Circularly Polarized Luminescence and Tunable Helical Assemblies of Aggregation-Induced Emission Amphiphilic Polytriazole Carrying Chiral L-Phenylalanine Pendants

Chiral polytriazole derivatives carrying terapheny-lethene (TPE) and L-phenylalanine were synthesized, which had a TPE backbone and a chiral L-phenylalanine pendant in common, but with the phenylalanine pendant in ester protected and deprotected carboxylic acid form, respectively. The deprotected carboxylic acid form was further added with chiral (1S,2S)- and (1R,2R)-cyclohexane-1,2-diamine (Chxn) to form a host-guest polymer system, respectively. The combination of luminescence and chirality in polymers was successful to endow them with CD, AIE, and CPL properties and the ability to self-assemble. The deprotected P(TPE-Phenylalanine) with (1S,2S)-Chxn added showed the best optical performance and formed the most regular helical assemblies, followed by the deprotected P(TPE-Phenyl-alanine), P(TPE-Phenylalanine), and (1R,2R)-Chxn added deprotected P(TPE-Phenylalanine). The chiral pendant groups helped chirality transfer from the side chain to the main chain by forming hydrogen bonding. Subtle changes in the pendant structure led to diverse intermolecular interactions, which caused significant changes in the optical properties and chiral self-assemblies of the polymers. With the pendant hydrolyzing from the ester to acid form, hydrogen bonding was considerably strengthened; with (1S,2S)-Chxn added, hydrogen bonding was further enhanced.