N‐(6‐Bromo‐4‐oxo‐3,4‐di­hydro­pteridin‐2‐yl)‐2,2‐di­methyl­propan­amide

In the title compound, C₁₁H₁₂BrN₅O₂, the rings in the pterin moiety are planar. The carbonyl O atom is in a synperiplanar conformation, while the C—N—C(=O)—C linkage is antiperiplanar. N—H?N and N—H?O intermolecular hydrogen bonds transform the mol­ecules into infinite chains.     

Piperidinium 3‐[(4‐hydroxy‐5,7‐di­methyl‐2‐oxo‐2H‐chromen‐3‐yl)­phenyl­methyl]‐5,7‐di­methyl‐2‐oxo‐2H‐chromen‐4‐olate

In the title salt, C₅H₁₂N⁺·C₂₉H₂₃O₆^?, both benzo­pyran systems are planar. Intermolecular N—H?O hydrogen bonds and a short O—H?O intramolecular hydrogen bond are observed in the structure.     

2‐(4‐Acetyl‐3,5‐di­hydroxy‐2‐methyl­phenoxy)‐4,6‐di­methoxy‐3‐methyl­benzoic acid

In the title compound, C₁₉H₂₀O₈, the benzene rings are nearly perpendicular to each other [dihedral angle 80.2 (2)°]. The carboxy group is twisted out while both the methoxy and acetyl groups are almost coplanar with their attached benzene rings. The hydroxy group is involved in an intramolecular O—H?O hydrogen bond with the acetyl O atom and the compound is connected through an intermolecular O—H?O contact to form a dimer. The crystal structure is stabilized by intermolecular O—H?O hydrogen bonds.     

3‐(p‐Chloro­phenyl)‐4‐phenyl‐4,5‐di­hydro­isoxazole‐5‐spiro‐2′‐1′,2′,3′,4′‐tetra­hydro­naphthalen‐1′‐one

In the title compound, C₂₄H₁₈ClNO₂, the phenyl ring and the tetralone moiety are approximately orthogonal to the isoxazoline ring. The isoxazoline ring adopts an envelope conformation, while the cyclo­hexenone ring of the tetralone moiety has an intermediate sofa/half‐chair conformation. In this structure, one C—H?N intermolecular and two C—H?O intramolecular hydrogen bonds occur; the H?A distances are 2.60, and 2.35 and 2.57 Å, respectively. The mol­ecules are held together by an intermolecular C—H?N hydrogen bond, forming a one‐dimensional chain along the [100] direction.     

2′,4′‐Di­hydroxy‐3‐methoxy‐α,β‐di­hydro­chalcone and 2′,4‐di­hydroxy‐α,β‐di­hydro­chalcone: supramolecular structures formed by O—H⋯O,C—H⋯O and stacking interactions

The crystal structures of 2′,4′‐di­hydroxy‐3‐methoxy‐α,β‐di­hydro­chalcone, C₁₆H₁₆O₄, and 2′,4‐di­hydroxy‐α,β‐di­hydro­chalcone, C₁₅H₁₄O₃, have been determined. In both compounds, the structure consists of two nearly planar six‐membered aromatic rings connected by a propanal chain, which is bent in the methoxy compound and almost straight in the other compound. In the crystal structures, the molecular units of both compounds are linked by O—H⋯O hydrogen bonds to form infinite one‐dimensional chains. Hydro­gen bonds and C—H⋯O contacts in the crystal structures were studied by topological analysis of charge density based on Hartree–Fock calculations. Almost all of the investigated C—H⋯O contacts should be characterized as weak hydrogen bonds.     

N,N‐Di­methyl­anilinium 3‐cyano‐4‐(di­cyano­methyl­ene)‐5‐oxo‐4,5‐di­hydro‐1H‐pyrrol‐2‐olate

In the title compound, C₈H₁₂N⁺·C₈HN₄O₂⁻, the anion and cation lie on a crystallographic mirror plane and form planar ribbons via N—H⋯O [N⋯O = 2.933 (4) Å, H⋯O = 2.01 Å and N—H⋯O = 170°] and N—H⋯N [N⋯N = 3.016 (5) Å, H⋯N = 2.15 Å and N—H⋯N = 169°] hydrogen bonds. The ribbons are further linked via weak C—H⋯O and C—H⋯N hydrogen bonds. In adjacent planes, anions lie opposite cations; π–π interactions (separation a/2 = 3.520 Å) exist between the anions and the cations, and stacks are formed, running along the a axis. The cations are disordered over two interpenetrating sites, with occupancies of 0.833 (5) and 0.167 (5).     

The new chiral ligand 3‐ethoxy‐4‐[(1R,2S)‐(2‐hydroxy‐1,2‐di­phenyl­ethyl)­amino]‐3‐cyclo­butene‐1,2‐dione

The asymmetric unit of C₂₀H₁₉NO₄ contains two mol­ecules with slightly different conformations. In the crystal, the mol­ecules are linked by O—H?O and N—H?O hydrogen bonds [O?O 2.764 (3) and 2.811 (3) Å; N?O 2.907 (3) and 2.968 (3) Å] to form a two‐dimensional network.     

