具有强可见光吸收的富勒烯-Bodipy衍生物作为光催化剂在硫醚光催化氧化中的应用

以氟硼吡咯染料（Bodipy）做为光吸收天线，富勒烯作为分子内自旋转换单元，分别利用前者的强吸光以及后者的高效系间窜越的优点，制备了吸收波长灵活可调、无重原子、具有强可见光吸收能力、长寿命三重激发态（92.1 μs）的二元（Dyad）、三元化合物（Triad）做为有机三重态光敏剂；其中Triad具有宽谱带可见光吸收能力，提高了光敏剂参与的分子间能量转移或电子转移过程的效率。与传统的Ru（Ⅱ）配合物等三重态光敏剂相比，光催化硫醚氧化的反应时间大大缩短。通过吉布斯自由能的计算、活性氧物种的捕获实验、电子顺磁共振等方法，证明了在光催化氧化硫醚的反应过程中，同时存在超氧负离子自由基和单线态氧两个活性物种，从而加快了光催化氧化反应速率。该研究结果将对新型有机三重态光敏剂的分子结构设计以及在光催化有机合成反应中的应用起到一定的促进作用。

Fullerene-bodipy Dyads and Triad Showing Strong Visible Light Absorption as Photocatalysts in Photocatalytic Oxidation of Sulfides

Fullerene C₆₀-Bodipy dyads and triad were prepared with the Bodipy as visible light-harvesting antenna and the C₆₀ unit as the intramolecular spin conventer. The dyads and triad show strong visible light absorption and long-lived triplet excited states, and were used as triplet photosensitizers for photocatalytic oxidation of sulfides. The triad shows broadband visible light-absorption, which is different from the conventional triplet photosensitizers. The photophysical properties of the triplet photosensitizers were studied with steady state and time-resolved spectroscopies. The compounds were used for photocatalytic oxidation of sulfides. The photocatalytic activity was greatly improved with the new organic triplet photosensitizers as compared with that of the conventional photocatalysts, such as the Ru(Ⅱ) bipyridine complexes. With electrochemical data, calculation of the free energy changes of the electron transfer between the photosensitizers and the substrates, electron spin resonance (ESR), it was confirmed that both singlet oxygen and superoxide radical anion were involved in the photocatalytic cycles and the intermolecular electron transfer and triplet energy transfer were improved with these new photosensitizers which show strong visible light-absorbing long-lived triplet excited states. These studies will be helpful for future design of new triplet photosensitizers as well as the application of organic photosensitizers in photocatalytic organic reactions.