Chalcone isothiocyanate-mesoporous silicates: Selective anchoring and toxic metal ions detection

Nanosensors are one of the important applications of mesoporous materials used for toxic metal ions detection. Here, a rational strategy aimed at designing 2D and 3D nanosensors using SBA-15 and KIT-6 types of mesoporous silicates as probe carriers. A novel ligand of chalcone analogue namely, chalcone isothiocyanate, CITC has been synthesized. Covalent anchoring of CITC into mesoporous silicates was performed through two methods: (i) loading via the coupling agent (3-aminopropyl) trimethoxysilane (APS) into calcinated mesoporous silicates, (ii) alkaline loading into amino-functionalized mesoporous silicates. The obtained mesoporous silicates and their CITC anchored forms were characterized using different spectroscopic techniques. The results indicated the higher efficiency of KIT-6 and APS loading method than both SBA-15 and alkaline loading method. Therefore, a highly sensitive nanosensor used for toxic metal ions detection was successfully designed by the anchoring of CITC into KIT-6 via the more efficient APS method. Among of metal ions, the most widely toxins, Cd(II), Co(II) and Sb(III) were studied. The optical sensing of these metal ions was performed using electronic absorption and emission techniques. The absorption spectra increase gradually upon increasing the concentrations of the used metal ions, with significant color changes. Also, a great enhancement in the fluorescence intensity was observed upon adding these metal ions. The spectral changes can be rationalized in terms of the formation of [M(CITCs-KIT-6)n]2+ complexes. These results suggested that CITC/KIT-6 nanosensor is suitable for the on-line analysis and in situ detection of these toxic ions in potable and environmental water samples.

Graphical abstractThe molecular structure of the investigated CITC/mesoporous silicate optical nanosensor.Figure optionsDownload full-size imageDownload as PowerPoint slide