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

本研究的目的是阐明受激态羰基化合物与阳离子、刘易斯酸和质子酸形成络合物的特点，并评价通过络合物的形成控制光反应的可能性。在荧光光谱中观察到各种羰基化合物与阳离子、刘易斯酸和质子酸的单重激发态相互作用。与阳离子形成1：1和1：2络合物，与刘易斯酸和质子酸仅形成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，相互作用按阳离子、刘易斯酸和质子酸的顺序较强。羰基化合物的基态没有相互作用.从溶剂效应和阳离子影响的结果来看，羰基化合物的单重激发态与阳离子的配位作用是形成配合物的主要原因。类似的配位可以用刘易斯酸和普罗蒂酸进行。与阳离子形成的络合物降低了从羰基化合物的单重激发态进行的芳香族羰基化合物的二聚的量子产率，并且抑制了从酰亚胺的单重激发态进行的烯烃插入到芳香族酰亚胺的C-N键中的反应。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效应，其中与阳离子形成络合物延长了羰基化合物激发单重态的寿命.从以上结果可以推断出与阳离子形成络合物的规律，为控制光反应提供了一种有效的方法。刘易斯酸和质子酸的络合物形成也被发现是有效的控制光反应。

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.