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.     

Synthesis, spectroscopic characterization and thermal behavior of metal complexes formed with N'-(1-(4-hydroxyphenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H3OPAH)

Complexes of Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Zn(II), Hg(II) and U(IV)O(2)(2+) with N'-(1-(4-hydroxyphenyl) ethylidene)-2-oxo-2-(phenylamino) acetohydrazide (H(3)OPAH) are reported and have been characterized by various spectroscopic techniques like IR, UV-visible, (1)H NMR and ESR as well as magnetic and thermal (TG and DTA) measurements. It is found that the ligand behaves as a neutral bidentate, monoanionic tridentate or tetradentate and dianionic tetradentate. An octahedral geometry for [Mn(H(3)OPAH)(2)Cl(2)], [Co(2)(H(2)OPAH)(2)Cl(2)(H(2)O)(4)] and [(UO(2))(2)(HOPAH)(OAc)(2)(H(2)O)(2)] complexes, a square planar geometry for [Cu(2)(H(2)OPAH)Cl(3)(H(2)O)]H(2)O complex, a tetrahedral structure for [Cd(H(3)OPAH)Cl(2)], [Zn(H(3)OPAH)(OAc)(2)] and [Hg(H(3)OPAH)Cl(2)]H(2)O complexes. The binuclear [Ni(2)(HOPAH)Cl(2)(H(2)O)(2)]H(2)O complex contains a mixed geometry of both tetrahedral and square planar structures. The protonation constants of ligand and stepwise stability constants of its complexes at 298, 308 and 318 K as well as the thermodynamic parameters are being calculated. The bond lengths, bond angles, HOMO, LUMO and dipole moments have been calculated to confirm the geometry of the ligand and the investigated complexes. Also, thermal properties and decomposition kinetics of all compounds are investigated. The interpretation, mathematical analysis and evaluation of kinetic parameters (E(a), A, ΔH, ΔS and ΔG) of all thermal decomposition stages have been evaluated using Coats-Redfern and Horowitz-Metzger methods.     

Synthesis, spectroscopic, thermal and antimicrobial studies of some novel metal complexes of Schiff base derived from [N1-(4-methoxy-1,2,5-thiadiazol-3-yl)sulfanilamide] and 2-thiophene carboxaldehyde

Keeping in view the chemotherapeutic of the sulfa-drugs, Schiff base namely 2-thiophene carboxaldehyde-sulfametrole (HL) and its tri-positive and di-positive metal complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV-vis and thermal analysis (TGA and DrTG). The low molar conductance values suggest the non-electrolytic nature of these complexes. IR spectra show that HL is coordinated to the metal ions in a tetradentate manner through hetero five-membered ring-S and azomethine-N, enolic sulfonamide-OH and thiadiazole-N, respectively. Zn(II), Cd(II) and UO2(II) complexes are found to be diamagnetic (as expected). The proposed general formulae of the prepared complexes are [M2X4(HL)(H2O)4] (where M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), X=Cl, [Fe2Cl6(HL)(H2O)2], [(FeSO4)2(HL)(H2O)4] and [(UO2)2(HL) (NO3)4].H2O. The thermal behaviour of these chelates shows that the hydrated complexes loss water of hydration in first step in case of uranium complexes followed loss coordinated water followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as DeltaE*, DeltaH*, DeltaS*, and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The antimicrobial activity of the obtained products was performed using Chloramphenicol and Grisofluvine as standards, indicate that in some cases metallation increase activity than the ligand.     

Bivalent transition metal complexes of o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone: spectroscopic, antibacterial, antifungal activity and thermogravimetric studies

