Structural studies of analgesics and their interactions. VII. Stereoisomerism and disorder in the structure of oxyphenbutazone monohydrate

Oxyphenbutazone, C19H20N203, a metabolite and perhaps the active form of phenylbutazone, is a widely used non-narcotic analgesic and anti-inflammatory pyrazolidinedione derivative. The monohydrate of the compound crystallizes in the triclinic space group Pi with two molecules in a unit cell of dimensions a -- 9.491 (4), b = 10.261 (5), c = 11.036 (3)A and ¢~ = 72.2 (1), fl = 64.3 (1), 7 = 73.0 (1) °. The structure was solved by direct methods and refined to an R value of 0.107 for 1498 observed reflections. The butyl group in the molecule is disordered. The hydroxyl group occupies two sites with unequal occupancies. On account of the asymmetry at the two N atoms and one of the C atoms in the central five-membered ring, the molecule can exist in eight isomeric states, of which four are sterically unfavourable. The disorder in the position of the hydroxyl group can be readily explained on the basis of the existence, with unequal abundances, of all four sterically favourable isomers.The bond lengths and angles in the molecule are similar to those in phenylbutazone. The crystal structure is stabilized by van der Waals interactions, and O-H... O hydrogen bonds involving the carbonyl and the hydroxyl groups as well as a water molecule.

Hydrophobic channels in crystals of an alpha-aminoisobutyric acid pentapeptide

The crystal structure of the pentapeptide p-toluene-sulfonyl-(α-aminoisobutyryl)5-methyl ester (Tosyl-(Aib)5-OMe) has been determined in the space group PImage . Pentapeptide molecules are folded in the 310 helical conformation and packed together, so as to yield a hydrophobic channel with a minimim diameter of 5.2 �. The channel contains crystallographically disordered material. This structure provides a model for channel formation by hydrophobic peptide aggregates and should prove useful in studies of alamethicin, suzukacillin and related Aib containing membrane channels. Triclinic (PImage ) crystals of the pentapeptide are obtained in the presence of LiClO4 in aqueous methanol, whereas crystallization from methanol alone yields crystals in the space group Pbca. The conformations of the peptide in the two crystal forms are very similar and only the molecular packing is dramatically different.

Magnetic interactions in the oxide systems LaNi1-xMxO3 (M = Cr, Fe, or Co)

Magnetic susceptibilities of several members of the series of oxides of the general formula LaNi1-xMxO3 (M = Cr, Fe, or Co) are reported. The oxides show evidence for interesting ferrimagnetic (Cr and Co) and antiferromagnetic (Fe) interactions.

Stability and structural transitions of tomato aspermy virus and cucumber mosaic virus

The properties of the S-strain of cucumber mosaic virus (S-CMV) and the B-strain of tomato aspermy virus (B-TAV) have been studied with respect to their (i) size and sedimentation behavior, (ii) requirement of divalent metal ions for stability, (iii) sensitivity towards chloride salts and the anionic detergent sodium dodecyl sulfate, (iv) solubility in ammonium sulfate-containing buffers, and (v) pH-dependent structural transitions. The results indicate that the coat protein of B-TAV is more hydrophobic than the other well-studied strains of TAV and CMV. Circular dichroism and uv absorption studies reveal pH-dependent structural transitions, although these do not result in particle swelling. These transitions appear to alter the strength of protein-nucleic acid interactions in these viruses.

Interactions between Mast Cells, Fibroblasts and Connective Tissue Components

It has long been recognized that mast cells occur throughout connective tissues. Histologic studies have revealed that such cells release their granules into the surrounding environment upon exposure to both immunologic and nonimmunologic stimuli. By microscopy these extracellular granules appeared to be phagocytosed by fibroblasts and by blood-borne phagocytic cells as they entered the site of mast cell degranulation. Such in vivo observations led to the suggestion that mast cells both altered connective tissue components and influenced fibroblast function through these discharged granules. Recent in vitro studies using cultured fibroblasts and isolated mast cells and mast cell granules have confirmed both these hypotheses. In addition, such studies have also documented that fibroblasts degrade ingested mast cell granules. Such studies document that a number of critical interactions may occur between mast cells and connective tissue components.

Intermolecular interactions in the formation of aromatic hydrocarbon dimers

Both short-range and long-range intermolecular interaction energies between two aromatic hydrocarbon molecules, both in their ground state, separated by a range of interplanar distances of 3 ∼ 4 Aring, are estimated using the standard perturbation theory. The results show that aromatic hydrocarbons can form weak sandwich dimers with larger separation between them than is normally believed in their excimers. The non-sandwich form of dimer in which the long in-plane axes of the monomers are parallel and their short in-plane axes inclined, represents an unstable orientation because this form can pass to the perfect sandwich form without an energy barrier.

