Adsorption of toxic and non-toxic metals with new model of CX[4]: Experimental and computational investigation, Spectroscopic, QTAIM, and Antibacterial activity analyses

Abstract

The presence of toxic metals in the environment is a big problem because it can be harmful to human health. Consequently, it is necessary to control the percentage of metals (for example, magnesium) in human body. In this paper, a very efficient model was proposed to detect the toxic or know the presence of the non-toxic metals at the same time. The selected models are capable of adsorbing cations in all active sites, even if they are present in different positions. The structural stability, adsorption sites and charge transfer have been investigated. The models, where all adsorption sites are filled involving azo-ethoxycarbonylmethoxy-calix[4]arene-X2+,3+ (Pb, Cd, Mg, and Eu), are stable and selective for toxic or non-toxic cations. The Hirshfeld surfaces (HS) have been computed at the active sites, where Mg2+, Pb2+ and Cd2+ cations are adsorbed. Theoretical and experimental investigations of the luminescence properties have demonstrated that when adding the three cations in the acceptor sites a very high charge transfer is observed, indicating that the compound is well selective for the three cations. According to the QTAIM theory, a toxic or non-toxic metal may be fixed through strong hydrogen bonding interactions between the guest and its neighboring oxygen atoms. The molecular docking simulation showed that the most stable system azo-ethoxycarbonylmethoxy-CX[4]-Eu3+ exhibits a potential anti-bacterial activity.