Syntheses,crystal structures,and physical properties of dinuclear copper(I) and tetranuclear mixed-valence copper(I,II) complexes with hydroxylated bipyridyl-like ligands

Four copper complexes with hydroxylated bipyridyl-like ligands, namely [Cu(2)(ophen)(2)] (1), [Cu(4)(ophen)(4)(tp)] (2), [Cu(4)(obpy)(4)(tp)] (3), and [Cu(4)(obpy)(4)(dpdc)].2H(2)O (4), (Hophen=2-hydroxy-1,10-phenanthroline, Hobpy=6-hydroxy-2,2'-bipyridine, tp=terephthalate, dpdc=diphenyl-4,4'-dicarboxylate) have been synthesized hydrothermally. X-ray single-crystal structural analyses of these complexes reveal that 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy) ligands are hydroxylated into ophen or obpy during the reaction, which provides structural evidence for the long-time argued Gillard mechanism. The dinuclear copper(I) complex 1 has three supramolecular isomers in the solid state, in which short copper-copper distances (2.66-2.68 A) indicate weak metal-metal bonding interactions. Each of the mixed-valence copper(i,ii) complexes 2-4 consists of a pair of [Cu(2)(ophen)(2)](+) or [Cu(2)(obpy)(2)](+) fragments bridged by a dicarboxylate ligand into a neutral tetranuclear dumbbell structure. Dinuclear 1 is an intermediate in the formation of 2 and can be converted into 2 in the presence of additional copper(II) salt and tp ligands under hydrothermal conditions. In addition to the ophen-centered pi-->pi* excited-state emission, 1 shows strong emissions at ambient temperature, which may be tentatively assigned as an admixture of copper-centered d-->s,p and MLCT excited states.     

Oligonuclear 3d-4f complexes as tectons in designing supramolecular solid-state architectures: impact of the nature of linkers on the structural diversity

Heteronuclear cationic complexes, [LCuLn]3+ and [(LCu)2Ln]3+, were employed as nodes in designing high-nuclearity complexes and coordination polymers with a rich variety of network topologies (L is the dianion of the Schiff base resulting from the 2:1 condensation of 3-methoxysalycilaldehyde with 1,3-propanediamine). Two families of linkers have been chosen: the first consists of exo-dentate ligands bearing nitrogen-donor atoms (bipyridine (bipy), dicyanamido (dca)), whereas the second consists of exo-dentate ligands with oxygen-donor atoms (anions derived from the acetylenedicarboxylic (H2acdca), fumaric (H2fum), trimesic (H3trim), and oxalic (H2ox) acids). The ligands belonging to the first family prefer copper(II) ions, whereas the ligands from the second family interact preferentially with oxophilic rare-earth cations. The following complexes have been obtained and crystallographically characterized: [LCu(II)(OH2)Gd(III)(NO3)3] (1), [{LCu(II)Gd(III)(NO3)3}2(mu-4,4'-bipy)] (2), 1infinity[LCu(II)Gd(III)(acdca)(1.5)(H2O)2].13H2O (3), 2infinity[LCu(II)Gd(III)(fum)(1.5)(H2O)2].4H2O.C2H5OH (4), 1infinity[LCu(II)Sm(III)(H2O)(Hfum)(fum)] (5), 1infinity[LCu(II)Er(III)(H2O)2(fum)]NO3.3H2O (6), 2infinity[LCu(II)Sm(III)(fum)(1.5)(H2O)2].4H2O.C2H5OH (7), [{(LCu(II))2Sm(III)}2fum2](OH)2 (8), 1infinity[LCu(II)Gd(III)(trim)(H2O)2].H2O (9), 2infinity[{(LCu(II))2Pr(III)}(C2O4)(0.5)(dca)]dca.2H2O (10), [LCu(II)Gd(III)(ox)(H2O)3][Cr(III)(2,2'-bipy)(ox)2].9H2O (11), and [LCuGd(H2O)4{Cr(CN)6}].3H2O (12). Compound 1 is representative of the whole family of binuclear Cu(II)-Ln(III) complexes which have been used as precursors in constructing heteropolymetallic complexes. The rich variety of the resulting structures is due to several factors: 1) the nature of the donor atoms of the linkers, 2) the preference of the copper(II) ion for nitrogen atoms, 3) the oxophilicity of the lanthanides, 4) the degree of deprotonation of the polycarboxylic acids, 5) the various connectivity modes exhibited by the carboxylato groups, and 6) the stoichiometry of the final products, that is, the Cu(II)/Ln(III)/linker molar ratio. A unique cluster formed by 24 water molecules was found in crystal 11. In compounds 2, 3, 4, 9, and 11 the Cu(II)-Gd(III) exchange interaction was found to be ferromagnetic, with J values in the range of 3.53-8.96 cm(-1). Compound 12 represents a new example of a polynuclear complex containing three different paramagnetic ions. The intranode Cu(II)-Gd(III) ferromagnetic interaction is overwhelmed by the antiferromagnetic interactions occurring between the cyanobridged Gd(III) and Cr(III) ions.     

