European Journal of Chemistry
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Theoretical insights into the structural, spectroscopic, solvent effect, reactivity, NCI, and NLO analyses of 5,7-dichloro-8-hydroxyquinoline-2-carbaldehyde
Full text linkIn this study, the characterization of the 5,7-dichloro-8-hydroxyquinoline-2-carbaldehyde molecule was carried out by nuclear magnetic resonance (1H and 13C NMR), Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis) spectroscopy and theoretical calculations in density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The integral equation formalism polarizable continuum (IEFPCM) solvation model was used for ethanol, dimethylsulfoxide (DMSO), and water solvents. The conformation of the molecule was analyzed, and the most stable structure was optimized, and the geometry and electronic structure of the optimized structure were examined. The chemical stability and charge transport inside the molecule were validated by the computed HOMO-LUMO band gap energies. Characteristics such as non-linear optic properties (NLO), charge analysis, and molecular electrostatic potential (MEP) aid in determining the electrophilic/nucleophilic nature. Compound intermolecular interactions were investigated by topological studies, including noncovalent interaction (NCI), reduced density gradient (RDG), electron localization function (ELF), and localized orbital locator (LOL). The natural bond order (NBO) analysis was used to examine the changes between the hyperconjugative interaction energy E(2) and the electron densities of the donor (i) and acceptor (j) bonds. The interaction energy, the NCI study, and the NBO analysis revealed that the ligand becomes stronger in the presence of a pyridine ring
Di-aqua-di-isothiocyanato-tin(II)-bis(18-crown-6), Sn(NCS)2·2(18-crown-6)·2H2O – A supramolecular compound of a low-valent main group element with bent sandwich architecture
Full text linkThe crystal structure of the title compound, di-aqua-di-isothiocyanato-tin(II)-bis(18-crown-6), was determined by single crystal X-ray structure analysis. The compound crystallizes in the monoclinic space group C2/c with half a molecule of the point group C2 in the asymmetric unit. The supramolecular arrangement of the three different building blocks, a bent Sn(NCS)2 one, a water molecule, and an 18-crown-6 molecule exhibits a bent sandwich-like structure with an opening angle of 48.1(1)° referring to the least-squares planes through the oxygen atoms of the crown ether molecules. Bond lengths and angles within this aggregate indicate that the isothiocyanate groups bond to the central, bivalent tin atom via covalent 2e-2c-bonds based on two orthogonal p orbitals of the metal atom, and the oxygen atoms of the water molecules via a symmetrical 3c-4e bond by use of the third metal p orbital. The crown ether molecules do not have oxygen-tin contacts but are hydrogen-bonded to the water molecules. Their conformation has similarities with that of an ideal D3d conformation
Exploring flavone reactivity: A quantum mechanical study and TD-DFT benchmark on UV-vis spectroscopy
Full text linkFlavones are known for their broad spectrum of pharmacological and biological activities, making them promising candidates for drug development and complementary medicine. In this study, a comprehensive analysis of the chemical reactivity, kinetic stability, and biological potential of the flavone molecule is performed using density functional theory (DFT) at the D3-B3LYP/6-311++G(d,p) level. The key molecular properties-proton affinity (PA), ionization energy (IE) and electron affinity (EA)-are calculated alongside global reactivity descriptors such as chemical potential (μ), chemical hardness (η), softness (σ), electrophilic index (ω), and electronegativity (χ). To ensure the reliability and cost-effectiveness of the chosen DFT method, a comparative analysis is performed using various functionals, including D3-B3LYP, wB97XD, M06-2X and MP2. Furthermore, time-dependent DFT (TD-DFT) calculations are performed with multiple functionals B3LYP, CAM-B3LYP, PBE0, M06-2X, LC-wHPBE and wB97XD to investigate the excited-state properties and UV-visible absorption spectra of flavone. The results indicate that CAM-B3LYP, M06-2X, and wB97XD provide the most accurate predictions for the absorption characteristics of the flavone molecule
Synthesis, characterization, and antimicrobial activity of Cu(II) and Zn(II) complexes with N,N-bis(4-methoxybenzylidene)ethylenediamine or N-(4-methoxybenzylidene)ethylenediamine Schiff base
Full text linkSeven mononuclear complexes were synthesized by mixing N,N'-bis(4-methoxy benzaldehyde)ethylenediamine (L) or N-(4-methoxybenzylidene)ethylenediamine (L1) and copper or zinc salts. These compounds were characterized by IR, 1H NMR, UV-vis, fluorescence spectroscopy, molar conductimetric, and elemental (CHN) analysis techniques. The crystal structures of the zinc complexes were determined by single crystal X-ray diffraction studies. Crystal data for C18H20I2N2O2Zn: Monoclinic, space group P21/c (no. 14), a = 10.45670(10) Å, b = 13.28610(10) Å, c = 15.43490(10) Å, β = 96.4300(10)°, V = 2130.86(3) Å3, Z = 4, Dcalc = 1.919 g/cm3, 46801 reflections measured (8.51° ≤ 2Θ ≤ 145.92°), 4231 unique (Rint = 0.0565, Rsigma = 0.0185) which were used in all calculations. Crystal data for C18H20Br2N2O2Zn: Monoclinic, space group P21/c (no. 14), a = 10.30071(17) Å, b = 13.00839(18) Å, c = 15.0084(2) Å, β = 97.3057(14) °, V = 1994.74(5) Å3, Z = 4, Dcalc = 1.737 g/cm3, 103282 reflections measured (4.158° ≤ 2Θ ≤ 59.492°), 5360 unique (Rint = 0.0394, Rsigma = 0.0161) which were used in all calculations. Crystal structures show a distorted tetrahedral geometry around the zinc metal. The ligand is bidentate chelating with imine nitrogen atoms. Fluorescence spectroscopy shows a reduction in the fluorescence intensity of the complexes relative to the ligand. This reduction is due to the presence of metal-coordinated halides. The in vitro antimicrobial activities of the ligand and complexes were elaborated by screening them against Gram(+) bacteria (Streptococcus pyogenes), Gram(-) bacteria (Pseudomonas aeruginosa), and a fungus (Candida albicans). All compounds showed weak activity against the tested bacterial and fungal strains
