A benzoate bridged dinuclear mixed valence cobalt(III/II) complex with CoIIIO4CoII core: Synthesis, structure and investigation of its phenoxazinone synthase mimicking activity

Phenoxo-bridged dinuclear mixed valence cobalt(III/II) complexes with reduced Schiff base ligands: synthesis, characterization, band gap measurements and fabrication of Schottky barrier diodes

Two homometallic class-I dinuclear mixed valence cobalt complexes, [(N3)CoIIIL1(μ-C6H4(NO2)CO2)CoII(N3)] (1) and [(N3)CoIIIL2(μ-C6H4(NO2)CO2)CoII(N3)] (2), have been synthesized using multisite N2O4 coordination ligands, H2L1 {where H2L1 = (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-methoxyphenol) and H2L2 = (2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-ethoxyphenol)}. Each complex has been structurally characterized by single crystal X-ray diffraction and spectral analysis. Both the cobalt centers in these dinuclear complexes adopt a distorted-octahedral geometry, where the cobalt(iii) center resides at the inner N2O2 cavity and the cobalt(ii) center resides at the outer O4 cavity of the reduced Schiff base. Both of them show good electrical conductivity, which has been rationalized by band gap measurements. The band gap in the solid state has been determined by experimental and DFT calculations and it confirms that each of the two complexes behaves as a semiconductor. The space-charge-limited current (SCLC) theory is employed to evaluate the charge transport parameters such as effective carrier mobility and transit time for both complexes. The difference in the conductivity values of the complexes may be correlated with the strengths of extended supramolecular interactions in the complexes. Bader's quantum theory of atoms-in-molecules (QTAIM) is applied extensively to get quantitative and qualitative insights into the physical nature of weak non-covalent interactions. In addition, the non-covalent interaction reduced density gradient (NCI-RDG) methods well support the presence of such non-covalent intermolecular interactions.

Insight into the formation of H-bonds propagating the monomeric zinc complexes of a tridentate reduced Schiff base to form an infinite chain

The formation of an infinite 1D assembly is governed by the H-bonding interactions in the solid state structure of the two zinc complexes. It has been analyzed energetically using DFT calculations and several computational tools.

A theoretical insight into the formation of chalcogen bonding (ChB) interactions involving coordinated DMSO molecules as σ-hole donors and benzoate groups as σ-hole acceptors in a dinuclear copper(ii) complex

The formation of two chalcogen bonding (ChB) interactions involving coordinated DMSO molecules as σ-hole donors and the O atoms of carboxylate groups as acceptors in a dimeric copper(ii) complex has been described.

Field-induced slow magnetic relaxation from linear trinuclear CoIII-CoII-CoIII to grid [2 × 2] tetranuclear mixed-valence cobalt complexes

By employing the ligand azotetrazolyl-2,7-dihydroxynaphthalene (H3ATD), two linear trinuclear mixed-valence cobalt complexes [CoIICoIII2(HATD)4(H2O)4]·4DMA·3H2O (1, DMA = N,N-dimethylacetamide) and [CoIICoIII2(HATD)4(DMF)2(H2O)2]·2DMF·2H2O (2, DMF = N,N-dimethylformamide) were synthesized. Two [2 × 2] grid-like tetranuclear ion-pair complexes [CoII2CoIII2(HATD)4(bpp)2(H2O)2][CoIII(HATD)2]2·8DMF·6H2O (3, bpp = 2,6-di(pyrazol-1-yl)pyridine) and [CoII2CoIII2(HATD)4(bpp)2(H2O)2][CoIII(HATD)2]2·8DMSO·4MeOH (4, DMSO = dimethyl sulphoxide) were obtained by the reaction of complex 1/2 with tridentate-chelating bpp in DMF and DMSO, respectively. The single-crystal X-ray diffraction analysis indicated that complexes 1 and 2 have a similar core, in which the DMA in 1 acts as a guest molecule, and the DMF in 2 acts as a coordinated molecule and guest molecule. Complexes 3 and 4 are isostructural. All the Co(ii) ions in 1-4 are present in a distorted octahedral geometry. The ac susceptibility measurements show that all complexes display frequency-dependent peaks in the out-of-phase (χm'') component of the alternating-current (ac) magnetic susceptibility data, which is the characteristic behavior of single molecule magnets (SMMs).

A theoretical insight on the rigid hydrogen-bonded network in the solid state structure of two zinc(ii) complexes and their strong fluorescence behaviors

A reduced Schiff base used as a fluorescence chemo-sensor for selective detection of zinc(ii). Strong fluorescence behaviors of two zinc(ii) complexes are correlated with the presence of a rigid hydrogen-bonded network in their solid state structure.