International Journal of Quantum Chemistry最新文献

Co-delivering FDA-approved drugs can be less harmful and boost biological activity by targeting different protein mechanism at same time. Gemcitabine and 5-Fluorouracil (GE5F) adduct work together to destroy cancer cells and increase the efficacy in the fight against breast cancer. The basis set B3LYP/6-311 G was utilized in this investigation to improve the structure of GE5F adduct. The natural bond analysis exhibited the intermolecular interactions of the GE5F adduct. Electronic transitions were seen to be π → π*, and theoretical calculations were performed for the ultraviolet to visible spectrum. The energy gap between HOMO and LUMO was used to study the GE5F adduct's structural stability and reactivity; the computed energy gap (ΔE) was 3.912 eV. The Mulliken charge population was assessed and the complex structure's electrostatic potential was established. Weak interactions of the GE5F were assessed using RDG analysis, and topological aspects were investigated using LOL and ELF analysis. Investigating the GE5F adduct's adsorption, distribution, metabolism, excretion, and toxicity properties, the results confirmed that GE5F adduct comes under the safety parameters being a drug-likeness molecule. Molecular docking experiments were conducted using target proteins for breast cancer. The complex molecule had a higher binding affinity as indicated by the docking scores, which validated the better combinatorial interaction between gemcitabine and 5-Fluorouracil. With − 9.4 kcal/mol, the complex molecule's strongest binding capacity was against PARP protein, and stable confirmation was observed through molecular dynamic simulation for 100 ns with four hydrogen bond interactions. These in silico finding will pave a way for in vitro and in vivo experiments with better enhancement of FDA approved drugs.

The current investigation employs first-principles DFT (density functional theory) calculations to examine the influence of transition metal replacements on the structural, thermodynamic, and thermoelectric properties of Cu-based chalcogenides TMCu₃Se₄ (TM = Nb/Ta/V). The PBE-generalized gradient approximation (GGA) model is utilized to compute the fundamental properties of Cu-based chalcogenides under study. A thorough examination of the energy band structures indicates that these chalcogenides are semiconductor compounds with indirect energy bandgaps. We can infer from the calculated energy band structures that the bandgap values are 1.67, 1.77, and 1.05 eV for NbCu₃Se₄, TaCu₃Se₄, and VCu₃Se₄, respectively. The $��{\mathrm{ZT}}_e�$ values for NbCu₃Se₄, TaCu₃Se₄, and VCu₃Se₄ are 0.661, 0.998, and 0.996, respectively. These values make them highly appropriate for usage in thermoelectric (TE) devices. The thermoelectric characteristics of pyrochlore oxides TMCu₃Se₄ (TM = Nb/Ta/V) suggest that these materials have promising potential for energy-related applications. The analyzed thermodynamic properties demonstrate that the Cu0based chalcogenide materials TMCu₃Se₄ (TM = Nb/Ta/V) exhibit a notable level of thermal stability.

Cluster formation has significant implications in atmospheric science and environmental chemistry. These clusters are characterized by complex interactions between their constituents, which influence their structure, stability, and growth. Experimental investigations are difficult for the initial stages of prenucleation cluster formation, which leads to larger aerosols. To understand the formation of clusters, the interactions between sea salts (NaCl, KCl, and MgCl₂), water, and sulfuric acid molecules have been investigated. Each step has been comprehensively examined and thermodynamic parameters have been computed using DLPNO-CCSD(T)/CBS//M06-2X/6-311++G(3df,3pd) to find the stabilities of the molecular complexes. Among all complexes, the binding energies of cluster (SS)₁(W)₁(SA)₃ are found to be the lowest due to the formation of HCl, hydrogen bonding, and weak van der Waal forces. Sea salts have shown a more favorable interaction with H₂SO₄ compared to H₂O molecules. The addition of H₂SO₄ increases the reactivity of the cluster (SS)₁(W)_n, while the addition of H₂O molecules reduces the reactivity of the cluster (SS)₁(SA)_n. However, further addition of H₂SO₄ or H₂O to the existing cluster (SS)₁(W)_n(SA)_n increases the free energy of formation. Furthermore, the influence of temperature was also investigated, suggesting that complex formation is slightly more favorable at lower temperatures than at higher temperatures. The negative values of thermodynamic parameters indicate, that these complexes are spontaneous and exothermic over the colder regions.

In this work, we have studied the torquoselectivity of a set of unusual ring-opening electrocyclic reactions that have not been successfully rationalized using models based on orbital symmetry nor have they been explained by steric hindrance. Firstly, the corresponding transition states have been obtained, and it has been verified that the intrinsic reaction coordinates associated with these transition states are consistent with the reactants and products of the reactions studied. This has allowed us to theoretically calculate the reaction barriers (with their corresponding thermal corrections) and compare them with the corresponding experimental values. In a second step, we have analyzed the electronic bonding structure using the methodologies of Natural Bond Orbital Analysis and Quantum Theory of Atoms in Molecules, searching for interactions that may significantly stabilize the transition states. Finally, we have analyzed the reactivity using a recent model that has allowed us to calculate the corresponding bond reactivity descriptors.