Structural Studies of Analgesics and Their Interactions. VIII.* Rotational Isomerism and Disorder in the Crystal Structure of Meelofenamie Acid

Meclofenamic acid, C I4HIICI2NO2, probably the most potent among analgesic fenamates, crystallizes in the triclinic space group P1, with a = 8.569 (5), b = 8.954(8), c -- 9.371 (4) A, ct = 103.0 (2), fl -- 103.5 (2), y = 92.4 (2) ° , Z = 2, D m = 1.43 (4), D c = 1.41 Mg m -3. The structure was solved by direct methods and refined to R = 0.135 for 1062 observed reflections. The anthranilic acid moiety in the molecule is nearly planar and is nearly perpendicular to the 2,6-dichloro-3-methylphenyl group. The molecules, which exist as hydrogen-bonded dimers, have an internal hydrogen bond involving the imino and the carboxyl groups. The methyl group is disordered and occupies two positions with unequal occupancies. The disorder can be satisfactorily explained in terms of the rotational isomerism of the 2,6-dichloro-3-methylphenyl group about the bond which connects it to the anthranilic acid moiety and the observed occupancies on the basis of packing considerations.

Interactions of aromatic mannosyl disulfide derivatives with Concanavalin A: synthesis, thermodynamic and NMR spectroscopy studies

α-d-Mannopyranosyl units were attached to an aromatic scaffold through disulfide linkages to obtain mono- to trivalent glycosylated ligands for lectin binding studies. Isothermal titration calorimetric (ITC) measurements indicated that binding affinities of these derivatives to Concanavalin A (Con A) were comparable to or slightly higher than that of methyl α-d-mannopyranoside (Ka values in the range of 104 M−1). The stoichiometries of the lectin-ligand complexes were in agreement with the formal valencies (1–3) of the respective ligands indicating cross-linking in interactions with the di- and trivalent derivatives. Multivalency effects could not, however, be observed with the latter. These ligands were shown to bind to the carbohydrate binding site of Con A using saturation transfer difference (STD) NMR competition experiments.

Studies on Unsteady Shock Interactions Near a Generic Scramjet Inlet

An experimental and numerical study is presented to show the effect of cowl length and angle on the ramp/cowl shock interaction phenomena fora two-dimensional planar scramjet inlet model. Experiments areconducted in a hypersonic shock tunnel, at Mach 8, at four lengths of owl and three cowl angles. Investigations include schlieren flow Visualization near the cowl region and static pressure and heat transfer rate measurement inside the inlet chamber. Various ramp/cowl shock interaction processes resulted for different cowl configurations have been visualized using a high-speed camera. Edney type-II interference pattern is observed for 131 and 141-mm cowl lengths,whereas it is an Edney type-I interference pattern in case of a 151 mm cowl with all their typical features resulting because of the ramp/cowl shock interaction. Experiments with a cowl configuration other than 0deg show the flow to he established through the inlet because or the reduced contraction ratio. Heat transfer peaks can be observed for the10 and 20-deg cowl cases where flow through the inlet is found to be established. These may serve as the possible locations of fuel injection.

Structural studies of analgesics and their interactions. II. The crystal structure of a 1:1 complex between antipyrine and salicyclic acid (salipyrine)

The complex crystallizes in the space group P21/c with four formula units in a unit cell of dimensions a= 12.747, b= 7.416, c= 17.894 A and/3= 90.2 °. The structure has been solved by the symbolic addition procedure using three-dimensional photographic data and refined to an R value of 0.079 for 2019 observed reflexions. The pyramidal nature of the two hetero nitrogen atoms in the antipyrine molecule is inter:nediate between that observed in free antipyrine and in some of its metal complexes. The molecule is more polar than that in crystals of free antipyrine but less so compared with that in metal complexes. In the salicylic acid molecule, the hydroxyl group forms an internal hydrogen bond with one of the oxygen atoms in the carboxyl group. The association between the salicylic acid and the antipyrine molecules is achieved through an intermolecular hydrogen bond with the other carboxyl oxygen atom in the salicylic acid molecule as the proton donor and the carboxyl oxygen atom of the antipyrine molecule as the acceptor.

