Efficient Deep Blue Platinum Acetylide Phosphors with Acyclic Diaminocarbene Ligands

Abstract

Here we report five blue-phosphorescent platinum bis-phenylacetylide complexes with an investigation of their photophysical and electrochemical attributes.T hree of the complexes (1-3)a re of the general formula cis-Pt(CNR) 2 (C CPh) 2 ,i nw hichC NR is av ariably substituted isocyanide and CCPh is phenylacetylide. These isocyanide complexess erve as precursors for complexes of the general formula cis-Pt(CNR)(ADC)(CCPh) 2 (4 and 5), in which ADC is an acyclic diaminocarbene installed by amine nucleophilic addition to one of the isocyanides. All of the complexes exhibitd eep blue phosphorescence with l max~4 30 nm in poly(methyl methacrylate)(PMMA) thin films. Whereas isocyanide complexes 1-3 exhibit modestp hotoluminescence quantum yields(F PL), incorporation of one acyclic diaminocarbene ligandr esults in at hree-fold to 16-fold increasei nF PL while still maintaining an identicaldeep blue color profile.

Tuning the luminescence of transition metal complexes with acyclic diaminocarbene ligands

“…In the solid state and immobilised in the PS matrix 119 Bis-alkynyl species 76 and 77 with ADC ligands were prepared by nucleophilic addition of dimethylamine to the coordinated isocyanide in 74 and 75 (Scheme 10). 120 Despite a large excess of diethylamine and a long time (3 days), addition to a solely coordinated isocyanide occurs. The authors associate the lack of reactivity of the second isocyanide to steric restrictions, which prevent the formation of bis-ADCs.…”

The Search for Efficient True Blue and Deep Blue Emitters: An Overview of Platinum Carbene Acetylide Complexes

“…[b] 10 wt% in PMMA, [c] 1 wt% in PMMA, and [d] 2 wt% in PMMA. [18,35,38] Complex Photophysical Properties PMMA 2-MeTHF, 77 K (glass)…”

“…Cook and co-workers synthesised multinuclear metallacycles and metallacages, achieving multifunctional materials (28) that can be applied as supramolecular sensors and catalysts apart [35,18,2,37,38] from being used as chromophores (Figure4). [2] The building unit of 28 involves a Pt(II) bis-NHC bis-acetylide that exhibits an absorption maximum at 310 nm and two additional bands at 229 and 287 nm.…”

“…Though modifications of the acetylide ligand with extended conjugation, heteroatom, or electron withdrawing substituents has proven successful in obtaining high PLQYs, a delicate balance needs to be achieved in terms of PLQYS and excited-state lifetimes. Highly conjugated molecules (38)(39)(40) redshift the emission, indicating that conjugation is a strategy with limitations. The HOMO and LUMO of such molecules tend to be localised on the acetylide ligand and consequently the effect of the carbene on the excited-state properties are minimised.…”

“…Figure 4. Representative synthesis and structures of cis-bis NHC Pt(II) bisacetylide complexes 18-31 [35,18,2,37,38]. …”