ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis, characterization, physicochemical studies, and antibacterial evaluation of surfactant-based Schiff base transition metal complexes

Janak Adhikari, Ajaya Bhattarai, and Narendra Kumar Chaudhary

Department of Chemistry, Tribhuvan University, Biratnagar, Nepal

E-mail: chem_narendra@yahoo.com

Received: 4 September 2021  Accepted: 1 January 2022

Abstract:

The use of surfactants to enhance the efficacy of most conventional drugs is the recent progress of pharmacology. The rationale of this research is to design and develop surfactant incorporated drugs to overcome the challenges of antibiotic resistance. Herein, we report the synthesis of a novel surfactant-based Schiff base ligand (DDAP2C) from dodecylamine (DDA) and pyrrole-2-carboxaldehyde (P2C) and its two metal complexes, Ni-DDAP2C and Zn-DDAP2C. Characterization was performed by spectroscopic techniques such as ¹H and ¹³CNMR, electronic absorption spectral study, FT-IR, and ESI-mass spectrometry. They were further characterized by elemental microanalysis, powder X-ray diffraction, SEM-EDAX, and TGA/DTA analyses to obtain significant structural information. The conductance study revealed non-electrolytic nature. The critical micelle concentration (CMC) of the synthesized compounds was calculated using conductivity data. We extended our study to derive various surface properties and thermodynamic parameters from the CMC calculations. The popular Coats–Redfern equation was used to compute the kinetic and thermodynamic properties. Powder X-ray diffraction was performed to determine the crystallinity, crystallite size, microstrain, and dislocation density of the crystals. Geometry optimization was performed by running the MM2 job in CsChemOffice Ultra 16 programs and ArgusLab 4.0.1 version software. The antibacterial potency of the ligand and metal complexes was demonstrated by the standard Kirby–Bauer paper disk diffusion technique for E. coli, K. pneumoniae, P. aeruginosa, Enterococci, and S. aureus bacteria. Their actual potency against all pathogens was further assessed quantitatively by evaluating the minimum inhibitory concentration (MIC) tests and revealed a significant bacterial growth inhibition.

Keywords: Schiff base; Thermodynamic parameters; Surface properties; Antibacterial activities; Spectroscopic characterization

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02062-x

Chemical Papers 76 (4) 2549–2566 (2022)