A study of the crystal structures, supra-molecular patterns and Hirshfeld surfaces of bromide salts of hypoxanthine and xanthine.

Two new crystalline salts, namely, hypoxanthinium bromide monohydrate, C5H5N4O+·Br-·H2O (I) and xanthinium bromide monohydrate, C5H5N4O2 +·Br-·H2O (II), were synthesized and characterized by single-crystal X-ray diffraction technique and Hirshfeld surface analysis. The hypoxanthinium and xanthinium cations in salts I and II are both in the oxo-N(9)-H tautomeric form. The crystal packing of the two salts is governed predominantly by N-H⋯O, N-H⋯Br, C-H⋯Br and O-H⋯Br inter-actions described by R 2 3(9) and R 2 2(8) synthons. The crystal packing is also consolidated by carbon-yl⋯π inter-actions between symmetry-related hypoxanthinium (HX+ ) cations in salt I and xanthinium cations (XA+ ) in salt II. The combination of all these inter-actions leads to the formation of wave- and staircase-like architectures in salts I and II, respectively. The largest contributions to the overall Hirshfeld surface are from Br⋯H/H⋯Br contacts (22.3% in I and 25.4% in II) .

Crystal structures and Hirshfeld surface analyses of hypoxanthine salts involving 5-sulfosalicylate and perchlorate anions.

Two salts of 1,9-di-hydro-purin-6-one (hypoxanthine), namely, 6-oxo-1,9-di-hydro-purin-7-ium 5-sulfosalicylate dihydrate, C5H5N4O+·C7H5O6S-·2H2O, (I), and 6-oxo-1,9-di-hydro-purin-7-ium perchlorate monohydrate, C5H5N4O+·ClO4 -·H2O, (II), have been synthesized and characterized using single-crystal X-ray diffraction and Hirshfeld analysis. In both salts, the hypoxanthine mol-ecule is protonated at the N7 position of the purine ring. In salt (I), the cation and anion are connected through N-H⋯O inter-actions. The protonated hypoxanthine cations of salt (I) form base pairs with another symmetry-related hypoxanthine cation through N-H⋯O hydrogen bonds with an R 2 2(8) ring motif, while in salt (II), the hypoxanthine cations are paired through a water mol-ecule via N-H⋯O and O-H⋯N hydrogen bonds with an R 3 3(11) ring motif. The packings within the crystal structures are stabilized by π-π stacking inter-actions in salt (I) and C-O⋯π inter-actions in salt (II). The combination of several inter-actions leads to the formation of supra-molecular sheets extending parallel to (010) in salts (I) and (II). Hirshfeld surface analysis and fingerprint plots reveal that O⋯H/H⋯O contacts play the major role in the crystal packing of each of the salts, with a 54.1% contribution in salt (I) and 62.3% in salt (II).

Synthesis, crystal structure determination and Hirshfeld surface analysis of three new salt forms of creatinine with hydrobromic acid, 3-aminobenzoic acid and 3,5-dinitrobenzoic acid.

Creatinine, a biologically important compound, is used to analyze kidney function and kidney diseases in the human body. The salt form of creatinine is used in the formation of drug materials like anti-HIV, antifungal, antiprotozoal, antiviral and antitumour compounds. Here we report the solid-state structures of three new crystalline salts, namely, creatininium (2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium) bromide, C4H8N3O+·Br-, (I), creatininium 3-aminobenzoate, C4H8N3O+·C7H6NO2-, (II), and creatininium 3,5-dinitrobenzoate, C4H8N3O+·C7H3N2O6-, (III). These salts have been synthesized and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. The structural chemistry of salts (I)-(III) and their crystal packing are discussed in detail. The primary interaction between the creatinine cation and the acid anion in the three salts is N-H...Br/O hydrogen bonds. In salt (I), the creatinine cation and bromide anion are connected through a pair of N-H...Br hydrogen bonds forming R42(8) and R42(12) ring motifs. In salts (II) and (III), the creatinine cation interacts with the corresponding anion via a pair of N-H...O hydrogen bonds. The crystal structure is further stabilized by C-H...O and O-H...O hydrogen bonds with the ring motifs R22(8), R21(7) and R21(6). Furthermore, the crystal structures are stabilized by π-π, C-H...π, C-O...π and N-O...π stacking interactions. The contributions made by each hydrogen bond in maintaining the crystal structure stability has been quantified by Hirshfeld surface analysis.

Structure determination and Hirshfeld surface analysis of new cocrystal and salt forms of 5-aminotetrazole with hydroxy- and nitro-substituted carboxylic acids.

