Synthesis and Characterization of Zn(II) Complexes of 2-(7-Bromo-2-oxo-5-phenyl-2,3-dihydro-1<Emphasis Type="Italic">H</Emphasis>-1,4-benzodiazepin-1-yl)acetohydrazide and Its Condensation Products with Pyruvic Acid and Isatin

The systems ZnCl₂–2-(7-bromo-2-oxo-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepin-1-yl)acetohydrazide (Hydr)–propan-2-ol, ZnCl₂–Hydr–pyruvic acid (HPv), and Zn(CH₃COO)₂–Hydr–isatin(HIz)–propan-2-ol were studied. Optimal synthesis conditions were determined, and the complexes [Zn(Hydr)₂Cl₂], [Zn(HydrHPv)₂Cl₂], and [Zn(HydrIz)₂] were isolated. The complexes were characterized by elemental analysis, thermogravimetry, IR spectroscopy, and mass spectrometry. The electrical conductivities of the complexes were measured. The local environment of the central atom in the coordination entity was determined by X-ray absorption spectroscopy.     

Three copper(II) complexes constructed from 4-(2-pyridyl)-<Emphasis Type="Italic">1H</Emphasis>-1,2,3-triazole ligands: syntheses,structures, optical,and electrochemical properties

Three Cu(II) complexes constructed from 4-(2-pyridyl)-1H-1,2,3-triazole (L), namely, [CuL₂Cl₂]·H₂O, [CuL₂(CH₃OH)(NO₃)]NO₃ and [CuL₂(H₂O)]SO₄, have been synthesized and characterized. X-ray crystal structure analyses revealed that [CuL₂Cl₂]·H₂O and [CuL₂(CH₃OH)(NO₃)]NO₃ have octahedral geometries, whilst [CuL₂(H₂O)]SO₄ adopts a square-pyramidal coordination geometry. In all three complexes, the Cu(II) atoms are chelated by two L ligands in the basal plane, whilst the apical positions are occupied by Cl^?, NO₃^?, CH₃OH or H₂O. The bandgaps between the HOMO and LUMO were estimated by cyclic voltammetry (CV) and diffuse reflectance spectroscopy (DRS) to be 3.43, 3.12, and 3.74 eV, respectively. Theoretical calculations on each structure gave similar results to the experiments. Frontier molecular orbital analyses showed that the higher electron density on the apical ligand, the lower the bandgap.     

Cu(II)‐promoted cyclization of hydrazonophthalazine to triazolophthalazine; Synthesis and structure diversity of six novel Cu(II)‐triazolophthalazine complexes

A novel route for the synthesis of Cu(II)‐triazolophthalazine complexes using the Cu(II)‐promoted cyclization dehydrogenation reactions of hydrazonophthalazines under reflux was presented. Two hydrazonophthalazines were cyclized to the corresponding triazolophthalazine ligands, 3‐pyridin‐2‐yl‐3,10b‐dihydro‐[1,2,4]triazolo[3,4‐a]phthalazine ( TPP ) and 3‐(3,10b‐dihydro‐[1,2,4]triazolo[3,4‐a]phthalazin‐3‐yl)‐benzoic acid ( TP3COOH ), followed by in situ complexation with Cu(II) yielding six novel Cu(II)‐triazolophthalazine complexes depending on the reaction conditions. The molecular and supramolecular structures of the Cu(II)‐triazolophthalazine complexes were discussed. The metal sites have rectangular pyramidal geometry in the [Cu(TPP)Cl₂]₂; 1 and [Cu(TP3COOEt)Cl₂(H₂O)]₂; 4 dinuclear complexes, distorted square planar in [Cu(TP3COOMe)₂Cl₂]; 3 , [Cu(TP3COOH)₂Cl₂]; 5 and [Cu(TP3COOH)₂Cl₂]·H₂O; 6 and a distorted octahedral in [Cu(TPP)(H₂O)₂(NO₃)₂]; 2 . Hirshfeld analysis showed that the O…H, C…H, Cl…H (except TP3COOH and 2 ), N…H and π‐π stacking interactions are the most important intermolecular contacts. The π‐π stacking interactions are the maximum for TP3COOH and complex 6 with net C…C/C…N contacts of 19.4% and 15.4%, respectively. The orbital–orbital interaction energies of the Cu‐N/Cu‐Cl bonds correlated inversely with the corresponding Cu‐N/Cu‐Cl distances, respectively. The charge transfer processes between Cu(II) and ligand groups were also discussed. The charge densities of the Cu(II) centers are reduced to 0.663–0.995 e due to the interactions with the ligand groups coordinating it.     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.     

