Cyclic carbonate synthesis from CO2and epoxides using zinc(II) complexes of arylhydrazones of β-diketones

Zinc(II) complexes of arylhydrazones of β-diketones (AHBD) were used for the first time as catalysts combined with tetrabutylammonium bromide (TBABr), in the coupling reaction between CO2 and epoxides. The influence of pressure and temperature on cyclic carbonate formation was investigated, as well as the catalytic activity toward different substrates (e.g. styrene oxide, propylene oxide and cyclohexene oxide). The molar ratio between metal complex and TBABr was determined for maximum catalytic activity

Water-soluble Al(iii), Fe(iii) and Cu(ii) formazanates: synthesis, structure, and applications in alkane and alcohol oxidations

A series of water-soluble metal formazanates, [Al2(OH)2(H2O)8](HL)2 (1), [{Fe(H2O)4}(HL)(H2L)]·2H2O (2) and [Cu(en)2(H2O)2][CuL(H2O)2]2 (3), were synthesized by the reaction of sodium 2-(2-((E)-cyano((E)-(2-sulfonatophenyl)diazenyl)methylene)hydrazineyl) benzenesulfonate (Na2HL) with Al(NO3)3·9H2O, FeCl3·6H2O and Cu(NO3)2·3H2O (in the presence of ethylenediamine) in methanol, respectively. The formazan pro-ligand Na2HL and its complexes 1-3 were characterized by ESI-MS, 1H/13C NMR (for Na2HL), IR spectroscopy, elemental and X-ray diffraction analyses (for 1-3). According to the X-ray analysis, the formazanate behaves as an anion or displays a mono- or bidentate coordination mode, for the Al, Fe or Cu centre, respectively. All complexes were tested as catalysts for the peroxidative (with H2O2) oxidation of cyclohexane and cyclohexanol to the coresponding organic products at room temperature. The complexes 2 and 3 are active homogeneous catalysts for the microwave-assisted peroxidative oxidation with aqueous H2O2 of cyclohexane (to cyclohexanol and cyclohexanone) and cyclohexanol to cyclohexanone. © 2022 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique

C‐Heterogenized Re Nanoparticles as Effective Catalysts for the Reduction of 4‐Nitrophenol and Oxidation of 1‐Phenylethanol

Rhenium nanoparticles (Re NPs) supported on Norit (activated carbon—C) and graphene (G) were prepared by a solvothermal method under microwave irradiation (MW). The synthesised heterogeneous catalysts were characterised and tested as reduction and oxidation catalysts, highlighting their dual catalytic behaviour. In the first case, they were used, for the first time, to reduce 4‐nitrophenol, in aqueous medium, under MW irradiation. Re catalysts were easily recovered by centrifugation and recycled up to six times without significant activity loss. However, the same Re catalysts in MW‐assisted oxidation of 1‐phenylethanol with no added solvent experienced a significant loss of activity when recycled. The higher activity of the rhenium nanoparticles supported on graphene (Re/G) catalyst in both reactions was assigned to the higher dispersion and smaller particle size of Re NPs when graphene is the support. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

DNA and BSA binding and cytotoxic properties of copper(II) and iron(III) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands

