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Two series of a total of ten cocrystals involving 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine with various carboxylic acids have been prepared and characterized by single‐crystal X‐ray diffraction. The pyrimidine unit used for the cocrystals offers two ring N atoms (positions N1 and N3) as proton‐accepting sites. Depending upon the site of protonation, two types of cations are possible [Rajam et al. (2017). Acta Cryst. C73, 862–868]. In a parallel arrangement, two series of cocrystals are possible depending upon the hydrogen bonding of the carboxyl group with position N1 or N3. In one series of cocrystals, i.e. 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–3‐bromothiophene‐2‐carboxylic acid (1/1), 1, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–5‐chlorothiophene‐2‐carboxylic acid (1/1), 2, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2,4‐dichlorobenzoic acid (1/1), 3, and 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2‐aminobenzoic acid (1/1), 4, the carboxyl hydroxy group (–OH) is hydrogen bonded to position N1 (O—H…N1) of the corresponding pyrimidine unit (single point supramolecular synthon). The inversion‐related stacked pyrimidines are doubly bridged by the carboxyl groups via N—H…O and O—H…N hydrogen bonds to form a large cage‐like tetrameric unit with an R42(20) graph‐set ring motif. These tetrameric units are further connected via base pairing through a pair of N—H…N hydrogen bonds, generating R22(8) motifs (supramolecular homosynthon). In the other series of cocrystals, i.e. 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–5‐methylthiophene‐2‐carboxylic acid (1/1), 5, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–benzoic acid (1/1), 6, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–2‐methylbenzoic acid (1/1), 7, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–3‐methylbenzoic acid (1/1), 8, 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–4‐methylbenzoic acid (1/1), 9, and 4‐amino‐5‐chloro‐2,6‐dimethylpyrimidine–4‐aminobenzoic acid (1/1), 10, the carboxyl group interacts with position N3 and the adjacent 4‐amino group of the corresponding pyrimidine ring via O—H…N and N—H…O hydrogen bonds to generate the robust R22(8) supramolecular heterosynthon. These heterosynthons are further connected by N—H…N hydrogen‐bond interactions in a linear fashion to form a chain‐like arrangement. In cocrystal 1, a Br…Br halogen bond is present, in cocrystals 2 and 3, Cl…Cl halogen bonds are present, and in cocrystals 5, 6 and 7, Cl…O halogen bonds are present. In all of the ten cocrystals, π–π stacking interactions are observed. [ABSTRACT FROM AUTHOR]

The crystals of two new salts, 2,6-diamino-4-chloropyrimidin-1-ium 5-chlorosalicylate, C4H6ClN4 +.C7H4ClO3 -, (I), and bis(2,6-diamino-4-chloropyrimidin-1- ium) naphthalene-1,5-di-sulfonate, 2C4H6ClN4 +.C10H6O6S2 2-, (II), have been synthesized and characterized by single-crystal X-ray diffraction. In both compounds, the N atom of the pyrimidine group in between the amino substituents is protonated and the pyrimidinium cation forms a pair of N-- H. . .O hydrogen bonds with the carboxylate/sulfonate ion, leading to a robust R2 2(8) motif (supramolecular heterosynthon). In compound (I), a selfcomplementary base pairing involving the other pyrimidinium ring nitrogen atom and one of the amino groups via a pair of N--H. . .N hydrogen bonds [R2 ²(8) homosynthon] is also present. In compound (II), the crystallographic inversion centre coincides with the inversion centre of the naphthalene-1,5- disulfonate ion and all the sulfonate O atoms are hydrogen-bond acceptors, generating fused-ring motifs and a quadruple DDAA array. A halogen-bond (Cl. . .Cl) interaction is present in (I) with a distance and angle of 3.3505 (12) Å and 151.37 (10)°, respectively. In addition, a C--Cl. . .π interaction and a π-π interaction in (I) and a π-π interaction in (II) further stabilize these crystal structures. [ABSTRACT FROM AUTHOR]

