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Paul D Robinson

Publications and source records attributed to Paul D Robinson.

11 recordsLinked to original sources
PubMed2006

A hydrogen-bonded heterodimer of 1-(4-hexyloxyphenyl)pyridin-4(1H)-one with 4-cyanobenzoic acid.

The two components of the title heterodimer, C17H21NO2.C8H5NO2, are linked end-to-end via O-H...O(=C) and C-H...O(=C) hydrogen-bond interactions. Additional lateral C-H...O interactions link the dimers in a side-by-side fashion to produce wide infinite molecular ribbons. Adjacent ribbons are interconnected via pi-pi stacking and C-H...pi(arene) interactions. This structure represents the first evidence of robust hydrogen-bond formation between the moieties of pyridin-4(1H)-one and benzoic acid.

Journal Article↗
PubMed2006

Hydrogen-bonded 1:1 adduct of 1,1'-(p-phenylene)dipyridin-4(1H)-one with terephthalic acid.

Cocrystallization of 1,1'-(p-phenylene)dipyridin-4(1H)-one (4,4'-dpy) and terephthalic acid (tpa) affords the hydrogen-bonded 1:1 title complex, C16H12N2O2.C8H6O4. Both molecules are symmetrically disposed about independent symmetry centers. Strong O-H...O hydrogen bonds between tpa carboxyl groups and 4,4'-dpy carbonyl groups produce one-dimensional zigzag infinite chains. Each chain is linked to four surrounding chains via weak C-H...O interactions, resulting in a three-dimensional molecular framework.

Journal Article↗
PubMed2005

N,N',N''-Tris(p-methoxyphenyl)phosphoric triamide.

The title compound, C(21)H(24)N(3)O(4)P, is a self-complementary hydrogen-bond (HB) building unit, with (P=)O as the primary HB acceptor and N-H as the HB donor. Each of the four crystallographically distinct and nearly parallel molecules of the unit cell has a net dipole moment along the P=O bond direction and all of the dipoles are directed in the same general crystallographic direction. Head-to-tail N-H...O=P double-HB strands stack adjacent molecules into one-dimensional infinite polar columns. Each polar column is a 2(1) helix and all columns are essentially parallel, resulting in polar order throughout the entire crystal.

Journal Article↗
PubMed2004

sp-9-(o-Methylphenyl)fluorene.

While the barriers of rotation of the sp and ap rotamers of 9-(o-methylphenyl)fluorene, C(20)H(16), are sufficiently similar to permit them to equilibrate, both being observed (NMR) in solution, crystallization provides the sp rotamer, (I), exclusively. Although in the sp conformation the intramolecular distance between adjacent C atoms of the phenyl and fluorene rings is small [3.382 (4) A, within 0.02 A of the sum of the van der Waals radii], in the ap conformation the distance between the adjacent o-CH(3) group on the phenyl ring and C atom of the fluorene ring would be much closer, based on that exhibited in the crystalline ap progenitor 9-(o-methylphenyl)-9-fluorenol. The angle between the fluorene and 9-aryl planes of (I) is 75.82 (10) degrees.

Journal Article↗
PubMed2003

ap-9-(o-Methylphenyl)-9-fluorenol, a structure exhibiting several aryl-H...pi(arene) intermolecular interactions.

The title compound, C(20)H(16)O, (I), which crystallized exclusively as its ap rotamer, exhibits several intermolecular aryl-H.pi(arene) interactions, resulting in planar molecular arrays in which each molecule interacts with six adjacent molecules. Surprisingly, there were no O-H.O-H or O-H.pi(arene) interactions within hydrogen-bonding distances. Crystalline (I) melted sharply without molecular decomposition (NMR), but the cooled melt recrystallized only after several hours.

Journal Article↗
PubMed2003

ap-9-(meta-tert-butylphenyl)fluorene.

The title compound, C(23)H(22), (I), crystallizes in an ap conformationThe designations sp (synperiplanar) and ap (antiperiplanar) for these fluorene rotamers are in accordance with Rule E-6.6, IUPAC Tentative Rules, Section E, Fundamental Stereochemistry [J. Org. Chem. (1970), 35, 2861]. and its melt readily recrystallizes on cooling, in contrast to the corresponding 9-fluorenol compound, (II), which is sp and which melts without decomposition and fails to recrystallize over a long period. Both of these differences are ascribed to the intermolecular hydrogen bonding in (II), which is absent in (I) and which leads to distinctly different molecular packing in the two compounds.

Journal Article↗
PubMed2003

The effect of load carriage on movement kinematics and respiratory parameters in children during walking.

