ABSTRACT: Anhydrous 3,4,5-trihy-droxy-benzoic acid, C(7)H(6)O(5), is essentially planar, with its non-H atoms exhibiting mean and maximum deviations from coplanarity of 0.014 and 0.0377?(5)?Å, respectively. The C-C-C-OH torsion angle about the bond linking the carboxyl group to the benzene ring is -0.33?(10)°. In the crystal, the -COOH groups form centrosymmetric hydrogen-bonded cyclic dimers [graph set R(2) (2)(8)] and the phenolic -OH groups participate in both intra- and inter-molecular hydrogen bonds, forming a three-dimensional network structure.
Project description:IN THE TITLE COMPOUND (SYSTENATIC NAME: 3,4,5-trihy-droxy-benzoic acid pyridine monosolvate), C(5)H(5)N·C(7)H(6)O(5), the gallic acid mol-ecule is essentially planar (r.m.s deviation = 0.0766?Å for non-H atoms) and is linked to the pyridine mol-ecule by an O-H?N hydrogen bond. An intra-molecular O-H?O hydrogen bond occurs in the gallic acid mol-ecule. The gallic acid and pyridine mean planes make a dihedral angle 12.6?(3)°. Inter-molecular O-H?O and O-H?N hydrogen bonding involving the hy-droxy and carboxyl groups and the pyridine mol-ecule, and ?-? inter-actions between inversion-related pyridines [centroid-centroid distance = 3.459?(6)?Å] and between pyridine and benzene rings [centroid-centroid distance = 3.548?(6)?Å], lead to a three-dimensional network in the crystal.
Project description:The title compound, C(15)H(14)N(2)O(5)·CH(3)OH, displays an E conformation about the azomethine double bond [C=N = 1.277?(2)?Å] and the benzene rings are inclined to one another by 18.28?(9)°. An intra-molecular O-H?O hydrogen bond occurs between the para-OH group and one of the meta-O atoms of the 3,4,5-trihy-droxy-benzyl-idene group. In the crystal, the components are linked into a three dimensional network by O-H?O, O-H?N and C-H?O hydrogen bonds.
Project description:In the structure of the title complex, [Cu(C(7)H(5)O(2))(OH)(C(12)H(12)N(2))(C(7)H(6)O(2))]·H(2)O, the Cu(II) ion is penta-coordinated in a tetra-gonal-pyramidal geometry with one O atom of a hydroxide group, one O atom of a benzoate anion and two N atoms of a 4,4'-dimethyl-2,2'-bipyridine ligand occupying the basal plane, and one O atom of a benzoic acid mol-ecule located at the apical site. The title complex was refined with a metal-coordinated OH group and a 'free' benzoic acid molecule, although it can be assumed that the proton is delocalized between the OH and the COOH group. The uncoordinated water mol-ecule is equally disordered over two positions. The structure displays O-H?O hydrogen bonding.
Project description:Density functional theory models are used to examine five biodegradable ionic liquids (ILs) each one consisting of a substitutional group (-OH, -NH2, -COOH, -COOCH3, and -OCH3) incorporated into the cation of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]). The results reveal that hydrogen atoms in -NH2, -COOH, and -COOCH3 form intramolecular hydrogen bonds with fluorine atoms in [BF4]-, whereas hydrogen atoms in -OH and -OCH3 do not form hydrogen bonds with [BF4]-. Further analysis of electron density at bond critical points and noncovalent interactions suggest that [BMIM][BF4] with -COOH has stronger intramolecular hydrogen bonds than other ILs. The extraction mechanism for a model naphthenic acid is hydrogen bonding, with F···H being the strongest hydrogen bond and O···H ranking second. More intermolecular hydrogen bonds occur when model naphthenic acid is adsorbed by [BMIM][BF4] with -COOH and -COOCH3. The interaction energy between model naphthenic acid and ILs with -COOH and -COOCH3 is higher than that with -OH, -NH2, and -OCH3.
Project description:The title compound, C(14)H(19)NO(3), was prepared via the intra-molecular rearrangement of 3-(butanoyl-amino)-phenyl butano-ate in the presence of anhydrous aluminium chloride. The near coplanarity of the aromatic ring, the amide group and the carbonyl group of the butanoyl fragment [N-C-C-C = -179.65?(17) and O-C-C-C = -178.34?(17)°] results from the intra-molecular O-H?O and C-H?O hydrogen bonds. In the crystal, the mol-ecules form a one-dimensional polymeric structure via N-H?O inter-actions between their amide groups.