The design of a pharmaceutical cocrystal is based on the identification of specific hydrogen-bond donor and acceptor groups in active pharmaceutical ingredients (APIs) in order to choose a `complementary interacting' molecule that can act as an efficient coformer. 5-Fluorouracil (5FU) is a pyrimidine derivative with two N-H donors and C=O acceptors and shows a diversity of hydrogen-bonding motifs. Two 1:1 cocrystals of 5-fluorouracil (5FU), namely 5-fluorouracil-4-methylbenzoic acid (5FU-MBA), C4H3FN2O2·C8H8O2, (I), and 5-fluorouracil-3-nitrobenzoic acid (5FU-NBA), C4H3FN2O2·C7H5NO4, (II), have been prepared and characterized by single-crystal X-ray diffraction. In (I), the MBA molecules form carboxylic acid dimers [ R22(8) homosynthon]. Similarly, the 5FU molecules form two types of base pair via a pair of N-H...O hydrogen bonds [ R22(8) homosynthon]. In (II), 5FU interacts with the carboxylic acid group of NBA via N-H...O and O-H...O hydrogen bonds, generating an R22(8) ring motif (heterosynthon). Furthermore, the 5FU molecules form base pairs [ R22(8) homosynthon] via N-H...O hydrogen bonds. Both of the crystal structures are stabilized by C-H...F interactions. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title co-crystal, C12H9N5O·C7H6O3, contains one molecule of N6-benzoyladenine (BA) and one molecule of 4-hydroxybenzoic acid (HBA). The N6-benzoyladenine (BA) has an N(7)--H tautomeric form with nonprotonated N-1 and N-3 atoms. This tautomeric form is stabilized by a typical intramolecular N--H⋯O hydrogen bond between the carbonyl (C＝O) group and the N(7)--H hydrogen on the Hoogsteen face of the purine ring, forming a graph-set S(7) ring motif. The primary robust R²2(8) ring motif is formed in the Watson-Crick face via N--H⋯O and O--H⋯N hydrogen bonds (involving N1, N6--H and the carboxyl group of HBA).Weak interactions, such as, C--H⋯π and π-π are also observed in this crystal structure. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, 5-fluorocytosinium picrate, C4H5FN3O+·C6H2N3O7-, one N heteroatom of the 5-fluorocytosine (5FC) ring is protonated. The 5FC ring forms a dihedral angle of 19.97 (11)° with the ring of the picrate (PA-) anion. In the crystal, the 5FC+ cation interacts with the PA- anion through three-centre N--H⋯O hydrogen bonds, forming two conjoined rings having R2¹(6) and R1²(6) motifs, and is extended by N--H⋯O hydrogen bonds and C--H⋯O interactions into a two-dimensional sheet structure lying parallel to (001). Also present in the crystal structure are weak C--F⋯π interactions. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, 2C5H3ClO2S·C10H8N2, is comprised of a molecule of 3-chlorothiophene-2-carboxylic acid (3TPC) and half of a molecule of 4,4′-bipyridine (BPY). A distinctive O--H′N-based synthon is present. Cl′Cl and π-π stacking interactions further stabilize the crystal structure, forming a two-dimensional network parallel to the bc plane. [ABSTRACT FROM AUTHOR]

In the title salt, C6H9ClN3+·C6H3O4S-, the cations and anions are linked via O-H⋯O and N-H⋯O hydrogen bonds, forming R66(37) ring motifs that are inter?connected with each other, producing sheets. Separate parallel inversion-related sheets are linked through N-H⋯N and [pi]-[pi] stacking inter?actions [centroid-centroid distance = 3.5414 (13) Å], forming double layers parallel to (101). Weak C-H⋯O and C-H⋯S hydrogen bonds, as well as C-H⋯π inter?actions, connect the double layers into a three-dimensional network. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title co-crystal, C12H9N5O0.5C6H10O4, consists of one molecule of N6-benzoyladenine (BA) and one half-molecule of adipic acid (AA), the other half being generated by inversion symmetry. The dihedral angle between the adenine and phenyl ring planes is 26.71 (7)°. The N6-benzoyladenine molecule crystallizes in the N(7)--H tautomeric form with three non-pro tonated N atoms. This tautomeric form is stabilized by intramolecular N--H⋯O hydrogen bonding between the carbonyl (CO) group and the N(7)--H hydrogen atom on the Hoogsteen face of the purine ring, forming an S(7) ring motif. The two carboxyl groups of adipic acid interact with the Watson-Crick face of the BA molecules through O--H⋯N and N--H⋯O hydrogen bonds, generating an R2²(8) ring motif. The latter units are linked by N--H⋯N hydrogen bonds, forming layers parallel to (105. A weak C--H⋯O hydrogen bond is also present, linking adipic acid molecules in neighbouring layers, enclosing R²2(10) ring motifs and forming a three-dimensional structure. C=O⋯π and C--H⋯π interactions are also present in the structure. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, 4C4H4FN3O•C3H6N6, comprises of two independent 5-fluoro-cytosine (5FC) molecules (A and B) and one half-molecule of melamine (M). The other half of the melamine molecule is generated by a twofold axis. 5FC molecules A and B are linked through two different homosynthons [R2² (8) ring motif]; one is formed via a pair of N--H⋯O hydrogen bonds and the second via a pair of N--H⋯N hydrogen bonds. In addition to this pairing, the O atoms of 5FC molecules A and B inter-act with the N2 amino group on both sides of the melamine molecule, forming a DDAA array of quadruple hydrogen bonds and generating a supramolecular pattern. The 5FC (molecules A and B) and two melamine molecules interact via N--H⋯O, N--H⋯N and N--H⋯O, N--H⋯N, C--H⋯F hydrogen bonds forming R66(24) and R44(15) ring motifs. The crystal structure is further strengthened by C--H⋯F, C--F⋯π and π--π stacking interactions. [ABSTRACT FROM AUTHOR]

