Inorganic Salts of N-phenylbiguanidium(1+)-Novel Family with Promising Representatives for Nonlinear Optics

Seven inorganic salts containing N-phenylbiguanide as a prospective organic molecular carrier of nonlinear optical properties were prepared and studied within our research of novel hydrogen-bonded materials for nonlinear optics (NLO). All seven salts, namely N-phenylbiguanidium(1+) nitrate (C2/c), N-phenylbiguanidium(1+) perchlorate (P-1), N-phenylbiguanidium(1+) hydrogen carbonate (P21/c), bis(N-phenylbiguanidium(1+)) sulfate (C2), bis(N-phenylbiguanidium(1+)) hydrogen phosphate sesquihydrate (P-1), bis(N-phenylbiguanidium(1+)) phosphite (P21), and bis(N-phenylbiguanidium(1+)) phosphite dihydrate (P21/n), were characterised by X-ray diffraction (powder and single-crystal X-ray diffraction) and by vibrational spectroscopy (FTIR and Raman). Two salts with non-centrosymmetric crystal structures-bis(N-phenylbiguanidium(1+)) sulfate and bis(N-phenylbiguanidium(1+)) phosphite-were further studied to examine their linear and nonlinear optical properties using experimental and computational methods. As a highly SHG-efficient and phase-matchable material transparent down to 320 nm and thermally stable to 483 K, bis(N-phenylbiguanidium(1+)) sulfate is a promising novel candidate for NLO.

Crystallographic aspects of hydrated salts of 4,6-diaminopyrimidine with the first five dicarboxylic acids

The preparation, X-ray single-crystal structure determination and vibrational spectroscopic characterisation of five novel salts, i.e. bis(4,6-diaminopyrimidinium(1+)) oxalate tetrahydrate; 4,6-diaminopyrimidinium(1+) hydrogen malonate monohydrate; bis(4,6-diaminopyrimidinium(1+)) succinate octahydrate; bis(4,6-diaminopyrimidinium(1+)) glutarate dihydrate and bis(4,6-diaminopyrimidinium (1+)) adipate octahydrate, are presented. It is the first crystallographic study with the title cation. All the structures are centrosymmetric. The oxalate, succinate and adipate anions are situated about inversion centres in their respective structures. The dependence on the parity of the number of carbon atoms in the anions is apparent in the interplanar angles of the carboxylate or carboxylic groups. In all of the structures, there are intermolecular N–H···N, N–H···Oacid, N–H···Owater, Owater–H···Oacid and Owater–H···Owater hydrogen-bonds of moderate strength. The most common graph set motif, R 2 2(8), describes the arrangement of the involved carboxylic as well as of the primary- and secondary-amine groups. There is a growing complexity of arrangement of water molecules in the structures with longer anionic molecules. In 4,6-diaminopyrimidinium(1+) hydrogen malonate monohydrate, there is an intramolecular Oacid–H···Oacid bond, and the conformation of the hydrogen malonate ions with non-parallel carboxylic and carboxylate groups is not often observed. The structural parameters of the carboxylic or carboxylate groups in the dicarboxylic acids or their derivatives found in the Cambridge Structural Database (CSD) are compared with the title structures.

Bis(paracetamol) pyridine – a new elusive paracetamol solvate: from modeling the phase diagram to successful single-crystal growth and structure–property relations

In addition to the synthon approach, it is equally important to consider phase diagrams when searching for practical methods of crystallising multi-component crystals, either as single crystals or as powders.

Comparison of the hydrogen-bond patterns in 2-amino-1,3,4-thiadiazolium hydrogen oxalate, 2-amino-1,3,4-thiadiazole-succinic acid (1/2), 2-amino-1,3,4-thiadiazole-glutaric acid (1/1) and 2-amino-1,3,4-thiadiazole-adipic acid (1/1)

The X-ray single-crystal structure determinations of the chemically related compounds 2-amino-1,3,4-thiadiazolium hydrogen oxalate, C2H4N3S(+)·C2HO4(-), (I), 2-amino-1,3,4-thiadiazole-succinic acid (1/2), C2H3N3S·2C4H6O4, (II), 2-amino-1,3,4-thiadiazole-glutaric acid (1/1), C2H3N3S·C5H8O4, (III), and 2-amino-1,3,4-thiadiazole-adipic acid (1/1), C2H3N3S·C6H10O4, (IV), are reported and their hydrogen-bonding patterns are compared. The hydrogen bonds are of the types N-H···O or O-H···N and are of moderate strength. In some cases, weak C-H···O interactions are also present. Compound (II) differs from the others not only in the molar ratio of base and acid (1:2), but also in its hydrogen-bonding pattern, which is based on chain motifs. In (I), (III) and (IV), the most prominent feature is the presence of an R2(2)(8) graph-set motif formed by N-H···O and O-H···N hydrogen bonds, which are present in all structures except for (I), where only a pair of N-H···O hydrogen bonds is present, in agreement with the greater acidity of oxalic acid. There are nonbonding S···O interactions present in all four structures. The difference electron-density maps show a lack of electron density about the S atom along the S···O vector. In all four structures, the carboxylic acid H atoms are present in a rare configuration with a C-C-O-H torsion angle of ∼0°. In the structures of (II)-(IV), the C-C-O-H torsion angle of the second carboxylic acid group has the more common value of ∼|180|°. The dicarboxylic acid molecules are situated on crystallographic inversion centres in (II). The Raman and IR spectra of the title compounds are presented and analysed.