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Relations between molecular structures of europium complexes and their luminescent properties were investigated. Europium complex with β-diketones and two different phosphine oxides 8 was highly soluble in fluorinated medium, and realized largest fluorescence intensities. The luminous intensity of ultraviolet light emitting diodes devices (LEDs) whose fluorescence layer consists of fluorinated polymer and 8 was over 200 mcd (20 mA). Fluorescence compounds of this type are promising for application in next-generation white LEDs. Moreover, we proposed a novel molecular design of europium complex with asymmetric diphosphine dioxide.

The lithium storage mechanism of perylene-based disordered carbon (PBDC) heat-treated at 550 °C, which is a promising material for use as the anode in lithium-ion cells, was studied by solid-state 7 Li NMR and ESR analysis. PBDC is one of carbonaceous materials containing condensed aromatic rings, and showed a high reversible specific capacity of about 800 mAh/g with large hysteresis in the charge/discharge profile. 7 Li NMR spectra for the lithiated PBDCs exhibited two bands at the insertion of above 900 mAh/g. Band A at 7 ppm and band B at 0.3 ppm versus LiCl were assigned to lithium in reversible and irreversible storage sites, respectively. The results of 7 Li NMR analysis supported the presence of ionic lithium located on aromatic rings. ESR spectra for PBDC lithiated by over 300 mAh/g showed sharp and broad signals. The intensity of the broad signal varied significantly with lithium insertion. The variations of 7 Li NMR and ESR spectra with lithium insertion were interpreted by the presence of two kinds of insertion sites: the layer structure site (L-site) and the unorganized carbon site (U-site) located between the L-sites.