Bøger af Dominique Tobias Thielemann

Novel functionalized rare earth metal clusters and polymers have been prepared, characterized and investigated with respect to various potential applications.The literature known tetra- and pentanuclear rare earth metal hydroxy clusters [Ln4(?3-OH)2(Ph2acac)10] (Ln = Pr, Nd, Sm) and [Ln5(?4-OH)(?3-OH)4(Ph2acac)10] (Ln = Y, Eu) were embedded into different polymer matrices applying the miniemulsion polymerization technique to give cluster-polymer hybrid nanocompounds with narrow size distributions. The polymer matrices involved were composed of polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(lauryl methacrylate) (PLMA) and poly(butyl acrylate-co-methyl methacrylate) (PBA-co-MMA). As a consequence of encapsulation, aqueous dispersions containing the hydrophobic clusters with more than 1000 mg¿L-1 could be prepared. Subsequent optical investigations revealed the retention of the encapsulated clusters¿ photophysical properties in aqueous dispersions. Additionally, a very efficient energy transfer from the ligand and polymeric unit to the Eu3+-ions was observed.Envisioning a functionalization of these pure Ph2acac clusters, the pentanuclear mixed ligated rare earth metal hydroxy clusters [Ln5(?4-OH)(?3-OH)4(??AA)4(Ph2acac)6] (1-6) (Ln = Y: ??AA = D-PhGly (1), L-Pro (2), L-Val (3), L-Trp (4), Ph2Gly (5); Ln = Dy: ??AA = D-PhGly (6)) were reproducibly prepared in gram scale and the corresponding solid state structures were established via single crystal X-ray analysis. Clusters 1-6 display a square pyramidal {Ln5(?4-OH)(?3-OH)4}10+ scaffold, which is coordinatively and electronically saturated by six chelating Ph2acac ligands and four amino acid ligands acting as bridging chelates. The hydrodynamic radius rH of valine cluster 3 was determined via NMR-based PGSE diffusion experiments, revealing the retention of the cluster¿s scaffold upon dissolution. Furthermore, 2D NMR experiments with 3 showed a heteronuclear cross coupling between 89Y and 1H nuclei.