Phosphorescent Platinum(II) Complexes with Mesoionic 1H‐1,2,3‐Triazolylidene Ligands

Abstract

The synthesis and characterization of eight unprecedented phosphorescent C^C* cyclometalated mesoionic aryl-1,2,3-triazolylidene platinum(II) complexes with different β-diketonate ligands are reported. All compounds proved to be strongly emissive at room temperature in poly(methyl methacrylate) films with an emitter concentration of 2 wt %. The observed photoluminescence properties were strongly dependent on the substitution on the aryl system and the β-diketonate ligand. Compared to acetylacetonate, the β-diketonates with aromatic substituents (mesityl and duryl) were found to significantly enhance the quantum yield while simultaneously reducing the emission lifetimes. Characterization was carried out by standard techniques, as well as solid-state structure determination, which confirmed the binding mode of the carbene ligand. DFT calculations, carried out to predict the emission wavelength with maximum intensity, were in excellent agreement with the (later) obtained experimental data.

Luminescent Platinum(IV) Complexes Bearing Cyclometalated 1,2,3‐Triazolylidene and Bi‐ or Terdentate 2,6‐Diarylpyridine Ligands

“…However, most of them are normal 2-imidazolylidene-typea ryl-NHCs, whereas mesoionic aryl-NHCs have only been employed to prepare a limited number of luminescent Pt II complexeso ft he type [Pt(C^C*)(O^O)] (O^O = b-diketonate). [58,59] To the best of our knowledge,P t IV speciesb earing this class of ligand have not been reported to date.…”

“…Cyclometalating aryl‐NHC ligands have previously been employed for the synthesis of luminescent complexes of Ir III , Pt II , and Au III[57] with enhanced emission properties, often as non‐chromophoric supporting ligands. However, most of them are normal 2‐imidazolylidene‐type aryl‐NHCs, whereas mesoionic aryl‐NHCs have only been employed to prepare a limited number of luminescent Pt II complexes of the type [Pt(C^C*)(O^O)] (O^O=β‐diketonate) . To the best of our knowledge, Pt IV species bearing this class of ligand have not been reported to date.…”

Phosphorescent Cyclometalated Platinum(II) aNHC Complexes

“…Here, we present the first examples of C^C* cyclometalated platinum( II ) complexes with bidentate, abnormally bound imidazolinylidene ligands . Following our studies on mesoionic 1,2,3‐triazolylidenes in platinum triplet emitters we extended our research towards the photophysics of platinum aNHC complexes.…”

Metal Complexes of Click-Derived Triazoles and Mesoionic Carbenes: Electron Transfer, Photochemistry, Magnetic Bistability, and Catalysis

“…Apart from complex 120 + , complexes 121 + , 122 , 123 , 124 , and 125 were also reported (Figure ). [88d], [100b], Complex 122 was investigated for photochemical properties, and they were found to be strongly emissive at room temperatures. [108a] The complexes 123 and 124 were obtained from the same reaction mixture, where the starting ligand was a bi‐triazolium salt.…”

“…[88d], [100b], Complex 122 was investigated for photochemical properties, and they were found to be strongly emissive at room temperatures. [108a] The complexes 123 and 124 were obtained from the same reaction mixture, where the starting ligand was a bi‐triazolium salt. Interestingly, an N‐demethylation was observed at one of the triazolium rings leading to the formation of the complex 124 .…”