Theoretical Study on Electronic Structural Properties of Catalytically Reactive Metalloporphyrin Intermediates

Adsorption Behaviors of Chlorosilanes, HCl, and H2 on the Si(100) Surface: A First-Principles Study

The hydrochlorination process is a necessary technological step for the production of polycrystalline silicon using the Siemens method. In this work, the adsorption behaviors of silicon tetrachloride (SiCl₄), silicon dichloride (SiCl₂), dichlorosilane (SiH₂Cl₂), trichlorosilane (SiHCl₃), HCl, and H₂ on the Si(100) surface were investigated by first-principles calculations. The different adsorption sites and adsorption orientations were taken into account. The adsorption energy, charge transfer, and electronic properties of different adsorption systems were systematically analyzed. The results show that all of the molecules undergo dissociative chemisorption at appropriate adsorption sites, and SiHCl₃ has the largest adsorption strength. The analysis of charge transfer indicates that all of the adsorbed molecules behave as electron acceptors. Furthermore, strong interactions can be found between gas molecules and the Si(100) surface as proved by the analysis of electronic properties. In addition, SiCl₂ can be formed by the dissociation of SiCl₄, SiH₂Cl₂, and SiHCl₃. The transformation process from SiCl₄ to SiCl₂ is exothermic without any energy barrier. While SiH₂Cl₂ and SiHCl₃ can be spontaneously dissociated into SiHCl₂, SiHCl₂ should overcome about 110 kJ/mol energy barrier to form SiCl₂. Our works can provide theoretical guidance for hydrochlorination of SiCl₄ in the experimental method.

A Theoretical Study of Metalloporphyrin-Based Fluorescent Array Sensor using Density Functional Theory

The influences of metal atoms on optimized geometry structures, relative energies, frontline molecular orbitals, and binding energies of metalloporphyrin-based fluorescent array sensor were systematically investigated by density functional theory (DFT) at B3LYP/LAN2DZ level. DFT calculated results reveal that the selected metal atoms in the center of the metalloporphyrin plane provide difference performances of metalloporphyrin-based fluorescent array sensor for the rapid determination of trimethylamine. The calculated binding energies have displayed in the following order at the most stable states: zinc porphyrin (ZnP) < copper porphyrin (CuP) < silver porphyrin (AgP) < iron porphyrin (FeP) < tin porphyrin (SnP) < cobalt porphyrin (CoP) < ruthenium porphyrin (RuP) < manganese porphyrin (MnP). Therefore, this theoretical study provides a design mechanism for how to choose a proper metal atom for low or high concentration trimethylamine. This research also suggests that theoretical results may be useful for the rapid detection of food containing trimethylamine.