Conformational control of bis-urea self-assembled supramolecular pH switchable low-molecular-weight hydrogelators

Abstract

We report the synthesis and investigation into the structure-property relationships of eight different low molecular weight hydrogelators based on a bisaromatic urea core unit, all of which form gels as the pH of the solution is lowered. The low molecular weight hydrogelators are functionalized with carboxylic acid moieties on one aromatic ring, and the other aromatic ring features a nitro functional group either in the meta-or paraposition relative to the urea linkage. Ortho-methyl substituents were installed on the aromatic rings to enforce a non-coplanar arrangement between the phenyl and urea moieties. Gel formation was triggered by the addition of a mineral acid or the ring-opening hydrolysis of glucono-δ-lactone. The low molecular weight hydrogelators were studied by a variety of analytical techniques, including NMR spectroscopy and rheology. In addition, their ability to uptake a dye, methylene blue, was determined by UV-vis spectroscopy.

Iron‐Catalyzed Intermolecular C−H Amination Assisted by an Isolated Iron‐Imido Radical Intermediate

“…Supporting Information contains complete experimental and computational details and characterization of new molecules including X‐ray crystal structures. The authors have cited additional references within the Supporting Information [81–112] …”