Syntheses, structures, and magnetic properties of unusual nonlinear polynuclear copper(II) complexes containing derivatives of 1,2,4-triazole and pivalate ligands

Novel polynuclear Cu(II) complexes containing derivatives of 1,2,4-trizaole and pivalate ligands, [Cu(3)(mu(3)-OH)(mu-adetrz)(2)(piv)(5)(H(2)O)].6.5H(2)O (1) (adetrz = 4-amino-3,5-diethyl-1,2,4-triazole, piv = pivalate), [Cu(4)(mu(3)-OH)(2)(mu-atrz)(2)(mu-piv)(4)(piv)(2)].2MeOH.H(2)O (2) (atrz = 4-amino-1,2,4-triazole), [Cu(4)(mu(3)-OH)(2)(mu-tbtrz)(2)(mu-piv)(2)(piv)(4)].4H(2)O (3) (tbtrz = 4-tert-butyl-1,2,4-trizaole), and [Cu(4)(mu(3)-O)(2)(mu-admtrz)(4)(admtrz)(2)(mu-piv)(2)(piv)(2)].2[Cu(2)(mu-H(2)O)(mu-admtrz)(piv)(4)].13H(2)O [4 = 4a.2(4b).13H(2)O; admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole], have been prepared and structurally characterized. 1 is an asymmetrical triangular complex containing a [Cu(3)(mu(3)-OH)] core with two Cu---Cu edges spanned by bridging adetrz ligands. 2, 3, and 4a are novel tetranuclear compounds containing a [Cu(4)(mu(3)-O)(2)] or [Cu(4)(mu(3)-OH)(2)] core with Cu---Cu edges spanned by bridging 1,2,4-triazole or pivalate ligands. 4b is a dinuclear compound with one admtrz and one water bridge, and it is the first dinuclear Cu(II) triazole complex with one bridging water molecule. 1 is one of few reported triangular Cu(II) complexes with derivatives of 1,2,4-triazole, while 2, 3, and 4a are the first group of the nonlinear tetranuclear Cu(II) compounds with derivatives of 1,2,4-triazole. Variable-temperature magnetic susceptibility studies on the powder samples of 1-3 reveal the overall antiferromagnetic coupling between Cu(II) ions with J values of -55.6 to -12.8 cm(-1) (1), -216.4 to 0 cm(-1) (2), and -259.8 to 4.8 cm(-1) (3).     

Nine non-symmetric pyrazine-pyridine imide-based complexes: reversible redox and isolation of [M(II/III)(pypzca)2](0/+) when M = Co, Fe

The non-symmetric imide ligand Hpypzca (N-(2-pyrazylcarbonyl)-2-pyridinecarboxamide) has been deliberately synthesised and used to produce nine first row transition metal complexes: [M(II)(pypzca)(2)], M = Zn, Cu, Ni, Co, Fe; [M(III)(pypzca)(2)]Y, M = Co and Y = BF(4), M = Fe and Y = ClO(4); [Cu(II)(pypzca)(H(2)O)(2)]BF(4), [Mn(II)(pypzca)(Cl)(2)]HNEt(3). These are the first deliberately prepared complexes of a non-symmetric imide ligand. X-ray crystal structures of [Cu(II)(pypzca)(2)]·H(2)O, [Co(II)(pypzca)(2)], [Co(III)(pypzca)(2)]BF(4), [Cu(II)(pypzca)(H(2)O)(2)]BF(4)·H(2)O and [Mn(II)(pypzca)Cl(2)]HNEt(3) show that each of the (pypzca)(-) ligands binds in a meridional fashion via the N(3) donors. In the first three complexes, two such ligands are bound such that the 'spare' pyrazine nitrogen atoms are positioned approximately orthogonally to one another and also to the imide oxygen atoms. In MeCN the [M(II/III)(pypzca)(2)](0/+) complexes, where M = Ni, Co or Fe, exhibit one reversible metal based M(II/III) process and two distinct, quasi-reversible ligand based reduction processes, the latter also observed for M(II) = Zn. [Mn(II)(pypzca)Cl(2)]HNEt(3) displays a quasi-reversible oxidation process in MeCN, along with several irreversible processes. Both copper(II) complexes show only irreversible processes. Variable temperature magnetic measurements show that [Fe(III)(pypzca)(2)]ClO(4) undergoes a gradual spin crossover from partially high spin at 298 K (3.00 BM) to fully low spin at 2 K (1.96 BM), and that [Co(II)(pypzca)(2)] remains high spin from 298 to 4 K. All of the complexes are weakly coloured, other than [Fe(II)(pypzca)(2)] which is dark purple and absorbs strongly in the visible region.     

