G. Venkatesa Prabhu

In Silico vibrational spectroscopic investigation on antioxidant active Mannich base 1-[anilino (phenyl) methyl] pyrrolidine-2,5-dione.

The antioxidant active Mannich base 1-[anilino (phenyl) methyl] pyrrolidine-2,5-dione (APMPD) have been synthesized and its FT-IR and FT-Raman vibrational spectra were recorded within the region of 4000cm(-1), 50cm(-1) respectively. The molecular geometric parameters of APMPD have been computed using HF and DFT model theories. The energies of APMPD are calculated for all the eight possible conformers using B3LYP method at 6-311++G(d,p) basis set. From the computational results, the M1 conformer was identified as the most stable conformer of APMPD. The stable conformer was compared with experimental crystal geometry, which again fortifies the results of conformer analysis. The fundamental vibrations of the molecule are assigned according to the characteristic region and the literature report. The predicted highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy gap provide vivid idea on charge transfer behavior of APMPD. The molecular electrostatic potential (MEP) and Mulliken charge analysis indicate the feasible electrophilic and nucleophilic reactive sites on APMPD. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at various temperatures are calculated in gas phase.

1-((4-methylpiperazin-1-yl)(phenyl)methyl)naphthalen-2-ol: A novel Mannich base organic NLO crystal for the analysis of electro-optic applications

Organic 2-naphthol derived 1-((4-methylpiperazin-1-yl)(phenyl)methyl)naphthalen-2-ol Mannich base non linear optical single crystal was synthesized and crystallized successfully to investigate the suitability of the material for electro-optic device applications. Acetonitrile was used as a solvent to develop optically good quality single crystal. Slow evaporation technique was employed at room temperature. Single crystal X-ray diffraction confirms the existence of non-centrosymmetric nature of the grown crystal. The nonlinear optical property was tested by Kurtz and Perry powder technique and the SHG efficiency of MPN was found to be 1.03 times than standard KDP. The PL spectrum of MPN shows blue light emission which confirms the material as potential candidate for the opto-electronic applications. The load dependent hardness was measured by Vickers’ microhardness test and various parameters such as yield strength, stiffness constant were calculated and reported. The dielectric constant and dielectric loss were measured as a function of frequency for different temperatures. The low dielectric constant and dielectric loss confirms the lesser defects and quality of the grown crystal. A fraction amount of activation energy obtained from ac conductivity measurement is an added advantage for electro-optic device fabrication. The dark current of MPN that leads the photo current shows the negative photo conducting nature of the material which may be due to the reduction of charge carriers.

First principles and DFT supported investigations on vibrational spectra and electronic structure of 2-((phenylamino)methyl)isoindoline-1,3-dione--an antioxidant active Mannich base.

The 2-((phenylamino)methyl)isoindoline-1,3-dione (PID) is a synthesized Mannich base which has significant antioxidant activity and biological importance. Quantum mechanical calculations on energy, geometry and vibrational wavenumber of PID were computed using ab initio HF and density functional theory (DFT/B3LYP) methods with 6-31+G/6-311++G(d,p) basis sets. Optimized geometrical parameters obtained by HF and DFT calculations were indicatively agreement with experimental crystal geometry. The experimental FT-Raman and FT-IR spectra of PID has been recorded and analyzed by comparing with simulated spectra. The (1)H and (13)C NMR spectra of title molecule records the chemical shift resulted from shielding and deshielding effects. Natural bond orbital (NBO) analysis has been carried out to calculate various intramolecular interactions that are accountable for the stabilization of this Mannich base. The predicted HOMO-LUMO gap offers interesting information on intramolecular charge transfer and reactivity of the molecular system. Molecular electrostatic potential (MEP) imprint visualize the reactive sites in PID, which is also supported by Mulliken, ESP, Hirshfeld and NBO charges. Thermodynamic properties of PID at various temperatures have been calculated at B3LYP/6-311++G(d,p) in gas phase and the correlations between standard entropies (S), internal energy (E or U) and standard heat capacity (C) with different temperatures.

Structural and Spectral Analysis of a Mannich Base: 3-(Morpholin-4-ylmethyl)-1,3-Benzothiazole-2-Thione

The crystal structure of 3-(morpholin-4-ylmethyl)-1,3-benzothiazole-2-thione, C12H14N2OS2, crystallizes in the monoclinic space group (P21/c). This benzothiazole derivative is a mannich base. Methylene group bridges the molecules of 2-mercapto benzothiazole and morpholine with an angle at the methylene bridge being 110.31(12)° [N–C–N]. The dihedral angle between the benzothiazole and morpholine planes is 70.37(5)°. The morpholine ring adopts a chair conformation. The molecular structure is stabilized by the weak C–H···S hydrogen bond in addition to the C–H···π and π···π interactions. Present study reports the conformation and hydrogen bonding interactions. Spectral analysis complement the structure analyzed.Graphical AbstractThe compound 3-(morpholin-4-ylmethyl)-1,3-benzothiazole-2-thione is a Mannich base. The crystal structure gives a picture of a methylene group bridging the molecules of 2-mercapto benzothiazole and morpholine.