Synthesis,spectroscopic characterization and thermal behavior of metal complexes formed with (Z)-2-oxo-2-(2-(2-oxoindolin-3-ylidene)hydrazinyl)-N-phenylacetamide (H2OI)

Complexes of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and U(IV)O₂ with (Z)-2-oxo-2-(2-(2-oxoindolin-3-ylidene)hydrazinyl)-N-phenylacetamide (H₂OI) are reported and have been characterized by various spectroscopic techniques like (IR, UV–Vis, ESR ¹H and ¹³C NMR) as well as magnetic and thermal (TG and DTA) measurements. It is found that the ligand behaves as a neutral tridentate, neutral tetradentate, monoanionic tridentate, monoanionic tridentate and dianionic tridentate. An octahedral geometry for all complexes except [Cu₂(H₂OI)(OAc)₄](H₂O)₂ and [Cu(HOI)Cl](H₂O)₂ which have a square planar geometry. Furthermore, kinetic parameters were determined for each thermal degradation stage of some studied complexes using Coats–Redfern and Horowitz–Metzger methods. The bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated to confirm the geometry of the ligand and the investigated complexes.     

Hydroxo‐bridged Tetranuclear CuII Complexes: {[Cu(bpy)(OH)]4Cl2}Cl2 · 6 H2O and {[Cu(phen)(OH)]4(H2O)2}]Cl4 · 4 H2O

The blue tetranuclear Cu^II complexes {[Cu(bpy)(OH)]₄Cl₂}Cl₂ · 6 H₂O ( 1 ) and {[Cu(phen)(OH)]₄(H₂O)₂}Cl₄ · 4 H₂O ( 2 ) were synthesized and characterized by single crystal X‐ray diffraction. ( 1 ): P 1 (no. 2), a = 9.240(1) Å, b = 10.366(2) Å, c = 12.973(2) Å, α = 85.76(1)°, β = 75.94(1)°, γ = 72.94(1)°, V = 1152.2(4) ų, Z = 1; ( 2 ): P 1 (no. 2), a = 9.770(3) Å, b = 10.118(3) Å, c = 14.258(4) Å, α = 83.72(2)°, β = 70.31(1)°, γ = 70.63(1)°, V = 1252.0(9) ų, Z = 1. The building units are centrosymmetric tetranuclear {[Cu(bpy)(OH)]₄Cl₂}²⁺ and {[Cu(phen)(OH)]₄(H₂O)₂}⁴⁺ complex cations formed by condensation of four elongated square pyramids CuN₂(OH)₂L^ap with the apical ligands L^ap = Cl, H₂O, OH. The resulting [Cu₄(μ₂‐OH)₂(μ₃‐OH)₂] core has the shape of a zigzag band of three Cu₂(OH)₂ squares. The cations exhibit intramolecular and intermolecular π‐π stacking interactions and the latter form 2D layers with the non‐bonded Cl^– anions and H₂O molecules in between (bond lengths: Cu–N = 1.995–2.038 Å; Cu–O = 1.927–1.982 Å; Cu–Cl^ap = 2.563; Cu–O^ap(OH) = 2.334–2.369 Å; Cu–O^ap(H₂O) = 2.256 Å). The Cu…Cu distances of about 2.93 Å do not indicate direct interactions, but the strongly reduced magnetic moment of about 2.74 B.M. corresponds with only two unpaired electrons per formula unit of 1 (1.37 B.M./Cu) and obviously results from intramolecular spin couplings (χ_m(T‐θ) = 0.933 cm³ · mol^–1 · K with θ = –0.7 K).     

