Title
Binding selectivity of vitamin K3 based chemosensors towards nickel(II) and copper(II) metal ions
Author
Amit Patil, Dipali N. Lande, Archana Nalkar, Shridhar P. Gejji, Debamitra Chakrovorty, Rajesh Gonnade, Tania Moniz, Maria Rangel, Eulalia Periera, Sunita Salunke-Gawali
Year
2017
Journal
Journal of Molecular Structure
Abstract
The vitamin K3 derivatives 2-methyl-3-[(pyridin-2-ylmethyl)-amino]-1,4-naphthoquinone (M-1), 2-methyl-3-[(pyridin-2-ylethyl)-amino]-1,4-naphthoquinone (M-2), 2-methyl-3-((2-(thiophen-2-yl)methyl)amino)naphthalene-1,4-dione (M-3) and 2-methyl-3-((2-(thiophen-2-yl)ethyl)amino)naphthalene-1,4-dione (M-4) have been synthesized, characterized and studied for their chemosensor abilities towards transition metal ions. Crystal structures of M-1, M-2 and M-4 revealed a variety of Nsingle bondH⋯O, Csingle bondH⋯O, Csingle bondH⋯π and π⋯π interactions. Minor variations in such interactions by chemical stimuli such as metal ions, results in change in color that can be visualized by naked eyes. It has been shown that electronic structure and 1H NMR, vibrational as well as electronic spectra from the density functional theory agree well with the experiments. The metal ion binding in ethanol, ethanol-water and in mild base triethylamine brings forth recognizing ability M-1 toward Ni2+ with M-2 exhibiting large sensing ability for Cu2+ ion. Interestingly M-1 display varying metal ion binding specificity in different solvents with the association constant in ethanol being 11,786 M−1 for Ni2+ compared to 9462 M−1 for the Cu2+. A reversal in preferential binding of M-2 with the respective association constants being 4190 M−1 and 6370 M−1 is discernible.
Instrument
FP-8300
Keywords
Fluorescence, Ligand binding, Quenching, Materials, Sensors