Ionic bond in hydrogen transferring of the ferrous and/or ferric human/mouse verdoheme oxygenase

Formation of five coordinated ferric (ferrous) verdoheme oxygenase complexes have been investigated at ωB97X-D/6-31G(d) level of theory. This process was carried out by adsorption of imidazole and human/mouse verdoheme oxygenase (VO) compounds. Global reactivity indexes show electrophile and nucleophile roles of the VO complexes and Imidazole, respectively. This result confirms their interaction, molecular electrostatic potential (MEP) maps, and low HOMO_FRVMO-LUMO_Imidazole gap. These interactions can cause in adsorption and five coordinated of the VO complexes. More negative value (-64.3 kJ mol^-1) of adsorption energy (E_ads) in the FRVMO complex shows better adsorption strength and stable configuration. Significant point of this interaction is hydrogen transfer from imidazole to the nearest oxygen of the VO complexes; this issue is approved using quantum theory of atom in molecule (QTAIM) and natural bond orbital (NBO) analysis. QTAIM calculations confirm ionic bonding between the transferred hydrogen and the oxygen atom of the VO. The 312.2-kcal mol^-1 s order stabilization energies in this complex are confirmation for strong donation and better formation of five coordinated complex in electron view point.

Theoretical kinetics and thermodynamics study: Peripheral substituent effects on the hydrolysis of verdoheme

The heme oxygenase (HO) enzyme is a free heme protein that binds to heme in the body. Heme acts as both a cofactor and a substrate in this enzyme. The catabolism of heme into biliverdin, monoxide carbon, and free-iron, catalyzed by heme oxygenase via three consecutive oxygenation steps, in which the heme group functions as the prosthetic group as well as the substrate. Investigations of the reactions of the peripheral substituent on the heme ring with 5-oxaporphyrin iron complexes (verdohemes) have been assumed to provide models and largely unknown for the primary step in the hydrolysis of verdohemes. In this work, a theoretical kinetics and thermodynamics study of the degradation reactions of verdohemes was performed, and calculations show that the [Formula: see text] in the hydrolysis of verdohemes with non-peripheral substituents is more negative than hydrolysis of verdohemes with peripheral substituents. In other words, the hydrolysis of verdohemes with non-peripheral substituents is more energy-efficient than verdohemes with a peripheral substituents. Equilibrium constant calculations show that hydrolysis of verdohemes with non-peripheral substituents is much faster than that of verdohemes with peripheral substituents, which is due to a more convenient nucleophilic attack on the cationic ring than the anionic ring. To acquire a good molecular understanding, peripheral substituent effects on the hydrolysis of verdoheme’s inhibitory role was studied using the DFT method.

Screening metal-dicorrole-based dyes with excellent photoelectronic properties for dye-sensitized solar cells by density functional calculations

The dye molecules behaving as photosensitizers in dye-sensitized solar cells are the most critical factors to determine the power conversion efficiency. Therefore, ways to design dye molecules with excellent photoelectric properties has been the focus of dye-sensitized solar cells research. Here, we selected four representative different metal-corrole monomers to characterize their structures and photoelectronic properties. Then based on these metal-corrole monomers, six different architectures of metal-dicorroles were designed by varying the linking forms. The most stable architecture [Formula: see text] was screened out by binding energy calculations. A further two types of metal-dicorrole-based dyes were constructed by incorporating different bridge groups with the cyanoacry acceptor into the stable metal-dicorroles. A large number of density functional theory calculations and photoelectric properties analysis indicate that among these different metal-dicorrole-based dyes, Ga-dicorrole dyes have two strong and wide absorption bands in the visible region corresponding to Soret and Q bands, respectively, and have high charge separation efficiency under optical excitation. Especially for Ga-SN dye, by incorporating a [Formula: see text]-bridge-conjugated group, its Soret absorption band is greatly enhanced, broadened and red-shifted, resulting in its merging with the Q band into one absorption band. Moreover, its charge transfer efficiency is up to 76.86%, which will facilitate its coupling with semiconductor materials and transfer its electrons to the semiconductor materials.