A new nitrogen rich open chain diazine ligand system: synthesis coordination chemistry and magneto-structural studies

Photoluminescence of Platinum(II) Complexes with Diazine-Based Ligands

In the last past twenty years, research on luminescent platinum (II) complexes has been intensively developed for useful application such as organic light emitting diodes (OLEDs). More recently, new photoluminescent complexes based on diazine ligands (pyrimidine, pyrazine, pyridazine, quinazoline and quinoxaline) have been developed in this context. This review will summarize the photophysical properties of most of the phosphorescent diazine Pt(II) complexes described in the literature and compare the results to pyridine analogues whenever possible. Based on the emission color, and the photoluminescence quantum yield (PLQY) values, the relationship between structure modification, and photophysical properties are highlighted. Tuning of emission color, quantum yields in solution and solid state and, for some complexes, aggregation induced emission (AIE) or thermally activated delayed fluorescence (TADF) properties are described. When emitting OLEDs have been built from diazine Pt(II) complexes, the external quantum efficiency (EQE) values and luminance for different emission wavelengths and in some cases, chromaticity coordinates obtained from devices, are given. Finally, this review highlights the growing interest in studies of new luminescent diazine Pt(II) complexes for OLED applications.

N'-(2-Hy-droxy-3-meth-oxy-benzyl-idene)pyrazine-2-carbohydrazide monohydrate

In the title hydrated Schiff base, C13H12N4O3·H2O, the dihedral angle between the aromatic rings is 5.06 (11)° and an intra-molecular O-H⋯N hydrogen bond closes an S(6) ring. In the crystal, Ow-H⋯O and Ow-H⋯N (w = water) hydrogen bonds link the components into centrosymmetric tetra-mers (two Schiff bases and two water mol-ecules). Longer N-H⋯O hydrogen bonds link the tetra-mers into [010] chains. A weak C-H⋯O hydrogen bond and aromatic π-π stacking between the pyrazine and phenyl rings [centroid-centroid separations = 3.604 (2) and 3.715 (2) Å] are also observed.

N′-[1-(Pyrazin-2-yl)ethylidene]pyrazine-2-carbohydrazide

The title compoud, C11H10N6O, was synthesized by the condensation reaction of pyrazine-2-carbohydrazide with 2-acetylpyrazine in ethanol. The dihedral angle between the pyrazine rings is 4.7 (3)°. In the crystal, aromatic π–π stacking [centroid–centroid separations = 3.606 (5) and 3.671 (5) Å] connect the molecules into stacks propagating in the [010] direction. A weak C—H...N interaction is also observed. The crystal studied was refined as a two-component twin.