Structural Chemistry最新文献

Derivatives of aryl and hetero-aryl substituted oxazoles have several uses in agrochemicals, pharmaceuticals, and nonlinear optics (NLO). This study reports the synthesis and non-linear optical response (NLO) of three new compounds, viz., 2-(naphthalen-2-yl) oxazole (NTOZ), 2-(4-phenoxyphenyl) oxazole (PPOZ), and 2-(4'-bromo-2,2',6,6'-tetramethyl-[1,1'-biphenyl]-4-yl) oxazole (BMPOZ), for the first time by the palladium-catalyzed Suzuki coupling method. The structures of synthesized products were clarified by employing spectroscopic investigations using ¹H, & ¹³C-NMR, FT-IR, and UV-visible. The DFT studies were conducted at the M06/6-31G (d,p) functional to visualize NLO properties. Various analyses, including frontier molecular orbitals (FMOs), natural bond orbitals (NBOs), transition density matrix (TDM), and density of state (DOS), were conducted to learn more about the NLO response of the aforesaid compounds. The results indicated that the NTOZ compound showed the lowermost band gap (4.764 eV) and uppermost bathochromic shift (307.257 nm) amongst NTOZ, PPOZ, and BMPOZ. Results of global reactivity correspond with FMO outcomes such as NTOZ with a lower band gap, which displayed lower hardness (2.382 eV) and higher softness (0.2099 eV) data. Owing to the unique properties of NTOZ, significant NLO responses such as β_total = 1.3227 D and β_total = 5.47910^–30 esu were investigated, indicating it is an effective NLO material.

A DFT (density functional theory) investigation using the generalized gradient approximation BP86 and the hybrid B3LYP functionals and TZP basis set is dealing with the bonding, the electronic structure and the interaction types occurred within the XCuL’ and (LCuL’)⁺ (X = Cl, CH₃, CN, CF₃, L = CO, NH₃, PH₃, and L’ = C₂H₂, C₂H₄, C₄H₆, C₆H₆, and NHC) complexes. The optimized structures and energy decomposition analysis of XCuL’ and (LCuL’)⁺ complexes were employed to provide a relationship between the bond lengths, the X-Cu-L’ and L-Cu-L’ bond angles, the Wiberg indices, the Mayer bond orders, interaction energies, and the Cu-L’ bonding character. The energy decomposition analysis indicates that the interactions occurred for various L’ ligands are more electrostatically than covalently bonded to the Cu(I) center formally of + I oxidation state. The different contributions stemming from electrostatic and orbital interactions are significant, in relationship with the ionic and covalent characters, respectively. The contribution from σ-donation to the bonding energy was found more important for the NHC ligand than the alkene and alkynes ones. However, the contribution from π-back-donation was found to be comparable for all complexes. The σ-bonding contributes more than 50% into the total orbital interaction overtaking those of π type, in accordance with the population of the copper 4s orbital, particularly in the presence of C₆H₆ and NHC ligands. The interactions in all complexes exhibit comparable deformation densities and NOCV orbital shapes. Besides, it has been shown that the ΔE_prep contributes weakly in the deformation of the interacting fragments as well as the BSSE correction which impacts weakly or negligibly the interactions between the fragments composing different XCuL’ and (LCuL’)⁺ complexes.

This study explores the nonlinear optical (NLO) properties of hexamine (HMT) doped with transition metals scandium (Sc) and titanium (Ti), exhibiting enhanced NLO responses for advanced photonic devices. Employing ωB97XD functional for optimization and calculations, the study examines geometric parameters, electronic excitation, exciton binding energy (E_b), and vertical ionization energy (VIE) using DFT and TD-DFT. High VIE (3.25 to 4.52 eV) indicates enhanced stability in doped systems. The HOMO-LUMO gap decreases from 10.69 eV in pure HMT to 3.30 to 4.85 eV in the designed systems. These systems exhibit thermodynamic stability with binding energies 3.51 to 4.27 kcal/mol, and Ti-HMT-Ti being the most stable. A two-level approximation method is utilized to determine linear polarizability and nonlinear first and second hyperpolarizability (α_static, β_static, γ_static), which exhibits the highest γ_static (6546.63 au) value of Sc-HMT-Sc. Orbital transitions, charge distribution, electrophilicity, and nucleophilicity are examined using TDM, EDDM, and ESP, respectively. PDOS and TDOS provide insights into HOMO-LUMO gap reduction, NCI identifies the weak interactions and broadened and red-shifted UV absorption spectra, all are in the favour of NLO response of designed complexes. So, these materials show exceptional NLO properties and promising for optoelectronic applications.