Dicopper(II) complexes of a new pyrazolate-containing Schiff-base macrocycle and related acyclic ligand

Dicopper(II) complexes of two new 3,5-disubstituted-pyrazole-based ligands, bis(quadridentate) macrocyclic ligand (L1)(2-) and bis(terdentate) acyclic ligand (L2)(-), were synthesised by Schiff base condensation of 3,5-diformylpyrazole and either one equivalent of 1,3-diaminopropane or two equivalents of 2-(2-aminoethyl)pyridine in the presence of one or two equivalents of copper(II) ions, respectively. Copper(II) acetate monohydrate was employed in the synthesis of [Cu(2)(L1)(OAc)(2)], [Cu(2)(L2)(H(2)O)(2)(OAc)(3)] and [Cu(II)(2)(L1)(NCS)(2)]; in the last of these one equivalent of NaNCS per copper(II) ion was also added. The fourth complex, [Cu(2)(L2)(NCS)(2)(DMF)]BF(4), was prepared using copper(II) tetrafluoroborate hexahydrate, along with two equivalents of NaOH and six of NaSCN. All four of these dimetallic complexes have been characterised by single crystal X-ray diffraction: the two macrocyclic complexes are the first such Schiff base complexes to be so characterised. A feature common to all four of the structures is bridging of the two copper(II) centres by the pyrazolate moiety/moieties. The structure determinations show that the coordination mode of the acetate groups in both [Cu(2)(L1)(OAc)(2)].2MeOH.H(2)O and [Cu(2)(L2)(H(2)O)(2)(OAc)(3)] is unidentate as had been tentatively predicted by analysis of the infrared spectra (DeltaOCO of 199 and 208 cm(-1), respectively). The magnetochemical studies of the macrocyclic complexes, over the temperature range 4-300 K, revealed strong antiferromagnetic coupling with J = -169 and -213 cm(-1) for [Cu(2)(L1)(OAc)(2)].2H(2)O and [Cu(II)(2)(L1)(NCS)(2)].DMF respectively. The J values have been discussed in relation to a published correlation involving the CuN(pyrazolate)N(pyrazolate) angles.     

Intra and intermolecular magnetic interactions in a series of dinuclear Cu(II)/hxta complexes [H5hxta = N,N'-(2-hydroxy-1,3-xylylene)-bis-(N-carboxymethylglycine)]: correlation of magnetic properties with geometry

Nine dinuclear copper(II) complexes with hxta5- ligands [H5hxta = N,N'-(2-hydroxy-1,3-xylylene)-bis-(N-carboxymethylglycine)]: [Cu2(MeO-hxtaH)(H2O)2] x 4H2O (1), [Na(micro-H2O)2(H2O)6][Cu2(Cl-hxta)(H2O)3]2 x 6H2O (2), [Cu(H2O)6][Cu2(Me-hxta)(H2O)2](NO3) x 2H2O (3), [Cu2(R-hxtaH)(H2O)3] x 3H2O [R = Cl (4), CH3 (5), and MeO (6)], [Cu2(MeO-hxtaH2)(micro-X)(CH3OH)] x 3CH3OH [X = Cl (7), Br (8)] and K5Na(micro-H2O)10[Cu2(micro-CO3)(Me-hxta)]2 x 4H2O (9), have been synthesized and structurally characterized. In complexes 4-7, the dinuclear units are linked via novel pairwise supramolecular interactions involving the ligand carboxylate groups. The intra- and intermolecular magnetic interactions have been quantified, and the coupling constants have been related to the structural geometries.     

Di- and tetra-nuclear copper(II), nickel(II), and cobalt(II) complexes of four bis-tetradentate triazole-based ligands: synthesis, structure, and magnetic properties

Four bis-tetradentate N(4)-substituted-3,5-{bis[bis-N-(2-pyridinemethyl)]aminomethyl}-4H-1,2,4-triazole ligands, L(Tz1)-L(Tz4), differing only in the triazole N(4) substituent R (where R is amino, pyrrolyl, phenyl, or 4-tertbutylphenyl, respectively) have been synthesized, characterized, and reacted with M(II)(BF(4))(2)·6H(2)O (M(II) = Cu, Ni or Co) and Co(SCN)(2). Experiments using all 16 possible combinations of metal salt and L(TzR) were carried out: 14 pure complexes were obtained, 11 of which are dinuclear, while the other three are tetranuclear. The dinuclear complexes include two copper(II) complexes, [Cu(II)(2)(L(Tz2))(H(2)O)(4)](BF(4))(4) (2), [Cu(II)(2)(L(Tz4))(BF(4))(2)](BF(4))(2) (4); two nickel(II) complexes, [Ni(II)(2)(L(Tz1))(H(2)O)(3)(CH(3)CN)](BF(4))(4)·0.5(CH(3)CN) (5) and [Ni(II)(2)(L(Tz4))(H(2)O)(4)](BF(4))(4)·H(2)O (8); and seven cobalt(II) complexes, [Co(II)(2)(L(Tz1))(μ-BF(4))](BF(4))(3)·H(2)O (9), [Co(II)(2)(L(Tz2))(μ-BF(4))](BF(4))(3)·2H(2)O (10), [Co(II)(2)(L(Tz3))(H(2)O)(2)](BF(4))(4) (11), [Co(II)(2)(L(Tz4))(μ-BF(4))](BF(4))(3)·3H(2)O (12), [Co(II)(2)(L(Tz1))(SCN)(4)]·3H(2)O (13), [Co(II)(2)(L(Tz2))(SCN)(4)]·2H(2)O (14), and [Co(II)(2)(L(Tz3))(SCN)(4)]·H(2)O (15). The tetranuclear complexes are [Cu(II)(4)(L(Tz1))(2)(H(2)O)(2)(BF(4))(2)](BF(4))(6) (1), [Cu(II)(4)(L(Tz3))(2)(H(2)O)(2)(μ-F)(2)](BF(4))(6)·0.5H(2)O (3), and [Ni(II)(4)(L(Tz3))(2)(H(2)O)(4)(μ-F(2))](BF(4))(6)·6.5H(2)O (7). Single crystal X-ray structure determinations revealed different solvent content from that found by microanalysis of the bulk sample after drying under a vacuum and confirmed that 5', 8', 9', 11', 12', and 15' are dinuclear while 1' and 7' are tetranuclear. As expected, magnetic measurements showed that weak antiferromagnetic intracomplex interactions are present in 1, 2, 4, 7, and 8, stabilizing a singlet spin ground state. All seven of the dinuclear cobalt(II) complexes, 9-15, have similar magnetic behavior and remain in the [HS-HS] state between 300 and 1.8 K.     

