Garain Swadhin, Würthner Frank
Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
Center for Nanosystems Chemistry (CNC), Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany.
Chem Commun (Camb). 2025 Feb 13;61(15):3081-3092. doi: 10.1039/d4cc06070a.
Modulation of optical properties through smart protein matrices is exemplified by a few examples in nature such as rhodopsin (absorption wavelength tuning) and the green fluorescence protein (emission), but in general, the scope found in nature for the matrix-controlled photofunctions remains rather limited. In this review, we present cyclophane-based supramolecular host-guest complexes for which electronic interactions between the cyclophane host and mostly planar aromatic guest molecules can actively modulate excited-state properties in a more advanced way involving both singlet and triplet excited states. We begin by highlighting photofunctional host-guest systems for on-off fluorescence switching and chiroptical functions using bay-functionalized perylene bisimide cyclophanes. Next, we examine the impact of π-extension in perylene bisimide cyclophanes for multiple guest binding, showcasing photofunctional properties including circularly polarized luminescence (CPL). We then focus on triplet-generating cyclophanes, coronene bisimide cyclophane, with high intersystem crossing (ISC) rates, where we demonstrate modulation of excited state pathways upon guest encapsulation and triplet sensitization through phosphorescence and thermally activated delayed fluorescence (TADF). Furthermore, using supramolecular strategies, we advance non-covalent designs, involving either heavy-atom-based Pt(acac) guests or heavy-atom free charge transfer complexes, for triplet harvesting under ambient conditions and demonstrate the role of supramolecular nanoenvironments in stabilizing triplet excitons in aerated solutions. Additionally, we showcase examples for triplet-triplet annihilation (TTA) upconversion in defined cyclophane complexes in aqueous solutions and the application of host-guest chemistry in organic light-emitting diodes (OLEDs).
通过智能蛋白质基质调节光学性质的例子在自然界中有一些，如视紫红质（吸收波长调谐）和绿色荧光蛋白（发射），但总体而言，自然界中基质控制的光功能范围仍然相当有限。在本综述中，我们展示了基于环番的超分子主客体复合物，其中环番主体与大多为平面芳香族客体分子之间的电子相互作用可以以更先进的方式积极调节激发态性质，涉及单重态和三重态激发态。我们首先强调使用海湾功能化苝二酰亚胺环番实现开关荧光切换和手性光学功能的光功能主客体系统。接下来，我们研究苝二酰亚胺环番中π-扩展对多个客体结合的影响，展示包括圆偏振发光（CPL）在内的光功能性质。然后我们关注具有高系间窜越（ISC）速率的三重态生成环番——蒄二酰亚胺环番，在其中我们展示了客体包封时激发态途径的调节以及通过磷光和热激活延迟荧光（TADF）实现的三重态敏化。此外，我们使用超分子策略推进非共价设计，涉及基于重原子的Pt(acac)客体或无重原子的电荷转移复合物，用于在环境条件下进行三重态捕获，并展示超分子纳米环境在稳定充气溶液中三重态激子方面的作用。此外，我们展示了在水溶液中特定环番复合物中三重态-三重态湮灭（TTA）上转换的例子以及主客体化学在有机发光二极管（OLED）中的应用。
