Borierte Chromophore für die nichtlineare Optik und Untersuchungen zur Oligomerisierung borreicher Phosphoramidite für die Anwendung gegen Krebs

Abstract

One part of this thesis was the synthesis of chromophoric compounds, which stands a good chance of being used as materials for nonlinear optics. Based on ammonium-undecahydro-closo-dodecaborate requirements for the synthesis of a target compound could be established. The process leading to this target compound so far could not be achieved due to failure to synthesize one internal compound. The reasons for this failure and several alternatives for the preparation of the internal compound were discussed in detail.Another part of this thesis was the synthesis of building blocks based on mercapto-undecahydro-closo-dodecaborate, which were to be oligomerized using the phosphite-triester approach. A sequence for the use in Boron Neutron Capture Therapy was desirable, which consists of these monomers. Four building blocks based on the double charged dodecaborate thus far unknown in the literature were synthesized and characterized. The use of one boronated building block in a standard sequence and the following cleavage of the oligomer by concentrated ammonia revealed that the new monomer in fact marks a point of cleavage in the sequence. However, the successful coupling of the boronated building block before cleavage of the oligomer was underpinned by UV-VIS-spectroscopic detection of coupling yields. The repetition of the experiment under milder cleavage conditions should led to higher mass numbers than before. Therefore investigation in cleavage conditions was expanded systemati-cally. The best results in a comparative study were achieved with ethanolamine (Polushin et al., 1994). The detected values from MALDI-TOF were very close (M 11) to that of the calculated mass of the oligomer. An important disadvantage seemed to be a decomposition of the oligomer, because an unusually high number of signals could be found. Because of that further alternative methods such as usage of photolabile linkers (Greenberg et al., 1994) have been taken into consideration.