Rigidification-Induced Emissive Metal-Carbene Complexes for Artificial Light Harvesting.

A tetraphenylethylene (TPE)-based flexible imidazolium ( L ) salt was used to develop a di-nuclear silver(I)-tetracarbene ( 1 ) complex. Coordination-induced rigidity upon formation of 1 exhibited a 6-fold increase in emission intensity in acetonitrile compared to starting L . Despite TPE being a well-known aggregation-induced emissive moiety, Ag I - N -heterocyclic carbene (NHC) complex 1 had a remarkably higher fluorescence emission (4-fold) in dilute solution when compared with L in its aggregated state. Finally, this enhanced emission was used to institute a new platform for an artificial light-harvesting system. 1 acted as an energy donor and efficiently transferred energy to Eosin Y ( ESY ) with a high saturation at a 67:1 ( 1/ESY ) molar ratio. Use of rigidification-induced emission of the Ag I -NHC complex to fabricate a light-harvesting scaffold is a new approach and can greatly impact the generation of smart materials.