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International audience; Three room-temperature metallomesogens based on Zn(II) cations pentacoordinated by different chelating N^N^N terpyridines and two monodentate gallate co-ligands were designed and synthesized. Depending on the terpyridine ligand's tip functionality, the complexes self-assemble into either a 3D hexagonal mesophase or into a columnar hexagonal mesophase. A systematic study between the structure (molecular architecture, arrangement of the molecules and columns, and chains in both types of mesophases) and photophysical properties (emission maxima and yields, lifetimes of the excited states in the mesophase), correlated with investigations of single molecules in solution, was conducted. Remarkably, one complex exhibited a record quantum yield of 95.0% in solution, while in the mesophase, despite quenching due to the radiative deactivation from the ILCT state, still retained a considerable emission yield of ϕ = 20.2%. The polarized emission of an oriented film, determined for the first time in columnar metallomesogens, shows a dichroic emission ratio (I||/I⊥) of 1.30. DFT and TDDFT computational studies confirmed the origin of the observed fluorescence anisotropy from the transition dipole moment oriented along the C2 symmetry axis of the molecule combined with a high level of order in the 3D mesophase.

Water pollution by synthetic organic dyes is mainly regarded as environmental and ecological issues worldwide and requires feasible solutions in face of the short-term risk to human health and stability of eco-systems. Therefore, in this paper, the magnetic mesoporous composites (MMC) were synthesized by surfactant template sol–gel method, using cetyl-trimethylammonium bromide (CTAB) as mesoporous structure generator and investigated for anionic and cationic dyes removal from aqueous solutions. The magnetic iron oxide nanoparticles were obtained by reverse co-precipitation, followed by mesoporous silica coating through modified sol–gel method. The obtained materials were characterized by FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy, Mossbauer spectroscopy, nitrogen adsorption, small-angle X-ray scattering and magnetization measurements. The influence of CTAB amount on the morpho-textural and structural properties of nanocomposites was studied. XRD and Mossbauer spectroscopy showed that the obtained nanocomposites were composed of pure maghemite nanoparticles, and TEM images revealed particles size around 10 nm, embedded in silica matrix. The combination of magnetic properties and high surface area values, up to 695 m2/g, made suitable the obtained nanocomposites to be used as adsorbents. The dye removal efficiency was higher than 90% after the first adsorption and remained above 65% after four adsorption–desorption cycles, indicating that the as-prepared magnetic mesoporous nanocomposites can be considered excellent adsorbent materials for the removal of both anionic and cationic dyes from wastewaters, and the recycling performance revealed the stability of MMC.

A series of homologous Schiff bases N,N′-bis[(4-decyloxy-salicylideneamino)-n-propyl]-piperazine] (ZOPPH2), and N,N′-bis[(4-dodecyloxy-benzylideneamino)-n-propyl]-piperazine (DBPP)(1), based on 1,4-bis(3-amino-propyl)-piperazine (APPZ), were designed and synthesized, with APPZ serving as the piperazine core, bilaterally flanked by extended alkyl chain-containing antennae. Driven by the pursuit of metallomesogenic materials bearing liquid crystalline state properties, chemical reactivity toward divalent metals Co(II) and Cu(II), in alcoholic or tetrahydrofuran/dimethylsulfoxide media, led to compounds [{Co(ZOPP)}(ClO4)]2.(CH3OH).2(CH3)2SO(2) and [Cu(APPZ)Cl]Cl(3). All materials were characterized by elemental analysis, spectroscopic techniques (UV–Visible, FT-IR, NMR where appropriate), molar conductivity, and X-ray crystallography. Physicochemical characterization emphasizes the a) importance of N,O-containing Schiff anchors in metal ion binding, b) significance of the phenolic moiety, on the flanks of the Schiff ligands, in promoting either metal ion complexation or dissociation of the Schiff base at the azomethine moiety junction, thereby altering metal ion chemical reactivity, and c) observed oxidation of Co(II) to Co(III) upon mononuclear complex formation. Hybrid DFT calculations on DBPP and ZOPPH2 suggest increased reactivity of the Schiff CH N moiety, in the absence of the phenolic moiety, and concurrent metal ion presence, thereby lending credence to the notion of metal-assisted rupture of the specific bond in DBPP and the emergence of specific metal-ligand product(s). Collectively, the data denote the significance of structural features of piperazine-core Schiff antennae ligands in a) promoting chemical reactivity toward transition metals, b) defining metal-ligand complexation and lattice architecture, and c) parameterizing such chemical reactivity into synthetic advances toward new materials with well-defined solid-state architecture, lattice and physicochemical properties.

