Publikationsserver der RWTH Aachen University
Selbstorganisation von Helicaten und molekularen Tetraedern
Abstract
dc:descriptionIn this research hierarchical multi component self-assembly processes were investigated. The two ligands 2,3-dihydroxybenzaldehyde and 2,3-dihydroxyacetophenone were used for the multistep self-assembly of helicate-type dinuclear titanium(IV) or gallium(III) complexes in the presence of lithium ions. Further more, coordination studies with linear dicatechol diimine ligands, which possess due to the variation of the spacer different geometrical and electronical properties, were made. An enantiomerically pure dinuclear triple-stranded titanium(IV) helicate is formed from a dicatechol diimine ligand with an (R,R)-1,2-diaminocyclohexane spacer and its stereochemical features were elucidated by experimental and theoretical methods. By the complexation of a ligand which possesses C2h symmetry in its idealized structure with titanium(IV), homochiral helicates were diastereoselectively formed. On the other hand a ligand with idealized C2v symmetry leads with surprisingly high selectivity to the formation of the heterochiral meso-helicate. It could be shown, that a rigid connector transfers the stereochemical information of the first complex unit to a stereo-controlling unit, that is located at a distance of about 1 nm from the complex moiety. The small central unit influences the stereochemistry at the second titanium(IV) triscatecholate complex, which again is located 1 nm away. Thus, the stereochemical information is transferred over a distance of nearly 2 nm. Further on, the synthesis of linear ligands with a 2,2’-bipyridine and a dicatechol-unit with different binding sites were described. Thereby the 5,5’-diamino-2,2’-bipyridine was transformed into the imine- or amide-bridged dicatechol-bipyridine ligands. Coordination studies have shown, that it’s possible to selectively choose one of the binding sites by the choice of appropriate metal-ions. A series of triscatechols with an idealized axis of C3-symmetrie were synthesized. Hereby amide, imine or direct bonds are introduced as linkage between the catechol units and various C3-symmetric backbones. Their metal complexes with Ti(IV)ions were investigated. For the first time we succeeded to obtain a molecular tetrahedron with four Ti(IV)ions, which was big enough to bind guests in its interior. It could be shown, that the use of a flexible triscatecholate ligand with a C3-symmetrie leads to a dynamic combinatorial library. The dynamic library of complexes is formed in DMF in the presence of potassium cations. From this library three different coordination compounds can be selected by additi on of an appropriate template, by crystallization, or by equilibration of the mixture in DMSO.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2005
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Janser, Ingo
- Contributors dc:contributor
-
- Albrecht, Markus
Subjects
dc:subject × 9Rights
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:59829