PubMed Health⌕ Search

Biomedical subjects

Urs D Wermuth

Publications and source records attributed to Urs D Wermuth.

10 recordsLinked to original sources
PubMed2006

Proton-transfer and non-transfer in compounds of quinoline and quinaldic acid with L-tartaric acid.

The structures of two compounds of L-tartaric acid with quinoline, viz. the proton-transfer compound quinolinium hydrogen (2R,3R)-tartrate monohydrate, C9H8N+.C4H5O6-.H2O, (I), and the anhydrous non-proton-transfer adduct with quinaldic acid, bis(quinolinium-2-carboxylate) (2R,3R)-tartaric acid, 2C10H7NO2.C4H6O6, (II), have been determined at 130 K. Compound (I) has a three-dimensional honeycomb substructure formed from head-to-tail hydrogen-bonded hydrogen tartrate anions and water molecules. The stacks of pi-bonded quinolinium cations are accommodated within the channels and are hydrogen bonded to it peripherally. Compound (II) has a two-dimensional network structure based on pseudo-centrosymmetric head-to-tail hydrogen-bonded cyclic dimers comprising zwitterionic quinaldic acid species which are interlinked by tartaric acid molecules.

Journal Article↗
PubMed2006

Mixed dicationic and monocationic benzidine species in the proton-transfer compound of benzidine with 3,5-dinitrosalicylic acid.

The crystal structure of the proton-transfer compound of 1,1'-biphenyl-4,4'-diamine (benzidine) with 3,5-dinitrosalicylic acid, viz. 1,1'-biphenyl-4,4'-diaminium bis(4'-amino-1,1'-biphenyl-4-aminium) tetrakis(2-carboxy-4,6-dinitrophenolate) ethanol disolvate, C(12)H(14)N(2)(2+)x2C(12)H(13)N(2)(+)x4C(7)H(3)N(2)O(7)(-)x2C(2)H(6)O, shows the presence of both diprotonated and monoprotonated benzidine cations. The diprotonated species lie across crystallographic inversion centres in the unit cell, while the monoprotonated species occupy general sites. All amine H atoms participate in hydrogen bonding with carboxyl, phenolate and nitro O-atom acceptors of the salicylate anions, which also participate in hydrogen bonding with the disordered ethanol solvent molecules. Significant inter-ring anion-anion and anion-monocation pi-pi interactions are also present, giving a three-dimensional framework structure.

Journal Article↗
PubMed2006

Brucine salts of L-alpha-hydroxy acids: brucinium hydrogen (S)-malate pentahydrate and anhydrous brucinium hydrogen (2R,3R)-tartrate at 130 K.

The structures of two brucinium (2,3-dimethoxy-10-oxostrychnidinium) salts of the alpha-hydroxy acids L-malic acid and L-tartaric acid, namely brucinium hydrogen (S)-malate pentahydrate, C23H27N2O4+.C4H5O5-.5H2O, (I), and anhydrous brucinium hydrogen (2R,3R)-tartrate, C23H27N2O4+.C4H5O6-,(II), have been determined at 130 K. Compound (I) has two brucinium cations, two hydrogen malate anions and ten water molecules of solvation in the asymmetric unit, and forms an extensively hydrogen-bonded three-dimensional framework structure. In compound (II), the brucinium cations form the common undulating brucine sheet substructures, which accommodate parallel chains of head-to-tail hydrogen-bonded tartrate anion species in the interstitial cavities.

Crystallography, X-Ray↗
PubMed2005

Hydrogen bonding in brucinium dihydrogen citrate trihydrate at 130 K.

The structure of brucinium dihydrogen citrate trihydrate (systematic name: 2,3-dimethoxy-10-oxostrychnidinium dihydrogen citrate trihydrate), C(23)H(27)N(2)O(4)(+).C(6)H(7)O(7)(-).3H(2)O, has been determined at 130 K. The crystallographic asymmetric unit comprises two brucinium cations, two dihydrogen citrate anions and six water molecules of solvation. The two citrate anions, which are conformationally dissimilar, associate through extensive hydrogen-bonding interactions with the common undulating brucinium cation layer substructures and the water molecules, forming a three-dimensional framework polymer.

