Stability, spectroscopic, electrochemistry and QTAIM analysis of Cu-Znn-1On clusters for glucose sensing application: A study on theoretical and experimental insights.

Clusters of (ZnO)n (n = 2-4) have been shown to play a central role in the detection of glucose entity based on the existence of photo-induced electrons (PE), which facilitates the interaction between (ZnO)n clusters and glucose entity guests. The electrochemistry experiment has confirmed the detection of glucose by the title clusters. The optimization, energetic parameters, and vibrational frequency calculations have indicated that the Cu-Znn-1On-glucose are more stable than the (ZnO)n-glucose complexes. It has been demonstrated that the Cu doping enhanced the chemical behavior of the clusters and formed a high intramolecular charge transfer (ICT) in the system. The glucose sensing by all the forms of Cu-Znn-1On clusters showed that the Cu-Zn3O4, Cu-Wurtzite, and Cu-Rocksalt clusters are the most suitable for adsorbing the glucose guest. The HOMO/LUMO iso-surfaces of the complexes showed that the electron concentrations are localized in the d orbitals and mainly in the form of the d10 orbitals around Zn atoms. The molecular electrostatic potential (MEP) has clearly indicated that a high charge transfer occurs between the copper and the oxygen atoms, which facilitate the adsorption of glucose. The reactivity parameters also indicated that the Wurtzite-glucose complex has a high electrophilicity index (ω), which means a good acceptor behavior to interact with glucose. Additionally, the bond between the (ZnO)n clusters and the glucose polar element has been studied in detail by using QTAIM theory. Finally, the theoretical and experimental studies prove that the Cu-Znn-1On clusters are very suitable and competent compounds for detecting glucose.

Azo-methoxy-calix[4]arene complexes with metal cations for chemical sensor applications: Characterization, QTAIM analyses and dispersion-corrected DFT- computations.

In this work, the structures, quantum chemical descriptors, morphologic characterization of the azo-methoxy-calix[4]arene were investigated. The analyses and interpretation of the theoretical and the experimental IR spectroscopy results for the corresponding compounds was performed. The complexation of the azo-methoxy-calix[4]arene with Zn2+,Hg2+ , Cu2+ , Co2+, Ni2+ , Pb2+ and Cd2+metal cations has been calculated by the dispersion corrected density functional theory (DFT-D3). The values of the interaction energies show that the specific molecule is more selective to the Cu2+ cation. The study of the reactivity parameters confirms that the azo-methoxy-calix[4]arene molecule is more reactive and sensitive to the Cu2+ cation than that Co2+ and Cd2+. In addition, the investigation of the electrophilic and nucleophilic sites has been studied by the molecular electrostatic potential (MEP) analysis. The Hirshfeld surface (HS) analysis of the azo-methoxy-calix[4]arene-Cu2+ interaction have been used to understand the Cu⋯hydrogen-bond donors formed between the cation and the specific compound. The Quantum Theory of Atoms in Molecules (QTAIM) via Non covalent Interaction (NCI) analysis was carried out to demonstrate the nature, the type and the strength of the interaction formed between the Cu2+ cation and the two symmetrical ligands and the cavity. Finally, the chemical sensor properties based on the Si/SiO2/Si3N4/Azo-methoxy-calix[4]arene for detection of Cu2+ cation were studied. Sensing performances are determined with a linear range from 10-5.2 to 10-2.2 M. The Si/SiO2/Si3N4/azo-methoxy-calix[4]arene structure is a promoter to have a good performance sensor.