Acetato, formato and chloride copper(II) complexes with 2-(aminomethyl)pyridine: Synthesis, crystal structure, magnetic properties and EPR results

By the reactions of Cu(OAc)₂ · H₂O and Cu(HCOO)₂ · 4H₂O with 2-(aminomethyl)pyridine in different proportions, the compounds Cu(OAc)₂(2-amp) (1), Cu(HCOO)₂(2-amp) (2), Cu(HCOO)₂(2-amp)_1/2 (5), Cu(OAc)₂(2-amp)₂ · H₂O (6) and Cu(HCOO)₂(2-amp)₂ · H₂O (7) were obtained. In 1 the copper shows an elongated rhombic octahedral stereochemistry determined by a 2-amp molecule and two asymmetrical bidentate acetate groups. The hydrogen bonds between the NH₂ groups and O atoms yield to the formation of a double chain. Compound 2 instead consists in monodimensional chains of Cu(2-amp)(HCOO) units, with monodentate formate groups, linked by syn-anti bridging formate groups. Sheets are formed by hydrogen bonds between the chains. By crystallization of a solution of 6 in chloroform, CuCl₂(2-amp)₂ (3) was obtained. It presents a highly distorted square pyramidal geometry around the copper atom. The sheets, formed by the hydrogen bonds between NH₂ and Cl, are interpenetrated and shows π stacking. Magnetic properties and EPR spectra for these new compounds have been studied. Also the magnetic behaviour of Cu(OAc)₂(2-amp)_1/2 (4) is described.     

Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H₂O)] · 2H₂O (H₃Sas = N-(2-hydroxybenzyl)-l-aspartic acid) (1), [Cu(HMeSglu)(H₂O)] · 2H₂O (H₃MeSglu = (N-(2-hydroxy-5-methylbenzyl)-l-glutamic acid) (2), [Cu₂(Smet)₂] (H₂Smet = (N-(2-hydroxybenzyl)-l-methionine) (3), [Ni(HSas)(H₂O)] (4), [Ni₂(Smet)₂(H₂O)₂] (5), and [Ni(HSapg)₂] (H₂Sapg = (N-(2-hydroxybenzyl)-l-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6.     

Crystal structure, thermal stability and theoretical investigation on four 1,3-bis(1,2,4-triazol-1-yl)propane-based copper(II) complexes

Self-assembly of flexible 1,3-bis(1,2,4-triazol-1-yl)propane (btp), inorganic Cu(II) salt and rigid benzene-based carboxylate coligand generates four complexes, {[Cu(btp)₂(CH₃OH)(H₂O)]·H₂O·2ClO₄}_n (1), {[Cu(btp)(Hbtc)₂]·0.5H₂O}_n (2), [Cu(btp)₂(H₃btea)₂]_n (3), and [Cu(btp)(nb)₂] (4) (H₃btc = 1,3,5-benzenetricarboxylic acid, H₄btea = 1,2,4,5-benzenetetracarboxylic acid, Hnb = p-nitrobenzoic acid), which are fully structural characterized by single-crystal X-ray crystallography, elemental analysis, IR, and TG-DTA techniques. Structural determinations reveal that the polymeric two-dimensional (2D) Cu-btp grid-like layer for 1, 1D linear single- and double-stranded chains for 2 and 3, as well as the discrete binuclear structure for 4, are jointly directed by the coordination polyhedrons of the Cu(II) ion and the exo-bidentate bridging btp core ligand with various conformations. The theoretical calculations suggest that the trans-trans btp is the most stable conformation, and the metal binding site is collectively determined by the electron density of N donors and the spatial orientation of the btp ligand. Unexpectedly, the polycarboxylate anions in 1-4 can only act as terminal coligands not popular bridging connectors. The thermal stability of the resulting complexes is also compared.     