Synthesis and spectroscopic studies of 2,5-hexanedione bis(isonicotinylhydrazone) and its first raw transition metal complexes

New VO²⁺, Mn²⁺, Co²⁺, Ni²⁺ Cu²⁺ and Zn²⁺ complexes of 2,5-hexanedione bis(isonicotinylhydrazone) [H₂L] have been synthesized and characterized. The analyses confirmed the formulae: [VO(L)]·H₂O, [Mn₂(H₂L)Cl₂(H₂O)₆]Cl₂, [Co(L)(H₂O)₂]·2H₂O, [Ni(HL)(OAc)]·H₂O, [Cu(L)(H₂O)₂]·2H₂O, [Cu(L)]·2H₂O and [Zn(L)(H₂O)₂]. The formulae of [Ni(HL)(OAc)]·H₂O, [Zn(L)(H₂O)₂] and [Mn₂(H₂L)Cl₂(H₂O)₆]Cl₂, are supported by mass spectra. The molecular modeling of H₂L is drawn and showed intramolecular hydrogen bonding. The ligand releases two protons during reaction from the two amide groups (NHCO) and behaves as a binegative tetradentate (N₂O₂); good evidence comes from the ¹H NMR spectrum of [Zn(L)(H₂O)₂]. The ligand has a buffering range 10–12 and pK's of 4.62, 7.78 and 9.45. The magnetic moments and electronic spectra of all complexes provide a square-planar for [Cu(L)]·2H₂O, square-pyramidal for [VO(L)]·H₂O and octahedral for the rest. The ESR spectra support the mononuclear geometry for [VO(L)]·H₂O and [Cu(L)(H₂O)₂]·2H₂O. The thermal decomposition of the complexes revealed the outer and inner solvents where the end product in most cases is metal oxide.     

Synthesis,physico-chemical investigations and biological studies on Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes with p -amino acetophenone isonicotinoyl hydrazone

Complexes of the type [M(painh)(H₂O)₂X], where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); X = Cl₂ or SO₄; painh = p-amino acetophenone isonicotinoyl hydrazone, have been synthesized and characterized by spectral and other physico-chemical techniques. The synthesized complexes are stable powders, insoluble in common organic solvents such as ethanol, benzene, carbon tetrachloride, chloroform and diethyl ether, and are non-electrolytes. Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA) studies show that the organic ligand decomposes exothermically through various steps. TGA and Infrared (IR) spectral studies indicate the presence of coordinated water in the metal complexes. Magnetic susceptibility measurements and electronic spectra suggest that Mn(II), Co(II), and Ni(II) complexes are paramagnetic with octahedral geometry, whereas Cu(II) complexes have distorted octahedral geometry. The neutral bidentate ligand bonds through >C=O and >C=N–groups in all the complexes. Electron Spin Resonance (ESR) spectra in the solid state show axial symmetry for [Cu(painh)(H₂O)₂(SO₄)] and elongated rhombic symmetry for [Cu(painh)(H₂O)₂Cl₂], suggesting an elongated tetragonally-distorted octahedral structure for both complexes. X-ray powder diffraction parameters for two complexes correspond to tetragonal and orthorhombic crystal lattices. The metal complexes show fair antifungal activity against Rizoctonia sp., Aspergillus sp., Stemphylium sp., and Penicillium sp. and appreciable antibacterial activity against Pseudomonas sp. and Escherichia coli.     

Unusual coordination of a chloride ion to six copper ions: Synthesis and crystal structure of copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

Novel copper(II) complexes, molecular [Cu₆(μ₆-Cl)(μ₃-OH)₂(μ-L)₆Cl₉(H₂O)₃] · 3H₂O (1) and polymeric [Cu(μ-L)(μ-OH)(H₂O)₂]Cl (2) (L = 4-(4-hydroxyphenyl)-1,2,4-triazole), have been prepared and characterized by X-ray structural analysis. Compound 1 appears to be an unusual example of a chloride ion with six equal Cu–Cl distances of 2.8397(3) Å. It has also been characterized by X-ray powder diffraction and magnetic measurements. Both complexes have distorted octahedral configurations of copper ions; the coordination cores are CuN₂Cl₂O₂ or CuN₂Cl₃O (1) and CuN₂O₄ (2).     

