Syntheses of four new asymmetric Schiff bases and their Cu(II) complexes: Theoretical calculations to rationalize the packing of molecules in the crystals

New Bi-Nuclear Nickel(II) Complex-Based Salen Schiff Base: Synthesis, Crystal Structure, Spectroscopic, Thermal, and Electrical Investigations

In this study, a new bi-nuclear nickel complex [Ni2HL2(EtOH)2](Cl)(EtOH) of a Schiff base ligand, 2-[3-[2-hydroxybenzylideneamino]propyliminomethyl]phenol, was synthesized and characterized using UV/Vis, IR, HRMS, and TGA/DTA analysis. The molecular structure of the obtained complex was corroborated by the single crystal X-ray diffraction technique. It was found in the complex that two molecules of the ligand coordinate with two nickel atoms through azomethine-N and phenoxy-O, resulting in 6-coordinate distorted octahedral geometry, in which two ethanol molecules occupy the axial positions. The dielectric and electrical properties of the obtained samples were studied by impedance spectroscopy at different frequencies (from 1 Hz to 1 MHz) in the temperature range 298–343 K. It is found that the electrical conductivity of the Ni(II) complex is lower than that of the free ligand H2L, suggesting that the complexation traps the charge carriers contained in the ligand.

Templated synthesis of Ni(ii) complexes of unsymmetrical Schiff base ligands derived from 1,3-diamino-2-propanol: structural diversity and magnetic properties

A Ferromagnetically coupled tetranuclear, an antiferromagnetically coupled hexanuclear and a mononuclear Ni(II) complex of new unsymmetrical Schiff base ligands derived from 1,3-diamino-2-propanol have been obtained with a slight change in the carbonyl compounds.

The remarkable propensity for the formation of C–H⋯π(chelate ring) interactions in the crystals of the first-row transition metal dithiocarbamates and the supramolecular architectures they sustain

C–H⋯π(chelate ring) interactions play an important role in assembling first-row transition metal dithiocarbamates in their crystals.

Synthesis, Structure, and Biological Assays of Novel Trifluoromethyldiazepine–Metal Complexes

A new series of CuII, NiII, CoII, and MnIII complexes have been synthesised from the (6Z)-6-(7-trifluoromethyl-1,2,3,4-tetrahydro-5H-1,4-diazepin-5-ylidene)cyclohexa-2,4-dien-1-one (HDZP) ligand. These complexes were characterised by elemental, spectroscopic (IR and UV-vis), and thermal analysis. The crystal structure of Cu-DZP was solved by X-ray diffraction methods. The complex crystallises in the monoclinic P21/c space group, with two molecules per unit cell. The crystal lattice is stabilised by different intra and intermolecular interactions. Hirshfeld surface analysis was employed to obtain additional information about interactions that are responsible for the crystal packing. Quantitative examination of the fingerprint plots indicated the dominant contribution of H⋯H and H⋯X (X=O, F) interactions in the crystal packing. In addition, C–H⋯chelate ring (CR) and C–H⋯π interactions are described in detail and evaluated using DFT calculations. The antibacterial properties and the mechanism of inhibition of the main bacterial resistant mechanism, the biofilm, of the metal complexes and free ligand were investigated. [Mn(DZP)3]·2H2O was the most active complex against the Pseudomonas aeruginosa biofilm formation with an inhibition of 40%. However, none of the complexes inhibit more than 25% of the Gram negative bacteria microbial development. The most meaningful result was the bactericidal effect of [Co(DZP)2(H2O)2]·2H2O against the Gram positive bacteria, Staphylococcus aureus, which inhibits the bacterial development and significantly reduces the biofilm formation at low concentration.

Variation of nuclearity in NiII complexes of a Schiff base ligand: crystal structures and magnetic studies

Four Ni^II complexes have been synthesized by changing the reaction conditions and stoichiometry of the reactants. The magnetic coupling in the NiII4 complex is ferromagnetic whereas that in the NiII6 complex is antiferromagnetic.

The role of 3d–4f exchange interaction in SMM behaviour and magnetic refrigeration of carbonato bridged CuII2LnIII2 (Ln = Dy, Tb and Gd) complexes of an unsymmetrical N2O4 donor ligand

The role of exchange interaction between Cu(ii) and Ln(iii) ions in SMM behaviour and magnetocaloric effects has been extensively investigated by both experimental and theoretical CASSCF/RASSI-SO/SINGLE_ANISO methods.

A series of CuII–LnIII complexes of an N2O3 donor asymmetric ligand and a possible CuII–TbIII SMM candidate in no bias field

Among four isostructural heterometallic Cu^II–Ln^III complexes (Ln = Tb, Dy, Ho or Er) of an N₂O₃ donor asymmetric ligand, only the Cu^II–Tb^III complex shows SMM behavior at zero bias field but at applied bias field both the Cu^II–Tb^III and Cu^II–Dy^III complexes show SMM behavior.

Lone pair–π vs. σ-hole–π interactions in bromine head-containing oxacalix[2]arene[2]triazines

New bromine head-containing oxacalix[2]arene[2]triazines were synthesized. Owing to the bromine head and complementary V-shaped cavity, the solid state structure showed an intriguing and unique 1D-supramolecular chain-like self-assembly.

Mixed azido/phenoxido bridged trinuclear Cu(ii) complexes of Mannich bases: Synthesis, structures, magnetic properties and catalytic oxidase activities

Three mixed azido/phenoxido bridged trinuclear Cu(ii) complexes of tetradentate Mannich base ligands, synthesised by a metalloligand approach show antiferromagnetic coupling and significant catecholase and phenoxazinone synthase like activities.