M. Vimalan

Synthesis of ZnO nanoparticles using leaf extract of Tectona grandis (L.) and their anti-bacterial, anti-arthritic, anti-oxidant and in vitro cytotoxicity activities

The novelty of this present work is the investigation of the anti-bacterial, anti-arthritic, anti-oxidant and in vitro cytotoxicity activities of green synthesized Zinc Oxide Nanoparticles (ZnO NPs) using leaf aqueous extract of Tectona grandis (L.). Zinc nitrate acts as the precursor and the leaf extract acts as the reducing agent. The synthesized ZnO NPs are characterized by powder X-ray diffraction (PXRD) analysis and the crystalline size is calculated by the Scherrer formula. FTIR analysis confirms the presence of various functional groups in the leaf extract as well as in the NPs. The UV absorption peak is observed at 360 nm and the calculated energy band gap is found to be 3.4 eV. Dynamic Light Scattering (DLS) analysis shows the stability and particle size of the synthesized ZnO NPs. The crystalline size, shape and surface morphology of the ZnO NPs are determined by using Field Emission Scanning Electron Microscopy (FE-SEM). Green synthesized ZnO NPs exhibited interesting antibacterial activity against Gram-positive and Gram-negative bacteria and exerted excellent DPPH (di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium) free radical scavenging activity. They also showed maximum inhibition of protein denaturation (90.46 ± 0.02) and proteinase inhibitory activity (87.68 ± 0.03) at a dose of 200 μg ml−1 respectively. The anticancer activity of ZnO NPs was also tested against normal and cancer osteoblast MC3t3-E1 cell lines and found a reduction in the size of cancer cells.

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.