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

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.