Abstract
dc:descriptionIn this dissertation the metal directed self-assembly of tetrahedral complexes of a M4L4 stoechiometry is reported. Several triangular, tritopic, C3-symmetric ligands were prepared and used in the self-assembly process to obtain the metallosupramolecular tetrahedra. These ligands contain three subunits: core, linker/spacer and endunit. In order to prepare ligands and metallosupramolecular terahedra with the best properties, all of these subunits were modified. A chiral group could be attached at the end units and lead to a chiral ligand, which form diastereoselective metallosupramolecular tetrahedra. This was the first example of a successful control of the chirality of metallosupramolecular tetrahedra by chiral, triangular ligands. All other examples based on the usage of linear ligands or the separation of the diastereomers by racemic resolution. Indeed all of these known systems possess only small internal cavities which can’t incorporate more than two guest molecules. The described chiral metallosupramolecular tetrahedra can obtain up to four guest molecules and offer up to now, to the best of our knowledge, the biggest, chiral cavity of this class of compounds. Furthermore the modification of the linker/spacer was of additionally interest. Its composition can strongly influence the properties of the ligands. A chiral linker/spacer could lead to the diastereoselective formation of metallosupramolecular tetrahedra. Pure alkylic linker/spacer improves the solubility of the ligands. Therefore different chiral, alkylic linker/spacer were introduced, but the desired metallosupramolecular tetrahedra could not be prepared. Instead mononuclear complexes were obtained. Some of these complexes which were prepared by chiral TRENcim-ligands contain three protons inside their internal cavity/cap. The presences of the protons compensate partly the charge of the complexes and therefore the structure of these complexes could be better described by two mesomeric structures: 1. The protonated imine structure; 2. The enamine structure. In several experiments it could be observed that the cavity of the nonprotonated species is highly basic. The sodium-containing complexes Na[Na(lig)Ti] are for example able to deprotonate alcohols. The formation of similar protonated species with ditopic ligands and monotopic ligands could be observed, too. Besides these TRENcim-ligands another ligand which contains alkyl chains and ether groups at its linker/spacer was prepared. This ligand forms to mononuclear complexes which cavity/cap shows a strong affinity and selectivity for a cesium cation. At the same time other ligands which contain a rigid aromatic linker/spacer and an imine group were prepared and successfully used to prepare metallosupramolecular terahedra. But all of this complexes are bad soluble and instable against hydrolysis. To improve the properties of the metallosupramolecular tetrahedra pure carbon bridged C3-symmetric ligands were prepared, which contain a mixed aromatic and alkylic linker/spacer. These ligands are good soluble in water and methanol and very stable against external influences. They can be successfully used in the self-assembly of metallosupramolecular tetrahedra and transfer their properties to the complexes. The obtained metallosupramolecular tetrahedra should be useful in host-guest chemistry or as supramolecular reaction vessels. Thanks to the modular concept of synthesis all concepts should be easy to combine and therefore a wide varity of different metallosupramolecular tetrahedra should be available. Additionally the properties could be finetuned. It could be possible to prepare soluble, chiral container via self-assembly which could offer enzyme like abilities.
Degree
thesis:*- Grantor dc:publisher
- Mainz
- Year dc:date
- 2007
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Burk, Simon
- Contributors dc:contributor
-
- Albrecht, Markus
Subjects
dc:subject × 18Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger
Identifiers
dc:identifier.*- OAI identifier oai:identifier
- oai:publications.rwth-aachen.de:62554