Characterization of Cu(II) coordination compounds with 2-(7-bromo-2-oxo-5-phenyl-2,3-dihydro-1<Emphasis Type="Italic">Н</Emphasis>-1,4-benzodiazepin-1-yl)acetohydrazide and a product of its condensation with pyruvic acid

[Cu(HydrHPv)(H₂O)Cl₂] complex has been prepared and characterized by elemental analysis, IR spectroscopy, electrical conductivity, and magnetic susceptibility data. Structure of the coordination sphere and exact parameters of nearest surrounding of Cu²⁺ ions have been determined by X-ray absorption spectroscopy.     

Crystal Structures of [Cu2(bpy)2(H2O)(OH)2(SO4)]·4H2O and [Cu(bpy)(H2O)2]SO4 with bpy = 2, 2′‐Bipyridine

Two sulfato Cu^II complexes [Cu₂(bpy)₂(H₂O)(OH)₂(SO₄)]· 4H₂O ( 1 ) and [Cu(bpy)(H₂O)₂]SO₄ ( 2 ) were synthesized and structurally characterized by single crystal X—ray diffraction. Complex 1 consists of the asymmetric dinuclear [Cu₂(bpy)₂(H₂O)(OH)₂(SO₄)] complex molecules and hydrogen bonded H₂O molecules. Within the dinuclear molecules, the Cu atoms are in square pyramidal geometries, where the equatorial sites are occupied by two N atoms of one bpy ligand and two O atoms of different μ₂—OH groups and the apical position by one aqua ligand or one sulfato group. Through intermolecular O—H···O and C—H···O hydrogen bonds and intermolecular π—π stacking interactions, the dinuclear complex molecules are assembled into layers, between which the hydrogen bonded H₂O molecules are located. The Cu atoms in 2 are octahedrally coordinated by two N atoms of one bpy ligand and four O atoms of two H₂O molecules and two sulfato groups with the sulfato O atoms at the trans positions and are bridged by sulfato groups into ¹[Cu(bpy)(H₂O)₂(SO₄)_2/2] chains. Through the interchain π—π stacking interactions and interchain C—H···O hydrogen bonds, the resulting chains are assembled into bi—chains, which are further interlinked into layers by O—H···O hydrogen bonds between adjacent bichains.     

Structure and Magnetic Properties of Mononuclear Copper(II) Complexes with 2,2‐Bipyrimidine, 2,3‐Bis(2‐pyridyl)pyrazine,and 4‐Terpyridone Based Ligands

Four new complexes of [Cu(bpm)(ox)(H₂O)] ( 1 ), [Cu(tpd)(dca)(H₂O)] ( 2 ), [Cu(bppz)(N₃)₂] ( 3 ), and [Cu(bpm)₂(μ_1,3‐N₃)(N₃)] ( 4 ) (bpm = 2,2′‐bipyrimidine, bppz = 2,3‐bis(2‐pyridyl)pyrazine, tpd = 4‐terpyridone, dca = dicyanamide, ox = oxalate) have been prepared and characterized by X‐ray single‐crystal analysis and variable‐temperature magnetic measurements. Compounds 1–4 are essentially mononuclear Cu(II) complexes. However, in complex 1 , Cu(II) it was found that intermolecular hydrogen bonding through between H₂O and ox formed 1‐D chain structure. In complex 2 it was found that the hydrogen bonding between H₂O and tpd of the next molecule led to for a binuclear Cu(II) complex. In complex 3 , two nitrogen atoms, one of the pyridyl group of bppz and one of N₃^? ligands, are weakly coordinated to neighbor Cu(II) ion thus leading to formation of a 1‐D chain structure. In complex 4 , one nitrogen atom of terminated N₃^? is weakly coordinated to the neighbor Cu(II) site to form a 1‐D polymeric structure. The magnetic susceptibility measurements indicate that complex 1 and 4 exhibit a weak antiferromagnetic interaction whereas a ferromagnetic coupling has been established for complexes 2 and 3 .     

