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Spacer Group (spacer + group)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Synthesis of Cationic Cholesterol Derivatives with Succinyl Spacer Group.

CHEMINFORM, Issue 18 2003
T. V. Konstantinova
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Single-dose study to compare the pharmacokinetics of HFA flunisolide and CFC flunisolide

JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 2 2002
Arno Nolting
Abstract The hydrofluoroalkane (HFA) formulation of the inhaled corticosteroid flunisolide is a modification of the original chlorofluorocarbon (CFC) formulation. HFA flunisolide replaces CFC with an HFA propellant and uses a built-in spacer in its pressurized metered-dose inhaler. The average HFA flunisolide particle size is 1.2 ,m compared with 3.8 ,m for the CFC formulation. The smaller particle size improves lung targeting, allowing a reduction in the HFA flunisolide dose relative to CFC flunisolide while maintaining comparable efficacy. In a study of 12 healthy men, pharmacokinetic parameters were determined after single doses of 1000 ,g CFC flunisolide delivered without a spacer, 340 ,g HFA flunisolide delivered through a spacer, and 516 ,g HFA flunisolide delivered without a spacer. A standard noncompartmental analysis of the concentration data was performed and mean (±,S.D.) pharmacokinetic values were reported. Peak plasma concentrations (observed Cmax) were similar for the three treatments. Area under the curve up to the time corresponding to the last measurable concentration (AUC0,tlast) was similar for the CFC and HFA flunisolide, plus spacer groups (4.4,±,1.6 ng·h/mL and 5.0,±,4.2 ng·h/mL, respectively); however, AUC0,tlast for the HFA flunisolide without spacer group was comparatively lower than for the CFC group (3.5,±,1.6 ng·h/mL). Observed Cmax and AUC0,tlast for 6,-OH flunisolide, the first-pass metabolite of flunisolide and an indicator of oropharyngeal deposition, were significantly higher in the CFC flunisolide group than in either HFA flunisolide group. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:424,432, 2002 [source]

Copper-mediated radical polymerization on a microcellular monolith surface

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2004
Laurence Moine
Abstract High-capacity microcellular monoliths were prepared by a two-step process, including the synthesis of a bromoester-functionalized scaffold by the copolymerization of a highly concentrated emulsion and an in situ surface polymerization of methyl methacrylate with atom transfer radical polymerization. The influence of various parameters, such as the feed ratio, the concentration of immobilized bromoester groups, and the presence of a spacer group on the poly(methyl methacrylate) loading, was studied. Monoliths with capacities of up to 7 mmol g,1 were obtained. Thermogravimetric analyses, scanning electron microscopy experiments, and mercury intrusion porosimetry measurements were used for the characterization of the final materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1216,1226, 2004 [source]

Effect of an aliphatic spacer group on the adsorption mechanism on the colloidal silver surface of L -proline phosphonodipeptides

JOURNAL OF RAMAN SPECTROSCOPY, Issue 12 2008
Edyta Podstawka
Abstract A comparative study of molecular structures of five L -proline (L -Pro) phosphonodipeptides: L -Pro-NH-C(Me,Me)-PO3H2 (P1), L -Pro-NH-C(Me,iPr)-PO3H2 (P2), L -Pro- L -NH-CH(iBu)-PO3H2 (P3), L -Pro- L -NH-CH(PA)-PO3H2 (P4) and L -Pro- L -NH-CH(BA)-PO3H2 (P5) has been carried out using Raman and absorption infrared techniques of molecular spectroscopy. The interpretation of the obtained spectra has been supported by density functional theory calculations (DFT) at the B3LYP; 6,31 + + G** level using Gaussian 2003 software. The surface-enhanced Raman scattering (SERS) on Ag-sol in aqueous solutions of these phosphonopeptides has also been investigated. The surface geometry of these molecules on a silver colloidal surface has been determined by observing the position and relative intensity changes of the Pro ring, amide, phosphonate and so-called spacer (,R) groups vibrations of the enhanced bands in their SERS spectra. Results show that P4 and P5 adsorb onto the silver as anionic molecules mainly via the amide bond (,1630, ,1533, ,1248, ,800 and ,565 cm,1), Pro ring (,956, ,907 and ,876 cm,1) and carboxylate group (,1395 and ,909 cm,1). Coadsorption of the imine nitrogen atom and PO group with the silver surface, possibly by formation of a weaker interaction with the metal, is also suggested by the enhancement of the bands at 1158 and 1248 cm,1. P1, P2 and P3 show two orientations of their main chain on the silver surface resulting from different interactions of the CCH3, NH and CONH fragments with this surface. Bonding to the Ag surface occurs mainly through the imino atom (1166 cm,1) for P2, while for P1 and P3 it occurs via the methyl group(s) (1194,1208 cm,1). The amide group functionality (CONH) is practically not involved in the adsorption process for P1 and P2, whereas the CsP bonds do assist in the adsorption. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Supramolecular Circular Helicates Formed by Destabilisation of Supramolecular Dimers

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2007
Jacqueline Hamblin Dr.
Abstract The effect of changes in the angles at the connection points of linear/circular helicates is explored as a route to control the nuclearity and architecture of metallo-supramolecular arrays. This effect is probed by changing the geometry of the metal centre used to assemble bis-pyridylimine ligands that contain a 1,3-bis(aminomethyl) benzene spacer group. Tetrahedral metal ions favour linear dimers, whereas octahedral nickel(II) predominantly gives a triangular circular helicate. Five-coordinate copper(II) falls in the middle of these extremes and results in the formation of solvent-dependent mixtures of dimer and trimer. The trinuclear, triangular, circular helicate structures, which result from coordination to copper(II) and nickel(II), are structurally characterised by X-ray crystallography and reveal that the units can aggregate into hexagonal arrays that contain anion-filled tube-like channels in the solid state. [source]