Four copper(II) coordination polymers with a tetrachlorinated benzenedicarboxylate ligand: Solvent effect on diversiform supramolecular arrays

To further investigate the solvent effect on the structures of coordination polymers, a series of polymeric Cu^II complexes have been synthesized and characterized by single-crystal diffraction through combining of 2,3,5,6-tetrachloro-1,4-benzenedicarboxylic acid (H₂BDC-Cl₄) with Cu^II perchlorate. The products including {[Cu(BDC-Cl₄)(py)₃] · H₂O}_n (py = pyridine) (1), {[Cu(BDC-Cl₄)(dioxane)(H₂O)₂] · dioxane}_n (2), and {[Cu₂(BDC-Cl₄)₂(DMF)₄] · 2G}_n (G = MeOH in 3 and G = EtOH in 4) have been obtained in different mixed solvents systems. With the change of the solvent system from pyridine/H₂O (1:1) into dioxane/H₂O (1:1), the infinite 1-D Cu^II-BDC-Cl₄ chain motif in 1 is tuned into the 2-D (4,4) layered structure in 2 with the coordination of dioxanes to copper atoms. When the solvent system is changed into DMF/MeOH (1:1), then into DMF/EtOH (1:1), similar 1-D Cu^II-BDC-Cl₄ double chains are afforded in 3 and 4 with different solvents inclusion. Moreover, the judicious choice of binding-guests leads to numerous coordination geometries of Cu^II centers and final dissimilar supramolecular lattices of 1-4 from 1-D to 3-D via robust hydrogen-bonding interactions. The spectroscopic, thermal, and fluorescent properties of 1-4 have also been investigated.     

Mononuclear and dinuclear model hydrolases of nickel and cobalt

Reaction between the dinuclear model hydrolases [M₂(μ-OAc)₂(OAc)₂(μ-H₂O)(tmen)₂]; M = Ni (1); M = Co (2) and trimethylsilyltrifluoromethanesulphonate (TMS-OTf) under identical reaction conditions gives the mononuclear complex [Ni(OAc)(H₂O)₂(tmen)][OTf] · H₂O (3) in the case of nickel and the dinuclear complex [Co₂(μ-OAc)₂(μ-H₂O)₂(tmen)₂][OTf]₂ (4) in the case of cobalt.Reaction of (3) with urea gives the previously reported [Ni(OAc)(urea)₂(tmen)][OTf] (5), whereas (4) gives [Co₂(OAc)₃(urea)(tmen)₂][OTf] (6) previously obtained by direct reaction of (2) with urea. Both (3) and (4) react with monohydroxamic acids (RHA) to give the dihydroxamate bridged dinuclear complexes [M₂(μ-OAc)(μ-RA)₂(tmen)₂][OTf]; M = Ni (7); M = Co (8) previously obtained by the reaction of (1) and (2) with RHA, illustrating the greater ability of hydroxamic acids to stabilize dinuclear complexes over that of urea by means of their bridging mode, and offering a possible explanation for the inhibiting effect of hydroxamic acids by means of their displacing bridging urea in a possible intermediate invoked in the action of urease.     

Hydrothermal crystallisation of metal (II) orotates (M=nickel, cobalt, manganese or zinc). Effect of 2,2-bipyridyl, 2,2-dipyridyl amine, 1-methyl-3-(2-pyridyl)pyrazole, phenanthroline and 2,9-dimethyl-1,10-phenanthroline upon structure

Hydrothermal synthesis of orotic acid (H₃L) with Ni(OAc)₂·4H₂O gives a green 1D co-ordinative network of composition [Ni(HL)(H₂O)₃] (3). The kinetic product [Ni(HL)·(H₂O)₄]H₂O (4) can be prepared by conventional crystallisation. When boiled in water it is transformed into the thermodynamically favoured trihydrate 3. An unstable blue phase 5 that could not be characterised was also observed. Hydrothermal synthesis of orotic acid and M(OAc)₂·4H₂O (M=Ni, Co, Mn or Zn) and either 2,2-bipyridyl (bipy), 2,2-dipyridylamine (dpa), phenanthroline (phen), methyl-3-(2-pyridyl)pyrazole (pypz) or 2,9-dimethyl-1,10-phenanthroline (dmphen) gave infinite 1D co-ordinative networks of composition [M(HL)bipy(H₂O)] (M=Co or Mn) (6-7) and complexes of composition [Ni(HL)bipy (H₂O)₂]2H₂O (8); [Ni(HL)(dpa)(H₂O)₂]H₂O (9); [Ni(HL)(phen)(H₂O)₂]·2H₂O (10); [Ni(HL)(C₉H₉N₃)(H₂O)₂]·2H₂O (11); [Ni(HL)(dmphen)(H₂O)] (12); [Zn(HL)bipy(H₂O)] (13) and [Ni(HL)(dpa)₂]·0.5H₂O (14).     