Spectroscopic characterization, X-ray structure, antimicrobial activity and DFT calculations of novel dipicolinate copper(II) complex with 2,6-pyridinedimethanol

Novel dipicolinate complex of copper(II) ion, [Cu(dmp)(dpc)]·0.8H(2)O [dmp: 2,6-pyridinedimethanol; dpc: dipicolinate or pyridine-2,6-dicarboxylate], has been prepared and fully characterized by single crystal X-ray structure determination. The central copper(II) ion is bonded to dpc and dmp ligands through pyridine nitrogen atom together with two oxygen atom, forming the distorted octahedral geometry. The complex molecules, connected via O-H···O hydrogen bonds, form a supramolecular structure. H(2)dpc, [Cu(dpc)(H(2)O)(3)] and [Cu(dmp)(dpc)]·0.8H(2)O were screened for antimicrobial activity against Gram-positive, Gram-negative bacteria and yeast. H(2)dpc and [Cu(dpc)(H(2)O)(3)] exhibited antibacterial and antifungal activity, while [Cu(dmp)(dpc)]·0.8H(2)O exhibited activity only for Gram-positive bacteria. The geometry optimization and EPR parameters were carried out using the following unrestricted hybrid density functionals: LSDA, BPV86, B3LYP, B3PW91, MPW1PW91, PBEPBE and HCTH. Although the supramolecular interactions have some influences on the molecular geometry in solid state phase, calculated data show that the predicted geometries can reproduce the structural parameters. The electronic station in the frontier orbitals of the copper complex calculated from the experimental data is compared to the results of time-depended DFT calculations with the polarizable continuum model. Calculated vibrational frequencies are consistent with the experimental IR data.     

Combined effects of diamines and carboxylate bridges on structural and magnetic properties of a series of polynuclear copper(II) complexes with 1,1-cyclobutanedicarboxylic acid

Six new copper(II) complexes of formula [Cu(mu-cbdca)(H2O)]n (1) (cbdca = cyclobutanedicarboxylate), [Cu2(mu-cbdca)2(mu-bipy)2]n (2) (bipy = 4,4'-bipyridine), [Cu(mu-cbdca)(mu-bpe)]n (3) (bpe = 1,2-bis(4-pyridyl)ethane), [Cu(mu-cbdca)(bpy)]2 (4) (bpy = 2,2'-bipyridine), [Cu(terpy)(ClO4)]2(mu-cbdca).H2O (5) (terpy = 2,2':6',2' '-terpyridine), and [Cu(cbdca)(phen) (H2O)].2H2O (6) (phen = 1,10-phenanthroline) were obtained and structurally characterized by X-ray crystallography. Complex 1 is a two-dimensional network with a carboxylate bridging ligand in syn-anti (equatorial-equatorial) coordination mode. Complexes 2 and 3 are formed by chains through syn-anti (equatorial-apical) carboxylate bridges, linked to one another by the corresponding amine giving two-dimensional nets. Complexes 4 and 5 are dinuclear, with the copper ions linked by two oxo (from two different carboxylate) bridging ligands in 4 and with only one carboxylate showing the unusual bis-unidentate mode in complex 5. Complex 6 is mononuclear, with the carboxylate linked to copper(II) in a chelated form. Intermolecular hydrogen bonds and pi-pi stacking interactions build an extended two-dimensional network. Magnetic susceptibility measurements of complexes 1-5 in the temperature range 2-300 K show the occurrence of weak ferromagnetic coupling for 1 and 4 (J = 4.76 and 4.44 cm(-1), respectively) and very weak antiferromagnetic coupling for 2, 3, and 5 (J = -0.94, -0.67, and -1.61 cm(-1), respectively). Structural features and magnetic values are compared with those reported for the similar copper(II) malonate and phenylmalonate complexes.     

