Synthesis and fluorescence characteristics of selective ratiometric fluorescent sensors for silver ions based on 3-indolyl-4-indazolyl maleimide derivatives

摘要

Selective ratiometric fluorescent sensor b for detection of silver ions and its counterparts (sensor a and c) were efficiently synthesized based on 3-indolyl-4-indazolyl maleimide, and their photophysical properties and activities towards metal ions were examined. The experimental results were verified by density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The results demonstrated that sensor b could selectively and sensitively recognize Ag+ compared with other competing metal ions in tetrahydrofuran (THF). It probably forms a 1:1 complex with Ag+, displaying a 52-nm bathochromic shift of the fluorescence emission spectrum. Moreover, the binding mechanism was investigated using binding stoichiometry titration and H-1, C-13 nuclear magnetic resonance (NMR).