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

Abstract

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