Conductometry of nano-sized zinc sulfate; synthesis and characterization of new hydrazone complexes: Conformational and in-vitro assay

Hydrazone derivative was used to prepare 1:1 M ratio with Cr(III) & Co(II) ions as well as 1:2 ratio with Zn (II) & Cd(II) ions. The ligand (H2L) coordinated as bidentate/tridentate via neutral/ monobasic towards the metal ions. This proposal depends on the size of metal ion and the conjugated anion in its salt used. The octahedral geometry of Cr(III) or Co(II) complex was confirmed via ligand field transition bands as well as the magnetic moment values. While, Cd(II) and Zn(II) geometries were assumed according to d 10 systematic forms and the mode of bonding was supported by H-1 NMR spectra. SEM, XRD, EDX and TGA were mainly used to detect surface morphology, particle-sizes, elemental percentages, and thermal stability, respectively. Molecular modeling was carried out to optimize the structural forms and then confirms the binding manner proposed from spectral studies. Consequently, the ligand showed a well distribution for C(8)-O(11) and C(13) = O(12) groups, which promotes their coordination easily without twisting or strain for the bonds. The electrostatic potential confirms nucleophilicity of O(11) and O(12) atoms, which improved after coordination with Cr(III) and Co(II) ions due to M -> L charge transfer. The dipole moment of the ligand (4.08 debye) predicts a distinguish biological activity for the ligand, while it is not expected for its complexes. Antimicrobial, antioxidant and cytotoxicity results of the ligand are extremely promising, which agreed perfectly with that expected from computations. Upon ZnSO4 solution prepared as a bulk or from nano-sized particles, in H2O or in mixed solvents (EtOH + H2O), the conductance parameters were estimated according to Fuoss-Hsia-Fernandez-Prini (FHFP) method. The limiting molar conductance commonly decreased by increasing ethanol percentage in solvent mixtures. In presence or absence of the ligand, the association constant, thermodynamic parameters and activation energy, were calculated in addition to complex formation constants and molar ratios [M:L]. (C) 2021 Elsevier B.V. All rights reserved.