Microwave-assisted synthesis of novel pyrazolyl sulfones and their antimicrobial evaluation and time-resolved photoluminescence studies

Abstract

This article reports an efficient and practical microwave-assisted MMPP-promoted synthesis of novel pyrazolyl sulfones from the corresponding 4-(alkyl/cycloalkylthio)-1H-pyrazoles. The reaction of 4-(alkyl/cycloalkylthio)-1H-pyrazoles with magnesium bis(monoperoxyphthalate)hexahydrate (MMPP) as an oxidizing agent afforded the corresponding 4-(alkyl/cycloalkylsulfonyl)-1,3-disubstituted-1H-pyrazoles in 85–95% yield. This method's benefits include its straightforward operation, simple workup, and use of an inexpensive, halogen-free MMPP oxidant that is easy to use and reasonably stable. All synthesized pyrazolyl sulfones were examined against bacterial and fungal strains, and notable antimicrobial activity was demonstrated by a few of the compounds. In order to investigate the prospect of connecting compounds with the highest yield and antimicrobial activity with their opto-electronic properties, time-resolved photoluminescence investigations for compounds 5a, 5b, and 5d were conducted. The tunable spectrum was observed in the micro-second time domain in all three cases, with fluorescent lifetime found higher in the compound having methyl group, intermediate with phenyl group, and lowest with the p-nitrophenyl group. Our procedures will encourage additional research into the valuable properties of pyrazolyl sulfones now that they are widely available with the structural complexity illustrated here.

GRAPHICAL ABSTRACT

KEYWORDS:

• Microwave
• pyrazolyl sulfones
• antimicrobial
• Vilsmeier-Haack reagent
• photoluminescence

Acknowledgments

The authors acknowledge the financial support and laboratory facilities provided by Indira Gandhi University, Meerpur, Rewari, Haryana, and the Department of Chemistry at Lingaya's Vidyapeeth, Faridabad. The authors express their gratitude to Panjab University, Chandigarh's Regional Sophisticated Instrumentation Centre for capturing the analytical data used in the study.

Disclosure statement

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