International Journal of Quantum Chemistry最新文献

The fluorophore 2-butyl-4-hydroxyisoindoline-1,3-dione (BHD) has been obtained experimentally (RSC Adv., 2015, 5, 18177–18182). However, the influence of protic solvent and intermolecular hydrogen bond (InterHB) between BHD and solvent has not been considered. On this foundation, we systematically explored the effect of protic water on the ESIPT mechanism of BHD adopting density functional theory (DFT) and time-dependent DFT (TD-DFT). From a series of data, it can be ensured that the intramolecular hydrogen bonds (IntraHBs) and InterHBs in BHD and its hydrogen-bonded complexes (BHDH₂O, BHD(H₂O)_cyc) are enhanced upon photoexcitation. For BHD, BHDH₂O and BHD(H₂O)_cyc, the proton transfer process can only occur in the excited state. The potential barriers of ESIPT in BHD and BHDH₂O are 2.6362 and 3.8611 kcal/mol, respectively. Clearly, the extra InterHB that does not involve in the proton transfer reaction hinders the ESIPT process in BHDH₂O. For the cyclic hydrogen-bonded complex BHD(H₂O)_cyc, excited state double proton transfer (ESDPT) process occurs in a concerted but asynchronous protolysis pattern, requiring only conquering a potential barrier of 0.0356 kcal/mol, as shown in the potential energy curve. Compared with BHD, the two InterHBs in BHD(H₂O)_cyc obviously reduce the potential barrier and effectively accelerate the ESPT process.

Atomic basis sets play a central role in molecular chemistry and computational studies. While numerous large and specialized basis sets have been developed, the minimal STO-3G basis set continues to be used. It is commonly employed in the testing phase of calculations, for determining magnetic properties of larger systems, and for describing chemical environments in multilayer QM/QM' calculations focused on extended biological or material systems. The original STO-3G basis set was optimized to fit a single atomic Slater-type orbital, with no emphasis on energy or properties. In this study, we explore the possibilities, advantages, and drawbacks of re-optimizing the STO-3G basis set in the following ways: (i) targeting the total energy of different organic molecules rather than atoms during the optimization process; (ii) introducing different basis set “atom types” for the same atom, inspired by force fields; (iii) optimizing the basis set to improve equilibrium geometries and/or electric properties.

Heterocyclic compounds containing thiazolo and pyrimidine rings have attracted significant interest due to their diverse biological activities and structural versatility. The fusion of thiazole with pyrimidine or pyridine frameworks enhances their pharmacological potential and electronic stability. This work aimed to synthesize new heterocyclic derivatives based on benzylidene-thiazolidin-4-one scaffolds and evaluate their electronic, structural, and biological characteristics using both experimental and computational approaches. Benzylidene-thiazolidin-4-one derivatives 1 and 2 were condensed with guanidine hydrochloride to afford thiazolo[4,5-d]pyrimidin-5-amine and methyl benzoate 4. Subsequent reactions with malononitrile yielded thiazolo[4,5-d]pyrimidin-5(6H)-thione (5) and thiazolo[4,5-b]pyridine-6-carbonitrile 6. Density Functional Theory (DFT) calculations were performed to predict the molecular geometry, dipole moments, bond angles, bond lengths, and electronic properties. Reactivity and stability were evaluated from the HOMO–LUMO energy gap. Molecular docking studies were conducted to assess binding affinity with antibacterial and antimalarial protein targets. DFT analysis indicated that compound 3 exhibited the highest softness (σ = 16.129 au), whereas compound 6 behaved as a hard compound (σ = 18.519 au). HOMO electron density in compounds 3 and 5 was mainly localized on the NO₂ group (98.4–100%), while in compounds 4 and 6, it was delocalized across the dihydrothiazolo and aromatic rings. Excited states of compound (3) were assigned to π–π* transitions (λ = 208.09–223.42 nm) and n–π* transitions (λ = 255.38–324.46 nm). Molecular docking revealed strong ligand–protein interactions, including four conventional hydrogen bonds, confirming high stability and binding affinity toward antibacterial and antimalarial targets. The synthesized thiazolo[4,5-d] and thiazolo[4,5-b] derivatives demonstrated favorable electronic properties and strong protein binding affinities, suggesting their potential as promising scaffolds for antimicrobial and antimalarial drug development.

In this study, we achieve polarization and temperature-insensitive triple plasmon-induced transparency (triple-PIT) at terahertz frequencies using a novel graphene metamaterial comprising a graphene block, four graphene squares, and four graphene strips. The insensitivity of this structure to changes in the incident light's polarization angle is attributed to its high symmetry. The expressions of nth-order coupled mode theory are derived accurately, and its theoretical predictions closely align with the findings of numerical finite-difference time-domain simulations for a triple-PIT system with n = 4. Our results reveal that two synergistic single-PIT phenomena lead to a distinct and tunable triple-PIT effect in the designed metamaterial. This observation is further validated through field distribution studies. Additionally, given the continuous nature of graphene used in the metamaterial, its Fermi level and carrier mobility are easily and dynamically tunable under an applied voltage bias. Notably, the group index of the designed triple-PIT system varies between 603 and 817 as graphene's Fermi level rises from 0.8 to 1.2 eV. In contrast, the group index ranges between 778 and 1216 as graphene's carrier mobility increases from 2.5 to 4.5 m²/(V s). Moreover, the maximum group index reaches 1216 at 4.5 m²/(V s), demonstrating the potential of the system in slow-light applications. Thus, the proposed patterned graphene metamaterial and its related findings provide valuable insights for advancing optical switches, dynamically tunable modulators, multichannel filters, and high-performance slow-light devices.