Magnetic iron oxide-silica shell nanocomposites with different iron oxide/silica ratio were synthesized and structurally characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), small-angle neutron scattering, magnetic and N2-sorption studies. The composite that resulted with the best properties in terms of contact surface area and saturation of magnetization was selected for Pb2+ adsorption studies from aqueous media. The material presented good absorption capacity (maximum adsorption capacity 14.9 mg&middot, g&minus, 1) comparable with similar materials presented in literature. Its chemico-physical stability and adsorption capacity recommend the nanocomposite as a cheap adsorbent material for lead.

New heteroleptic complexes having the general formula (N^N)MQCl, where N^N = 2,2′-bipyridine or 1,10-phenanthroline, M = Cu(II) or Zn(II) and Q = quercetin were synthesized and characterized by analytical and spectroscopic methods. The complexes are more sensitive to air oxygen in solution or solid state than their flavonoid ligand. The increased sensitivity towards oxidation of the metal complexes was evidenced in the solid state by TGA-DTA measurements and in solution by UV–Vis absorption. The Zn(II) heteroleptic derivatives are luminescent in solution, their emission maxima being red-shifted with respect to quercetin precursor. The free radical scavenging activity of the complexes was evaluated using the stable DPPH radical. Cu(II) heteroleptic complexes have higher antioxidant activity than the Zn(II) complexes. Different oxidative mechanisms were evidenced for the Cu(II) and Zn(II) heteroleptic complexes.

Four new complexes, [Cu 9 L 6 ( µ 3 -ClO 4 ) 2 ](ClO 4 ) 4 ·4CHCl 3 1 , [Cu 3 L 2 (H 2 O) 2 ](ClO 4 ) 2 ·3H 2 O 2 , [Cu 6 L 4 (N 3 ) 2 ](ClO 4 ) 2 3 and [Cu 2 L(CH 3 COO) 2 ] 4 , where H 2 L stands for the Schiff base N , N ′-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine, were obtained and structurally characterized. Compounds 1 , 2 and 3 contain the Cu 3 L 2 2+ entities in which L 2− acts in an unsymmetrical mode with N 3 O donor set wrapped around marginal copper(II) and with the remained NO sets bound to the central copper ion. The marginal copper(II) ions are in distorted square pyramidal environment, whereas that of the central one is square planar. In 1 , the peripheral copper(II) ions (Cu1) are disposed linearly with a two-fold axis passing through the central Cu2 and with the Cu1⋯Cu2 and Cu2⋯Cu1′ distances of 6.755 A. The linear trinuclear units are bridged by a rare µ 3 -1,2,3 perchlorate ligand thus describing a 2D network. In [Cu 3 L 2 (H 2 O) 2 ](ClO 4 ) 2 ·3H 2 O, the Cu 3 L 2 2+ unit is capped by two water molecules. Here, due to the intramolecular hydrogen bonds, the metal ions are disposed in the corner of a triangle with the Cu1⋯Cu2, Cu1⋯Cu3 and Cu2⋯Cu3 distances of 5.976, 5.314 and 5.760 Ǻ, respectively. In [Cu 6 L 4 (N 3 ) 2 ](ClO 4 ) 2 , two Cu 3 L 2 2+ units are bridged by two azido groups thus forming a macrocycle of six copper(II) ions. In [Cu 2 L(CH 3 COO) 2 ], L 2− acts as a symmetrical binucleatig ligand through the two N 2 O sets disposed on each side of the piperazine ring and pointed away in opposite directions. The square pyramidal environment of copper is achieved by chelate acetato co-ligand.

A new synthetic approach for homo- and heteronuclear complexes, based on N,N′-bis[(3-methoxysalicylideneamino)-propyl]-piperazine (H2L) Schiff-base ligand, has been developed. The ligand has been crystallized in the form H2L·2DMSO and its structure has been solved. Using this ligand, the following complexes have been synthesized: [CoL](ClO4) (1), [Zn2L(CH3COO)2]·2H2O (2), [Cu3L2(NO3)2] (3) and [LaCu6L4(H2O)2(NO3)2](NO3)5·15H2O (4). The 1–4 complexes were characterized by elemental analysis, X-ray crystallography, infrared and diffuse reflectance spectroscopy. The crystallographic investigations revealed that H2L presents the stable chair conformation of the piperazine ring, while its coordination mode changes according to the nature of the metal ion and counterion, respectively, allowing the formation of mono- (1) and oligonuclear (2–4) complexes. Compound 1 consists of a mononuclear complex cation, where the double-deprotonated ligand (L2−) encapsulates the trivalent cobalt ion. In compound 2, L2− acts as a symmetrical binucleatig ligand through the two N2O sets disposed on each side of the piperazine ring and coordinates two zinc(II) ions. Compounds 3 and 4 contain trinuclear units where two ligand molecules coordinate unsymmetrically three CuII ions, with the N3O donor set wrapped around the peripheral CuII and the remaining NO sets bound to the central CuII ion. Two such trinuclear moieties coordinate the LaIII ion in crystal 4. Electrochemical behavior of compounds 1 and 3 and luminescent properties of compound 2 are discussed.