In the title molecular salt, C12H10N5O+·NO3-, the adenine unit has an N9-protonated N(7)--H tautomeric form with non-protonated N¹ and N³ atoms. The dihedral angle between the adenine ring system and the phenyl ring is 51.10(10)°. The typical intra­molecular N7--H···O hydrogen bond with an S(7) graph-set motif is also present. The benzoyl­adeninium cations also form base pairs through N--H···O and C--H···N hydrogen bonds involving the Watson-Crick face of the adenine ring and the C and O atoms of the benzoyl ring of an adjacent cation, forming a supra­molecular ribbon with R2²(9) rings. Benzoyl­adeninum cations are also bridged by one of the oxygen atoms of the nitrate anion, which acts as a double acceptor, forming a pair of N--HH···O hydrogen bonds to generate a second ribbon motif. These ribbons together with p-p stacking inter­actions between the phenyl ring and the five- and six-membered adenine rings of adjacent mol­ecules generate a three-dimensional supra­molecular architecture. [ABSTRACT FROM AUTHOR]

Background The usage of polynuclear metal clusters as secondary building units (SBU's) in designing of metal organic frameworks (MOF's) is a field of current interest. These metal clusters have attracted a great deal of attention not only due to their interesting structural topologies but also due to promising physical and chemical properties. In this regard various d,f block (transition and lanthanide) metal clusters have been widely investigated so far. Less attention is paid to construction of heavy p-block Pb(II) clusters. Results Two mixed ligand Pb(II) clusters have been synthesized with bipy(2,2'-Bipyridine), phen(1,10-Phenanthroline), quin (8-Hydroxy quinolinate) and 5-tpc (5-chloro thiophene 2- carboxylate). They have been characterized by elemental analysis, IR, TGA and X-ray crystallography. X-ray diffraction analysis reveals that the complexes [Pb4(quin)4(bipy)2(5- tpc)4] (1) and [Pb4(quin) 4(phen) 2(5-tpc)4] (2) are tetranuclear. The complexes show a slight variation in unit cell parameters, due to the replacement of bipy and the phen ligands. Both complexes contain two types of Pb(II) ions which differ in the coordination geometry around the Pb(II) ion. Conclusions In both complexes the four lead ions Pb1,Pb2, Pb1i and Pb2i lie on the same plane bridged by the 5-tpc anions. Pb1 and Pb2 of both complexes contain a 5-tpc and quin coordinated in a bidentate chelating bridging fashion. In addition the Pb2 and Pb2i ions alone contain a bipy and phen in a bidentate chelating fashion in (1) and (2) respectively. An additional notable feature in both of these complexes are the bridging ability of the quin oxygen which forms a network of coordination bonds in between the four Pb(II) ions. In both complexes the individual units are self-assembled by C-H---Cl/C-H---S hydrogen bonding interactions to generate 2-D aggregates. [ABSTRACT FROM AUTHOR]

The two centrosymmetric dinuclear copper paddle-wheel complexes tetrakis(μ-4-hydroxybenzoato-κ2 O: O′)bis[aquacopper(II)] dimethylformamide disolvate dihydrate, [Cu2(C7H5O3)4(H2O)2]·2C3H7NO·2H2O, (I), and tetrakis(μ-4-methoxybenzoato-κ2 O: O′)bis[(dimethylformamide-κ O)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 CuII ions are bridged by four syn, syn-η1:η1: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 R22(20) and an R44(36) ring motif formed via O-H...O and O W-H W...O hydrogen bonds. Complex (II) simply packs as molecular species. [ABSTRACT FROM AUTHOR]

