Synthesis and light-emitting properties of organic electroluminescent compounds and their metal complexes

Several organic electroluminescent (EL) compounds, 2,2′-(1,4-phenylenedivinylene)bis-3,3-dimethyl-indolenine (1), 2,2′-(1,4-phenylenedivinylene)bis-benzoxazole (2), 2,2′-(1,4-phenylenedivinylene)bis-benzothiazole (3), 4,4′-(1,4-phenylenedivinylene) bis-quinoline (4), 2,2′-(1,4-phenylenedivinylene)bis-quinoline (5), 2,2′-(1,4-phenylenedivinylene) bis-1,3,3-trimethyl-indolenine dichlo ride (6), 2,2′-(1,4-phenylene-divinylene)bis-l-hydro-3, 3-dimethyl-indolenine dichloride (7), 2,2′-(1,4-phenylenedivinylene)bis-8-acetoxyquinoline (8), 2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinoline (9) and metal complexes of 9, Al(PHQ) (10) and Zn(PHQ) (11), have been synthesized and characterized. The crystal structure of 6 was determined. Light emitting properties of the prepared compounds have been investigated. 1 produces an orange-yellow emission (λmax = 575 nm). The cation, 6, gives a red emission (λmax = 607 nm), which is shifted 32 nm to the red compared to 1. 8 produces a yellow emission (λmax = 567 nm). The metal complex 10 gives a red emission (λmax = 610 nm), which is a red shift of 43 nm compared to 8. The change in structure in the prepared compound caused a change in the electron distribution in the compounds, which induces a large wavelength shift of the emitted-light. Thermal analysis showed that the decomposition temperatures of the metal complexes (10, 11) were higher than those for the smaller organic molecular compounds (1–9). Therefore, metal complexes (10, 11) can be used as EL materials over a larger temperature range.