The influence of the counterions on the geometry of Cu(I) and Cu(II) unsubstituted phen-based (phen = 1,10-phenanthroline) complexes was investigated. The synthetic strategy used afforded the synthesis of both the tetracoordinated Cu(I) and pentacoordinated Cu(II) species with general formula [(phen)2Cu]+Y− (Y− = ClO4−, I−, SCN− and BF4−) and [(phen)2CuX]+Y− (X = Cl−, I−, NCS−, and Y− = ClO4−, I−, SCN− and BF4−), respectively. The firstly isolated Cu(I) complexes were characterized by IR, 1H NMR and UV-Vis spectroscopies, their proposed structures being confirmed by elemental analysis, atomic absorption spectroscopy (AAS) and thermogravimetric analysis (TGA). The molecular structure of Cu(II) complexes was determined by single crystal X-ray diffraction analysis. While for Cu(I) complexes, the coordinating nature of the counterions seems to have a strong influence (observed in the solid state and concentrated solution) on the flattening distortion (D2d → D2) of the geometry about the Cu(I) ion, in the Cu(II) derivatives, the size, shape, number and type of intermolecular interactions established by the counterions, drive not only the overall cations supramolecular organization, but also the molecular stereochemistry around the Cu(II) ion.

The behavior of 2-(2-hydroxy-benzylidene)-cyclohexan-1-one (BC) in the acidic and basic media was investigated. In acidic conditions a new dimeric structure 4′a-methoxy-2,2′,3,3′,4′,4′a,9′,9′a-octahydro-1H, 1′H-4,9′-bixanthene (XTC) was isolated. The structures of BC and XTC were confirmed by single crystal X-ray diffraction and NMR. In basic conditions, unprotonated specie (BC − ) was characterized by NMR, UV–Vis and fluorescent spectroscopy; BC could function as pH sensor.

International audience; Blue-green luminescent terpyridine-containing Pt II and Zn II complexes are reported. Equipped with lipophilic gallate units, which act as monodentate ancillary coordinating ligands and/or as anions, they display low-temperature mesomorphic properties (lamello-columnar and hexagonal mesophases for Pt II and Zn II complexes, respectively). The mesomorphic properties were investigated by polarised optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray scattering of bulk materials and oriented thin films. The model of self-assembly into the lamello-columnar phase of the Pt II complex has been described in detail. The optical properties of the complexes were investigated in the liquid and condensed liquid crystalline states, highlighting the delicate balance between the role of the metal in determining the type of excited state responsible for the emission, and the role of the ancillary ligand in driving intermolecular interactions for proper mesophase formation.

Three coordination polymers, 1∞[Cu3L2(NO3)]NO3·2MeOH·2H2O (1), 1∞[Cu3L2(N3)]CH3COO (2) and 1∞[Cu3L2(H2O)](ClO4)2 (3), based on the Schiff base H2L (H2L = N,N’-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine) have been synthesized and characterized. X-ray single-crystal analysis shows that compounds 1 and 2 are isostructural and crystallize in a non-centrosymmetric space group, P212121, while complex 3 crystallizes in a monoclinic system, space group P21/c. Compounds 1–3 consist of trinuclear complex entities, {Cu3L2}2+, connected via different bridges, nitrato (1), azido (2) and phenoxido (3), depending on the nature of the counterion. The cryomagnetic measurements reveal weak ferromagnetic interactions between the copper(II) ions bridged by the nitrato ligands in 1 (J = +1.026 cm−1, H = -JS1S2) and a weak antiferromagnetic coupling between the copper(II) ions connected by azido groups in 2 (J = -0.295 cm−1). The exchange interaction between the copper(II) ions connected by two phenoxido groups is antiferromagnetic, J = −12.780 cm−1.

A homoleptic ionic Cu(I) coordination complex that was based on 2,2&rsquo, biquinoline ligand functionalized with long alkyl chains (Cu(I)&ndash, C18) was used as a precursor to modify a carbon nanofiber paste electrode (Cu&ndash, C18/CNF). Randomized copper oxide microelectrode arrays dispersed within carbon nanofiber paste (CuOx/CNF) were obtained by electrochemical treatment of Cu&ndash, C18/CNF while using cyclic voltammetry (CV). The CuOx/CNF exhibited high electrocatalytic activity towards glucose oxidation at +0.6 V and +1.2 V vs. Ag/AgCl. Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) characterized the electrodes composition. Cyclic voltammetry (CV), square wave-voltammetry (SWV), and multiple-pulsed amperometry (MPA) techniques provided optimized conditions for glucose oxidation and detection. A preconcentration step that involved 10 minutes accumulation at open circuit potential before SWV running led to the lowest limit of detection and the highest sensitivity for glucose detection (5419.77 &micro, A&middot, mM&minus, 1&middot, cm&minus, 2 at + 1.1 V vs. Ag/AgCl) vs. Cu-based electrodes reported to date in literature.