Helical-chain copper(II) complexes and a cyclic tetranuclear copper(II) complex with single syn-anti carboxylate bridges and ferromagnetic exchange interactions

Tridentate Schiff-base carboxylate-containing ligands, derived from the condensation of 2-imidazolecarboxaldehyde with the amino acids beta-alanine (H2L1) and 2-aminobenzoic acid (H2L5) and the condensation of 2-pyridinecarboxaldehyde with beta-alanine (HL2), D,L-3-aminobutyric acid (HL3), and 4-aminobutyric acid (HL4), react with copper(II) perchlorate to give rise to the helical-chain complexes [[Cu(mu-HL1)(H2O)](ClO4)]n (1), [[Cu(mu-L2)(H2O)](ClO4).2H2O]n (2), and [[Cu(mu-L3)(H2O)](ClO4).2H2O]n (3), the tetranuclear complex [[Cu(mu-L4)(H2O)](ClO4)]4 (4), and the mononuclear complex [Cu(HL5)(H2O)](ClO4).1/2H2O (5). The reaction of copper(II) chloride with H2L1 leads not to a syn-anti carboxylate-bridged compound but to the chloride-bridged dinuclear complex [Cu(HL1)(mu-Cl)]2 (6). The structures of these complexes have been solved by X-ray crystallography. In complexes 1-4, roughly square-pyramidal copper(II) ions are sequentially bridged by syn-anti carboxylate groups. Copper(II) ions exhibit CuN2O3 coordination environments with the three donor atoms of the ligand and one oxygen atom belonging to the carboxylate group of an adjacent molecule occupying the basal positions and an oxygen atom (from a water molecule in the case of compounds 1-3 and from a perchlorate anion in 4) coordinated in the apical position. Therefore, carboxylate groups are mutually cis oriented and each syn-anti carboxylate group bridges two copper(II) ions in basal-basal positions with Cu...Cu distances ranging from 4.541 A for 4 to 5.186 A for 2. In complex 5, the water molecule occupies an equatorial position in the distorted octahedral environment of the copper(II) ion and the Cu-O carboxylate distances in axial positions are very large (>2.78 A). Therefore, this complex can be considered as mononuclear. Complex 6 exhibits a dinuclear parallel planar structure with Ci symmetry. Copper(II) ions display a square-pyramidal coordination geometry (tau = 0.06) for the N2OCl2 donor set, where the basal coordination sites are occupied by one of the bridging chlorine atoms and the three donor atoms of the tridentate ligand and the apical site is occupied by the remaining bridging chlorine atom. Magnetic susceptibility measurements indicate that complexes 1-4 exhibit weak ferromagnetic interactions whereas a weak antiferromagnetic coupling has been established for 6. The magnetic behavior can be satisfactorily explained on the basis of the structural data for these and related complexes.     

Tetradentate bis(o-iminobenzosemiquinonate(1-)) pi radical ligands and their o-aminophenolate(1-) derivatives in complexes of nickel(II), palladium(II), and copper(II)

The coordination chemistries of the potential tetradentate ligands N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)ethylenediamine, H4[L1], the unsaturated analogue glyoxal-bis(2-hydroxy-3,5-di-tert-butylanil), H2[L2], and N,N'-bis(2-hydroxy-3,5-di-tert-butylphenyl)-2,2-dimethylpropylenediamine, H4[L3], have been investigated with nickel(II), palladium(II), and copper(II). The complexes prepared and characterized are [Ni(II)(H3L1)2] (1), [Ni(II)(HL2)2].5/8CH2Cl2 (2), [Ni(II)(L3**)] (3), [Pd(II)(L3**)][Pd(II)(H2L3) (4), and [Cu(II)(H2O)(L4)] (5), where (L4)2- is the oxidized diimine form of (L3)4- and (L3**)2- is the bis(o-iminosemiquinonate) diradical form of (L3)4-. The structures of compounds 1-5 have been determined by single crystal X-ray crystallography. In complexes 1 and 2, the ligands (H3L1)- and (HL2)- are tridentate and the nickel ions are in an octahedral ligand environment. The oxidation level of the ligands is that of an aromatic o-aminophenol. 1 and 2 are paramagnetic (mu(eff) approximately 3.2 mu(B) at 300 K), indicating an S = 1 ground state. The diamagnetic, square planar, four-coordinate complexes 3 and [Pd(II)(L3**)] in 4 each contain two antiferromagnetically coupled o-iminobenzosemiquinonate(1-) pi radicals. Diamagnetic [Pd(II)(H2L3)] in 4 forms an eclipsed dimer via four N-H.O hydrogen bonding contacts which yields a nonbonding Pd.Pd contact of 3.0846(4) A. Complex 5 contains a five-coordinate Cu(II) ion and two o-aminophenolate(1-) halves in (L4)2-. The electrochemistries of complexes 3 and 4a ([Pd(II)(L3**)] of 4) have been investigated, and the EPR spectra of the monocations and -anions are reported.     

