Fukunaga Issei, Kobashi Shunsuke, Nagai Yuki, Horita Hiroki, Maeda Hiromitsu, Kobayashi Yoichi
Department of Applied Chemistry, College of Life Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, Japan.
Beilstein J Org Chem. 2025 Aug 5;21:1577-1586. doi: 10.3762/bjoc.21.121. eCollection 2025.
We report the excited-state dynamics of π-orthogonal donor-acceptor dyads based on perylene (Pe) and phenothiazine (PTZ), in which triphenylamine (TPA) units and a phenyl spacer were introduced to modulate donor strength and spatial separation. Among the series, Pe-PTZ(TPA) exhibits a distinct thermal equilibrium between the locally excited (LE) state of the PTZ moiety and the photoinduced charge-transfer (CT) state. Femtosecond to microsecond transient absorption spectroscopy reveals that this equilibrium is facilitated not simply by enhanced donor ability, but presumably by excited-state planarization of the PTZ moiety, which lowers the energy of the LE state of the PTZ moiety. In contrast, Pe-Ph-PTZ(TPA), in which the donor-acceptor distance is increased by a phenyl spacer, does not show clear equilibrium behavior. These results underscore the crucial role of excited-state structural relaxation in tuning photoinduced charge separation, and demonstrate that precise electronic and geometric design can enable controllable excited-state behavior in orthogonal molecular systems.
我们报道了基于苝（Pe）和吩噻嗪（PTZ）的π-正交供体-受体二元体系的激发态动力学，其中引入了三苯胺（TPA）单元和苯基间隔基来调节供体强度和空间距离。在该系列中，Pe-PTZ(TPA)在PTZ部分的局域激发（LE）态和光诱导电荷转移（CT）态之间表现出独特的热平衡。飞秒到微秒瞬态吸收光谱表明，这种平衡不仅通过增强供体能力来促进，还可能通过PTZ部分的激发态平面化来促进，这降低了PTZ部分LE态的能量。相比之下，供体-受体距离通过苯基间隔基增加的Pe-Ph-PTZ(TPA)没有表现出明显的平衡行为。这些结果强调了激发态结构弛豫在调节光诱导电荷分离中的关键作用，并表明精确的电子和几何设计能够在正交分子体系中实现可控的激发态行为。
