Thermal,spectral and magnetic properties of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II)

The complexes of 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) have been synthesized as hydrated polycrystalline solids and characterized by elemental analysis, IR, FIR and electronic spectroscopy, magnetic studies and X-ray diffraction measurements. They possess colours typical of the M(II) ions: Cu-blue, Ni-green, Co-pink. The carboxylate groups bind as monodentate or a symmetrical, bidentate chelating or bridging ligands. The thermal stabilities were determined in air. When heated they dehydrate to form anhydrous salts which are decomposed to the oxides of respective metals. The magnetic susceptibilities of the complexes were measured over the range 77-300 K and the magnetic moments were calculated. The results reveal the complexes of Ni(II) and Co(II) to be high-spin complexes and that of Cu(II) to form dimer.     

Thermal and spectral properties of halogenosalicylato-Cu(II) complexes

The paper presents the applicability of oxyreactive thermal analysis (OTA) for the investigation of different kinds of resins both natural (recent and fossil) and synthetic. For comparative reasons and a more precise interpretation, along with OTA infrared spectroscopy was used as a method commonly applied for the investigation of fossil resins. The results obtained prove that the OTA method may be very useful for diversification of different kinds of resins. The parameter most valuable for the preliminary characteristics of resins and the evaluation of their transformation was found to be the mass loss recorded on TG curves in three definite temperature ranges. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal properties of zinc(II) chloroacetate and its complexes with nicotinamide and caffeine

Thermal decompositions of zinc(II) chloroacetate and its complexes with nicotinamide and caffeine were studied by means of TG/DTG, DTA, IR and mass spectroscopy. Thermal analysis showed that presence of the halogen significantly influenced the thermal decomposition. Decompositions may be characterized as two step reactions (release of nicotinamide or caffeine followed by pyrolysis of the carboxylate anion). Zinc chloride, CO, CO₂, CH₂O, ClCH₂CHO were found in gaseous products of the thermal decomposition.     

钴(Ⅱ)和铜(Ⅱ)膦酸配位聚合物的热、磁性能

3-氨基-1-羟基丙叉-1,1-二膦酸与钴或铜离子的水热反应得到新的配聚物Co2(NH3CH2CH2C(OH)(PO3)(PO3H))2·2H2O (1) 和Cu3{[NH3CH2CH2C(OH)(PO3)2](H2O)2} (2).研究了两个配合物的热稳定性,采用变温磁化率研究了在5-300 K范围内的磁性能. 结果表明:在配合物1中,钴离子间存在着弱的反铁磁偶合作用,理论拟合值为J=-2.1 cm-1,g=2.18;配合物2中,铜离子间的磁作用较复杂.     

Thermal and spectral studies of 5-(phenylazo)-2-thiohydantoin and 5-(2- hydroxyphenylazo)-2-thiohydantoin complexes of cobalt(II), nickel(II) and copper(II)

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=Ni^ll and Cu^ll} 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.     

Synthesis,crystal structure,Hirshfeld surfaces,and spectral properties of Cu(II) and Co(II) complexes with 3-phenoxymethyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole

A new asymmetrical substituted triazole, 3-phenoxymethyl-4-phenyl-5-(2-pyridyl)-1,2,4-triazole (L) and its complexes, cis-[Cu₂ L ₂Cl₄]·2CH₃CN (1) and trans-[CoL ₂Cl₂]·2H₂O·2CH₃CN (2), have been synthesized and characterized by IR, single-crystal X-ray diffraction, thermogravimetric analyses and Hirshfeld surfaces. In the structure, two L are mainly stabilized by an intermolecular C–H?N hydrogen bond. In 1 (or 2), each L involves a doubly-bidentate (or chelating bidentate) coordination mode through one pyridine and two nitrogens (or one) of triazole, respectively. Complex 1 has a distorted trigonal bipyramidal [CuN₃Cl₂] core with two cis Cl^? while 2 shows a distorted octahedron [CoN₄Cl₂] with two trans Cl^?. We also prepared molecular Hirshfeld surface and fingerprint plot for L, 1 and 2, which revealed the influence of different metals on coordinate of L.     