Background: Lead is a heavy toxic metal element in biological systems and is one of the major pollutants as a result of its widespread use in industries. In spite of its negative roles the coordination chemistry of Pb(II) complexes is a matter of interest. The N,N'-bidentate aromatic bases such as BPY,4-BPY and PHEN (BPY = 2,2'bipyridine, 4-BPY = 4,4'-dimethyl-2,2'-bipyridine, PHEN = 1,10-Phenanthroline) are widely used to build supramolecular architectures because of their excellent coordinating ability and large conjugated system that can easily form π-π interactions among their aromatic moieties. A series of novel Pb(II) complexes in concert with 5-CTPC, 5-BTPC (5-CTPC = 5-chlorothiophen-2-carboxylate, 5-BTPC = 5-bromothiophen-2-carboxylate) and corresponding bidentate chelating N.N' ligands have been synthesized and characterized. Results: Five new Pb (II) complexes [Pb(BPY)(5-CTPC)2] (1), [Pb(4-BPY)(5-CTPC)2] (2), [Pb2(PHEN)2(5-CTPC)4] (3), [Pb(4-BPY)(5-BTPC)2] (4) and [Pb2(PHEN)2(5-BTPC)2(ACE)2] (5) have been synthesized. Even though in all these complexes the molar ratio of Pb, carboxylate, N,N-chelating ligand are the same (1:2:1), there is a significant structural diversity. These complexes have been characterised and investigated by elemental analysis, IR, 1H-NMR,13C-NMR, TGA, and photoluminescence studies. Single crystal X-ray diffraction studies reveal that complexes (1, 2) and (4) are mononuclear while (3 and 5) are dinuclear in nature which may result from the chelating nature of the ligands, various coordination modes of the carboxylates, and the coordination geometry of the Pb(II) ions. Conclusions: The observation of structures 2,4 and 3,5 show the structural changes made just chloro/bromo substituent of the thiophene ring. A detailed packing analysis has been undertaken to delineate the role of valuable non covalent interactions like X...π, H...X, (X = Cl/Br). A quadruple hydrogen bond linking the monomeric units and generating a supramolecular architecture is observed in (1). The metal bite unit comprised of PbN2C2 (i.e. Pb-N-C-C-N-Pb) is the repeating unit in all the five complexes and they have almost same geometrical parameters. This metal bite has been identified as the self assembly unit in complexes. [ABSTRACT FROM AUTHOR]

The article describes the crystal structures of the compounds hemi(4,4'-bipyridinium) tris(5-chiorothiophene-2-carboxylato)dioxidouranate(VI) monohydrate and hemi[4,4'-(ethane-l,2-diyl)dipyridin-ium] tris(5-chlorothiophene-2-carboxylato)dioxidouranate(VI) monohydrate. The metal centres are connected by classical O--H-.O and N--H.O hydrogen bonds involving the coordinated ligands, the diprotonated organic linker cation and water molecules. The crystal structures are further supported by weak C--H.O and π-π stacking interactions.

The article presents a paper about hydrogen-bonded supramolecular motifs in 2-amino-4,6-dimethoxypyrimidinium picrate and pyrimethaminium picrate dimethyl sulfoxide solvate. It mentions the use of picric acid as an acidic ligand to form salts with polar biomolecules through specific electrostatic or hydrogen-bonding interactions. According to one study, hydrogen bonding plays an important role in molecular recognition and crystal engineering research.

The article discusses the crystal structure of the metal-organic compound, Triaqua(µ-7-iodo-8-oxidoquinoline-5-sulfonato-k2N,O8)dioxidouranium(VI) dihydrate. It mentions that the compound's asymmetric unit has two uncoordinated water molecules, among others. The crystal structures of the copper complexes of the 8-hydroxy-7-iodoquinoline-5-sulfonic acid (HQS) are also examined.

In the title compound, C10H9N2+·C9H5INO4S-·2H2O, the 4,4'bipyridine molecule is protonated at one of the pyridine N atoms. These moieties self-assemble into a supramolecular chain along the a axis through N-H···N hydrogen bonds. The quinolinol OH group acts as a donor with respect to a sulfonate O atom [O-H···O(sulfonate)] and acts as an acceptor with respect to a C-H group of ferron [C-H···O(hydroxy)], forming a supramolecular chain along the b axis. These two types of supramolecular chains (one type made up of bipyridine motifs and the other made up of sulfoxine motifs) interact via π-π stacking, generating a three-dimensional framework. These chains are further crosslinked by C-H···O hydrogen bonds and O-H···O hydrogen bonds involving water molecules. [ABSTRACT FROM AUTHOR]

Investigates the conformation and hydrogen-bonding patterns of N[sup 6]-furfuryladenine hydrochloride. Adenine moiety existing as the N3-protonated N7-H tautomer; Orientation of the N6 substituent distal to the imidazole ring of the adenine base; Dihedral angle between the adenine plane and the furfuryl ring plane.

