Ketotifen controlled release from cellulose acetate propionate and cellulose acetate butyrate membranes

Abstract Ketotifen was immobilised in cellulose acetate propionate (CAP) membranes and in cellulose acetate butyrate (CAB) membranes. The characteristics of each system were evaluated under a range of experimental conditions. The topography and uniformity of the membranes was assessed using scanning electron microscopy. The release characteristics associated with Ketotifen were monitored spectrophotometrically. The swelling capacity of the membranes was evaluated and attributed to the combined effects of diffusion and of complex dissociation, during swelling. The materials produced were able to provide controlled release of Ketotifen due to their controlled swelling behaviour and adequate release properties. The results showed that the release of Ketotifen from the CAB membranes is higher but the release from the CAP membranes is more uniform

Synthesis and reactivities of the 17 e- complex [ReIIBr4(CO)2]2-: A convenient entry into Rhenium(II) chemistry

The reduction of (Et4N)[ReIIIBr4(CO)2] (1) by 0.5 equiv of tetrakis-dimethylaminoethylene in acetonitrile yields directly the air-stable, 17-electron ReII synthon (Et4N)2[ReIIBr4(CO)2] (2) in nearly quantitative yield. The versatility of 2 as a synthon for ReII chemistry was demonstrated by substitution reactions of [ReIIBr4(CO)2]2− with different mono-, bi-, and tridentate ligands. The resulting ReII complexes form highly crystalline compounds, and the solid state structures of the neutral trans−cis-[ReIIBr2(CO)2(X)n] species (where X = imidazole, pyridine, or phenanthroline) could be determined. All complexes are stable under aerobic conditions, both as solids and in solution, and showed fully reversible one-electron ReII → ReI reductions between ca. −70 and −120 mV. Carbonyl stretching frequencies (νCO) of this new family of ReII complexes are observed in the 1990 cm−1 (A1) and 1830 (Eg) cm−1 regions. With complex 2, a wide variety of fundamental but so far unknown ReII complexes become accessible via facile substitution reactions