Schiff base complexes of Cu(II), Ni(II) and Zn(II) with the o-hydroxyacetophenone [N-(3-hydroxy-2-naphthoyl)] hydrazone (H(2)o-HAHNH) containing N and O donor sites have been synthesized. Both ligand and its metal complexes were characterized by different physicochemical methods, elemental analysis, molar conductivity ((1)H NMR, (13)C NMR, IR, UV-visible, ESR, MS spectra) and also thermal analysis (TG and DTG) techniques. The discussion of the outcome data of the prepared complexes indicates that the ligand behave as a bidentate and/or tridentate ligand. The electronic spectra of the complexes as well as their magnetic moments suggest octahedral geometries for all isolated complexes. The room temperature solid state ESR spectrum of the Cu(II) complex shows d(x2-y2) as a ground state, suggesting tetragonally distorted octahedral geometry around Cu(II) centre. The molar conductance measurements proved that the complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E(#), ΔH(#), ΔG(#), ΔS(#) are calculated from the DTG curves, for the [Ni(H(O)-HAHNH)(2)] and [Zn(H(2O)-HAHNH)(OAc)(2)]·H(2)O complexes using the Coats-Redfern equation. Also, the antimicrobial properties of all compounds were studied using a wide spectrum of bacterial and fungal strains. The [Cu(Ho-HAHNH)(OAc)(H(2)O)(2)] complex was the most active against all strains, including Aspergillus sp., Stemphylium sp. and Trichoderma sp. Fungi; E. coli and Clostridium sp. Bacteria.     

Potentiometric, spectroscopic and thermal studies on the metal chelates of 1-(2-thiazolylazo)-2-naphthalenol

The synthesis and characterization of Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pd(II) and UO2(II) chelates of 1-(2-thiazolylazo)-2-naphthalenol (TAN) were reported. The dissociation constants of the ligand and the stability constants of the metal complexes were calculated pH-metrically at 25 degrees C and 0.1 M ionic strength. The solid complexes were characterized by elemental and thermal analyses, molar conductance, IR, magnetic and diffuse reflectance spectra. The complexes were found to have the formulae [M(L)2] for M = Mn(II), Co(II), Ni(II), Zn(II) and Cd(II); [M(L)X].nH2O for M = Cu(II) (X = AcO, n = 3), Pd(II) (X = Cl, n = 0) and UO2(II) (X = NO3, n = 0), and [Fe(L)Cl2(H2O)].2H2O. The molar conductance data reveal that the chelates are non-electrolytes. IR spectra show that the ligand is coordinated to the metal ions in a terdentate manner with ONN donor sites of the naphthyl OH, azo N and thiazole N. An octahedral structure is proposed for Mn(II), Fe(III), Co(II), Ni(II), Zn(II), Cd(II) and UO2(II) complexes and a square planar structure for Cu(II) and Pd(II) complexes. The thermal behaviour of these chelates shows that water molecules (coordinated and hydrated) and anions are removed in two successive steps followed immediately by decomposition of the ligand molecule in the subsequent steps. The relative thermal stability of the chelates is evaluated. The final decomposition products are found to be the corresponding metal oxides. The thermodynamic activation parameters, such as E*, delta H*, delta S* and delta G* are calculated from the TG curves.     

Anion-dependent construction of two hexanuclear 3d-4f complexes with a flexible Schiff base ligand

Two hexanuclear 3d-4f Ni-Eu and Cu-Eu complexes [Eu(4)Ni(2)L(2)(OAc)(12)(EtOH)(2)] (1) and [Eu(4)Cu(2)L(2)(OAc)(12)]·2H(2)O (2) are reported which are formed from the salen type Schiff-base ligand H(2)L (H(2)L = N,N'-bis(3-methoxysalicylidene)butane-1,4-diamine). In both complexes, four Eu(3+) cations are bridged by eight OAc(-) groups and the chain is terminated at each end by two ML (M = Ni and Cu) units. The structures of 1 and 2 were determined by single crystal X-ray crystallographic studies and the luminescence properties of the free ligand and metal complexes in solution were measured.     

Insight on spectral,thermal and biological behaviour of some Cu(II) complexes with saturated pentaazamacrocyclic ligands bearing amino acid residues

Journal of Thermal Analysis and Calorimetry - A novel series of Cu(II) complexes with formula M(HLn)(ClO4)2·mH2O [HLn: 13-membered pentaazamacrocyclic ligand resulted from condensation of...     

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.     

