A joint mechanism for singlet oxygen generation by diketone-anchored MIL-101: Exciton-mediated energy transfer and photosensitization

Post-synthetic modification with beta-diketone has been proven as an effective strategy to improve the visible light response activities of metal-organic frameworks (MOFs). Nevertheless, the effects of the anchored-diketones on the excitonic behaviors and photocatalytic mechanisms of MOFs are still unclear. Herein, two MOFs (MIL-101 with Cr-III and MIL-101 with Al-III) were employed as prototypical materials to further understand this post-synthetic modification strategy. Diketone anchoring could enhance the photocatalytic generation of singlet oxygen (O-1(2)) by the two MOFs in a joint mechanism: exciton-mediated energy transfer and photosensitization. Diketone anchoring induced triplet exciton was found playing an important role in the photocatalytic generation of O-1(2). The photosensitization of the anchored-diketone also played a key role in the photocatalytic generation of O-1(2). The results here provide a useful guidance for the development of MOFs-based photocatalysts and are helpful to realize the regulation of excitonic behaviors and photocatalytic mechanisms of MOFs.