White Light Emission from Planar Remote Phosphor Based on NHC Cycloplatinated Complexes

We report on the generation of bright white luminescence through solid-state illumination of remote phosphors based on novel cycloplatinated N-heterocyclic carbene (NHC) compounds. Following a stepwise protocol we got the new NHC compound [{Pt(μ-Cl)(C∧C*)}2] (4) (HC∧C*-κC* = 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazol-2-ylidene), which was used together with the related ones 4a (HC∧C*-κC*= 1-(4-cyanophenyl)-3-methyl-1H-imidazol-2-ylidene) and 4b (HC∧C*-κC*= 3-methyl-1-(naphthalen-2-yl)-1H-imidazol-2-ylidene) as starting materials for the synthesis of the new ionic derivatives [Pt(R-C∧C*) (CNR′)2]PF6 (R = −COOEt, R′ = t-Bu (5), Xyl (6); R = −CN, R′ = t-Bu (7), Xyl (8); R∧C = Naph, R′ = t-Bu (9), Xyl (10)). The X-ray structures of 6 and 8–10 have been determined. The photophysical properties of these cationic compounds have been studied and supported by the time-dependent-density functional theory (TD-DFT) calculations. The compounds 5, 8, and 9 have been revealed as the most efficient emitters in the...