Vicinal Solvent Effect on Supramolecular Gelation: Alcohol Controlled Topochemical Reaction and the Toruloid Nanostructure

Abstract

Although solvent is the major component of the gel, it still remains unclear how the solvent molecules take part in the formation of the gel nanostructures in many gels. In this study it was observed that the vicinal effect on gel formation as well as their nanostructures, that is, the vicinal solvent molecules to the gelator, determine the molecular packing and their subsequent structures and properties. A naphthylacryl-conjugated L-glutamide gelator was found to form organogels in various solvents and nanofiber structures. While the nanofibers from other solvents could not show any further reaction, the gel from the alcohol could undergo topochemical [2+2] cycloaddition under photoirradiation and resulted in toruloid nanostructures. Various pure alcohol solvents from methanol to pentanol were found to show a similar property. Interestingly, switching from a single alcohol solvent to mixed solvents of alcohol with miscible or immiscible non-alcohol solvents could still cause the same change, showing the vicinal effect of alcohol on controlling the molecular packing as well as the structural transformation. More interestingly, when nanofiber xerogel, obtained from non-alcohol solvents, was exposed to alcohol vapor, the nanofiber was transferred into nanotoruloid. These results provide a new insight into the gelator-solvent interaction in soft gels.

Photomodulated Morphologies in Halogen Bond–Driven Assembly during Gel–Sol Transition

“…These results indicated that the halogen bond between pyridine group in Azopy‐C 10 and TFDIB was of great importance for gelation. Notably, the critical gelation concentration of Azopy‐C 10 •TFDIB in acetonitrile (2 wt%) was lower than that in ethanol (4 wt%) . This result would be attributed to the replacement of halogen bond by hydrogen bond between ethanol and pyridine group.…”

Photochemical Reactions in Supramolecular Assemblies of Gels: Dimerizations and Polymerizations via Pericyclic Reactions

“…Wang et al . reported that a naphthylacryl‐conjugated L‐glutamide ( 4 ) forms organogel in non‐alcoholic solvents as well as alcoholic solvents . However, it was found that the gels obtained from alcoholic solvents undergo topochemical [2+2] reaction upon photoirradiation (Figure a), while the gels obtained from non‐alcoholic solvents were found to be photostable.…”

“…Generally, the gel structures were deduced in many cases from the solid state structures of the gelators or powder patterns of the xerogels. It was proven by us, and others, no such one‐to‐one correlation exists between gel‐xerogel or gel‐solid state in terms of their supramolecular structures. In a way, the geometry of the product formed is anticipated to give way to deduce the geometry of supramolecular assemblies in gel or xerogels.…”

“…[37,38] Wang et al reported that a naphthylacryl-conjugated L-glutamide (4) forms organogel in non-alcoholic solvents as well as alcoholic solvents. [33] However, it was found that the gels obtained from alcoholic solvents undergo topochemical [2 + 2] reaction upon photoirradiation ( Figure 3a), while the gels obtained from nonalcoholic solvents were found to be photostable. Notably, the irradiation of gel was found to transform the morphology of 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 the nano-fibrous gel to toruloid nanostructures.…”

A rechargeable self-healing safety fuel gel

“…14 The supramolecular gels have potential applications including sensing of biomolecules and ions, light-harvesting systems, [15][16][17][18][19] catalysis, 20 optoelectronic devices, 21 and as media for cell culture, tissue engineering and targeted drug delivery. [22][23][24][25][26][27][28][29] Many organic motifs such as steroids, 30 peptides, [31][32][33][34] ureas and amides, [35][36][37][38][39][40] sugars, 41 dendrimers, 42,43 and p-conjugated molecules 44,45 have been designed and developed as gelatos. But, most of these organic gelator molecules need to be synthesized by tedious procedures.…”