Thermal,spectral and biological properties of Zn(II) complex compounds with phenazone

The thermal decomposition of the complexes Zn(form)₂⋅2phen (I), Zn(ac)₂⋅2phen (II), Zn(prop)₂⋅2phen (III), Zn(but)₂⋅2phen (IV), where phen=phenazone, form=formiate, ac=acetate, prop=propionate, but=butyrate has been studied in air by TG/DTG and DTA methods. The possible mechanism of the thermal decomposition was proposed. The final product of thermal decomposition was ZnO. IR data show unidentate coordination of carboxylate group to Zn(II) ion. The complexes were tested against various strains of microorganisms and their efficiency decrease in the sequence yeasts >bacteria>filamentous fungi.     

bis(nicotinamide) and bis(N,N-diethyl nicotinamide) p-hydroxybenzoate complexes of Ni(II), Cu(II) AND Zn(II)

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.     

Syntheses,crystal structures,and spectral properties of Mn(II) and Co(II) complexes with 3-(p-chlorophenyl)- 4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole

Two new complexes, trans-[MnL₂(NCS)₂] (1) and trans-[CoL₂(H₂O)(EtOH)](ClO₄)₂?·?H₂O (2) with asymmetrical triaryltriazole ligands [L?=?3-(p-chlorophenyl)-4-(p-methylphenyl)-5-(2-pyridyl)-1,2,4-triazole], have been synthesized and characterized by elemental analysis, FT-IR, ESI-MS, and single-crystal X-ray diffraction. In the complexes each L adopts a chelating bidentate mode via the nitrogen of pyridyl and triazole. Both complexes have a similar distorted octahedral core with two NCS^? ions in the trans position in 1, while one H₂O and one EtOH are present in the axial sites in 2.     

Thermal behavior of Cu(II)-, Cd(II)-, and Hg(II)-exchanged montmorillonite complexedwith cysteine

The thermal behavior of montmorillonite and organically modified montmorillonite, both treated with heavy metal cations [Cu(II), Cd(II) and Hg(II)], was characterized via thermal analyses (TG, DTG and DTA) combined with evolved species gas mass spectrometry (MS-EGA), and X-ray diffraction at in situ controlled temperature (HTXRD). The reactions involving Cu(II)- and Cd(II)-montmorillonite samples are mostly related to H₂O and OH loss, unlike Hg(II)-montmorillonite, where effects associated to Hg(II) loss are also present. Finally reactions related to dehydration, dehydroxylation and to organic matter decomposition can be observed in montmorillonite samples treated with cysteine.     

Thermal decomposition of Mn(II) complex of nicotinamide

The complex Mn(Nica)₂Cl₂ (Nica=nicotinamide) was prepared, and its decomposition was studied by means of TG and DSC. The IR spectra of the products of thermal decomposition were examined at every stage. Kinetic analysis of the first stage of thermal decomposition was performed via the TG-DTG curves, and the kinetic parameters were obtained from analysis of the TG-DTG curves with integral and differential methods. The most probable kinetic function was suggested from a comparison of the kinetic parameters. Mathematical expressions were derived for the kinetic compensation effect.

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Zusammenfassung Der Komplex Mn(Nica)₂Cl₂ (Nica steht für Nikotinamid) wurde hergestellt und seine Zersetzung mittels TG und DSC untersucht. Die thermisch zersetzten Substanzen jedes Schrittes wurden mittels IR-Spektren untersucht. Anhand der TG-DTG-Kurven erstellte man eine kinetische Analyse des ersten Schrittes der thermischen Zersetzung, die kinetischen Parameter wurden aus den TG-DTG-Kurven unter Einsatz von Integrations- und Differentialmethoden ermittelt. Durch Vergleich der kinetischen Parameter wurde die wahrscheinlichste kinetische Funktion vorgeschlagen. Mathematische Ausdrücke für den kinetischen Kompensationseffekt wurden erhalten.

