Derivatized Benzothiazoles as Two-Photon-Absorbing Organic Photosensitizers Active under Near Infrared Light Irradiation
Derivatized Benzothiazoles as Two-Photon-Absorbing Organic Photosensitizers Active under Near Infrared Light Irradiation
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DOI：
10.1021/jacs.2c12244
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发表时间：
2023-02-02
影响因子：
15
通讯作者：
Sun, Yujie
中科院分区：
文献类型：
--
作者：
Kundu, Bidyut Kumar;Han, Guanqun;Sun, Yujie
均相有机光催化通常需要分子光敏剂在紫外-可见光(UV/Vis)区域吸收，因为UV/Vis光子具有足够的能量来激发这些单光子吸收光敏剂到所需的激发态。然而，UV/Vis光照射有许多潜在的局限性，特别是在大规模应用中，如对反应介质的穿透率低，被底物和助催化剂竞争吸收，以及与具有光敏功能的底物不兼容。事实上，如果能够利用近红外(NIR)光子来驱动靶反应，这些缺点就可以有效地避免。在这里，我们报道了两种苯并噻唑类化合物作为新型的双光子吸收(TPA)有机光敏剂，它们可以在廉价的LED作为光源的近红外光照射下工作。我们证明，通过对含有联苯并噻唑核和亚胺桥的给体-pi-受体-pi-给体共轭结构进行司法调制，可以在近红外区获得优异的双光子吸收能力，在850 nm处接近2000GM。这些苯并噻唑衍生的TPA有机光敏剂具有高的量子产率(接近0.5)，在850 nm的辐射下表现出优异的性能，能够驱动各种含O2的有机反应，表现出较大的穿透深度，优于蓝光照射。进行了一系列光物理和计算研究，以阐明导致观察到的TPA能力的潜在电子态。总体而言，这项工作突出了利用双光子吸收机制开发在近红外区域工作的无Ru/Ir有机光敏剂的前景。
Homogeneous organic photocatalysis typically requires molecular photosensitizers absorbing in the ultraviolet-visible (UV/vis) region, because UV/ vis photons possess the sufficient energy to excite those one-photon-absorbing photosensitizers to the desired excited states. However, UV/vis light irradiation has many potential limitations, especially for large-scale applications, such as low penetration through reaction media, competing absorption by substrates and co catalysts, and incompatibility with substrates bearing light-sensitive functionalities. In fact, these drawbacks can be effectively avoided if near infrared (NIR) photons can be utilized to drive the target reactions. Herein, we report two benzothiazolederived compounds as novel two-photon-absorbing (TPA) organic photo sensitizers, which can function under NIR light irradiation using inexpensive LED as the light source. We demonstrate that by judicially modulating the donor-pi-acceptor-pi-donor-conjugated structure containing a bibenzothiazole core and imine bridges, excellent two-photon absorption capability in the NIR region can be achieved, approaching 2000 GM at 850 nm. Together with large quantum yields (similar to 0.5), these benzothiazole-derived TPA organic photosensitizers exhibit excellent performance in driving various O2-involved organic reactions upon irradiation at 850 nm, showing great penetration depth, superior to that upon blue light irradiation. A suite of photophysical and computational studies were performed to shed light on the underlying electronic states responsible for the observed TPA capability. Overall, this work highlights the promise of developing Ru/ Ir-free organic photosensitizers operative in the NIR region by taking advantage of the two-photon absorption mechanism.