Scrolling of Supramolecular Lamellae in the Hierarchical Self-Assembly of Fibrous Gels

Abstract

Gelation by small molecules is enormously topical in catalysis, nanomaterials, drug delivery, and pharmaceutical crystallization. The way in which gelators selforganize to give a 3D gel network is poorly understood. How does a system progress from a continuous pattern of supramolecular motifs to a network of fibers with well-defined morphologies? Why are gel fibers so homogeneous, and why do they form instead of crystals? This work shows, predictively, that gels arise by the scrolling of sheets with asymmetric surface structures.

Supramolecular Gelation as the First Stage in Ostwald’s Rule

“…[9][10] Formation of a smallmolecule supramolecular gel requires the organisation of molecules into a low-dimensional aggregate, such as a fibril 11 or scrolled sheet. 12 This behaviour is most commonly displayed by molecules whose non-covalent interactions are strongest in one direction, 11 such as ureas or amides which provide strong, directional NHꞏꞏꞏO=C hydrogen bonds. [13][14] It is well known that gelation and crystallisation are two closely related self-assembly processes.…”

Self‐Assembled Nanofibrilar Networks: Boosting Hydrogelation Efficiency by Replacement of a Pyridine Moiety by a Quinoline One

“…Studies that rationalize molecular gel formation provide ground for the preparation of materials with the desired properties. Insight into the molecular details of self‐assembled fiber formation have been reported recently . In the case of gels in organic solvents, solubility has been used to understand gelation efficiency .…”

High thermal stability, pH responsive organogels of 2H-benzo[d]1,2,3-triazole derivatives as pharmaceutical crystallization media

“…A mixture of 2-(3,5-bis(trifluoromethyl)phenyl)-4,7-dibromo-2Hbenzo[d] [1,2,3]triazole (2) (0.100 g, 0.200 mmol), the corresponding acetylene derivative (3) (0.4 mmol), DBU (0.061 g, 0.400 mmol), CuI (0.002 g, 0.010 mmol) and Pd-EncatTM TPP30 (0.018 g, 0.007 mmol) was charged under argon to a dried microwave vessel. CH3CN (1 mL) was added.…”

“…LMW organogelators usually form gels due to the presence of self-assembled fibres arising from intermolecular interactions such as hydrogen bonds, van der Waals forces and -stacking. The self-assembly of these LMW organogelators depends on the evolution of tertiary structure by processes such as scrolling, braiding and entanglement 3 via physical interactions involving aggregates that are sufficiently long-lived to give a structure that is permanent on the timescale of an analytical experiment. 4 Despite the fact that a plethora of LWM organogels have been reported and recent work has uncovered some trends in gelation tendency, 5 it is still difficult to predict the molecular structure of a promising gelator and in what solvents a gel may be formed.…”

“…bis(trifluoromethyl)phenyl)-4,7-bis((3,4,5tris(dodecyloxy)phenyl)ethynyl)-2H-benzo[d][1,2,3]triazole (4a): From 1,2,3-tris(dodecyloxy)-5-ethynylbenzene (3a) (0.266 g, 0.400 mmol), derivative 4a (0.201 g, 61%) was obtained as an orange solid by chromatography eluting with hexane/ethyl acetate (98/2). P.f: 156-158ºC 1.…”