Several known water soluble [Cu(1κN,O2:2κO-HL1)(S)]2 [S = CH3OH (1), (CH3)2NCHO (2)] and [Cu(κN-HL1)(en)2]·CH3OH·H2O (3) CuII complexes were prepared by reaction of CuII nitrate hydrate with the new (E/Z)-4-(2-(1-cyano-2-ethoxy-2-oxoethylidene)hydrazinyl)-3-hydroxybenzoic acid (H3L1), in the presence (for 3) or absence (for 1 and 2) of ethylenediamine (en), while the FeIII complex [Fe(κN3-HL2)2] (4) was synthesized by treatment of iron(iii) chloride hexahydrate with the new (1E,1E)-N′,2-di(1H-1,2,4-triazol-3-yl)diazenecarbohydrazonoyl cyanide (H3L2). The interaction of calf thymus DNA (CT DNA) and bovine serum albumin (BSA protein) with complexes 1-4 has been investigated by absorption and fluorescence titration methods. The observed DNA binding constants, number of DNA binding sites (s ≤ 1) for the complexes and viscosity data suggest the intercalative mode of binding to CT DNA. All the complexes show good binding propensity to the BSA protein, giving KBSA values of 0.97(±0.10) × 106 (1), 1.19(±0.09) × 106 (2), 0.50(±0.01) × 106 (3) and 1.06(±0.08) × 106 M-1 (4). An in vitro anti-proliferative study establishes the anticancer potency of complexes 1-4 and cisplatin against the human cervical (HeLa) and breast (MCF7) cancer cell lines; noncancer breast epithelial (MCF10) cells were also investigated. The observed IC50 values of complexes 1 (8.3, 11.9 and 44.8 μM), 2 (7.0, 7.1 and 35.6 μM), 3 (18.1, 20.4 and 58.8 μM), 4 (13.2, 15.1 and 79.4 μM) and cisplatin (4.02, 3.42 and 89.5 μM) against the HeLa, MCF7 and MCF-10a cells, respectively, suggest that 2 can be explored further as a potential anticancer drug. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2017

Oxido-and dioxido-vanadium(V) complexes supported on carbon materials: Reusable catalysts for the oxidation of cyclohexane

Oxidovanadium(V) and dioxidovanadium(V) compounds, [VO(OEt)L] (1) and [Et3NH][VO2L] (2), were synthesized using an aroylhydrazone Schiff base (5-bromo-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H2L). They were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), (1H and51V) nuclear magnetic resonance (NMR), electrospray ioniza-tion mass spectrometry (ESI-MS) and single crystal X-ray diffraction analyses. Both complexes were immobilized on functionalized carbon nanotubes and activated carbon. The catalytic performances of 1 and 2, homogenous and anchored on the supports, were evaluated for the first time towards the MW-assisted peroxidative oxidation (with tert-butylhydroperoxide, TBHP) of cyclohexane under heterogeneous conditions. The immobilization of 1 and 2 on functionalized carbon materials improved the efficiency of catalytic oxidation and allowed the catalyst recyclability with a well-preserved catalytic activity. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Mechanochemical and Conventional Synthesis of Copper(II) Coordination Polymers Bearing Arylhydrazone of Acetoacetanilide and Their Catalytic Activity in Conversion of Acetone to Acetic Acid

Copper(II) coordination polymers, [Cu(μ2-HL)]n⋅n(CH3)2C=O (1), [Cu(μ1-HL)(CH3OH)]n (2) and [Cu(μ1-HL)(H2O)]n (3) were isolated by recrystallization (in acetone, methanol and dimethylformamide, respectively) of an intermediate produced by a solid state ball milling reaction of CuCl2⋅2H2O with 2-(2-(1,3-dioxo-1-(phenylamino)butan-2-ylidene)hydrazinyl)benzoic acid (H3L). Reaction under conventional fully solution-based conditions of CuCl2⋅2H2O with H3L in acetone and dimethylformamide leads to 3, and in methanol to the known monomeric compound [Cu(HL1)(H2O)(CH3OH)] (4). All the coordination polymers 1−3 act as homogenous catalysts for the peroxidative (H2O2) oxidation of acetone to acetic acid with yields up to 50% and at room temperature. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei

DNA and BSA binding and cytotoxic properties of copper(II) and iron(III) complexes with arylhydrazone of ethyl 2-cyanoacetate or formazan ligands