     

Thermal, spectral and magnetic characterization of Co(II), Ni(II) AND Cu(II) 4-chloro-2-nitrobenzoates

Physico-chemical properties of 4-chloro-2-nitrobenzoates of Co(II), Ni(II), and Cu(II) were studied. The complexes were obtained as mono- and trihydrates with a metal ion to ligand ratio of 1:2. All analysed 4-chloro-2-nitrobenzoates are polycrystalline compounds with colours depending on the central ions: pink for Co(II), green for Ni(II), and blue for Cu(II) complexes. Their thermal decomposition was studied only in the range of 293–523 K, because it was found that on heating in air above 523 K 4-chloro-2-nitrobenzoates decompose explosively. Hydrated complexes lose crystallization water molecules in one step and anhydrous compounds are formed. The final products of their decomposition are the oxides of the respective transition metals. From the results it appears that during dehydration process no transformation of nitro group to nitrite takes place. The solubilities of analysed complexes in water at 293 K are of the order of 10^–4–10^–2 mol dm^–3. The magnetic moment values of Co²⁺, Ni²⁺ and Cu²⁺ ions in 4-chloro-2-nitrobenzoates experimentally determined at 76–303 K change from 3.89 to 4.82 μ_B for Co(II) complex, from 2.25 to 2.98 μ_B for Ni(II) 4-chloro-2-nitrobenzoate, and from 0.27 to 1.44 μ_B for Cu(II) complex. 4-chloro-2-nitrobenzoates of Co(II), and Ni(II) follow the Curie–Weiss law. Complex of Cu(II) forms dimer.     

Thermal, FTIR and Raman spectral analysis of Cu(II)-doped lead iodate crystals

The 0.04 M copper-doped lead iodate crystals grown in silica gel were characterized by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy and thermo analytical techniques (TG, DTA, DTG and DSC). Raman and FTIR spectrum clearly indicate that the functional groups of undoped lead iodate were not altered by the addition of the dopant. Thermal analysis suggests that the thermal stability of lead iodate crystals decreases due to copper doping.     

Thermal, spectral and magnetic behaviour of 2,3,4-trimethoxybenzoates of Mn(II), Co(II), Ni(II) AND Cu(II)

Four new complexes of 2,3,4-trimethoxybenzoic acid anion with manganese(II), cobalt(II), nickel(II) and copper(II) cations were synthesized, analysed and characterized by standard chemical and physical methods. 2,3,4-Trimethoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) are polycrystalline compounds with colours typical for M(II) ions. The carboxylate group in the anhydrous complexes of Mn(II), Co(II) and Ni(II) is monodentate and in that of Cu(II) monohydrate is bidentate bridging one. The anhydrous complexes of Mn(II), Co(II) and Ni(II) heated in air to 1273 K are stable up to 505–517 K. Next in the range of 505–1205 K they decompose to the following oxides: Mn₃O₄, CoO, NiO. The complex of Cu(II) is stable up to 390 K, and next in the range of 390–443 K it loses one molecule of water. The final product of its decomposition is CuO. The solubility in water at 293 K is of the order of 10^–3 mol dm^–3 for the Mn(II) complex and 10^–4 mol dm^–3 for Co(II), Ni(II) and Cu(II) complexes. The magnetic moment values of Mn²⁺, Co²⁺, Ni²⁺ and Cu²⁺ ions in 2,3,4-trimethoxybenzoates experimentally determined in the range of 77–300 K change from 5.64–6.57 μB (for Mn²⁺), 4.73–5.17 μB (for Co²⁺), 3.26–3.35 μB (for Ni²⁺) and 0.27–1.42 μB (for Cu²⁺). 2,3,4-Trimethoxybenzoates of Mn(II), Co(II) and Ni(II) follow the Curie–Weiss law, whereas that of Cu(II) forms a dimer.     