The objective of this study was to investigate the influence of different backpack weights on trunk kinematics and respiratory parameters during walking in 10-year-old children. Fifteen boys with a mean age of 10.31 (0.26) years were selected from a primary school to participate in four walking trials on a treadmill: one with a backpack of 0% of body mass, and three whilst carrying backpacks that weighed 10%, 15%, and 20% of the child's body mass. The walking speed was set at 1.1 m s(-1) for 20 min duration. The walking movement was recorded on video and analysed in two dimensions. The breathing frequency, tidal volume, and respiratory muscles activity were measured with a cardiopulmonary system (Oxycon Champion, Jaeger) and a respiratory inductance plethysmograph (TR-601T, Nihon Kohden, Japan). A repeated ANOVA and Pearson correlation analysis were used to examine any significant differences in the measured parameters when comparing the different loads. The results showed a significant positive linear relationship between load weight, trunk inclination angle, and breathing frequency ( P<0.01). Walking for 20 min, carrying a load that weighed 20% of body mass induced a significantly increased trunk inclination angle. A significant increase in ventilation during walking with a backpack of 15% and 20% of bodymass was associated with a more rapid breathing frequency. Walking with a backpack of 10% body mass did not significantly change trunk posture or respiratory parameters. However, the results suggested that walking with a backpack of greater than 10% body mass induced significant changes in trunk posture and respiratory parameters in 10-year-old children.

Abdomen↗
PubMed2002

A zwitterionic viologen disulfonate-hydroquinone charge-transfer crystal: 2,2'-(4,4'-bipyridinium-1,1'-diyl)di(ethanesulfonate)-hydroquinone (1/2).

The structure of the title compound, C(14)H(16)N(2)O(6)S(2).2C(6)H(6)O(2), consists of 2,2'-(4,4'-bipyridinium-1,1'-diyl)di(ethanesulfonate) molecules (with crystallographically imposed twofold symmetry) that are hydrogen bonded to each other, as well as to hydroquinone molecules, in a complex three-dimensional motif. The orange color of the crystals is indicative of the donor-acceptor interaction between the electron-rich hydroquinone pi-donor and the electron-deficient bipyridinium pi-acceptor. The dihedral angle between the bipyridyl planes is 38.31 (11) degrees. The distance from the centroid of one of the hydroquinone molecules to the center of the bipyridinium group is 3.653 (3) A, which is within the range typically observed for molecular complexes exhibiting charge-transfer characteristics.

Journal Article↗
PubMed2002

Single crystal structure determination of a new zirconium N-ethylpyridinium phosphonate: Zr(O(3)PCH(2)CH(2)NC(5)H(5))(F(-))(3).

We describe the structure of a new zirconium N-ethylpyridinium phosphonate, Zr(O(3)PCH(2)CH(2)NC(5)H(5))(F(-))(3), that has been determined by single-crystal X-ray analysis (monoclinic, P2(1)/c (No. 14), a = 12.3634(12) A, b = 9.3090(17) A, c = 9.8077(13) A, beta = 112.819(8) degrees, V = 1040.4(3) A(3), Z = 4). This structure is unlike any other reported zirconium phosphonate. Octahedral coordination about zirconium is completed by three oxygen atoms of three different phosphonate groups and three fluoride ligands. The structure is composed of corrugated infinite layers of these Zr octahedra that corner share their three oxygen atoms with the phosphonate tetrahedra. The appended cationic pyridinium groups lie between the inorganic sheets and are charge-balanced by the [Zr(O(3)P-)(3)F(3)](-) octahedra. This structure represents a new example of the structure-directing influence of cationic organic ligands on the zirconium phosphonate framework.

Journal Article↗
PubMed2002

trans-3-Ethyl-cis-2,6,6-trimethyl-4-oxocyclohexanecarboxylic acid: an intermediate in the synthesis of a highly potent estrogen.

The title compound, C(12)H(20)O(3), (IV), the ethyl ester of which is an intermediate in the synthesis of a compound reported to be highly estrogenic, has been prepared. After the initial steps reported for the synthesis of this ester intermediate were followed, it was converted into the crystalline acid, (IV), for X-ray analysis. It was verified that (IV) was racemic when prepared. X-ray analysis showed that anti-hydrogenation of the double bond had occurred in the synthesis, making the orientation of the carboxyl group cis to the 2-methyl group and trans to the 3-ethyl group. NMR spectroscopy showed that the stereochemistry of (IV) was identical with that of its ester precursor. While the earlier report did not note the stereochemistry of this ester, it pointed out that the estrogenic product derived from it possessed the opposite carboxyl-2-methyl orientation, i.e. trans, although no X-ray analysis was performed. In the light of these results and the importance of correlating biological activity with compound structure, the unequivocal characterization of the highly estrogenic compound is warranted.

Cyclohexanecarboxylic Acids↗