One-Dimensional Hydrogen-Bonded N–H…O in the Hybrid Phosphate: Hirshfeld Surface Analysis and DFT Quantum Chemical Calculations

In the present work the 3D-supramolecular network is stabilized by N–H…O and O–H…O hydrogen bonds, by O…N interactions involving the organic cation and inorganic anion as checked by Hirshfeld surface analysis. The van der Waals contacts play a key role in the consolidation of the packing of 4-chloro-2-methylanilinium dihydrogenphosphate[4-CMDHP] structure. In order to support experimental results, density functional theory calculations have been performed using B3LYP functional with 3-21 G basis set. All of the obtained theoretical results are in a perfect agreement with the experimental ones. Furthermore, nonlinear optical behavior of 4-CMDHP has been investigated by determining the Hirshfeld surface, density of states and HOMO-LUMO energy gap using the same basis set. Finally, the molecular electrostatic potential surface of 4-CMDHP molecule was simulated and discussed.

DFT Calculations and Molecular Docking Studies on a Chromene Derivative

Chromenes and their derivatives have been considered as an important class of oxygen-containing heterocycles. There has been an increasing interest in the study of chromenes due to their biological activity. Herein, the structural, electronic, and vibrational properties of a chromene derivative, entitled 2‐amino‐5‐oxo‐4‐phenyl‐4,5‐dihydropyrano[3,2‐c]chromene‐3‐carbonitrile and abbreviated as Chrom-D, have been reported. The FT-IR, UV-vis, and 1H-NMR and 13C-NMR chemical shifts’ measurements were recorded. The molecular geometry and the vibrational frequencies are computed in the frame of density functional theory at the B3LYP/6-311++G(d,p) level of theory. The noncovalent interactions in the crystal lattice which are responsible to the 3D crystal structure of Chrom-D are investigated based on Hirshfeld surfaces and topological reduced density gradient (RDG) analysis. Molecular electrostatic potential surface, Mulliken charges, and Fukui functions are computed in order to find out the electrophilic and nucleophilic sites. The electronic properties of the title compound have been studied based on the TD-DFT calculations. Finally, Chrom-D has been evaluated as a multifunctional agent against Alzheimer’s disease (AD).

Molecular modelling, spectroscopic characterization and nonlinear optical analysis on N-Acetyl-DL-methionine

In this present methodical study, on the basis of the density functional theory (DFT), the first-principles calculations have been employed successfully to study the structural and electronic properties of N-acetyl-DL-methionine (C7H13NO3S) which is a derivative of DL-methionine which is also known DL-2-amino-4-methyl-thiobutanoic acid. Optimized molecular structure, vibrational frequencies and also 13C and 1H NMR chemical shift values of the title compound are provided in a detailed manner by using B3LYP and HSEH1PBE functionals by applying 6-311++G(d,p) basis set for calculations using Gaussian 09W program. The comparison of the calculated values with the experimental values provides important information about the title compound. In addition, the electronic properties (UV-Vis calculations) of the title compound, such as HOMO-LUMO energy values and energy gap, absorption wavelengths, oscillator strengths were performed basing on the optimized structure in gas phase. Moreover, the molecular electrostatic potential surface, dipole moment, nonlinear optical properties, linear polarizabilities and first hyperpolarizabilities and chemical parameters have also been studied.

Crystal structure and Hirshfeld surface analysis of (2E,2′E)-1,1′-[selenobis(4,1-phenylene)]bis[3-(4-chlorophenyl)prop-2-en-1-one]

In the title compound, C30H20Cl2O2Se, the C—Se—C angle is 99.0 (2)°, with the dihedral angle between the planes of the attached benzene rings being 79.1 (3)°. The average endocyclic angles (Se—C—C) facing the Se atom are 122.1 (5) and 122.2 (5)°. The Se atom is essentially coplanar with the attached benzene rings, deviating by 0.075 (1) and 0.091 (1) Å. In the two phenylene(4-chlorophenyl)prop-2-en-1-one units, the benzene rings are inclined to each other by 44.6 (3) and 7.8 (3)°. In the crystal, the molecules stack up the a axis, forming layers parallel to the ac plane. There are no significant classical intermolecular interactions present. Hirshfeld surface analysis, two-dimensional fingerprint plots and the molecular electrostatic potential surface were used to analyse the crystal packing. The Hirshfeld surface analysis suggests that the most significant contributions to the crystal packing are by C...H/H...C contacts (17.7%).

