Photochromic diarylethene-containing ionic liquids and N-heterocyclic carbenes.

The design and synthesis of a series of photochromic diarylethene-containing Arduengo-type N-heterocyclic carbenes (NHCs) of gold(I), silver(I) and palladium(II) and their imidazolium salt precursors are reported. Reversible photochromic behavior was observed. The open form and the closed form also show different luminescence properties. The electronic and conformational/steric changes associated with the photocyclization and photocycloreversion reactions may open up new opportunities for the discovery of new classes of photochromic ligands and metal-containing materials and catalysts with photoswitchable functions and activities and regio-/enantioselectivities.