C. Surendra Dilip

Crystal growth, spectral, optical and thermal properties of semiorganic nonlinear optical material: Picolinic acid hydrochloride

The bulk single crystal of 2-picolinic acid hydrochloride (PHCL) (a semi-organic nonlinear optical material of dimensions 25×15×10 mm(3)) was successfully grown by slow solvent evaporation technique. The XRD results revealed the cell parameters and the centrosymmetric nature of the crystal structure. FT-IR spectral study identified the functional groups, nature of bonding and their bond strength. The UV-Vis-NIR studies recognized the optical transmittance window and the lower cut off wavelength of the PHCL crystal and thus it could be performed as a NLO material. (1)H NMR and (13)CNMR spectra were correlated with the XRD standard for the molecular structure reveals harmony of the materials. Thermal properties of the crystal were studied by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA); the derived kinetic parameter values support the intuitive association of picolinicacid and HCl leads to the spontaneous formation of PHCL with a first order reaction. The presence of a proton and a proton acceptor groups provide the necessary stability to induce charge asymmetry in the PHCL structure. The load dependent hardness values of the crystal were measured by microhardness testing.

A software program to investigate the nucleation kinetics of solution grown crystals using MATLAB platform

Abstract A software program has been developed on the MATLAB platform, which is useful for studying the nucleation kinetics of crystals grown from solutions. Nucleation parameters such as interfacial energy ( σ ) , metastable zone width ( Δ T max ) , volume free energy ( Δ G v ) , critical energy barrier for nucleation ( Δ G ∗ ) , radius of the critical nucleus ( r ∗ ) and nucleation rate ( J ) of the crystals are determined from classical nucleation theory. The Metastable Zone Width (MZW) of the crystals is explored by using the relation based on solubility and enthalpy of nucleation. A new polynomial equation has been generated by this software program, and the results are checked with the experimental data of crystal growth/formation. Nucleation temperature as a function of supersaturation ratio was successfully evaluated using MZW. The equation relating to the nucleation kinetics and MZW can easily be solved with the help of a newly designed software program in the MATLAB platform. In addition, a program has been developed that highlights changes in nucleation parameters when the supersaturation ratio is changed. A plot of temperature vs energy barrier, nucleation rate and interfacial energy is also drawn. Program summary Program title: Nucleation Catalogue identifier: AERG_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AERG_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 6305 No. of bytes in distributed program, including test data, etc.: 616560 Distribution format: tar.gz Programming language: MATLAB (MathWorks Inc.) version R2013a. Statistics Toolbox and Curve Fitting Toolbox required Computer: Any computer running MATLAB (MathWorks Inc.) Operating system: Tested on Windows XP, but generally it would work on any computer running MATLAB (MathWorks Inc.) RAM: 32 MB Classification: 8 Nature of problem: In crystal growth, the knowledge of nucleation thermodynamical parameters like interfacial energy, metastable zone width (supercooling temperature), volume free energy, critical energy barrier for nucleation, radius of critical nucleus and nucleation rates is essential for the growth of good quality bulk single crystals. In these parameters, metastable zone width determination is very useful for growth. Also some curve fitting tool is needed to obtain more information about nucleation kinetics. Solution method: In this program, an attempt has been made to calculate nucleation parameters theoretically to understand the role of these nucleation thermodynamical parameters for crystallization. A linear fit is done to calculate enthalpy of solution and polynomial fitting is used to derive the saturation concentration equation. Metastable zone width was calculated by the enthalpy–supersaturation relation. Supersaturation control is a decisive parameter for optimizing growth conditions during crystallization processes. The effects of metastable zone width and nucleation rate of crystals caused by changes in different supersaturation ratios were analyzed. Running time: Interactive and instantaneous.

Growth, structure, spectral and optical properties of semiorganic crystal: Pyridine-1-ium-2-carboxylatehydrogenbromide.

Pyridine-1-ium-2-carboxylatehydrogenbromide (PHBr) crystal was grown from aqueous solution by slow evaporation method. The calculated lattice parameters of single crystal X-ray diffraction have shown the triclinic crystal system with centrosymmetric space group of Pī. The interaction of functional groups and their importance in their application was identified by FTIR spectral analysis. The material is optically transparent and the grown crystal is having lower cut off wavelength as 294nm, thereby confirming the enhancement of non-linear optical (NLO) property and optical band gap of the PHBr have been determined as 2.49eV by UV-Vis-NIR studies. The (1)H NMR spectrum confirms the molecular structure and the presence of different kinds of protons.

Synthesis, Spectroscopic Characterisation, and Biopotential and DNA Cleavage Applications of Mixed Ligand 4-N,N-Dimethylaminopyridine Metal Complexes

The mixed ligand transition metal complexes of 4-N,N-dimethylaminopyridine (DP) and chloride as primary and secondary ligands with the general formula [M(DP)3Cl3]; M = Cr(III) and Fe(III); [M′(DP)4Cl2]M′ = Co(II), Ni(II), Cu(II), and Cd(II) were synthesized in a microwave oven. The complexes were characterized by FT-IR and UV, 1HNMR, 13CNMR spectra, TG/DTG, and various physicoanalytical techniques. From the magnetic moment measurements and the electronic spectral data, a distorted octahedral geometry was proposed for the complexes. The complexes express similar trend of thermal behaviour such that they lose water of hydration initially with the subsequent emission of organic and inorganic fragments and leave left the metal oxides as residue. The activation thermodynamic parameters, such as , , , and of the metal complexes, illustrate the spontaneous formation of the complexes. The antimicrobial studies against various pathogenic bacterial and fungal serums insist on that the enhanced potential of the complexes over their ligand and their biopotential properties increases with concentration. The DNA interaction of the synthesized complexes on CT-DNA was investigated by UV-Vis spectroscopy, viscosity, thermal denaturation, and electroanalytical experiments and their binding constants () were also calculated.