conformations. A partially closed form permits reasonably close approach of the two porphyrin rings so that Förster energy transfer is efficient. In a fully extended form the two porphyrins are held too far apart for energy transfer to compete effectively with non-radiative decay of the ZnP excited singlet state. Triplet energy transfer is not observed, owing to unfavourable orientations for exchange coupling
已经合成了一系列共价连接的Zn–H 2
卟啉二聚体。所述连接由可变长度的柔性烷氧基链组成。吸收光谱表明,两个
卟啉环之间存在一些激子耦合,而荧光光谱表明,ZnP单元将单重态激发能转移到H 2上P.从时间分辨荧光研究得出结论,二聚体以不同的非平衡构象存在于溶液中。部分闭合的形式可以使两个
卟啉环合理地接近,从而使Förster能量传递高效。两种
卟啉以完全伸展的形式相隔太远,无法进行能量转移,无法有效地与ZnP激发单线态的非辐射衰变竞争。由于交换偶合的取向不利,未观察到三重态能量转移,而即使在极性溶剂中也未观察到氧化还原离子中间体。