Catalysis on Photoinduced Electron Transfer

光诱导电子转移的催化

基本信息

批准号：
07454195
负责人：
FUKUZUMI Shunichi
金额：
$ 4.67万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

We have found that Sc^<3+> ion is highly effective for the reduction of benzaldehyde and its derivatives by an NADH analogue at room temperature. The apparent reactivity is shown to be comparable with the enzyme. The catalytic mechanism is discussed based on the comparison of the catalysis of Sc^<3+> on the electron transfer reactions of carbonyl compounds. The hydride transfer reaction from 10-methyl-9,10-dihydroacridine (AcrH_2) to p-benzoquinone (Q) is catalyzed by various metal ions such as Mg^<2+> and rare-earth metal ions in acetonitrile (MeCN). Among triflate salts of metal ions examined, Sc (OTf) _3 was the most effective. The observed second-order rate constant increases with an increase in [Sc^<3+>] at low concentrations, changing to second order dependence at high concentrations. Essentially the same catalytic behavior of Sc^<3+> was observed in the electron transfer reduction of Q by CoTPP (TPP=tetraphenylporphyrin dianion) in MeCN.The second-order dependence of the rate constant with respect to [Sc^<3+>] is ascribed to formation of a 1 : 2 complex between Q^<・-> and Sc^<3+>. The formation of Q^<・->-2Sc^<3+> is confirmed by the ESR spectrum which exhibits the super hyperfine interaction with two equivalent Sc nuclei. Thus, the hydride transfer from AcrH_2 to Q may proceed via Sc^<3+>-catalyzed electron transfer from AcrH_2 to Q.When AcrH_2 is replaced by 1-benzyl-1,4-dihydronicotinamide (BNAH) which is a stronger electron donor than AcrH_2, benzaldehyde and its derivatives are reduced by BNAH efficiently in the presence of Sc^<3+> in MeCN at room temperature to yield the corresponding alcohols. The Sc^<3+> also catalyzes photoinduced electron transfer from the excited state of Ru (bpy) _3^<2+> to benzaldehydes in MeCN.Catalysis of metal ions on various thermal and photoinduced electron transfer reactions has been examined in detail.

我们发现Sc^<3+>离子在室温下通过NADH类似物的苯甲醛及其衍生物的衍生物非常有效。表观反应性与酶相媲美。基于SC^<3+>的催化剂对羰基化合物的电子转移反应的催化剂的比较，讨论了催化机制。氢化物转移反应从10-甲基-9,10-二氢丙氨酸（ACRH_2）到p-苯醌（Q）的氢化物转移反应是由乙腈（MECN）中的各种金属离子（例如Mg^<2+>）和稀土金属离子催化的。在检查的金属离子的三叶盐中，SC（OTF）_3是最有效的。观察到的二阶速率常数随着低浓度的[SC^<3+>]的增加而增加，在高浓度下变为二阶依赖性。基本上，在MECN中，COTPP（Tpp = Tpp = Tetraphenylporphyrin dianion）的电子传输还原时观察到SC^<3+>的催化行为。 Q^<・-> -2SC^<3+>的形成是通过ESR谱证实的，ESR光谱表现出与两个等效SC核的超精细相互作用。这是，从ACRH_2到Q的水力转移可以通过Sc^<3+> - 催化电子从ACRH_2到Q。当Acrh_2被1-苯甲酰-1,4-二羟氨酮胺（BNAH）取代时，这是比Acrh_2，<benzaldehyde anh sc的效率^y+sc^y+sc^scy的供体，这是一个更强的电子供体。 MECN在室温下产生相应的醇。 SC^<3+>还详细研究了金属离子在MECN中的ru（bpy）_3^<2+>催化电子诱导的电子转移到MECN的苯甲醛。金属离子在各种热和光诱导的电子转移反应上的催化。