PubMed Health⌕ Search

Biomedical subjects

John N Low

Publications and source records attributed to John N Low.

At least 19 recordsLinked to original sources
PubMed2006

2,3-Dimethoxybenzaldehyde isonicotinoylhydrazone chloroform monosolvate, and the mono- and dihydrates of 3,4,5-trimethoxybenzaldehyde isonicotinoylhydrazone: hydrogen-bonded supramolecular structures in one, two and three dimensions.

In 2,3-dimethoxybenzaldehyde isonicotinoylhydrazone chloroform monosolvate, C15H15N3O3.CHCl3, the hydrazone molecules are linked by a combination of N-H...N and C-H...N hydrogen bonds into chains from which the chloroform molecules are pendent. 3,4,5-Trimethoxybenzaldehyde isonicotinoylhydrazone forms two stoichiometric hydrates. In the monohydrate, C16H17N3O4.H2O, the components are linked into sheets by a combination of O-H...O, O-H...N and N-H...N hydrogen bonds, and in the dihydrate, C16H17N3O4.2H2O, a combination of O-H...O, O-H...N and N-H...O hydrogen bonds links the components into a three-dimensional framework structure.

Journal Article↗
PubMed2006

Hydrogen-bonded chains of rings in methyl 4-[(5-methyl-1H-pyrazol-3-yl)amino]-3-nitrobenzoate and hydrogen-bonded sheets in methyl 1-(5-methyl-1H-pyrazol-3-yl)-1H-benzimidazole-5-carboxylate.

Molecules of methyl 4-[(5-methyl-1H-pyrazol-3-yl)amino]-3-nitrobenzoate, C12H12N4O4, (I), exhibit a polarized (charge-separated) structure in the nitroaniline portion. The molecules are linked into chains of edge-fused R(2)2(16) and R(2)2(22) rings by a combination of N-H...O(carbonyl) and C-H...O(nitro) hydrogen bonds. Methyl 1-(5-methyl-1H-pyrazol-3-yl)-1H-benzimidazole-5-carboxylate, C13H12N4O2, (II), which is readily formed from (I) by reduction followed by ring formation, crystallizes with Z' = 2 in the space group P-1. Each of the two independent molecular types is linked into sheets of R(4)4(28) rings by a combination of N-H...N and C-H...O(carbonyl) hydrogen bonds.

Benzimidazoles↗
PubMed2006

Three ethyl 5-amino-1-aryl-1H-imidazole-4-carboxylates: hydrogen-bonded supramolecular structures in one, two and three dimensions.

The molecules of ethyl 5-amino-1-(4-cyanophenyl)-1H-imidazole-4-carboxylate, C13H12N4O2, are linked into a chain of alternating R(2)2(10) and R(4)4(34) rings by a combination of N-H...N and C-H...N hydrogen bonds. In ethyl 5-amino-1-(4-chlorophenyl)-1H-imidazole-4-carboxylate, C12H12ClN3O2, where the ethyl group is disordered over two sets of sites, a combination of N-H...O, N-H...N, C-H...N and C-H...pi(arene) hydrogen bonds links the molecules into complex sheets. Two intermolecular hydrogen bonds, one each of N-H...N and C-H...O types, link the molecules of ethyl 5-amino-1-(2,6-difluorophenyl)-1H-imidazole-4-carboxylate, C12H11F2N3O2, into a continuous three-dimensional framework structure.

Amination↗
PubMed2006

Hydrogen-bonded chains in 3-tert-butyl-5-[(4-methoxybenzyl)amino]-1-phenyl-1H-pyrazole and tetramolecular hydrogen-bonded aggregates in 5-[(benzotriazol-1-ylmethyl)(4-methoxybenzyl)amino]-3-tert-butyl-1-phenyl-1H-pyrazole.