Fe(acac)3/silica/PVA hybrid xerogel nanocomposite was obtained by one pot acid catalysed sol-gel synthesis using the homogeneous mixture of iron(III) acetylacetonate (Fe(acac)3), tetraethylorthosilicate (TEOS), and polyvinyl alcohol (PVA). Nominal composition ratio of iron oxide/silica was 15/85 (weight percent). Nitric acid was used as catalyst. Another sample of Fe(acac)3/silica xerogel without PVA addition was prepared in the similar processing conditions. Based on thermal analysis studies, the thermal behaviour of both xerogel samples was unveiled and it allowed choosing the optimal calcination temperatures in order to obtain iron oxide silica magnetic nanocomposite samples. The two xerogel (with and without PVA) samples were thermally treated, in air, at 220, 260 and 300?C and characterized by different techniques. XRD investigations revealed phase composition evolution with calcination temperature, from cubic spinel phase (maghemite) to hexagonal stable hematite containing nanocomposite of 10-20 nm average crystallite size. These findings were confirmed by M?ssbauer spectroscopy. Up to 300?C, the surface area and total pores volume increased with temperature for all samples. By calcination at the same temperature, the hybrid xerogel containing PVA resulted in significantly higher magnetization and free volume values in comparison with the sample without PVA.

Three cadmium(II) complexes formulated as [Cd3L(CH3COO)4]·H2O (1), [Cd2L(NO3)2]·CHCl3 (2) and [Cd5L2(CH3COO)6] (3) have been obtained by reacting appropriate CdII salts with N,N’-bis[(2-hydroxybenzilideneamino)-propyl]-piperazine (H2L). X-ray single-crystal analysis shows that compounds 1-3 crystallize in the triclinic space group P 1 ¯ and consist of CdII ions with distorted octahedral geometry, connected to form trinuclear (1) and binuclear (2) units and a combination of both in 3. A piperazine moiety, in chair conformation, acts as a bridge between these polynuclear units to form 1D chains. Blue luminescence in the range of 460−490 nm was observed upon excitation at 345 nm in the solid state. The investigation of the degradation of the dye Congo Red (CR) under visible light, revealed very good photocatalytic activity of the obtained coordination polymers. The photocatalytic process follows first-order reaction kinetics.

The network of chemical reactions of 2,6-bis(5-bromo-2-hydroxybenzylidene)cyclohexanone (BHBC) when subjected to light and different pH values has been investigated. The pH dependent species involved in the chemical network have been identified and characterized by NMR and UV-VIS spectroscopy. Direct pH jumps were carried out by adding a strong acid to equilibrated solutions of trans-chalcone (Ct) forming the flavylium cation which was stable only under extremely acidic conditions (pH < 0.5). The single crystal X-ray study and NMR analysis has confirmed the structure of the new flavylium cation. In the case of a reverse pH jump, the Ct species interconverted instantaneously into deprotonated trans-chalcone (Ct2−) around pH 12. A new colorless compound 3,11-dibromo-7,8-dihydro-6H-chromeno[3,2-d]xanthene (B–B) isolated from the equilibrated solution of trans-chalcone species in methanol after long periods of time (100 h) under dark conditions has been isolated and fully characterized by NMR and X-ray diffraction. The rate of the reaction increased when the solution of trans-chalcone was exposed to light and the total conversion of Ct into the spiropyran-like compound (B–B) was achieved in about 30 minutes. The B–B form was stable under neutral and basic conditions, while at low pH values it converts into a cationic AH+ form.

The kinetics and thermodynamics of the 2,6-bis(2-hydroxybenzilidene)cyclohexanone chemical reactions network was studied at different pH values using NMR, UV-vis, continuous irradiation, and flash photolysis. The chemical behavior of the system partially resembles anthocyanins and their analogue compounds. 2,6-Bis(2-hydroxybenzilidene)cyclohexanone exhibits a slow color change from yellow to red styrylflavylium under extreme acidic conditions. The rate constant for this process (5 × 10(-5) s(-1)) is pH independent and controlled by the cis-trans isomerization barrier. However, the interesting feature is the appearance of the colorless compound, 7,8-dihydro-6H-chromeno[3,2-d]xanthene, isolated from solutions of acid to neutral range, characterized by (1)H NMR and single crystal X-ray diffraction. Light absorption by 2,6-bis(2-hydroxybenzilidene)cyclohexanone solutions immediately after preparation exclusively results in cis-isomer as photoproduct, which via hemiketal formation yields (i) red styrylflavylium by dehydration under extremely acidic solutions (pH1) and (ii) colorless 7,8-dihydro-6H-chromeno[3,2-d]xanthene by cyclization in solutions of acid to neutral range.

