Anions play an important role in biology, industry, and environment. Compounds that have the capability of binding anions may find applications in the treatment of various diseases and disorders, in removal of harmful anions from drinking water and much more. Tetrazolones possess an N-H moiety that offers the potential to interact with negatively charged species through hydrogen bonding, however, the anion-binding ability of tetrazolones remains largely unexplored. In this study, a variety of substituted aryl tetrazolones were synthesized by reacting the isocyanates with trimethylsilyl azide under reflux for 24 hours. The interaction of synthesized tetrazolones with anions such as acetate, hydrogen sulfate, bromide, nitrate and chloride was investigated in acetonitrile by UV and NMR spectroscopy. Significant UV changes were observed upon addition of the acetate anion to the solution of tetrazolone in MeCN. Our studies showed that tetrazolones underwent an acid-base reaction with the acetate anion owing to its higher basicity. A downfield shift in the NMR spectrum was observed for the acetate protons in the presence of tetrazolones, indicative of proton transfer. To gain further support for deprotonation, UV titration of tetrazolones with triethylamine was carried out which showed similar spectroscopic changes as observed in case of the acetate addition. Further, the UV and NMR spectroscopic titrations indicated that tetrazolones interact weakly with Cl-, Br-, NO3-, and HSO4-, most likely through hydrogen bonding. Job’s plots were employed to determine stoichiometry of interaction of these anions with tetrazolones.

Investigating the interaction of aryl tetrazolones with anions

255th National Meeting (2018)

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