Spectroscopic and Density Functional Studies on the Interaction of a Naphthalene Derivative with Anions

This article highlights the investigation of anion interactions and recognition abilities of naphthalene derivative, [(E)-1-(((4-nitrophenyl)imino)methyl)naphthalen-2-ol], (NIMO) by UV-visible spectroscopically and colorimetrically. NIMO shows selective recognition of F- ions colorimetrically, and a visual color change from yellow to pink is observed by the naked eye. The F- ions recognition is fully reversible in the presence of HSO4- ions. The limit of F- ions detection by NIMO could be possible down to 0.033 ppm-level. A paper strips-based test kit has been demonstrated to detect F- ions selectively by the naked eye, and a smartphone-based method for real sample analysis in the non-aqueous medium has also been demostrated. Spectroscopic behavior is well supported by pK(a) value calculation and DFT analysis, to find a correlation with receptor analyte interaction. The optical response of NIMO towards the accumulation of F- ions and, subsequently, HSO4- ions as chemical inputs provides an opportunity to construct INH and IMP molecular logic gates.