• 1,8-diaminonaphthalene (DAN) reacted with various aldehydes to produce 2-substituted perimidines. • This work effectively offered a unique sensor prepared under greener solvent-free conditions. • The sensor showed exceptional sensitivity and high selectivity for Hg2+. • The molecule shows an equal orientation in the binding site of 5ACC enzyme. The detection of contaminated ions is a crucial concern with potential to mitigate environmental problems. Notably, 2-substituted perimidines exhibit promising efficacy in the context of environmental remediation applications. In this context, recyclable nanocatalyst SiO 2 -Pr-SO 3 H, 1,8-diaminonaphthalene (DAN) reacted with various aldehydes to produce 2-substituted perimidines. This work effectively offered a unique fluorescence from 2-(3-nitrophenyl)-2,3-dihydro-1 H -perimidine as a Hg2+ detector which was designed and prepared under greener solvent-free conditions. Intriguingly, the chemosensor responded to Hg2+ with a luminous reaction. The sensor showed exceptional sensitivity and high selectivity for Hg2+. It has been demonstrated that amino-containing chemical compounds can be exploited to create fluorescence ligands for finding Hg2+and may be adapted for other ions as well. [Display omitted] [ABSTRACT FROM AUTHOR]