Towards a general solid phase approach for the iterative synthesis of conjugated oligomers using a germanium based linker--first solid phase synthesis of an oligo-(triarylamine).

The development of a germanium-based linker system for the solid phase synthesis (SPS) of 3-(n-hexyl)thiophene oligomers and the first SPS of triarylamine oligomers via iterative chain extension is described. The efficiency of the key steps in the oligomer syntheses and their compatibility with the germanium linker are demonstrated by the SPS of bi-[3-(n-hexyl)thiophene] 19 and ter-(triarylamine) 50. The use of a germanium-based linker in combination with appropriately selected silicon-based blocking/protecting groups allows double coupling to drive the key cross coupling steps to completion hence minimising deletion sequences and also allows for traceless and potentially functionalisative cleavage from the resin. The latter feature has yet to be fully explored but towards this end the first ipso-borodegermylation reaction of a 2-germyl-3-(n-hexyl)thiophene is presented.

Artificial Photosynthesis: Mimicking Redox Asymmetry.

Directional light-induced electron transfer takes place in the catenane shown schematically on the right. This catenane is similar to the photosynthetic reaction center: The two chemically identical electron acceptors (rectangles) bound to a ruthenium complex as donor have different reduction potentials because their environments are of different polarity. The electron transfer proceeds preferentially (85 %) to the external acceptor.