New Coordination Compounds for Photochemical Purposes and Beyond

A general account is given of the synthetic research carried out in the field of coordination chemistry in one group in the Institute of Inorganic Chemistry in Fribourg. With the goal of synthesizing artificial structures, which can function as photochemical molecular devices, several synthetic strategies for multicenter coordination species are mentioned. It is reported, that the molecules, which have been designed to form coordination compounds with predefined chiralities of the central metal, can also be used as ligands in enantioselective catalysis

On the Way towards New Materials: Metal Complexes as Building Blocks

Two related directions of materials research are described: i) The synthesis of photonic materials, based on transition-metal compounds mainly with ruthenium and osmium as the photoactive centers. The devices envisaged are antenna molecules, molecular wires, photon-activated switches, and molecules performing other logical functions. ii) The development of a strategy for the synthesis of complex coordination species suitable for molecular devices, based on modular synthons, where a special emphasis is put on the stereochemical aspect of the fragments employed. This strategy is based on a new family of chiral pyridine and bipyridine ligands that are useful for the construction of inert building blocks, as well as in self-assembly processes leading to highly organized systems

The Bright Future of Stereoselective Synthesis of Coordination Compounds

Transfer of chirality during the build-up of molecules has been applied innumerable times in organic chemistry since the end of the 19th century, when it was introduced in the so-called asymmetric synthesis by E. Fischer. Although analogous reactions were introduced in co-ordination chemistry in its early development, diastereoselective reactions have not been applied in a very systematic way for co-ordination species. The highly versatile co-ordination geometry of metal centres makes the synthesis of a selected stereoisomer in general a formidable task. In the present article an account on new developments in the field is given, focussing on recently synthesized molecules, where natural chiral products are used to create a large number of chiral ligands which predetermine the chirality at metal centres

Stereochemistry of Coordination Compounds. From Alfred Werner to the 21st Century

: As a contribution to the scientific symposium, November 22nd, 2013, commemorating the Nobel Prize awarded to Alfred Werner in 1913, a presentation of the development of stereochemistry of coordination compounds during the past 120 years was given. Stereochemistry was fundamental to Werner's theory of coordination compounds. After Werner's death in 1919, stereochemistry in this field did not progress much further for almost 20 years, but then developed continuously. It was realized that stereochemical features of elements showing coordination numbers larger than four are responsible for an almost unlimited number of stereochemical possibilities, thus opening a molecular world of new structures. In the beginning of the 21st century, interest in the field rose again considerably, mainly due to the potential of stereoselective catalysis, and the self-assembly of supramolecular structures. An end of these developments is not in sight. Here an abbreviated version of the lecture is given. A PowerPoint® file, or a video of the presentation, can be downloaded

Supramolecular Chemistry with Chiral Pyridine-Type Ligands

Chiral pyridine-type ligands are readily available in enantiomerically pure form from enantiopure natural products via a Kröhnke reaction. The ease of synthesis allows numerous variations of the ligands which all display a particular coordination behavior. By these means, it is possible to synthesize 'tunable' series of molecules. Thus, mononuclear, as well as self-assembled polynuclear species can be obtained in enantiopure form. With these ligands, a significant step towards the systematic development of stereoselective synthesis in coordination chemistry was achieved, leading to a class of compounds that hold interest for various kinds of applications