Here, we report the full characterization of liquid crystal behavior of 2,4-bis(4-dodecyloxybenzylidene)cyclohexanone (DBCH) by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and X-ray diffraction. Two different crystalline states and a smectic- C phase ( a = 36.9–38.1 Ǻ depending on temperature) are found. The compound was also investigated using NMR, FT-IR and fluorescence spectroscopy and the results are also reported.

The pH-dependent photochromic behaviour of a curcumin analogue, 2,6-bis(2-hydroxybenzilidene)cyclohexanone (HBC) has been investigated. The identification of stable and unstable species from network reaction was done by combination of NMR, UV–vis and fluorescence spectroscopy. The structure of stable species was established by 13C NMR, 1H NMR and 2D NMR spectra: DQF-COSY, HSQC and HMBC. The results indicate that HBC could be used as pH sensor on a 1–5 scale. Experimental results were correlated by theoretical calculations using ZINDO/S/CI semi-empirical methods. HBC exhibits fluorescent properties both in acidic and neutral media and in basic environment the fluorescence is quenched.

The heterometallic complexes [Cu(VO)2(CSN2H4)3Cl(OH)4]·H2O, [Cu2(VO)2(CSN2H4)2(C2H3O2)2·(OH)4], and [Cu2(VO)3(CSN2H4)4(C2H3O2)4(OH)4] were prepared and characterized in terms of their molecular electrical conductivity, electronic and IR spectra, and thermal behavior. A polymeric structure is proposed in which a thiourea ligand is bonded via a sulfur atom to the tetracoordinated copper(I) and via amino groups to the oxovanadium(IV) ion. The polymeric nature of the complexes is due to bridging via the OH, thiourea, and/or acetate moieties between oxovanadium(IV) coordination centers.

New mixed-ligand complexes, [M2(BAMP)(bipy)2][MCl4]2, M=Co+2(1), Cu+2(2), [M2(TAMEN)(bipy)2][MCl4]2, M=Fe+2(3), Co2+(4), and [Fe2(TAMEN)(bipy)2][FeCl6]2 (5), where BAMP and TAMEN stand for the Mannich bases N,N′-bis(antipyryl-4-methylene)-piperazine and N,N′-tetra(antipyryl-4-methylene)-1,2-ethane-diamine, respectively, have been obtained and characterized by elemental analyses, conductometric and magnetic susceptibility measurements at room temperature, mass spectrometry, UV-Vis, infrared, and mass spectroscopy, and 1H NMR spectra for the ligands.

The mononuclear complex, [Co(TAMEN)](ClO(4))(2) (DMSO), containing the Mannich base N,N'-tetra-(4-antipyrylmethyl)-1,2-diaminoethane (TAMEN) as ligand, was synthesized and characterised by conductometric, electronic and infrared spectroscopic properties. The single-crystal X-ray structure show the presence of two well defined units, [Co(TAMEN)](2+) and (ClO(4))(-). The complex cation contains cobalt(II) in the pseudo octahedral environment created by the N(2)O(4) donor set of TAMEN. The cobalt(II) complex have been screened for its cytotoxic activity against three cultured human cell lines established from hepatoma (Hep G2), breast (MCF-7) and lung (A549) cancers as well as on non-tumor bovine kidney (MDBK) cells. The cytotoxic activity of the ligand TAMEN was assessed on one tumor (Hep G2) and one non-tumor (MDBK) cell lines. The cobalt(II) compound was found to decrease in a time- and concentration- dependent manner the viability of tumor (A549, MCF-7, Hep G2) cell lines, while the ligand TAMEN expressed proliferative activity on hepatoma (HepG2) and bovine kidney (MDBK) cells, especially after prolonged incubation.

The thermal decomposition in air and in nitrogen atmosphere of binuclear complex compounds of Cu(II) and Co(II) containing the Mannich base N,N'-tetra(4-antipyrylmethyl)-1,2 diaminoethane (TAMEN) as a ligand, Cu 2 (TAMEN)Cl 4 and Co 2 (TAMEN)Cl 4 , were investigated. X-ray powder diffractometry, infrared spectroscopy and simultaneous thermogravimetry-differential thermal analysis (TG-DTA), have been used to characterize and to study the thermal behavior of these compounds. The results provided information concerning the stoichiometry, crystallinity, thermal stability and decomposition mechanism of the compounds.