Synthesis, X-ray crystal structure and X-band EPR of [Cu(H(2)O)(2)(imH)(4)] x Sq single crystals

The copper salt [Cu(H(2)O)(2)(imH)(4)] x Sq has been synthesized at room temperature. Crystal structure of the [Cu(H(2)O)(2)(imH)(4)] x Sq (Sq is squarete dianion (C(4)O(4)(2-)) and imH is imidazole (C(3)H(4)N(2))) complexes has been investigated by single-crystal X-ray diffraction analyses and the environment of copper ion has been identified by EPR. The single crystal is triclinic with the space group P1. The unit cell dimensions of the crystals are a=9.317 Angstrom, b=9.958 Angstrom, c=12.130 Angstrom, alpha=69.99 degrees , beta=76.61 degrees and gamma=78.13 degrees . The unit cell contains two molecules. The Cu(II) atom has an octahedral arrangement in which the Cu(II) ion lies on the inversion canter and is coordinated by four imidazole ligands with the equatorial plane and two water molecules with the octahedral axial. The complex shows a normal magnetic moment and the single crystal EPR spectra consist of two sets of four hyperfine lines of copper. The ground wave function of the hole of the Cu(2+) is an admixture of d(x(2) - y(2)) and d(z(2)) states.     

Rational assembly of soluble copper(II) phosphonates: synthesis, structure and magnetism of molecular tetranuclear copper(II) phosphonates

The reactions of the dinuclear copper complexes [Cu(2)(L)(OAc)] [H(3)L = N,N'-(2-hydroxypropane-1,3-diyl)bis(salicylaldimine) or [Cu(2)(L')(OAc)] (H(3)L' = N,N'-(2-hydroxypropane-1,3-diyl)bis(4,5-dimethylsalicylaldimine)] with various phosphonic acids, RPO(3)H(2) (R = t-Bu, Ph, c-C(5)H(9), c-C(6)H(11) or 2,4,6-i-Pr(3)-C(6)H(2)), leads to the replacement of the acetate bridge affording tetranuclear copper(II) phosphonates, [Cu(4)(L)(2)(t-BuPO(3))](CH(3)OH)(2)(C(6)H(6)) (1), [Cu(4)(L)(2)(PhPO(3))(H(2)O)(2)(NMe(2)CHO)](H(2)O)(2) (2), [Cu(4)(L')(2)(C(5)H(9)PO(3))](CH(3)OH)(2) (3), [Cu(4)(L')(2)(C(6)H(11)PO(3)](MeOH)(4)(H(2)O)(2) (4) and [Cu(4)(L')(2)(C(30)H(46)P(2)O(5))](PhCH(3)) (5). The molecular structures of 1-4 reveal that a [RPO(3)](2-) ligand is involved in holding the four copper atoms together by a 4.211 coordination mode. In 5, an in situ formed [(RPO(2))(2)O](4-) ligand bridges two pairs of the dinuclear subunits. Magnetic studies on these complexes reveal that the phosphonate ligand is an effective conduit for magnetic interaction among the four copper centers present; a predominantly antiferromagnetic interaction is observed at low temperatures.     

Antisymmetric exchange in triangular tricopper(II) complexes: correlation among structural, magnetic, and electron paramagnetic resonance parameters

