Phthalate Complexes Research Articles

Chemically Reversible Translational Moiré Superlattice Formations in the Two-Dimensional Films of the Zinc Phthalate Complex.

The exciting electronic properties of two-dimensional layered materials introduced by twist angle and lattice mismatch between two consecutive layers are well-recognized. The major challenge lies in the control over the moiré periodicity. Herein, we report a chemically directed way to achieve the desired precision over moiré periodicity of the assembly of a complex of zinc ions and o-phthalic acid utilizing soft bonds. The reaction of o-phthalic acid with zinc ions in the aqueous medium at 80 °C for 1 h followed by preserving the reaction mixture at ambient temperature (35 °C) resulted in translational moiré superlattices with precise periods. Those lattices are further stacked angularly to give rotational super-moiré lattices. Further, the role of the π-zinc ion interaction in the origin of moiré fringes was examined with the reaction with 8-hydroxyquinoline-5-sulfonic acid (HQS) that also established the reversible nature of the superlattices. The present observations also suggest the formation of moiré superlattice through ion insertion in a chemical lattice.

Chain, Network and Framework Formation in Uranyl Ion Complexes with 1,1′‐Biphenyl‐3,3′,4,4′‐Tetracarboxylate

Abstract1,1′‐Biphenyl‐3,3′,4,4′‐tetracarboxylic acid dianhydride has been reacted with uranyl nitrate under solvo‐hydrothermal conditions and in the presence of different counterions to give three complexes of varying periodicity. [Co(en)3]‐ [UO2(bptc)(HCOO)] ⋅ 2.5H2O (1) crystallizes as a monoperiodic coordination polymer in which the bptc4− ligand is exclusively bound through formation of two 7‐membered chelate rings. The [Co(en)3]3+ counterion is essentially a hydrogen bond donor, forming 15 hydrogen bonds with carboxylate and water oxygen atoms. In [H2NMe2]2[UO2(bptc)] ⋅ 0.5H2O (2), half the ligand forms a 7‐membered chelate ring, and the other half bridges two uranium atoms, resulting in the formation of a diperiodic network with hcb topology, the H2NMe2+ counterions being located between the undulating sheets. [PPh4]4[(UO2)4(bptc)3] ⋅ 6H2O (3) contains a mixture of ligands forming either four 4‐membered or two 7‐membered chelate rings, the latter with further bridging, which gives a triperiodic framework displaying large channels, each of which contains two rows of PPh4+ counterions. These results are compared to those of previous studies with this ligand, and of similar studies of phthalate complexes of uranyl ion, in particular in relation to 7‐membered chelate ring formation.

Influence of hydration/dehydration on adsorbed molecules: Case of phthalate on goethite

The behavior of adsorbed species on metal (hydr)oxides under water unsaturated conditions has been seldom studied despite its major implications in several domains such as geochemistry and heterogeneous catalysis. In this study, chemical forms of phthalate adsorbed on iron hydroxide (goethite) were investigated by infrared spectroscopy upon hydration and dehydration of goethite particle aggregates. Experimental results indicated important changes with relative humidity (RH) on chemical forms of phthalates adsorbed on goethite. With increasing RH from the dried state, bidentate phthalate surface complex is partially desorbed to form a protonated monodentate phthalate complex by using protons from water molecules. This protonated monodentate phthalate is still kept adsorbed on the goethite surface but becomes deprotonated at high RH values by solvating in liquid-like water covering on the goethite surface. DFT calculations made on a simplified system support these adsorption models. These results indicate that further studies are needed on the behavior of adsorbate in water unsaturated systems including hydration/dehydration processes.

Unusual Mn5 cluster with a ‘twisted bow-tie’ topology and MnIIMnIII2MnIV2 oxidation states: Synthesis, structure, and magnetic properties

