C-O-bond cleavage of esters with a naphthyl group in the higher triplet excited state during two-color two-laser flash photolysis
C-O-bond cleavage of esters with a naphthyl group in the higher triplet excited state during two-color two-laser flash photolysis
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DOI：
10.1002/chem.200600822
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发表时间：
2007-01-01
影响因子：
4.3
通讯作者：
Majima, Tetsuro
中科院分区：
文献类型：
--
作者：
Cai, Xichen;Sakamoto, Masanori;Majima, Tetsuro
在乙腈中进行双色双激光闪光光解过程中，发现了具有萘基的酯类 NpCOOR 和 RCO-ONp（Np=α 和 P-萘基（分别为 Np-α 和 Np-β，R= Ph 和 Me）的 C-O-键断裂。当 NpCO-OR 和 RCOONp 被激发到单重激发态 (S-1) 时，C-O 键断裂发生。另一方面，最低三重激发态（T-1）没有发生反应。在双色双激光闪光光解过程中，当使用第二激光将NpCOOR(T-1)和RCO-ONp(T-1)激发到更高的三重激发态(T-n)时，发生C-O键断裂。 C-O-键裂解量子产率（Phi）是根据在激光闪光内消失的Tjstate酯与第二激光强度的关系图来估计的。 (NpCO)-Np-beta-OPh(T-n) 中的 C-O 键裂解比 (NpCO)-Np-α-OPh(T-n) 中发生的效率更高，而 PhCO-(ONp)-Np-beta(T-n) 中的 C-O 键裂解比 PhCO-O Phi Np(T-n) 中的发生效率更高。具有Ph和β-Np基团的酯的Phi值大于具有Ph和α-Np基团的酯的Phi值。 MeCO-(ONp)-Np-alpha(T-n)的Phi值与PhCO-ONp(T-n)相似，而MeCO-(ONp)-Np-beta(T-n)的Phi值远小于PhCO-ONp(T-n)和MeCO-(ONp)-Np-alpha(T-n)的Phi值。另一方面，在NpCO-OMe(T-n)中没有观察到C-O键断裂。 Phi 值取决于酯上基团（Np、Ph 和 Me）的特征。 R 是否分别为具有或不具有 pi 电子的 Ph 或 Me，对于 C-O 键断裂很重要。换句话说，包括Np和酯基的T i 态的电子离域对于NpCO-OR(T-n)和RCO-ONp(T-n)中C-O-键断裂的发生是必要的。
A C-O-bond cleavage of esters having a naphthyl group, NpCOOR and RCO-ONp (Np=alpha and P-naphthyl (Np-alpha and Np-beta, respectively), R= Ph and Me), was found during the two-color two-laser flash photolysis in acetonitrile. The C-O-bond cleavage occurred when NpCO-OR and RCOONp were excited to the singlet excited states (S-1). On the other hand, no reaction occurred from the lowest triplet excited states (T-1). When NpCOOR(T-1) and RCO-ONp(T-1) were excited to the higher triplet excited states (T-n) using the second laser during the two-color two-laser flash photolysis, the C-O-bond cleavage occurred. The C-O-bond cleavage quantum yield (Phi) was estimated from the plots of the Tjstate esters disappeared within a laser flash versus the second laser intensities. The C-O-bond cleavage in (NpCO)-Np-beta-OPh(T-n) occurred more efficiently than in (NpCO)-Np-alpha-OPh(T-n) and that in PhCO-(ONp)-Np-beta(T-n) occurred more efficiently than in PhCO-O Phi Np(T-n). The Phi value for ester with Ph and beta-Np groups was larger than that for ester with Ph and alpha-Np groups. The Phi value for MeCO-(ONp)-Np-alpha(T-n) was similar to those for PhCO-ONp(T-n), while that for MeCO-(ONp)-Np-beta(T-n) was much smaller than those for PhCO-ONp(T-n) and MeCO-(ONp)-Np-alpha(T-n). On the other hand, no C-O-bond cleavage was observed in NpCO-OMe(T-n). The Phi value depended on the characters of the groups (Np, Ph, and Me) on the ester. Whether R is Ph or Me with or without pi electron, respectively, is important for the C-O-bond cleavage. In other words, electronic delocalization of the T, state including Np and ester groups is necessary for the occurrence of the C-O-bond cleavage in NpCO-OR(T-n) and RCO-ONp(T-n).