A Novel Chemosensor for Selective Detection of L-Arginine and L-Cysteine via Macroscopic Sol-Gel Transition

To develop chemosensors for biomolecule recognition, a multi stimuli responsive supramolecular gelator, [(E)-4-((4-(benzyloxy)phenyl)diazenyl)benzaldehyde], comprised of azo and formyl units, was designed and synthesized from readily available starting materials. The gelator was found to be capable of forming gels in light alcohols and alcohol/water mixtures at low concentrations (0.7-1.5 g/100 mL). The gel rheological analyses showed the dominance of storage modulus (G ') values (ca 5000 Pa) within the range of analysis, confirming the gel stiffness. The xerogel scanning electron microscopy (SEM) studies showed a flake-like pattern of thin sheets. Our investigations on the gelator sensing abilities revealed that, in addition to the photo-responsive function due to the presence of azo moiety, its ethanol/water gel exhibited excellent ability to detect l-arginine among 19 various amino acids, via gel to sol transition and colour change. Furthermore, the gelator could successfully recognize l-cysteine among 19 amino acids, through macroscopic sol to gel transition and colour change of its alkaline methanolic solution. Moreover, the photo- and chemo-responsive functions of the gelator were demonstrated as two combinational logic gates.

Automated summary

A multi stimuli responsive supramolecular gelator was designed and synthesized, which could form gels in light alcohols and alcohol/water mixtures. It was found to have excellent biomolecule recognition abilities, detecting specific amino acids through gel to sol transition and color change.