Reversible Heat-Set Organogel Based on Supramolecular Interactions of β-Cyclodextrin in N,N-Dimethylformamide

Abstract

This paper describes the first reversible, heat-set organogel based on the supramolecular interactions of beta-cyclodextrin (beta-CD). The gel was prepared by interaction of diphenylamine (DPA) with beta-CD and lithium chloride in N,N-dimethylformamide (DMF). In this gel system, DPA could be gelated in DMF as the temperature increased and then dissolved again as the temperature decreased. In the microscopic structure of gel, beta-CDs play a key role in the formation of nanorods and microfibers. Some important features of the gel were observed. (1) The system is a multicomponent solution, in which each of the four components is required for the organogelation property. (2) The system is a reversible, thermo-responsive organogel composed of small organic molecules. When the temperature is lower than T(gel), the gel transforms back into a solution. The reversible thermo-transition was confirmed by differential scanning calorimetry (DSC). The gel system is responsive to the concentration of LiCl. No gel was formed without LiCl. The stimuli responses of the system with other salts such as KCl and NaCl were weaker than with LiCl. (4) The system is responsive to the addition of guest molecules. The structures and sizes of the guest molecules could influence the gel formation. Generally, T(gel) decreased by adding guest molecules in the gel system, but some guest molecules, whose structures are exactly fitted to the cavity of CDs, could prevent gel formation. This work may provide new avenues in delivery of functional molecules as well as design of intelligent materials and biomaterials.

Rational Design of Heat‐Set and Specific‐Ion‐Responsive Supramolecular Hydrogels Based on the Hofmeister Effect

“…In one case, heat-set gelation is associated with an aggregation mechanism that relies on a temperature-triggered cis-to-trans molecular conversion. [22] Other examples include the conversion of a bolaamphiphile into a hydrogelator by means of a heat-induced retro Diels-Alder reaction, [23] the use of cyclodextrin based systems [24] or gelation associated with the thermal isomerisation of a metal coordination complex. [25] Results and Discussion Specific ion effects on the solution-to-gel equilibrium Hydrogels from compound 1 (Scheme 1) have been described by our group previously.…”

β‐Cyclodextrin: A Green and Efficient Supramolecular Catalyst for Organic Transformations

“…through supramolecular interaction. β‐CD also forms organogel like structures with substrate by supramolecular interaction in DMF . Host‐guest interaction of cyclodextrins were efficiently employed in constructing supramolecular gels ,.…”

Cu(II)-triggered release of paclitaxel from a supramolecular complex

“…XRD is often used to analyse the existence state of supramolecular species, especially for the compounds with crystalline structures (15,16). Typical peaks around 2u ¼ 58 and 138 of PTX were found both in the 1/PTX (although very weak diffractions) complex and physical mixture samples, which proves the existence of PTX in them.…”