The synthesis of Schiff bases N,N′‐bis(4‐dodecyloxy‐benzylidene‐N‐propyl)‐piperazine (2) and N,N′‐bis‐[4‐(4′‐octyloxy‐benzoic)‐ester‐benzylidene‐N‐propyl]‐piperazine (6) in a multistep process is reported. The intermediates as well as the products were characterized by elemental analysis, melting point and IR, 1H and 13C‐NMR spectroscopy. The complex formation of these Schiff bases with copper(II) perchlorate resulted in disruption of the imino bond and yielded N,N′‐bis(3‐aminopropyl)piperazineperchloratocopper(II) perchlorate, Cu(L)(ClO4)2, where L stands for N,N′‐bis(3‐aminopropyl‐)piperazine. The nature of the complex is established by elemental analyses, IR and Raman spectroscopy and its structure by X‐ray diffraction measurements. The mesomorphic ordering of the ligands have been checked.

The heterometallic complex [Cu(VO)2(C10H8N2)2(C2O4)3·2H2O] has been prepared and characterised by electronic and IR spectra, molecular electrical conductivity and thermal behaviour. A polymeric structure is proposed with oxalate and 4,4′-dipyridine acting as bridging ligands and VO(IV) of C4v symmetry and Cu(II) in octahedral surrounding the oxalate anion V4h.

The new Schiff base N,N′-bis(4-decyloxysalicyliden-N-n-propyl)-piperazine (ZOPP) was designed and synthesized. Structures were confirmed by elemental analysis and IR, 1H-NMR spectroscopy. ZOPP can act as ligand through the two set of donor atoms (one set: two nitrogen atoms and one oxygen) situated on each side of the piperazine bridge. The nature of the complexes depends strongly on the metal to ligand molar ratio. Thus, starting from metal to ligand of 1 to 1 ratio, where M=Cu(II), Ni(II), binuclear complexes with a polymeric structure have been obtained, whereas at metal to ligand molar ratio of 2 to 1, discrete binuclear complexes were formed.

Kinetics of thermal decomposition of three structurally similar complexes Co2Cu(C2O4)3 (R-diam)2, where R is ethyl, 1,2-propyl or 1,3-propyl, was studied under non-isothermal conditions and nitrogen dynamic atmosphere at heating rates of 5, 7, 10, 12 and 15 K min−1.

The new mononuclear complex [Ni(TAMEN)](ClO4)2·DMF (TAMEN = N,N′-tetra-(4-antipyrylmethyl)-1,2-diaminoethane) has been synthesized and its crystal structure was determined by single-crystal X-ray diffraction. It crystallizes with monoclinic symmetry, space group P21/c (no. 14) and unit cell parameters of a = 10.8736(3), b = 10.9560(4), c = 45.820(2) A, β = 90.23(1)°, Z = 4. The TAMEN molecule acts as a hexadentate ligand incorporating a 1,2-diaminoethane bridge in the staggered conformational gauche isomer. The nickel(II) ion is octahedrally coordinated with metal-ligand distances ranging from 2.023(2) to 2.145(3) A. Electronic and vibrational spectroscopy data agree well with the crystal structure.

The thermal behaviour of the mixed-ligand complexes of cobalt(II) and copper(I) ions with antipyrine derivatives of 1,2-ethanediamine or piperazine (BAMP and TAMEN), with water and with 2-mercapto-benzothiazole (Hmbt) was investigated. The complexes contain 2-mercaptobenzothiazole (Hmbt, in the case of cobalt(II) ion) or dimercaptobenzothiazine (mbt–mbt, in the case of copper(I) ion) molecules as ligands and perchlorate (ClO4–) or thiocyanate (SCN – ) ion as counterion. By heating, water and ligands release the solid phase at lower temperature. At higher temperatures process of different organic reactions of ligands (e.g. polymerization, polycondensation) could be suggested to interpret the relative high final mass values.

The synthesis of the Mannich base N,N′-tetra(antipyryl-4-methyl)-1,2-ethanediamine (TAMEN) (1), its crystal structure as well as the synthesis and the crystal structure of the copper complex [Cu(TAMEN)](ClO4)2·H2O·DMF (2) are reported. C50H56N10O4·2C2H5OH (TAMEN·2EtOH) crystallizes with triclinic symmetry, space group , lattice parameters: a = 877.3(1), b = 1078.1(1), c = 1433.3(2) pm, α = 71.93(1), β = 82.16(1), γ = 84.54(1)° and Z = 1. The copper complex [Cu(TAMEN)](ClO4)2·H2O·DMF also crystallizes with triclinic symmetry, space group , lattice parameters: a = 1279.2(2), b = 1485.6(2), c = 1513.6(2) pm, α = 98.04(1), β = 101.24(1), γ = 94.66(1)° and Z = 2. The copper(II) atom is six-coordinate with an elongated pseudo-octahedral geometry due to a strong Jahn-Teller effect.