Ferromagnetic heterotrinuclear Cu-Ni complexes of a compartmental chiral Schiff base

Nickel(II) and copper(II) acetate react with the trinucleating compartmental Schiff base H(4)L (H(4)L = 6,6'-(E)-3,3'-(ethane-1,2-diyl)bis(1-(2-((E)-3-bromo-5-chloro-2-hydroxybenzylideneamino)ethyl)imidazolidine-3,2-diyl)bis(2-bromo-4-chlorophenol)) to produce the heterotrinuclear complexes [Ni(2)CuL(OAc)(2)]·0.25H(2)O·2.5MeOH (1·0.25H(2)O·2.5MeOH) and [NiCu(2)L(OAc)(2)]·3.25H(2)O·0.5MeOH (2·3.25H(2)O·0.5MeOH) as a function of the Ni(OAc)(2)?:?Cu(OAc)(2) molar ratio. The crystal structures of H(4)L, 1·0.25H(2)O·2.5MeOH and 2·3.25H(2)O·0.5MeOH could be solved. The free ligand presents two stereogenic methine groups on the imidazolidine heterocycles. X-Ray diffraction studies on H(4)L determined that the solved crystal structure corresponds to a racemate formed by the (2R,2'R) and (2S,2'S) enantiomers, without detecting the (2R,2'S) diastereoisomer. The crystal structures of both heterotrinuclear complexes reveal that Ni(II) has a preference for the central ligand pocket, showing that this cavity discriminates between Ni(II) and Cu(II) when both species are present in the reaction medium. These results are validated by DFT calculations. As a consequence of the coordination, 1·0.25H(2)O·2.5MeOH and 2·3.25H(2)O·0.5MeOH are also chiral, but crystallise as racemates. In addition to their asymmetric methine groups, these complexes present four other stereogenic centres: the four coordinated imidazolidine N atoms. The luminescent properties of the ligand and both complexes were analysed, showing that the presence of the metals partially inhibits the emission of the ligand and apparently tunes the position of the secondary fluorescence emission band. The magnetic characterisation of 1·0.25H(2)O·2.5MeOH and 2·3.25H(2)O·0.5MeOH was also performed, showing the ferromagnetic behaviour of both complexes.     

刚性配体2,2-联吡啶诱导的双咪唑金属超分子配合物的合成与晶体结构

合成了3种新的超分子配合物[Cd(H2biim)(2,2'-bipy)(NO3)2] (1), [Cu(H2biim)(2,2'-bipy)(H2O)](NO3)2 (2)和[Zn(H2biim)(2,2'-bipy)(H2O)](NO3)2 (3) (H2biim＝双咪唑; 2,2'-bipy＝2,2'-联吡啶), 并通过X射线单晶衍射测定了其结构. 配合物1～3均为单斜晶系, 属于P2(1)/c空间群, 在1中, Cd(II)为六配位, 它与双咪唑的2个氮原子, 联吡啶的2个氮原子和2个硝酸根的2个氧原子配位. 在2和3中, Cu(II)和Zn(II)均为五配位的, 它们与双咪唑的2个氮原子、2,2'-联吡啶的两个氮原子和一个水分子配位. 1～3的对称单元均通过双咪唑、硝酸根和水之间形成的氢键R21(7), R21(4) 和R44(18)构筑了1D链状超分子.     

Environmental control of solution speciation in cobalt(II) 2,2':6',2'-terpyridine complexes: anion and solvent dependence

In methanol or chloroform/methanol solutions, reactions of Cltpy or MeOtpy (Rtpy = 4'-R-2,2':6',2'-terpyridine) with CoX(2)·xH(2)O (X(-) = Cl(-), [OAc](-), [NO(3)](-) or [BF(4)](-)) result in the formation of equilibrium mixtures of [Co(Rtpy)(2)](2+) and [Co(Rtpy)X(2)]. A study of the solution speciation has been carried out using (1)H NMR spectroscopy, aided by the dispersion of signals in the paramagnetically shifted spectra; on going from a low- to high-spin cobalt(II) complex, proton H(6) of the tpy ligand undergoes a significant shift to higher frequency. For R = Cl and X(-) = [OAc](-), increasing the amount of CD(3)OD in the CD(3)OD/CDCl(3) solvent mixture affects both the relative proportions of [Co(Cltpy)(2)](2+) and [Co(Cltpy)(OAc)(2)] and the chemical shifts of the (1)H NMR resonances arising from [Co(Cltpy)(OAc)(2)]. When the solvent is essentially CDCl(3), the favoured species is [Co(Cltpy)(OAc)(2)]. For the 4'-methoxy-2,2':6',2'-terpyridine, the speciation of mono- and bis(terpyridine)cobalt(II) complexes depends upon the anion, solvent and ligand:Co(2+) ion ratio. The (1)H NMR spectrum of [Co(MeOtpy)(2)](2+) is virtually independent of anion and solvent. In contrast, the signals arising from [Co(MeOtpy)X(2)] depend on the anion and solvent. In the case of X(-) = [BF(4)](-), we propose that the mono(tpy) complex formed in solution is [Co(MeOtpy)L(n)](2+) (L = H(2)O or solvent, n = 1-3). The formation of mono(tpy) species has been confirmed by the solid state structures of [Co(Cltpy)(OAc-O)(OAc-O,O')], [Co(MeOtpy)(OAc-O)(OAc-O,O')], [Co(MeOtpy)(NO(3)-O)(2)(OH(2))] and [Co(MeOtpy)Cl(2)]. The single crystal structure of the cobalt(III) complex [Co(Cltpy)Cl(3)]·CHCl(3) is also reported.     

