Synthesis and Photophysics of Liquid-Crystalline Complexes of Gold(III) and Platinum(IV)

Phosphorescent metal complexes are of great potential interest in optoelectronic applications, for example as emitters in organic light emitting diodes (OLEDs), due to the ability of such materials to emit from the triplet excited state. Through the combination of liquid-crystalline properties with triplet emission, these materials can form structures with long-range order that can display increased charge-transport abilities and show polarised emission.

It has been shown that the platinum(IV) complex [Pt(p-tolpy)2Cl2] can be prepared through a microwave-assisted, one-pot procedure. Alkoxyphenyl-functionalised analogues showed lamellar mesophases, which is remarkable given the low level of alkoxy-functionalisation and octahedral metal geometry. All of the platinum(IV) complexes were emissive in solution, showing moderate quantum yields of ≈10% and long lifetimes of up to 230 microseconds.

A large family of liquid-crystalline bis-cyclometallated gold(III) alkynyl complexes of the general formula [Au(C^N^C)(C≡CR)] has been synthesised, where C^N^C is an alkoxy-functionalised, 2,6-diphenylpyridine ligand and C≡CR is an alkoxy-functionalised phenylalkynyl ligand. These complexes showed varied liquid-crystalline properties, as well as tunable emissive behaviour and impressive OLED device performance.