Biomedical subjects
Publications and source records attributed to Jeroen van Buijtenen.
Racemic omega-substituted caprolactones can be completely converted into chiral polyesters of remarkable MW and high ee by combining lipase-catalyzed ring-opening polymerization with Ru-catalyzed racemization.
Iterative tandem catalysis is presented as a flexible tool for obtaining chiral macromolecules from racemic or prochiral monomers. Here, we combine lipase-catalyzed ring-opening of omega-substituted lactones with ruthenium-catalyzed racemization. In a two-pot system, enantioenriched oligomers of 6-methyl-epsilon-caprolactone were synthesized, which could not have been obtained by enzymatic ring-opening alone. A one-pot experiment proved highly promising in developing a novel route toward enantiopure polyesters.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was applied to the analysis of Ru(OCOCF(3))(2)(CO)(PPh(3))(2), Ru(OCOC(3)F(7))(2)(CO)(PPh(3))(2), Ir(tBuppy)(3) and Ir(ppy)(2)(acac) complexes. A troublesome problem in the MALDI-TOFMS characterization of these metal complexes is the possible replacement of complex ligands by matrix. In this contribution, 10 matrices, ranging from acidic to basic, were investigated: alpha-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (DHB), sinapinic acid (SA), dithranol, 2,4,6-trihydroxyactophenone (THAP), 6-azo-2-thiothymine (ATT), norharman, 2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile (DCTB), 4-nitroaniline (NA) and 2-amino-5-nitrophyridine (ANP). With most of the matrices, including the neutral and basic ones, matrix substitution of ligand could clearly be detected. Based on the experimental results, possible mechanisms of matrix substitution were discussed. It was demonstrated that the ligand exchange process might also occur through the gas-phase reactions initiated by laser shots. Among the matrices tested, DCTB was found to be the best one for the complexes that are prone to ligand exchange by matrix.