The molecules of 3-tert-butyl-5-[(4-methoxybenzyl)amino]-1-phenyl-1H-pyrazole, C21H25N3O, are linked into simple C9 chains by a single C-H...N hydrogen bond. 5-[(Benzotriazol-1-ylmethyl)(4-methoxybenzyl)amino]-3-tert-butyl-1-phenyl-1H-pyrazole, C28H30N6O, crystallizes with Z' = 2 in the space group P2(1)/c. The molecules are weakly linked into centrosymmetric tetramolecular aggregates by a combination of C-H...N and C-H...O hydrogen bonds.

Journal Article↗
PubMed2006

Three substituted 4-pyrazolylbenzoates: hydrogen-bonded supramolecular structures in one, two and three dimensions.

The molecules of ethyl 4-(5-amino-3-methyl-1H-pyrazol-1-yl)benzoate, C13H15N3O2, are linked by two independent N-H...O hydrogen bonds into a chain of edge-fused and alternating R(4)2(8) and R(2)2(20) rings. A combination of N-H...N and N-H...O hydrogen bonds links the molecules of methyl 4-(5-amino-3-tert-butyl-1H-pyrazol-1-yl)benzoate, C15H19N3O2, into sheets of alternating R(2)2(20) and R(6)6(32) rings. In 4-(5-amino-3-methyl-1H-pyrazol-1-yl)benzoic acid monohydrate, C11H11N3O2.H2O, the molecular components are linked into a three-dimensional framework structure by a combination of five independent hydrogen bonds, two of O-H...N type and one each of O-H...O, N-H...O and N-H...N types.

Azo Compounds↗
PubMed2006

Four substituted benzohydrazides: hydrogen-bonded structures in one, two and three dimensions.

The molecules of 2,6-dichlorobenzohydrazide, C7H6Cl2N2O, are linked into simple chains by a single N-H...O hydrogen bond, while in the isomeric compound 2,4-dichlorobenzohydrazide, the molecules are linked by N-H...N and N-H...O hydrogen bonds into complex sheets comprising an inner polar layer sandwiched between two non-polar layers. In 4-amino-2-chlorobenzohydrazide monohydrate, C7H8ClN3O.H2O, the components are linked into a three-dimensional framework by a combination of O-H...O, O-H...N, N-H...N and N-H...O hydrogen bonds, and in 2-nitrobenzohydrazide, C7H7N3O3, a three-dimensional framework is formed by a combination of N-H...N and N-H...O hydrogen bonds.

Journal Article↗
PubMed2006

Isomeric N-(iodophenyl)nitrobenzamides form different three-dimensional framework structures.

The isomeric N-(iodophenyl)nitrobenzamides, C(13)H(9)IN(2)O(3), all form different three-dimensional framework structures. Molecules of N-(2-iodophenyl)-3-nitrobenzamide (II) are linked by a combination of N-H...O and C-H...O hydrogen bonds and a two-centre iodo...carbonyl interaction. The supramolecular structure of N-(2-iodophenyl)-4-nitrobenzamide (III) is built from one N-H...O and two C-H...O hydrogen bonds, but short I...O contacts are absent from the structure. In N-(3-iodophenyl)-2-nitrobenzamide (IV), which crystallizes with Z' = 2 in space group P2(1), the structure contains two N-H...O hydrogen bonds, four C-H...O hydrogen bonds, two two-centre iodo...nitro interactions and an aromatic pi...pi stacking interaction. The structure of N-(3-iodophenyl)-3-nitrobenzamide (V) contains one N-H...O hydrogen bond and three C-H...O hydrogen bonds, together with a two-centre iodo...nitro interaction and an aromatic pi...pi stacking interaction, while in N-(3-iodophenyl)-4-nitrobenzamide (VI), the combination of one N-H...O hydrogen bond and two C-H...O hydrogen bonds is augmented not only by a two-centre iodo...nitro interaction and an aromatic pi...pi stacking interaction, but also by a dipolar carbonyl...carbonyl interaction. In the supramolecular structure of N-(4-iodophenyl)-4-nitrobenzamide (IX), which crystallizes with Z' = 2 in space group P\overline 1, there are two N-H...O hydrogen bonds, four C-H...O hydrogen bonds and two three-centre iodo...nitro interactions.

