Biomedical subjects

L J Fitzgerald

Publications and source records attributed to L J Fitzgerald.

29 records · Page 2Linked to original sources

PubMed1993

Structure of dibenzofuran-d8, C12D8O, at 173 K.

Crystalline dibenzofuran-d8 has been found to exhibit disorder of the type described previously for dibenzofuran. The disordered molecules are related to the ordered molecules by a 180 degrees rotation about an axis passing through the molecular center of mass and perpendicular to the furan ring. In the present structure 11(2)% of the molecules were found to adopt this alternate orientation. The molecules are bisected by a mirror plane normal to the furan ring and containing the O atom. The average bond length in the benzenoid ring is 1.392 (10) A. The furan ring and the benzenoid ring are separately planar, but form a dihedral angle of 1.45 (9) degrees with each other.

Benzofurans↗

PubMed1993

Structure of 1,8-bis(hydroxymethyl)naphthalene.

1,8-Naphthalenedimethanol, C12H12O2, M(r) = 188.24, monoclinic, P2(1)/n, a = 8.549(4), b = 4.856(3), c = 22.604(4) A, beta = 94.24(3) degrees, V = 935.8(7) A 3, Z = 4, Dx = 1.34 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.84 cm-1, F(000) = 400, T = 295 K, R = 0.042 for 1455 unique reflections having I > 3 sigma I. In the title structure the exterior angles at ring atoms C(1), C(8) and C(9) deviate significantly from 120 degrees as a result of the steric interactions of the hydroxymethyl substituents. The ten C atoms comprising the naphthalene core have an average deviation of 0.012 (7) A from the best least-squares plane describing the core. The conformation of the title compound is compared to those of other 1,8-disubstituted naphthalenes. Each hydroxy group is involved in hydrogen bonding as both acceptor and donor, creating infinite chains that propagate in the [010] directions. The neutron-adjusted parameters for the two H...O(acceptor) distances are 1.78 (3) and 1.80 (3) A and for the two O--H...O(acceptor) angles are 165 (2) and 170 (2) degrees. The packing arrangement can be described as a modified herringbone structure with the shortest crystallographic axis coinciding with the b axis of the standard monoclinic setting.

Molecular Structure↗

PubMed1992

Structure of 2,3-naphthalenedicarboxylic acid.

C12H8O4, M(r) = 216.20, monoclinic, C2/c, a = 5.087 (2), b = 19.222 (3), c = 9.552 (2) A, beta = 93.81 (3) degrees, V = 932.0 (5) A3, Z = 4, Dx = 1.54 g cm-3, lambda = 0.71073 A, mu = 1.09 cm-1, F(000) = 488, T = 295 K, R = 0.037 for 687 unique reflections having I > 3 sigma (I). In the structure reported here, a twofold axis lies in the plane of the molecule and bisects the three central ring bonds. The average C--C bond distance in the naphthalene core is 1.401 (27) A and the average interior angle 120.0 (14) degrees. The average deviation of the C atoms comprising the naphthalene rings from the best least-squares plane describing the rings is 0.021 (8) A. The plane of the single unique carboxylic acid group makes a dihedral angle of 33.1 (1) degrees with the least-squares plane of the naphthalene core. The carboxylic acid group, in which the observed O--H distance is 1.00 (3) A, forms a cyclic-dimer hydrogen bond across a center of inversion with the H...O(acceptor) distance 1.68 (3) A, the O...O-(acceptor) distance 2.676 (2) A and the O--H...O-(acceptor) angle 174 (3) degrees. The C--O bond lengths indicate no disorder in the carboxylic acid dimers. The molecules are arranged in stacks with the naphthalene cores parallel to the (102) plane and with the hydrogen bonds of the acid groups linking adjacent stacks. This structure of 2,3-naphthalenedicarboxylic acid is essentially the same as that of o-phthalic acid, but with the b cell edge correspondingly larger to accommodate the additional aromatic ring.

Chemical Phenomena↗

PubMed1992

Structure of tetralithium 1,4,5,8-naphthalenetetracarboxylate dodecahydrate.

