| dc.description.abstracteng | Supramolecular structures have become a popular motif in order to design higher order constructs from smaller organic building blocks, which are hold together by non-covalent bonds, such as hydrogen bonds, ion-ion, ion-dipole etc. In combination with metal-ions and organic motifs, which are able to coordinate to those metals, the scope of possible supramolecular structures was even expand. In this work two projects are presented and discussed, dealing with this kind of metal-containing structures, consisting of four bis-monodental organic ligands, capable of coordinating to two metal-ions in a square-planar fashion in order to span up metal-mediated coordination cages. First project deals with the issue of getting an single product (coordination cage), from a mixture of structural related ligands in presence metal ions, without forming a covalent bond between the used ligands. For that reason short oligonucleotide strands (ONS) were attached to both sides of the ligand, complementary to one ONS of the neighboured ligand structure within the targeted supramolecular cage, in order to build up an external oligonucleotide framework which preorganizes the ligands to a defined position, before coordinating to the metal-ion and forming the desired supramolecular cage.
The second project deals with the functionalization of those metal-mediated coordination cages. Some cages have an internal cavity, which can be used as nanoscalic transport container or even reaction vessel, for smaller organic molecules. In order to bring functional groups to the inside of coordination cages, an acridone-based ligand was modified with cyanoacetate derivatives. This system showed an unexpected intramolecular rotational motion, caused by an electronic push-pull system between the electron-withdrawing cyanoacetate motif and the rather electron-rich acridone-nitrogen. This motion could be investigated by various spectroscopic methods, from what also the rotation rate could be derived. The dynamic motion could not only be seen in the ligand, but also in the corresponding metal-mediated coordination cage. Encapsulation of small molecules inside the cages' cavity led to a significant decrease in rotation rate, compared to the empty cage. | de |