Bimodal fluorescence signaling based on control of the excited-state conformational twisting and the ground-state protonation processes

摘要

Amino-based fluoroionophores 1 and 2 can selectively sense alkaline earth metal ions in MeCN under both neutral and acidic conditions by different signaling mechanisms.The fluoroionophoric behavior for the neutral probes is characterized by an 'off-on' photoinduced electron transfer (PET)-like fluorescence intensity response due to a switching from a twisted internal charge transfer (TICT) to a planar internal charge transfer (PICT) state.For the protonated probes (i.e.,1/H+ and 2/H+),the fluorescing species is the localized stilbene fluorophores,but dual fluorescence is induced upon metal-ion recognition through a deprotonation process.