Crystal structure and Hirshfeld surface analysis of 4-(2,6-dichlorobenzyl)-6-phenylpyridazin-3(2H)-one

The asymmetric unit of the title compound, C17H12Cl2N2O, contains one independent molecule. The molecule is not planar, the phenyl and pyridazine rings are twisted with respect to each other, making a dihedral angle of 29.96 (2)° and the dichlorophenyl ring is nearly perpendicular to the pyridazine ring, with a dihedral angle of 82.38 (11)°. In the crystal, pairs of N—H...O hydrogen bonds link the molecules to form inversion dimers with an R 2 2(8) ring motif. The dimers are linked by C—H...O interactions, forming layers parallel to the bc plane. The intermolecular interactions were investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, and the molecular electrostatic potential surface was also analysed. The Hirshfeld surface analysis of the title compound suggests that the most significant contributions to the crystal packing are by H...H (31.4%), Cl...H/H...Cl (19.9%) and C...H/H...C (19%) contacts.

Crystal structure and Hirshfeld surface analysis of two 5,11-methanobenzo[g][1,2,4]triazolo[1,5-c][1,3,5]oxadiazocine derivatives

In the title compounds, 9-bromo-2,5-dimethyl-11,12-dihydro-5H-5,11-methanobenzo[g][1,2,4]triazolo[1,5-c][1,3,5]oxadiazocine, C13H13BrN4O (I), and 7-methoxy-5-methyl-2-(pyridin-4-yl)-11,12-dihydro-5H-5,11-methanobenzo[g][1,2,4]triazolo[1,5-c][1,3,5]oxadiazocine, C18H17N5O2 (II), the triazole ring is inclined to the benzene ring by 85.15 (9) and 76.98 (5)° in compounds I and II, respectively. In II, the pyridine ring is almost coplanar with the triazole ring, having a dihedral angle of 4.19 (8)°. In the crystal of I, pairs of N—H...N hydrogen bonds link the molecules to form inversion dimers with an R 2 2(8) ring motif. The dimers are linked by C—H...π and C—Br...π interactions forming layers parallel to the bc plane. In the crystal of II, molecules are linked by N—H...N and C—H...O hydrogen bonds forming chains propagating along the b-axis direction. The intermolecular interactions were investigated using Hirshfeld surface analysis and two-dimensional fingerprint plots, and the molecular electrostatic potential surface was also analysed. The Hirshfeld surface analysis of I suggests that the most significant contributions to the crystal packing are H...H (42.4%) and O...H/H...O (17.9%) contacts. For compound II, the H...H (48.5%), C...H/H...C (19.6%) and N...H/H...N (16.9%) interactions are the most important contributions.

Experimental and quantum chemical studies on the structure and vibrational spectra of cearoin (a neoflavonoid)

In the present investigation, the natural product cearoin is studied by both experimental and theoretical methods. It is classified as a family of neoflavonoid and is widely used as a local anti-inflammatory, antibiotic, and antiallergic substance. To obtain detailed information about the discussed molecule, a number of experiments have been performed by various techniques including infrared, Raman, and ultraviolet–visible spectroscopy. Quantum chemical calculations were also performed for a clear interpretation and analysis of the results. HOMO–LUMO energy band gap gives a valuable understanding of the reactivity and some of the structural and physical properties of the theme molecule. Molecular electrostatic potential surface, global and local reactivity descriptors are used to study the chemical reactivity of the molecule. Natural bond orbital analysis is followed to figure out the stability of the molecule arising from hyperconjugative interactions and charge delocalization. As cearoin is utilized as an antibiotic material, molecular docking simulations have also been done on bacterial proteins to investigate the ligand–protein interaction.