4Li+.C14H4O8(4-).12H2O, M(r) = 544.18, triclinic, P1, a = 9.608 (2), b = 10.034 (2), c = 7.033 (1) A, alpha = 94.29 (1), beta = 96.95 (1), gamma = 64.52 (1) degree, V = 607.4 (2) A3, Z = 1, D chi = 1.49 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.29 cm-1, T = 295 K, F(000) = 284, R = 0.039 for 2781 unique reflections having I greater than sigma I. The two inequivalent carboxyl groups adopt a non-planar arrangement with respect to the naphthalene core, making dihedral angles of 52.7 (1) and 54.6 (1) degree with it. The Li+ ions are tetrahedrally coordinated by carboxyl and water O atoms. The Li-O distances are in the range 1.906 (3)-2.041 (3) A, averaging 1.97 (4) A; O-Li-O angles are 101.5 (1)-123.9 (1) degree, averaging 109 (6) degrees. Each of the 12 inequivalent water H atoms is involved in hydrogen bonding. Of these bonds, 11 are typical two-centered hydrogen bonds with an average H...O (acceptor) distance of 1.92 (11) A and an average O-H...O (acceptor) angle of 172 (5) degrees. One water H atom is involved in a three-centered hydrogen bond with an average H...O (acceptor) distance of 2.61 (4) A and an average O-H...O (acceptor) angle of 120 (3) degrees. Adjacent organic anions are separated by the Li+ ions and their coordination polyhedra, with the water molecules occupying positions above and below the naphthalene rings and participating in a three-dimensional hydrogen-bonded network.

Crystallization↗

PubMed1992

1,2-Naphthalenedicarboxylic acid: structures of channel clathrates and an unsolvated crystalline phase.

(1) 1,2-Naphthalenedicarboxylic acid-diethyl ether, C12H8O4.nC4H10O, M(r) = 216.19, tetragonal, I4(1)/a, a = 22.086 (3), c = 9.463 (3) A, V = 4616 (2) A3, Z = 16, F(000) = 1792 (without ether), F(000) = 1873 (with 2.7 molecules of ether per unit cell), Dx = 1.24 g cm-3 (without ether), Dx = 1.31 g cm-3 (with 2.7 molecules of ether per unit cell), lambda(Mo K alpha) = 0.71073 A, T = 296 K, mu = 0.88 cm-1, R = 0.052 for 1130 unique reflections having I greater than 3 sigma I. (2) 1,2-Naphthalenedicarboxylic acid, C12H8O4, M(r) = 216.19, triclinic, P1, a = 9.027 (1), b = 9.234 (1), c = 7.256 (1) A, alpha = 106.08 (1), beta = 90.79 (1), gamma = 111.80 (1) degrees, V = 535.0 (1) A3, Z = 2, F(000) = 224, Dx = 1.34 g cm-3, lambda (Mo K alpha) = 0.71073 A, T = 296 K, mu = 0.95 cm-1, R = 0.043 for 1216 unique reflections having I greater than 3 sigma I. (3) 1,2-Naphthalenedicarboxylic acid-dimethoxyethane, C12H8O4.nC4H10O2, M(r) = 216.19, tetragonal, I4(1)/a, a = 22.067 (2), c = 9.465 (2) A, V = 4609 (1) A3, Z = 16, Dx = 1.25 g cm-3 (without dimethoxyethane), Dx = 1.39 g cm-3 (with 4.4 molecules of dimethoxyethane per unit cell), lambda(Mo K alpha) = 0.71073 A, T = 296 K.(ABSTRACT TRUNCATED AT 250 WORDS)

Clathrin↗

PubMed1992

Structure of the sodium salt of 1,4,5,8-naphthalenetetracarboxylic acid 4,5-anhydride hydrate.

