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Zinc oxide (ZnO) nanoparticles were obtained by thermal decomposition of one-dimensional zinc–benzenepolycarboxylato complexes as single- -source precursors at 450 °C in an air atmosphere. The mechanism and kinetics of thermal degradation of zinc–benzenepolycarboxylato complexes were analyzed under non-isothermal conditions in an air atmosphere. The results of X-ray powder diffraction and field emission scanning electron microscopy revealed hexagonal wurtzite structure of ZnO with an average crystallite size in the range of 39–47 nm and similar morphology. The band gap and the specific surface area of ZnO nanoparticles were determined using UV–Vis diffuse reflectance spectroscopy and the Brunauer, Emmett and Teller method, respectively. The photoluminescent, photocatalytic and antimicrobial properties of the ZnO nanoparticles were also examined. The best photocatalytic activity in the degradation of C. I. Reactive Orange 16 dye was observed for the ZnO powder where the crystallites form the smallest agglomerates. All ZnO nanoparticles showed excellent inhibitory effect against Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Escherichia coli.

A terephthalate-bridged heteronuclear Cu(II)–Mn(II) complex [Cu2Mn(dipya)2(tpht)3]n, I, where dipya is 2,2′-dipyridylamine and tpht is the anion of 1,4-benzenedicarboxylic (terephthalic, H2tpht) acid was synthesized under hydrothermal conditions. The obtained complex I was characterized by a single-crystal X-ray diffraction, FTIR spectroscopy, TG/DSC analysis and magnetic measurements. The Cu(II) and Mn(II) metal centers adopt distorted octahedral geometry and they are linked by bridging tpht ligands. Two crystallographically different tpht anions are coordinated as tridentate and hexadentate ligands forming two-dimensional layers. The layers are interconnected by hydrogen bonds and additionally stabilized by non-covalent C–H···π interactions. The measurements of magnetic susceptibility proved that I is an almost perfect paramagnet. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III45007]

Two series of poly(e-caprolactone) nanocomposites with different organo-modified clays (1 to 8 wt%) were prepared by the solution casting method. Organoclays with polar (Cloisite®C30B) and nonpolar (Cloisite®C15A) organic modifier and with different miscibility with poly(e-caprolactone) matrix, were chosen. Exfoliated and/or intercalated nanocomposite’s structures were obtained by using high dilution and an ultrasonic treatment for the composite preparation. The effect of the surface modification and clay content on the morphology, mechanical and thermal properties of the nanocomposites was studied. Scanning electron microscopy excluded the formation of microcomposite. The wide-angle X-ray diffraction analysis revealed that the tendency toward exfoliated structure is higher for the Cloisite®C30B, which had better miscibility with poly(e-caprolactone) matrix. Differences in spherulites’ sizes and morphology between two series of the nanocomposites were observed by the optical microscopy performed on as-casted films. Enthalpies of fusion and degrees of crystallinity were higher for nanocomposites than for neat poly(e-caprolactone) and increase with the clay loading in both series, as a consequence of the clay nucleating effect. Decreased thermal stability of nanocomposites was ascribed to thermal instability of organic modifiers of the clays. The Halpin-Tsai model was used to compare the theoretically predicted values of the Young’s modulus with experimentally obtained ones in tensile tests.[Projekat Ministarstva nauke Republike Srbije, br. 172062]

The title compound, (Hdipya)(H3pyr), where Hdipya is protonated 2,2’-dipyridilamine and H3pyr is monoanion of pyromellytic acid (H4pyr), was obtained from the reaction mixture containing Zn(II) ions, dipya, Na4pyr (the molar ratio 2 : 2 : 1) and HNO3. The products (micro- and single-crystalline) were characterized by X-ray structure determination, FT-IR spectroscopy and TG/DSC analysis. The most striking structural feature of (Hdipya)(H3pyr) are short inter- and extremely short intramolecular hydrogen bonds. These bonds mutually connect cations and anions making thin layers parallel to the crystallographic (223) plane. Also, quite unusual, linear proton-bound polymeric {H(H2pyr)-}n anions were identified in the structure. The results of crystal structure determination are compared with FT-IR and TG/DSC data. The low position of nas(COO) vibration at 1660 cm-1 is in accordance with strong hydrogen bonding. This value can be used as a measure of C=O bond order, which is calculated to be 1.81. [Projekat Ministarstva nauke Republike Srbije, br. 45007]

Four novel polymeric iron(III) complexes with 2,2’-bipyridine (bipy) and different aromatic polycarboxylato ligands as anions of phthalic (pht), isophthalic (ipht), terephthalic (tpht) and pyromellitic (pyr) acid were synthesized by ligand exchange reaction. The complexes were characterized by elemental and TG/DSC analysis, FTIR and diffuse reflectance UV-VIS-NIR spectroscopy and magnetic susceptibility measurements. Based on analytical and spectral data the formulae of the complexes are {[Fe4(bipy)2 (H2O)2(OH)6(pht)3]•2H2O}n (1), {[Fe4(bipy)2(Hipht)2(ipht)2(OH)6]•4H2O}n (2), {[Fe4(bipy)2(Htpht)2(OH)6(tpht)2]•4H2O}n (3) and {[Fe4(bipy)(H2O)8(OH)4 (pyr)2]•H2O}n (4). All complexes are red brown and low-spin with a distorted octahedral geometry and FeO6 or FeN2O4 chromophore. Polycarboxylato ligands have a bridging role in all cases, whereas monodentate COO groups are present in 2 and 3, bridging and chelate COO groups are established in 1 and 4. The thermal behaviour of 1-4 was investigated in detail and the molar dehydration enthalpies were calculated. According to the all those results, the structural formulae of the complexes 1-4 were proposed. [Projekat Ministarstva nauke Republike Srbije, br. III45007]