Two new crystalline solids, namely, 5-aminotetrazole-3,5-dihydroxybenzoic acid-water (1/4/6), CH3N5·4C7H6O4·6H2O (I), and 5-aminotetrazolium 3,5-dinitrosalicylate, CH4N5+·C7H3N2O7- (II), have been synthesized and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. The crystal packing arrangements of I and II are governed by N-H...O and O-H...O hydrogen-bonding interactions. In cocrystal I, adjacent acid molecules are linked through O-H...O hydrogen bonds, forming a dimer with an R22(8) motif. In salt II, the tetrazolium cation and acid anion are linked through N-H...O hydrogen bonds to also form a dimer with an R22(8) motif. Further N-H...O and O-H...O hydrogen bonds help to stabilize the crystal packing, along with aromatic π-π stacking interactions in I and carbonyl...π interactions in II. The Hirshfeld surface analysis and fingerprint plots reveal that O...H/H...O interactions contribute 34.4% of the total interactions in the crystal packing of cocrystal I and 36.7% in salt II.

catena-Poly[[bis-(1H-indole-5-carboxyl-ato-κ2 O,O')zinc(II)]-µ-4,4'-azobi-pyridine-κ2 N 1:N 1'].

The asymmetric unit of the title coordination polymer [Zn(C9H6NO2)2(C10H8N4)] n , consists of one ZnII cation, one bidentate 1H-indole-5-carboxyl-ate (I5C) anion and half of a 4,4'-azobi-pyridine (Abpy) neutral ligand. In the coordination polyhedron, the ZnII ion adopts a distorted octa-hedral geometry. The coordination polymer is stabilized by a combination of N-H⋯O and C-H⋯π inter-actions, which leads to the formation of wave-like two-dimensional coordination polymeric layers.

4-(2,3-Di-chloro-phen-yl)piperazin-1-ium picrate.

The title compound, C6H2N3O7 -·C10H13Cl2N2 +, crystallizes with one 1-(2,3-di-chloro-phen-yl)piperazine (DP) cation and one picrate (PA) anion in the asymmetric unit. In the crystal structure, the DP cation and PA anion are inter-connected via several N-H⋯O and C-H⋯O hydrogen bonds. The DP cation and PA anion are further connected through C-Cl⋯π [3.8201 (4), 3.7785 (4) Å] and N-O⋯π [3.7814 (4) Å] inter-actions. The DP cations are further inter-connected via a weak inter-molecular Cl⋯Cl [3.2613 (4) Å] halogen-halogen inter-action. The combination of these supra-molecular inter-actions leads to a herringbone like supra-molecular architecture.

2-[(5-Chloro-pyridin-2-yl-imino)-meth-yl]phenol.

In the title compound, C12H9ClN2O, the dihedral angle between the aromatic rings is 1.78 (4)° and an intra-molecular O-H⋯N hydrogen bond closes an S(6) ring. In the crystal, C-H⋯O and C-H⋯N hydrogen bonds connect the mol-ecules into [001] chains.

Crystal structure of 2,4-di-amino-6-oxo-3,6-di-hydro-pyrimidin-1-ium p-toluene-sulfonate.

In the title salt, C4H7N4O(+)·C7H7O3S(-), the 2,6-di-amino-4-oxo-1,3-di-hydro-pyrimidin-1-ium cation inter-acts with the sulfonate group of the p-toluene-sulfonate anion via a pair of N-H⋯O hydrogen bonds, forming a hetero-synthon R 2 (2)(8) that mimics the role of a carboxyl-ate. The self-assembled cations form a homo-synthon R 2 (1)(6) motif which is further linked with the sulfonate anion via N-H⋯O hydrogen bonds to generate an R 3 (2)(10) ring motif. The three motifs are fused together and extended as supra-molecular ribbons along the b-axis direction. Adjacent ribbons are further linked via N-H⋯O hydrogen bonds to form an annulus, with an R 4 (4)(20) ring motif, resulting in a tunnel-like arrangement propagating along [010]. There are slipped parallel π-π stacking inter-actions [inter-centroid distance = 3.6539 (7) Å], between the tunnel-like polymer chains, forming slabs parallel to (100).

Hydrogen bonding patterns in salts of derivatives of aminopyrimidine and thiobarbituric acid.

Three salts, namely 2-amino-4,6-dimethylpyrimidin-1-ium thiobarbiturate trihydrate (I), 2-amino-4,6-dimethoxypyrimidin-1-ium thiobarbiturate dihydrate (II) and 2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidin-1-ium thiobarbiturate (III), were synthesized and characterized by IR and X-ray diffraction techniques. The primary interaction between the acid and base happens via N-H...O hydrogen bonds in (II) and (III), and via water-mediated N-H...OW and OW-HW...S in (I). The water molecules present in compound (I) form a (H2O)12 water cluster via water-water interactions. In all three compounds (I)-(III), thiobarbiturate anions form self-complementary pairs with a robust R2(2)(8) motif via a pair of N-H...O/N-H...S hydrogen bonds. They mimic the nucleobase base pairs by utilizing the same groups (thymine/uracil uses N3-H and C4=O8 groups during the formation of Watson-Crick and Hoogsteen base pairs with adenine). Compound (I) forms a water-mediated base pair through N-H...OW hydrogen bonds and forms an R4(2)(12) motif. The formation of N-H...S hydrogen bonds, water-mediated base pairs and water-water interactions in these crystal systems offers scope for these systems to be considered as a model in the study of hydration of nucleobases and water-mediated nucleobase base pairs in macromolecules.

