Ansteatt Sara, Gelfand Rachel, Pelton Matthew, Ptaszek Marcin
Department of Chemistry and Biochemistry, University of Maryland, Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA.
Department of Physics, University of Maryland, Baltimore County (UMBC), 1000 Hilltop Circle, Baltimore, MD 21250, USA.
Chemistry. 2023 Oct 18;29(58):e202301571. doi: 10.1002/chem.202301571. Epub 2023 Sep 11.
In photosynthetic light-harvesting complexes, strong interaction between chromophores enables efficient absorption of solar radiation and has been suggested to enable ultrafast energy funneling to the reaction center. To examine whether similar effects can be realized in synthetic systems, and to determine the mechanisms of energy transfer, we synthesized and characterized a series of bioinspired arrays containing strongly-coupled BODIPY dimers as energy donors and chlorin derivatives as energy acceptors. The BODIPY dimers feature broad absorption in the range of 500-600 nm, complementing the chlorin absorption to provide absorption across the entire visible spectrum. Ultrafast (~10 ps) energy transfer was observed from photoexcited BODIPY dyads to chlorin subunits. Surprisingly, the energy-transfer rate is nearly independent of the position where the BODIPY dimer is attached to the chlorin and of the type of connecting linker. In addition, the energy-transfer rate from BODIPY dimers to chlorin is slower than the corresponding rate in arrays containing BODIPY monomers. The lower rate, corresponding to less efficient through-bond transfer, is most likely due to weaker electronic coupling between the ground state of the chlorin acceptor and the delocalized electronic state of the BODIPY dimer, compared to the localized state of a BODIPY monomer.
在光合捕光复合物中，发色团之间的强相互作用能够有效吸收太阳辐射，并且有人认为这能使能量超快地汇聚到反应中心。为了研究在合成体系中是否能实现类似的效果，并确定能量转移的机制，我们合成并表征了一系列受生物启发的阵列，其中包含强耦合的BODIPY二聚体作为能量供体和二氢卟吩衍生物作为能量受体。BODIPY二聚体在500 - 600 nm范围内具有宽吸收，与二氢卟吩的吸收互补，从而在整个可见光谱范围内提供吸收。观察到从光激发的BODIPY二元体到二氢卟吩亚基的超快（~10 ps）能量转移。令人惊讶的是，能量转移速率几乎与BODIPY二聚体连接到二氢卟吩的位置以及连接接头的类型无关。此外，从BODIPY二聚体到二氢卟吩的能量转移速率比含有BODIPY单体的阵列中的相应速率慢。较低的速率对应着效率较低的通过键转移，这很可能是由于与BODIPY单体的局域态相比，二氢卟吩受体的基态与BODIPY二聚体的离域电子态之间的电子耦合较弱。