In the crystal structures of the title compounds, C6H10N3O2+·C7H5O3−·H2O, (I), C6H10N3O2+·C7H4NO4−·H2O, (II), and C6H10N3O2+·C4H5O6−·C6H9N3O2, (III), the 2-amino-4,6-di­meth­oxy­pyrimidinium cation [abbreviated as (MeO)2-Hampy+] inter­acts with the carboxyl­ate group of the corresponding anion through a pair of nearly parallel N—H⋯O hydrogen bonds to form R22(8) ring motifs. In (I), the (MeO)2-Hampy+ cation is centrosymmetrically paired through a pair of N—H⋯N hydrogen bonds involving the 2-amino group and a ring N atom forming an R22(8) motif. In (II), inversion-related R22(8) motifs (amino–pyrimidine–carboxyl­ate motifs) are further bridged by N—H⋯O hydrogen bonds on either side forming a DDAA array of quadruple hydrogen bonds. This array is extended further on either side by Owater—H⋯Ometh­oxy hydrogen bonds, resulting in an array of six hydrogen bonds ( ADDAAD). The water mol­ecule plays a pivotal role, and five hydrogen-bonded fused rings are formed around the water mol­ecule. In (III), the carb­oxy group of the tartrate anion inter­acts with the ring N atom and 2-amino group of the neutral (MeO)2-ampy mol­ecule through N—H⋯O and O—H⋯N hydrogen bonds. There is also an intra­molecular O—H⋯O hydrogen bond in the tartrate anion. In all three crystal structures, C—H⋯O hydrogen bonds are observed. [ABSTRACT FROM AUTHOR]

In the crystal structure of the title compound, C6H10N3+·C7H5O3-, the asymmetric unit contains four crystallographically independent 2-amino-4,6-dimethylpyrimidinium and salicylate ions (Z = 8). In each of these, one of the pyrimidine N atoms is protonated, and the carboxylate group of the salicylate ion interacts with the pyrimidine group through a pair of N—H…O hydrogen bonds, forming an R2²(8) motif. The pyrimidine cations also form base pairs via a pair of N—H…N hydrogen bonds (involving the amino group and the unprotonated ring N atom), forming another R2²(8) motif. Three such R2²(8) motifs, fused together, constitute a closed cyclic aggregate, and the linking of these aggregates, arranged in consecutive layers, can be analysed in terms of off-face stacking interactions. [ABSTRACT FROM AUTHOR]

In the title compounds, namely 2,4-diamino-5-[(3,4,5-trimethoxy­phenyl)methyl]­pyrimidin-1-ium pyridine-2-carboxyl­ate, C14H19N4O3+·C6H4NO2−, (I), and 2-amino-4,6-dimethyl­pyrimidin-1-ium pyridine-2-carboxyl­ate hemihydrate, C6H10N3+·C6H4NO2−·0.5H2O, (II), the trimethoprim and 2-amino-4,6-dimethyl­pyrimidin-1-ium cations are protonated at one of the pyrimidine N atoms. In (I), bifurcated hydrogen bonds are observed between a picolinate O atom, the protonated N atom and the 2-amino group; the graph-set designator is R21(6). The pyrimidine moieties of the trimethoprim cations are centrosymmetrically paired through a pair of N—H⋯N hydrogen bonds. In addition to the base pairing, one of the picolinate O atoms bridges the 2- and 4-amino groups on either side of the paired bases, resulting in a complementary DADA array. In (II), the carboxyl­ate group of the picolinate anion binds with the protonated pyrimidine N atom and the 2-amino group of the pyrimidine moiety through a pair of N—H⋯O hydrogen bonds, leading to the common ring motif R22(8). The water mol­ecule, which resides on a twofold rotation axis, bridges the carboxyl­ate group of the picolinate anion via O—H⋯O hydrogen bonds. [ABSTRACT FROM AUTHOR]

The title compound, 2,4-diamino-5-(4-chloro­phen­yl)-6-ethyl­pyrimidine-1,3-diium dinitrate, C12H15ClN42+·2NO3−, contains two crystallographically independent pyrimethamine (PMN) mol­ecules, which differ in the relative orientations of the pyrimidine and benzene rings and of the eth­yl substitutents. In both pyrimethamine mol­ecules, all the pyrimidine N atoms are protonated, unlike most related compounds, in which only one pyrimidine N atom is protonated. The two pyrimethamine moieties are bridged by a variety of N—H⋯O(nitrate) inter­actions, including some three-centre hydrogen bonds. [ABSTRACT FROM AUTHOR]

In the title mol-ecule, C10H10O4, the carb-oxy-lic acid group is twisted by 11.37 (15)° from the plane of the benzene ring and the acet-oxy group is twisted from this plane by 86.60 (17)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with the expected R 2 (2)(8) graph-set motif.

The title mol-ecular salt, C10H12N3O3S(+)·C7H3N2O7 (-), protonation occurs at the amino N atom attached to the benzene ring of sulfamethoxazole. In the anion, there is an intra-molecular O-H⋯O hydrogen bond and the cation is linked to the anion by an N-H⋯O hydrogen bond. In the extended structure, the cations and anions are linked via N-H⋯O, N-H⋯N and C-H⋯O hydrogen bonds, forming a three-dimensional framework.

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.

