Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, Via Gobetti 101, 40129 Bologna (Italy); Present address: Photosciences and Photonics, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695 019, Kerala (India).
Chemistry. 2014 Jan 3;20(1):223-31. doi: 10.1002/chem.201303481. Epub 2013 Dec 6.
The photophysical properties of a supramolecular fullerene-porphyrin ensemble resulting from the self-assembly of a pyrrolidinofullerene-imidazole derivative (F1) with a multimetalloporphyrin array constructed around a hexasubstituted fullerene core (F(ZnP)12) have been investigated. The fullerene hexa-adduct core of the host system does not play any active role in the cascade of photoinduced events of the supramolecular ensemble, indeed no intercomponent photoinduced processes could be observed in host F(ZnP)12. In contrast, upon axial coordination with the monosubstituted fullerene guest F1, a quantitative quenching of the fluorescence signal of the metalloporphyrins was observed for the supramolecular complex [F(ZnP)12(F1)n] both in polar and nonpolar solvents. In toluene, the supramolecular ensemble exhibits a charge transfer emission centered around nm, suggesting the occurrence of intramolecular face-to-face interactions of F1 with neighboring metalloporphyrin moieties within the self-assembled photoactive array. This mechanism is supported by the fact that a one order of magnitude increase in the binding constant was observed for the supramolecular complex [F(ZnP)12(F1)n] when compared with a reference system lacking the pyrrolidinofullerene unit. In benzonitrile, a long-lived charge-separated state (τ=0.3 μs) has been detected for the supramolecular adduct.
超分子富勒烯-卟啉聚集体的光物理性质是通过吡咯烷富勒烯-咪唑衍生物（F1）与多金属卟啉阵列自组装得到的，该阵列构建在六取代富勒烯核心（F（ZnP）12）周围。主体系统的富勒烯六加合物核心在超分子聚集体的光诱导事件级联中没有发挥任何积极作用，实际上在主体 F（ZnP）12 中观察不到任何相间光诱导过程。相比之下，在轴向与单取代富勒烯客体 F1 配位后，在极性和非极性溶剂中，超分子配合物[F（ZnP）12（F1）n]的金属卟啉荧光信号都被定量猝灭。在甲苯中，超分子聚集体表现出以 nm 为中心的电荷转移发射，表明在自组装光活性阵列中 F1 与相邻金属卟啉部分之间发生了分子内面对面相互作用。这一机制得到了支持，即与缺乏吡咯烷富勒烯单元的参比体系相比，超分子配合物[F（ZnP）12（F1）n]的结合常数增加了一个数量级。在苯腈中，超分子加合物检测到长寿命的电荷分离态（τ=0.3 μs）。