Metal complexes of Schiff base derived from sulphametrole and o-vanilin. Synthesis, spectral, thermal characterization and biological activity

Metal complexes of Schiff base derived from condensation of o-vanilin (3-methoxysalicylaldehyde) and sulfametrole [N(1)-(4-methoxy-1,2,5-thiadiazole-3-yl)sulfanilamide] (H2L) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV-vis and thermal analysis (TGA). From the elemental analyses data, the complexes were proposed to have the general formulae [M2X3(HL)(H2O)5].yH2O (where M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), X=Cl, y=0-3); [Fe2Cl5(HL)(H2O)3].2H2O; [(FeSO4)2(H2L)(H2O)4] and [(UO2)2(NO3)3(HL)(H2O)].2H2O. The molar conductance data reveal that all the metal chelates were non-electrolytes. The IR spectra show that, H2L is coordinated to the metal ions in a tetradentate manner with ON and NO donor sites of the azomethine-N, phenolic-OH, enolic sulphonamide-OH and thiadiazole-N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Salmonella typhi, Bacillus subtillus, Staphylococcus aureus and Fungi (Aspergillus terreus and Aspergillus flavus). The activity data show that the metal complexes to be more potent/antimicrobial than the parent Shciff base ligand against one or more microbial species.     

Metal-catalysed oxidation processes in thiosemicarbazones: new complexes with the ligand N-{2-([4-N-ethylthiosemicarbazone]methyl)phenyl}-p-toluenesulfonamide

The coordination behaviour of a new thiosemicarbazone Schiff-base building block, N-{2-([4-N-ethylthiosemicarbazone]methyl)phenyl}-p-toluenesulfonamide, H2L1 (1), incorporating a bulky tosyl group, towards Mn II, Fe II, Co II, Ni II, Cu II, Zn II, Cd II, Ag I, Sn II, and Pb II has been investigated by means of an electrochemical preparative procedure. Most metal complexes of L1 have the general formula [M(L1)]2.nX (M=Mn, Fe, Co, Ni, Cu, Cd, Pb; n=0-4, X=H2O or CH3CN), as confirmed by the structure of [Pb(L1)]2 (15), in which the lone pair on lead is stereochemically active. This lead(II) complex shows an intense fluorescence emission with a quantum yield of 0.13. In the case of silver, the complex formed was found to possess a stoichiometry of [Ag2(L1)]2.3H2O. During reactions with manganese and copper metals, interesting catalysed processes have been found to take place, with remarkable consequences regarding the ligand skeleton structure. In synthesising the manganese complex, we obtained an unexpected dithiolate thiosemicarbazone tosyl ligand, H2L2, as a side-product, which has been fully characterised, including by X-ray diffraction analysis. In the case of copper, the solid complex has the formula [CuL1]2, but the crystallised product shows the copper atoms coordinated to a new cyclised thiosemicarbazone ligand, H2L3, as in the structures of the complexes [Cu(L3)]2.CH3CN (8) and [Cu(L3)(H2O)]2.CH3CN.H2O (9). The zinc complex [Zn(L1)]4 (12) displays a particular tetranuclear zeolite-type structure capable of hosting small molecules or ions, presumably through hydrogen bonding.     