Project description:The title compound, C(9)H(18)NO(2) (+)·NO(3) (-), is an anhydrous nitrate salt of gabapentin, which is formed serendipitously in the presence of selected non-coordinating metals. The crystal structure involves extensive hydrogen bonding between the -NH(3) (+) and -COOH groups and the nitrate anion.
Project description:The asymmetric unit of the title compound, C(7)H(6)O(5)·0.25H(2)O, contains two mol-ecules of 2,3,4-trihy-droxy-benzoic acid, with similar conformations, and one water mol-ecule which lies on a twofold rotation axis. Both acid mol-ecules are essentially planar [maximum r.m.s deviations = 0.0324?(2) and 0.0542?(3)?Å for the two acid molecules]. The mol-ecular conformations are stabilized by intra-molecular O(phenol)-H?O(carbox-yl/phenol) inter-actions. A cyclic inter-molecular association is formed between the two acid and one water mol-ecule [graph set R(3) (3)(12)] involving O-H?O hydrogen bonds. The two acid mol-ecules are further linked through a cyclic R(2) (2)(8) carb-oxy-lic acid hydrogen-bonding association, which together with inter-molecular O-H?O hydrogen-bonding inter-actions involving the phenol groups and the water mol-ecule, and weak ?-? inter-actions [minimum ring centroid separation = 3.731?(3)?Å], give a three-dimensional network.
Project description:In the title compound, C(12)H(12)N(2)·2C(7)H(7)NO(2), the 4-amino-benzoic acid mol-ecules are linked by O-H?N hydrogen bonds to 1,2-bis-(4-pyrid-yl)ethane, forming linear hydrogen bonded chains parallel to . The structure exhibits a hydrogen-bonding network involving COOH?N(pyrid-yl) and amine and carb-oxy-lic N-H? O inter-actions. In addition, ?-? stacking inter-actions [centroid-centroid distance = 3.8622?(14)?Å] are also present.
Project description:The hydrogen-bonding environments at the COOH moiety in eight polycrystalline polymorphs of palmitic acid are explored using solid-state NMR. Although most phases have no previously reported crystal structure, measured 13C chemical shift tensors for COOH moieties, combined with DFT modeling establish that all phases crystallize with a cyclic dimer (R22(8)) hydrogen bonding arrangement. Phases A2, Bm and Em have localized OH hydrogens while phase C has a dynamically disordered OH hydrogen. The phase designated As is a mix of five forms, including 27.4% of Bm and four novel phases not fully characterized here due to insufficient sample mass. For phases A2, Bm, Em, and C the anisotropic uncertainties in the COOH hydrogen atom positions are established using a Monte Carlo sampling scheme. Sampled points are retained or rejected at the ±1? level based upon agreement of DFT computed 13COOH tensors with experimental values. The collection of retained hydrogen positions bear a remarkable resemblance to the anisotropic displacement parameters (i.e. thermal ellipsoids) from diffraction studies. We posit that this similarity is no mere coincidence and that the two are fundamentally related. The volumes of NMR-derived anisotropic displacement ellipsoids for phases with localized OH hydrogens are 4.1 times smaller than those derived from single crystal X-ray diffraction and 1.8 times smaller than the volume of benchmark single crystal neutron diffraction values.
Project description:The title hydrated tetrol, C(19)H(32)O(4)·3H(2)O, was synthesized by stereoselective reduction of the compound 3?,5?,6?-trihy-droxy-androstan-17-one. All rings are fused trans. The organic mol-ecules are connected head-to-tail along the c axis via O-H?O hydrogen bonds. Layers of water mol-ecules in the ab plane inter-connect these chains. A quantum chemical ab initio Roothan Hartree-Fock calculation of the isolated mol-ecule gives values for the mol-ecular geometry close to experimentally determined ones, apart from the C-O bond lengths, whose calculated values are significantly smaller than the measured ones, probably a consequence of the involvement of the C-OH groups in the hydrogen-bonding network.