State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China.
Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.
Phys Chem Chem Phys. 2021 Nov 24;23(45):25455-25466. doi: 10.1039/d1cp02912f.
When organic electron donor (D) and acceptor (A) chromophores are linked together, an electron transfer (ET) state can take place. When a short bridge such as one Sigma bond is used to link the donor and the acceptor, complete charge separation is difficult to access and one usually observes an intramolecular charge transfer (CT) state instead. Due to the inevitable coupling between the donor and the acceptor in compact organic chromophores, the most common decay pathway for the CT state is charge recombination, which may lead to a distinct longer wavelength fluorescence emission or non-radiative dissipation of the excited state energy. However, recent studies have shown that unique excited state dynamics can be observed when the CT state is involved during both forward and backward intersystem crossing (ISC) from singlet excited states to triplet excited states in organic chromophores. Analysis of the mechanism for ISC involving the CT state has received much attention over the last decade. In this perspective, we present a collection of molecular design rationales, spectroscopy and theoretical investigations that provide insights into the mechanism of the ISC involving the CT state in compact organic chromophores. We hope that this perspective will prove beneficial for researchers to design novel compact organic chromophores with a predictable ISC property for future biochemical and optoelectronic applications.
当有机电子给体 (D) 和受体 (A) 发色团连接在一起时，就可以发生电子转移 (ET) 态。当使用短桥（如单键）将供体和受体连接时，很难实现完全的电荷分离，通常会观察到分子内电荷转移 (CT) 态。由于紧密的有机发色团中供体和受体之间不可避免的耦合，CT 态最常见的衰减途径是电荷复合，这可能导致荧光发射波长明显更长或激发态能量的非辐射耗散。然而，最近的研究表明，当 CT 态参与有机发色团中从单重激发态到三重激发态的正向和反向系间窜越 (ISC) 时，可以观察到独特的激发态动力学。过去十年中，对涉及 CT 态的 ISC 机制的分析引起了广泛关注。在这篇观点文章中，我们介绍了一系列分子设计原理、光谱和理论研究，这些研究为理解紧凑有机发色团中涉及 CT 态的 ISC 机制提供了深入的见解。我们希望这篇观点文章有助于研究人员设计具有可预测 ISC 性质的新型紧凑有机发色团，以用于未来的生物化学和光电应用。
