Shape induced sorting: Via rim-to-rim complementarity in the formation of pillar[5, 6]arene-based supramolecular organogels

Two-component supramolecular organogels based on per-carboxylato- and per-amino pillar[6]arenes (2 and 4a-c) were prepared for the first time, and found to display very different characteristics as compared to those displayed by the corresponding pillar[5]arene derivatives (1 and 3a-c). Pillar[6]arenes derivatives, in contrast to pillar[5]arene derivatives, do not form organogels in alcoholic solutions and the formed gels in chlorinated solvents are, generally, more fragile. We analyzed the gelation ability of all the pairs between 1, 2, 3a-c and 4a-c, several three-component mixtures in 1:1:1 and 2:1:1 ratios, as well as four-component mixtures in ∼10:1 CDCl₃:DMSO_d6 solutions. The obtained results clearly show that shape complementarity is an important determinant of gel formation in these supramolecular pillar[n]arene-based organogels. We also found that shape directed molecular sorting occurs in the gelation process of these two-component supramolecular organogels.