Department of Chemistry and Argonne-Northwestern Solar Energy Research (ANSER) Center, Northwestern University, Evanston, Illinois 60208-3113, USA.
J Am Chem Soc. 2010 Feb 3;132(4):1383-8. doi: 10.1021/ja908605s.
A series of zinc porphyrin arrays comprised of a meso-meso linked porphyrin dimer, a meta-phenylene linked dimer, gable-like tetramers consisting of the meso-meso linked dimers bridged via a meta-phenylene linker, and a dodecameric ring composed of this alternating dimeric pattern were singly oxidized, and intramolecular hole hopping between the porphyrin moieties was probed using electron paramagnetic resonance (EPR) spectroscopy. Electron nuclear double resonance (ENDOR) spectroscopy was also used to probe hole hopping within the dimers. Rapid hole hopping occurs between both porphyrins within both dimers and among three porphyrins of the tetramers with rates >10(7) s(-1) at 290 K. Additionally, the hole hops among 8-12 porphyrins in the dodecameric ring with a rate that is >10(7) s(-1) at 290 K, but hopping is slow at 180 K. These results show that hole hopping is rapid even though the meta-phenyl bridges and direct meso-meso linkages do not provide optimal electronic coupling between the porphyrins within these multiporphyrin arrays. This greatly expands the scope of possible structures that can be employed to tailor the design of long distance charge transport systems.
一系列由间位-间位连接的卟啉二聚体、亚苯基连接的二聚体、由间位-间位连接的二聚体通过亚苯基桥接而成的山字形四聚体以及由这种交替二聚体模式组成的十二聚体环组成的锌卟啉阵列被单独氧化，并使用电子顺磁共振（EPR）光谱探测卟啉部分之间的分子内空穴跳跃。电子-核双共振（ENDOR）光谱也用于探测二聚体中的空穴跳跃。在 290 K 下，两种二聚体中的两个卟啉之间以及四聚体中的三个卟啉之间的空穴跳跃速率>10(7) s(-1)。此外，十二聚体环中的 8-12 个卟啉之间的空穴跳跃速率>10(7) s(-1)，但在 180 K 时跳跃缓慢。这些结果表明，即使亚苯基桥和直接的间位-间位连接不能在这些多卟啉阵列中的卟啉之间提供最佳的电子耦合，空穴跳跃也很迅速。这大大扩展了可能的结构范围，可以用于设计长距离电荷传输系统。
