- Stereochemical Effects on Monolayer Formation of (2+) (dpp = 4,7-Diphenyl-1,10-phenanthroline) at an Air-Water Interface
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Stereochemical effects on monolayer formations have been studied at an air-water interface for the racemic mixture and enantiomer of (ClO4)2 (dpp = 4,7-diphenyl-1,10-phenanthroline).Stearic acid (SA) was added to reduce the cohesive interaction of the Ru(II) complexes.The ration of SA to Ru(II) complex, /, was varied from 0 to 4.At / = 0 and 1, the lift-off area per molecule at which the surface pressure increased from zero was smaller for the racemic mixture than for the enantiomer.The results indicated that the racemic mixture of the Ru(II) complex formed a more compact monolayer than the enantiomer.There was no difference observed in the surface pressure-molecular area (?-A) curves at / larger than 3.The monolayer was transferred onto a hydrophobic glass or silicon wafer substrate as a Langmuir-Blodgett (LB) film of Y-type.At / = 1, the d(001) spacing of the film was determined by X-ray diffraction measurements, leading to d(001) = 50.4 and 37.8 Angstroem for the racemic mixture and the enantiomer, respectively.The IR reflection-adsorption spectroscopy showed that the alkyl chains of SA molecules took different orientations for the racemic and enantiomeric films.It is postulated that SA molecules which intervened between the Ru(II) complexes are more perpendicular to the substrate surface due to the closer packing of the racemic Ru(II) complexes than the enantiomers.
- Yamagishi, Akihiko,Goto, Yasutomo,Taniguchi, Masahiro
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- Ruthenium(II) Complex as Phosphorescent Dopant for Highly Efficient Red Polymers Light-Emitting Diodes
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Red electrophosphorescence from light-emitting devices based on a ruthenium(II) complex [Ru(4,7-Ph2-phen)3] 2+-doped wide-band-gap semiconductive polymers, e.g., poly(vinylcarbazole) (PVK), polydihexyl-fluorene (PF), and ladder-like polyphenylene (LPPP), as the emitting layer are reported. These polymers show the short-wavelength electroluminescence emission peaking ranged from 410 to 490 nm, which overlaps well with the absorption band of [Ru(4,7-Ph 2-phen)3]2+; however, very efficient energy transfer was investigated in the PVK system, likely due to relative long excited-state lifetimes of PVK than that of PF and LPPP and good chemical compatibility of [Ru(4,7-Ph2-phen)3]2+ with PVK. The EL spectra show the characteristic spectrum of [Ru(4,7-Ph 2-phen)3]2+, with a peak at 612 nm and CIE of (0.62, 0.37) which is comparable with standard red color. The optimized device ITO/PVK 5 wt % [Ru(4,7-Ph2-phen)3]2+/PBD/ Alq3/LiF/Al shows the maximum luminance efficiency and power efficiency of 8.6 cd/A and 2.1 lm/W, respectively.
- Xia, Hong,Zhang, Chengbo,Liu, Xiaodong,Qiu, Song,Lu, Ping,Shen, Fangzhong,Zhang, Jingying,Ma, Yuguang
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