Synthesis and properties of new trinuclear Mo(II) complexes containing imidazole and benzimidazole ferrocene units

The reaction of FcCOCl (Fc = (C₅H₅)Fe(C₅H₄)) with benzimidazole or imidazole in 1:1 ratio gives the ferrocenyl derivatives FcCO(benzim) (L1) or FcCO(im) (L2), respectively. Two molecules of L1 or L2 can replace two nitrile ligands in [Mo(η³-C₃H₅)(CO)₂(CH₃CN)₂Br] or [Mo(η³- C₅H₅O)(CO)₂(CH₃CN)₂Br] leading to the new trinuclear complexes [Mo(η³-C₃H₅)(CO)₂(L)₂Br] (C1 for L = L1; C3 for L = L2) and [Mo(η³-C₅H₅O)(CO)₂(L)₂Br] (C2 for L = L1; C4 for L = L2) with L1 and L2 acting as N-monodentade ligands. L1, L2 and C2 were characterized by X-ray diffraction studies. [Mo(η³-C₅H₅O)(CO)₂(L1)₂Br] was shown to be a trinuclear species, with the two L1 molecules occupying one equatorial and one axial position in the coordination sphere of Mo(II). Cyclic voltammetric studies were performed for the two ligands L1 and L2, as well as for their molybdenum complexes, and kinetic and thermodynamic data for the corresponding redox processes obtained. In agreement with the nature of the frontier orbitals obtained from DFT calculations, L1 and L2 exhibit one oxidation process at the Fe(II) center, while C1, C3, and C4 display another oxidation wave at lower potentials, associated with the oxidation of Mo(II).     

3D supramolecular network assembly and thermal decomposition of new copper(II) complexes with pyrazine-2,6-dicarboxylic acid

Four new Cu(II) complexes [Cu(pzda)(2,2′-bpy)(H₂O)] · 2.5H₂O (1), [Cu(pzda)(phen)(H₂O)] · H₂O (2), [Cu(pzda)(4,4′-bpy)] · H₂O (3) and [Cu(pzda)(bpe)_0.5(H₂O)] (4) were synthesized by hydrothermal reactions of copper salt (acetate or sulphate) with pyrazine-2,6-dicarboxylic acid (H₂pzda), and 2,2′-bipyridine (2,2′-bpy), 1,10-phenanthroline (phen), 4,4′-bipyridine (4,4′-bpy) or 1,2-bis(4-pyridyl)-ethane (bpe), respectively. For 1 and 2, they are both monomeric entities which are further assembled into 3D supramolecular networks by hydrogen bonds and π-π stacking interactions. Complex 3 has a 2D metal-organic framework which is connected into 3D supramolecular network by hydrogen bonds. However, for 4, the bpe ligand bridges two Cu(II) ions into binuclear unit, and then the binuclear molecules are assembled into 3D supramolecular network by hydrogen bonds between the coordination water molecule and the carboxylate oxygen atoms. The thermal decomposition mechanism of complexes 1 and 2 cooperated with powder XRD at different temperatures is discussed. The results reveal that once liberation of water molecules takes place the supramolecular network of 1 and 2 collapses.     

Synthesis and crystal structures of di- and tetra-nuclear dicarboxylate-bridged copper(II) complexes

Three new Cu(II) complexes, [Cu₂(C₃H₂O₄)(phen)₂(H₂O)₃](NO₃)₂(H₂O)₂ (1) (C₃H₂O₄ = malonate, phen = 1,10-phenanthroline), [Cu₂(C₄H₄O₄)(phen)₂(H₂O)₂](NO₃)₂ (2) (C₄H₄O₄ = succinate), and {[Cu₂(phen)₂(H₂O)(NO₃)]₂(C₅H₆O₄)₂}(NO₃)₂ (3) (C₅H₆O₄ = glutarate) have been synthesized and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single crystal X-ray diffraction. The X-ray analysis reveals that the structures of 1 and 2 are of dinuclear copper(II) complexes bridged by malonate and succinate dianions, respectively, and 3 is a tetranuclear species formed by two {[Cu₂(phen)₂(H₂O)(NO₃)](C₅H₆O₄)} fragments. The copper ions in 1 and 3 show square-pyramidal coordination geometry, while the copper ions in 2 exhibit a square planar geometry. In each complex, the dicarboxylate ligand is coordinated to copper ions as a chelate and monodentate (1), bis-monodentate (2), and bis-bridging ligand toward the copper ions with syn-syn coordination mode (3).     