Sodium hydrogen 1,3-dioxo-1H,3H-naphtho[1,8-cd]pyran-6,7-dicarboxylate hydrate, Na[C14H5O7].H2O, Mr = 326.2, triclinic, P1, a = 9.520 (2), b = 9.549 (3), c = 7.860 (1) A, alpha = 105.88 (2), beta = 110.29 (1), gamma = 100.89 (2) degrees, V = 611.9 (3) A3, Z = 2, Dx = 1.77 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.67 cm-1, F(000) = 332, T = 295 K, R = 0.042 for 1665 unique reflections having I greater than 3 sigma I. The organic portion of this structure demonstrates near-C2 symmetry with a pseudo-twofold axis coincident with the central C-C naphthalene ring bond. The atoms of the naphthopyran three-ring system deviate by an average of 0.037 (19) A from the best least-squares plane through the three rings. Each of the carboxyl group planes is substantially inclined to the naphthopyran ring plane, the average dihedral angle measuring 62 (1) degree. The Na ion is coordinated by O atoms in a highly distorted octahedral geometry with a mean Na--O distance of 2.49 (12) A. A short hydrogen bond is formed between a carboxylic acid group and a carboxylate anion; the H...O(acceptor) distance is 1.35 (5) A and the O...O(acceptor) distance is 2.475 (3) A. The acid H-atom position is located asymmetrically with respect to the O atoms. The water H atoms are involved in unequal three-centered hydrogen bonds. The molecules are stacked such that the naphthopyran ring portion of the structure is nearly parallel to the ab cell face and the stacks are connected by the hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗

PubMed1991

Structure of tetrasodium 1,4,5,8-naphthalenetetracarboxylate octahydrate.

Na4[C14H4O8].8H2O, Mr = 536.3, monoclinic, P2(1)/n, a = 6.142 (1), b = 8.144 (3), c = 20.527 (4) A, beta = 93.97 (1) degrees, V = 1024.4 (5) A3, Z = 2, Dx = 1.74 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 2.14 cm-1, F(000) = 552 T = 295 K, R = 0.039 for 1769 unique reflections having I greater than sigma I. In this structure, the title compound has an inversion center at the midpoint of the central naphthalene ring bond. The average C-C bond length in the naphthalene core is 1.41 (3) A; the average interior angle is 119.9 (1.0) degrees. The exterior angle at the central naphthalene carbon is 122.7 (3) degrees, significantly smaller than in 1.8-substituted naphthalenes. The two inequivalent carboxyl groups adopt a non-planar arrangement with respect to the naphthalene core, making an average dihedral angle of 53.8 (1) degree with it. The two inequivalent sodium ions have quite different environments. Na(1) is coordinated by six O atoms in a highly distorted octahedral arrangement with an average Na-O distance of 2.44 (10) A. Na(2) is coordinated by five O atoms in a highly distorted trigonal bipyramidal arrangement with an average Na-O distance of 2.36 (3) A. Each of the eight inequivalent water H atoms is involved in a single hydrogen bond. The average H...O (acceptor) distance is 2.00 (5) A, the average O...O (acceptor) distance is 2.85 (5) A and the average O-H...O (acceptor) angle is 165 (8) degrees for these hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Crystallography↗

PubMed1991

Structure of 4-dibenzofurancarboxaldehyde, C13H8O2.

Mr = 196.21, monoclinic, P2(1)/n, a = 6.589 (1), b = 9.784 (2), c = 14.394 (2) A, beta = 95.69 (1) degrees, V = 923.4 (3) A3, Z = 4, Dx = 1.41 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.89 cm-1, F(000) = 408, T = 296 K, R = 0.048 for 964 unique reflections having I greater than 3 sigma I. The average C-C bond length within the benzenoid rings in 4-dibenzofurancarboxaldehyde is 1.388 (9) A; the average interior angle is 120.0 (2.6) degrees. While two of the three rings of 4-dibenzofurancarboxaldehyde are planar, the benzenoid ring to which the carbonyl group is attached is slightly non-planar. The dihedral angle between the two benzenoid rings measures 1.4(1) degrees. The structure is composed of pairs of 4-dibenzofurancarboxaldehyde molecules related by inversion centers. This structure is further characterized by approaches of both the carbonyl and the furan O atoms to ring H atoms with separations which are slightly less than the sum of the relevant van der Waals radii.