In the title compound, C13H10ClNO, the dihedral angle between the planes of the aromatic rings is 51.42 (9)° and an intra-molecular O-H⋯N hydrogen bond closes an S(6) ring. The Cl atom and the N atom are syn. No directional inter-actions beyond van der Waals contacts are observed in the crystal.

The title compound, C5H6N4O, is approximately planar, with an angle of 11.04 (15)° between the planes of the pyrimidine ring and the non-H atoms of the carboximidamide unit. The mol-ecule adopts an E configuration about the C=N double bond. In the crystal, adjacent mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(10) ring motif. The dimers are further linked via N-H⋯N and O-H⋯N hydrogen bonds into a sheet structure parallel to the ac plane. The crystal structure also features N-H⋯O and weak C-H⋯O hydrogen bonds and offset π-π stacking inter-actions between adjacent pyrimidine rings [centroid-centroid distance = 3.622 (1) Å].

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.

In the title complex, [Co(CO3)(NH3)4]ClO4, both the cation and anion lie on a mirror plane. The Co(III) ion is coordinated by two NH3 ligands and a chelating carbonato ligand in the equatorial sites and by two NH3 groups in the axial sites, forming a distorted octa-hedral geometry. In the crystal, N-H⋯O hydrogen bonds connect the anions and cations, forming a three-dimensional network.

In the crystal structure of the title compound, C(6)H(10)N(3) (+)·C(7)H(2)I(3)O(2) (-)·C(7)H(3)I(3)O(2), two R(2) (2)(8) motifs are observed. One is generated by the inter-action of the 2-amino-4,6-dimethyl-pyrimidin-1-ium cation with the carboxyl-ate group of the 2,3,5-triiodo-benzoate anion via N-H⋯O hydrogen bonds. The other R(2) (2)(8) motif is formed by the inter-action of two centrosymmentrically related pyrimidine moieties through N-H⋯N hydrogen bonds. The two motifs combine to form a linear heterotetra-meric unit. Heterotetra-meric units are linked by a carbox-yl-carboxyl-ate O-H⋯O hydrogen bond (involving the O-H group of neutral 2,3,5-triiodo-benzoic acid and an O atom of the anion), forming a supra-molecular chain along the a axis. In addition, components are held by weak I⋯O interactions in the range 3.023 (5) to 3.382 (5) Å and I⋯I inter-actions in the range 3.6327 (7) to 4.0025 (8) Å.

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.

In the crystal of the title compound C(10)H(17)NO, synthesized by the reaction of β-cyclo-citral with hydroxyl-amine hydro-chloride, inversion-related mol-ecules are linked by a pair of O-H⋯N hydrogen-bonding inter-actions between the oxime functionalities, forming R(2) (2)(6) loops. The molecular conformation is stabilized by intra-molecular methyl C-H⋯N inter-actions. The cyclohexene ring has the typical half-chair conformation.

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].

The cation and anion of the title mol-ecular salt, C(7)H(10)NO(+)·C(6)H(2)N(3)O(8) (-), are linked via an N-H⋯O hydrogen bond. An intra-molecular O-H⋯O hydrogen bond is also found in the anion. In the crystal, the anions self-assemble via O-H⋯O hydrogen bonds, forming a C(9) supra-molecular chain the b axis. Further inter-molecular N-H⋯O inter-actions also occur.

In the title complex, [ZnBr(2)(C(4)H(5)N(3)O)(2)], the central metal ion is coordinated to two bromide ions and endocyclic N atoms of the two cytosine mol-ecules leading to a distorted tetra-hedral geometry. The structure is isotypic with [CdBr(2)(C(4)H(5)N(3)O)(2)] [Muthiah et al. (2001). Acta Cryst. E57, m558-m560]. There are two inter-ligand N-H⋯Br hydrogen bonds, generating two hydrogen-bonded rings stabilizing the coordination sphere. The complex aggregates, forming supra-molecular chains, sheets and staircases through N-H⋯O and N-H⋯Br hydrogen bonding and π-π stacking inter-actions [centroid-centroid distance = 3.616 (2) Å].

In the title co-crystal C(6)H(9)N(3)O(2)·C(10)H(9)NO(2), the 4,6-dimeth-oxy-pyrimidin-2-amine mol-ecule inter-acts with the carboxyl group of the 2-(1H-indol-3-yl)acetic acid mol-ecule through N-H⋯O and O-H⋯N hydrogen bonds, forming a cyclic hydrogen-bonded R(2) (2)(8) motif, which is further linked by an N-H⋯N hydrogen bond, forming a supra-molecular chain along the c axis. Neighboring chains are inter-linked via C-H⋯O hydrogen bonds, forming a supra-molecular ladder.

