A dual responsive bis-thiophene affixed thiosemicarbazide based chemosensor for colorimetrically Hg²⁺ and fluorometrically Cu²⁺ ions and their applications in live cell imaging

In this work, we developed a fast and straightforward colorimetric and photoluminescent chemosensor probe (P1), featuring bis-thiophene-thiosemicarbazide moieties as its signaling and binding unit. This probe exhibited rapid sensitivity to Hg²⁺ and Cu²⁺ ions in a semi-aqueous medium, resulting in distinct colorimetric and photoluminescent changes. In the presence of Cu²⁺, P1 displayed an impressive 50-fold increase in photoluminescence (PL) at 450 nm (with excitation at 365 nm). The probe P1 formed a 1:1 complex with Hg²⁺ and Cu²⁺ ions, featuring association constant values of 4.04 × 10⁴ M^-1 and 1.25 × 10³ M^-1, respectively. P1 has demonstrated its efficacy in the analysis of real samples, yielding promising results. Additionally, the probe successfully visualized copper ions on a mouse fibroblast cell line (NIH3T3), highlighting its potential as an intracellular probe for copper ion detection.