In this paper, an efficient and novel 1,3-bis(2-pyridylimino)-4,7-dihydroxyisoinndole scaffold-based two-site fluorescent probe 1,3-bis(2-pyridylimino)-4,7-phenylene diacrylate isoindole (BPI-AC) for the sensing of cysteine (Cys) has been designed and synthesized. We have studied the chemical structure and its fluorescent properties for the novel fluorescent probe with double recognition group by means of theoretical calculations and experimental measurements, which were carried out using density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations and experiments on organic chemical synthesis. Firstly, geometries have been recorded for the fluorescent probe. Theoretical research parameters including spectroscopic parameters, molecular orbitals, reaction sites and energy barrier Delta were obtained by fitting the electron density in a multiparticle system. Additionally, the spectral characteristics, selectivity and anti-interference performance of the probe were systematically investigated and verified by in vitro experiments. The experimental results showed that by using this probe, it was possible to quantitatively detect Cys in 1% dimethyl sulfoxide-containing water solution (pH 7.4). Super large Stokes shift (265 nm) endowed the probe low background signal. Finally, according to our theoretical calculations and the available experimental data, the probe BPI-AC with dual recognition sites could distinguish the biothiols with similar structure through series recognition reaction, and the Stokes shift was large, realizing the efficient detection of Cys specificity.
