Electrochemical and spectroscopic characterization of biologically important Schiff bases

Abstract

Redox behavior of two biologically important triazol derivatives i.e. (E)-1-((4H-1,2,4 triazol -4-ylimino) methyl)naphthalene-2-ol abbreviated as TMN and (E)-2-((4H-1,2,4 triazol -4-ylimino) methyl) 4-chlorophenol abbreviated as TMC was investigated on glassy carbon electrode surface. Experiments were carried over wide ranged concentration, pH, and temperature to evaluate various useful thermodynamic and kinetic parameters including ka, ΔG#, ΔH#, ΔS# along with Ea and diffusion co-efficient D. Thermodynamic data reveals that both compounds follow irreversible, pH dependent and diffusion-controlled oxidation processes which is both entropy and enthalpy opposed. Voltammetric studies help in determining the number of electrons and protons contributing in each oxidation reaction. The acid–base dissociation constant (pKa) value was found both by spectroscopic and electrochemical studies and the results obtained from both techniques were in good agreement. Computational studies give higher value of EHOMO, lower value of ELUMO, smaller orbital gap (ΔE) for TMN than TMB. Both the experimental and theoretical studies agree well in this regard and confirm that TMN is easily oxidizable compared to TMC. Sulforhodamine B assay demonstrated the non-cytotoxic character of the compounds up to 150 μM concentration. The present studies showed low cytotoxicity for these triazoles and their potential to be used as valuable compounds in biological applications.