Thermal, spectral, magnetic and antimicrobial behaviour of new Ni(II), Cu(II) and Zn(II) complexes with a hexaazamacrocyclic ligand

New species of type MLCl₂·nH₂O (M:Ni, n = 6; M:Cu, n = 1.5 and M:Zn, n = 1; L: 1,8-bis(3′-ketopyridil)-1,3,6,8,10,13-hexaazacyclotetradecane, ligand resulted by 1,2-diaminoethane, nicotinamide and formaldehyde template condensation) were synthesised. The compounds were characterised by chemical analysis, ESI–MS, IR, NMR, UV–Vis-NIR and EPR spectroscopy as well as magnetic data at room temperature. The modifications in the IR and NMR spectra are in accordance with the condensation process. Electronic spectra indicate that Ni(II) adopts an octahedral stereochemistry while the surrounding of Cu(II) is square-pyramidal. The proposed stereochemistry was furthermore confirmed by magnetic moments and EPR spectrum at room temperature. The water is eliminated in one or two steps, respectively, while the oxidative degradation of the ligand and chloride decomposition occur in two steps. The final residues consist of the most stable metallic oxides as X-ray powder diffraction indicates. The newly synthesised compounds were evaluated for their antimicrobial effect against different bacterial and fungal strains.     

Thermal,spectroscopic and structural studies of zinc(II) complex with nicotinamide

The zinc(II) complex with nicotinamide (ncam) was prepared and investigated by single-crystal X-ray diffraction, infrared spectrum (FTIR), conductivity and thermal analysis techniques. The formula of complex is [Zn(ncam)₂(H₂O)₄](NO₃)₂·2H₂O. The nicotinamide molecule has three following donor sites: pyridine ring nitrogen, aminonitrogen and carbonyl group oxygen. In this monomeric complex, the Zn(II) ion is six-coordinated by two pyridine ring N atoms and four water O atoms in a slightly distorted octahedral arrangement. In the crystal structure, intermolecular O-H…O and N-H…O hydrogen bonds link the molecules to form a supramolecular structure. The complex is stable up to 323 and above 360 K it dehydrates in one step losing six water molecules. The dehydration proceeds in the range of 360–438 K, and its enthalpy value is equal to 62.6±1.5 kJ mol⁻¹.     

Insight on thermal,spectral, magnetic and biological behaviour of new Ni(II), Cu(II) and Zn(II) complexes with a pentaazamacrocyclic ligand derived from nicotinamide

New species of type [MLCl₂]·nH₂O (M:Ni, n = 0; M:Cu, n = 1 and M:Zn, n = 0; L: 1,3,5,8,11-pentaazacyclotridecane-3-yl-(pyrid-3-yl)-methanone resulted by N,N’-bis(2-aminoethyl)ethane-1,2-diamine, nicotinamide and formaldehyde) were synthesised by one-pot condensation. Chemical analysis, ESI–MS, IR, ¹H NMR, ¹³C NMR, UV–Vis–NIR, EPR spectroscopy as well as magnetic data at room temperature were used in order to characterise the compounds. The data provided by IR, ESI–MS and NMR spectra are consistent with the macrocycle formation. Electronic spectra indicate that both Ni(II) and Cu(II) adopt an octahedral stereochemistry data furthermore confirmed by magnetic moments and EPR spectrum at room temperature. The electrochemical behaviour of the compounds was investigated by cyclic voltammetry. Processes as water and chloride elimination as well as oxidative degradation of the macrocyclic ligand were observed by simultaneously TG–DTA measurements. The final residue as the most stable metallic oxide was identified by X-ray powder diffraction. The compound [CuLCl₂]·H₂O (2) exhibits fungicidal and anti-biofilm activity on Candida albicans strains. The complexes exhibit a low cytotoxicity on HEp 2 cells, except for Cu(II) species that induce the cellular cycle arrest in the G2/M phase.     

Multiwavelength spectral correction for the simultaneous determination of Cu(II), Fe(II), and Zn(II) with 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid

A new analytical method is described for the simultaneous determination of various components by multiwavelength spectrophotometry. Because of the influence of the free ligand and various complexes on spectrophotometric absorption, the spectral correction principle was used to establish the calculation matrix formula. The 3 sensitive reactions of Cu(II), Fe(II), and Zn(II), with 1-(5-bromo-2-pyridylazo)-2-naphthol-6-sulfonic acid were studied at pH 10.5. In analyses of fortified samples, the recoveries of Fe, Zn, and Cu were between 93.0 and 103%, 87.0 and 108%, and 92.5 and 108%, respectively; the relative standard deviations for 5 determinations of Fe, Zn, and Cu in unfortified ore were 3.6, 5.8, and 4.5%, respectively.