A pyridyl azo-based progelator 1 has been designed and synthesized for selective detection of Hg2+ and Ag+ ions in sol- gel media. Compound 1 acts as nongelator in DMSO-H2O (1:1, v/v) while its aldehyde-counterpart 3 forms stable gel under identical conditions. The specific Hg2+-induced deprotection of the thioacetal functionality in 1 results in in-situ formation of the precursor aldehyde 3 and thereby induces sol-to-gel transformation in DMSO-H2O (1:1, v/v). Gelation is also observed in the presence of Ag+ ion. Interestingly, the gelation modes of 1 in the presence of Hg2+ and Ag+ ions are different. The Hg2+-induced gelation involves dosimetric sensing while the Ag+-induced gelation involves simple metal-ligand non- covalent interaction, as established by using different chelating agents and spectroscopic techniques. The design of metal- responsive low molecular weight gelators (LMWGs) involving protection/deprotection of functional groups in gelator struc- ture is rarely investigated in the literature and hence draws attention.
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