The ‘reductive aggregation’ procedure involving the reaction of MnO4- in MeOH in the presence of a carboxylic acid has been extended for the first time to the use of a dicarboxylic acid and the additional presence of a chelate, namely phthalic acid (phthH2) and 2,2′-bipyridine (bpy), respectively. The MnO4-:phthH2:bpy = 1:2:1 reaction in MeOH has led to isolation of [Mn5O4(phth)3(phthH)(bpy)4](phthH2)(phthH) (1), whose Mn5 cation possesses a ‘twisted bow-tie’ topology comprising two near-perpendicular MnII,III,IV3 scalene triangles fused at the MnII ion. Each triangle is bridged by a central μ3-O2- and a μ2-O2- on the MnIIIMnIV edge. Peripheral ligation is provided by the phthalate groups bridging in various modes, and a chelating bpy on each MnIII and MnIV ion. The cation is a rare example of a cluster with three Mn oxidation states, and it is also the first MnIV-containing phthalate complex. Fitting of variable-temperature, solid-state dc magnetic susceptibility data collected in a 0.1 T field in the 5.0–300 K range gave J1 = J(MnIIIMnIV) = − 116(3) cm−1, J2 = J(MnIIMnIV) = − 6.0(4) cm−1, J3 = J(MnIIMnIII) = +3.8(8) cm−1, and g = 1.95, with TIP = 500 × 10-6 cm3 mol−1. These indicate an S = 7/2 spin ground state, which was confirmed by a fit of magnetization data collected in the 0.1–7.0 T and 1.8–10.0 K ranges, and by ac in-phase susceptibility data in zero dc field and a 3.5 G ac field at a 1000 Hz frequency.

Mechanism of phthalic acid collector in flotation separation of fluorite and rare earth

The mechanism of phthalic acid, a dicarboxylic acid collector, in flotation separation of fluorite and rare earth (RE) was studied in this paper. The experimental data of flotation show that phthalic acid, as the collector, can realize highly efficient separation of fluorite and rare earth under weakly acidic conditions. The adsorption mechanism of phthalic acid on the surface of fluorite and bastnaesite was analyzed in this paper by means of the zeta potential measurement, the Fourier transform infrared (FT-IR), the X-ray photoelectron spectroscopy (XPS) and the stability constant measurement of active metal ion and phthalic acid coordination complex. According to the zeta potential testing results, the surfaces of fluorite adsorb the collector phthalate ion with negative charge under weakly acidic conditions which, in turn, increases its electronegativity and results in the motion of its potential. After the reaction between phthalic acid and fluorite ores under weakly acidic conditions, the peak of the fluorite ores is found to have significant changes in the FT-IR results, indicating strong chemical adsorption on the surfaces of phthalic acid and fluorite ores. According to the XPS analysis, the peak of benzene ring of phthalic acid is as high as 2% on the surface of fluorite, while no obvious characteristic peak of benzene ring is found on the surface of bastnaesite. According to the pH potentiometric titration results, the stability constant Ktotal of calcium phthalate complex within the acid range is higher than the stability constant Ktotal' of cerium phthalate complex, indicating that the complex generated between phthalic acid and Ca2+ is more stable than the complex generated between phthalic acid and Ce3+. The possible reason is that Ca2+, with the highest reticular density, plays a prevailing role in the octahedron structure of fluorite amidst the acidic media. As the active point of flotation, Ca2+ works with the carboxyl groups of the collector phthalic acid (–C=O–) to form polycyclic calcium phthalate complex.

Morphology Control in AgCu Nanoalloy Synthesis by Molecular Cu(I) Precursors.

As nanoparticle preparation methods employing bottom-up procedures rely on the use of molecular precursors, the chemical composition and bonding of these precursors have a decisive effect on nanoparticle formation and their resulting morphology and properties. We synthesized the Cu(I) complexes [Cu(PPh3)2(bea)] (1, bea = benzoate) and [Cu(PPh3)3(Hphta)] (2, phta = phthalate) by reducing the corresponding Cu(II) mono- and dicarboxylates with triphenylphosphine. We characterized 1 and 2 by single-crystal X-ray diffraction analysis, elemental analyses, infrared and nuclear magnetic resonance spectroscopy, and mass spectrometry and obtained complete information about their structures in the solid state and in solution. Also, we examined their thermal stability in oleylamine and determined their decomposition temperatures to be used as the minimal reaction temperature in metal nanoparticle synthesis. The complexes 1 and 2 differ in the number of reducing PPh3 ligands and the strength of carboxylate bonding to the Cu(I) center. Therefore, we employed them in combination with [Ag(NH2C12H25)2]NO3 as molecular precursors in the solvothermal hot injection synthesis of AgCu nanoalloys in oleylamine and demonstrated their influence on the elemental distribution, phase composition, particle size distribution, shape, morphology, and optical properties of the resulting nanoparticles. The nanoalloy particles from the benzoate complex 1 were oblate and polydisperse and exhibited two surface plasmons at 393 and 569 nm, which is caused by their Janus-type structure. The nanoparticles prepared from the phthalate complex 2 were round and monodisperse and exhibited one plasmon at 413 nm, as they formed an AgCu solid solution with a random distribution of the elements in a particle.

