Building a Pyrazole–Benzothiadiazole–Pyrazole Photosensitizer into Metal–Organic Frameworks for Photocatalytic Aerobic Oxidation

Abstract

Charge separation plays a crucial role in regulating photochemical properties and therefore warrants consideration in designing photocatalysts. Metal–organic frameworks (MOFs) are emerging as promising candidates for heterogeneous photocatalysis due to their structural designability and tunability of photon absorption. Herein, we report the design of a pyrazole–benzothiadiazole–pyrazole organic molecule bearing a donor–acceptor–donor conjugated π-system for fast charge separation. Further attempts to integrate such a photosensitizer into MOFs afford a more effective heterogeneous photocatalyst (JNU-204). Under visible-light irradiation, three aerobic oxidation reactions involving different oxygenation pathways were achieved on JNU-204. Recycling experiments were conducted to demonstrate the stability and reusability of JNU-204 as a robust heterogeneous photocatalyst. Furthermore, we illustrate its applications in the facile synthesis of pyrrolo­[2,1-a]­isoquinoline-containing heterocycles, core skeletons of a family of marine natural products. JNU-204 is an exemplary MOF platform with good photon absorption, suitable band gap, fast charge separation, and extraordinary chemical stability for proceeding with aerobic oxidation reactions under visible-light irradiation.

Building an emission library of donor–acceptor–donor type linker-based luminescent metal–organic frameworks

“…It should be noted that a similar MOF to HIAM-3004 was reported for photocatalytic aerobic oxidation when we prepared our manuscript, which further demonstrates the promising applications of these MOFs. 34 …”

“…It should be noted that a similar MOF to HIAM-3004 was reported for photocatalytic aerobic oxidation when we prepared our manuscript, which further demonstrates the promising applications of these MOFs. 34 A totally different crystal structure was obtained when the acceptor group was changed from benzo[c] [1,2,5]thiadiazole to 5,6-dimethylbenzo[c][1,2,5]thiadiazole for pyrazolate-based linkers. For HIAM-3006, a similar connection model to HIAM-3004 was observed where the Zn(II) cation is fully coordinated in a tetrahedral geometry with four nitrogen atoms from four DDPBT ligands.…”

Pyrazine functionalization to boost the antenna effect in rare-earth metal–organic frameworks for tetracycline detection

“…Due to their abundant pore metrics and surface chemistry, MOFs have been widely studied in host-guest recognition, LED lighting, catalysis, information storage and gas storage/separation, etc. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] As far as luminescence sensing is concerned, rare-earth MOFs (RE-MOFs) are promising candidates owing to their intriguing electronic/optical properties, intense luminescence emissions and high resistance to interference. [28][29][30][31][32] However, the production of RE-MOFs with characteristic RE luminescence is still serendipitous, and the limited hydrolytic stability of most RE-MOFs hinders their real-world applications in aqueous-medium environments.…”

Temperature- and solvent-induced reversible single-crystal-to-single-crystal transformations of TbIII-based MOFs with excellent stabilities and fluorescence sensing properties toward drug molecules

“…Metal–organic frameworks (MOFs) have potential application prospects in the fields of sensing, 1,2 catalysis, 3 magnetism, 4 proton conduction 5 and gas adsorption and separation 6,7 due to the abundant topological networks, 8 high specific surface area 9 and adjustable optical properties. 10 Single-crystal-to-single-crystal (SCSC) conversion is an effective way to reconstruct the structures of MOFs 11 accompanied by the changes of coordination bonds, dimensions and porosity.…”