Potential tridentate salicylaldehyde hydrazone of arylalkanoic acid coordinate to copper(II) acting as dinegative tetradentate ligands

A chiral Schiff base N-(S)-2-(6-methoxylnaphthyl)-propanoyl-N′-(2-hydroxylbenzylidene)hydrazine (H₂L) has been synthesized. Reaction of H₂L with Cu(OAc)₂ · H₂O led to the formation of a metal complex {[CuL] · H₂O · 2DMF}_∞ (1). In complex 1, the potential dinegative tridentate L²⁻ ligand acting as tetradentate bridging ligand coordinate to two metal ions so as to form a novel infinite metal-organic coordination chain structure. The enantiomerically pure ligand H₂L presents two different sets of signals in the ¹H NMR spectrum either in chloroform solution or in dimethylsulfoxide solution, showing the presence of both (E) and (Z) isomers. The X-ray structural investigations of H₂L revealed that it is the fully extended E-configuration in the solid state.     

Syntheses, structures and properties of copper(II) complexes containing N-(2-hydroxybenzyl)-amino amide ligands

Four copper(II) complexes containing the reduced Schiff base ligands, namely, N-(2-hydroxybenzyl)-glycinamide (Hsglym) and N-(2-hydroxybenzyl)-l-alaninamide (Hsalam) have been synthesized and characterized. The crystal structures of [Cu₂(sglym)₂Cl₂] (1), [Cu₂(salam)₂(NO₃)₂] · H₂O (3), [Cu₂(salam)₂(NO₃)(H₂O)](NO₃) · 1.5H₂O (4), [Cu₂(salam)₂](ClO₄)₂ · 2H₂O (5) show that the Cu(II) atoms are bridged by two phenolato oxygen atoms in the dimers. The sglym ligand bonded to Cu(II) in facial manner while salam ligand prefers to bind to Cu(II) in meridonal geometry. Variable temperature magnetic studies of 3 showed it is antiferromagnetic. These Cu(II) complexes and [Cu₂(sglym)₂(NO₃)₂] (2), exhibit very small catecholase activity as compared to the corresponding complexes containing acid functional groups.     

Synthesis, structures and magnetic properties of nicotinato-copper(II) complexes with polybenzimidazole and polyamine ligands

Four novel nicotinato-copper(II) complexes containing polybenzimidazole and polyamine ligands were synthesized with formula [Cu₂(bbma)₂(nic)₂](ClO₄)₂·CH₃OH·0.5H₂O (1), [Cu₂(dien)₂(nic)₂](ClO₄)₂·2CH₃OH (2), [Cu(ntb)(nic)]ClO₄·H₂O (3) and [Cu(tren)(nic)]BPh₄·CH₃OH·H₂O (4), in which bbma is bis(benzimidazol-2-yl-methyl)amine, dien is diethylenetriamine, ntb is tris(2-benzimidazolylmethyl)amine, tren is tris(2-aminoethyl)amine and nic is nicotinate anion. All of the complexes were characterized by elemental analysis, IR and X-ray diffraction analysis. Complexes 1 and 2 contain centrosymmetric dinuclear entity with the two Cu(II) atoms bridged by two nicotinate anions in an anti-parallel mode. The Cu···Cu separation is 7.109 Å for 1 and 6.979 Å for 2. Complexes 3 and 4 are mononuclear with nicotinate coordinated to Cu(II) ion by the carboxylate O atom in 3 and the pyridine N atom in 4. All of the complexes exhibit abundant hydrogen bonds to form 1D chain for 1, 3, 4 and 2D network for 2. Magnetic susceptibility measurements over the 2-300 K range reveal very weak ferromagnetic interaction between the two Cu(II) ions in 1 and antiferromagnetic interaction in 2 mediated by nicotinate ligand, with J value to be 0.15 and −0.19 cm⁻¹, respectively.     

