Flamigni Lucia, Ventura Barbara, Oliva Ana I, Ballester Pablo
Istituto ISOF-CNR, Via P. Gobetti 101, 40129 Bologna, Italy.
Chemistry. 2008;14(14):4214-24. doi: 10.1002/chem.200800026.
We describe the construction of self-assembled double-decker porphyrin arrays built up from two covalently connected trimeric Zn-porphyrin units that are joined together by metal-coordination bonds with diamine ligands. We used three different types of diamine ligands: 1,4-diaza[2.2.2]bicyclooctane (DABCO), 4,4'-bipyridine (BIPY), and 5,15-bis(4-pyridyl)-10,20-diphenylporphyrin (DPYP). The ligands act as pillars, through two axial coordination bonds with the porphyrinic Zn(II) ions, to block the planes of the porphyrin units in an almost cofacial orientation and inducing the formation of a trigonal prismatic structure. The spectroscopic and photophysical properties of the Zn-trisporphyrin component were determined as well as those of the resulting multimolecular cagelike assemblies. The double-decker assembly with DPYP as the pillars constitutes a nonameric porphyrin aggregate. Although this assembly is thermodynamically less stable than those containing DABCO or BIPY, efficient photoinduced energy transfer occurs (96% yield) from the trisporphyrin base units to the DPYP side walls. The rate of the energy-transfer process is in good agreement with that calculated for a dipole-dipole (Förster) mechanism corrected for the unfavorable orientation geometry of the donor and the axially bound acceptor.
我们描述了由两个通过金属配位键与二胺配体连接在一起的共价连接的三聚体锌卟啉单元构建的自组装双层卟啉阵列的构建。我们使用了三种不同类型的二胺配体:1,4-二氮杂[2.2.2]双环辛烷(DABCO)、4,4'-联吡啶(BIPY)和5,15-双(4-吡啶基)-10,20-二苯基卟啉(DPYP)。这些配体通过与卟啉锌(II)离子的两个轴向配位键充当支柱,以几乎共面的取向阻挡卟啉单元的平面,并诱导形成三角棱柱结构。测定了锌三卟啉组分以及所得多分子笼状组装体的光谱和光物理性质。以DPYP为支柱的双层组装体构成了九聚体卟啉聚集体。尽管这种组装体在热力学上比含有DABCO或BIPY的组装体更不稳定,但从三卟啉基本单元到DPYP侧壁发生了有效的光诱导能量转移(产率96%)。能量转移过程的速率与针对供体和轴向结合受体的不利取向几何形状校正的偶极-偶极(福斯特)机制计算的速率非常一致。