Zhichao Shao

Solvent-Induced Assembly of Sliver Coordination Polymers (CPs) as Cooperative Catalysts for Synthesizing of Cyclopentenone[b]pyrroles Frameworks

A series of solvent-induced Ag-based coordination polymers (CPs) (1-3), which were synthesized by regulating the size, shape, and polarity of solvent molecules (EtOH, iPrOH, 1,4-dioxane) as structure-directing agents, has been used as heterogeneous catalysts to explore how the metal-metal bonds could serve as cooperative catalysis for tandem acylation-Nazarov cyclization reaction to prepare cyclopentenone[b]pyrroles frameworks. Structural conversions from a three-dimensional (3D) framework of 1 to the structure of 2 with Ag-Ag-Ag bonds and to the two-dimensional (2D) framework of 3 with Ag-Ag bonds, arising from the different sizes, shapes, and polarities of the solvent molecules, were observed. Futhermore, the effective cooperative catalysis for tandem acylation-Nazarov cyclization reaction has been evidenced by the significantly transformed connection modes of Ag-Ag interactions in 1-3. As a result, the unique structural characteristics of 2, especially containing the Ag-Ag-Ag bonds, endow 2 with intact multinuclear reaction pathways and well-defined multinuclear platforms that can execute tandem acylation-Nazarov cyclization reaction through the cooperative effect of Ag-Ag-Ag interactions during the catalytic process.

Efficient Catalytic Performance for Acylation-Nazarov Cyclization Based on an Unusual Postsynthetic Oxidization Strategy in a Fe(II)-MOF

A rare example of SC-SC triggered by Cu2+ heterogeneous oxidation was demonstrated in a Fe(II)-based MOF {[FeII3(L)2(H2O)6]·3H2O} n (1), which occurred a slow conversion into an oxidized MOF 2 ({[FeIII3(L)2(H2O)6]·3(OH)} n) with retention of single crystallinity. The FeII → FeIII progress of the reaction oxidation was proved by single crystal XRD, PXRD, XPS, 57Fe Mössbauer spectroscopy, and UV-vis. We used 1 and 2 as catalysts to catalyze the tandem Nazarov cyclization, and the results show that acylation products were only harvested when 1 was a catalyst, while the oxidized transformer 2 lead mainly to the formation of cyclization products under identical conditions. Through the test of different substrates, 2 can be a good heterogeneous catalyst candidate for the formation of cyclopentenone[ b] benzenes. This work provides a new way to design efficient and hard-synthesized heterogeneous catalyst materials.