Experimental and Computational Studies of Bis(thiourea) Lead Chloride: Semi-organic Material for NLO Applications

Silicon - Non liner optical single crystals of bis(thiourea) lead chloride (BTLC), belonging to the semi-organic material category, have been prepared by a slow solvent evaporation process. The...     

Benzimidazole: Dramatic luminescence turn-on by ZnO nanocrystals

A benzimidazole-based receptor 2-(4-fluorophenyl)-1-phenyl-1H-benzo[d]imidazole [FPPBI] has been designed, synthesized and characterized by ¹H NMR, ¹³C NMR, mass and single crystal XRD. Absorption, emission, lifetime and cyclic voltammetry have been made to deduce the interaction between FPPBI and ZnO nanocrystals. FPPBI act as a new host for ZnO nanocrystals that enhance its luminescence. The apparent binding constant has been obtained. Adsorption of the FPPBI on ZnO nanocrystals lowers the HOMO energy level of the FPPBI. The strong adsorption of the FPPBI on the surface of ZnO nanocrystals is likely due to the chemical affinity of the nitrogen atom of the FPPBI to the zinc ion on the surface of nanocrystals.     

Synthesis,NMR Spectral and DFT Studies of Styryl Imidazole Derivatives—Nano-SiO2 as an Efficient Catalyst

A series of novel styryl imidazole derivatives has been designed and synthesized using nano-SiO₂ as an efficient catalyst. Synthesized compounds have been characterized by ¹H and ¹³C-NMR spectral studies. The significant features of this nanocatalyst are high product yield, short reaction times and a vast range of substrates usage. Proton and ¹³C chemical shifts of the synthesized compounds were calculated. Single crystal XRD analysis has been carried out to confirm the structure of MDPI (1-(3-methoxyphenyl)-4, 5-dimethyl-2-phenyl-1H-imidazole) and it shows the imidazole ring is essentially planar and triclinic crystal. Optimization of compound MDPI was performed by DFT at B3LYP/6-31G (d, p) using Gaussian-03. Imidazole derivatives were used to construct highly sensitive fluorescent chemosensors for sensing of metal ions.

     

Nano-SiO<Subscript><Emphasis Type="Bold">2</Emphasis></Subscript>: An Efficient Catalyst for the Synthesis of Some new Benzimidazoles - NMR Spectral Characterization

Some benzimidazoles were designed and synthesized by a new route using nano-SiO₂ as a highly efficient catalyst. Synthesized compounds were characterized by ¹H and ¹³C-NMR spectral studies. The significant features of this nanocatalyst are high yield of products, short reaction times, green reaction media and a vast range of substrates usage. Proton and ¹³C chemical shift of the synthesized compounds were calculated. To further confirm the compound formation single crystal XRD analysis was made and discussed for 2-(1H-benzimidazol-2-yl) phenol (1). The crystal packing features four π– π stacking interactions involving the imidazole ring, fused benzene ring and attached benzene ring system [centroid–centroid distances = 3.6106 (17), 3.6108 (17), 3.6666 (17) and 3.6668 (17) Å]. Optimization of compound 1 was performed by DFT at B3LYP/6-31G (d, p) using Gaussian-03. All these XRD data are in good agreement with the theoretical values. However, from the theoretical values it is found that most of the optimized bond lengths, bond angles and dihedral angles are slightly higher than the XRD values.     

Physicochemical Analysis of Tetrakis (Thiourea) Palladium Chloride: A Prospective Non Linear Optical Crystal

