Benzannulation via the use of 1,2,4-triazines extends aromatic system of cyclometallated Pt(II) complexes to achieve candle light electroluminescence

Unusual Excimer/Dimer Behavior of a Highly Soluble C,N Platinum(II) Complex with a Spiro-Fluorene Motif

“…In such a case, both the oxidation and reduction cycles are irreversible. This behavior is in line with the electrochemical properties of analogous complexes of acac and ppy-like ligands, which also reduce irreversibly . For example, reduction is often reversible in complexes containing a more electron-deficient pyrimidine, but oxidation nearly always remains irreversible, unless the oxidated state is stabilized by the chelating ligand .…”

“…We note that the experimental photoluminescence of 7, λ PL = 514 nm, is visibly red-shifted with respect to that of related complexes, which display λ PL < 500 nm, 13,36 especially in cases where the phenyl unit attached to the pyridine fragment is not connected to the C-coordinating part of the ligand and can rotate freely. 33 In the case of 7, the said phenyl unit is part planarized by the nonconjugating bridge to the C-coordinating fragment. We indeed observe that the noncoordinating third phenyl unit is to a small extent involved in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) at the T 1 -optimized geometry (Figure 5).…”

“…Considering the various types of chelating ligands in platinum­(II) complexes, ,− we have decided to use a phenylpyridine (ppy)-type C,N ligand with the coordination of the central ion completed with acetylacetonate (acac) following our earlier work . Diketone 1 (Scheme ) was previously used to derive pyrazine-type cyclometallating ligands .…”

Luminescent cyclometalated alkynylplatinum(ii) complexes with 1,3-di(pyrimidin-2-yl)benzene ligands: synthesis, electrochemistry, photophysics and computational studies

“…28 Among them, cyclometalated platinum(II) complexes represent an important class of phosphorescent materials due to their interesting coordination geometry and rich photochemical and photophysical properties in solution and in solid state. [29][30][31] Notably, their four-coordinated square-planar structure can accommodate bidentate, tridentate, or tetradentate chelating ligands [32][33][34][35][36][37] and additional ancillary ligands, [38][39][40] which offers considerable options for engineering targeted highly phosphorescent materials. It has been shown that electronic excited states and their relative energies can be improved via modifications the coordinated ligands around the platinum ion.…”

Thermally activated delayed fluorescence in a deep red dinuclear iridium(iii) complex: a hidden mechanism for short luminescence lifetimes

“…7 In order to red-shift the emission to obtain red- and near-infrared (NIR)-emitting metal complexes, organic ligands featuring more extended conjugation are required, but this is typically accompanied by a reduction in metal admixtures, with predominantly ligand-centred character to the lowest excited states. 8,9 The k T r value suffers as a result, 8,10 limiting the luminescence efficiency that is achievable. Recently, it has been discovered that certain dinuclear complexes of platinum( ii ) 11,12 and iridium( iii ) 13 show faster triplet radiative decay, thanks to more efficient mixing of singlet character into the emissive triplet state.…”