Supramolecular chiral helical ribbons of tetraphenylethylene-appended naphthalenediimide controlled by solvent and induced by L- and D-alanine spacers

Abstract

Naphthalenediimide-tetraphenylethylene with alanine spacer (coded as: NDI-(Ala-TPE) sub(2)) were synthesized to study the influence of the chirality of amino acid spacer on its self-assemblies. Here we particularly show that NDI-Ala-TPE bearing L-alanine gives left-handed (M-type) helical superstructure, while D-alanine produces right-handed (P-type) helical ribbons in THF:H sub(2) O at 40:60% v/v ratios. However, particular aggregates were observed at higher 20:80% v/v ratios. Circular dichroism is used to characterise induction of chirality and the handedness of the helical superstructures, and the microstruture of the self-assembled materials was visualised using scanning electron microscopy and DLS confirm formation of particular aggregates in solution.