The solubility test and nucleation kinetics studies of Tetrakis (thiourea) palladium chloride (TTPC) have been carried out and optical quality crystals of TTPC have been harvested by means of slow evaporation method. The single crystal X-ray diffraction studies revealed the orthorhombic structure and Pna2₁ space group of the crystals. To ascertain the stoichiometry and the purity of the crystals, elemental analysis has been performed. The etching studies of the crystal suggested the dimensional nucleation mechanism. Fourier Transform Infrared spectral studies have been employed in order to establish the metal—sulphur coordination prevailing in the crystal. The Ultra Violet transmittance study has been conducted to calculate the transmittance, band gap energy, Urbach’s energy, nature of electronic transitions, reflectance, refractive index, optical and electrical conductivities, extinction coefficient and electrical susceptibility. The mechanical stability of the TTPC crystals has been examined by Vicker’s hardness test in terms of hardness number, elastic stiffness constant, Meyer’s Index, minimum level of indentation load, load dependent constant, brittleness index and corrected hardness. Kurtz method has been adopted which showed the phase matching nature of TTPC and concluded that TTPC showed 1.15 times second harmonic generation efficiency as that of KDP. By using the dielectric and ac conductivity study, the activation energy values of the electrical process have been measured. Using theoretical approach, important solid state parameters such as valence electron plasma energy, Penn gap, Fermi energy and polarisability have been derived. The photoconductivity studies revealed the negative conductivity of the title crystal.     

Synthesis,Characterization and Recyclable Cerium Loaded CuO Nanocatalyst for the Synthesis of 1, 4- Disubstituted 1, 2, 3-Triazoles and Propargylamines

Silicon - Cerium loaded CuO nanoparticles (Ce-CuO NPs) were successfully synthesized by a precipitation-thermal decomposition method. The synthesized Ce-CuO NPs were used as a nanocatalyst for the...     

Synthesis,Characterization, Physico-Chemical and DFT Studies of Potential Organic NLO Materials: Experimental and Theoretical Combined Study

Silicon - 1-(2,4-difluorobenzyl)-2-(2,4-difluorophenyl)-6-methyl-1H-benzo[d]imidazole(1) and 1-(3-(tri fluoromethyl)benzyl)2-(4-(trifluoromethyl)phenyl)-6-methyl-1H-benzo[d]imidazole (2) were...     

Investigation of the Thermal and Dielectric Behavior of Epoxy Nano-Hybrids by using Silane Modified Nano-ZnO

The present work focuses on a comparative study of the thermal and electrical behavior of diglycidyl ethers of bisphenol-A (DGEBA) to uncover the suitability for its use in high performance applications. An epoxy nanohybrids coating was developed using aminosilane functionalized ZnO (1, 3, 5 and 7 wt%) as the dispersed phase and commercially available DGEBA as the matrix phase, with curing using triethylenetetramine (TETA). The structural features of these materials were ascertained by FTIR spectral studies, SEM and AFM analyses. The peak shift in all the samples at ～ 1032 cm^?1 explains the etheric linkage of ZnO-APTES core shell nanoparticles with the DGEBA virgin epoxy resin. The thermal behavior of the diglycidyl resins and their corresponding nano-hybrids was studied by TGA and DSC. The first decomposition stage of DGEBA neat epoxy resin starts at 325 °C and the second stage at 513.2 °C which varied in all epoxy nanocomposites. Further thermodynamic parameters are calculated using the Coats-Redfern method from TGA results to examine the thermal stability. The sample with 3% ZnO-APTES-DGEBA film exhibits the highest activation energy of 26.20 kj/mol. The dielectric permittivity, dielectric loss and AC conductivity variation with frequency, temperature and filler concentration were studied using an impedance analyzer. The variation in electrical behavior is more pronounced in 1 and 7% ZnO-APTES-DGEBA epoxy nanocomposites.     

Distribution of Heavy Metals in the Marine Sediments of Various Sites in Karaichalli Island,Tuticorin, Gulf of Mannar,India

The study of heavy metals in the sediments of coral islands is significant in understanding the distribution levels and the cause of anthropogenic impacts along the marine environment. A large number of heavy metals is discharged through domestic and industrial effluents along the coastal area of the southeast coast of India. In this work the sediments from Karaichalli island of Tuticorin were collected and the samples subjected to a total digestion technique and major and trace elements concentration estimated. To interpret and assess the contamination status for heavy metals in sediments, four metal pollution indices were assessed using a enrichment factor, a geo-accumulation index, contamination factor and pollution load index. The results were treated with SPSS 16.0 software for statistical analysis like Correlation matrix and Principal component analysis. The average metal accumulation levels in coral samples of the study area is in the following order: Fe > Mn > Zn > Cu > Ni > Pb > Cr > Cd > As > Co.