1-[2-(Di-methyl-aza-nium-yl)eth-yl]-1H-1,2,3,4-tetra-zole-5-thiol-ate.

In the crystal structure of the title zwitterion, C5H11N5S, mol-ecules are linked via N-H⋯N hydrogen bonds, forming zigzag chains propagating along [010]. The chains are linked by C-H⋯S hydrogen bonds, forming two dimensional networks lying parallel to (001).

Supramolecular architecture of metal-organic frameworks involving dinuclear copper paddle-wheel complexes.

The two centrosymmetric dinuclear copper paddle-wheel complexes tetrakis(µ-4-hydroxybenzoato-κ(2)O:O')bis[aquacopper(II)] dimethylformamide disolvate dihydrate, [Cu2(C7H5O3)4(H2O)2]·2C3H7NO·2H2O, (I), and tetrakis(µ-4-methoxybenzoato-κ(2)O:O')bis[(dimethylformamide-κO)copper(II)], [Cu2(C8H7O3)4(C3H7NO)2], (II), crystallize with half of the dinuclear paddle-wheel cage unit in the asymmetric unit and, in addition, complex (I) has one dimethylformamide (DMF) and one water solvent molecule in the asymmetric unit. In both (I) and (II), two Cu(II) ions are bridged by four syn,syn-η(1):η(1):µ carboxylate groups, showing a paddle-wheel cage-type structure with a square-pyramidal coordination geometry. The equatorial positions of (I) and (II) are occupied by the carboxylate groups of 4-hydroxy- and 4-methoxybenzoate ligands, and the axial positions are occupied by aqua and DMF ligands, respectively. The three-dimensional supramolecular metal-organic framework of (I) consists of three different R2(2)(20) and an R4(4)(36) ring motif formed via O-H···O and OW-HW···O hydrogen bonds. Complex (II) simply packs as molecular species.

2-Amino-4,6-di-methyl-pyrimidine-sorbic acid (1/1).

In the crystal of the title compound, C6H9N3·C6H8O2, the 2-amino-4,6-di-methyl-pyrimidine and sorbic acid mol-ecules are linked through N-H⋯O and O-H⋯N hydrogen bonds, which generate a cyclic bimolecular heterosynthon with an R 2 (2)(8) graph-set motif. Further, two inversion-related pyrimidine mol-ecules are base-paired via a pair of N-H⋯N hydrogen bonds, forming a cyclic bimolecular homosynthon with a graph-set of R 2 (2)(8). A discrete hetero tetra-meric supra-molecular unit along the b axis is formed by the fusion of two heterosynthons and one homosynthon. An aromatic π-π inter-action [centroid-centroid distance = 3.7945 (16) Å] is observed between these tetra-meric units.

2-Amino-4,6-dimeth-oxy-pyrimidin-1-ium p-toluene-sulfonate.

In the title salt, C(6)H(10)N(3)O(2) (+)·C(7)H(7)O(3)S(-), the 2-amino-4,6-dimeth-oxy-pyrimidinium cation inter-acts with the sulfonate group of the p-toluene-sulfonate anion via a pair of N-H⋯O hydrogen bonds, forming a cyclic hydrogen-bonded R(2) (2)(8) motif, which in the crystal is linked by further intemolecular N-H⋯O hydrogen bonds, forming supra-molecular chains along the c axis. Furthermore, neighboring chains are inter-linked via weak C-H⋯O hydrogen bonds and C-H⋯π inter-actions, forming layers.

2,4-Diamino-6-methyl-1,3,5-triazin-1-ium tetra-fluoro-borate.

In the crystal structure of the title salt, C(4)H(8)N(5) (+)·BF(4) (-), centrosymmetrically related cations undergo base pairing via a pair of N-H⋯N hydrogen bonds, forming an R(2) (2)(8) ring motif. The cations and anions inter-act via N-H⋯F hydrogen bonds, generating supra-molecular layers parallel to ([Formula: see text]20), which are in turn linked into a three-dimensional network, forming rings of R(6) (6)(24) graph-set motif. The crystal structure is further stabilized by π-π stacking inter-actions [centroid-centroid distance = 3.3361 (12) Å].