A Library of Multipurpose Supramolecular Supergelators: Fabrication of Structured Silica, Porous Plastics, and Fluorescent Gels

Abstract

Supramolecular gels find applications in various fields. Usually, a specific gelator is useful only for a specific application. This one-gelator-one-application format is one factor that limits the usefulness of supramolecular gels. We report the synthesis of a library of gelators from a common core by using a click-chemistry approach. Thus, the click reaction of β-azido-4,6-O-benzylidene-galactopyranoside (1) with various alkynes gave 11 different gelators having varying gelation abilities. Whereas gelators having alkyl-chain substituents congealed alkanes and tetraethylorthosilicate (TEOS), the gelators having aromatic substituents congealed aromatic solvents. We exploited this difference in gelling behavior in the templated synthesis of silica rods and porous plastics. The styrene gel of gelator 2 j was polymerized, and the gelator was removed by washing to obtain porous polystyrene. The TEOS gel of gelator 2 b was polymerized to silica, and the gelator template was removed by calcination to give microstructured silica rods. We also developed fluorescent gelator 2 f by this method, which might find applications by virtue of its fluorescence in the assembled state.