Metal–Organic Frameworks for the Exploitation of Distance between Active Sites in Efficient Photocatalysis

Abstract

Discoveries of the accurate spatial arrangement of active sites in biological systems and cooperation between them for high catalytic efficiency are two major events in biology. However, precise tuning of these aspects is largely missing in the design of artificial catalysts. Here, a series of metal–organic frameworks (MOFs) were used, not only to overcome the limit of distance between active sites in bio‐systems, but also to unveil the critical role of this distance for efficient catalysis. A linear correlation was established between photocatalytic activity and the reciprocal of inter active‐site distance; a smaller distance led to higher activity. Vacancies created at selected crystallographic positions of MOFs promoted their photocatalytic efficiency. MOF‐525‐J33 with 15.6 Å inter active‐site distance and 33 % vacancies exhibited unprecedented high turnover frequency of 29.5 h−1 in visible‐light‐driven acceptorless dehydrogenation of tetrahydroquinoline at room temperature.

A Perspective Review on N-Heterocycles as Liquid Organic Hydrogen Carriers and Their Hydrogenation/Dehydrogenation Catalysts

“…This porphyrin is an important active site for redox reactions in biological systems, and the high catalytic activity is attributed to MOF active site distance modulation, resulting in a short mutual active site distance for PCN-233. 210 Graphitic carbon nitride (g-C 3 N 4 ) can be used as a mild metal-free photocatalyst for hydrogen precipitation under visible light. Su developed a mesoporous graphitic carbon nitride (mpg-C 3 N 4 ) catalyst capable of catalyzing the dehydrogenation of quinolines from THQ under visible light irradiation at 100 °C for 4.5 h. The catalyst is stable and reusable, and does not require the use of any metal derivative or organic oxidant for catalysis.…”

Metal-porphyrinic framework nanotechnologies in modern agricultural management

“…5 74 and 6. 75 The most used metal-porphyrinic frameworks are PCN-222 and PCN-224 (free base or metalated versions of TCPP 4À , MTCPP 4À ). 76 The center-to-center distances defining the pore size range from B10 to B18 Å.…”

Oxidation of N‐Alkyl(iso)quinolinium Salts Over TEMPO@Metal‐Organic Framework Heterogeneous Photocatalyst†

“…As an emerging class of porous crystalline materials, metal‐organic frameworks (MOFs) provide an ideal molecular platform to orderly assemble photosensitizing organic ligands with metal‐containing nodes (also known as secondary building units, or SBUs), which exhibited a great potential for heterogeneous photosynthesis [9–19] . In particularly, synergistic catalysis can be realized in MOFs by integrating the photosensitizing sites with catalysts or cocatalysts due to their highly tunable structures/components [12–14,20,21] .…”