Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.

The antibacterial activities of 31 different b-, mixed a/B-, and y-peptides, as well as of B-peptides derived from B2-3-aza- and B3-2-methylidene-amino acids were assayed against six pathogens (Enterococcus faecails, STaphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa), and the results were compared with literature data. The interaction of these peptides with mammalian cells, as modeled by measuring the hemolysis of human erythrocytes, was also investigated. In addition to those peptides designed to fold into amphiphilic helical conformations with positive charges on one face of the helix, one new peptide with hemolytic activity was detected within the sample set. Moreover, it was demontrated that neither cationic peptides used for membrane translocation (B3-oligoarginines), nor mixeda/B- or y-peptides with somatostatin-mimicking activities display unwanted hemolytic activity.

The solution-phase synthesis of the simplest cyclic B-tetrapeptide, cyclo(B-Ala)4 (4), as well as the solidphase syntheses through side chain anchoring and on-resin cyclization of the cyclic B3-tetrapeptide cyclo-(B3hPhe-B3hLeu-B3hLys-B3hGln-) (14) and the first cyclic B3-pentapeptide cyclo- (B3hVal-B3hPhe-B3Leu- B3hLys-B3hLys-) (19) are reported. Extensive computational as well as spectroscopic studies, including X-ray and NMR spectroscopy, were undertaken to determine the preferred conformations of these unnatural oligomers in solution and in the solid state. cyclo(B-Ala)4 (4) with no chiral side chains is shown to exist as a mixture of rapidly interchanging conformers in solution, whereas inclusion of chiral side chains in the cyclo-B3-tetrapetpride causes stabilizaton of one dominating conformer. The cyclic B3-pentapeptide on the other hand shows larger conformational freedom. The X-ray structure of achiral cyclo(B-Ala)4 (4) displays a Ci-symmetrical 16-membered ring with adjacent C=O and N-H atoms pointing pair wise up and down with respect to the ring plane. CD spectorscopic examinations of all cyclic B-peptides were undertaken and revealed results valuable as starting point for further structural investigations of these entities.

Triorganylsulfonium, -selenonium and -telluronium salts were reduced by carbon dioxide radical anions/solvated electrons produced in aqueous solution by radiolysis. The radical expulsion accompanying reduction occurred with the expected leaving group propensities (benzyl > secondary alkyl> primary alkyl> methy> phenyl), although greater than expected loss of the phenyl group was often observed. Diorganyl chalcogenides formed in the reductions were conveniently isolated by extraction with an organic solvent. Product yields based on the amount of reducing radicals obtained from the y-source were often higher than stoichiometric (up to 1800%) in the reduction of selenonium an dtelluronium compounds; it is likely that this result can be accounted for in terms of a chain reaction with carbon-centred radicals/formate serving as the chain transfer agent. The product distribution was essentially independent of the reducing species for diphenyl alkyl telluronium salts, whereas significant variations were seen for some of the corresponding selenonium salts. This would suggest the intermediacy of telluranyl radicals in the one-electron reduction of telluronium salts. However, pulse radiolysis experiments indicated that the lifetimes of such a species (the triphenyltelluranyl radical) would have to be less than 1 us.

A convenient and high yielding method for the preparation of (R)-tolterodine, utilizing a catalytic asymmetric Me-CBS reduction was developed. Highly enantioenriched (R)-6-methyl-4-phenyl-3,4-dihydrochromen-2-one (94% ee) was recrystallized to yield practically enantiopure material (ee >99%) and converted to (R)-tolterodine in a four-step procedure. The configuration of the crucial stereocenter was preserved during the synthesis and the obtained product was identified by chiral HPLC to be the (R)-tolterodine enantiomer.

Three pyridine-substituted fullerene adducts, bis(2,2'-bipyridine)(2'-phenyl-5'-(2-pyridinyl)-2'H-[5.6]fullereno(C60-Ih)[1,9]pyrazole)ruthenium-bis-(hexafluorphosphate) (1), bis(2,2'-bipyridine)(2'-phenyl-5'-(4-(4'-methyl-2,2'-bipyridinyl)-2'H[5,6]fulleroneo(C60-Ih)[1,9]pyrazole)ruthenium-bis(hexafluorophosphate)(2), and bis(2,2'-bipyridine)(1',5'-dihydro-3'-methyl-2'-(4(4'-methyl-2,2'-bipyridinyl))-2'H-[5,6]fullereno(C60-Ih)[1,9]pyrrole)ruthenium-bis(hexafluorophosphate) 83), have been prepared. The common features for these complexes are the short bridges between he fullerene and the pyridine moities.

An approach to thyroid hormone analogues was proposed involving sequential substitution of cationic cyclopentadienyl(1.4-dichlorobenzene)iron(II) complexes with phenoxide/thiophenoxide and hydroxide/amine, followed by decomplexation. Although the selectivity for monosubstitution with phenolates and thiophenolates was poorer than previously observed, it was often possible to control the reaction with sterically less demanding phenolates of intermediate nucleophilicity. The subsequent introduction of a polar substituent into the monosubstituted product was successful with amine nucleophiles. A modified approach, based on the reverse order of substitution was also attempted. Whereas clean monosubstitution with hydroxide/hydroxide equivalents was unsuccessful, cyclopentadienyl(N-alkyl-1-chloro-4-aminobenzene)iron(II) complexes could be prepared in fair yields and further substituted with nucleophiles such as thiophenolates.

A new type of conjugated polymer, organoselenium substituted poly(p-pheylenevinylene) (PPV), was synthesized from the corresponding alkylselenenyl p-xylylene dibromide via a Gilch route using potassium tert-butoxide in THF. The p-xylylene dibromide precursors were synthesized by reacting lithiated bis(methoxymethyl)benzenes with elemental selenium, followed by alkylation of the generated selenolates. As a final demasking step, the bromomethyl functions were liberated by ether cleavage using boron tribromide. Bis-alkylselenenyl PPV was obtained with an average molecular weight Mw of approximately 300,000 g/mol and with polydispersity Mw/Mn=2. Due to low solubility, monoalkylselenenyl PPV was obtained with a considerably lower average molecular weight in the proximity of 16,000 g/mol and with a polydispersity slightly larger than 3. Absorption and flourescence spectroscopy revealed that the bis-alkylselenenyl PPV is extensively conjugated.

It is known that the relaxed excited state of [Ru(bpy)3]2+ is best described as a metal to ligand charge transfer (MLCT) state having one formally reduced bipyridine and two neutral. Previous reports have suggested [Malone, R. et al. J.Chem. Phys 1991, 95, 8970] that the electron "hops" from ligand to ligand in the MLCT state with a time constant of about 50 ps in acetonitrile. However, we have done transient absorption anisotropy measurements indicating that already after one picosecond the molecule has no memory of which bipyridine was initially photoselected, which suggest an ultrafast interligand randomization of the MLCT state.