Journal Article↗
PubMed2006

3-[5-(4-Bromophenyl)-1H-pyrazol-3-ylamino]-5,5-dimethylcyclohex-2-en-1-one-(Z)-3-(4-bromophenyl)-3-chloroacrylonitrile (2/1): a stoichiometric cocrystal of a reaction product with one of its early precursors.

The title compound, 2C17H18BrN3O.C9H5BrClN, was crystallized from the reaction between 5,5-dimethylcyclohexane-1,3-dione, triethyl orthoformate and 5-amino-3-(4-bromophenyl)pyrazole, which had itself been prepared from the reaction between (Z)-3-(4-bromophenyl)-3-chloroacrylonitrile and hydrazine. The compound is a stoichiometric 2:1 cocrystal of the reaction product 3-[5-(4-bromophenyl)-1H-pyrazol-3-ylamino]-5,5-dimethylcyclohex-2-en-1-one and the early reactant (Z)-3-(4-bromophenyl)-3-chloroacrylonitrile. The two independent molecules of cyclohex-2-en-1-one are linked by N-H...N and N-H...O hydrogen bonds into complex bilayers and the molecules of acrylonitrile are trapped within large cavities in the substructure formed by the cyclohex-2-en-1-one molecules.

Journal Article↗
PubMed2006

Three substituted (E)-3-aryl-2-(thienyl)acrylonitriles: isolated molecules, simple hydrogen-bonded chains and hydrogen-bonded sheets.

The structure of (E)-2-(2-thienyl)-3-(3,4,5-trimethoxyphenyl)acrylonitrile, C16H15NO3S, contains no direction-specific intermolecular interactions. The molecules of (E)-3-(4-bromophenyl)-2-(2-thienyl)acrylonitrile, C13H8BrNS, exhibit orientational disorder of the thienyl fragment, and the molecules are linked into simple C(5) chains by a single C-H...N hydrogen bond. In (E)-3-phenyl-2-(3-thienyl)acrylonitrile, C13H9NS, the molecules are linked into sheets by a combination of one C-H...N hydrogen bond and one C-H...pi(arene) hydrogen bond.

Journal Article↗
PubMed2006

Isomers and polymorphs of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadienes.

The structures of five of the possible six isomers of (E,E)-1,4-bis(nitrophenyl)-2,3-diaza-1,3-butadiene are reported, including two polymorphs of one of the isomers. (E,E)-1,4-Bis(2-nitrophenyl)-2,3-diaza-1,3-butadiene, C(14)H(10)N(4)O(4) (I), crystallizes in two polymorphic forms (Ia) and (Ib) in which the molecules lie across centres of inversion in space groups P2(1)/n and P2(1)/c, respectively: the molecules in (Ia) and (Ib) are linked into chains by aromatic pi...pi stacking interactions and C-H...pi(arene) hydrogen bonds, respectively. Molecules of (E,E)-1-(2-nitrophenyl)-4-(3-nitrophenyl)-2,3-diaza-1,3-butadiene (II) are linked into sheets by two independent C-H...O hydrogen bonds. The molecules of (E,E)-1,4-bis(3-nitrophenyl)-2,3-diaza-1,3-butadiene (III) lie across inversion centres in the space group P2(1)/n, and a combination of a C-H...O hydrogen bond and a pi...pi stacking interaction links the molecules into sheets. A total of four independent C-H...O hydrogen bonds link the molecules of (E,E)-1-(3-nitrophenyl)-4-(4-nitrophenyl)-2,3-diaza-1,3-butadiene (IV) into sheets. In (E,E)-1,4-bis(4-nitrophenyl)-2,3-diaza-1,3-butadiene (V) the molecules, which lie across centres of inversion in the space group P2(1)/n, are linked by just two independent C-H...O hydrogen bonds into a three-dimensional framework.

Journal Article↗