Manganese(II) complexes of thiophenyl imino-ligand with synergistic behavior in biological systems, ct-DNA interactions, and catalytic oxidative performance of benzyl alcohol

Abstract

Considering a facile synthesis and high coordination ability of substituted imines, a condensation reaction between 2-aminobenzenethiol and thiophene-2-carbaldehyde produced an interesting derivative of the thiophenyl imine ligand (HLSNS). The coordination feature of HLSNS with Mn(II) ions was studied in 1 and 2: 1 M ratios, leading to the formation of two different structural complexes, MnLSNSCl and Mn(LSNS)₂, respectively. Their chemical structures were validated by several suitable techniques, covering also the micro-elemental analyses, thermogravimetric evaluation, magnetic properties, and conductivity behaviors. Biologically, the inhibitory action of HLSNS (the free ligand) and its Mn(II)-chelating reagents on the growth power of three common bacterial and fungal strains, beside three established human cancer cell lines, were evaluated in relation to the presented Mn(II) ion and the structural influences of MnLSNSCl and Mn(LSNS)₂ compared to their free ligand (HLSNS). The antimicrobial and anticancer behavior was estimated based on the measured inhibitory zone (mm) and the half-effective inhibitory concentrations (IC₅₀, mM). Discovering the pivotal influence of Mn(II) ions and their ratios in the two chelates on the binding strength to the calf thymus DNA (ct-DNA), which reported by the alterations in viscosity and spectrophotometric properties of DNA. The ct-DNA interaction strength was built on the values of binding constants, Gibb’s free energy, and chromism modes, confirming also the interaction modes. For the catalytic potential testing, both MnLSNSCl and Mn(LSNS)₂ were employed for the oxidative progressing of benzyl alcohol using hydrogen peroxide in a homogenous phase at 80 °C. Both catalysts exhibited superior catalytic oxidative activity. The yield percentage of selective benzaldehyde using MnLSNSCl and Mn(LSNS)₂ was 90 % after 4 h, and 84 % after 5 h, respectively. The discrepancy in the optimum activity for both catalysts pertained to the differences in their molecular structures, which helped to assume a convenient mechanism.