Synthesis and evaluation of phosphonato-triphenylamine fluorophore as a highly sensitive chemosensor for nitroaromatics

Abstract

A sodium (nitrilotris(benzene-4,1-diyl))tris(phosphonic acid) (TPAP) molecular architecture has been synthesized and characterized by modern spectroscopic techniques. The photophysical behaviour of TPAP has been examined using UV-Vis absorption, fluorescence spectra, and time-resolved emission techniques. TPAP showed absorption maxima at 312 nm and strong emission peak at 392 nm with quantum yield 23.55 percent. Further, TPAP is employed for the nitroaromatics (NACs) detection in H sub(2)O media. TPAP exhibited more pronounced sensitivity towards trinitrophenol, i.e., picric acid (PA) over nitrophenol (NP) and dinitrophenol (DNP). The sensor TPAP shows turn-off fluorescence behavior upon interaction with PA with a lower limit of detection to be 5.35x10 sup(-8) M. Theoretical studies such as DFT calculations were employed to establish the sensing mechanism of TPAP. The molecular recognition of TPAP with PA is attributed to cooperative H-bonding, resulting in superior detection of PA. Thus, the developed TPAP sensor provides an appropriate method for PA detection and could be explored for environmental samples.