Synthesis and photophysics of one mononuclear Mn(III) and one dinuclear Mn(III,III) complex covalently linked to a ruthenium(II) tris(bipyridyl) complex

The preparation of donor (D)-photosensitizer (S) arrays, consisting of a manganese complex as D and a ruthenium tris(bipyridyl) complex as S has been pursued. Two new ruthenium complexes containing coordinating sites for one (2a) and two manganese ions (3a) were prepared in order to provide models for the donor side of photosystem II in green plants. The manganese coordinating site consists of bridging and terminal phenolate as well as terminal pyridyl ligands. The corresponding ruthenium-manganese complexes, a manganese monomer 2b and dimer 3b, were obtained. For the dimer 3b, our data suggest that intramolecular electron transfer from manganese to photogenerated ruthenium(III) is fast, k(ET) > 5 x 10(7) s(-)(1).     

The quality of99mTc eluates

The possible effects of several protecting procedures on the quality of^99mTc eluates were investigated. The content of⁹⁹Mo in the eluates (⁹⁹Mo breakthrough) was expressed in (%) with respect to the total adsorbed⁹⁹Mo radioactivity and in () i.e. as the ratio of⁹⁹Mo and^99mTc radioactivities in each particular eluate. The radiochemical purity was expressed in (%) of^99mTc(VII) in the eluates. The content of Al³⁺ and Cu²⁺ as chemical impurities was also determined.     

Synthetic studies on the bryostatins: synthetic routes to analogues containing the tricyclic macrolactone core

[reaction: see text]. Synthesis of the first of a projected series of bryostatin analogues has been accomplished in 26 steps and 2.2% overall yield. In this letter, we detail two approaches to the structural core of these tricyclic macrolactone bryostatin analogues. The key features of the route include BITIP-catalyzed asymmetric allylation reactions and Mukaiyama aldol reactions, a chelation-controlled allylation, pyran annulation reactions, and macrolactonization.     

Cationic polymerization of dienes VII. New electron donors in the polymerization of 1,3-pentadiene initiated by aluminum trichloride in non-polar solvent

The aim of this research was to investigate new bulky electron donors (EDs) generating hindered active species in the cationic polymerization of 1,3-pentadiene initiated by AlCl₃ in pentane, in order to avoid or strongly reduce the reaction between the active species and the double bonds of the polymer which are responsible for side reactions. At room temperature, the polymerization in the presence of new ED, such as OPh₂, N(PhBr)₃, NPh₃ and SPh₂, allowed to obtain higher conversions and lower insoluble fractions than without electron donor. The formation of a complex ED/AlCl₃ was shown for each electron donor. However, in the case of NPh₃ and SPh₂, variations of the polymer microstructure demonstrated an interaction between active species and these EDs. Similar results were obtained at lower temperature (−10 °C). The beneficial effect of the presence of electron donors such as NPh₃ and SPh₂ demonstrated the validity of the concept of sterically hindered active species, but the polymerization was still uncontrolled.     

Mobilities of some positive and negative hydrogen ions in He and H2

Mobilities of H⁺ and H^? in He and in H₂, and of H⁺₂ and H⁺₃ in He, are calculated from ion-neutral potentials derived from theory and ion-beam scattering. Agreement with experiment is reasonable except for H^? in H₂ and H⁺₂ in He, which present unexplained puzzles.     

On the exactness of a theorem of G.A. Fomin

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