Application of a calorimetric method in radiation-induced polymerization—III : Determination of propagation and termination rate constants for n-butyl methacrylate

A study on the polymerization of n-butyl methacrylate has been performed using ⁶⁰COγ-rays. The kinetics were followed by a calorimetric method already used with methyl- and ethyl-methacrylate. In this case also, the rate of polymerization was found to be proportional to (dose rate)${}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ over wide ranges of dose rate and temperature.Rate constants for propagation and termination steps have been determined; the results agree with those for the other monomers and with literature data.     

Poly-[nitrilo-bis(phenylamino)phosphorantriyl]e: Beitrag der PN-Gruppe in der Hauptkette zum molaren Volumen und zur Molrefraktion

Ohne Zusammenfassung     

Ammonium hydrogen squarate–water (3/2)

In the title compound, NH₄⁺·C₄HO₄^?·H₂O, the hydrogen squarate anions and water molecules are arranged to form planes almost parallel to bc. The ammonium cations are located between these planes and cross‐link them in the a direction by means of an extensive network of hydrogen bonds. There are two symmetry‐independent sets of cations and anions. One of the hydrogen squarate anions and one of the ammonium cations are situated on a twofold axis and the H atoms of these moieties are disordered over the symmetry‐related sites.     

Crystallographic and IR spectral study ofcis-bis(creatinine-N)dinitro platinum(II)

Acis-Pt(creat)₂(NO₂)₂ complex was synthesized stereoselectively in a high yield (65%) and characterized by IR spectral and X-ray diffraction analysis. Crystal data: Pt(C₄H₇N₃O)₂(NO₂)₂,M _r=767.55, monoclinic, space groupP2₁/n,a=9.736(1),b=13.433(1),c=12.098(1) Å,=110.55(1)°,V _c=1482(1) ų,Z=2,D _x=3.441 g cm^–3,(MoK)=0.71073 Å,=97.0 cm^–1,F(000)=1504,T=292 K,R=0.026 andR _w=0.028 for 2061 observed reflections with I>2(I). The structure consists of Pt(creat)₂(NO₂)₂ molecules disposed in general positions and joined by N-HO and N-HN hydrogen bonds. The platinum atom has square-planar PtN₄ coordination of twocis disposed pairs of nitro [Pt-N_av 2.023(7) Å] and creatinine [Pt-N(endo)_av 1.991(8) Å] ligands. The creatinine moieties are planar and tilted to the equatorial plane by ~80°.     

Drug-Cyclodextrin Association Constants Determined by Surface Tension and Surface Pressure Measurements

The complexation reaction between the amphiphilic peptide antibiotic polymyxin B and naturally occurring cyclodextrins, used as potential drug carriers, was quantitatively evaluated from surface tension measurements at various drug concentrations. The association constant, Ka, of polymyxin B:beta-cyclodextrin inclusion complex formation of 1:1 stoichiometry was determined from the change in the drug interfacial activity upon the addition of beta-cyclodextrin at the excess solution concentration (10(-3) M). The obtained Ka value is discussed in terms of molecular matching of the host cyclodextrin cavity and the guest drug molecule. Copyright 1999 Academic Press.     

Synthetic resins as designable supports for metal-based chemistry: The issue of their nanomorphology and molecular accessibility

Macromolecular cross-linked ligands containing pyridyl pendant groups are characterized by a combination of inverse steric exclusion chromatography, ESR and NMR spectrometries in water and methanol. On the basis of the relevant results, methanol is seen to be clearly the best swelling agent and it is chosen as medium for Cu^II coordination.