The ternary complex 4‐(2‐pyridyl)pyridinium–3,5‐di­nitro­benzoate–3,5‐di­nitro­benzoic acid (1/1/1)

In the title ternary complex, C₁₀H₉N₂⁺·C₇H₃N₂O₆^?·C₇H₄N₂O₆, the pyridinium cation adopts the role of the donor in an intermolecular N—H?O hydrogen‐bonding interaction with the carboxyl­ate group of the 3,5‐di­nitro­benzoate anion. The mol­ecules of the ternary complex form molecular ribbons perpendicular to the b direction, which are stabilized by one N—H?O, one O—H?O and five C—H?O intermolecular hydrogen bonds. The ribbons are further interconnected by three intermolecular C—H?O hydrogen bonds into a three‐dimensional network.     

6‐(1‐Hydro­xy‐2,2‐di­phenyl­ethyl)‐4,4‐di­phenyl‐2‐cyclo­hexen‐1‐one

The crystal structure of the title compound, C₃₂H₂₈O₂, (I), confirms the erythro stereochemistry of the aldol adduct. In the crystal, (I) forms centrosymmetric O—H?O=C hydrogen‐bonded dimers which in turn are connected by C—H?O and C—H?π interactions.     

Chains of fused rings in the hydrogen‐bonded structure of meso‐­6,13‐di­amino‐6,13‐di­methyl‐1,4,8,11‐tetra­aza­cyclo­tetra­decane–2,2′‐biphenol (1/2)

The title compound is a salt, [C₁₂H₃₂N₆]²⁺·2[HOC₆H₄C₆H₄O]^?. The centrosymmetric cation contains two intramolecular N—H?N hydrogen bonds with an N?N distance of 2.8290 (13) Å, and the pendent amino groups are in axial sites; the anion contains an intramolecular O—H?O hydrogen bond with an O?O distance of 2.4656 (11) Å. The ions are linked into continuous chains by means of four types of N—H?O hydrogen bonds with N?O distances ranging from 2.7238 (12) Å to 3.3091 (13) Å, associated with N—H?O angles in the range 148–160°.     

(+)‐2‐(1,2,3,4,4a,5,6,7‐Octa­hydro‐4a,8‐di­methyl‐7‐oxo‐2‐naphthyl)­propionic acid: catemeric hydrogen bonding in a bicyclic sesquiterpenoid keto acid

The title compound, C₁₅H₂₂O₃, derived from a naturally occurring sesquiterpenoid, has two mol­ecules in the asymmetric unit, differing principally in the rotational conformation of the carboxyl group. Each species aggregates separately as a carboxyl‐to‐ketone hydrogen‐bonding catemer [O?O = 2.752 (4) and 2.682 (4) Å, and O—H?O = 161 (4) and 168 (4)°], producing two crystallographically independent single‐strand hydrogen‐bonding helices, with opposite end‐to‐end orientations, passing through the cell in the b direction. Three intermolecular C—H?O=C close contacts exist for the ketone.     

Intermolecular O—H⃛O hydrogen bonding in the three independent molecules of (2S)‐3‐(4‐hydroxyphenyl)‐2‐(1‐oxoisoindolin‐2‐yl)­propanoic acid

The title compound, C₁₇H₁₅NO₄, derived from l ‐tyrosine, crystallizes with three independent mol­ecules which differ in the conformation of the asymmetric unit: the N—C—C—C_ipso torsion angles are ?71.7 (5), ?63.6 (6) and ?52.5 (5)°, respectively. Deformations in the phenol ring hydroxy O—C—C angles of 116.5 (4)/123.9 (4), 121.7 (5)/118.1 (4) and 122.4 (5)/118.6 (5)°, respectively, result from their respective intermolecular hydrogen‐bonding environments. Intermolecular O_acid—H?O=C_indole, O_phenol—H?O—H_phenol and O_phenol—H?O=C_indole hydrogen bonds, with O?O distances in the range 2.607 (4)–2.809 (4) Å, are present in combination with C—H?O and C—H?π_arene interactions. The primary hydrogen‐bonding systems assemble with graph sets R₃³(8) and R₃²(22).     

4‐Ethoxycarbonyl‐3‐hydroxy‐3‐phenylcyclohexanone

The title compound, ethyl 2‐hydroxy‐4‐oxo‐2‐phenyl­cyclo­hexane­carboxyl­ate, C₁₅H₁₈O₄, was obtained by a Michael–Aldol condensation and has the cyclo­hexanone in a chair conformation. The attached hydroxy, ethoxy­carbonyl and phenyl groups are disposed in β‐axial, β‐equatorial and α‐­equatorial configurations, respectively. An intermolecular hydrogen bond, with an O?O distance of 2.874 (2) Å, links the OH group and the ring carbonyl. Weak intermolecular C—H?O=C (ester and ketone), O—H?O=C (ketone) and C—H?OH hydrogen bonds exist.     

