Search PubMed⌕ Search

Biomedical subjects

John N Low

Publications and source records attributed to John N Low.

At least 37 records · Page 2Linked to original sources
PubMed2006

Nine N-aryl-2-chloronicotinamides: supramolecular structures in one, two and three dimensions.

Structures are reported here for eight further substituted N-aryl-2-chloronicotinamides, 2-ClC(5)H(3)NCONHC(6)H(4)X-4'. When X = H, compound (I) (C(12)H(9)ClN(2)O), the molecules are linked into sheets by N-H...N, C-H...pi(pyridyl) and C-H...pi(arene) hydrogen bonds. For X = CH(3), compound (II) (C(13)H(11)ClN(2)O, triclinic P1 with Z' = 2), the molecules are linked into sheets by N-H...O, C-H...O and C-H...pi(arene) hydrogen bonds. Compound (III), where X = F, crystallizes as a monohydrate (C(12)H(8)ClFN(2)O.H(2)O) and sheets are formed by N-H...O, O-H...O and O-H...N hydrogen bonds and aromatic pi...pi stacking interactions. Crystals of compound (IV), where X = Cl (C(12)H(8)Cl(2)N(2)O, monoclinic P2(1) with Z' = 4) exhibit inversion twinning: the molecules are linked by N-H...O hydrogen bonds into four independent chains, linked in pairs by C-H...pi(arene) hydrogen bonds. When X = Br, compound (V) (C(12)H(8)BrClN(2)O), the molecules are linked into sheets by N-H...O and C-H...N hydrogen bonds, while in compound (VI), where X = I (C(12)H(8)ClIN(2)O), the molecules are linked into a three-dimensional framework by N-H...O and C-H...pi(arene) hydrogen bonds and an iodo...N(pyridyl) interaction. For X = CH(3)O, compound (VII) (C(13)H(11)ClN(2)O(2)), the molecules are linked into chains by a single N-H...O hydrogen bond. Compound (VIII) (C(13)H(8)ClN(3)O, triclinic P1 with Z' = 2), where X = CN, forms a complex three-dimensional framework by N-H...N, C-H...N and C-H...O hydrogen bonds and two independent aromatic pi...pi stacking interactions.

Crystallography, X-Ray↗
PubMed2006

N-(2-Hydroxy-3-iodo-5-nitrobenzylidene)-3-nitroaniline: conformational isomers linked into complex sheets by five C-H...O hydrogen bonds and a two-centre iodo-nitro interaction.

The title compound, C(13)H(8)IN(3)O(5), crystallizes with Z' = 2 in the space group P2(1)/n. The two independent molecules, which are both almost planar, are conformational isomers. The molecules are linked into complex sheets by a combination of five independent C-H...O hydrogen bonds and an almost linear two-centre iodo-nitro interaction.

Journal Article↗
PubMed2006

4-Iodo-N,N-bis(2-nitrophenylsulfonyl)aniline: a three-dimensional framework structure built from six independent C-H...O hydrogen bonds.

In the title compound [systematic name: 4-iodophenylimino bis(2-nitrobenzenesulfinate)], C(18)H(12)IN(3)O(8)S(2), where the molecules do not exhibit even approximate local symmetry, the molecules are linked into a complex three-dimensional structure by six independent C-H...O hydrogen bonds, which utilize O atoms in nitro and sulfonyl groups as the acceptors.

Journal Article↗
PubMed2006

Three substituted (Z)-5-benzylidene-2-thioxothiazolidin-4-ones: hydrogen-bonded dimers that can be effectively isolated or linked into chains either by aromatic pi-pi stacking interactions or by dipolar carbonyl-carbonyl interactions.

In each of the isomeric compounds (Z)-5-(2-fluorobenzylidene)-2-thioxothiazolidin-4-one, C(10)H(6)FNOS(2), (I), and (Z)-5-(4-fluorobenzylidene)-2-thioxothiazolidin-4-one, C(10)H(6)FNOS(2), (II), there is a very wide C-C-C angle (ca 130 degrees ) at the methine C atom linking the two rings. In each isomer, paired N-H...O hydrogen bonds link the molecules into centrosymmetric R(2)(2)(8) dimers; the hydrogen-bonded dimers are linked into chains by an aromatic pi-pi stacking interaction in isomer (I) and by an antiparallel dipolar carbonyl-carbonyl interaction in isomer (II). (Z)-5-(3,4,5-Trimethoxybenzylidene)-2-thioxothiazolidin-4-one, C(13)H(13)NO(4)S(2), (III), which crystallizes with Z' = 2 in the space group P-1, shows the same very wide angle at the bridging methine C atom; the two independent molecules are linked into an isolated dimer having no crystallographic symmetry.

Journal Article↗
PubMed2006

Four 2-aryl-8,8-dimethyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-ones: isolated molecules, hydrogen-bonded dimers, and pi-stacked chains of hydrogen-bonded dimers.

In each of the three compounds 2-(4-chlorophenyl)-5,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one, C19H18ClN3O, (I), 2-(4-methoxyphenyl)-5,8,8-trimethyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one, C20H21N3O2, (II), and 8,8-dimethyl-2-(4-methylphenyl)-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one monohydrate, C19H19N3O.H2O, (IV), the non-aromatic carbocyclic ring adopts a half-chair conformation, while in 2-(4-chlorophenyl)-8,8-dimethyl-5-phenyl-6,7,8,9-tetrahydropyrazolo[2,3-a]quinazolin-6-one, C24H20ClN3O, (III), the corresponding ring adopts a conformation intermediate between the envelope and screw-boat forms. The structure of (I) consists of isolated molecules, while that of (II) contains dimers formed by C-H...O hydrogen bonds. In (III), dimers formed by C-H...O hydrogen bonds are linked into chains by means of an aromatic pi-pi stacking interaction, while in the monohydrate, (IV), the heterocyclic molecules and the water molecules are linked by O-H...O and O-H...N hydrogen bonds to form centrosymmetric four-component aggregates.