Several known water soluble [Cu(1κN,O2:2κO-HL1)(S)]2 [S = CH3OH (1), (CH3)2NCHO (2)] and [Cu(κN-HL1)(en)2]·CH3OH·H2O (3) CuII complexes were prepared by reaction of CuII nitrate hydrate with the new (E/Z)-4-(2-(1-cyano-2-ethoxy-2-oxoethylidene)hydrazinyl)-3-hydroxybenzoic acid (H3L1), in the presence (for 3) or absence (for 1 and 2) of ethylenediamine (en), while the FeIII complex [Fe(κN3-HL2)2] (4) was synthesized by treatment of iron(iii) chloride hexahydrate with the new (1E,1E)-N′,2-di(1H-1,2,4-triazol-3-yl)diazenecarbohydrazonoyl cyanide (H3L2). The interaction of calf thymus DNA (CT DNA) and bovine serum albumin (BSA protein) with complexes 1-4 has been investigated by absorption and fluorescence titration methods. The observed DNA binding constants, number of DNA binding sites (s ≤ 1) for the complexes and viscosity data suggest the intercalative mode of binding to CT DNA. All the complexes show good binding propensity to the BSA protein, giving KBSA values of 0.97(±0.10) × 106 (1), 1.19(±0.09) × 106 (2), 0.50(±0.01) × 106 (3) and 1.06(±0.08) × 106 M-1 (4). An in vitro anti-proliferative study establishes the anticancer potency of complexes 1-4 and cisplatin against the human cervical (HeLa) and breast (MCF7) cancer cell lines; noncancer breast epithelial (MCF10) cells were also investigated. The observed IC50 values of complexes 1 (8.3, 11.9 and 44.8 μM), 2 (7.0, 7.1 and 35.6 μM), 3 (18.1, 20.4 and 58.8 μM), 4 (13.2, 15.1 and 79.4 μM) and cisplatin (4.02, 3.42 and 89.5 μM) against the HeLa, MCF7 and MCF-10a cells, respectively, suggest that 2 can be explored further as a potential anticancer drug. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2017

Diastereomeric dinickel(ii) complexes with non-innocent bis(octaazamacrocyclic) ligands: isomerization, spectroelectrochemistry, DFT calculations and use in catalytic oxidation of cyclohexane

Diastereomeric dinickel(ii) complexes with bis-octaazamacrocyclic 15-membered ligands [Ni(L1-3-L1-3)Ni] (4-6) have been prepared by oxidative dehydrogenation of nickel(ii) complexes NiL1-3 (1-3) derived from 1,2- and 1,3-diketones and S-methylisothiocarbohydrazide. The compounds were characterized by elemental analysis, ESI mass spectrometry, and IR, UV-vis, 1H NMR, and 13C NMR spectroscopy. Single crystal X-ray diffraction (SC-XRD) confirmed the isolation of the anti and syn isomers of bis-octaazamacrocyclic dinickel(ii) complexes 4a and 4s, the syn-configuration of 5s and the anti-configuration of the dinickel(ii) complex 6a. Dimerization of prochiral nickel(ii) complexes 1-3 generates two chiral centers at the bridging carbon atoms. The anti-complexes were isolated as meso-isomers (4a and 6a) and the syn-compounds as racemic mixtures of R,R/S,S-enantiomers (4s and 5s). The syn-anti isomerization (epimerization) of the isolated complexes in chloroform was disclosed. The isomerization kinetics of 5a was monitored at five different temperatures ranging from 20 °C to 50 °C by 1H NMR spectroscopy indicating the clean conversion of 5a into 5s. The activation barrier determined from the temperature dependence of the rate constants via the Eyring equation was found to be ΔH‡ = 114 ± 1 kJ mol−1 with activation entropy ΔS‡ = 13 ± 3 J K−1 mol−1. The complexes contain two low-spin nickel(ii) ions in a square-planar coordination environment. The electrochemical behavior of 4a, 4s, 5s and 6a and the electronic structure of the oxidized species were studied by UV-vis-NIR-spectroelectrochemistry (SEC) and DFT calculations indicating the redox non-innocent behavior of the complexes. The dinickel(ii) complexes 4a, 4s, 5s and 6a/6s were investigated as catalysts for microwave-assisted solvent-free oxidation of cyclohexane by tert-butyl hydroperoxide to produce a mixture of cyclohexanone and cyclohexanol (KA oil). The best value for KA oil yield (16%) was obtained with a mixture of 6a/6s after 2 h of microwave irradiation at 100 °C. © 2022 The Royal Society of Chemistry