Synthesis, analysis of single crystal structure and computational studies on a novel picrate derivative: 2-(Pyridine-2-ylthio)pyridine-1-ium picrate
Full text linkA new organic salt, 2-(pyridine-2-ylthio)pyridine-1-ium picrate (C16H11N5O7S: 2-PyrTPPc), has been synthesized and characterized using various spectroscopic methods such as 1H NMR, 13C NMR, and FT-IR. The crystal structure of the title compound was analyzed using X-ray structure analysis, which revealed that it belongs to the monoclinic P21/c space group with a = 16.876(4) Å, b = 7.6675(18) Å, c = 13.846(3) Å, Z = 4, and V = 1766.9(7) Å3. The molecular packing of the compound showed the presence of several intermolecular hydrogen bonds between different atoms. The electronic properties of the crystal were investigated using density functional theory (DFT) with B3LYP/6-311G(d,p) level. Frontier molecular orbitals were drawn and related global quantities such as electronic chemical potential, chemical hardness-softness, electrophilicity, HOMO and LUMO energy eigenvalues, and the difference between HOMO and LUMO (∆E) were calculated and discussed. TG/DTG analysis revealed the thermal stability of the 2-PyrTPPc crystal. The single stage of decomposition and the sharpness of the peak in the temperature range of 157-224 °C illustrated the purity and good crystallinity of the grown crystal. The different vibration modes of the 2-PyrTPPc molecule were determined by analyzing the FT-IR and FT-Raman spectra. The detection of vibrations of the pyrNH+ and aromatic thioether moiety supports the confirmation of the di(pyridin-2-yl)sulfane structure through the intermediate formed by the transfer of the proton from picric acid to 2-mercaptopyridine
Synthesis, crystal structure, and Hirshfeld surface analysis of a cubane-type tetranuclear polyoxotitanate cluster
Full text linkA cubane-type tetranuclear polyoxotitanate cluster derived from 8-(isopropoxycarbonyl)-1-naphthoic acid is reported which is synthesized under reflux conditions in isopropanol (HOiPr). The ligand 8-(isopropoxycarbonyl)-1-naphthoic acid (INA) was generated in situ from 1,8-naphthalic anhydride and isopropyl alcohol in the reaction mixture where one of the carboxylate groups of 1,8-naphthalene dicarboxylic acid (generated from the ring opening reaction of 1,8-naphthalic anhydride) forms isopropyl ester by reacting with solvent isopropoxide. The solid-state structural elucidation of the cluster is achieved through the single crystal X-ray diffraction method, providing detailed insights into their molecular arrangements. Crystal data for C72H80O24Ti4: Triclinic, space group P-1 (no. 2), a = 19.086(3) Å, b = 20.341(4) Å, c = 21.538(4) Å, α = 88.895(4)°, β = 72.158(4)°, γ = 89.049(4)°, V = 7958(3) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.457 mm-1, Dcalc = 1.269 g/cm3, 64356 reflections measured (4.42° ≤ 2Θ ≤ 54.94°), 34455 unique (Rint = 0.0458, Rsigma = 0.0752) which were used in all calculations. The final R1 was 0.0603 (>2sigma(I)) and wR2 was 0.1558 (all data). In the crystal lattice, the asymmetric unit of the cluster contains two molecules. Various types of supramolecular interactions such as C-H···O, C-H···π, π···π and unusual O···O interactions are observed in the X-ray structures. All these interactions guide the formation of 3D supramolecular architecture in the solid state of the compound. In addition to these, 2D fingerprint (2D-FP) and Hirshfeld surface analysis (HSA) computations were used to prove and quantify various supramolecular interactions within the crystal lattice
Unified formulae for augmented near orthonormalized STO-kG (1s, …, 4f) basis sets via atomic orbital energy fit with graphical representations to use in molecular structure calculations
Full text linkSTO-kG type (linear combination of k Gaussians) basis functions for 1s to 4f Hydrogen-like orbitals by ‘energy fit’ are reported as simple functions of the atomic number Z and quantum numbers to utilize in molecular electronic structure calculations. We analyze how they reproduce the one-electron atomic wave function shapes and energy values (-Z2/(2n2)) as an obvious primary claim along with reproducing the nodes exactly. The literature STO-kG yields a huge number of tables for different atoms in the periodic table; in contrast, our sets contain Z as a parameter yielding a compact list. A ‘variation-like’ property is also discussed for excited states (2s and up). The optimizations have been done by using least squares fits via the Lagrange multiplier method for energy with a constraint for normalization. All these STO-kG basis functions are normalized exactly to one in our tables. The general problem of STO-kG(3 and 4du^2) and STO-kG(4fu^3 and 4fuv^2) basis functions among the six technical 3duv as well as the ten technical 4f used in practice is commented on. In relation and comparison, the Gaussian package STO-kG basis set is commented on