A supramolecular dimer of two crystallographically independent Co(II) phthalate bipyridine complexes in one single crystal: Synthesis, crystal structure, and thermal studies

A cobalt(II) complex with 2,2'-bipyridine and phthalate ligands of the composition [Co(bpy)(Hpht)(H2O)3][Co(bpy)(pht)(H2O)2]Cl·2H2O (bpy: 2,2'-bipyridine; Hpht, pht: o-phtha­late anions) are synthesized and characterized by FT-IR and electronic spectroscopy and single crystal X-ray diffraction. The compound crystallizes in the triclinic system, space group, Z = 2 with a = 11.998(5), b = 13.956(5), c = 14.313(5) Å, α = 112.33(5), β = 95.067(5), γ = 109.166(5)°. The structure consists of a cationic complex unit [Co(bpy)(Hpht)(H2O)3]+, a neutral complex unit [Co(bpy)(pht)(H2O)2], a chloride anion, and two lattice water molecules. The intermolecular O—H⋯O hydrogen bond links two independent Co(II) complexes in the crystal structure, forming a supramolecular dimer. The dimers in the crystal form a 2D layered network structure via weak supramolecular π—π stacking, C—H⋯O, C—H⋯Cl, and O—H⋯Cl hydrogen bonding interactions. The thermal behavior of the compound is investigated.

Targeting protein kinase and DNA molecules by diimine–phthalate complexes in antiproliferative activity

The serendipitous discovery of the anticancer drug cisplatin cemented medicinal inorganic chemistry as an independent discipline in 1960s. DNA and protein kinases are one of the major intracellular targets of many anticancer drugs. It is thus highly desirable to develop metal complexes, either by interacting with DNA or to target alternative cellular machinery such as protein kinases to provide a more effective means of monitoring disease progression. In this study we report the synthesis and characterization of few novel Cu(II) and Zn(II) Knoevenagel condensed metallointercalators incorporating phthalic acid. The intercalation behavior of the complexes with DNA is confirmed by spectral and analytical experiments. Due to the promising performance of DNA interaction efficacy of Cu(II) complexes 1–4, their in vitro and in vivo anticancer properties are explored on various cancerous cell lines which reveal that they exhibit substantial anticancer activity without affecting the normal cells. It is found that the complex 1 induces apoptosis in Hep G2 cells. Theoretically, DFT is used to optimize the Cu(II) complexes 1–4 to explore their quantum mechanical properties and to carry out affinity studies against cyclin dependant kinase 2 (CDK2) to understand atomic level interactions. Further, the complex–receptor stability is confirmed by molecular dynamics.

Growth and characterization of hexaaquacobalt(II) dipotassium tetrahydrogen tetra-o-phthalate tetrahydrate crystals

Single crystals of hexaaquacobalt(II) dipotassium tetrahydrogen tetra-o-phthalate tetrahydrate K2[Co(H2O)6](C8H5O4)4·4H2O (PCHP), a semiorganic light-rose colored crystal of size ∼38 × 16 × 4 mm3 have been grown by slow evaporation solution growth technique. The lattice parameters of the as-grown crystals were obtained by single crystal X-ray diffraction analysis. The functional groups of the phthalate complex were confirmed by Fourier transform infrared spectroscopy analysis. The UV–Vis optical absorption spectrum of PCHP shows the lower optical cut-off at ∼300 nm and the crystal was transparent in the visible region. The structural perfection of the grown crystal has been analyzed by high-resolution X-ray diffraction (HRXRD) rocking curves (DC). The DC contains multi-peaks showing the structural grain boundaries. The dielectric, thermal and mechanical behaviors of the specimen were also studied.

Series of Mixed Uranyl–Lanthanide (Ce, Nd) Organic Coordination Polymers with Aromatic Polycarboxylates Linkers

