J. Kalyana Sundar

Structural, spectroscopic and nonlinear optical studies on a new efficient organic donor–acceptor crystal for second harmonic generation: l-Threoninium picrate

A new and efficient organic nonlinear optical (NLO) crystal from the amino acid family, viz., l-threoninium picrate (LTHP), has been grown by solvent evaporation technique from aqueous solution. The structure of LTHP was elucidated using single crystal X-ray diffraction data. The compound crystallized in the non-centrosymmetric space group P2(1) and the unit cell contains two l-threoninium cations and two picrate anions. The backbone conformation angles Psi(1) and Psi(2) are in cis and trans configurations for both the picrate and the threoninium residues. An intra-molecular hydrogen bond between the amine N atom and the nearby oxygen atom, viz., N1-H1B(...)O3 is observed, with a graph set motif R(1)(1)(5). The second harmonic generation (SHG) efficiency of this material was measured using Kurtz and Perry method and found to be about 43 times that of standard potassium dihydrogen phosphate (KDP) crystals. Fourier transform infrared (FTIR) and ultraviloet-visible-near infrared spectral studies were also carried out. The details are discussed.

Synthesis, growth, crystal structure and characterization of a new organic material: Glycine glutaric acid

Glycine glutaric acid, a new organic compound has been synthesized and good quality single crystals were grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal XRD. The presence of the functional groups was confirmed by using FT-IR spectroscopy. The optical transparency was studied by using UV-vis spectrophotometer and it was found that the crystal is having high optical transparency. The thermal stability of the crystal was studied by using thermo-gravimetric and differential thermal analyses and found that it is stable up to 150°C. The room temperature dielectric studies were also carried out over the wide frequency range: 10 mHz to 10 MHz.

Synthesis and characterization of a new strontium(II) coordination polymer based on a μ2-tridentate bridging zwitterionic glycine

The synthesis and characterization of a new Sr(II) coordination polymer (CP), [Sr(H2O)(H-gly)2Cl2] n (1) (H-gly = glycine), is described. Compound 1 crystallizes in the centrosymmetric orthorhombic space group Pcnb and its structure consists of a central Sr(II), a water molecule, a zwitterionic glycine, and a chloride. The central metal is nine coordinate, bonded to six oxygens from four different bridging H-gly ligands, two symmetry-related chlorides, and a terminal water molecule. The μ2-tridentate bridging zwitterionic glycine results in the formation of a 1-D CP with an Sr···Sr separation of 4.560 Å across the chain. The chloride, H-gly, and coordinated water are involved in five varieties of hydrogen bonding. A comparative study of the structural chemistry of several alkaline-earth glycine compounds is described.

l-Asparagine-l-tartaric acid (1/1).

In the title compound, C4H8N2O3·C4H6O6, the amino acid molecule exists as a zwitterion and the carboxylic acid in an un-ionized state. The tartaric acid molecules are linked into layers parallel to the ab plane by O—H⋯O hydrogen bonds. The amino acid molecules are also linked into layers parallel to the ab plane by N—H⋯O and C—H⋯O hydrogen bonds. The alternating tartaric acid and amino acid layers are linked into a three-dimensional framework by N—H⋯O and O—H⋯O hydrogen bonds.

Synthesis and structural characterization of a calcium coordination polymer based on a μ 3 -bridging tetradentate binding mode of glycine#

AbstractA new coordination polymer namely [[Ca6(H–gly)12(H2O)18]Cl12·6H2O]n (1) (H–gly = glycine) has been isolated from the calcium chloride–glycine–water system and structurally characterized. Each Ca(II) in 1 is eight-coordinated and is bonded to eight oxygen atoms three of which are from terminal water molecules and five oxygen atoms from four symmetry related zwitterionic glycine ligands. The H–gly ligands exhibit two different binding modes viz. a monodentate carboxylate ligation and a μ3-tetradentate bridging carboxylate binding mode, which results in the formation of a one-dimensional coordination polymer. In the infinite chain the Ca(II) atoms are organized in a zigzag fashion. A comparative study reveals a rich and diverse structural chemistry of calcium halide–glycine compounds. Graphical AbstractThe synthesis and structural characterization of a new coordination polymer namely [[Ca6(H–gly)12(H2O)18]Cl12·6H2O]n (1) (H-gly = glycine) isolated from the calcium chloride–glycine–water system is reported.

rac-2-Hy­droxy-2-(2-oxocyclo­pent­yl)-1H-indene-1,3(2H)-dione

In the title compound, C(14)H(12)O(4), the indene unit is essentially planar [r.m.s. deviation = 0.0309 (1) Å] and the cyclo-penta-none ring adopts a twist form. In the crystal, mol-ecules are joined via pairs of O-H⋯O hydrogen bonds into centrosymmetric dimers.

1,1'-[4-(2,4-Dichloro-phen-yl)-2,6-di-methyl-1,4-di-hydro-pyridine-3,5-di-yl]diethanone.

In the title compound, C17H17Cl2NO2, the central 1,4-dihydropyridine ring adopts a flattened-boat conformation. The ethanone substituents of the dihydropyridine ring at positions 3 and 5 have synperiplanar (cis) or antiperiplanar (trans) conformations with respect to the adjacent C=C bonds in the dihydropyridine ring. The 2,4-dichlorophenyl ring is almost planar [r.m.s. deviation = 0.0045 (1) Å] and almost perpendicular [89.27 (3)°] to the mean plane of the dihydropyridine ring. In the crystal, an N—H⋯O hydrogen bond links molecules into a zigzag chain along the ac diagonal. C—H⋯Cl contacts form centrosymmetric dimers and additional weak C—H⋯O contacts further consolidate the packing.