Twist angle between adjacent two-dimensional (2D) materials can provide an exotic degree of freedom and lead to superior properties such as fascinating electronic structure, tunable bandgaps, and excellent carrier transport. The electronic and optical properties, and quantum capacitance of AA1 and AA2 stackings of twisted III-nitride bilayers AlN, BN, and GaN at a 21.79° twist angle are investigated by density functional theory (DFT). Compared with no-twisted systems, the twisted angle drastically reduces the band gaps of bilayer systems. The stacking mode is sensitive to the electronic structures of twisted bilayer AlN, but insensitive to the electronic structures of twisted bilayers BN and GaN. Flat bands of twisted bilayers AlN and GaN are introduced after atomic reconstruction and mainly originate from N-p states, especially for AA2 stackings of twisted bilayers AlN and GaN. Twisted bilayer BN has the strongest absorptions of 16.4% for AA1 stacking and 14.8% for AA2 stacking in the ultraviolet region. Electrical conductivity is insensitive to stacking modes, and twisted bilayer GaN possesses the strongest electrical conductivity. Different stacking modes have little impact on the electrode type of twisted bilayer materials. All systems are cathode materials at the whole voltage. Effective mass and work function are further studied.

This work presents an improved version of the residual vector correction (RVC) algorithm, designed to address the eigenproblem involved in electronic structure calculations. Instead of directly diagonalizing the entire Hamiltonian matrix, the proposed algorithm iteratively diagonalizes a 2 × 2 submatrix, focusing only on the relevant molecular orbitals. Molecular orbital energies are iteratively minimized along a residual vector, with the step size determined by diagonalizing the 2 × 2 submatrix. To obtain the subsequent eigenvalues, we employ Hotelling deflation, which constructs the necessary auxiliary Fock matrix. Since the size of the diagonalized matrix does not increase with the molecular system, this algorithm eliminates the cubic scaling dependence of computational efficiency on molecule size seen in direct diagonalization. Compared to the earlier version, the implementation within the Hartree–Fock framework shows that the current version is significantly more practical for the calculation of considerably large molecules. As demonstrated, the RVC method consistently surpasses existing iterative approaches in efficiency while maintaining high accuracy.

Lithium-ion batteries (LIBs) have dominated the energy storage field due to their high energy density, long cycle life, and environmental friendliness. In this study, we systematically investigated the electrochemical properties of phosphorus (P)-doped γ-graphyne as a promising LIBs anode material using density functional theory calculations. The formation energy and cohesive energy of γ-graphyne at varying doping concentrations are calculated, demonstrating excellent experimental synthesizability of P-doped γ-graphyne. Notably, the P-doped system exhibits enhanced electrical conductivity compared to pristine γ-graphyne. The adsorption energy of a single lithium (Li) atom on P-doped γ-graphyne is determined to be −3.72 eV, significantly higher than those of N-doped, Si-doped, and intrinsic γ-graphyne. Even with increasing Li storage, the Li adsorption energy remains greater than the cohesive energy of bulk lithium, while the average open-circuit voltage falls within the optimal range of 0–1 V, ensuring high operational safety. Remarkably, the theoretical Li storage capacity of P-doped γ-graphyne reaches 1150.68 mAh/g, which is 1.85 times that of pristine γ-graphyne and 3.09 times that of conventional graphite. Furthermore, the diffusion barrier calculations reveal that P-doped γ-graphyne substantially reduces the Li-ion migration energy barrier, indicating favorable lithium diffusion kinetics. In summary, P-doped γ-graphyne demonstrates exceptional advantages in specific capacity, structural stability, electrical conductivity, and Li-ion diffusion kinetics, providing critical theoretical insights and experimental guidance for designing next-generation high-performance LIBs anode materials.

The molecular properties of 2-(2-Bromophenyl)-1H-benzimidazole (BPBZ) were calculated using the DFT-Becke-3-Lee-Yang-Parr functional and 6-311++G(d,p) basis set. The assigned vibrational wave numbers, the observed FT-IR and FT-Raman spectra accord fairly well. Frontier molecular orbitals and Mulliken charges were used to examine the energy gap and charge transfer interaction of the molecule. The total, partial density of states (TDOS and PDOS) and overlap population density of states (OPDOS) spectra have been computed. Using natural bond orbital analysis (NBO), the intramolecular stabilization interactions of the molecule have been evaluated. The electrophilic and nucleophilic reactivity sites were examined by the molecular electrostatic potential surface and the Fukui function. We have established whether a chemical is suitable to be a drug by using molecular docking with estrogen sulfotransferase receptor (binding energy of −8.5 kcal/mol) and ADMET prediction. The molecule's cytotoxicity (IC₅₀ = 15.17 μg/mL with MCF-7 breast cancer cell line) and antibacterial properties have been done.