Seven-coordinate Mn(II) and Co(II) complexes of the pentadentate ligand 2,6-diacetyl-4-carboxymethyl-pyridine bis(benzoylhydrazone): Synthesis, crystal structure and magnetic properties

The metal complexation properties of a functionalized N₃O₂ donor ligand H₂L², where H₂L² stands for 2,6-diacetyl-4-carboxymethyl-pyridine bis(benzoylhydrazone), are investigated by structural and spectroscopic (IR, ESI-MS and EPR) characterization of its Mn(II) and Co(II) complexes. The ligand H₂L² is observed to react essentially in the same fashion as its unmodified parent H₂L¹ producing mixed-ligand [M(H₂L²)(Cl₂)] complexes (M = Mn^II (1), Co^II (3)) upon treatment with MCl₂. Complexes [M(HL²)(H₂O)(EtOH)]BPh₄ (M = Mn 2, M = Co 4), incorporating the supporting ligand in the partially deprotonated form (HL²)⁻, are formed by salt elimination of the [M(H₂L²)(Cl₂)] compounds with NaBPh₄. Compounds 2 and 4 are isostructural featuring distorted pentagonal-bipyramidal coordinated Mn^II and Co^II ions, with the H₂O and EtOH ligands bound in axial positions. Intermolecular hydrogen bonding interactions of the type M-OH₂?O-M involving the H₂O ligands and the carbonyl functions of the supporting ligand assembles the complexes into dimers. Temperature-dependent magnetic susceptibility measurements (2-300 K) show a substantially paramagnetic Curie behavior for the Mn²⁺ compound (2) influenced by zero-field splitting and significant orbital angular momentum contribution for 4 (high-spin Co^II). The exchange coupling across the Mn^II-OH₂?O-Mn^II bridges in 2 was found to be less than 0.1 cm⁻¹, suggesting that no significant intradimer exchange coupling occurs via this path.     

Two new supermolecular structures of organic-inorganic hybrid compounds: [Zn(phen)(SO4)(H2O)2]n and [Cu(phen)(H2O)2] · SO4 (phen = 1,10-phenanthroline)

Two new organic-inorganic hybrid compounds [Zn(phen)(SO₄)(H₂O)₂]_n (1) and [Cu(phen)(H₂O)₂] · SO₄ (2) have been prepared by conventional aqueous solution synthesis and characterized by single-crystal X-ray diffraction, IR spectroscopy, thermal gravimetric analysis (TGA) and fluorescent spectroscopy. In compound 1, the sulfate group adopts bidentate mode to coordinate with two Zn(II) ions to form one-dimensional polymer. The one-dimensional polymers are further linked together via the intermolecular hydrogen-bonding and π-π stacking interactions to form a 3D supramolecular framework. Compound 2 is build up of discrete [Cu(phen)(H₂O]²⁺ cations and SO₄²⁻ anions to form a three-dimensional framework via hydrogen-bonding and π-π stacking interactions. Furthermore, the luminescent properties of both 1 and 2 were studied. The complexes 1 and 2 excited at 280 nm wavelength produced characteristic luminescence features, arising maybe due to the π-π transitions.     

Assembly of two novel cadmium(II) supramolecular architectures constructed from pyridine-functionalized 1,10-phenanthroline ligand

Two novel cadmium(II) coordination polymers [Cd(pyip)(ox)]·H₂O (1) and [Cd₂(pyip)₂(ox)₂·(H₂O)][Cd(pyip)(ox)]·4(H₂O) (2) (pyip = 2-(pyridin-3-yl-1H-imidazo [4,5-f][1,10]phenanthroline, H₂ox = oxalic acid), have been hydrothermal synthesized and characterized by single crystal X-ray diffraction. Compound 1 is 1D zigzag chain, in which oxalate anion as bridging ligand is responsible for the formation of the main framework and pyip as chelating ligand grafts on two sides of the zigzag chain. Compound 2 contains two kinds of independent polymers [Cd₂(pyip)₂(ox)₂(H₂O)] (A) and [Cd(pyip)(ox)] (B) to form an interdigitated 1D + 1D structure, in which polymers A and B are paratactically assembled in an ABCD sequence. The fundamental unit of polymer B in 2 is the same as that in 1. For compounds 1-2, weak interactions, primarily hydrogen bonding and π?π stacking interactions, have greatly influence on the supramolecular motifs recognized in the crystal packing. Especially, the oxalate anions as bridging ligand simultaneously adopt multiform coordination modes in two compounds. In addition, 1 and 2 displayed a strong fluorescent emission in the solid state at room temperature.     

