Assemblies of Boron Dipyrromethene/Porphyrin, Phthalocyanine, and C60 Moieties as Artificial Models of Photosynthesis: Synthesis, Supramolecular Interactions, and Photophysical Studies

다국어 초록 (Multilingual Abstract)

A series of light‐harvesting conjugates based on a zinc(II) phthalocyanine core with either two or four boron dipyrromethene (BODIPY) or porphyrin units have been synthesized and characterized. The conjugation of BODIPY/porphyrin units can extend the absorptions of the phthalocyanine core to cover most of the visible region. Upon addition of an imidazole‐substituted C60 (C60Im), it can axially bind to the zinc(II) center of the phthalocyanine core through metal–ligand interactions. The resulting complexes form photosynthetic antenna‐reaction center mimics in which the BODIPY/porphyrin units serve as the antennas to capture the light and transfer the energy to the phthalocyanine core by efficient excitation energy transfer. The excited phthalocyanine is then quenched by the axially bound C60Im moiety by electron transfer, which has been supported by computational studies. The photoinduced processes of the assemblies have been studied in detail by various steady‐state and time‐resolved spectroscopic methods. By femtosecond transient absorption spectroscopic studies, the lifetimes of the charge‐separated state of the bis(BODIPY) and bis(porphyrin) systems have been determined to be 3.2 and 4.0 ns, respectively.
See the light! By careful selection of chromophores and redox‐active units, a series of supramolecular photosynthetic antenna‐reaction center mimics have been constructed (see scheme), of which the lifetime of the charge‐separated state is as long as 4 ns.