Multi-responsive supramolecular gel based on uracil as latent fingerprints imaging material

Abstract

Four fluorescent low molecular weight gelators based on benzoxazole or benzothiazole functionalized pyrimidine were designed and synthesized. The ability of the target was tested, and all compounds could form stable supramolecular gels in an alcohol/water mixture and its fluorescence increased during gel formation. Photophysical spectra during gel formation, SEM, XRD, FT-IR study suggested that the self-assembly was driven by hydrogen bonding, van der Waals forces and weak π-π interaction. Interestingly, the gel collapsed after being illuminated by 365 nm UV light and 1H NMR of the gel before and after illumination proved that the [2 + 2]-cycloaddition between the double bond of pyrimidine was responsible for the light response. Furthermore, the fluorescent of xerogel film could be quenched by volatile acids while the fluorescent of the solution was enhanced after acid was added. The different phenomena were discussed. The nano-fiber assembled via gel formation could be used as fluorescent imaging material of latent fingerprints.