Sequentially Regulating the Structural Transformation of Copper Metal-Organic Frameworks (Cu-MOFs) for Controlling Site-Selective Reaction.

Regulating atomically precise sites in catalysts to achieve site-selective reactions is remarkable but challenging. In this work, a convenient and facile solid-gas/liquid reaction strategy was used to construct controllable active sites in metal-organic frameworks (MOFs) to guide an orientation site-selective reaction. A flexible Cu I -MOF- 1 with dynamics originating from an anionic and tailorable framework could undergo a reversible structural transformation to engineer a topologically equivalent mixed-valent Cu I Cu II -MOF- 2 via a solid-gas/liquid oxidation/reduction process. More importantly, Cu I -MOF- 1 and Cu I Cu II -MOF- 2 could further execute the solid-gas/liquid reaction under ammonia vapor/solution to generate Cu II -MOF- 3 . Furthermore, the transformation from Cu I -MOF- 1 to Cu I Cu II -MOF- 2 and Cu II -MOF- 3 served as controllable catalysts to facilitate site-selective reactions to realize direct C-N bond arylations. The results demonstrated that Cu I -MOF- 1 and Cu II -MOF- 3 possessed well-defined platforms with uniformly and accurately active sites to attain a "turn-on/off" process via different reaction routes, providing the desired site-selective ring-opening products.