The problem of whether and how the captodative aromatic systems with the donor and acceptor substituents at the same carbon atom of the C=C bond can be more stable than the π-conjugated push-pull counterparts with the two substituents in the vicinal position is analyzed for cyclopentadienyl derivatives possessing an aromatic cyclopentadienyl ring. The analysis of electronic, magnetic, and structural criteria of aromaticity showed that among typical organic donors, such as amines NR₃, ethers R₂O, guanidine (NH₂)₂C=NH, siloxane O(SiH₃)₂, silatrane, the captodative isomers [cyclopentadienylium]⁻C(X⁺) = CH₂ can be more stable than their push-pull isomeric counterparts [cyclopentadienylium]⁻—CH=CH—X⁺. The largest energy difference in favor of the former was found to be ca. 13 kcal/mol for X = NH=C(NH₂)₂.

Cross-linked polyethylene (XLPE) insulation has been used in most advanced power cable technology. Strategies for decreasing the amount of antioxidants have been proposed to reduce conductivity further. In this study, the structural design of a new dual-functional antioxidant has been established. Theoretical investigation of the antioxidative behavior and grafting reaction of the new antioxidant by ultraviolet (UV) radiation was performed using the density functional theory (DFT) method. The reaction potential energy information of the six reaction channels at the B3LYP/6-311+G (d,p) level was obtained. Frontier molecular orbitals (MOs) and natural bond orbital (NBO) charge populations of the designed antioxidant molecule were analyzed. The calculation results indicate that the reaction Gibbs energy barrier of the designed antioxidant and O₂ required to achieve the antioxidative effect is about 0.8 eV lower than that of the polyethylene chain. Moreover, due to the lower reaction Gibbs energy barrier, the reaction active site of the designed antioxidant accepting H is located on the O of the CO groups. The proposed mechanism would be beneficial to understanding the molecular functions of antioxidants and further broadening the design ideas of thermoplastic insulation materials for future advanced power cables.

In double-stranded DNA, a rapid deprotonation of guanine radical cation (G^•+) hinders the long-distance transfer of positive charge (hole). It is significant to explore the proton transfer of G^•+ for designing other DNA structures with high electrical conductivity. The deprotonation of G^•+ is explored in the 1H₂O, 2H₂O, 3H₂O, and 9H₂O models by quantum mechanics (QM) method. The results indicate that the second hydration shell facilitates proton transfer. The QM/molecular mechanics (MM) (ABEEM) method accurately simulates polarization and charge transfer effects through the implementation of the reactive valence-state electronegativity piecewise functions and setting local charge conservation conditions. The QM/MM(ABEEM) method has been developed to investigate the 9H₂O model. The obtained activation energy (16.3 ± 0.8 kJ/mol) through molecular dynamics simulations is consistent with experimental data (15.1 ± 1.5 kJ/mol), demonstrating the accuracy of the QM/MM(ABEEM) method in simulating proton transfer in the DNA system. The deprotonation rate of G^•+ in the free base (1.5 × 10⁷ s⁻¹) is faster than that of G^•+ within double-stranded DNA (10⁶–10⁷ s⁻¹), which indicates that the free G base is an avoidable participant when designing hole transfer carrier due to its rapid deprotonation rate. Concurrently, the relationship between the proton transfer distance and potential barrier is monotone increasing, meaning that the long-range proton transfer corresponds to high energy barrier. The molecule involved in long-range proton transfer of G^•+ is more suitable as DNA electronic devices. This research provides valuable microscopic insight into deprotonation to advance the advancement of DNA structures with high electrical conductivity.

Imidazole structures are significant molecular frameworks in pharmaceutical and energetic material research. The synthesis efficiency and yield of their derivatives often vary greatly, making it challenging to establish reaction regularity. In this study, we investigated two types of imidazole derivatives with notably different synthesis efficiencies and yields. Our findings reveal that the catalysis of H₂O molecules is crucial for ensuring synthesis efficiency, while side reactions are influenced by the acidity of the solution during the process, thereby affecting the synthesis yield. We observed that the energy barrier for the H₂O-catalyzed ipsilateral H transfer process was reduced to 12.0 from 40.1 kcal/mol, significantly enhancing the reaction efficiency. The synthesis of 34-dihydroxyimidazolidine-2-ketone was found to have a low yield of 19.2% due to competitive side reactions in the reaction system, which have higher energy barriers compared to the desired synthesis pathway. These findings provide a theoretical foundation for future research to optimize the synthesis of imidazole derivatives. Enhancing synthesis conditions could significantly benefit pharmaceutical applications and the development of advanced energetic materials.