Antiferromagnetic spin-wave states in a linear chain with nearest- and next-nearest-neighbour interactions

The spectrum of short-closed chains up to N=12 are studied by exact diagonalization to obtain the spin-wave spectrum of the Hamiltonian H=2J Sigma i=1Nsi.si+1+2J alpha Sigma i=1Nsi.si+2, -1.0or=0.3 and alpha

Structural studies of analgesics and their interactions. III. The crystal and molecular structure of amidopyrine

Amidopyrine (1-phenyl-2,3-dimethyl-4-dimethylaminopyrazolone), C13HzvN30, a dimethylamino derivative of antipyrine and an important analgesic and antipyretic agent, crystallizes in the triclinic space group P1 with four molecules in a unit cell of dimensions a= 7.458 (5), b = 10.744 (5), c= 17.486 (15)/~,, e=98.6 (2),/~= 85.6 (3), y= 108-6 (2) . The structure was solved by direct methods and refined to an R value of 0.055 for 3706 photographically observed reflexions. The dimensions of the two crystallographically independent molecules are very nearly the same. The pyrazolone moiety in the molecule has dimensions comparable to those in antipyrine. Unlike antipyrine, the molecular dimensions of amidopyrine in the free state (the present structure) are close to those found in some of its hydrogenbonded complexes. Thus it appears that the presence of the dimethylamino group makes the molecule more resistant to changes in its dimensions resulting from molecular association. An attempt has also been made to correlate the polar nature of the pyrazolone moiety and the hybridization state of the hetero nitrogen atoms in antipyrine, amidopyrine and their complexes.

Use of transverse beam polarization to probe anomalous V V H interactions at a Linear Collider

We investigate use of transverse beam polarization in probing anomalous coupling of a Higgs boson to a pair of vector bosons, at the International Linear Collider (ILC). We consider the most general form of V V H (V = W/Z) vertex consistent with Lorentz invariance and investigate its effects on the process e(+)e(-) -> f (f) over barH, f being a light fermion. Constructing observables with definite C P and naive time reversal ((T) over tilde) transformation properties, we find that transverse beam polarization helps us to improve on the sensitivity of one part of the anomalous Z Z H Coupling that is odd under C P. Even more importantly it provides the possibility of discriminating from each other, two terms in the general Z Z H vertex, both of which are even under C P and (T) over bar. Use of transversebeam polarization when combined with information from unpolarized and linearly polarized beams therefore, allows one to have completely independent probes of all the different parts of a general ZZH vertex.

Long-range Coulomb interactions and nanoscale electronic inhomogeneities in correlated oxides

Electronic, magnetic, or structural inhomogeneities ranging in size from nanoscopic to mesoscopic scales seem endemic and are possibly generic to colossal magnetoresistance manganites and other transition metal oxides. They are hence of great current interest and understanding them is of fundamental importance. We show here that an extension, to include long-range Coulomb interactions, of a quantum two-fluid l-b model proposed recently for manganites [Phys. Rev. Lett. 92, 157203 (2004)] leads to an excellent description of such inhomogeneities. In the l-b model two very different kinds of electronic states, one localized and polaronic (l) and the other extended or broad band (b) coexist. For model parameters appropriate to manganites and even within a simple dynamical mean-field theory (DMFT) framework, it describes many of the unusual phenomena seen in manganites, including colossal magnetoresistance (CMR), qualitatively and quantitatively. However, in the absence of long-ranged Coulomb interaction, a system described by such a model would actually phase separate, into macroscopic regions of l and b electrons, respectively. As we show in this paper, in the presence of Coulomb interactions, the macroscopic phase separation gets suppressed and instead nanometer scale regions of polarons interspersed with band electron puddles appear, constituting a kind of quantum Coulomb glass. We characterize the size scales and distribution of the inhomogeneity using computer simulations. For realistic values of the long-range Coulomb interaction parameter V-0, our results for the thresholds for occupancy of the b states are in agreement with, and hence support, the earlier approach mentioned above based on a configuration averaged DMFT treatment which neglects V-0; but the present work has features that cannot be addressed in the DMFT framework. Our work points to an interplay of strong correlations, long-range Coulomb interaction, and dopant ion disorder, all inevitably present in transition metal oxides as the origin of nanoscale inhomogeneities rather than disorder frustrated phase competition as is generally believed. As regards manganites, it argues against explanations for CMR based on disorder frustrated phase separation and for an intrinsic origin of CMR. Based on this, we argue that the observed micrometer (meso) scale inhomogeneities owe their existence to extrinsic causes, e.g., strain due to cracks and defects. We suggest possible experiments to validate our speculation.