A unique covalently linked pyridine-tetrathiafulvalene as a stimuli-sensitive sensor for the specific, selective optical and electrochemical detection of Pb2+

Abstract

An efficient and new synthetic strategy was highlighted to target a covalently linked pyridine-tetrathiafulvalene (Py-TTF) dyad. As evidenced by colorimetric tests, UV-vis analyses and cyclic voltammetry measurements, the Py-TTF dyad shows a specific and a selective recognition of Pb²⁺ ions over other metal cations. A drastic and unique variation of color, specific changes of the intramolecular charge transfer band of the Py-TTF dyad, and an unchanged oxidation potential E_ox2 compared to E_ox1 were observed in the presence of Pb²⁺ ions. The direct linkage between Py and TTF units through a covalent carbon–carbon bond ensures optimal electronic communication between both units, thus allowing an optical and electrochemical response to Pb²⁺ in organic solution with high selectivity and specificity compared to other metal cation species M^X+ (M^X+ = Fe²⁺, Mg²⁺, Pb²⁺, Na⁺, Zn²⁺, Ag⁺, Cd²⁺, and Cs⁺).