Self-Assembled Boronic Ester Cavitand Capsule as a Photosensitizer and a Guard Nanocontainer against Photochemical Reactions of 2,6-Diacetoxyanthracene

The optical properties of 2,6-diacetoxyanthracene 4 encapsulated in the self-assembled boronic ester cavitand capsule 3 in C(6)H(6) are described. Upon excitation at 285 nm, the encapsulated 4 showed strong fluorescence emission as a result of the energy transfer from the excited 3 to the encapsulated 4, while 4 alone in C(6)H(6) exhibited very weak emission. Upon photoirradiation at 365 nm, the encapsulated 4 also showed strong fluorescence emission and remained almost intact, whereas 4 alone in C(6)H(6) gradually underwent photodimerization and photooxygenation to afford photodimers 5 and 5' and 9,10-anthraquinone 6 via 9,10-endoperoxide 7, respectively. Thus, the capsule 3 serves as a photosensitizer for the encapsulated 4 as well as a guard nanocontainer to protect against the photochemical reactions of 4.

描述了封装在苯（C₆H₆）中自组装硼酸酯穴状配体胶囊3内的2,6 - 二乙酰氧基蒽4的光学性质。在285nm激发时，由于从激发态的3到封装的4发生能量转移，封装的4显示出强荧光发射，而在苯中单独存在的4则发射非常微弱。在365nm光照射下，封装的4也显示出强荧光发射且几乎保持完整，然而在苯中单独存在的4逐渐发生光二聚和光氧化，分别通过9,10 - 内过氧化物7生成光二聚体5和5′以及9,10 - 蒽醌6。因此，胶囊3对于封装的4起到光敏剂的作用，同时也是一个保护纳米容器，防止4发生光化学反应。