Constructing unconventional fluorescent molecules by imidazoline ring and its salt of carboxylic acid and their application

Abstract

Recently, fluorescent compounds without conventional chromophores have attracted considerable attention. One of the effective strategies for forming unconventional fluorescent compounds is to figure out the unconventional chromophores, then to develop more excellent fluorescent molecules with these structures. The imidazoline ring is one of the unconventional chromophores exhibiting fluorescence because of its planarity and rigidity. The imidazoline ring was used as the raw material for constructing unconventional fluorescent molecules in this paper. When acetic acid was introduced into imidazoline (2-MZ) to form 2-methylimidazoline acetate (2-MZA), the fluorescence significantly increased. Furthermore, by analyzing the change in fluorescence during the crystal and solution states of 2-MZ and 2-MZA, the result demonstrated the intermolecular interaction, that is, clusters of aggregated oxygen atoms influenced molecular fluorescence. Moreover, we explored the applications of 2-MZ and its ionic liquid in metal ion recognition, pH sensing, and fluorescent staining in living HeLa cells.