Single Component-Uncomplicated Self-Assembly: Conformational Modulation to Regulate Chirality Transformation in Perylene Bisimide Superhelical Assemblies in Aqueous Media.
Abstract
The progression of supramolecular chirality in synthetic helical assemblies relates directly with the structure of building block, consequently, the generation of right- and left-handed helical assemblies from single component system is highly challenging. Herein, we demonstrate the coupling of designed PBI-Ind building block and solvent to direct the chirality progression in initially formed metastable helical assemblies in DMSO/THF toward opposite supramolecular helicities by subtle regulation of microenvironment. The combined experimental results suggest generation of higher order right-handed superhelical assemblies upon aging (accelerated by heating-cooling cycle) under strong hydrophobic conditions while weakening of hydrophobic effect led to the generation of superhelical assemblies with opposite handedness. Interestingly, identical growth pathways were followed every time during self-assembly process yet the regulated hydrophobic effect controlled the choice of PBI-Ind molecules to engage in hydrogen bonding interactions among themselves and/or with proton acceptor good cosolvent which served as the deciding factor to direct the chiral orientation of supramolecular assemblies.