Theoretical and experimental studies on mechanochromic triphenylamine based fluorescent “ON-OFF-ON” sensor for sequential detection of Fe3+ and deferasirox
Abdullah Yahya Abdullah Alzahrani, Khanzadi Omama Khan, Sanwa Rafique, Hasher Irshad, no-firstname Khadija, Asad Muhammad Khan, Sohail Anjum Shahzad
Abstract
A novel triphenylamine (TPA) based sensor TTU was rationally designed and synthesized that exhibited reversible mechanochromic and aggregation induced emission enhancement (AIEE) properties. The AIEE active sensor was employed for fluorometric detection of Fe 3+ in aqueous medium, with distinguished selectivity. The sensor showed a highly selective quenching response towards Fe 3+ that is ascribed to complex formation with paramagnetic Fe 3+ . Subsequently, TTU -Fe 3+ complex acted as a fluorescence sensor for the detection of deferasirox (DFX). The subsequent addition of DFX to TTU -Fe 3+ complex led to the recovery of fluorescence emission intensity of sensor TTU that was attributed to the displacement of Fe 3+ by DFX and release of sensor TTU . The proposed sensing mechanisms for Fe 3+ and DFX was confirmed through 1 H NMR titration experiment and DFT calculations. Frontier molecular orbitals (FMO), density of states (DOS), natural bond orbital (NBO), non-covalent interaction (NCI) and electron density difference (EDD) analysis were performed using DFT calculations to support the experimental results. Moreover, sensor TTU displayed colorimetric detection of Fe 3+ . Further, the sensor was employed for the detection of Fe 3+ and DFX in real water samples. Finally, logic gate was fabricated by using sequential detection strategy.