In this study, the synthesis, structure and physical properties of two series of thermoplastic polyurethanes based on hydroxypropyl terminated poly(dimethylsiloxane) (HP-PDMS) or hydroxyethoxy propyl terminated poly(dimethylsiloxane) (EO-PDMS) as a soft segment, and 4,4’-methylenediphenyl diisocyanate and 1,4-butanediol as a hard segment were investigated. Each series is composed of samples prepared with a different soft segment. The polyurethanes were synthesized by two-step polyaddition in solution. The effects of the type and content of PDMS segments on the structure, thermal and surface properties of copolymers were studied by 1H NMR, 13C NMR and two-dimensional NMR (HMBC and ROESY) spectroscopy, GPC, DSC, TGA, WAXS, SEM, water contact angle and water absorption measurements. Thermal properties investigated by DSC indicated that the presence of soft PDMS segments lowers the glass transition and melting temperatures of the hard phase as well as the degree of crystallinity. SEM analysis of copolymers with a lower soft segment content confirmed the presence of spherulite superstructures, which arise from the crystallization of the hard segments. When compared with polyurethanes prepared from HP-PDMS, copolymers synthesized from EO-PDMS with the same content of the soft segments have higher degree of crystallinity, better thermal stability and less hydrophobic surface. Our results show that the synthesized polyurethanes have good thermal and surface properties, which could be further modified by changing the type or content of the soft segments.

Carbon supported Pt and Pt-Rh-Sn catalysts were synthesized by microwave-polyol method in ethylene glycol solution and investigated for the ethanol electro-oxidation reaction. The catalysts were characterized in terms of structure, morphology and composition by employing XRD, STM and EDX techniques. STM analysis indicated rather uniform particles and particle size of below 2 nm for both catalysts. XRD analysis of the Pt/C catalyst revealed two phases, one with the main characteristic peaks of face centered cubic crystal structure (fcc) of platinum and another related to graphite like structure of carbon support Vulcan XC-72R. However, in XRD pattern of the Pt-Rh-Sn/C catalyst diffraction peaks for Pt, Rh or Sn cannot be resolved, indicating an extremely low crystallinity. The small particle sizes and homogeneous size distributions of both catalysts should be attributed to the advantages of microwave assisted modified polyol process in ethylene glycol solution. Pt-Rh- Sn/C catalyst is highly active for the ethanol oxidation with the onset potential shifted for more than 150 mV to negative values and with currents nearly 5 times higher in comparison to Pt/C catalyst. The stability tests of the catalysts, as studied by the chronoamperometric experiments, reveal that the Pt-Rh-Sn/C catalyst is evidently less poisoned then Pt/C catalyst. The increased activity of Pt-Rh-Sn/C in comparison to Pt/C catalyst is most probably promoted by bifunctional mechanism and the electronic effect of alloyed metals.

The crystal structure of the complex [Ni2(btc)(dipya)2(H2O)6]⋅6H2O·DMSO (btc = tetra-anion of 1,2,4,5-benzenetetracarboxylic acid, dipya = 2,2’-dipyridylamine) was refined in the triclinic system, space group P1, using low temperature (170 K) X-ray diffraction data. The compound consists of binuclear complex entities and lattice solvent molecules making pseudo-layers parallel to the 101 plane and channels parallel to the b-axis. The observed structural features were compared with the previously reported results and formula [Ni2(btc)(dipya)2(H2O)6]⋅4H2O based on room temperature X-ray diffraction data. A possible arrangement of the disordered lattice solvent molecules located in the structural channels is described and discussed. It is concluded that the layout of these molecules is non-centrosymmetric, although the remaining and main part of the structure is centrosymmetric. .

X-Ray crystal structure analysis of the complex [Cu(tpth)(phen)(H2O)]n, where tpht is the dianion of terephthalic acid and phen is 1,10-phenanthroline showed that two crystallographically different, but chemically identical tpht ions with monodentately coordinated COO groups exist; both tpht ions act as bridging ligands forming zigzag chains. The Cu(II) ions are in a deformed trigonal bipyramidal environment consisting of two N atoms from phen, two O atoms from different tpht ligands and one O atom from coordinated H2O molecule. The crystal data are as follows: C20H14CuN2O5, Mr = 425.87 triclinic system, space group P 1, a = 9.007(5), b = 10.557(5), c = 11.554(5) Å, α= 114.343(5), β = 92.942(5), γ = 114.516(5) º, V = 877.3(7) Å3, Z = 2 F(000) = 434, ρx = 1.612 g cm-3, μ = 1.281 mm-1, R1 = 0.0280 for 4363 reflections with I > 2σ(I), wR2 = 0.0785 for 5104 independent reflections and 254 refined parameters. Some of data were compared with isostructural Co(II) and Zn(II) complexes having the same ligands.