Neutral Pt(II) complexes bearing tridentate dianionic 2,6-bis(1H-1,2,4-triazol-5-yl)pyridine and ancillary alkyl-substituted pyridine ligands have been synthesized and characterized. They show bright green emission, reaching 73% photoluminescence quantum yield in deareated chloroform solution, which can be assigned to a predominantly metal-perturbed ligand-centered phosphorescence. We have followed two strategies to preserve the spectral purity of the monomeric species by varying the substituents on the chromophoric or on the ancillary ligands. However, variations in the substitution patterns only modestly affected the radiative and radiationless deactivation rate constants of the monomers. Photophysical and electrochemical properties have been measured for all the complexes and correlated with calculations using time-dependent density functional theory. The electroluminescence spectra of the brightest, nonaggregating derivative showed a better color purity than that of iridium(III) tris(phenylpyridine), thus proving that aggregation was hindered in a running electroluminescent device.

Pt(II) complexes with one bulky, sterically demanding, tertiary phosphite ancillary ligand and a coordinating chromophore are herein presented. The phosphite ligand, tris(2,4-di-tert-butylphenyl) acts as a bidentate ligand coordinating the platinum ion through the central phosphorus atom and a cyclometalating carbon atom of one of the substituents. The two free phenoxy moieties lie above and below the coordination plane, leading to steric hindrance that avoids aggregation and provides solubility in organic solvents. The other two coordination sites on the central metal ion are occupied by a chromophoric ligand, which is responsible for the energy of the luminescent excited state. This separation of functions, on the two coordinated ligands, allows the use of a wider range of luminophores with good luminescent properties, maintaining the control of the intermolecular interactions with the non-chromophoric ligand. Based on this approach we were able to achieve a bright deep blue emission (λ=444 nm, Φem =0.38) from a complex with a tailored ligand, which was then used for the fabrication of an electroluminescent device. In addition commercially available luminophores were also employed to synthesize green emitters.

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Weder in Substanz noch in Lösung scheinen indigoide Verbindungen wie 1 mit Thioxo‐ anstatt Oxogruppen zu existieren. Die Oxidation leukoindigoider Vorstufen führt in keinem Falle zu 1, sondern in Abhängigkeit von den Heteroatomen X (S, NCH3, NH, O)zu den valenzisomeren 1,2‐Dithiinen 2 oder zu makrocyclischen Bisdisulfiden.magnified image

The (3R*,3′R*) configuration of the title compound, C18H16N2S2, (I), has been unambiguously elucidated by X‐­ray analysis. Mol­ecules of (I) have C2 symmetry to a good approximation and a strongly folded shape. The interplanar angle between the two halves of a mol­ecule is 67.11 (6)°.