Enantiopure cycloplatinated pentahelicenic N-heterocyclic carbenic complexes that display long-lived circularly polarized phosphorescence

Abstract

The preparation of the first enantiopure cycloplatinated complexes bearing a bidentate, helicenic N-heterocyclic carbene and a diketonate ancillary ligand is presented along with their structural and spectroscopic characterization based on...

Circularly polarized phosphorescence with a large dissymmetry factor from a helical platinum(ii) complex

“…[1][2][3] Square planar platinum(II) complexes are widely known for their highly efficient phosphorescent emission, and CPP materials have been created by introducing chiral ligands. [4][5][6][7][8][9][10][11][12][13][14][15][16][17] Several chiral platinum(II) complexes have been reported to show CPP with large dissymmetry factors (g lum = 2DI/I = 2(I L À I R )/(I L + I R )) 18 in the aggregated state. 7,8,12,16 In particular, the co-assembly of achiral and chiral platinum complexes reported by You and coworkers showed a considerably large g lum value of 0.064 from a magnetically-allowed metal-metal-to-ligand charge transfer (MMLCT) transition.…”

“…Helicenes represent a group of compounds in which aromatic rings are helically fused, and are known to exhibit strong chiroptical properties based on their specific helical chirality. [19][20][21] Furthermore, there have been reports of materials exhibiting highly efficient CPP by introducing helicene ligands into Pt(II), [4][5][6]17 Ir(III), 22,23 Re(I) 24,25 and Au(I) 26 centers. The most successful example was reported by Autschbach, Crassous and coworkers in which a platinum(II) complex with a [6]helicene framework exhibited CPP of the order of 10 À2 in the solutiondispersed state at room temperature.…”