Benzofurans↗

PubMed1991

Structure of 1,8-naphthalenedicarboxylic acid (naphthalic acid), C12H8O4: ring geometry and hydrogen-bonding effects.

C12H8O4, Mr = 216.19, orthorhombic, Pbca, a = 15.308 (2), b = 17.926 (2), c = 7.093 (2) A, V = 1946.4 (5) A3, Z = 8, Dx = 1.48 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.05 cm-1, F(000) = 896, T = 296 K, R = 0.043 for 912 unique reflections having I greater than 3 sigma (I). In this structure, 1,8-naphthalenedicarboxylic acid departs significantly from planarity. While the average deviation of carbons from the best least-squares plane for the naphthalene core is 0.055 (4) A, the carboxyl carbons adopt positions +0.403 (4) and -0.350 (4) A from that plane. The carboxyl groups are twisted in the same direction with respect to that plane and make an average dihedral angle of 42.6 (3) degrees with it. The nearly equal lengths of the C--O distances within the carboxyl groups [mean value 1.267 (5) A] indicate almost complete disorder of the H atoms of these groups. Hydrogen bonding occurs in cyclic dimer fashion between two molecules related by a center of inversion. The carboxyl hydrogens appear to be subject to a symmetric double-minimum potential and to be disordered via tunneling; there is no evidence that the carboxyl oxygens are disordered. The mean carboxyl H--O acceptor distance is 1.90 (7) A.

Molecular Conformation↗

PubMed1991

Structure of phenoxathiin (phenothioxin), C12H8OS, at 223 K.

Mr = 200.25, orthorhombic, P2(1)2(1)2(1), a = 7.758(2), b = 20.506(3), c = 5.896(2) A, V = 938.0(4) A3, Z = 4, Dx = 1.42 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 2.88 cm-1, F(000) = 416, T = 223 K, R = 0.044 for 1414 unique reflections having I greater than 3 sigma I. The phenoxathiin molecule is constituted of two very nearly regular planar hexagonal carbocyclic (benzenoid) rings joined to a non-planar heterocyclic ring. The heterocyclic ring geometry is described in terms of two intersecting planes between which the dihedral angle, the molecular fold angle, is 142.3 degrees. The angle at S (C-S-C) is 97.7(1) degrees, while the angle at O (C-O-C) is 117.4(2) degrees. The overall mean C-C distance in the carbocyclic rings is 1.387(7) A. The absence in this structure of the type of disorder previously found in the dibenzofuran structure is readily understandable since eight sets of close approaches involving each molecule were found in the present structure. These close approaches involve S and O atoms as well as H atoms.

Heterocyclic Compounds↗

PubMed1990

The effects of oral isosorbide 5-mononitrate on mortality following acute myocardial infarction: a multicentre study.

We have conducted a randomized, double-blind, placebo-controlled multicentre trial of oral isosorbide 5-mononitrate (ISMN) in 360 patients with suspected acute myocardial infarction. Patients were stratified prior to analysis according to the presence or absence of left ventricular failure on admission. ISMN caused a significant reduction in systolic and diastolic blood pressure during the first 12 h. There was no significant effect on heart rate. Overall mortality was 4.9% in the ISMN group compared with 4.0% in controls at 5 days, and 14.1% compared with 10.5% at 6 months (NS). A non-significant reduction in mortality in the ISMN group with heart failure (ISMN 7.9%, placebo 12.9%, at 5 days) contrasted with a non-significant increase in mortality in patients without heart failure treated with ISMN (ISMN 4.1%, placebo 2.1%, at 5 days). Lignocaine was used in twice as many patients in the ISMN group as in placebo group (P less than 0.01), both with and without heart failure. Diamorphine usage was similar in the ISMN and control groups. Oral ISMN has similar haemodynamic effects to intravenous nitroglycerin, and can be of benefit in acute myocardial infarction with heart failure. However, our results question the use of nitrates in acute myocardial infarction in the absence of heart failure.

Analysis of Variance↗