Aggregation enhanced emission (AEE) in organic salt: A structure-property correlation based on single crystal studies

Abstract

Salt formation has been shown as a simple strategy to induce aggregated induced emission or aggregated enhanced emission in primary ammonium salts derived from 9-anthracene carboxylic acid, 1-pyrene carboxylic acid, 3-coumarin carboxylic acid and histamine. All the salts displayed enhanced fluorescence in their solid state compared to that in their solution state. Single crystal structure of the salt of 9-anthracene carboxylic acid i.e., His-anthracene revealed that restricted intramolecular rotation of the fluorphoric moiety (anthracene) was responsible for such radiative pathway leading to enhanced emission.