Synthesis and Optoelectronic Features of Rhodamine-Triazole Dyads as Metallochromic Probes for Copper-Selective...

Rhodamine-based chromic materials have attracted significant interest owing to their cation recognition ability with high sensitivity. However, rhodamine chromophores with controllable sensing selectivity towards transition metal species are only at the advent. Herein, three triazole-conjugated rhodamine dyads with different peripheral substituents were synthesized. The key triazole precursors required for the desired chemistry were prepared by adopting our recently developed CTAB catalyzed mechano-click chemistry. Molecular properties derived from photophysics, electrochemistry and surface morphology of the synthesized dyads were analyzed. Furthermore, frontier molecular orbitals, electronic structure and secondary quantum chemical parameters of dyads were also compared. Screening of dyads for their sensing ability towards an array of alkali, alkaline and transition metal ions exhibited a noticeable naked-eye detection of Cu²⁺ ions and was confirmed by spectrophotometric titration. The specific binding mode of dyads as probable with Cu²⁺ over other metal ions attributes to the chemoselectivity.