Three series of mixed uranyl-lanthanide (Ce or Nd) carboxylate coordination polymers have been successfully synthesized by means of a hydrothermal route using either conventional or microwave heating methods. These compounds have been prepared from mixtures of uranyl nitrate, lanthanide nitrate together with phthalic acid (1,2), pyromellitic acid (3,4), or mellitic acid (5,6) in aqueous solution. The X-ray diffraction (XRD) single-crystal revealed that the phthalate complex (UO(2))(4)O(2)Ln(H(2)O)(7)(1,2-bdc)(4)·NH(4)·xH(2)O (Ln = Ce(1), Nd(2); x = 1 for 1, x = 0 for 2), is based on the connection of tetranuclear uranyl-centered building blocks linked to discrete monomeric units LnO(2)(H(2)O)(7) via the organic species to generate infinite chains, intercalated by free ammonium cations. The pyromellitate phase (UO(2))(3)Ln(2)(H(2)O)(12)(btec)(3)·5H(2)O (Ce(3), Nd(4)) contains layers of monomeric uranyl-centered hexagonal and pentagonal bipyramids linked via the carboxylate arms of the organic molecules. The three-dimensionality of the structure is ensured by the connection of remaining free carboxylate groups with isolated monomeric units LnO(2)(H(2)O)(7). The network of the third series (UO(2))(2)(OH)Ln(H(2)O)(7)(mel)·5H(2)O (Ce(5), Nd(6)) is built up from dinuclear uranyl units forming layers through connection with the mellitate ligands, which are further linked to each other through discrete monomers LnO(3)(H(2)O)(6). The thermal decomposition of the various coordination complexes led to the formation of mixed uranium-lanthanide oxide, with the fluorite-type structure at 1500 °C (for 1, 2) or 1400 °C for 3-6. Expected U/Ln ratio from the crystal structures were observed for compounds 1-6.

Luminescent micro- and nanofibers based on novel europium phthalate complex

We synthesized by wet chemical route a novel europium–potassium phthalate complex Eu3+K+[(COO)2(C6H4)]2. The compound is a white powder insoluble in water. X-ray diffraction evaluation shows that we obtained a new crystalline compound with no traces of the starting materials (potassium hydrogen phthalate and europium chloride). Scanning electron microscopy reveals that the powder consists of fiber-shaped structures with sizes larger than 250 nm in diameter. Energy dispersive X-ray analysis proves that the compound has a 1:1 europium–potassium ratio. Fourier transform infrared spectroscopy confirms the presence of the phthalate in the new compound. Photoluminescence and cathodoluminescence measurements show that the fiber-shaped structures are intensely luminescent with emission bands corresponding to the 5D0→7FJ (J = 1–4) Eu (III) ion’s transitions in the region between 580 nm and 700 nm, the most intense maximum being observed around 615 nm. Up-converted luminescence with a maximum at 315 nm was recorded.

Bis-phenanthroline copper(ii) phthalate complexes are potent in vitro antitumour agents with ‘self-activating’ metallo-nuclease and DNA binding properties

Three, structurally characterised, bis-phen Cu(II) complexes of the phthalate isomers display rapid, low micromolar in vitro cytotoxicity against a range of epithelial tumour cells. The complexes induce relaxation of supercoiled plasmid DNA in the absence of external reducing agents and display efficient CT-DNA, Poly[d(A-T)](2) and Poly[d(G-C)](2) binding.

Synthesis, structures and biological properties of nickel(II) phthalates with imidazole and its derivatives

Four new nickel(II) phthalate compounds: mononuclear complexes [Ni(Im)] 6(Pht)·H 2O ( 1), [Ni(Pht)(Im) 3(H 2O) 2]·H 2O ( 2) and [Ni(Pht)(2-MeIm) 3(H 2O) 3]·H 2O ( 3), and coordination polymer [Ni(Pht)(4-MeIm) 2(H 2O)] n ( 4) (where Pht = dianion of o-phthalic acid, Im = imidazole, 2-MeIm = 2-methylimidazole, 4-MeIm = 4-methylimidazole) have been synthesized. The complexes 1– 4 were characterised by elemental analysis, IR data, thermogravimetric, and X-ray diffraction analyses. X-ray analysis shows that the asymmetric unit of 1 consists of [Ni(Im)] 6 2+ cation, Pht 2− anion and solvate H 2O molecule. The phthalate dianion does not take part in coordination to metal ion. The cations, anions and water molecules are linked via N–H ⋯ O and O–H ⋯ O interactions forming 2D hydrogen-bonded networks. The structures of 2 and 3 are similar to other mononuclear Ni(II) phthalate complexes where Pht 2− anions act as monodentate ligands and uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen bonded double-chains. The structure of 4 consists of [Ni(4-MeIm) 2(H 2O)] building units connected by phthalate ions to form helical chains. The complexes 1– 4 were tested for their ability to increase the biosynthesis of enzymes.