The title compound, C(17)H(15)N(3)O(4)S, is a monoclinic polymorph with space group P2(1)/c of the previously reported triclinic form in P [Subashini et al. (2009 ▶). J. Chem. Crystallogr.39, 112-116]. In both polymorphs, intra-molecular O-H⋯N hydrogen bonds and dimer formation via a pair of inter-molecular N-H⋯N hydrogen bonds with an R(2) (2)(8) motif are observed. The two polymorphs differ in the next level of supra-molecular organization involving C-H⋯O hydrogen bonds with varied packing and different conformations.

In 2,4-diamino-6-methyl-1,3,5-triazin-1-ium (acetoguanaminium) hydrogen phthalate, C(4)H(8)N(5)(+) x C(8)H(5)O(4)(-), (I), acetoguanaminium hydrogen maleate, C(4)H(8)N(5)(+) x C(4)H(3)O(4)(-), (II), and acetoguanaminium 3-hydroxypicolinate monohydrate, C(4)H(8)N(5)(+) x C(6)H(4)NO(3)(-) x H(2)O, (III), the acetoguanaminium cations interact with the carboxylate groups of the corresponding anions via a pair of nearly parallel N-H...O hydrogen bonds, forming R(2)(2)(8) ring motifs. In (II) and (III), N-H...N base-pairing is observed, while there is none in (I). In (II), a series of fused R(3)(2)(8), R(2)(2)(8) and R(3)(2)(8) hydrogen-bonded rings plus fused R(2)(2)(8), R(6)(2)(12) and R(2)(2)(8) ring motifs occur alternately, aggregating into a supramolecular ladder-like arrangement. In (III), R(2)(2)(8) motifs occur on either side of a further ring formed by pairs of N-H...O hydrogen bonds, forming an array of three fused hydrogen-bonded rings. In (I) and (II), the anions form a typical intramolecular O-H...O hydrogen bond with graph set S(7), whereas in (III) an intramolecular hydrogen bond with graph set S(6) is formed.

In 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium (pyrimethaminium, PMNH) 4-methylbenzoate, C(12)H(14)ClN(4)(+) x C(8)H(7)O(2)(-), (I), pyrimethaminium 3-hydroxypicolinate, C(12)H(14)ClN(4)(+) x C(6)H(4)NO(3)(-), (II), and pyrimethaminium 2,4-dichlorobenzoate, C(12)H(14)ClN(4)(+) x C(7)H(3)Cl(2)O(2)(-), (III), the PMNH cations interact with the carboxylate groups of the corresponding anion via nearly parallel N-H...O hydrogen bonds, forming R(2)(2)(8) ring motifs. A description of the observed arrays of quadruple hydrogen bonds in (I) and (II) in terms of hydrogen donors and acceptors (the DA model), their graph-set motifs and the resulting supramolecular ladder is given. In (III), supramolecular chains along the b axis and helical chains along the a axis are formed via N-H...O hydrogen bonds involving the 2-amino and 4-amino groups of the PMNH cation, respectively. Weak Cl...Cl interactions are also found in (III).

In the title 1:1 adduct, C(6)H(9)N(3)·C(7)H(7)NO(2), the crystal structure is stabilized by hydrogen bonds involving two different R(2) (2)(8) motifs. One of them is formed by the inter-action of 2-amino-4,6-dimethyl-pyrimidine (AMPY) with the carboxyl group of anthranilic acid (AA) through N-H⋯O and O-H⋯N hydrogen bonds, whereas the other is formed through the inter-action of two centrosymmetrically related pyrimidines involving N-H⋯N hydrogen bonds. These two combined motifs form a heterotetra-mer. The heterotetra-mer sheets are stacked into three-dimensional network.

In the title compound, [U(C(9)H(4)INO(4)S)O(2)(H(2)O)(3)].2H(2)O, the asymmetric unit contains a UO(2)(2+) ion coordinated by the N and O atoms of a 7-iodo-8-oxidoquinoline-5-sulfonate dianion (ferron anion) and three coordinated water molecules, and two uncoordinated water molecules. The UO(2)(2+) ion exhibits a seven-coordinate pentagonal bipyramidal geometry. The usual sulfonate oxygen coordination is absent but the sulfonate O atoms, along with the coordinated and lattice water molecules, play a vital role in assembling the three-dimensional structure via an extensive network of intermolecular O-H...O hydrogen bonds and pi-pi stacking interactions.