Two new trinuclear copper(II) complexes, [Cu(3)(μ(3)-OH)(daat)(Hdat)(2)(ClO(4))(2)(H(2)O)(3)](ClO(4))(2)·2H(2)O (1) and [Cu(3)(μ(3)-OH)(aaat)(3)(H(2)O)(3)](ClO(4))(2)·3H(2)O (2) (daat = 3,5-diacetylamino-1,2,4-triazolate, Hdat = 3,5-diamino-1,2,4-triazole, and aaat = 3-acetylamino-5-amino-1,2,4-triazolate), have been prepared from 1,2,4-triazole derivatives and structurally characterized by X-ray crystallography. The structures of 1 and 2 consist of cationic trinuclear copper(II) complexes with a Cu(3)OH core held by three N,N-triazole bridges between each pair of copper(II) atoms. The copper atoms are five-coordinate with distorted square-pyramidal geometries. The magnetic properties of 1 and 2 and those of five other related 1,2,4-triazolato tricopper(II) complexes with the same triangular structure (3-7) (whose crystal structures were already reported) have been investigated in the temperature range of 1.9-300 K. The formulas of 3-7 are [Cu(3)(μ(3)-OH)(aaat)(3)(H(2)O)(3)](NO(3))(2)·H(2)O (3), {[Cu(3)(μ(3)-OH)(aat)(3)(μ(3)-SO(4))]·6H(2)O}(n) (4), and [Cu(3)(μ(3)-OH)(aat)(3)A(H(2)O)(2)]A·xH(2)O [A = NO(3)(-) (5), CF(3)SO(3)(-) (6), or ClO(4)(-) (7); x = 0 or 2] (aat =3-acetylamino-1,2,4-triazolate). The magnetic and electron paramagnetic resonance (EPR) data have been analyzed by using the following isotropic and antisymmetric exchange Hamiltonian: H = -J[S(1)S(2) + S(2)S(3)] - j[S(1)S(3)] + G[S(1) × S(2) + S(2) × S(3) + S(1) × S(3)]. 1-7 exhibit strong antiferromagnetic coupling (values for both -J and -j in the range of 210-142 cm(-1)) and antisymmetric exchange (G varying from to 27 to 36 cm(-1)). At low temperatures, their EPR spectra display high-field (g < 2.0) signals indicating that the triangles present symmetry lower than equilateral and that the antisymmetric exchange is operative. A magneto-structural study showing a lineal correlation between the Cu-O-Cu angle of the Cu(3)OH core and the isotropic exchange parameters (J and j) has been conducted. Moreover, a model based on Moriya's theory that allows the prediction of the occurrence of antisymmetric exchange in the tricopper(II) triangles, via analysis of the overlap between the ground and excited states of the local Cu(II) ions, has been proposed. In addition, analytical expressions for evaluating both the isotropic and antisymmetric exchange parameters from the experimental magnetic susceptibility data of triangular complexes with local spins (S) of (1)/(2), (3)/(2), or (5)/(2) have been purposely derived. Finally, the magnetic and EPR results of this work are discussed and compared with those of other tricopper(II) triangles reported in the literature.     

左氧氟沙星铜(Ⅱ)配合物的合成及生物活性研究

合成了四个新左氧氟沙星铜(Ⅱ)配合物:[Cu(Lvfx)(Bipy)(H2O)]Cl.4H2O(1),[Cu(Lvfx)(Phen)(H2O)]Cl.5H2O(2),[Cu(Lvfx)(Tatp)(H2O)]Cl.5H2O(3),[Cu(Lvfx)(Dppz)(H2O)]Cl.4.5H2O(4){Lvfx=左氧氟沙星,Bipy=2,2’-联吡啶,Phen=1,10-邻菲罗啉,Tatp=1,4,8,9-四氮三联苯,Dppz=二吡啶并[3,2-a:2’,3’-c]吩嗪},并通过红外光谱法、紫外-可见光谱法、元素分析、原子吸收光谱法、摩尔电导率分析和差热-热重分析对配合物进行了表征。用滤纸片扩散法和试管二倍稀释法分别测试了配合物及配体对大肠杆菌、金黄色葡萄球菌的抗菌活性,结果显示配合物(3)对大肠杆菌具有最佳的抑菌效果。采用荧光光谱法初步研究了配合物与BSA的相互作用。结果表明,四个配合物均对BSA的荧光有较强的猝灭作用,且发生了能量转移,其与BSA的结合常数(K)分别为4.7×102、5.7×103、5.0×103和1.7×103L.mol-1,结合位点n分别为0.59、0.83、0.81和0.69。     

Synthesis and characterization of norfloxacin-transition metal complexes (group 11, IB): spectroscopic, thermal, kinetic measurements and biological activity

The investigation of the new structures of Ag(I), Cu(II) and Au(III) complexes, [Ag(2)(Nor)(2)](NO(3))(2), [Cu(Nor)(2)(H(2)O)(2)]SO(4).5H(2)O and [Au(Nor)(2) (H(2)O)(2)]Cl(3) (where, Nor=norfloxacin) was done during the reaction of silver(I), copper(II) and gold(III) ions with norfloxacin drug ligand. Elemental analysis of CHN, infrared, electronic, (1)H NMR and mass spectra, as well as thermo gravimetric analysis (TG and DTG) and conductivity measurements have been used to characterize the isolated complexes. The powder XRD studies confirm the amorphous nature of the complexes. The norfloxacin ligand is coordinated to Ag(I) and Au(III) ions as a neutral monodentate chelating through the N atom of piperidyl ring, but the copper(II) complex is coordinated through the carbonyl oxygen atom (quinolone group) and the oxygen atom of the carboxylic group. The norfloxacin and their metal complexes have been biologically tested, which resulted in norfloxacin complexes showing moderate activity against the gram positive and gram negative bacteria as well as against fungi.     

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses,crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H₂O)]₂(NO₃)₂···2H₂O (1), [Cu(L)(phen)(H₂O)]₂(ClO₄)₂···2H₂O (2), and [Cu(L)(phen)Br]₂- [Cu(L)(phen)(H₂O)]₂Br₂···6H₂O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu₂ dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.     

