Synthesis, characterization, theoretical studies and antimicrobial activity of novel 1-(2‑hydroxy-4-propoxy-3-propylphenyl)ethanones bearing thiotetrazole

Abstract

We report herein a joint experimental and theoretical investigation on the novel 1-(2-hydroxy-4-propoxy-3-propylphenyl)ethanone bearing 1-propyl-1H-tetrazol-5-thiol and 2-propyl-2H-tetrazole-5-thiol pharmacophores. In the experimental studies, 1-[4-(3-((1-propyl-1H-tetrazol-5-yl)thio)propoxy)-2-hydroxy-3-propylphenyl]ethanone and 1-[4-(3-((2-propyl-2H-tetrazol-5-yl)thio)propoxy)-2-hydroxy-3-propylphenyl]ethanone were synthesized and characterized by ATR-FTIR, 1H NMR, 13C-APT, and HRMS. In the theoretical studies, the most stable conformations, vibrational and NMR spectra of these compounds were predicted by Quantum chemical calculations. Quantum chemical calculations were performed using the B3LYP functional with 3–21 G, and 6–311++G(d,p) basis sets. All quantum chemical calculations were utilized Gaussian 16 software. While torsional barriers of the compounds were determined by B3LYP/ 3–21 G, their geometry optimizations were performed by B3LYP functional with 3–21 G, and 6–311++G(d,p) basis sets. The harmonic vibrational frequencies, potential energy distribution (PED) and infrared intensities were predicted using the B3LYP/6–311++G(d,p). Theoretically predicted vibrational frequencies were compared with experimental results. Predicted NMR chemical shifts were obtained by the GIAO method using the B3LYP/6–311++G(d,p). The 1H and 13C experimental chemical shifts are consistent with the theoretical NMR chemical shift values. Antimicrobial activities of the title compounds were investigated against five bacterial strains (Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, Stenotrophomonas maltophilia) and two fungal strains (Candida albicans, Aspergillus fumigatus). The compounds showed good antimicrobial activity and inhibited all tested bacteria and fungi.