Department of Material and Life Science, Graduate School of Engineering, Osaka University, Suita, Japan.
Chemistry. 2012 Oct 22;18(43):13844-53. doi: 10.1002/chem.201202265. Epub 2012 Sep 20.
New multi-modular donor-acceptor conjugates featuring zinc porphyrin (ZnP), catechol-chelated boron dipyrrin (BDP), triphenylamine (TPA) and fullerene (C(60)), or naphthalenediimide (NDI) have been newly designed and synthesized as photosynthetic antenna and reaction-center mimics. The X-ray structure of triphenylamine-BDP is also reported. The wide-band capturing polyad revealed ultrafast energy-transfer (k(ENT) =1.0 × 10(12) s(-1)) from the singlet excited BDP to the covalently linked ZnP owing to close proximity and favorable orientation of the entities. Introducing either fullerene or naphthalenediimide electron acceptors to the TPA-BDP-ZnP triad through metal-ligand axial coordination resulted in electron donor-acceptor polyads whose structures were revealed by spectroscopic, electrochemical and computational studies. Excitation of the electron donor, zinc porphyrin resulted in rapid electron-transfer to coordinated fullerene or naphthalenediimide yielding charge separated ion-pair species. The measured electron transfer rate constants from femtosecond transient spectral technique in non-polar toluene were in the range of 5.0 × 10(9)-3.5 × 10(10) s(-1). Stabilization of the charge-separated state in these multi-modular donor-acceptor polyads is also observed to certain level.
新型多模块给体-受体化合物的特点是锌卟啉（ZnP）、邻苯二酚螯合二吡咯硼（BDP）、三苯胺（TPA）和富勒烯（C（60））或萘二酰亚胺（NDI），它们被新设计并合成作为光合作用天线和反应中心模拟物。还报道了三苯胺-BDP 的 X 射线结构。由于实体的近距离和有利取向，从单重激发的 BDP 到共价连接的 ZnP 的宽能带捕获聚集体显示出超快能量转移（k（ENT）=1.0×10（12）s（-1））。通过金属-配体轴向配位将富勒烯或萘二酰亚胺电子受体引入 TPA-BDP-ZnP 三联体中，导致电子给体-受体聚集体的结构通过光谱、电化学和计算研究揭示。锌卟啉作为电子给体的激发导致快速电子转移到配位的富勒烯或萘二酰亚胺上，生成电荷分离离子对物种。从飞秒瞬态光谱技术在非极性甲苯中的测量电子转移速率常数在 5.0×10（9）-3.5×10（10）s（-1）范围内。这些多模块给体-受体聚集体中电荷分离态的稳定也被观察到一定程度。