Synthesis,characterization, electrochemical behavior and antioxidant activity of new copper(II) coordination compounds with curcumin derivatives

Five new copper(II) coordination compounds were prepared by template synthesis, using curcumin, 2-hydrazinobenzothiazole and metal salt (copper chloride, bromide, acetate and nitrate) in 1:2:1 and 1:2:2 molar ratio. The complexes were characterized by elemental and thermogravimetric analysis, IR, UV–Vis and mass spectroscopic methods and cyclic voltammetric studies. On the basis of physico-chemical measurements the following formulae have been assigned to the complexes: [Cu(H₂L)(H₂O)₂]Cl₂·H₂O, [CuL]·H₂O, [Cu(H₂L)(H₂O)Br]Br·5H₂O, [Cu₂L(H₂O)₄](NO₃)₂·2H₂O and [Cu₂(H₂L)(NO₃)₄]·H₂O, where H₂L is the hydrazone ligand formed in the reaction conditions. Metal complexes were tested for antioxidant activity by photochemiluminescence and this activity was quantified by comparison with TROLOX®, as standard. The results show that all complexes are more potent antioxidant agents than curcumin.     

Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Four Cu^II and Co^II complexes–[Cu(L₁)Cl₂(H₂O)]3/2H₂O · 1/2EtOH, [Cu(L₁)₂Cl₂]6H₂O, [Co(L₁)Cl₂]3H₂O · EtOH, and [Co₂(L₁)(H₂O)Cl₄]1.5H₂O · EtOH (L₁ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L₁)I₂(H₂O)]6H₂O, [Cu(L₁)₂I₂]6H₂O, [Co(L₁)I(H₂O)₂]I · 2H₂O, and [Co₂(L₁)I₄(H₂O)₃]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for Cu^II or oxidation of Co^II. Oxidation of Co^II to Co^III complexes was only observed on the dissolution of Co^II complexes in d₆-DMSO in air while warming. The isolated solid complexes (Cu^II and Co^II) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, ¹H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML₂ complexes. In binuclear complexes, L is tridentate toward one Co^II and bidentate toward the second Co^II in [Co₂(L₁)Cl₄]2.5H₂O · EtOH and [Co₂(L₁)I₄(H₂O)₃]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around Cu^II and high-spin octahedral and square-pyramidal geometry around Co^II.     

Synthesis and Structure of Copper(II) Nitrate Complexes with 2, 6‐Bis(pyrazolyl)pyridine

Three mononuclear copper(II) complexes of copper nitrate with 2, 6‐bis(pyrazol‐1‐yl)pyridine ( bPzPy ) and 2, 6‐bis(3′,5′‐dimethylpyrazol‐1‐yl)pyridine ( bdmPzPy ), [Cu(bPzPy)(NO₃)₂] ( 1 ), [Cu(bPzPy)(H₂O)(NO₃)₂] ( 2 ) and [Cu(bdmPzPy)(NO₃)₂] ( 3 ) were synthesized by the reaction of copper nitrate with the ligand in ethanol solution. The complexes have been characterized through analytical, spectroscopic and EPR measurements. Single crystal X‐ray structure analysis of complexes 1 and 2 revealed a five‐coordinate copper atom in 1 , whereas 2 contains a six‐coordinate (4+2) Cu^II ion with molecular units acting as supramolecular nodes. These neutral nodes are connected through O–H ··· O(nitrate) hydrogen bonds to give couples of parallel linear strips assembled in 1D‐chains in a zipper‐like motif.     

Synthesis and application of a new copper(II) complex containing oflx and leof

Two new copper(II) complexes of [Cu(Ofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O and [Cu(Levofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O were obtained and their structures were studies. Both ligands and complexes were assayed against gram-positive and gram-negative bacteria by the in vitro doubling dilutions method. The inhibitory effect of the ligands and complexes on the leukemia HL-60 cell line were measured with the MTT assay method and the liver cancer HePG-2 cell line measured by the SRB method. The results indicated that the complexes have stronger inhibitory effect on HL-60 than on HePG-2. The complex [Cu(Levofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O (I) has stronger effect on HL-60 than the complex (Cu(Ofloxacin)(phen)(H₂O)] · (NO₃) · 2H₂O (II). The text was submitted by the authors in English.     