Ternary complex formation of Eu(III) with o-phthalate in aqueous solutions

Ternary hydroxo complex formation of Eu(III) with o-phthalate was investigated by potentiometry and fluorescence spectrophotometry. Curves of the equilibrium pH versus the amount of NaOH added showed that the pH value starting to form a Eu(III) precipitate was decreased due to the formation of a ternary hydroxo complex, EuOHL(s) (L = phthalate). The formation of EuOHL(s) was qualitatively confirmed by the enhancement of the fluorescence intensity of Eu(III) in the precipitate with the light absorbed by phthalate, and was quantitatively confirmed by the measurement of the amounts of Eu(III), OH − and phthalate included in the precipitate. The solubility product of EuOHL(s) was determined as p K sp 0 = 15.6 ± 0.4 . Characteristic features in the fluorescence spectra and the solubility product of the Eu(III)–phthalate complex were compared with those of the Eu(III)–PDA (PDA = pyridine-2,6-dicarboxylate) complex. The fluorescence intensity of the EuL + complex of L = PDA was about 11 times stronger than that of L = phthalate. The origin of the difference in the fluorescence intensity is discussed based on the intramolecular energy transfer effect from the lowest triplet energy level of the ligand to the resonance energy level of Eu(III).

Oxidation of anethole with hydrogen peroxide catalyzed by oxovanadium aromatic carboxylate complexes

Abstract Selective oxidation of anethole with hydrogen peroxide to anisaldehyde has been developed using a novel efficient catalytic process by oxovanadium complexes bearing aromatic carboxylate ligands such as phthalate, salicylate and benzoate. Under mild reaction conditions (4 h at 303 K), oxovanadium(IV) phthalate complex (OPC) (IV) provided the best results with 100% conversion of anethole and 73.5% selectivity for anisaldehyde at low catalyst loading (∼0.5 mol%). Inspiringly, H 2 O 2 can be stoichiometrically used (H 2 O 2 :anethole = 2:1) for the complete conversion.

Synthesis and crystal structure of catena-bis(nicotinamide)aqua(μ-phthalato)copper(II) hemihydrate

The copper(II) phthalate complex with nicotinamide [CuL2(μ-Pht)(H2O)] · 0.5H2O(I) (where L is nicotinamide and Pht2− is an anion of phthalic acid) is synthesized and investigated using IR spectroscopy and X-ray diffraction. The crystals of compound I are monoclinic, a = 13.368(2) A, b = 7.891(3) A, c = 20.480(2) A, β = 108.69(2)°, Z = 4, and space group P21/c. The structural units of crystal I are linear chains formed by bridging phthalate anions and crystallization water molecules. The copper atom is coordinated by two pyridine nitrogen atoms of two nicotinamide ligands (Cu-N, 2.001 and 2.045 A), two oxygen atoms of different phthalate anions (Cu-O, 1.964 and 2.235 A), and the oxygen atom of the H2 O molecule (Cu-O, 2.014 A). The coordination polyhedron of the copper atom is completed to an elongated (4 + 1 + 1) tetragonal bipyramid by the second (chelating) oxygen atom of the carboxyl group (Cu-O, 2.587 A), which is one of the anions of phthalic acid. The linear polymer molecules are joined into complex macromolecular dimers with the closest internal contacts of the specific type. The macromolecular dimers are the main supramolecular ensembles of the crystal structure.

Structures and stabilities of Cd(II) and Cd(II)-phthalate complexes at the goethite/water interface

The complexation of Cd(II) and Cd(II)-phthalate at the goethite/water interface were investigated by EXAFS and IR spectroscopy, by batch adsorption experiments and by potentiometric titrations at 298.15 K. The EXAFS spectra showed Cd(II) to form only inner-sphere corner-sharing complexes with the goethite surface sites in the presence and absence of phthalate. EXAFS spectra also showed the presence of Cd(II)-chloride complexes in 0.1 mol/L NaCl. IR spectra also showed phthalate to form (1) an inner-sphere complex with adsorbed corner-sharing Cd(II) surface complexes in the pH 3.5 to 9.5 and (2) an outer-sphere complex with the same type of corner-sharing Cd(II) complex however at pH > 6, in addition to the inner- and outer-sphere complexes of phthalate reported in a previous study. The potentiometric titration and the batch adsorption data were used to constrain the formation constants of the different Cd(II)-phthalate surface complexes on the dominant {110} and the {001} planes of the goethite. The models were carried out with the Charge Distribution Multisite Complexation model coupled to the Three Plane Model and can predict the molecular-scale speciation of cadmium and phthalate in the presence of goethite. Cd(II) adsorption models calibrated on a 90 m 2/g goethite also could accurately predict experimental data for a 37 m 2/g goethite of slightly different basic charging properties.

