The synthesis of the novel bidentate ligands 4,4'-bis(trifluoromethyl)-2,2'-bipyridine (4,4'-BTFMB), 5,5'-bis-(trifluoromethyl)-2,2'-bipyridine (5,5'-BTFMB), and 4,4',5,5'-tetrakis(trifluoromethyl)-2,2'-bipyridine (4,4',5,5'-TTFMB) is reported. The photophysical and photochemical properties of a series of tris-chelate complexes [Ru(bpy)"(BTFMB)3-n]2+ ( = 0-2; bpy = 2,2'-bipyridine) are described. From spectroscopic and electrochemical measurements, it has been shown that the BTFMB ligand has lower lying ir* levels which not only lead to significant changes in ground-and excited-state redox potentials but also exert relatively large effects on absorption and emission spectral properties. From measurements of emission lifetime and quantum yield at room temperature, the radiative (kr) and nonradiative (knr) decay rate constants were obtained. Trends in k", properties are understandable on the basis of the energy gap law. Possible applications in excited-state redox chemistry are also discussed.

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Competitive Energy and Electron-Transfer Quenching Across the Peptide-Bridge in Polypyridine Ruthenium(II)/Osmium(II) Binuclear Systems -[17 refs.]. -(FURUE, M.; ISHIBASHI, M.; SATOH, A.; OGUNI, T.; MARUYAMA, K.; SUMI, K.; KAMACHI, M.; Coord. Chem. Rev. 208 (2000) 103-113; Dep. Environ. Syst. Eng., Kochi Univ. Technol., Kochi 782, Japan; EN)

Recently, domestic paper demand has declined due to global economic recession. So, Japanese paper producers made scrap-and-build plans to concentrate production on larger and more efficient machines, thus reducing costs and have proceeded with these plans to improve revenue and enhance their competitiveness. Under these difficult circumstances, polyacrylamide(PAM)based dry strength resins(DSRs)is one of the best solutions for maintaining productivity and quality of paper.In order to overcome these problems, we have conducted the study based on the results for several model experiments that fixations of DSRs are different for pulps and PCC, and flocculation of PCC is also different, depending on ionicity(density)and molecular weight of DSR. As a result, we have developed novel PAM based DSRs for papers filled highly with PCC, which show excellent dry paper strength and high retention without excess flocculation of PCC fillers.