Synthesis and structure of aqua-2′,?-(2,6-pyridindiyldiethylidene) dioxamohydrazide-copper(II) hydrate

In a template synthesis from copper(II) acetate, 2,6-diacetylpyridine, and semioxamazide (NH₂CO CONHNH₂), two copper(II) complexes, [Cu(dapsox)(H₂O)]·H₂O and [Cu(Hdapsox)](H₂O)]ClO₄, (where H₂dapsox = 2′,2?-(2,6-pyridindiyldiethylidene)dioxamohydrazide) were obtained and characterized. The structure of the former complex was determined by a single-crystal X-ray analysis. Cu^II is located in a square pyramidal environment. The polydentate ligand, dapsox²⁻ is coordinated in dianionic form, as an unsymmetrical quadridentate planar system forming one-membered and two-five-membered metal-chelate rings. The fifth coordination site is occupied by a water molecule.     

Molecular modeling,spectral, and biological studies of 4-formylpyridine-4 N-(2-pyridyl) thiosemicarbazone (HFPTS) and its Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Cd(II), Hg(II), and UO2(II) complexes

The present work describes the preparation and characterization of some metal ion complexes derived from 4-formylpyridine-⁴ N-(2-pyridyl)thiosemicarbazone (HFPTS). The complexes have the formula; [Cd(HFPTS)₂H₂O]Cl₂, [CoCl₂(HPTS)]·H₂O, [Cu₂Cl₄(HPTS)]·H₂O, [Fe (HPTS)₂Cl₂]Cl·3H₂O, [Hg(HPTS)Cl₂]·4H₂O, [Mn(HPTS)Cl₂]·5H₂O, [Ni(HPTS)Cl₂]·2H₂O, [UO₂(FPTS)₂(H₂O)]·3H₂O. The complexes were characterized by elemental analysis, spectral (IR, ¹H-NMR and UV–Vis), thermal and magnetic moment measurements. The neutral bidentate coordination mode is major for the most investigated complexes. A mononegative bidentate for UO₂(II), and neutral tridentate for Cu(II). The tetrahedral arrangement is proposed for most investigated complexes. The biological investigation displays the toxic activity of Hg(II) and UO₂(II) complexes, whereas the ligand displays the lowest inhibition activity toward the most investigated microorganisms.     

Complex formation reactions between [Pd(piperazine)(H2O)2]2+ and biorelevant ligands: synthesis and equilibrium constants

[Pd(pip)Cl₂], [Pd(pip)(cbdca)] ? 2H₂O, and [Pd(pip)(malonate)] ? 2H₂O complexes were synthesized and characterized, where pip is piperazine and cbdca is cyclobutanedicarboxylate. The stoichiometry and stability of the complexes formed between [Pd(pip)(H₂O)₂]²⁺ and various biologically relevant ligands (amino acids, peptides, DNA constituents, and dicarboxylic acids) were investigated at 25°C and 0.1 M ionic strength. The stability constant of the complexes formed in solution was determined and the binding centers of the ligands were assigned. The concentration distribution diagrams of the complexes were evaluated.     

Thermal and spectral properties of Cu(II)-5-halogenosalicylates with or without nicotinamide

Summary This paper deals with the preparation and investigation of thermal and spectral properties of the complexes Cu(5-ClSal)₂·2H₂O (I), Cu(5-BrSal)₂·2H₂O (II), Cu(5-ClSal)₂(nia)(H₂O) (III), Cu(5-BrSal)₂(nia)(H₂O) (IV), and Cu(5-ISal)₂(nia)(H₂O) (V) (where Sal=salicylate, and nia=nicotinamide). TG, DTG, DTA, EPR, IR and electronic spectra have been used to study thermal and spectral properties of the complexes. The chemical composition of the complexes, the solid intermediates and the resultant products of thermolysis have been identified by means of elemental analysis and complexometric titration. Schemes of the decomposition of the complexes are suggested. Heating of the compounds first resulted in the release of water molecules. The thermal stability of these complexes can be ordered in the sequence: I <II <IV=V< III. The final product of the thermal decomposition was CuO in all cases. IR data suggested a bidentate coordination of carboxylates to Cu(II) in complexes I-II and bridging ones for complexes III-V.