Application of complex esters in poly(vinyl chloride) plastisols and plasticats

PurposeTo evaluate the efficiency of complex esters as plasticizers in polyvinyl chloride plastisols and plasticates.Design/methodology/approachSeveral poly(vinyl chloride) plastisols and plasticates were prepared with standard phthalate plasticizers and complex esters and were characterised using standard and laboratory methods.FindingsThe use of mixtures of three new CE with standard phthalate plasticizers increased the physical, mechanical and electric characteristics of the resulting PVCPs and PVCPl.Research limitations/implicationsThe use of three new CE, obtained by esterification of dicarboxylic acids (adipic, sebacic, pelargonic), poly(ethylene glycol) and i‐octanole, as plasticizers of poly(vinyl chloride) plastisols and plasticates was investigated. The use of CE based on other organic acids could be explored.Practical implicationsThe results confirmed the efficiency of plasticization of PVC by CE. Such a finding has significant industrial implication.Originality/valueSeveral findings are original and are of importance to relevant industry. The new CE with high molecular weights were effective plasticizers of PVC. The efficiency of the plasticizers depended on their chemical structure. The molecular weight of the CE had no influence on the compatibility of plasticizers and other components of the PVC plastisols and plasticates.

Selective recognition of configurational substates of zinc cyclam by carboxylates: implications for the design and mechanism of action of anti-HIV agents.

The interaction of metal cyclams with carboxylate groups is thought to play an important role in their binding to the CXCR4 chemokine receptor and in their anti-HIV activity. Here we report the synthesis of acetate, phthalate, perchlorate and chloride complexes of Zn(II) cyclam (1,4,8,11-tetraazacyclotetradecane). The X-ray crystal structures of [Zn(cyclam)(phthalate)](n)(CH(3)OH)(2n) and [Zn(cyclam)(H(2)O)(2)](OAc)(2) contain octahedral Zn(II) centres. Phthalate acts as a bridging ligand in the former complex, binding through monodentate carboxylate groups, and giving rise to infinite chains in the lattice together with extensive hydrogen bonding between carboxylate donor oxygen atoms and amine and methanol acceptor atoms. The uncoordinated acetate groups and the aqua ligand in the acetate complex are also involved in a rich network of hydrogen bonds and this may account for the unusually long Zn[bond]O distance (2.27 A). In both crystalline complexes, the macrocycle adopts the trans-III (S,S,R,R) configuration. 1D (1)H NMR spectra of all four complexes have been fully assigned by a combination of 2D [(1)H, (1)H] COSY and TOCSY, and [(1)H, (13)C] and [(1 )H, (15)N] HSQC NMR data. In aqueous solution, the stable trans-III configuration found in the solid-state equilibrates slowly (hours at 298 K) with trans-I (R,S,R,S) and cis-V (R,R,R,R) configurations. The trans-III configuration is predominant in aqueous solution for both the chloride and perchlorate complexes, but for the acetate and phthalate complexes, the cis-V configuration dominates. Carboxylate groups appear to stabilize the cis-V configuration in solution through Zn(II) coordination and hydrogen bonding. Titration of the chloride Zn(II)-cyclam complex with acetate confirmed that carboxylates strongly induce formation of the cis-V configuration. This implies that carboxylates can exert a strong influence over configurational selectivity. Cyclam NH hydrogen bonding is prevalent both in the solid state and in solution, and is relevant to the anti-HIV activity of Zn(II) and other metal cyclam complexes and to their ability to recognize the CXCR4 transmembrane co-receptor.

Thermal decomposition study of cobalt(II)-mixed ligand complexes with aliphatic or aromatic dicarboxylic acids and imidazole

The thermal decomposition study of Co(II)–malate, tartarate and phthalate complexes with imidazole was monitored by TG, DTG and DTA analysis in static atmosphere of air. The complexes and their calcination products were characterized by IR spectroscopy. The decomposition course and steps were analyzed and the kinetic parameters of the non-isothermal decomposition were calculated. The results revealed that the decomposition processes of these complexes are the best described by a random nucleation mechanism. The stability order found for these complexes follows the trend tartarate>phthalate>malate in terms of the dicarboxylic acid ligands.