Supramolecular hydrogels of adenine: morphological, structural and rheological investigations

Abstract

Hydrogelation of adenine has been tested here with three isomers of benzene tricarboxylic acid. Upon cooling the homogeneous solution, adenine formed an instantaneous gel with one isomer while the other two did not. Hydrogels were thermoreversible in nature and were characterized with the help of ¹H-NMR, FE-SEM, TEM, AFM, PL, XRD, FT-IR and rheological analyses. ¹H-NMR studies showed the formation of molecular interaction between adenine and 1,3,5-benzenetricarboxylic acid (1,3,5-B) to form a supramolecular complex that led to the production of gel with a large volume of water. The morphological investigation of dried gel revealed the network of nanofibers that assembled further into belt-like thick fibers. FT-IR and X-ray studies showed that in the gel adenine and 1,3,5-B were mainly assembled through hydrogen bonding interactions into a layered structure, and the interlayer distance was 1.52 nm. The gel network formed as a result of controlled aggregation between adenine and 1,3,5-B was stable even after large deformation under rheological investigations.