Cd(II)-NCS/NCO complexes of 1-alkyl-2-(arylazo)imidazole: Single crystal X-ray structure of [Cd(HaaiMe)2(SCN)2]

The reaction of Cd(OAc)₂ · 4H₂O and 1-alkyl-2-(arylazo)imidazole [RaaiR′ where R = H (a), Me (b); R′ = Me (1/3/5), Et (2/4/6)] and NH₄NCS/NaNCO in methanol in 1:2:2 mole ratio has afforded [Cd(RaaiR′)₂(NCS)₂] (3, 4) and [Cd(RaaiR′)₂(NCO)₂] (5, 6) complexes. The complexes are characterized by different physicochemical methods and in one case, the structure was confirmed by single crystal X-ray diffraction study for title compounds.     

Molecular interactions of zinc(II) cyclams with polycarboxylato ligands

Four new zinc(II) cyclams of the composition {Zn(L)(tp²⁻) · H₂O}_n (1), {Zn(L)(H₂bta²⁻) · 2H₂O}_n (2), [Zn₂(L)₂(ox²⁻)] 2ClO₄ · 2DMF (3), and Zn(L)(H₂btc⁻)₂ · 2DMF (4), where L = cyclam, tp²⁻ = 1,4-benzenedicarboxylate ion, H₂bta²⁻ = 1,2,4,5-benzenetetracarboxylate ion, ox²⁻ = oxalate ion, DMF = N,N-dimethylformamide, and H₂btc⁻ = 1,3,5-benzenetricarboxylate ion, have been synthesized and structurally characterized by a combination of analytical, spectroscopic and crystallographic methods. The carboxylato ligands in the complexes 1-4 show strong coordination tendencies toward zinc(II) cyclams with hydrogen bonding interactions between the pre-organized N-H groups of the macrocycle and oxygen atoms of the carboxylato ligands. The macrocycles in 1, 2, and 4 adopt trans-III configurations with the appropriate R,R,S,S arrangement of the four chiral nitrogen centers, respectively. However, the complex 3 shows an unusual cis V conformation with the R,R,R,R nitrogen configuration. The finding of strong interactions between the carboxylato ligands and the zinc(II) ions may provide additional knowledge for the improved design of receptor-targeted zinc(II) cyclams in anti-HIV agents.     

Synthesis, crystal structures, and fluorescence properties of six complexes with thiophene derivative carboxylic acid ligand

The crystallization of 2,3-dihydro-thieno[3,4-b][1,4] dioxine-5,7-dicarboxylic acid (H₂tddc) with divalent transitional metal (Co, Ni, Zn, Cd) or with tervalent lanthanide metal (Sm) and with mixed ligand 4,4′-bipyridine (4,4′-bipy) or 1,10-phenanthroline (1,10-phen) formed six new complexes: [Co(C₈H₄O₆S) · 3H₂O] (1), [Co(C₈H₄O₆)(1,10-phen)(H₂O)] · H₂O (2), [Ni(C₈H₄O₆S)(4,4′-bipy)(H₂O)] · 3H₂O (3) [Sm(C₈H₄O₆S)(NO₃)(H₂O)₄] · 2H₂O (4), [Zn(C₈H₄O₆S)(H₂O)₃] (5), and [Cd₂(C₈H₄O₆S)₂(4,4′-bipy)₂] (6). The structures of these six crystals have been characterized by single-crystal X-ray diffraction analyses, which revealed that complexes 1, 4, 5 are all one-dimensional chain structures and they self-assemble into three-dimensional super-molecules via the hydrogen bond interactions and π-π stacking interactions, 2 is also a one-dimensional chain structure but still self-assembles into one-dimensional double-chains, the complex 3 has two-dimensional undulating parallelogram grid structure extended along the bc-plane, the crystal of 6 is a 3D threefold interpenetration topology framework with 4⁶6³8 nodes. The photoluminescent properties of the H₂tddc ligand and the six compounds have been measured in the solid state at room temperature. Free ligand has no luminescence, while its complexes 1, 4, and 6 all exhibit intense photoluminescence which implies that these complexes may be excellent candidates for potential photoactive materials.     