In this study, we employ density functional theory to investigate KXH₃ (X = Ca, Sc, Ti, & Ni) hydride perovskites for H2 storage applications. Lattice parameters calculated using GGA-PBE are 4.482 Å, 4.154 Å, 3.974 Å, and 3.686 Å for KCaH₃, KScH₃, KTiH₃, and KNiH₃, respectively. Electronic structure analysis shows KScH₃, KTiH₃, and KNiH₃ are metallic, while KCaH₃ is a semiconductor. Strong bonding and long bond lengths indicate high hydrogen storage potential. The materials exhibit thermodynamic and mechanical stability, suggesting feasibility for experimental synthesis. Gravimetric analysis reveals promising hydrogen storage capacities: 3.646 wt% (KCaH₃), 3.452 wt% (KScH₃), 3.346 wt% (KTiH₃), and 3.005 wt% (KNiH₃). Calculated hydrogen desorption temperatures range from 442.40 K to 614.82 K, indicating suitability for practical hydrogen storage applications. These findings highlight the potential of KXH₃ (X = Ca, Sc, Ti, & Ni) perovskites as effective hydrogen storage materials.

To delve into the microscopic property of the cluster RhSi_n (n = 6–15), this study employs the CALYPSO structure prediction program and density functional theory. The paper conducts a comprehensive theoretical analysis of the clusters, examining parameters such as structures, relative stabilities, charge transfer, vertical electron affinity, vertical ionization potential, chemical potential, chemical hardness, and infrared and Raman spectra. The optimization process reveals that the rhodium doping has clearly changed the structures of silicon clusters. The ground state geometries favor Rh-linked framework beginning from n = 6, and they favor Rh-encapsulated Si cages when n approach 10. RhSi₁₃ cluster is more stable than its neighbors. The charges transfer within the clusters always transfer from silicon atom to rhodium atom, and there is spd hybridization in RhSi_n cluster. The analyzed chemical potential and chemical hardness pointed out the RhSi₁₃ cluster has the stronger hardness than other clusters. At last, the infrared and Raman spectrum properties for RhSi₁₃ cluster are analyzed.

Based on the template-assisted cyclocondensation procedure, two Schiff-base macrocyclic mononuclear lanthanide complexes (Pr-2_l and Nd-2_l) with the “lasso-type” architecture have been synthesized. According to X-ray structure analysis, the central ten-coordinate lanthanide ions (Pr³⁺ and Nd³⁺) in two complexes have distorted bicapped square antiprism geometry, and this geometry is completely encircled by two axial chelating nitrates on each side of the 23-membered macrocyclic plane and six donors in the macrocyclic skeleton. With the higher relatively inhibitory rates, the complex Pr-2_l can show significant antimicrobial activities against C. albicans and MRSA with lower MIC values (7.81 and 3.91 μg·mL⁻¹), while complex Nd-2_l exhibited good antimicrobial activities for S. aureus, C. albicans, and MRSA whose MIC values are 1.95, 7.81, and 3.91 μg·mL⁻¹. This current work is believed to provide another practical approach to further construct new antimicrobial materials by the use of Schiff-base and lanthanide antimicrobial fragments.

Using the B3LYP-D3 functional and the 6-311++G(d,p) basis set, the fluoride (F⁻), chloride (Cl⁻), bromide (Br⁻), cyanide (CN⁻), nitrate (NO₃⁻), and sulfate (SO₄²⁻) affinities of perfluorocubane (PFC) was theoretically investigated. This anion receptor interacts to the selected anions by LP → σ* interactions. It was discovered that the charge distribution in a small radius and net charge value in anion have a significant impact on the anion affinities of PFC structure. The natural bond orbital (NBO) analysis was used for identifying the detailed characteristics of anion… PFC interactions. The ∆H value of anion affinity of PFC for F⁻, Cl⁻, Br⁻, CN⁻, NO₃⁻, and SO₄²⁻ was calculated as − 139.36, − 63.53, − 50.30, − 66.64, − 46.21, and − 151.28 kJ mol⁻¹, respectively. The obtained results show that the anion affinity of PFC for SO₄²⁻ and F⁻ are among the strong organic anion receptors.

Two lanthanide coordination polymers (CP) of Nd(III) and Tb(III) with 2,4,6-pyridinetricarboxylate ligands were synthesized by reacting Nd(III) or Tb(III) chlorides with 2,4,6-pyridinetricarboxylic acid (H₃ptc) by hydrothermal method at 180 °C. Their chemical formulas were {[Nd(ptc)(H₂O)₂]·H₂O}_n (CP-1) and {[Tb(ptc)(H₂O)₃]·H₂O}_n (CP-2). Two compounds were characterized by IR spectra and element analyses. The crystal structures were determined by X-ray single crystal diffraction. CP-1 formed three-dimensional (3D) structure by the connections of coordination bonds between Nd(III) and ptc ligands and CP-2 formed two-dimensional (2D) layered structure. They could produce the characteristic f-f transition luminescence of Nd(III) or Tb(III) ion with the excitations of UV-rays. The lifetime for ⁵D₄ excited state of Tb(III) in CP-2 was 741 μs. And the absolute quantum yield of photoluminescence for CP-2 can reach 60% (λ_ex = 295 nm).