Potential Energy Distribution Study Of Beta Asarone and its Vibrational Spectrum and Force Constants

The PED assignments are analysed for the title molecule. The Force Constants and Reduced masses are presented for reference. Vibrational assignments are made to the title molecule Beta Asarone. .The analysis of Vibrational Assignments is done with an intention to deduce the various properties of Beta Asarone that should aid in analysing the reported toxicity of Beta Asarone.

Vibrational Spectral Studies, Quantum Mechanical Properties, and Biological Activity Prediction and Inclusion Molecular Self-Assembly Formation of N-N’-Dimethylethylene Urea

A cyclic urea analog, N-N'-dimethylethylene urea, was studied using different spectral methods like FT-IR, FT-Raman, and UV-VIS methods followed by computational simulations. The experimental and simulated spectra are compared, and a detailed assignment of vibrations and potential energy distribution is made. It was followed by various quantum mechanical studies like frontier orbital analysis, energy descriptors, average local ionization energies, and nonlinear optical properties. The NBO gave an insight into the various intramolecular stabilizing electron delocalization by hyperconjugation. Noncovalent interaction analysis provided various types of interactions present in the molecule. We also studied ALIE, local information entropy, electron localized function, reduced density gradient studies, localized orbital locator studies, and other analyses. Molecular docking results indicated that this urea derivative acted as an ATP-hydrolysing inhibitor, and the drug delivery ability of cyclodextrin on NND was tested by forming an inclusion complex with both compounds with dispersion and without dispersion interaction.

Molecular Geometry, Vibrational Spectroscopic, Molecular Orbital and Mulliken Charge Analysis of 4-(Carboxyamino)-Benzoic Acid: Molecular Docking and Dft Calculations

Structure based biological and chemical properties of 4-(carboxyamino)-benzoic acid has been studied by quantum chemical methods. The revamped geometric structure and its quantum chemical parameters were obtained by DFT-B3LYP/6-311G method. Normal mode analysis is performed to assign the fundamental vibrational frequencies as per the potential energy distribution (PED) by using the VEDA program. Simulation of IR and Raman spectral patterns are observed by refinement of scale factors. TD-DFT approach is used to explore the excited states of molecule and prediction of electronic absorption spectra. NMR chemical shifts of the molecule are determined by the gauge independent atomic orbital method. The molecular docking is performed to recognize the binding energy of the ligand with the dynamic site of protein. In our docking analysis, the protein 5DT6 shows the best results than other three proteins which could be used for further analysis. Further inter and intra molecular interactions, electrophilic, nucleophilic and chemical reactivity sites are found by molecular electrostatic potential, HOMO-LUMO and Global chemical reactivity descriptors. Thermodynamic property of the title compound is also reported. The determined quantum chemical parameters show high reactivity and the dipole moment was sufficiently high enough to induce nonlinear characteristics which are required for applications in optoelectronic devices.

Electronic structure theory study of the reactivity and structural molecular properties of halo-substituted (F, Cl, Br) and heteroatom (N, O, S) doped cyclobutane

Cyclobutane and its halo-substituted derivatives and its heteroatom doped derivatives have been extensively investigated in this study because of the vast applications and interesting chemistry associated with them, the vibrational assignments, Natural Bond Orbital (NBO) analysis, Conceptual Density Functional Theory, Quantum Mechanical Descriptors and Molecular Electrostatic Potential (MEP) analysis have been explored in this study. The corresponding wavenumbers of the studied compounds have as well been assigned by Potential Energy Distribution analysis. Several inter and intramolecular hyperconjugative interactions within the studied compounds have been revealed by the NBO analysis with a confirmation of geometric hybridization and electronic occupancy. The compounds reactivity was observed to decrease down the halo group in manners such as the stability, both were observed to decrease from azetidine to thietane. The distribution of charge was observed to be affected by the ring substituent as observed from the charge population analysis; in addition, adjacent atoms are very much affected by the inherent properties of the substituted atoms. The NBO result suggests that the molecules are stabilized by lone pair delocalization of electrons from the substituted atoms and molecular electrostatic potential (MEP) studies revealed that substituted halogens and doped heteroatoms are important and most probable sites of electrostatic interactions.

Molecular Structure, Homo-Lumo and Vibrational Analysis Of Ergoline By Density Functional Theory

In this work, quantum chemical study on a natural product ergoline has been presented using density functional theory (DFT) employing 6-311++G(d,p) basis set. A complete vibrational assignment has been performed for the theoretical FT-IR and Raman wavenumbers along with the potential energy distribution (PED) with the result of quantum chemical calculations. The structure–activity relationship has been interpreted by mapping electrostatic potential surface (MEP). Graphical representation of frontier molecular orbitals with their energy gap have been analyzed theoretically for both the gaseous and solvent environment employing time dependent density functional theory (TDDFT) employing 6-31G basis set.

DFT CALCULATION AND RAMAN SPECTROSCOPY STUDIES OF α-LINOLENIC ACID

Density functional theory (DFT) calculation and Raman scattering experiment have been applied to investigate an important essential fatty acid, α-linolenic acid (ALA). The DFT calculation was performed with geometry optimization and harmonic vibration using B3LYP functions with polarized 6-311+G(d,p) basis. The DFT calculated vibrational modes of ALA molecule are in excellent agreement with the Raman experimental results. A complete vibrational modes assignment is provided on the basis of potential energy distribution calculation. In addition, the DFT calculation and Raman experiment indicate that the relative intensity ratio of two characteristic modes at 1660 cm-1 and 1440 cm-1 is correlated with the number of C=C double bond in the acid chain, which may provide a simple and convenient method to differentiate ALA with other types of unsaturated fatty acids. Furthermore, the Mulliken atomic charge distribution and frontier molecular orbitals of ALA molecule were calculated.

