Structural Chemistry最新文献

The research delved into studying the anti-corrosive capabilities of newly developed antipyrine derivatives for mild steel in an acidic environment through density functional theory (DFT) and molecular dynamic (MD) simulation. The results of DFT calculations indicated that the newly designed antipyrine molecules exhibited high E_HOMO (− 4.788, − 4.908, and − 4.942) and low E_LUMO (− 2.339, − 3.109, and − 3.101) and energy gap (2.449, 1.799, and 1.841) for compound A1, A2, and A3, respectively. This suggests their propensity to transfer and accept electrons during molecular interaction with the alloy surface, promoting adsorption and corrosion protection. The antipyrine molecules were also noted to contain numerous electron-rich sites around the heteroatoms, functional groups, and inherent aromatic rings within their structures which helps in facilitating molecular interaction with the metal, leading to the adsorption, and formation of a protective layer for effective corrosion protection. High AlogP values (3.74 to 5.00) strongly indicate the molecules' hydrophilic nature, coating ability, and propensity to disperse water molecules and chloride ions in the corrosive system. The MD simulations also revealed high energy of adsorption, which follows a decreasing trend of A2 (− 161.00 kcal⋅mol⁻¹) > A1 (− 157.15 kcal⋅mol⁻¹) > A3 (− 107.93 kcal⋅mol⁻¹) indicating strong and spontaneous adsorption with a flat orientation on the Fe(110) surface. The radial distribution function (RDF) results further supported the chemosorption nature of the inhibitor molecule, and the formation of robust bonds with Fe(110) with all calculated RDF values falling below 3.5 Å. Inclusively, the investigated antipyrine compounds exhibited strong anti-corrosive properties, positioning them as promising corrosion inhibitors for mild steel deployed in acidic environments.

Porous graphenes are one of the ideal separation materials. The interaction between neopentane molecule and chemical groups N-, F-, and OH- functionalized single-layer porous graphene model (pore16) was investigated by using first-principles method. The pore size of pore16 modified by one N atom is almost the same (the difference is only 0.006 Å), while the difference of the energy barrier to neopentane is as high as 0.30 eV. For 2Npore16, the energy barrier varies by 0.88 eV, while for 4Npore16, it varies by 0.67 eV. It is evident that as the number of N atoms increases, the energy barrier widens, and this phenomenon is also found in the functionalization of F and OH. The same type and number of functional groups may have different pore sizes, which may result in very different separation properties. Interestingly, adding functionalization leads to the formation of hydrogen bonds in OHpore16, which affects the separation performance of molecule. This implies that not only pore size and shape are the main factors, but also the chemical functionalization of specific sites is the main factor. In general, this study emphasizes an important attraction might be encountered in both the design and modeling of two-dimensional membranes for separating purposes.

The [3 + 2] cycloaddition (32CA) reactions involving 6-butoxy-5,6-dihydro-4H-1,2-oxazine 2-oxide and dimethyl maleate are examined in this study. Molecular electron density theory (MEDT) is applied at the M06-2X/6-311G(d,p) level, coupled with the D3 dispersion correction. The nitronate 1 species are identified as zwitterionic entities through an analysis of the electron localization function (ELF). This 32CA reaction follows an asynchronous one-step mechanism. Conceptual DFT indices are utilized to classify dimethyl maleate as the electrophilic component and the nitronate as the nucleophilic counterpart. The [3 + 2] cycloaddition processes are predominantly governed by kinetic control, as indicated by activation free energies of − 23.6 and − 11.4 kcal.mol⁻¹ for the exo and endo pathways, respectively, aligning with experimental findings. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather polar 32CA reactions. The formation of a pseudoradical center initiates at carbon atoms C3 and C4. A subsequent docking analysis is conducted on cycloadducts 3 and 4 in relation to the main protease of SARS-CoV-2 (6LU7), alongside the co-crystal ligand. The results of this analysis reveal that cycloadducts 3 exhibit higher binding energy, while cycloadducts 4 display lower binding energy compared to the co-crystal ligand. The results confirm that the presence of isoxazolidine ring increases the affinity of the product 3.