3‐(4‐Bromo­phenyl)‐2‐(3,4‐di­hydro‐2H‐pyran‐5‐yl)‐1,1,1‐tri­fluoro­propan‐2‐ol

The molecular structure of the title compound, C₁₄H₁₄BrF₃O₂, adopts a bent conformation. Intramolecular O—H?F and intermolecular O—H?O interactions form a bifurcated hydrogen bond which produces a supramolecular assembly of head‐to‐tail dimers.     

Supramolecular structures of 5‐[3‐(4‐methyl­phenyl)‐ and 5‐[3‐(4‐chloro­phenyl)‐2‐propenyl­idene]‐2,2‐di­methyl‐1,3‐dioxane‐4,6‐dione

2,2‐Di­methyl‐5‐[3‐(4‐methyl­phenyl)‐2‐propenyl­idene]‐1,3‐di­ox­ane‐4,6‐dione, C₁₆H₁₆O₄, crystallizes in the triclinic space group , with two mol­ecules in the asymmetric unit. These mol­ecules and a centrosymmetrically related pair, linked together by weak C—H?O hydrogen bonds, form a tetramer. 5‐[3‐(4‐Chloro­phenyl)‐2‐propenyl­idene]‐2,2‐di­methyl‐1,3‐dioxane‐4,6‐dione, C₁₅H₁₃ClO₄, also crystallizes in the triclinic space group , with one mol­ecule in the asymmetric unit. Centrosymmetrically related mol­ecules are linked together by weak C—H?O hydrogen bonds to form dimers which are further linked by yet another pair of centrosymmetrically related C—H?O hydrogen bonds to form a tube which runs parallel to the a axis.     

1‐(2‐Hydroxy‐4,6‐di­methyl­phenyl)­ethanone

In the crystal of the title compound, C₁₀H₁₂O₂, there are two symmetry‐independent mol­ecules, which are essentially superimposable. Each mol­ecule exhibits an intramolecular O—H?O hydrogen bond, with O?O separations of 2.483 (4) and 2.468 (4) Å.     

N‐(2‐Amino‐1,6‐di­hydro‐5‐nitro­so‐6‐oxopyrimidin‐4‐yl)‐l‐isoleucine–water (4/1): interplay of molecular and supramolecular structures

In the title compound, 2C₁₀H₁₅N₅O₄·0.5H₂O, there are two independent mol­ecules of the pyrimidinyl­isoleucine in general positions and a water mol­ecule lying on a twofold rotation axis. The bond lengths within the organic moieties demonstrate significant polarization of the electronic structure. Each of the organic mol­ecules participates in 12 intermolecular hydrogen bonds, of O—H?O and N—H?O types, while the water mol­ecule acts as a double donor and as a double acceptor of O—H?O hydrogen bonds. The organic components are linked by the hydrogen bonds into a single three‐dimensional framework, reinforced by the water mol­ecules.     

N1‐(4‐tert‐Butyl­phenyl)‐N2‐hydroxy‐α‐oxo‐α‐phenyl­acet­amidine and N2‐hydroxy‐N1‐(4‐nitro­phenyl)‐α‐oxo‐α‐phenyl­acet­amidine hemihydrate

In the title compounds, C₁₈H₂₀N₂O₂, (I), and C₁₄H₁₁N₃O₄·0.5H₂O, (II), respectively, the oxime groups have an E configuration. In (I), the mol­ecules exist as polymers bound by intermolecular C—H⋯O and O—H⋯N hydrogen bonds around inversion centres. In (II), intermolecular OW—H⋯N, OW—H⋯O and O—H⋯OW interactions stabilize the molecular packing.     

2,8‐Di­hydroxy‐1,3,7,9‐tetra­methyl‐6,12‐di­hydro­dipyrido­[1,2‐a:1′,2′‐d]pyrazine­diyl­ium dichloride dihydrate

The 2,8‐di­hydroxy‐1,3,7,9‐tetra­methyl‐6,12‐di­hydro­di­pyrido[1,2‐a:1′,2′‐d]pyrazine­diyl­ium dication possesses 2/m symmetry and lies in the mirror plane together with a chloride anion and the water O atom. The dication also lies on an inversion centre, i.e. C₁₆H₂₀N₂O₂²⁺·2Cl^?·2H₂O. Due to these symmetry constrictions the dication adopts an unexpected planar conformation. Molecules are linked by O—H?O and O—H?Cl hydrogen bonds to form chains, which are cross‐connected by C—H?Cl attractive interactions forming a complex three‐dimensional hydrogen‐bond network.     

3‐Acetyl‐4‐benzoyl‐2‐methyl‐5‐phenyl‐3,3a‐di­hydro­pyrazolo­[2,3‐c]pyrimidine‐7(6H)‐thione

The mol­ecule of the title compound, C₂₂H₁₉N₃O₂S, is not planar. The dihedral angle between the two phenyl rings is 27.46 (7)° and in the di­hydro­pyrazolo­pyrimidine ring the total puckering amplitude Q_T is 0.526 (3) Å. The structure is stabilized by both intra‐ and intermolecular C—H?O interaction, and by an intermolecular N—H?S hydrogen bond.