Irena Matulková

A new series of 3,5-diamino-1,2,4-triazolium(1+) inorganic salts and their potential in crystal engineering of novel NLO materials

Seven inorganic salts of 3,5-diamino-1,2,4-triazole (dat) with inorganic acids were prepared within our project focused on the crystal engineering of novel NLO materials and their X-ray structures were determined. Three triclinic compounds, dat(1+) selenate dihydrate, dat(1+) sulphate dihydrate and dat(1+) perchlorate, crystallize in the space group P. Three monoclinic structures of dat(1+) – i.e. nitrate, chloride hemihydrate and hydrogen phosphite crystallize in P21/c, P21/n and P21/c, respectively. Finally, the most promising structure of dat(1+) dihydrogen phosphate is orthorhombic (the space group Fdd2). The structure is formed by anionic layers parallel to the ac plane and the cationic chains parallel to the c axis. The FTIR and Raman spectra of the title compounds have been recorded and discussed. The assignment of the spectra is based on a quantum-chemical calculation and the factor group analysis. Quantitative powder measurements of the second harmonic generation of the only non-centrosymmetric dat(1+) dihydrogen phosphate at 1064 nm were performed and a relative efficiency equal to KDP (i.e. potassium dihydrogen phosphate) was observed. The consequent study of single crystal samples enabled the estimation of NLO tensor coefficients of this material.

Semi-organic salts of aniline with inorganic acids: prospective materials for the second harmonic generation

Three novel inorganic salts of aniline with sulfuric and selenic acids were prepared and characterized by X-ray structural analysis. Anilinium(1+) selenate, (C6H5NH3+)2SeO42−, and anilinium sulfate, (C6H5NH3+)2SO42−, crystallize in the monoclinic space groupC2. The crystal structures are based on hydrogen bonded layers of alternating anilinium cations and inorganic anions. Anilinium(1+) selenate dihydrate, (C6H5NH3+)2SeO42−·2H2O, crystallizes in the monoclinic space groupC2/c. The crystal structure is formed by a network of alternating anilinium cations, selenate anions and water molecules connected by a system of intermolecular hydrogen bonds. The FTIR and Raman spectra of all the compounds have been recorded and discussed as well as their crystal structures. According to the DSC curves and temperature dependence of lattice parameters, anilinium sulfate exhibits phase transitions at 217 and 182 K. The appropriate changes of vibrational spectra were also recorded during cooling of the sample especially in the N–H stretching and sulfate antisymmetric stretching (ν3SO42−) spectral regions. The quantitative measurements of the second harmonic generation at 1064 nm were performed using powdered samples of anilinium sulfate, anilinium chloride and anilinium selenate, and the relative efficiencies deff = 0.05dKDP, deff = 2.33dKDP and deff = 0.05dKDP (KDP; i.e.KH2PO4) have been observed, respectively.

Molecular crystals of 2-amino-1,3,4-thiadiazole with inorganic oxyacids – crystal engineering, phase transformations and NLO properties

Eight inorganic salts of 2-amino-1,3,4-thiadiazole (2-athd) with hydrochloric, perchloric, nitric, sulphuric, selenic, phosphorous and phosphoric acids were prepared, and their crystal structures were determined. Seven of the compounds crystallise in monoclinic space groups – i.e., 2-athd(1+) chloride monohydrate (P21/c), 2-athd(1+) selenate monohydrate (Pc), 2-athd(1+) dihydrogen phosphate (Cc), 2-athd(1+) phosphite (P21/a), 2-athd(1+) nitrate (P21/c), 2-athd(1+) 2-athd perchlorate (P21/n) and 2-athd(1+) perchlorate (P21/c) – and one crystallises in an orthorhombic space group – 2-athd(1+) hydrogen sulphate (P212121). The thermal behaviours of the materials were studied (DSC) down to liquid nitrogen temperature, and the properties of the perchlorate, hydrogen sulphate and selenate monohydrate crystals were discussed with respect to the results of high or low-temperature X-ray diffraction, IR and Raman spectroscopic studies. Quantitative measurements of the second harmonic generation of the powdered non-centrosymmetric samples at 1064 and 800 nm were performed and a relative efficiency compared to KDP is presented.