The syntheses and the crystal structures of the complexes Co2(BAMP)Cl4 (1) and [Cu(BAMP)(H2O)](ClO4)2(2) are reported. 1 crystallizes in the monoclinic space group C2/c with the unit cell dimensions a = 3129.7(4), b = 772.9(1), c = 1503.4(2) pm, β = 112.47(1)° and Z = 4. Cobalt(II) is surrounded in the fashion of a distorted tetrahedron built from the NO donor atoms of the BAMP ligand and two chloride anions. The copper compound 2 crystallizes in the monoclinic space group I2/a with unit cell dimensions of a = 2539.0(3), b = 1448.1(1), c = 1887.0(2) pm, β = 93.40(1)° and Z = 8. Copper(II) coordination can be described as a square-based pyramid with the N2O2 donor atoms of the BAMP molecule forming the basal plane completed by a water molecule in the apical position. Spectroscopic (IR and UV-Vis) and conductivity data of the new complex compounds are presented. Neue Kupfer(II)- und Cobalt(II)-Komplexe mit dem BAMP-Liganden (N,N′-Bis(antipyryl-4-methyl)-piperazin). Kristallstrukturen von Co2(BAMP)Cl4 und [Cu(BAMP)(H2O)](ClO4)2 Die Verbindungen Co2(BAMP)Cl4 (1) und [Cu(BAMP)(H2O)](ClO4)2 (2) wurden synthetisiert und durch Einkristallrontgenstrukturanalyse charakterisiert. Der Co-Komplex kristallisiert monoklin (C2/c, a = 3129.7(4), b = 772.9(1), c = 1503.4(2) pm, β = 112.47(1)° und Z = 4). Das Co2+-Ion ist verzerrt tetraedrisch von den NO-Atomen des BAMP-Liganden und den Chlorid-Ionen koordiniert. Die Cu-Verbindung 2 kristallisiert in der monoklinen Raumgruppe I2/a mit acht Formeleinheiten in der Elementarzelle (a = 2539.0(3), b = 1448.1(1), c = 1887.0(2) pm, β = 93.40(1)°). Die N2O2-Donor-Atome des BAMP-Liganden bilden gemeinsam mit einem H2O-Molekul einen quadratisch-pyramidablen Koordinationspolyeder um das Cu-Kation. An beiden Verbindungen wurden spektroskopische (IR und UV-Vis) und Leitfahigkeits-Messungen durchgefuhrt.

The complex Co(C14H13NO)2Cl2 with the protonated N-salicylidene-p-toluidine ligand was synthesized from an ethanolic solution of CoCl2·6H2O and N-salicylidene-p-toluidine. The crystal structure was determined from X-ray single crystal data (monoclinic, space group Cc, a = 1496.2(3) pm, b = 1257.4(4) pm, c = 1544.6(3) pm, β = 115.01(1)°, Z = 4). Co2+ adopts a distorted tetrahedral geometry. The UV-Vis and IR spectra of the complex are discussed.

Two new Schiff base ligands 1 and 2 (where 1 = 4-(2-hydroxybenzilidenamino)-phenyl-4-(decyloxy)-2-(pent-4-enyloxy)benzoate, 2 = 4-(4-(decyloxy)-2-hydroxybenziliden amino)-phenyl-4-(decyloxy)-2-(pent-4-enyloxy)benzoate) and their copper (Cu)(II) complexes have been synthesised and characterised. The derivatives were fully characterised structurally, and their mesomorphic behaviour was investigated by polarised optical microscopyand differential scanning calorimetry. The structure of Cu(II) complex having 1 as ligand (3) was determined by X-ray diffraction. The Schiff base ligands exhibit enantiotropic nematic phases, the Cu(II) complex 4 shows monotropic nematic phase behaviour, while compound 3 does not show mesomorphism.

The new sulfide bridged-polynuclear complexes Cu2(VO)4- (C2O4)4S2L4ċnH2O, where for L=1, 10-phenanthroline, n=5 and for L=2, l0-bipyridine, n=7, have been synthesized and characterized by elemental and thermal analyses, electronic and IR spectroscopy. These data as well as magnetic moments and EPR spectra strongly support a structure in which four [VO(L)(C2O4)(H2O)] units act as ligands toward the two copper(II) centers through the oxalate anion. Each of the oxalate anions act as a tridentate ligand and the core of the complexes involve a copper-sulfide-copper moiety.

