| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
We synthesized a new chiral 2,2'-bipyridine ligand possessing R (+) -alpha-methylbenzyeamine, 5,5'-di (-) -methylbenzylamido-4,4'-6,6'-tetramethyl-2,2'-bipyridine (-) -tmdcbpy, and its Cu (I) complexes, [Cu ( (-) -tmdcbpy) (PPh_3) _2] 1, [Cu ( (-) -tmdcbpy) (P (C_6H_4-SO_3-m) Ph_2) _2] ^-2, [Cu ( (-) -tmdcbpy) ( (+) -diop) ] ^+3, and [Cu ( (-) -tmdcbpy) ( (-) -diop) ] ^+ 4. Using these Cu (I) complexes, stereoselective photoreduction of [Cu (edta) ] ^-was successfully carried out upon irradiation of near UV light corresponding to the MLCT absorption band of these Cu (I) complexes. The best stereoselectivity was 44%e.e. when 1 was used in ethanol-water (75 : 25 v/v). On the other hand, the stereoselectivity decreases to about 17%e.e. when 2 was used. The quenching experiments with [Co (edta) ] ^-indicated clearly that the reaction of 1 proceeds through dynamic and static quenching mechanism but the reaction of 2 takes place only through static quenching mechanism. These interesting diff
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erences between 1 and 2 are interpreted in terms of the electrostatic interaction : because 1 is positively charged, 1 can easily form an adduct with negatively charged [Co (edta) ] ^-and the interaction of [Cu^<11> ( (-) -tmdcbpy) (PPh_3) _2] ^<2+> with [Co^<11> (edta) ] ^<2->is strong due to the electrostatic attraction. On the other hand, the negatively charge 2 can not form a stable adduct in the ground state, and also the interaction of [Cu^<11> ( (-) -tmdcbpy) (P (C_6H_4SO_3-m) Ph) _2] ^0with [Co (edta) ] ^<2->is weak because of the lack of electrostatic attraction.
Then, photo-asymmetric synthesis of [Co (edta) ] ^-was successfully carried out from Co (OAc) _2and H_4edta or Na_4edta, using these Cu (I) complexes with oxygen gas under upon irradiation of near UV light., In this photosynthetic reaction, DELTA- [Co (edta) ] ^-was produced in the excess when H_4edta was used. This reaction was possible only in DMSO,and the selectivity significantly depends on the kind of edta source, counter anion of Co salt. Less
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