title: Enlarging the π system of phosphorescent (C^C*) cyclometalated platinum(II) NHC complexes.
abstract: Cyclometalated (C^C*) platinum(II) N-heterocyclic carbene (NHC) complexes are emerging as a new class of phosphorescent emitters for the application in organic light-emitting devices (OLEDs). We present the synthesis of six new complexes of this class to investigate the influence of extended π systems. Therefore, six different NHC ligands with a varying number of additional phenyl substituents were used in combination with the monoanionic acetylacetonate (acac) ligand to obtain complexes of the general formula [(NHC)Pt(II)(acac)]. The complexes were fully characterized by standard techniques and advanced spectroscopic methods ((195)Pt NMR). For all complexes the solid-state structure determination revealed a square-planar coordination of the platinum atom. Absorption and emission spectra were measured in thin amorphous poly(methyl methacrylate) films at room temperature. Four compounds emit in the blue-green region of the visible spectrum with quantum yields of up to 81%.
authors.affiliation: Physikalische Organische Chemie, Technische Universität Dresden , 01069 Dresden, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tronnier
authors.forename: Alexander
authors.initials: A
authors.lastname: Pöthig
authors.forename: Stefan
authors.initials: S
authors.lastname: Metz
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wagenblast
authors.forename: Ingo
authors.initials: I
authors.lastname: Münster
authors.forename: Thomas
authors.initials: T
authors.lastname: Strassner