Redox Metal–Organic Framework for Photocatalytic Organic Transformation: The Role of Tetrazine Function in Radical-Anion Pathway

Abstract

Linker functionalization is a practical strategy to extend the applications of metal–organic frameworks (MOFs) in various fields. Here, this strategy is applied to synthesize a tetrazine-functionalized MOF [TMU-34(-2H), formulated [Zn(OBA) (DPT)0.5]·DMF; H2OBA and DPT are 4,4′-oxybis(benzoic acid) and 3,6-di(pyridin-4-yl)-1,2,4,5-tetrazine] for efficient photocatalytic synthesis of disulfides and benzimidazoles with maximum conversion after 90 and 120 min, respectively. The photocatalytic activity of TMU-34(-2H) originates from the electronic properties of tetrazine function, including absorption in the visible region and photogenerated redox activity. In the proposed mechanism, neutral tetrazine sites are excited upon visible-light irradiation. Then, photoexcited tetrazine sites accept one electron from the reactants leading to generation of tetrazine radical anions as electron mediator sites. Finally, the electrons transfer from the tetrazine radical anion sites to other substrates in the reaction. The results show that organic chromophores, such as tetrazine, are good candidates for extension of application of MOFs in visible-light photocatalysis.

Incorporating a D–A–D-Type Benzothiadiazole Photosensitizer into MOFs for Photocatalytic Oxidation of Phenylsulfides and Benzylamines

“…As depicted in Figures b–d and S19, a wide absorption range was observed for 1 or 2 , suggesting a high visible light adsorption efficiency. The band gap energies ( E g ) of 1-Co , 1-Zn , 2-Gd , and 2-Tb were estimated to be about 1.91, 2.40, 2.37, and 2.38 eV, respectively, based on the Tauc curves (Figures b–d and S19a inset), indicating the potential application as semiconductors in the field of visible light-driven photocatalysis . Moreover, the Mott–Schottky curves of 1-Co , 1-Zn , 2-Gd , and 2-Tb were carried out at a frequency of 500 Hz, and the flat-band potentials were calculated to be −0.47, −0.54, −0.58, and −0.46 V (vs Ag/AgCl), respectively (Figures e and S19), and these slope curves also indicated the features of n-type semiconductors.…”

Advanced bioactive nanomaterials for biomedical applications

“…Metal‐organic frameworks (MOFs) are a class of inorganic‐organic hybrid nanomaterials built from metal ions bridged by organic linkers. [ 59,60 ] MOFs can degrade rapidly and release their metal ions or organic linkers in acid conditions. Zhang et al.…”

Application of Metal‐Organic Frameworks in Imaging‐Guided Therapy

“…Metal‐organic frameworks (MOFs) are unique and helpful classes of porous coordination polymers (CPs), made by linking inorganic (metal centres/clusters) and organic (organic linkers) units by strong coordination bounds [1–7] . The inorganic units in MOFs contain alkali metals, transition metals, lanthanides and actinides.…”