Guanine-containing copper(II) complexes: synthesis, X-ray structures and magnetic properties

Three new compounds of formula {[Cu(gua)(H(2)O)(3)](BF(4))(SiF(6))(1/2)}(n) (1), {[Cu(gua)(H(2)O)(3)](CF(3)SO(3))(2).H(2)O}(n) (2) and [Cu(gua)(2)(H(2)O)(HCOO)]ClO(4).H(2)O.1/2HCOOH] (3) [gua = 2-amino-1H-purin-6(9H)-one] showing the unprecedented coordination of neutral guanine, have been synthesised and structurally characterized. The structures of the compounds 1 and 2 contain uniform copper(II) chains of formula [Cu(gua)(H(2)O)(3)](n)(2n+), where the copper atoms are bridged by guanine ligands coordinated via N(3) and N(7). The electroneutrality is achieved by uncoordinated tetrafluoroborate and hexafluorosilicate (1) and triflate (2). Each copper atom in 1 and 2 is five-coordinated in a distorted square pyramidal environment: two water molecules in trans positions and the N(3) and N(7a) nitrogen atoms of two guanine ligands build the basal plane whereas a water molecule fills the axial position. The values of the copper-copper separation across the bridging guanine ligand are 7.183(1) (1) and 7.123(1) A (2). is an ionic salt whose structure is made up of mononuclear [Cu(gua)(2)(H(2)O)(HCOO)](+) cations and perchlorate anions plus water and formic acid as crystallization molecules. The two guanine ligands in the cation are coordinated to the copper centre through the N(9) atom. The copper atom in 3 is four-coordinated with two monodentate guanine molecules in the trans position, a water molecule and a monodenate formate ligand building a quasi square planar surrounding. Magnetic susceptibility measurements for 1 and 2 in the temperature range 1.9-300 K show the occurrence of significant intrachain antiferromagnetic interactions between the copper(ii) ions across the guanine bridge [J = -9.6(1) (1) and -10.3(1) cm(-1) (2) with H = -J summation operator(i)S(i).S(i+1)].     

Synthesis and structural investigation of mono- and polynuclear copper complexes of 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide

The reaction between 2-hydrazinopyridine and ethylisothiocyanate produced 4-ethyl-1-(pyridin-2-yl) thiosemicarbazide (HEPTS). Its reaction with copper fluoride, chloride, bromide, acetate, nitrate, perchlorate, sulfate, carbonate, hydroxide and copper metal produced 15 Cu(II) complexes. The copper metal is easily oxidized in aqueous-ethanol solution of HEPTS giving [Cu(2)(EPTS)(H(2)O)(3)(OH)(3)]EtOH. Different complexes for the same anion were synthesized by controlling the heating time. Characterization by elemental, thermal, magnetic and spectral (electronic, IR, mass and ESR) studies showed the formation of mono-, di-, tri- and tetra nuclear complexes. The room temperature solid state ESR spectra of the complexes show an axial spectrum with d(x)(2)-y(2) ground state, suggesting distorted tetragonal geometry around Cu(II) center. The kinetic and thermodynamic parameters for the different decomposition steps in the complexes were calculated. HEPTS and its Cu(II) complexes showed high activity against gram negative bacteria; [Cu(3)(EPTS)(2)(EtOH)(2)Br(4)] has more activity.     

Effect of terminal N-substitution in 2-oxo-1,2-dihydroquinoline-3-carbaldehyde thiosemicarbazones on the mode of coordination, structure, interaction with protein, radical scavenging and cytotoxic activity of copper(II) complexes

Four 2-oxo-1,2-dihydroquinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H(2)-OQtsc-R, where R = H, Me, Et or Ph) and their corresponding new copper(II) complexes [CuCl(2)(H(2)-OQtsc-H)]·2H(2)O (1), [CuCl(2)(H(2)-OQtsc-Me)]·2H(2)O (2), [CuCl(2)(H(2)-OQtsc-Et)(CH(3)OH)]Cl (3) and [CuCl(H-OQtsc-Ph)]·CH(3)OH (4) have been synthesized in order to correlate the effect of terminal N-substitution on coordination behaviour, structure and biological activity. Single crystal X-ray diffraction studies revealed that the complexes 1, 2 and 3 have square pyramidal geometry around the central metal ion. In the complexes 1 and 2, the copper ion is coordinated by the ligand with ONS donor atoms, one chloride ion in apical position and the other chloride in the basal plane. Complex 3 consists of [CuCl(2)(H(2)-OQtsc-Et)(CH(3)OH)](+) cation and a chloride as counter ion. The copper ion is coordinated by the ligand with ONS donor atoms and by one chloride ion in the basal plane. One methanol molecule is bonded through its neutral oxygen in the apical position. Complex 4 is square planar with the ligand coordinating through uni-negative tridentate ONS(-) and by one chloride ion in the basal plane. The binding of complexes with lysozyme protein was carried out by fluorescence spectroscopy. Investigations of antioxidation properties showed that all the copper(II) complexes have strong radical scavenging properties. The cytotoxicity of the complexes 3 and 4 against NIH 3T3 and HeLa cell lines showed that synergy between the metal and ligands results in a significant enhancement in the cell death with IC(50) of ~10-40 μM. A size dependence of substitution at terminal N in the thiosemicarbazones on the biological activities of the complexes has been observed.