Sensitive turn-off detection of nitroaromatics using fluorescent tetraphenylethylene phosphonate derivative

Abstract

The derivatisation of tetraphenylethylene is broadly utilized to synthesize molecular sensor for detecting explosives among other analytes, the effects of such alteration have been little investigated. Herein, we report the sensing of various nitro phenols using fluorescence signals produced by (4-(1, 2, 2-tris (4-phosphonophenyl) vinyl) phenyl) phosphonic acid octasodium salt (TPPE). It is observed that the fluorescence of TPPE at 411 nm and 432 nm are quenched in the presence 2,4,6-trinitrophenol (TNP) via electron transfer between weak TPE donor and acceptor mechanism. Moreover, TPPE - TNP association is based on non-covalent interaction including hydrogen-bonding and electrostatic interactions. TPPE shows strong binding affinity and selectivity towards TNP over various other nitroaromatic analytes. The sensing detection limit (LOD) towards TNP is 4.58 x 10-9 M. In detailed molecular simulation experiments are performed to investigate the non-covalent interaction, oscillation frequency, possible transitions and energy levels of molecular complexation between TPPE and TNP. This study supports the sensing mechanism of TPPE towards TNP, suggesting suitable interaction mode between the receptor and PA.