Synthesis, spectroscopic and magnetostructural evidence for the formation of Cu(II) complexes of pyridyl-2-carboxylate (2-pca) and quinolyl-2-carboxylate (2-qca) as a result of a novel oxidative P-dealkylation reaction of diethyl 2-pyridylmethylphosphonate (2-pmpe) and diethyl 2-quinolylmethylphosphonate (2-qmpe) ligands

The interaction of diethyl 2-pyridylmethylphosphonate (2-pmpe) ligand with CuX₂ salts unexpectedly leads to the formation of compounds of the formula Cu(2-pca)₂ [X=Cl⁻ (1), CH₃COO⁻ (3)], and Cu(2-pca)Cl [X=Cl⁻ (2)] (2-pca=pyridine-2-carboxylate ion). The diethyl 2-quinolylmethylphosphonate ligand (2-qmpe) reacts with CuX₂ salts to similarly yield compounds of stoichiometry Cu(2-qca)₂ · H₂O (X=ClO₄ ⁻ (4)], and for X=Cl Cu(2-qca)₂ · H₂O (5) and Cu(2-qca)Cl (6), (2-qca=quinoline-2-carboxylate ion). These compounds are products of a novel oxidative P-dealkylation reaction, which takes place on 2-pmpe and 2-qmpe ligands under the used conditions. The compounds were characterized by infrared, ligand field, EPR spectroscopy and magnetic studies. Cu(2-pca)₂ exists in two crystalline forms, a blue form (1) and a violet form (3). For 3 the single-crystal structure was determined. The copper atom is four-coordinated in a square-planar geometry. The stack between related (and hence parallel) pca moieties involves interatomic distances of 3.27 Å. Cu(2-qca)₂ · H₂O also exists in two forms, a green (4) and a blue-green (5). Both these complexes are five coordinated, involve the same CuN₂O₃ chromophore and are examples of the distortion isomers. Variable-temperature magnetic susceptibility measurements (1.9-300 K) have shown that the antiferromagnetic coupling observed is much stronger in 6 than in 1, 3, 4 and 5. For 2 a ferromagnetic exchange occurs.     

Spectral properties and bio-activity of copper(II) clofibriates, part III: crystal structure of Cu(clofibriate)2(2-pyridylmethanol)2, Cu(clofibriate)2(4-pyridylmethanol)2(H2O) dihydrate, and Cu2(clofibriate)4(N,N-diethylnicotinamide)2

New copper(II) clofibriates (clof, {2-(4-chlorophenoxy)-2-methylpropionic or 2-(4-chlorophenoxy)isobutyric acid}) of composition Cu(clof)₂L₂ (where L=2-pyridylmethanol (2-pymeth) (1), N-methylnicotinamide (Menia) (4), N,N-diethylnicotinamide (Et₂nia) (5), isonicotinamide (isonia) (7) or methyl-3-pyridylcarbamate (mpc) (8)), [Cu(clof)₂(4-pymeth)₂(H₂O)] · 2H₂O (4-pymeth=4-pyridylmethanol) (2 · 2H₂O) and Cu(clof)₂L (where L=4-pymeth (3) or Et₂nia (6)) have been prepared and spectroscopically characterized. All the Cu(clof)₂L₂ compounds seem to possess distorted octahedral copper(II) stereochemistry with differing tetragonal distortions. An X-ray analysis of 1 was carried out and it featured a tetragonal-bipyramidal geometry around the copper(II) atom. X-ray analysis of 2 · 2H₂O featured a square-pyramidal geometry around copper(II) atom. Both the Cu(clof)₂L compounds seem to consist of a binuclear unit of tetracarboxylate type bridging. An X-ray analysis of 6 revealed typical binuclear paddle-wheel type structure, consisting of two copper(II) atoms in square-pyramidal geometry bridged by four carboxylate anions in the xy-plane. All complexes under study were characterized by EPR and electronic spectroscopy. The antimicrobial effects have been tested on various strains of bacteria, yeasts and filamentous fungi.