Substituent effect on the structure and properties of dialumene

In this work, we report a theoretical study on molecular structure, and electronic properties of dialumene (ArAl = AlAr, Ar = aryl) and substituted dialumene. The effects of the substituent groups on the structure, electronic properties, ionization potential (IP), electron affinity (EA), and reorganization energy were studied. Theoretical calculations were carried out by density functional theory (DFT) using the B3LYP hybrid function combined with the 6-311 + G(d) basis set. The most intensity electronic transition energy and oscillator strength of molecules were calculated by time-dependent density functional theory (TD-DFT) and shows λ_max blue-shifted in withdrawing electron substituents. Quantum theory of atom in molecules was used for explain of AlAl and AlC bonds in all molecules.     

Substituent and solvent effects on geometric and electronic structure of C<Subscript>5</Subscript>H<Subscript>5</Subscript>Ir(PH<Subscript>3</Subscript>)<Subscript>3</Subscript> iridabenzene: A theoretical insight

Using MPW1PW91 quantum chemical calculations, we report structures, frontier orbital analysis, natural bond analysis, and aromaticity of the C₅H₅Ir(PH₃)₃ iridabenzene and XC₅H₄Ir(PH₃)₃ para-substituted iridabenzenes. The substituent effects were estimated from the donor–acceptor interaction energies of the natural bond orbitals of substituent and iridabenzene frame. Nucleus-independent chemical shift (NICS) has been evaluated to understand the aromaticity. Time dependent density functional theory (TD-DFT) is used to calculate the energy, oscillatory strength and wavelength absorption maxima (λ_max) of electronic transitions and their nature. Changes in hyperpolarizability of molecules are studied. Influence of solvent on the structure, frontier orbital energies, λ_max, and hyperpolarizability of C₅H₅Ir(PH₃)₃ iridabenzene has been studied.     

Theoretical approach to the molecular structure,chemical reactivity,molecular orbital analysis,spectroscopic properties (IR,UV, NMR), and NBO analysis of deferiprone

In this investigation, the structural, electronic properties, ¹³C and ¹H NMR parameters and the first hyperpolarizability of deferiprone are computed in the gas phase and various solvents at the M062X/6-311++G(d,p) level of theory. The solvent effect on the structural parameters, frontier orbital energies, ¹³C and ¹H NMR parameters is also explored based on a polarizable continuum model. These consequences specify that the polarity of solvents affects the structures and spectroscopic properties of deferiprone. ¹H and ¹³C NMR chemical shifts are evaluated by employing the gauge-invariant atomic orbital method. NBO analysis is exploited to examine the hybridization of atoms, atomic charges, and their second order stabilization energy within the molecule.     

Sensitization of the analytical methods for photoneutron calculations to the wall concrete composition in radiation therapy

The effect of wall material on photoneutron production in radiation therapy rooms was studied using Monte Carlo (MC) simulations. An analytical formula was proposed to take into account the concrete composition in photoneutron dose calculations. Using the MCNPX MC code, the 18 MV photon beam of the Varian Clinac 2100 and a typical treatment room with concrete compositions according to report No. 144 of National Council of Radiation Protection (NCRP) were simulated. Number of room produced photoneutrons per Gray of X-ray at the isocenter was determined for different types of concrete and named as “Q_W”. This new factor was inserted in the used formula for photoneutron fluence calculations at the inner entrance of maze. The photoneutron fluence was calculated using new proposed formula at the inner entrance of maze for all studied concretes. The difference between conventional and proposed equations varied from 11% to 46% for studied concretes. It was found that room produced photoneutrons could be significant for high density concretes. Additionally, applying the new proposed formula can consider the effect of wall material composition on the photoneutron production in high energy radiation therapy rooms. Further studies to confirm the accuracy of newly developed method is recommended.     

Theoretical insights into the properties of the XY≡YX...M<Superscript><Emphasis Type="Italic">n</Emphasis>+</Superscript> complexes (X = H,F, Cl; Y = C,Si; M = alkaline and alkaline earth metals)

The character of alkaline (M⁺= Li, Na, K) and alkaline earth metal ions (M²⁺= Be, Mg, Ca) interactions with disilyne and acetylene has been studied by using high-level ab initio computations. The interaction energies were calculated at MP2/6-311++G(2d,2p) level. These calculations show that the size and charge of cation are two significant factors that affect the character of interaction. AIM and NBO analyses of M ⁿ⁺...X₂Y₂ interactions specify that the variation of densities and the extent of charge transfers upon complexation correlate well with the obtained interaction energies.     

Theoretical Analysis of Solvent Polarity Effect on the Electronic and Spectroscopic Properties (IR and UV) of the Ni(CO)2(NHC)2 Complex (NHC = 1H-Imidazol-2-ylidene)

Russian Journal of Physical Chemistry A - In this study, using the wB97XD functional, quantum chemical calculations were used to analyze the solvent effect on the structural, electronic and...     

Insight into the solvent effect on the structure,IR-spectrum,and hyperpolarizability of CpMe<Subscript>2</Subscript>Ta(benzyne), a mononuclear Tantalum–benzyne complex

In this investigation, quantum chemical calculations using MPW1PW91 method were applied to analyze of the solvent effect on the structural, vibrational analysis, thermochemical parameters and first hyperpolarizability for CpMe₂Ta(benzyne) complex. The solvent effects on the structure and properties were examined by the self-consistent reaction field theory (SCRF) based on Polarizable Continuum Model (PCM). Good correlations exist between these parameters and dielectric constants of solvents. The wavenumbers of the IR-active symmetric stretching vibrations of Ta-Me in different solvents were correlated with the Kirkwood–Bauer–Magat equation (KBM). In addition, Monte Carlo simulations using standard procedure of Metropolis sampling were applied to investigate of the solvation of CpMe₂Ta(benzyne) complex. In addition, the bonding interaction between the CpTaMe₂ and benzyne fragments was analyzed by means of the energy decomposition analysis (EDA).     

HYDROGEN ADSORPTION AND STORAGE ON PALLADIUM-FUNCTIONALIZED C20 BOWL AND C20H10 BOWL MOLECULE INCLUDING HYDROGEN SATURATION

Journal of Structural Chemistry - This study investigated hydrogen molecule adsorbing on palladium-functionalized C20 bowl and its H-saturated form (C20H10 bowl) using the B3LYP-D3 model. Moreover,...     

Borazine-based conjugated derivatives: Structural,electronic, and optical properties

The structural characteristics, electronic properties, and nonlinear optical properties of borazine-based conjugated derivatives have been explored at B3LYP/6-311G(d,p) level. The effects of various electron donor and acceptor substituents (H, F, Cl, Br, Me, CF₃, NH₂, OH, COOH, CHO, NO₂) on the structure, polarizability, frontier orbitals, the most intense electronic transition, and hyperpolarizabilities have studied. Calculations show that NO₂-substituted molecules have lowest hardness, the largest isotropic polarizability and anisotropy of polarizability, and first hyperpolarizability.