Mono-cyclopentyl substituted [1,3,4]thiadiazole thione tautomer: study of the spectroscopic, geometric, thermal, and biological properties

Abstract

Regarding the importance of thiol-thione tautomer structure and the existence of hydrogen bonding in thione tautomer structure and its effect on geometric, physicochemical, and biological properties, mono-cyclopentyl-substituted bismuthiol was synthesized via a telescopic process in a green medium. The pure product was characterized by physical and spectroscopic techniques. The suitable crystals for single crystal study were obtained after trying different solvents and mixed solvents, and long clear needle-like crystals could be isolated from a mixture of n-hexane and ethyl acetate (volume ratio of 8:2). The FTIR spectra of bismuthiol, 2,5-bis-cyclopentylsulfanyl-[1,3,4]thiadiazole, and 5-cyclopentylsulfanyl-3H-[1,3,4]thiadiazole-2-thione were studied to define the characteristic wavenumbers of thiol and thione structures. A possible hyper-conjugative interaction between the S–H and π bond of C=N, the existence of C=S and C–N–H. and stability of thione structure was demonstrated for the new product, which supports our prediction of thione or thiol structure using the study of IR spectra. Furthermore, the influence of change in 1,3,4-thiadiazol ring and the presence N–H functional group of thione structure on the transition phases and thermal stability of bismuthiol, bis-cyclopentyl-substituted, and mono-cyclopentyl-substituted bismuthiol were investigated using TGA/DTA and DSC profile analysis. The SwissADME tool was employed to predict the biocheminformatic information of bismuthiol, bis- and mono-cyclopentyl-substituted bismuthiols, which displayed high potential of all 1,3,4-thiadizole derivatives in pharmaceutical and medicine areas. Finally, an in vitro antibacterial activity of the mono- and bis-cyclopentyl substituted bismuthiol against the gram-negative (Escherichia coli ATCC 25922) and gram-positive (Staphylococcus aureus ATCC 25923) bacterial species was conducted by the disk diffusion method with cefazolin as a blank antibiotic. The results showed superior antibacterial efficiency of both derivatives.

GRAPHICAL ABSTRACT

KEYWORDS:

• Organosulfur
• crystal structure
• structure–activity relationship
• thermal behavior
• biological activity

Acknowledgments

The authors are also thankful to Dr. Amalina Mohd Tajuddin for conducting crystallography, and grateful to all staff members in the Analytical and Testing Center of Universiti Malaya for their partial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contributions

Nurul Fatimah Abdul Basir: Methodology, Investigation, Formal analysis, Data collection; Mahta Ghafarikhaligh: Methodology, Investigation, Formal analysis, Data collection; Mohd Rafie Johan: Supervision; Nader Ghaffari Khaligh: Conceptualization, Data curation, Validation, Resources, Supervision, Writing-original draft, Writing-review & editing.

Additional information

Funding

The authors used a Research Grant of [grant number IIRG004A-2022FNW] from the Ministry of Higher Education (MOHE), Malaysia, and the grant of [IF008-2023] from Nippon Sheet Glass Foundation for Materials Science and Engineering, Japan to conduct this work.