The reaction between copper(II) acetate with 2,2′-bipyridine and K3[Cr(C2O4)3] leads to the novel salt [Cu(bipy)2(CH3COO)][Cu(bipy)2(Cr(C2O4)3)]·∼10.5H2O, 1 (bipy=2,2′-bipyridine). The crystal structure of 1 consists of mononuclear cationic species [Cu(bipy)2(CH3COO)]+ and heterobinuclear anionic units, [Cu(bipy)2(Cr(C2O4)3)]−. The tris-oxalato-chromium entity behaves as a monodentate ligand toward the copper(II) ion within the complex anion. The distance between Cr(III) and Cu(II) across the bridging oxalato group is 5.056(2) A. The copper(II) ions exhibit a distorted trigonal bipyramidal surrounding in both cationic and anionic species. The π–π stacking interaction between bipy ligands of the neighboring [Cu(bipy)2(CH3COO)]+ mononuclear entities leads to chains of copper atoms running along the b axis. Magnetic susceptibility measurements of 1 in the temperature range of 1.9–290 K reveal a quasi-Curie law behavior, the magnetic coupling between Cr(III) and Cu(II) through the bridging oxalato group with the bidentate/monodentate coordination mode being negligible.

Mixed-ligand complexes of the type M2L(TAB)nX4 [L = N,N′-bis(4-antipyryl-methyl)piperazine (BAMP), or N,N′-tetra(4-antipyrylmethyl)-l,2-diaminoethane (TAMEN) and 2-aminobenzothiazole (TAB), X - NCS or CIO4, M - Co, n - 2, or M - Cu, n = 4] were synthesized and investigated. The IR and Raman spectra revealed that the ligands L are coordinated through the carbonyl oxygen atom of the antipyrine and the nitrogen atom of the piperazine or 1,2-ethanediaminc bridge, except in Cu2(TAMEN)(TAB)4(ClO4)4, in which case TAMKN is coordinated to the metal only through the carbonyl oxygen. Steric considerations explain the bonding of TAB through the exocyclic or endocyclic nitrogen.

This paper describes a new case of the bis(antipyryl-methyl)-piperazine [BAMP] ligand being in the “boat”-conformation and acting as a tetradentate. But unlike in Co(BAMP)(NCS) 2 , which is the only complex with BAMP acting as tetradentate known so far, the coordinated copper(II) is connected via a iodo-bridge to a Cu I I 2 -moiety. The synthesis, elemental analysis, spectroscopic (far- and mid-FTIR, UV–Vis) and structural characterization (X-ray diffraction) as well as magnetochemical and conductivity data of this novel mixed valence binuclear complex Cu I Cu II (BAMP)I 3 are presented.

Polar Iminoboranes: Reactions of (tert-Butylimino)(pentafluorophenyl)borane The reactions of the iminoborane C6F5-B≡N-tBu (1) with nitriles and isonitriles are studied. Nitriles RCN give cycloadducts either of the triazadiboracyclohexane type (3a; R = iPr) or of the tetrazatriborabicyclo[4.2.0]octane type [4b-d; R = Ph, p-C6H4Me, p-C6H4(CF3)] or of the (iminomethyl)borazine type (5e, f; R = Me, Et). Isonitriles RNC yield mainly adducts of RNC to a cycloaddition product of the diazadiboracyclopentane type (6a, b; R = 2,6-C6H3Me2, tBu); the adduct of RNC to a diazadiboracyclobutane may be a side-product (7b; R = tBu). The iminoborane Me3Si(tBu)N-B=NtBu reacts with two molecules of (2,6-C6H3Me2)NC to give the corresponding azaboracyclobutane 8. The iminoborane tBu-B≡N-C6F5 (1′), formed by gas-phase elimination of ClSiMe3 from Cl(tBu)B = N(C6F5)SiMe3 (9), cyclodimerizes more readily than the isomeric borane 1. The cyclodimer 2′ gives 1:1-addition reactions with tBuNC, PMe3, and MeNC, respectively; the added components fluctuate in solutions of the products 7b'-d'. A similar fluctuation is observed with the 1:1 adduct 7c from PMe3 and the cyclodimer 2 of the iminoborane 1. The products 3a, 5e, 6a, 8 crystallize in the space groups P21/c, P21/n, Pbca, and P21/c, respectively.

The synthesis and properties of new cobalt, nickel and copper complexes of general formula M2(TAMEN)Cl4 [M = Co, Ni, Cu; TAMEN = N,N,′-tetra(4-antipyrylmethyl)-1,2-diaminoethane; antipyryl- = 2,3-dimethyl-1-phenyl-3-pyrazoline-5-one] and the 1H-NMR spectrum of the ligand TAMEN are reported. TAMEN bridges the two metal centres via two groups of donor atoms, each being formed of the carbonylic oxygens and a 1,2-diaminoethane nitrogen atom.