The photo- and electroluminescence properties of a series of novel, heteroleptic, mer-cyclometallated iridium complexes have been fine-tuned from green to blue by changing the substituents on the pyridyl ring of the phenylpyridyl ligand. The X-ray crystal structures of two Ir-based triazolyl complexes are reported.

The crystal structure of a cyanine dye rotaxane shows that the cyclodextrin is tightly threaded round the polymethine bridge of the dye; encapsulation dramatically increases the kinetic chemical stability of the radicals formed on oxidation and reduction of the dye, making it possible to observe the rotaxane radical dication by ESR and UV-vis-NIR spectroscopy.

The preparation of the 3,6-disubstituted dibenzosilole monomers 4, 5 and 10 by two different routes is described; Suzuki copolymerisation afforded poly(9,9-dioctyl-3,6-dibenzosilole) 11 which has a sufficiently high triplet energy (2.55 eV) to function as a host for green electrophosphorescent emitters.