A Unique Temperature‐Induced Reverse Supramolecular Chirality‐Assisted Gel‐to‐Gel Transition

• DOI: 10.1002/marc.202400018
• Publication Date: 2024-03-04T22:59:30Z
• Authors: Dinesh Kumar Dura...; Samala Murali Moh...; Puchalapalli Saveri; Abhijit P. Deshpande; Ganesh Shanmugam
• Keywords: Molecular Structure; Macromolecular Substances; Temperature; Tyrosine; Thermodynamics; Hydrogels; Stereoisomerism; 02 engineering and technology; 0210 nano-technology; Gels; Phase Transition

AbstractSupramolecular hydrogels typically undergo a gel‐to‐sol transition with heat, as intermolecular interactions within the gel weaken. Although gel‐to‐gel transitions during heating are rare, they may occur due to minor rearrangements caused by thermal forces in the supramolecular self‐assembled structure. Here, an unprecedented temperature‐induced gel‐to‐gel transition assisted by supramolecular chiral inversion in a hydrogel system is presented. The transition results from a left‐handed M‐type helix to a right‐handed P‐type helix, attributed to the π‐system‐conjugated amino acid, l‐Tyrosine (Fm‐ l‐Tyr). Upon solvent dilution, Fm‐l‐Tyr induces translucent hydrogel formed by entangled fibers with a kinetically stable left‐handed M‐type supramolecular helix. At 70 °C, hydrogel transforms into an opaque gel with a reverse supramolecular chirality yielding a thermodynamically stable right‐handed P‐type helix. Supramolecular chiral inversion is substantiated by two chiroptical methods. This unique gel‐to‐gel transition, accompanied by chiral inversion, is anticipated to attract attention, especially for applications sensitive to chirality.