Molybdenum Complexes Derived from 2-Hydroxy-5-nitrobenzaldehyde and Benzhydrazide as Potential Oxidation Catalysts and Semiconductors.

This study aimed to synthesize molybdenum complexes coordinated with an aroyl hydrazone-type ligand (H2L), which was generated through the condensation of 2-hydroxy-5-nitrobenzaldehyde with benzhydrazide. The synthesis yielded two types of mononuclear complexes, specifically [MoO2(L)(MeOH)] and [MoO2(L)(H2O)], as well as a bipyridine-bridged dinuclear complex, [(MoO2(L))2(4,4'-bpy)]. Those entities were thoroughly characterized using a suite of analytical techniques, including attenuated total reflectance infrared spectroscopy (IR-ATR), elemental analysis (EA), thermogravimetric analysis (TGA), and single-crystal X-ray diffraction (SCXRD). Additionally, solid-state impedance spectroscopy (SS-IS) was employed to investigate the electrical properties of these complexes. The mononuclear complexes were tested as catalysts in the epoxidation of cyclooctene and the oxidation of linalool. Among these, the water-coordinated mononuclear complex, [MoO2(L)(H2O)], demonstrated superior electrical and catalytic properties. A novel contribution of this research lies in establishing a correlation between the electrical properties, structural features, and the catalytic efficiency of the complexes, marking this work as one of the pioneering studies in this area for molybdenum coordination complexes, to the best of our knowledge.

Combined experimental and computational study of cis-trans isomerism in bis(L-valinato)copper(II).

Heating of polycrystalline cis aquabis(L-valinato)copper(II) at 90 °C resulted in a dehydrated powder. Recrystallization from aqueous solution of the obtained product yielded anhydrous trans bis(L-valinato)copper(II). The X-ray crystal and molecular structures of trans bis(L-valinato)copper(II) and cis aquabis(L-valinato)copper(II) are presented. Molecular modeling calculations were attempted to resolve factors that influenced the isomerization and crystallization of either the aqua cis- or the anhydrous trans-isomer. Conformational analyses of trans- and cis-isomers were completed in vacuo and in crystal by molecular mechanics, and in aqueous solution by molecular dynamics (MD) simulations using the same force field. Although the conformers with trans-configuration are the most stable in vacuo, those with cis-configuration form more favorable intermolecular interactions. Consequently, both cis- and trans-isomers are predicted to be present in aqueous solution. According to the crystal structure simulations and predictions, cis-isomer requires water molecules to form energetically more stable crystal packings than trans-isomer. The MD modeling of the self-assembly of 16 bis(L-valinato)copper(II) complexes in aqueous solution for the first time predicted the crystallization nucleus formation to proceed from monomers to oligomers by Cu-to-O(carboxylato) and/or N-H···O(carboxylato) weak bonds; these oligomers then bind together via water molecules until they acquire the right positions for noncovalent bonding like in the experimental crystal structures. Fifty-nanosecond MD simulations accomplished for a system consisting of equal numbers of complexes and water molecules at 298 and 370 K suggested complete cis-to-trans transformation at the higher temperature. Prevalence of either cis- or trans-conformers in water upon dissolvation may explain the crystallization results.

Dicyclo-hexyl-ammonium 2-methoxy-benzoate.

The asymmetric unit of the title compound, C(12)H(24)N(+)·C(8)H(7)O(3) (-), contains one dicyclo-hexyl-ammonium cation and one 2-methoxy-benzoate anion. Two cations and two anions are linked together to form a four-ion cluster through a set of N-H⋯O hydrogen bonds. Weak C-H⋯O hydrogen bonds connect the clusters into chains that are stacked along the crystallographic c axis.

Propane-2,2-diyl di-p-phenyl-ene dibenzoate.

The V-shaped propeller-like mol-ecule of the title compound, C(29)H(24)O(4), does not exhibit crystallographic twofold symmetry as the two benzene rings are twisted asymmetrically with respect to both the central propyl plane and the benzo-yloxy groups [4.6 (2), 43.6 (2)° and 45.07 (8), 69.50 (8)°]. In the crystal structure, centrosymmetrically related mol-ecules form a dimer through C-H⋯π inter-molecular inter-actions.

Self-assembly of cis and trans forms of the copper(II) complex with 1-aminocyclopropane-1-carboxylate into discrete trimers in the solid state.

A copper(II) complex with 1-aminocyclopropane-1-carboxylic acid assembles by apical Cu...O bonds and hydrogen-bonding interactions into discrete trimeric units that exhibit both cis and trans binding modes.