ZnAl₂O₄ Nanomaterial as a Naked-Eye Arsenate Sensor: A Combined Experimental and Computational Mechanistic Approach

Abstract

Raising public awareness over the emerging health risk due to intake of arsenic-contaminated potable water is a matter of great concern. Exploration of cost-effective, self-testing kits is a substantial way to reach out to the masses and detect the presence of arsenate in water. With this agenda, a photoluminescent Mannich base Zn­(II) complex (ZnMC = [Zn2(ML)2]·(ClO4)2·(H2O); HML = Mannich base ligand) has been synthesized, and its dinuclearity was verified with single-crystal X-ray diffraction structural analysis. Among a range of anions, ZnMC was found to detect arsenate selectively by showing a turn-off emission with a color change from bright green to dark under UV light. The real-life applicability of the ZnMC probe is somewhat restricted to only sensing of arsenate, but not its removal owing to the fact of its homogeneity. Considering the efficacy of ZnMC as well as a need for its easy removal from water, slight modification has been done with chloride ions in the form of ZnMC″ (=[Zn2(ML)2(Cl)2]), and finally, an interface between homogeneous and heterogeneous solid support has been explored with a strategic fabrication of ZnMC″ grafted ZnAl2O4, named as ZAZ nanomaterial. This not only imparts successful segregation of arsenate from drinking water but also provides naked-eye detection under ambient light as well as UV light. Thermodynamic parameters associated with the binding of arsenate to ZnMC and ZAZ have been evaluated through isothermal calorimetric (ITC) measurements. Steady-state and time-resolved fluorescence titration study, absorption titration study, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and computational calculations have been performed to get deep insights into the sensing properties. Proper justification of the sensing mechanism is the highlight of this work. ZAZ nanomaterial has been exploited to produce a self-test paper kit for arsenate detection with a limit of 9.86 ppb, which potentially enables applications in environmental monitoring.

Ni(II)-Complex Anchored onto Magnetically Separable Oxidized Single-Walled Carbon Nanohorn: A DFT-Supported Mechanistic Approach for Hydrogen-Borrowing Quinoxaline Synthesis

“…Density functional calculations have successfully enlightened the thermodynamic feasibility of various metal complex-based chemical transformations, with the help of the critical structures associated with the reaction procedures. – …”

Porous and Ag-, Cu-, Zn-Doped Al2O3 Fabricated via Barrier Anodizing of Pure Al and Alloys

“…In each case, doped "boundary" layers can find applications. In case the exact formation of CuAlO 2 , AgAlO 2 and ZnAl 2 O 4 compounds is proved, the electrochemical synthesis of their thin layers for other promising applications actively under consideration, such as transparent conductive films [115][116][117][118][119][120][121][122][123], may be of interest for photoelectronic [124] and mechanical applications [125], optoelectronics [125], photo-thermoelectric and thermoelectric applications [126,127], fluorescence materials [128], sensors [125,[129][130][131], and electro-and photocatalysts [132][133][134][135][136].…”

A strategy for modulating the catalytic active center of AP thermal decomposition and its application: La-doped MgCo2O4

“…36 Moreover, there is no La-O bond vibration peak in the FT-IR spectrum, which is consistent with the XRD data, further conrming the successful diffusion of La 3+ . The absorption bands at 861 cm −1 and 1386 cm −1 correspond to the C-O and C-H stretching vibrations, respectively, 37,38 which may come from some carbon remaining during the solution combustion synthesis. The FT-IR spectra of the samples have similar absorption bands at 1637 cm −1 and 3434 cm −1 , which are related to the O-H stretching and bending vibrations of the adsorbed water molecules, respectively.…”