Triazole appended BODIPY–piperazine conjugates and their efficacy toward mercury sensing

Abstract

An expeditious synthesis of new click reaction-based BODIPY–piperazine conjugates separated by alkyl spacers (4–7) has been described. The compounds under investigation have been thoroughly characterized by various physicochemical techniques viz., elemental analyses, IR, HRMS, NMR (¹H, ¹³C, ¹¹B and ¹⁹F), electronic absorption, emission and theoretical studies. The comparative sensing abilities of 4–7 toward a range of metal ions have been investigated by various methods. Among these compounds, only 7 exhibited appreciable selectivity towards Hg²⁺, while the others remained inactive in the presence of various metal ions. Binding constant and Job's plot analysis indicated 1 : 1 stoichiometry between 7 and Hg²⁺. HRMS data and theoretical studies undoubtedly indicated the formation of a 7·Hg²⁺ complex and interaction of Hg²⁺ with the probe via nitrogen atoms in the piperazine and triazole units.