A novel fluorescent sensor based on imidazo[1,2-a]pyridine for Zn²⁺

A novel chemosensor L1 for the detection of Zn²⁺ based on an imidazo[1,2-a]pyridine in C₂H₅OH-H₂O (9:1, v/v) buffer solution was designed and synthesized. L1 showed a significant fluorescence enhancement in the presence of Zn²⁺ over other competitive metal ions with a limit of detection of 6.8 × 10^-8 M. Upon the addition of Zn²⁺, the resulting complex L1-Zn²⁺ could induce bathochromic shifts both in absorption and emission bands due to the intramolecular charge transfer process (ICT). The reason for fluorescence enhancement and color changes of L1 towards Zn²⁺ was demonstrated by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations with 6-31G(d) basis sets using a suite of Gaussian 03 programs.