In the crystal structures of 2-amino-4,6-dimethoxypyrimidinium 2,4,6-trinitrophenolate (picrate), C(6)H(10)N(3)O(2)(+).C(6)H(2)N(3)O(7)(-), (I), and 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium (pyrimethaminium or PMN) picrate dimethyl sulfoxide solvate, C(12)H(14)ClN(4)(+).C(6)H(2)N(3)O(7)(-).C(2)H(6)OS, (II), the 2-amino-4,6-dimethoxypyrimidine and PMN cations are protonated at one of the pyrimidine N atoms. The picrate anion interacts with the protonated cations through bifurcated N-H...O hydrogen bonds, forming R(2)(1)(6) and R(1)(2)(6) ring motifs. In (I), Z' = 2. In (II), two inversion-related PMN cations are connected through a pair of N-H...N hydrogen bonds involving the 4-amino group and the uncharged N atom of the pyrimidine ring, forming a cyclic hydrogen-bonded R(2)(2)(8) motif. In addition to the pairing, the O atom of the dimethyl sulfoxide solvent molecule bridges the 2-amino and 4-amino groups on both sides of the paired bases, resulting in a self-complementary ...DADA... array of quadruple hydrogen-bonding patterns.

In the title compound, C(6)H(10)N(3) (+)·C(7)H(3)N(2)O(6) (-)·2H(2)O, the amino-pyrimidine mol-ecule is protonated at one of the pyrimidine N atoms. The carboxyl-ate group of the 3,5-dinitro-benzoate anion inter-acts with the protonated pyrimidine N atom and the 2-amino group through a pair of N-H⋯O hydrogen bonds, forming an R(2) (2)(8) motif. Two inversion-related pyrimidine rings are linked via a pair of N-H⋯N hydrogen bonds, also forming an R(2) (2)(8) ring motif.

Background: Trimethoprim [2,4-diamino-5-(3',4',5'-trimethoxybenzyl)pyrimidine] is an antifolate drug. It selectively inhibits the bacterial dihydrofolate reductase (DHFR) enzyme., Results: In the crystal structures of trimethoprim (TMP)-hydrogen phthalate (1) and trimethoprim-hydrogen adipate (2), one of the N atoms of the pyrimidine ring is protonated and it interacts with the deprotonated carboxylate oxygens through a pair of nearly parallel N-H...O hydrogen bonds to form a fork-like interaction. In the compound 1, the pyrimidine moieties of the TMP cations are centrosymmetrically paired through a pair of N-H...N hydrogen bonds involving 4-amino group and the N (N3) atom of the pyrimidine rings to form a 8-membered hydrogen bonded ring [R2(2)(8)]. The 4-amino group of one TMP moiety and 2-amino group of another TMP moiety (both moieties are members of a base pair) are bridged by the carbonyl oxygen of the phthalate moiety through N-H...O hydrogen bonds forming 8-membered hydrogen-bonded ring [R2(2)(8)]. The characteristic hydrogen-bonded rings observed in the structure aggregate into a supramolecular ladder consisting of a pair of chains, each of which is built up of alternate TMP and hydrogen phthalate ions. In the compound 2, two TMP cations and two hydrogen adipate anions are arranged about an inversion center so that the complementary DDAA (D = donor, A = acceptor) arrays of quadruple hydrogen-bonding patterns are formed. The head-to-tail arrangement of the hydrogen adipate ions leads to a hydrogen-bonded supramolecular chain. From crystal engineering point of view, it is interesting to note that the compound 1 has a hydrogen-bonded network remarkably identical with its aliphatic analogue, trimethoprim hydrogen maleate. Similarly the compound 2, resembles its homolog trimethoprim hydrogen glutarate., Conclusion: In the crystal structure of trimethoprim hydrogen phthalate, the hydrogen-bonded network is remarkably identical with its aliphatic analogue, trimethoprim hydrogen maleate. Similarly in the crystal structure of trimethoprim hydrogen adipate the hydrogen bonded network resembles its homolog trimethoprim hydrogen glutarate.

In the title compound, C6H10N3+.HSO4-, the asymmetric unit consists of a hydrogen sulfate anion and a 2-amino-4,6-dimethylpyrimidinium cation. The hydrogen sulfate anions self-assemble through O-H...O hydrogen bonds, forming supramolecular chains along the b axis, while the organic cations form base pairs via N-H...N hydrogen bonds. The aminopyrimidinium cations join to the sulfate anions via a pair of hydrogen bonds donated from the pyrimidinium protonation site and from the exo amine group cis to the protonated site.

The title compound, trimethoprim (TMP) formate [systematic name: 2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium formate], C(14)H(19)N(4)O(3)(+).CHO(2)(-), reveals a pseudo-quadruple hydrogen-bonding motif consisting of six N-H.O hydrogen bonds involving two unpaired TMP cations and two formate anions which are symmetrically disposed. The hydrogen-bonding motif is strikingly comparable with that observed in other TMP salts where the aminopyrimidine moieties of the TMP cations are centrosymmetrically paired. These conserved hydrogen-bonding motifs may serve as robust synthons in crystal engineering and design. The characteristic pseudo-quadruple hydrogen-bonding motif and other intermolecular hydrogen bonds operating in the crystal form a two-dimensional supramolecular sheet structure.