Influence of Odd and Even Alkyl Chains on Supramolecular Nanoarchitecture via Self-Assembly of Tetraphenylethylene-Based AIEgens

The Tetraphenylethylene (TPE) based dumbbell shaped molecules TPE-Pi, TPE-Su, TPE-Az, and TPE-Se were synthesised bearing odd-even alkyl chains containing 7, 8, 9 and 10 carbons respectively. These molecules reveal typical Aggregation Induced Emission (AIE) behaviour. The influence of the odd or even alkyl chain length was shown by studying the morphology of self-assembled nanostructures formed in a range of tetrahydrofuran (THF)/water solvent systems. For example, with a water fraction of 80%, TPE derivatives with odd alkyl chains (TPE-Pi and TPE-Az) self-assembled into nanosphere structures, while TPE-Su with 8 alkyl chains formed microbelts and TPE-Se with 10 alkyl chains aggregated into flower-like superstructures. These TPE derivatives also revealed interesting mechanochromic properties upon grinding, fuming and heating, which reveal the importance of molecular stacking in the crystal structure to the luminescent properties of the aggregates .The mechanochromic properties of TPE-Pi, TPE-Su, and TPE-Az were also demonstrated by the process of grounding, fuming, and heating