Crystal structure and vibrational spectra of salts of 1H-pyrazole-1-carboxamidine and its protonation route

Crystal structures of five salts of 1H-pyrazole-1-carboxamidine, PyCA, with various inorganic acids were determined, (HPyCA)Cl, (HPyCA)Cl·H2O, (HPyCA)Br, (HPyCA)2(I)I3, and (HPyCA)HSO4. Theoretical calculations of the protonation route of PyCA showed that the cationic form present in the studied crystals is energetically privileged. Tautomeric equilibrium constants indicated two isomers as the most stable neutral forms. Calculations for two other tautomers failed resulting in pyrazole and carbodiimid tautomer of cyanamide. Such decomposition is important in a view of guanylation reaction. Hydrogen bonding patterns were studied by means of the graph-set approach. Similarities of the patterns in different crystal structures were demonstrated by the algebraic relations between descriptors of the patterns. The strength of hydrogen bonding network in the crystals was assessed analyzing vibrational spectra. The bands were assigned on the basis of theoretical calculations for the complex [(HPyCA)2Cl4]2– ion and potential energy distribution analysis. The strength of hydrogen bonds was set in the following ascending series (HPyCA)2(I)I3 (4) < (HPyCA)Br (3) < (HPyCA)Cl (1) < (HPyCA)Cl·H2O (2) < (HPyCA)HSO4 (5).

Molecular Docking, Topological Analysis and Vibrational Studies on N-(2-Bromoethyl) Succinimide: Antidepressant Agent

Abstract:: N-(2-Bromoethyl) succinimide (N2BES) is a compound with antidepressant pharmacological properties. N-(2-Bromoethyl) succinimide was analyzed for its structural, electronic, vibrational, topological, and biological properties. The molecular geometrical parameters such as bond lengths (Å), bond angles (º), and dihedral angles (º) of N2BES and harmonic vibrational frequencies were investigated using the density functional theory calculations with the B3LYP/6-311++G(d,p) level of theory. Experimental vibrational frequencies of N2BES were recorded in the region 4000–400 cm-1 (FT-IR) and 4000–100 cm-1 (FT-Raman) and compared with the theoretical frequencies were made on the basis of potential energy distribution (PED) analysis. Frontier molecular orbitals (FMOs), global reactivity descriptors, density of states (DOS) prop-erties, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, topological analysis of the reduced density gradient (RDG), localized orbital locator (LOL), bond critical points (BCP) for N2BES are investigated by theoret-ical calculations. The experimental UV-Vis measured within the 200-500 nm and calculated electronic transitions of ab-sorption wavelength (λ), excitation energies (E), oscillator strengths (f), and assignments in ethanol solvent. In addition, the molecular docking study of the title molecule predicts its binding orientation in the active site of the target serotonin 1A (5-HT1A) protein.

Structural, Vibrational and Electrochemical Analysis and Antibacterial Potential of Isomeric Chalcones Derived from Natural Acetophenone

Background: Chalcones are part of a family of small phenolic compounds that are being extensively studied for presenting a diversity of molecular structures and biological activities. In this paper, two chalcones, (E)-1-(2-hydroxy-3,4,6-trimethoxyphenyl)-3-(3-nitrophenyl)prop-2-en-1-one (1), (E)-1-(2-hydroxy-3,4,6-trimethoxyphenyl)-3-(4-nitrophenyl)prop-2-en-1-one (2), were synthesized by Claisen–Schmidt condensation. Methods: The molecular structures of these chalcones were determined by Nuclear Magnetic Resonance and characterized by infrared, Raman spectroscopy, and electrochemical analysis at room temperature. Vibrational wavenumbers were predicted using Functional Density Theory (DFT) calculations, and their normal modes were analyzed in terms of potential energy distribution (PED). Besides this, DFT calculations were performed to obtain the molecular orbitals and their quantum descriptors. The UV-Vis absorption spectrum of the synthesized chalcones was measured and compared with each other. In addition, analyses of antimicrobial activity and modulation of antibiotic resistance were carried out to assess the antibacterial potential of these chalcones. Results: The vibrational spectra of polycrystalline chalcones obtained by ATR-FTIR, FT-Raman and DFT calculations allowed a complete assignment of the vibrational modes, and revealed the quantum chemical parameters. Both chalcones did not show good responses when associated with the antibiotics Ciprofloxacin and Cephalexin against S. aureus 10 and E. coli 06 strains. However, a significant potentiating of the Gentamicin activity against S. aureus 10 and E. col 06 strains was observed for chalcone 2. On the other hand, when associated with Norfloxacin, an antagonistic effect was observed. The results found for EtBr suggest that, although the tested chalcones behave as efflux pump inhibitors, probably inhibiting other efflux pumps, they were not able to inhibit NorA. Thus, these synthetic chalcones are not recommended for use in association with Norfloxacin against strains of S. aureus 1199-B that overexpress the NorA gene. Conclusions: Spectroscopic data confirmed the structure of the chalcones, and chalcone 2 showed potential as an adjuvant in antibiotic therapy.