Chalcones isothiocyanate anchored into mesoporous silicate: Synthesis, characterization and metal ions sensing response

Abstract

Fluorescent nanosensors are one of the most efficient techniques used for detection of toxic metal ions, based on ligand embedded into mesoporous materials. Here, novel ligands of chalcone isothiocyanate analogue namely; phenyl chalcone isothiocyanate (PCITC), naphthyl chalcone isothiocyanate (NCITC) and anthryl chalcone isothiocyanate (ACITC) were synthesized. Also, the 3D mesoporous silicate, KIT-6, was prepared through surfactant-template method. The design of fluorescent nanosensors was achieved by anchoring of CITCs into KIT-6 via the coupling agent (3-aminopropyl) triethoxysilane (APS). The obtained mesoporous silicate and CITCs anchored forms were characterized using different spectroscopic techniques. Among of metal ions, the most widely toxins, Pb(II), Cu(II) and Pd(II) were studied. Sensing of these metal ions was performed using steady-state absorption and emission techniques. A gradual increase in the absorption spectra was observed upon increasing the concentrations of the used metal ions ranging from 5ppb to 1ppm, with instantaneous color change. Also, a great enhancement in the fluorescence intensity was clearly observed, confirming the formation of [M(CITCs-KIT-6)n]2+ complexes. The calculated binding constants show the high efficiency of PCITC-KIT-6 nanosensor in binding and detection of these metal ions. Moreover, Pb(II) is the strongest binded metal ion with the investigated fluorescent nanosensors. Therefore, CITCs fluorescent nanosensors are suitable for the on-line analysis and remote determination of these toxic metal ions, specially Pb(II), at low concentration levels.