Crystallography, X-Ray↗
PubMed2006

2,4-Dinitrophenylhydrazine, redetermined at 120 K: a three-dimensional framework built from N-H...O, N-H...(O)2, N-H...pi(arene) and C-H...O hydrogen bonds.

In the title compound, C6H6N4O4, the bond distances indicate significant bond fixation, consistent with charge-separated polar forms. The molecules are almost planar and there is an intramolecular N-H...O hydrogen bond. The molecules are linked into a complex three-dimensional framework structure by a combination of N-H...O, N-H...(O)2, N-H...pi(arene) and C-H...O hydrogen bonds.

Journal Article↗
PubMed2006

Sheets built from C-H...O and C-H...pi(arene) hydrogen bonds in (2RS,6SR)-N-diphenylacetyl-2,6-diphenylpiperidin-4-one and (2RS,3SR,5RS,6SR)-3,5-dimethyl-N-phenylacetyl-2,6-diphenylpiperidin-4-one.

In (2RS,6SR)-N-diphenylacetyl-2,6-diphenylpiperidin-4-one, C31H27NO2, (I), the piperidinone ring adopts an almost ideal twist-boat conformation, and the molecules are linked into sheets by a combination of one C-H...O hydrogen bond and one C-H...pi(arene) hydrogen bond. (2RS,3SR,5RS,6SR)-3,5-Dimethyl-2,6-diphenyl-N-phenylacetylpiperidin-4-one, C27H27NO2, (II), crystallizes with Z' = 2 in the space group P-1; the piperidinone rings adopt an almost ideal boat conformation in one of the molecules and a conformation between boat and twist-boat in the other. The molecules of (II) are linked into sheets by a combination of five C-H...O hydrogen bonds and one C-H...pi(arene) hydrogen bond.

Carbon↗
PubMed2006

Hydrogen-bonded chains of rings linked by iodo-carbonyl interactions in 5-iodoisatin and hydrogen-bonded sheets in 7-trifluoromethylisatin.

In 5-iodoisatin (5-iodo-1H-indole-2,3-dione), C8H4INO2, the molecules are linked into chains of rings by N-H...O and C-H...O hydrogen bonds, and these chains are linked into sheets by iodo-carbonyl interactions. In 7-trifluoromethylisatin (7-trifluoromethyl-1H-indole-2,3-dione), C9H4F3NO2, the molecules are linked into sheets of centrosymmetric R(2)2(8) and R(6)6(34) rings by N-H...O and C-H...O hydrogen bonds.

Crystallography, X-Ray↗
PubMed2006

A three-dimensional framework of pi-stacked hydrogen-bonded chains in benzyl 4-chloro-3-nitrobenzoate, and chains of hydrogen-bonded rings in benzyl 4-nitrobenzoate, redetermined at 120 K.

Benzyl 4-chloro-3-nitrobenzoate, C14H10ClNO4, crystallizes with Z' = 2 in the space group P-1. The molecules are linked by three independent C-H...O hydrogen bonds into chains of edge-fused R(4)4 (26) and R(4)4 (34) rings, and these chains are linked into a three-dimensional framework structure by aromatic pi-pi stacking interactions. In benzyl 4-nitrobenzoate, C14H11NO4, the molecules are linked by two independent C-H...O hydrogen bonds into chains containing two types of R(2)2 (10) ring.

Benzyl Compounds↗
PubMed2006

Hydrogen-bonded sheets in racemic cis-(2,2'-bipyridyl-kappa2N,N')oxo(pentane-2,4-dionato-kappa2O,O')(thiocyanato-kappaN)vanadium(IV).

The title compound, [V(C5H7O2)(NCS)O(C10H8N2)], crystallizes with Z' = 2 in the space group Pbca. The molecules are linked into sheets by a combination of four C-H...O hydrogen bonds and one C-H...N hydrogen bond. The four C-H...O hydrogen bonds generate chains of rings, where each chain contains just a single enantiomer of each of the two independent molecules, while the C-H...N hydrogen bond generates a chain containing both enantiomers of just one of the independent molecules.

Journal Article↗
PubMed2006

Racemic cis-methoxobis(2-methyl-3-oxo-4H-pyran-4-olato)oxovanadium(V) redetermined at 120 K: hydrogen-bonded ribbons containing R2/2(7), R2/2(14) and R4/4(18) rings.

In the title compound, [V(CH3O)(C6H5O3)2O], the V-O bond lengths to the oxo and methoxo ligands are 1.593 (3) and 1.768 (3) A, respectively, at 120 K; the V-O bond lengths trans to these two ligands are 2.246 (3) and 2.116 (3) A. Molecules are linked by three C-H...O hydrogen bonds into complex ribbons containing three types of ring.

Crystallography, X-Ray↗
PubMed2006

4,5,6-Triamino-2-(methylsulfanyl)pyrimidine: pi-stacked hydrogen-bonded sheets of R2/2(8), R2/2(10) and R6/6(32) rings.

In the title compound, C5H9N5S, the three independent C-NH2 units are all somewhat pyramidal. The molecules are linked by a combination of one N-H...S and two N-H...N hydrogen bonds into sheets containing three types of ring motif, viz. R(2)(2)(8), R(2)(2)(10) and R(6)(6)(32), all of them centrosymmetric. Adjacent sheets are linked by a single pi-pi stacking interaction.

Crystallography, X-Ray↗