Confinement of Organic Dyes in UiO-66-Type Metal-Organic Frameworks for the Enhanced Synthesis of [1,2,5]Thiadiazole[3,4-g]benzoimidazoles

Organicdyes as non-noble metal photosensitizers have attractedincreasing attention due to their environmental friendliness and sustainabilitybut suffer from fast deactivation and low stability. Here, we reporteda fruitful strategy by the confinement and stabilization of visiblelight-active signal unit organic dyes within the metal-organicframeworks (MOFs) and developed a series of heterogeneous photocatalystsdye@UiO-66s [dye = fluorescein (FL)/rhodamine B (RhB)/eosin Y (EY),UiO-66s = UiO-66, and Bim-UiO-66]. It has been demonstrated that theencapsulated dyes can effectively sensitize MOF hosts and dominatethe band structures and photocatalytic activities of dye@UiO-66s regardlessof the ligand functionalization of MOFs. Photocatalytic experimentsshowed that these dye@UiO-66s exhibit enhanced activities relativeto free dyes and among them, FL@Bim-UiO-66 displays excellent efficienciestoward the green synthesis of new carbon-bridged annulations, [1,2,5]thiadiazole[3,4-g]benzoimidazoles in the yield of up to 98% at room temperaturewith outstanding stability and reusability. Furthermore, the intramolecularcyclization intermediate was captured and characterized by the single-crystalX-ray diffraction analysis.

Automated summary

In this study, a new heterogeneous photocatalyst dye@UiO-66s was developed by confining and stabilizing organic dyes within metal-organic frameworks. The encapsulated dyes effectively sensitize the MOF hosts and dominate the band structures and photocatalytic activities, resulting in enhanced catalytic performance and stability.