Aggregation and supramolecular chirality of 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin on an achiral poly(2-(dimethylamino)ethyl methylacrylate)-grafted ethylene-vinyl alcohol membrane

Abstract

5,10,15,20-Tetrakis-(4-sulfonatophenyl)-porphyrin (TPPS) can be adsorbed on a poly(2-(dimethylamino)ethyl methylacrylate)-grafted ethylene-vinyl alcohol (PDMAEMA-grafted EVAL) membrane based on electrostatic interaction. H- and J-aggregation of TPPS on the membrane was investigated. A higher adsorption amount of TPPS and a higher grafting degree of the membrane helped to form J-aggregates. Two types of chiral J-aggregates were achieved in the presence of chiral tryptophan. The pending-type chiral aggregates showed single CD bands and rod-like morphology; and the wrapping-type aggregates exhibited CD couplets and dispersed spherical morphology. The wrapping chirality can be cyclically “switched off–on” by cycling the pH from 1.0–7.0–1.0, and the pending chirality would transform into the wrapping one after such a pH cycle. The aggregates of TPPS on the achiral membrane expressed the chiral information of the excess enantiomer, and the supramolecular chirality can be imprinted via strong electrostatic interaction with PDMAEMA chains even after removal of the chiral template.