate the differences in the thermal decomposition due to presence of distinct N-donor ligands and labile MeOH molecules coordinated to the central atom. The first step on the TG curves (60–110°C) corresponds to the elimination of alcohol from respective complexes. The main step (150–350°C) can be assigned to the decomposition of the complexes yielding Mn₃O₄ and silica as the main final products, identified by X-ray diffraction patterns.     

Thermal study of zinc(II) salicylate complex compounds with bioactive ligands

Five new complex compounds of general formula Zn(Hsal)_2·L₂·nH₂O (where Hsal=OHC₆H₄COO^-, L=thiourea (tu), nicotinamide (nam), caffeine (caf), theobromine (tbr), n=2-4), were prepared and characterized by chemical analysis, IR spectroscopy and studied by methods of thermal analysis (TG/DTG, DTA). It was found that the thermal decomposition of hydrated compounds starts with the release of water molecules. During the thermal decomposition of anhydrous compounds the release of organic ligands take place followed by the decomposition of salicylate anion. Zinc oxide was found as the final product of the thermal decomposition heated up to 800°C. RTG powder diffraction method, IR spectra and chemical analysis were used for the determination of products of the thermal decomposition. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis,molecular and crystal structure,magnetic properties,luminescence, and solid-phase thermolysis of binuclear Ln(III) pivalates with 2,2′-dipyridyl and 1,10-phenanthroline molecules

Methods of synthesis of binuclear pivalate complexes L₂Ln₂(μ-O,η²-OOCCMe₃)₂(μ₂-O,O′-OOCCMe₃)₂(η²-OOCCMe₃)₂, where Ln = Sm, Eu, Gd, or Er and L = 2,2′-dipyridyl (Bipy) or 1,10-phenanthroline (Phen), from the corresponding binuclear complexes Ln₂(μ₂-OOCCMe₃)₄(OOCCMe₃)₂(HOOCCMe₃)₆ · HOOCCMe₃(I–IV), as well as of coordination polymers {Ln(OOCCMe₃)₃} _n , were suggested. The compounds were characterized by X-ray crystallography and X-ray powder diffraction and their magnetic properties, solid-phase thermolysis, and the phase composition of solid decomposition products were studied. The structures of the metal carboxylate core and surrounding ligands were shown to have an effect on the thermal stability of the complexes. The luminescence properties of the Eu(III) complexes were analyzed.