Superhelical Self‐Assembly of Microcrystals from Cyclodipeptides

Expression of chirality at macroscopic scale through solution-processed bottom-up assembly is accompanied by the formation of complex superstructures. It undergoes complicated pathway including the hierarchical organization of molecular blocks in a spontaneous and ordered manner. Here we present a cyclodipeptide platform which delicately expresses chirality at the macroscopic level. Homochiral linear dipeptides bearing tyrosine and phenylglycine residue go through cyclization to afford cyclodipeptides, leading to the in situ reaction-induced aggregation into giant helices with ultra-high yields and phase purity. The pathway comprises formation of subunit microcrystals and the subsequent assembly through adhesion of favorable planes. The cyclodipeptide adopts a folded geometry that generates 2D hydrogen bonded networks differing from the typical 1D duplex hydrogen bonding of diketopiperazines skeletons. The assembly of subunit crystals driven by the hydrogen bonding undergoes dislocations mediated by the inherent chirality of cyclodipeptides. The bulky helices perform as matrices to accommodate cargoes to realize full spectrum luminescent colors with efficient chirality transfer and strong circularly polarized luminescence.