Acyclic Polyorganochalcogenoethers and their Functional Activities: Synthesis of Sterically Encumbered Hexakis(alkylchalcogenomethyl)benzenes [(RECH2)6C6] [E=S or Se] and their Potential as Selective Ionophores for Hg²⁺ Ions

Introduction: An efficient synthesis of hexakis(alkylthio/selenomethyl)benzenes [(RSCH2)6C6 and (RSeCH2)6C6] (1-14) (where, R= ⁿPr, ⁱPr, ⁿBu, ⁱBu, ^sBu, ^tBu, ⁿPent, ⁱPent, and 2- Methyl-1-butyl) by the reaction of hexakis(bromomethyl)benzene with alkylthio or alkylseleno (RS- /RSe-) anions is demonstrated. Methods: They have been characterized by physicochemical and spectroscopic methods, including single-crystal X-ray crystallography. The balances between multiple [C(sp³)-H…S] or [C(sp³)-H…Se] intramolecular interactions in these species appear to decide their stability. Preliminary spectroscopic (UV-vis. and fluorescence) data on the behavior of alkylchalcogeno substituted hexa-benzenes in solution revealed their potential as ion-sensing species and function as highly selective ionophores for Ag⁺ and Hg2⁺ ions recognition. Results: In situ, (Hg-S) and (Hg-Se) bond formation on interaction with the chosen hexa-species (2 and 10) and Hg2⁺ cation revealed a unique ‘turn-off’ or ‘turn-on’ emissive behavior, and these functions act as reporting fluorescent tools for Hg2⁺ quantification without use of any external fluorophore. Conclusion: The present study describes an efficient and simple route for the synthesis of sterically encumbered poly-alkylthio/seleno benzenes in high purity and good yields.