Preparation, characterization and biological activity of Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO(2)(II) complexes of new cyclodiphosph(V)azane of sulfaguanidine

Novel hexachlorocyclodiphosph(V)azane of sulfaguanidine, H(4)L, l,3-[N'-amidino-sulfanilamide]-2,2,2,4,4,4-hexachlorocyclodiphosph(V)azane was prepared and its coordination behaviour towards the transition metal ions Fe(III), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and UO(2)(II) was studied. The structures of the isolated products are proposed based on elemental analyses, IR, UV-vis, (1)H NMR, mass spectra, reflectance, magnetic susceptibility measurements and thermogravimetric analysis (TGA). The hyperfine interactions in the isolated complex compounds were studied using 14.4keV gamma-ray from radioactive (57)Co (M?ssbauer spectroscopy). The data show that the ligand are coordinated to the metal ions via the sulfonamide O and deprotonated NH atoms in an octahedral manner. The H(4)L ligand forms complexes of the general formulae [(MX(z))(2)(H(2)L)H(2)O)(n)] and [(FeSO(4))(2) (H(4)L) (H(2)O)(4)], where X=NO(3) in case of UO(2)(II) and Cl in case of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II). The molar conductance data show that the complexes are non-electrolytes. The thermal behaviour of the complexes was studied and different thermodynamic parameters were calculated using Coats-Redfern method. Most of the prepared complexes showed high bactericidal activity and some of the complexes show more activity compared with the ligand and standards.     

Metal-free and dicopper(II) complexes of Schiff base [2 + 2] macrocycles derived from 2,2'-iminobisbenzaldehyde: syntheses, structures, and electrochemistry

Three new bis-terdentate Schiff base [2 + 2] macrocycles (H(2)L(Et), H(2)L(Pr), and H(2)L(Bu)) have been prepared in high yields by 1:1 condensation of 2,2'-iminobisbenzaldehyde with 1,2-diaminoethane, 1,3-diaminopropane, and 1,4-diaminobutane, respectively. Metalation of these macrocycles yields the corresponding dicopper(II) acetate (1, 2, and 3) and tetrafluoroborate (4, 5, and 6) complexes. The structures of H(2)L(Et), H(2)L(Pr), H(2)L(Bu), [Cu(II)(2)L(i)(OAc)(2)]·solvents (where i is Et, Pr or Bu) and [Cu(II)(2)L(Pr)(DMF)(4)] (BF(4))(2)·0.5H(2)O are reported. Intramolecular hydrogen bonding is a feature of the metal-free macrocycles. The copper(II) centers in [Cu(II)(2)L(i)(OAc)(2)]·solvents are four coordinate, and the macrocycles have U-shaped (Et, Bu) or stepped (Pr) conformations. Complex 5 crystallizes with two dimethylformamide (DMF) molecules bound per five coordinate copper(II) center. Electrochemical studies revealed ligand based oxidations for all of the macrocycles and complexes. Complexes 1 and 2 undergo two quasi-reversible oxidations in DCM which are associated with the deposition of a visible film on the electrode after multiple scans in this oxidative region, suggestive of electropolymerization. Complexes 4-6, studied in MeCN, have Cu(II) → Cu(I) redox potentials at more positive potentials than for 1-3.     

Structural and thermal characterization of ternary complexes of piroxicam and alanine with transition metals: uranyl binary and ternary complexes of piroxicam. Spectroscopic characterization and properties of metal complexes

Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO2(II) complexes with piroxicam (Pir) drug (H2L1) and dl-alanine (Ala) (HL2) and also the binary UO2(II) complex with Pir were studied. The structures of the complexes were elucidated using elemental, IR, molar conductance, magnetic moment, diffused reflectance and thermal analyses. The UO2(II) binary complex was isolated in 1:2 ratio with the formula [UO2(H2L)2](NO3)2. The ternary complexes were isolated in 1:1:1 (M:H2L1:L2) ratios. The solid complexes were isolated in the general formulae [M(H2L)(L2)(Cl)n(H2O)m].yH2O (M=Fe(III) (n=2, m=0, y=1), Co(II) (n=1, m=1, y=2) and Ni(II) (n=1, m=1, y=0)); [M(H2L)(L2)](X)z.yH2O (M=Cu(II) (X=AcO, z=1, y=0), Zn(II) (X=AcO, z=1, y=3) and UO2(II) (X=NO3, z=1, y=2)). Pir behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data show that the complexes have octahedral geometry except Cu(II) and Zn(II) complexes have tetrahedral structures. The thermal decomposition of the complexes was discussed in relation to structure, and the thermodynamic parameters of the decomposition stages were evaluated.     

