R. Premkumar

Structural, spectroscopic and molecular docking studies on 2-amino-3-chloro-5-trifluoromethyl pyridine: A potential bioactive agent

The most stable, optimized structure of the 2-amino-3-chloro-5-trifluoromethyl pyridine (ACTP) molecule was predicted by the density functional theory calculations using the B3LYP method with cc-pVQZ basis set. Antitumor activity of the ACTP molecule was evaluated by molecular docking analysis. The structural parameters and vibrational wavenumbers were calculated for the optimized molecular structure. The experimental and theoretical vibrational wavenumbers were assigned and compared. Ultraviolet-visible spectrum was simulated and validated experimentally. The molecular electrostatic potential surface was simulated. Frontier molecular orbitals and related molecular properties were computed and further density of states spectrum was simulated. The natural bond orbital analysis was also performed to confirm the bioactivity of the ACTP molecule. The molecular docking analysis reveals the better inhibitory nature of the ACTP molecule against the colony-stimulating factor 1 (CSF1) gene which causes tenosynovial giant-cell tumor. Hence, the ACTP molecule can act as a potential inhibitor against tenosynovial giant-cell tumor.

Surface enhanced Raman spectroscopic studies on aspirin : An experimental and theoretical approach

Surface enhanced Raman scattering (SERS) studies on aspirin molecule adsorbed on silver nanoparticles (AgNPs) were investigated by experimental and density functional theory approach. The AgNPs were synthesized by the solution-combustion method and characterized by the X-ray diffraction and high resolution-transmission electron microscopy techniques. The averaged particle size of synthesized AgNPs was calculated as ∼55 nm. The normal Raman spectrum (nRs) and SERS spectrum of the aspirin were recorded. The molecular structure of the aspirin and aspirin adsorbed on silver cluster were optimized by the DFT/ B3PW91 method with LanL2DZ basis set. The vibrational frequencies were calculated and assigned on the basis of potential energy distribution calculation. The calculated nRs and SERS frequencies were correlated well with the observed frequencies. The flat-on orientation was predicted from the nRs and SERS spectra, when the aspirin adsorbed on the AgNPs. Hence, the present studies lead to the understanding ...

Surface Enhanced Raman Spectroscopy and Quantum Chemical Studies on Iminodiacetic Acid Single Crystals

Abstract Adsorption behaviour of iminodiacetic acid (IDA) on silver surface were investigated based on surface enhanced Raman spectroscopy (SERS) technique and density functional theory calculations. The single crystals of IDA were grown by slow evaporation method and characterized by powder X-ray diffraction (XRD), dynamic light scattering and scanning electron microscopy techniques. Silver nanoparticles (AgNPs) were prepared by solution combustion method using ananas comosus fruit extract as reducing agent. The AgNPs were characterized by powder XRD and high-resolution transmission electron microscopy techniques. Raman and SERS frequencies were analyzed on the basis of potential energy distribution calculation and compared with the experimental values. The structural parameters of IDA molecule was compared with the experimental values. In frontier molecular orbital analysis, the band gap value was significantly reduced for IDA after adsorption on the silver surface indicates the charge transfer associated with the process of adsorption. The redistribution of electrostatic potential and the reduction in band gap after adsorption on silver surface of IDA, reveals its utility in the design of electro active organic molecular devices. SERS spectral analysis reveals that the IDA adsorbed as a tilted orientation on the silver surface. Localization of electron density and the reduction in band gap after adsorption of silver nanoparticles pave the way for designing the electro active organic molecular devices.

Conformational, Vibrational Spectroscopic and Quantum Chemical Studies on 5-formyl-1h-pyrrole-2-carboxylic acid: A DFT Approach

The potential energy surface (PES) scan was performed for 5-formyl-1h-pyrrole-2-carboxylic acid (FHPC) molecule and the most stable optimized molecular structure was predicted using DFT/B3LYP method with 6-31G basis set. The theoretical vibrational frequencies were calculated for the optimized FHPC molecule using DFT/B3LYP method with cc-pVTZ basis set by Gaussian 09 Program package. The vibrational frequencies were assigned on the basis of potential energy distribution (PED) calculation using VEDA 4.0 program. The molecular reactivity, stability, intramolecular charge transfer studies and the calculation of ionization energy, electron affinity, global hardness, chemical potential, electrophilicity index and softness of the FHPC molecule were carried out using frontier molecular orbitals (FMOs) analysis. The bioactivity of the FHPC molecule was further confirmed using natural bond orbital (NBO) analysis.

Structural, vibrational spectroscopic and quantum chemical studies on indole-3-carboxaldehyde

The potential energy surface (PES) scan was performed for indole-3-carboxaldehyde (ICA) and the most stable optimized conformer was predicted using DFT/B3LYP method with 6-31G basis set. The vibrational frequencies of ICA were theoretically calculated by the DFT/B3LYP method with cc-pVTZ basis set using Gaussian 09 program. The vibrational spectra were experimentally recorded by Fourier transform-infrared (FT-IR) and Fourier transform-Raman spectrometer (FT-Raman). The computed vibrational frequencies were scaled by scaling factors to yield a good agreement with observed vibrational frequencies. The theoretically calculated and experimentally observed vibrational frequencies were assigned on the basis of potential energy distribution (PED) calculation using VEDA 4.0 program. The molecular interaction, stability and intramolecular charge transfer of ICA were studied using frontier molecular orbitals (FMOs) analysis and Mulliken atomic charge distribution shows the distribution of the atomic charges. The pr...

Conformational, vibrational spectroscopic and nonlinear optical activity studies on N,N-Di-Boc-2-amino pyridine : A DFT approach

The conformational analysis was carried out for N,N-Di-Boc-2-amino pyridine using potential energy surface (PES) scan and the most stable optimized conformer was predicted. The theoretical vibrational frequencies were calculated for the optimized geometry using DFT/B3LYP cc-pVTZ basis set by Gaussian 09 Program. The vibrational frequencies were assigned on the basis of potential energy distribution calculation using VEDA 4.0 program package. The Mulliken atomic charge values were calculated. In the Frontier molecular orbitals analysis, the molecular reactivity, kinetic stability, intermolecular charge transfer studies and the calculation of ionization energy, electron affinity, global hardness, chemical potential, electrophilicity index and softness of the molecule were carried out. The nonlinear optical (NLO) activity was examined and the first order hyperpolarizability value was computed, which was 2.27 times greater than the urea. The natural bond orbital analysis was also performed to confirm the NLO ...

Orientation of N-benzoyl glycine on silver nanoparticles: SERS and DFT studies

Surface enhanced Raman scattering (SERS) studies of N-benzoyl glycine (NBG) adsorbed on silver nanoparticles (AgNPs) was studied by experimental and density functional theory (DFT) approach. Single crystals of NBG were prepared using slow evaporation method. The AgNPs were prepared and characterized. The DFT/ B3PW91 method with LanL2DZ basis set was used to optimize the molecular structure of NBG and NBG adsorbed on silver cluster. The calculated and observed vibrational frequencies were assingned on the basis of potential energy distribution calculation. The reduced band gap value was obtained for NBG adsorbed on silver nanoparticles from the frontier molecular orbitals analysis. Natural bond orbital analysis was carried out to inspect the intra-molecular stabilization interactions, which are responsible for the bio activity and nonlinear optical property of the molecule. The spectral analysis was also evidenced that NBG would adsorb tilted orientation on the silver surface over the binding sites such as...