International Journal of Quantum Chemistry最新文献

Chemical graph theory is an important field in mathematical chemistry that uses domination degree-based indices to convert the chemical structure of molecules into numerical values. These indices help investigate physico-chemical properties, pharmacokinetic properties, and biological activity in QSPR and QSAR studies. Among the most life-threatening diseases, cancer remains a major global health concern. Various anticancer drugs like Tegafur, Floxuridine, etc., are employed to combat different cancer types. This paper designs a QSPR model to predict selected physico-chemical and ADMET properties of these anticancer drugs using indices like the first, second, and modified first Zagreb domination topological index; forgotten, hyper, and modified forgotten domination topological index; and first, second, and modified first Zagreb $��\gamma �$-domination topological index; forgotten, hyper, and modified forgotten $��\gamma �$-domination topological index, via $��{�\varphi �}_{�d�}�$- and $��{�\varphi �}_{�\gamma �}�$-polynomials. The relationship analyzes for these properties with the domination degree-based indices are conducted using the inverse cubic regression method. The results can correlate with other properties, aiding in constructing a disease-based drug library.

Oligothiophenes have attracted a lot of attention due to their excellent photoelectric properties. However, the effects of ring fusion and furan substitution on the optoelectrical properties of oligothiophenes are still unclear. In this study, based on popular pentathiophene, eight molecules including three ring-fused and five furan-substituted derivatives are systematically designed, and their frontier molecular orbitals, dipole moments, planarity, exciton binding energy (E_b), singlet-triplet energy differences, and fluorescence quantum yields are calculated. The computed data demonstrate that full-ring fusion and two- and more-furan substitutions can greatly enhance the fluorescence quantum yields. Five potential molecules with about 100% of fluorescence quantum yield, i.e., TTTTT, SOSOS, OSOSO, SOOOS, and OOOOO, are screened. The results show that to obtain high fluorescence quantum yield, high E_b is required, and the flexible torsional displacement during the excitation from ground to the first excited state should be removed as much as possible. This work sheds some light on the future design of high-performance oligothiophene-based fluorescent materials.

The global potential energy surface (PES) of PH₂⁺(1³A″) was constructed using permutation invariant polynomial neural network method based on 18 566 ab initio energy points. In ab initio calculation, aug-cc-pVQZ and aug-cc-pwCVQZ basis sets were used for H and P⁺, respectively. The topographic features of the PES were discussed in detail and compared with available theoretical and experimental values. The results indicate that the PES is well fitted by using neural network method. In addition, quasi-classical trajectory (QCT) calculations were carried out for the P⁺(³P) + D₂ reaction in the collision energy range from 1.2 to 8.0 eV. The integral cross sections were reported and compared with experimental data. The differential cross sections were also calculated, and it reflects that the “complex-forming” mechanism dominates the reaction in the low collision energy range, and direct abstraction mechanism plays a dominant role in the high collision energy range.

In this paper, we have explored the influence of alkylene-bridged length and coordination mode on the reactivity of a series of 24 alkylene-bridged palladium complexes using computational tools (B3PW91/LANL2DZ//6-31G(d) level) in gas phase and DMSO. These palladium complexes prefer a boat and chair configuration for methylene and ethylene bridge length, respectively. In addition, phenyl and nitro complexes present a higher activation for Pd—C bonds while the most stable Pd⋯C interactions are observed for abnormal mode with methylene bridge. According to the energy decomposition analysis (EDA), hydrogen and phenyl complexes in both chelation modes present a better electrostatic character. Moreover, Pd⋯C interactions are stronger compared to the Pd⋯X ones for ethylene-bridged abnormal complexes (in gas phase). Finally, the donation/back-donation ratio (d/b) values reveal the Fischer carbene character of these [bis(NHC)]⋯[PdX₂] interactions. Concerning the hybridization around the metal cation for the Pd—C bond, the sp²d type is observed for methylene-bridged palladium complexes while the sp³ one is observed for ethylene bridge complexes.

Topological indices (TIs) are numerical parameters that characterize the biochemical and physio-chemical properties of compounds. These graph-based descriptors are valuable tools for predicting key attributes, such as melting points, boiling points, bond energies, and bond lengths, based on the molecular structures of the compounds. A variety of TIs have been developed, including the Randić index, Zagreb index, atom-bond connectivity index, geometric index, and harmonic index. In this work, we introduce a new topological index called the neighborhood face index, which demonstrates a strong correlation with various physical properties such as bond energies and boiling points, achieving a correlation coefficient of $��R�\ge �0.9994�$. This indicates its robust predictive capability. Furthermore, the results are thoroughly analyzed using graphical tools to provide deeper insights.

