M. Dhandapani

Synthesis, structure, thermal and NLO characterization of 4-hydroxy tetramethylpiperazinium picrate crystals

AbstractGood quality single crystals of 4-hydroxy tetramethylpiperazinium picrate (TMPP) were grown by slow evaporation solution growth method at room temperature. The average dimensions of the grown crystals were 0.6 × 0.2 × 0.2 cm3. The solubility of the compound was estimated using methanol and acetone. The elemental analysis confirms the formation of the compound in the stoichiometric proportion. The UV-visible transmittance study indicates that the crystal possesses minimum transmittance at 370 nm and no absorption at 470–900 nm. The Bragg peaks obtained in the powder X-ray diffraction pattern confirm its crystallinity. The thermal behaviour of the crystal was investigated using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The structure of the compound was determined by using single crystal X-ray diffraction method. The compound was found to be crystallize in the monoclinic space group P2(1)/c (a = 6.9513(8)Å, b = 11.8016(14)Å, c = 22.018(2)Å, α = 90.00°, β = 92.575(2)°, γ = 90.00°). The thermal anomalies observed in the differential scanning calorimetry (DSC) heating and cooling cycles indicate the occurrence of first order phase transition. Fourier transform infrared (FTIR) and polarized Raman spectral analyses were used to confirm the presence of various functional groups in the compound. The nonlinear optical property (NLO) of the crystal was analysed by Kurtz-Perry powder technique and found that the compound has SHG efficiency 1.5 times greater that of potassium dihydrogen phosphate (KDP). Graphical AbstractA picric acid salt, 4-hydroxy tetramethylpiperazinium picrate was synthesized and crystallized. Thermal and spectral characterizations were carried out. The XRD structure determination indicated that the compound crystallized in monoclinic system with space group P2(1)/c. The SHG efficiency of the crystal was 1.5 times greater than that of KH2DPO4.

Ligand based pharmacophoric modelling and docking of bioactive pyrazolium 3-nitrophthalate (P3NP) on Bacillus subtilis, Aspergillus fumigatus and Aspergillus niger — Computational and Hirshfeld surface analysis

Biologically active Lewis acid-base compound, pyrazolium 3-nitro phthalate (P3NP) has been synthesized and crystallized by slow evaporation - solution method at 30°C. Spectral and single crystal X-Ray diffraction (XRD) were used to characterize the compound. The stability of the P3NP was confirmed by UV-Visible spectral analysis. P3NP crystallizes in monoclinic P21/C space group with cell parameters, a=13.009 (3) Å, b=12.584 (3) Å, c=7.529 (18) Å and β=93.052 (4)(o) with Z=4. Crystal packing was stabilized by N(+)H⋯O(-), OH⋯O and CH⋯O intermolecular hydrogen bonds. The nature of anion - cation interactions and crystal packing from various types of intermolecular contacts and their importance were explored using the Hirshfeld surface analysis. The structure was optimized by Density Functional Theory at B3LYP level with 6-311++G(d,p) basis set and the vibrational frequencies were theoretically calculated. Band gap between Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) and Electrostatic potential (ESP) were calculated. Antimicrobial activities of P3NP with targets were clinically tested and were found to exhibit antibacterial activity against gram positive and antifungal activity against pathogens with Minimum Inhibitory Concentration (MIC). Ligand based pharmacophore modelling was used to understand the potential of P3NP ligand to bind with selected target proteins. iGEM Dock was used to predict the modes of interactions of the ligand with target proteins of the microbes predicted from pharmacophore. PreADMET predicts no absorption of ligand in Human Intestinal Absorption (HIA).

Growth, spectral, dielectric and antimicrobial studies on 4-piperidinium carboxylamide picrate crystals

Single crystal of 4-piperidinium carboxylamide picrate was grown by slow evaporation solution growth technique at ambient temperature. The average dimensions of grown crystal were 0.7×0.3×0.2 cm(3). The solubility of the compound was analyzed using methanol and acetone. Optical property of the compound was ascertained by UV-visible absorption spectral study. The sharp and well defined Bragg peaks observed in the powder X-ray diffraction pattern confirm its crystallinity. The different kinds of protons and carbons in the compound were confirmed by (1)H and (13)C NMR spectral analyses. The presence of various functional groups in the compound was assigned through polarized Raman spectral study. The mechanical property of the crystal was measured by Vickers microhardness test and the compound was found to be soft material. The dielectric constant and dielectric loss of the crystal decrease with increase in frequency. The antibacterial and antifungal activities of the crystal were studied by disc diffusion method and found that the compound shows good inhibition efficiency against various bacteria and fungi species.

Thermal, Spectral, and SHG Studies of 4-Piperidinium Carboxylamide Picrate Crystals

4-piperidinium carboxylamide picrate crystals were synthesized by slow evaporation method from a methanol solution at room temperature. The stoichiometric ratio of the complex was confirmed by elemental analysis. The ultraviolet-visible transmittance study indicates that the crystal possesses minimum transmittance at 360 nm and no absorption between 480 nm and 900 nm. The thermal analyses were used to analyze the thermal stability of the complex. The thermal anomalies observed in the cooling and heating curves of the differential scanning calorimetry indicate the occurrence of a first-order phase transition. Single crystal X-ray diffraction study reveals that the complex crystallizes in monoclinic system with space group P21/c. The various absorption bands observed in Fourier transform infrared spectral analysis were reasonably assigned. The second harmonic generation efficiency of the material was found to be five times greater than that of potassium dihydrogen phosphate.