Solvent and substitution effects on the structure and properties of a half-sandwich complex of vanadium with a terminal borylene ligand: Theoretical study

The structures and properties of a terminal borylene vanadium complexes CpV(CO)₃(BNH₂) were explored using theoretical methods. The density of states (DOS) was beneficially used to analyze the main features of electronic structure. The influence of solvent on the structural parameters, frontier orbital energies and wavelength absorption maxima (λ_max) of this structure was studied. These calculations were performed in different solvents, i.e. cyclohexane, dichloromethane, tetrahydrofuran, chlorobenzene, and chloroform, utilizing the self-consistent reaction field (SCRF) theory. Also, substituent effect in CpV(CO)₃(BNR₂) complexes on the structure and properties was investigated.     

Magnetic Nanoparticles Supported Ionic Liquids Improve Firefly Luciferase Properties

Ionic liquids as neoteric solvents, microwave irradiation, and alternative energy source are becoming as a solvent for many enzymatic reactions. We recently showed that the incubation of firefly luciferase from Photinus pyralis with various ionic liquids increased the activity and stability of luciferase. Magnetic nanoparticles supported ionic liquids have been obtained by covalent bonding of ionic liquids-silane on magnetic silica nanoparticles. In the present study, the effects of [γ-Fe₂O₃@SiO₂][BMImCl] and [γ-Fe₂O₃@SiO₂][BMImI] were investigated on the structural properties and function of luciferase using circular dichroism, fluorescence spectroscopy, and bioluminescence assay. Enzyme activity and structural stability increased in the presence of magnetic nanoparticles supported ionic liquids. Furthermore, the effect of ingredients which were used was not considerable on K _m value of luciferase for adenosine-5′-triphosphate and also K _m value for luciferin.     

A quantum chemistry study of ruthenabenzene complexes

The electronic structure and properties of the ruthenabenzenes and substituted ruthenabenzenes have been explored using the hybrid density functional B3LYP theory. Systematic studies on the substituent effect in para-substituted ruthenabenzenes complexes have been studied. The following substituents were taken into consideration: H, NO₂, CN, CHO, COOH, F, CH₃, OH, and NH₂. Basic measures of aromatic character were derived from the structure and nucleus-independent chemical shift (NICS). The NICS calculations indicate a correlation between NICS(1.5) and the hardness in all species. The atoms in molecule analysis indicates a correlation between r(Ru-C) bonds and the electron density of bond critical point in all species.     

A theoretical study of the solvent effect on the interaction of C<Subscript>20</Subscript> and N<Subscript>2</Subscript>H<Subscript>2</Subscript>

In this work, the interaction of C₂₀ and the N₂H₂ fragment is investigated at the M062X/6-311G(d,p) level of theory in both gas and solution phases. The interaction energies obtained by the standard method are corrected by the basis set superposition error (BSSE) during the geometry optimization for all molecules at the same levels of theory. The results obtained from these calculations reveal that the interaction between C₂₀ and N₂H₂ increases in the presence of more polar solvents. Values of the electrophilic charge transfer show the charge flow from C₂₀ to N₂H₂. The influence of the solvent on the hyperpolarizability indicates that β_tot values decrease on passing from vacuum to the solution phase.     

Quantum Mechanical Study of Substituent Dependence on the Structure,Spectroscopic (13C, 1H NMR and UV), NBO,Hyperpolarizability and HOMO?LUMO Analysis of Ru(NHC)2Cl2(CH‐p‐C6H4X) Complexes

In this work, we have explored the structural, electronic properties, ¹³C and ¹H NMR parameters and first hyperpolarizability of Ru(NHC)₂Cl₂(CH‐p‐C₆H₄X) complexes (XH, F, Cl, Me, NH₂, OH, CN, NO₂, CHO, COOH) by mpw1pw91 quantum method. The X‐substituent effect on structural parameters, frontier orbital energies, spectroscopic (¹H and ¹³C NMR, UV) of complex was carried out. The results indicate that the substituent has played a significant role on the structures and properties of complex. ¹H and ¹³C NMR chemical shifts were calculated by using the gauge‐invariant atomic orbital (GIAO) method. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were exhibited. In analyzing the bonding characteristics of this structure, Ru‐C_carbene and Ru‐C_NHC bonds were identified and characterized in details by Natural bond orbital (NBO) analysis.     

Theoretical study of solvent and substituent effects on the structure, <Superscript>14</Superscript>N NQR and electronic spectra of [Cr(CO)<Subscript>5</Subscript>py]

The structure, ¹⁴N NQR parameters, electronic spectra, and hyperplarizability of [Cr(CO)₅py] in seven different solvents were theoretically computed with MPW1PW91 method based on Polarizable Continuum Model (PCM). The substituent effects in para- substituted Cr(CO)⁵–pyridine complexes have been evaluated. The results indicate that both polarity of solvents and the substituents have played a significant role on the structures and properties of complexes. The study also shows that the structural and solvent modification change the NLO properties.     

Theoretical study on platinabenzene and mono- and difluorinated platinabenzenes: Structure, properties, and aromaticity

The electronic structures and properties of the platinabenzene and mono- and difluorinated platinabenzenes isomers have been investigated using hybrid density functional B3LYP theory. Basic measures of aromatic character were derived from structure, molecular orbital, and nuclear independent chemical shift (NICS). An energetic criterion suggests that ortho isomer of monofluorinated and F15 isomer of difluorinated platinabenzenes enjoy conspicuous stabilization. The polarizability and molecular orbital analysis are compatible with this result. NICS values calculated at several points above the ring center fail to give the result consistent with that based on relative energy, polarizability, and molecular orbital analysis. The atoms in molecules analysis indicates a correlation between NICS (1.0) and the electron density of the ring critical point (ρ_rcp) in monofluorinated platinabenzenes. There is a similar correlation in difluorinated platinabenzenes (except for F12 and F24 isomers) between NICS (0.5) and ρ_rcp.