Preparation of Large Conjugated Polybenzimidazole Fluorescent Materials and Their Application in Metal Ion Detection

A new type of conjugated polybenzimidazole (CPBI) was synthesized through a simple polycondensation reaction without metal catalysis, and N-alkylation modification was carried out to solve the problems of solubility and fluorescence properties. A series of nano-microsphere polymers CPBI(n) with large conjugation, good solubility, and strong fluorescence has been successfully used as “turn-off” fluorescent probes for the first time. The results show that, under suitable N-alkylation conditions, the obtained CPBI(n) can be used as a highly sensitive and selective fluorescent probe for the detection of Cu(2+) and Zn(2+) at the same time, and their detection limits are both nM levels. In addition, CPBI(2) can be designed as an ultra-sensitive IMPLICATION logic gate at the molecular level, cyclically detecting Cu(2+). With the test paper containing CPBI(2), easy and quick on-site detection can be achieved. This research provides a new idea for the brief synthesis of multifunctional materials.