Ziessel Raymond, Stachelek Patrycja, Harriman Anthony, Hedley Gordon J, Roland Thomas, Ruseckas Arvydas, Samuel Ifor D W
Molecular Photonics Laboratory, School of Chemistry , Bedson Building, Newcastle University , Newcastle upon Tyne NE1 7RU , United Kingdom.
Organic Semiconductor Centre, SUPA, School of Physics & Astronomy , Physical Science Building, University of St. Andrews , North Haugh, St Andrews KY16 9SS , United Kingdom.
J Phys Chem A. 2018 May 10;122(18):4437-4447. doi: 10.1021/acs.jpca.8b02415. Epub 2018 Apr 25.
A pair of complementary molecular dyads have been synthesized around a 1,2-diaminocyclohexyl spacer that itself undergoes ring inversion. Despite these conformational exchange processes, the donor and acceptor occupy quite restricted spatial regions, and they are not interchangeable. The donor and acceptor pair comprise disparate boron dipyrromethene dyes selected to display favorable electronic energy transfer (EET). Steady-state emission spectroscopy confirms that through-space EET from donor to acceptor is almost quantitative, aided by the relatively short separations. Ultrafast time-resolved fluorescence spectroscopy has allowed determination of the rates of EET for both dyads. Surprisingly, in view of the close proximity of donor and acceptor (center-to-center separations less than 20 Å), the EET dynamics are well-accounted for in terms of the computed molecular conformations and conventional Förster theory. One dyad appears as a single family of conformations, but EET for the second dyad corresponds to dual-exponential kinetics. In this latter case, an intramolecular hydrogen bond helps stabilize an open geometry, wherein EET is relatively slow.
围绕一个本身会发生环反转的1,2 - 二氨基环己基间隔基合成了一对互补的分子二元体。尽管存在这些构象交换过程，但供体和受体占据相当受限的空间区域，且它们不可互换。供体和受体对由不同的硼二吡咯亚甲基染料组成，这些染料被选择用于展示有利的电子能量转移（EET）。稳态发射光谱证实，由于间隔相对较短，从供体到受体的空间EET几乎是定量的。超快时间分辨荧光光谱已能够测定两个二元体的EET速率。令人惊讶的是，鉴于供体和受体的紧密接近（中心到中心间距小于20 Å），根据计算出的分子构象和传统的福斯特理论，EET动力学得到了很好的解释。一个二元体呈现为单一的构象家族，但第二个二元体的EET对应于双指数动力学。在后一种情况下，分子内氢键有助于稳定一种开放几何结构，其中EET相对较慢。