Journal Article↗
PubMed2005

Layered structures in proton-transfer compounds of 5-sulfosalicylic acid with the aromatic polyamines 2,6-diaminopyridine and 1,4-phenylenediamine.

The crystal structures of two proton-transfer compounds of 3-carboxy-4-hydroxybenzenesulfonic acid (5-sulfosalicylic acid) with the aromatic polyamines 2,6-diaminopyridine [namely 2,6-diaminopyridinium 3-carboxy-4-hydroxybenzenesulfonate monohydrate, C5H8N3+.C7H5O6S-.H2O, (I)] and 1,4-phenylenediamine [namely 1,4-phenylenediaminium 3-carboxylato-4-hydroxybenzenesulfonate, C6H10N2(2+).C7H4O6S2-, (II)] have been determined. Both compounds feature extensively hydrogen-bonded three-dimensional layered polymer structures having significant interlayer pi-pi interactions between the cation and anion species. In (I), the pyridine N atom of the Lewis base is protonated and forms a direct hydrogen-bonding interaction with the water molecule, which together with the two amine groups of the cation and the carboxylic acid group of the anion also give additional interactions with O-atom acceptors of the sulfonate group. In (II), a dianionic species results from deprotonation of both the sulfonic and the carboxylic acid groups, and all available O-atom acceptors interact with all dication donors, which lie about inversion centres.

Journal Article↗
PubMed2005

The proton-transfer compounds of strychnine with achiral salicylic acids: strychninium 3,5-dinitrosalicylate and the strychninium 5-nitrosalicylate bis(5-nitrosalicylic acid) adduct.

In the crystal structures of the proton-transfer compounds of strychnine with 3,5-dinitrosalicylic acid, namely strychninium 3,5-dinitrosalicylate, C21H23N2O2+.C7H3N2O7-, (I), and 5-nitrosalicylic acid, namely strychninium-5-nitrosalicylate-5-nitrosalicylic acid (1/1/2), C21H23N2O2+.C7H4NO5-.2C7H5NO5, (II), protonation of one of the N atoms of the strychnine molecule occurs and this group is subsequently involved in intermolecular hydrogen-bonding interactions. In (I), this is four-centred, the primary being with an adjacent strychninium carbonyl O-atom acceptor in a side-to-side interaction giving linear chains. Other interactions are with the phenolate and nitro O-atom acceptors of the anionic species, resulting in a one-dimensional polymer structure. In (II), the N+-H interaction is three-centred, the hydrogen bonding involving carboxyl O-atom acceptors of the anion and both acid adduct species, giving unique discrete hetero-tetramer units. The structure of (II) also features pi-bonding interactions between the two acid adduct molecules.

Journal Article↗
PubMed2005

Hydrogen bonding in 1:1 proton-transfer compounds of 5-sulfosalicylic acid with 4-X-substituted anilines (X = F, Cl or Br).

The crystal structures of three proton-transfer compounds of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with 4-X-substituted anilines (X = F, Cl and Br), namely 4-fluoroanilinium 5-sulfosalicylate (3-carboxy-4-hydroxybenzenesulfonate) monohydrate, C6H7FN+.C7H5O6S-.H2O, (I), 4-chloroanilinium 5-sulfosalicylate hemihydrate, C6H7ClN+.C7H5O6S-.0.5H2O, (II), and 4-bromoanilinium 5-sulfosalicylate monohydrate, C6H7BrN+.C7H5O6S-.H2O, (III), have been determined. The asymmetric unit in (II) contains two formula units. All three compounds have three-dimensional hydrogen-bonded polymeric structures in which both the water molecule and the carboxylic acid group are involved in structure extension. With both (II) and (III), which are structurally similar, the common cyclic R(2)(2)(8) dimeric carboxylic acid association is present, whereas in (I), an unusual cyclic R(3)(3)(8) association involving all three hetero-species is found.

Journal Article↗