Lidocaine barbiturate: a promising material for second harmonic generation

Lidocaine barbiturate is a novel organic, mechanically and optically stable non-linear optical material, which shows effects higher than that of KDP. The engineered material, which belongs to the group of organic salts containing polarizable components, was characterized by means of X-ray diffraction, optical properties measurements and calculations.

4-Amino-1H-1,2,4-triazol-1-ium nitrate

The non-centrosymmetric crystal structure of the novel semi-organic title compound, C2H5N4 +·NO3 −, is based on alternating layers of 4-amino-1H-1,2,4-triazolinium cations (formed by parallel chains of cations mediated by weak C—H⋯N hydrogen bonds) and nitrate anions interconnected via linear and bifurcated N—H⋯O hydrogen bonds and weak C—H⋯O hydrogen bonds. N—H⋯N hydrogen bonds link the anions and cations.

Tris(2-amino-1,3-thia-zolium) hydrogen sulfate sulfate monohydrate.

The centrosymmetric crystal structure of the novel semi-organic compound, 3C3H5N2S+·HSO4 −·SO4 2−·H2O, is based on chains of alternating anions and water molecules (formed by O—H⋯O hydrogen bonds). The chains are interconnected with the 2-amino-1,3-thiazolium cations via strong N—H⋯O and weak C—H⋯O hydrogen-bonding interactions into a three-dimensional network.

The crystal structure and optical properties of a pharmaceutical co-crystal – the case of the melamine–barbital addition compound

The melamine barbital co-crystal is a product of crystal engineering of non-linear optical materials composed of pharmaceutically active ingredients. The resulting crystal phase shows a non-linear effect higher than that of KDP. The material was characterized by means of X-ray diffraction and optical property measurements and calculations.

Bis(2-phenyl­biguanidium) adipate tetra­hydrate

In the title salt, 2C8H12N5 +·C6H8O4 2−·4H2O, the anion is located on a centre of symmetry. The observed supramolecular network of the crystal structure is produced by ten different hydrogen bonds of the N—H⋯N, N—H⋯O and O—H⋯O types. One additional O—H group is not connected to an acceptor site.

2-Amino-1,3-thia­zolium dihydrogen phosphate

In the title compound, C3H5N2S+·H2PO4 −, the dihydrogen phosphate anions form infinite chains along [001] via short O—H⋯O hydrogen bonds. The 2-aminothiazolium cations interconnect these chains into a three-dimensional network by short linear or bifurcated N—H⋯O and weak C—H⋯O hydrogen bonds.

Novel organic NLO material bis(N-phenylbiguanidium(1+)) oxalate – A combined X-ray diffraction, DSC and vibrational spectroscopic study of its unique polymorphism

Three polymorphic modifications of bis(N-phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313K, belongs to the monoclinic space group Cc (a=6.2560(2)Å, b=18.6920(3)Å, c=18.2980(5)Å, β=96.249(1)°, V=2127.0(1)Å(3), Z=4, R=0.0314 for 4738 observed reflections). The centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298K and belongs to the monoclinic space group P21/n (a=6.1335(3)Å, b=11.7862(6)Å, c=14.5962(8)Å, β=95.728(2)°, V=1049.90(9)Å(3), Z=4, R=0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis(N-phenylbiguanidium(1+)) oxalate (III) (a=6.1083(2)Å, b=11.3178(5)Å, c=14.9947(5)Å, β=93.151(2)°, V=1035.05(8)Å(3), Z=4, R=0.0345 for 2367 observed reflections and a temperature of 110K), which also belongs to the monoclinic space group P21/n. The crystal structures of the three characterized phases are generally based on layers of isolated N-phenylbiguanidium(1+) cations separated by oxalate anions and interconnected with them by several types of N-H(...)O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90K up to a temperature near the melting point of each crystal. The bis(N-phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range.