Many 4- and 5-oxocarboxylic acids show open-cyclic solution racemization/tautomerism including the dehydration-resistant arylpyran pseudoacid 3-hydroxy-4,4-dimethylisobenzopyran-1-one. The crystal and molecular structures of nine α-anomeric derivatives (including 11 distinct molecular structures) of this pseudoacid (or close analogs) have been determined, including pseudoacyl chlorides, normal, pseudoanhydrides, a dipseudoanhydride, and a tertiary pseudoamide. The basicity of the implied exocyclic leaving groups span 40 pK units. Together with seven closely related pseudoacid molecular structures previously determined, a data set containing 18 compounds was generated. Exocyclic C–O bonds shortened as endocyclic C–O bonds lengthened in linear functions of exocyclic leaving group basicity with l(xC-O, Å) = 1.4426 − 0.00400 * pK_a, N = 13, R² = 0.969; l(nC-O, Å) = 1.4204 + 0.00205 * pK_a, N = 18, R² = 0.951. These correlations were compared with results for other α-anomeric pyranoid systems, tetrahydropyran and dihydropyran, and an arylfuran pseudoacyl system. Exocyclic substituents effectively modified endocyclic C–O bond polarities over a considerable range.

In the present work, with the aid of the density functional theory (DFT) method, we have investigated the possibility of applying the B₃S monolayer (B3SML) for sensing and adsorption of some air pollutants containing SO₂, CS₂, CO₂, CH₂O, H₂O, C₂H₂, and CF₃H from the gaseous environment. The results showed that after the adsorption of SO₂, H₂O, and C₂H₂ by B3SML, big changes took place which led to a decrease of the λ_max of each complex down to 1598.5 nm, 1418.0 nm, and 1580.0 nm, respectively. Therefore, the frequencies of the mentioned adsorption complexes rise and strong blueshifts occur. Moreover, the outcomes of the band gap estimations reveal that the B3SML could selectively detect the existence of C₂H₂ with a clearer and stronger electronic signal compared to all other gases. In addition, this nanosheet is able to sense CS₂, CH₂O, SO₂, and H₂O with good signals. Hence, it could not recognize the difference between CH₂O and SO₂ gases. Also, the results of the thermodynamic calculations indicate that B3SML would selectively adsorb and destruct SO₂, C₂H₂, and H₂O gases. Moreover, this sorbent could adsorb CH₂O and CS₂ species, but it would approximately not adsorb CO₂ and CF₃H.

To determine the effect of the embedded Cu, Ag, and Au on the electronic properties of tungsten oxides, the structures, stability, and electronic properties of the TM_n@W₁₂O₃₆ (TM = Cu, Ag and Au, n = 1–4) clusters have been investigated by using density functional theory. The results reveal that the embedded TM_n clusters decrease the structural stability of the W₁₂O₃₆ cages. The Ag@W₁₂O₃₆ and Ag₃@W₁₂O₃₆ clusters exhibit higher structural stability than other TM@W₁₂O₃₆ and TM₃@W₁₂O₃₆ (TM = Cu and Au) clusters. The Cu₃ clusters prefer to be embedded into the W₁₂O₃₆ clusters. The embedded TM_n clusters increase obviously the chemical reactivity of the W₁₂O₃₆ cages. The chemical reactivity of the Ag₂@W₁₂O₃₆ and Ag₄@W₁₂O₃₆ clusters is similar to that of the Cu₂@W₁₂O₃₆ and Cu₄@W₁₂O₃₆ clusters. The Au@W₁₂O₃₆, Au₂@W₁₂O₃₆, Ag₃@W₁₂O₃₆ and Au₄@W₁₂O₃₆ clusters display more chemical stability. The charge transfer amounts between the Ag and O atoms of the TM_n@W₁₂O₃₆ clusters are larger than those between the Cu (Au) and O atoms of them.