Synthesis, characterization and thermal studies on metal complexes of new azo compounds derived from sulfa drugs

Four new azo ligands, L1 and HL2-4, of sulfa drugs have been prepared and characterized. [MX(2)(L1)(H(2)O)(m)].nH(2)O; [(MX(2))(2)(HL2 or HL3)(H(2)O)(m)].nH(2)O and [M(2)X(3)(L4)(H(2)O)].nH(2)O; M=Co(II), Ni(II) and Cu(II) (X=Cl) and Zn(II) (X=AcO); m=0-4 and n=0-3, complexes were prepared. Elemental and thermal analyses (TGA and DTA), IR, solid reflectance spectra, magnetic moment and molar conductance measurements have accomplished characterization of the complexes. The IR data reveal that HL1 and HL2-3 ligands behave as a bidentate neutral ligands while HL4 ligand behaves as a bidentate monoionic ligand. They coordinated to the metal ions via the carbonyl O, enolic sulfonamide S(O)OH, pyrazole or thiazole N and azo N groups. The molar conductance data reveal that the chelates are non-electrolytes. From the solid reflectance spectra and magnetic moment data, the complexes were found to have octahedral, tetrahedral and square planar geometrical structures. The thermal behaviour of these chelates shows that the water molecules (hydrated and coordinated) and the anions are removed in a successive two steps followed immediately by decomposition of the ligand in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the TG curves applying Coats-Redfern method.     

Heterobimetallic molecular cages for the deposition of Cu/Ti and Cu/Zn mixed-metal oxides

Heterobimetallic molecular precursors [Ti4(dmae)6(mu-OH)(mu-O)6Cu6(OAc)9.H2O] (1) and [Zn7(OAc)10(mu-OH)6Cu5(dmae)4Cl4] (2) for the deposition of metal oxide thin films of Cu6Ti4O12 (Cu3TiO4, TiO2) and Cu5Zn7O12 (ZnO, CuO) were prepared by the interaction of Ti(dmae)4 with Cu(OAc)2.2H2O for 1 and tetrameric (N,N-dimethylamino)ethanolatocopper(II) chloride, [(dmae)CuCl]4 [where dmae = (N,N-dimethylamino)ethanolate] with Zn(OAc)2.2H2O (where OAc = acetate) for 2 in dry toluene. Both complexes were characterized by melting point, elemental analysis, Fourier transform IR, fast atom bombardment mass spectrometry, thermal analysis (TGA), and single-crystal X-ray diffraction. TGA and XRD prove that complexes 1 and 2 undergo facile thermal decomposition at 300 and 460 degrees C to form thin films of Cu/Ti and Cu/Zn mixed-metal oxides, respectively. Scanning electron microscopy and XRD of the thin films suggest the formation of impurity-free crystallite mixtures of Cu3TiO4 and TiO2, with average crystallite sizes of 22.2 nm from complex 1 and of ZnO and CuO with average crystallite sizes of 26.1 nm from complex 2.     

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.     

Facile in situ synthesis of nanofluids based on ionic liquids and copper oxide clusters and nanoparticles

Two stable nanofluids comprising of mixed valent copper(I,II) oxide clusters (<1 nm) suspended in 1-butyl-3-methylimidazolium acetate, [C(4)mim][OAc], and copper(II) oxide nanoparticles (<50 nm) suspended in trioctyl(dodecyl)phosphonium acetate, [P(8 8 8 12)][OAc], were synthesised in a facile one-pot reaction from solutions of copper(II) acetate hydrate in the corresponding ionic liquids. Formation of the nanostructures was studied using (13)C NMR spectroscopy and differential scanning calorimetry (DSC). From a solution of Cu(OAc)(2) in 1-ethyl-3-methylimidazolium acetate, [C(2)mim][OAc], crystals were obtained that revealed the structure of [C(2)mim][Cu(3)(OAc)(5)(OH)(2)(H(2)O)]·H(2)O, indicating the formation of copper hydroxo-clusters in the course of the reaction. Synthesised nanostructures were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Physical properties of the prepared IL-nanofluids were examined using IR and UV-VIS spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and densitometry.