Synthesis, structure, photo- and electroluminescent properties of zinc(II) complexes with aminomethylene derivatives of 1-phenyl-3-methyl-4-formylpyrazol-5-one and 3- and 6-aminoquinolines

• Pyrazole-quinoline derived N, O bidentate Schiff base ligands and their complexes.
• XAFS spectroscopy of complexes.
• Photo- and electroluminescent properties of zinc complexes.

Quinolyl-3-pyrazole (I) and quinolyl-6-pyrazole (II) azomethines have been used as precursors to novel zinc complexes (III, IV, correspondingly) that have been synthesized and thoroughly investigated by IR, UV–vis, NMR 1H spectroscopy. The atomic structure of the complexes was determined by quantum-chemical calculations (DFT-optimization of the molecules geometry). The results obtained were compared with quantitative characteristics of the local atomic environment of zinc ions derived from Zn K-edge EXAFS. Theoretical and experimental data on the bond lengths within the metal coordination sites are in a good agreement. Bands in experimental UV–vis spectra have been assigned based on computational results. Photo- and electroluminescent properties of zinc complexes have been investigated. The photoluminescence maximum occurs around λ = 478 nm for both compounds. Prototypes of electroluminescent devices utilizing the complexes as active media were designed and tested. The device with III as the electroluminescent layer shows a luminance of 800 Cd/m2 at 10 V with conversion efficiency of 0.5 Lm/W, whereas the device with IV as the electroluminescent layer demonstrates somewhat lower characteristics, viz., 200 Cd/m2 at 13 V.

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