Alzheimer's disease (AD) is a neurodegenerative condition that leads to the deterioration of brain cells, resulting in memory loss, thinking, and executive skills. In this work, 4-amino-2-chloro-6,7-dimethoxyquinazoline (ACDQ) has been studied using the 6–311++G(d,p) B3LYP functional of the density functional theory (DFT) approach utilizing a basis set. Geometry optimization and fundamental vibrational frequencies are calculated using the above method. The spectroscopic investigations such as FT-IR, FT-Raman, and UV–Vis spectra are performed on the selected compound. The time-dependent DFT calculations are performed in the gas and water phases to determine electronic properties and energy gap using the same basis set. Charge density distributions have been used to illustrate the energy gap between the highest occupied and lowest unoccupied molecular orbitals. Mulliken population analysis is performed to determine the atomic charges of ACDQ. From the natural bond orbital analysis, it is observed that there is a significant electron delocalization in ACDQ due to the presence of intramolecular interactions. To evaluate ACDQ's anti-Alzheimer potential, a molecular docking simulation is used to assess its structural stability and biological activity against proteins associated with Alzheimer's disease. Our docking study revealed that, ACDQ has a strong interaction with 4EY7 protein with binding energy of −8.1 kcal mol⁻¹. Additionally, metrics such as the root mean square deviation (RMSD), root mean square fluctuation (RMSF), and the radius of gyration are considered (R_g) were computed using molecular dynamics simulations to evaluate the stability of the protein–ligand interaction. Studies on the ADMET prediction of ACDQ have also been carried out. The findings of the current study support the potential of ACDQ as an effective lead therapeutic for Alzheimer's disease.

A novel planar monolayer graphene metamaterial structure containing rectangular interrupted graphene is proposed. Dynamically tunable multiple plasmon-induced transparency (PIT) and slow light are obtained within the terahertz band through destructive interference between continuous dark and interrupted bright modes. Two distinct graphene types function as the optical dark and bright modes, and continuous graphene array is the nonradiative dark mode, whereas interrupted graphene array is the broad linewidth bright mode, respectively. Given the existence of graphene structure in the continuous state, continuous graphene Fermi level is dynamic tuned through the simple use of the bias voltage. Expressions of n-order coupled mode theory (CMT) are correctly deduced, with CMT fitting theoretical analysis being identical to finite-difference time-domain numerical simulation based on dual- and triple-PIT results for n = 3 and n = 4 cases, respectively. The continuous graphene Fermi level increases within 0.7–1.1 eV; the group index of the dual-PIT system is maintained within 475.1–801.6, while that of the triple-PIT system is 583.3–886.3. Additionally, the maximal group index is as high as 886.3 at 1.1 eV, indicating that an outstanding slow light device is established. Consequently, these proposed structures and research outcomes can guide the design of multichannel optical filters, excellent slow light devices, and dynamically tunable optical modulators.

The relativistic Thomas–Fermi model is revisited in the framework of von Weizsacker's kinetic energy functional. This model, already studied by other authors, is optimized by weighting the von Weizsacker functional with a numerical parameter and introducing a retardation term in the potential energy functional to improve its predictivity when applied to systems with a complex electronic structure. These corrections avoid overestimating the total kinetic energy and underestimating the stabilizing effect of the Coulomb potential, respectively. The model is applied to neutral and ionized atoms with increasing atomic numbers to test the qualitative and quantitative predictivity goodness of the relativistic effects. Due to the simplicity of solving the relativistic equation by numerical methods, the proposed model could be an alternative or a supportive tool to other computational methods for studying the physicochemical properties of compounds containing heavy atoms.

This study delves into the electronic, magnetic, and optical properties of Tm-doped wurtzite Al_xGa_1−xN alloys, utilizing first-principles density functional theory (DFT) calculations. By applying the LSDA+U approach to capture the strong correlation effects of 4f-Tm electrons, our findings reveal that Tm-doped Al_xGa_1−xN exhibits semiconducting behavior with inherent ferromagnetic order. Remarkably, the bandgap of Tm-doped Al_xGa_1−xN transitions from indirect to direct at an Al content (x) of 0.25, highlighting its potential for dual electrical and magnetic functionalities. The magnetic moments are highly localized at Tm sites, suggesting the feasibility of Tm as a dopant for developing AlGaN-based diluted magnetic semiconductors. Moreover, the observed spin-dependent characteristics and magnetic interactions in Tm-doped Al_xGa_1−xN underscore its applicability in spintronic devices, including spin transistors and spin logic circuits, which could significantly advance next-generation electronic systems. Additionally, the study predicts a blue shift in luminescence for Tm-doped Al_xGa_1−xN, which is attributed to the interplay between Tm dopant energy levels, Al composition, and the host alloy's band structure, as well as energy transfer and quantum confinement effects. This positions Tm-doped Al_xGa_1−xN as a promising material for applications in solid-state lighting, displays, lasers, and other optoelectronic devices requiring blue light emission.