Control of Photochemical Reactions by Use of Complex Formation of Carbonyl Compounds with Cations

本研究的目的是阐明激发态羰基化合物与阳离子、Lewis酸和质酸形成络合物的特征，并评价利用该络合物形成的络合物控制光反应的可能性。获得的结果如下：1.在荧光光谱中观察到了各种羰基化合物的单重态激发态与阳离子、Lewis酸和质酸的相互作用。当与阳离子形成1：1和1：2络合物时，仅与Lewis酸和质酸形成1：1络合物。从荧光光谱变化得到的络合物形成的缔合常数来看，相互作用似乎按阳离子、Lewis酸和质酸的顺序较强。在所有情况下都没有观察到羰基化合物的基态相互作用。从溶剂效应和阳离子的影响来看，阳离子与羰基化合物单重态的配位似乎是形成络合物的原因。类似的配位作用也可以与Lewis酸和Proti cacid进行。与阳离子形成的络合物降低了从羰基化合物的单重态开始的芳香族羰基化合物二聚反应的量子产率，也抑制了从芳香族酰亚胺的单重态开始的烯烃插入芳香族酰亚胺的C-N键反应。此外，在光化学电子转移反应中观察到与阳离子形成络合物的显著加速作用，其中与阳离子形成的络合物延长了羰基化合物的激发单重态的寿命。从以上结果可以得出结论，阳离子络合物的形成为光反应的控制提供了一种有用的方法。与Lewis酸和质酸形成的络合物也被发现是控制光反应的有效方法。

The purposes of this investigation are clarification of the feature of the complex formation of excited carbonyl compounds with cation, Lewis acid, and protic acid, and evaluation of the possibility for controlling photoreactions by the complex formation.The results obtained are as follows :1. Interaction of the singlet excited states of various carbonyl compounds with cation, Lewis acid, and protic acid was observed in the fluorescence spectra. While 1:1 and 1:2 complex formation with cation was observed, only 1:1 complex formation with Lewis acid and protic acid was found. From the association constants for the complex formation obtained from the changes of the fluorescence spectra, the interaction seems to be stronger in order of cation, Lewis acid, and protic acid. No interaction of the ground state of the carbonyl compounds was observed in all cases.2. From the results of solvent effect and influence of cation, coordination of the cation to the singlet excited state of the carbonyl compounds seem to be responsible for the complex formation. Similar coordination may proceed with Lewis acid and proti cacid.3. The complex formation with cation decreased the quantum yield of the dimerization of an aromatic carbonyl compound which proceeded from the singlet excited state of the carbonyl compound, and suppressed also insertion reaction of alkenes into C-N bond of an aromatic imide which proceeded from the singlet excited state of the imide. Furthermore, remarkable acceleration effect of the complex formation with cation was observed in a photochemical electron-transfer reaction, in which the complex formation with cation prolonged the lifetime of the excited singlet state of the carbonyl compound. From the above results the complex formation with cation can be concluded to offer a useful method for controlling photoreactions. The complex formation with Lewis acid and protic acid was also found to be effective for controlling photoreactions.