Photochemical Reaction of Charge-transfer Complexes

点击翻译按钮获取中文摘要

We have investigated dependence of the net energy deference, -ΔGィイD2BET'ィエD2, between the ground state and radical ion pairs on reactivity of the excited state of the charge-transfer (CT) complexes between acenaphthylene (CAN) and a series of electron acceptors such as nitriles, acid anhydrides and 1,4-benzoquinones. The CT complexes were selectively excited in dichloroethane with 546.1 nm light to determine quantum yield of reaction, ΦィイD2R,ィエD2, or >500 nm light to investigate the reaction products. Plots of ΦィイD2RィエD2 against -ΔGィイD2BETィエD2 shows that CT complexes with large -ΔGィイD2BETィエD2 values give net reaction products; however, with lowering of -ΔGィイD2BETィエD2, ΦィイD2RィエD2 tends to decrease and finally reaches zero when -ΔGィイD2BETィエD2 is lower than 1.7 Ev. When -ΔGィイD2BETィエD2 is lower than the threshold, excitation of the CT complexes of CAN with acceptors did not result in any reaction products. It was concluded that -ΔGィイD2BETィエD2 clearly controls the reactivity of excited CT complexes by affecting the backward electron transfer rate from the resulting radical ions.