Subramanian Natarajan

Crystal growth and structure of L-methionine L-methioninium hydrogen maleate—a new NLO material

Abstract A new organic nonlinear optical (NLO) crystal from the amino acid family, viz., L-methionine L-methioninium hydrogen maleate (LMMM), has been grown by slow evaporation method from aqueous solution. Bulk crystals were grown using submerged seed solution method. The structure was elucidated using the single crystal x-ray diffraction data. The compound crystallized in the space group P21 and the unit cell contains a protonated L-methioninium cation and a zwitterionic methionine residue plus a maleate anion. The backbone conformation angles Ψ1 and Ψ2 are in cis and trans configurations for both the methionine and methioninium residues, respectively. Amino and carboxyl groups of the methioninium and methionine residues are connected through N–H…O hydrogen bonds leading to a ring R22(10) motif.

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.

L-Prolinium tartrate

In the title salt, C(5)H(10)NO(2)(+).C(4)H(5)O(6)(-), proline exists as a cation and the tartaric acid as a semi-tartrate anion. The semi-tartrate ions form hydrogen-bonded strings along the c axis. These strings are interconnected through the proline molecules, forming a layered network parallel to the bc plane. The proline molecules, however, do not directly interact among themselves, except for a weak C-H.O hydrogen bond.

Glycinium hydrogen fumarate glycine solvate monohydrate.

In the title compound, C2H6NO2 +·C4H3O4 −·C2H5NO2·H2O, the asymmetric unit contains two glycine residues, one protonated and one in the zwitterionic form, a hydrogen fumarate anion and a water molecule. Through N—H⋯O and O—H⋯O hydrogen bonds, molecules assemble in layers parallel to the (10) plane, one layer of hydrogen fumarate anions alternating with two layers of glycine molecules. In each glycine layer, hydrogen bonds generate an R 4 4(19) graph-set motif. Further hydrogen bonds involving the water molecule and the hydrogen fumarate anions result in the formation of a three-dimensional network.

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.n 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.

Crystal structure of L-histidinium 2-nitrobenzoate.

A new nonlinear optical organic compound, namely, L-histidinium 2-nitrobenzoate (abbreviated as LH2NB (I); ([C6H10N3O2]+ [C7H4NO4]−)), was synthesized. The molecular structure of LH2NB (I) was elucidated using single crystal X-ray diffraction technique. The second harmonic generation (SHG) efficiency of this compound is about two times that of the standard potassium dihydrogen phosphate crystals.

Synthesis and crystal structures of 5'-phenylspiro[indoline-3, 2'-pyrrolidin]-2-one derivatives

BackgroundThe spiro- indole-pyrrolidine ring system is a frequently encountered structural motif in many biologically important and pharmacologically relevant alkaloids. The derivatives of spirooxindole ring systems are used as antimicrobial, antitumour agents and as inhibitors of the human NKI receptor besides being found in a number of alkaloids like horsifiline, spirotryprostatin and (+) elacomine. The recently discovered small-molecule MDM2 inhibitor MI-219 and its analogues are in advanced preclinical development as cancer therapeutics.ResultsIn the crystal structures of the two organic compounds, 4-Nitro-3,5-diphenylspiro[indoline-3,2-pyrrolidin]-2-one and 3-(4-Methoxyphenyl)- 4-nitro -5-phenylspiro[indoline-3,2-pyrrolidin]-2-one, N-H···O hydrogen bonds make the R22 (8) ring motif. Further, the structures are stabilized by intermolecular hydrogen bonds.ConclusionThe crystal structures of 4-Nitro-3,5-diphenylspiro[indoline-3,2-pyrrolidin]-2-one and 3-(4-Methoxyphenyl)- 4-nitro -5-phenylspiro[indoline-3,2-pyrrolidin]-2-one have been investigated in detail. In both the compounds, the R22(8) motif is present. Due to the substitution of methoxyphenyl instead of phenyl ring, the entire configuration is inverted with respect to the 2-oxyindole ring.

Structural and spectral characterization of a new non-centrosymmetric organic thiosulfate

Aqueous reaction of ammonium thiosulfate with ethylenediamine (en) results in the formation of the title compound (enH(2))[S(2)O(3)] (1) (enH(2)=ethylenediammonium) in good yields. Compound 1 was characterized by analytical data, IR, Raman and NMR spectra, X-ray powder pattern and its crystal structure was determined. The structure of 1 which crystallizes in the non-centrosymmetric orthorhombic space group P2(1)2(1)2(1), consists of two crystallographically independent (enH(2))(2+) dications and two unique thiosulfate anions, which are interlinked by three varieties of H-bonding interactions, namely N-H⋯O, N-H⋯S, and C-H⋯O. (1)H and (13)C NMR spectra reveal the purity of 1 while its transparent nature can be evidenced from the UV-Vis-NIR spectral data. In compound 1 which exhibits SHG property, the infrared and Raman spectra confirm the presence of the organic dication and the thiosulfate anion.

Crystallization from Gels

Among the various crystallization techniques, crystallization in gels has found wide applications in the fields of biomineralization and macromolecular crystallization in addition to crystallizing materials having nonlinear optical, ferroelectric, ferromagnetic, and other properties. Furthermore, by using this method it is possible to grow single crystals with very high perfection that are difficult to grow by other techniques. The gel method of crystallization provides an ideal technique to study crystal deposition diseases, which could lead to better understanding of their etiology. This chapter focuses on crystallization in gels of compounds that are responsible for crystal deposition diseases. The introduction is followed by a description of the various gels used, the mechanism of gelling, and the fascinating phenomenon of Liesegang ring formation, along with various gel growth techniques. The importance and scope of study on crystal deposition diseases and the need for crystal growth experiments using gel media are stressed. The various crystal deposition diseases, viz. (1) urolithiasis, (2) gout or arthritis, (3) cholelithiasis and atherosclerosis, and (4) pancreatitis and details regarding the constituents of the crystal deposits responsible for the pathological mineralization are discussed. Brief accounts of the theories of the formation of urinary stones and gallstones and the role of trace elements in urinary stone formation are also given. The crystallization in gels of (1) the urinary stone constituents, viz. calcium oxalate, calcium phosphates, uric acid, cystine, etc., (2) the constituents of the gallstones, viz. cholesterol, calcium carbonate, etc., (3) the major constituent of the pancreatic calculi, viz., calcium carbonate, and (4) cholic acid, a steroidal hormone are presented. The effect of various organic and inorganic ions, trace elements, and extracts from cereals, herbs, and fruits on the crystallization of major urinary stone and gallstone constituents are described. In addition, tables of gel-grown organic and inorganic crystals are provided.