Size and Function Influence Study on Enhanced Catalytic Performance of a Cooperative MOF for Mild, Green and Fast C-C Bond Formation
Tuning of pore function and size (surface area) are two key factors that play important roles in metal-organic-frameworks (MOFs) performance as a catalyst. The catalytic performance of two bulk and nanosized MOFs with different functional groups such as Brønsted base and Lewis acid were studied in line with catalyst sustainable development and green chemistry principles. Bifunctional imine decorated TMU-33, ([Cd3(BDC)3(OPP)(DMF)2].2DMA)n (TMU-33), (OPP:N,N'-(oxybis(4,1-phenylene)) bis(1-(pyridin-4yl) methanimine)), with adjustable structure and amine-functionalized TMU-40, [Zn(BDC)( L*)]. DMF, (L*: N1, N2-Bis (pyridin-4-ylmethylene) ethane-1,2-diamine), were evaluated in the C-C bonding forming reaction in the mild and green situation. The results show that nanosized samples of bifunctional TMU-33 which simultaneously have imine and the open metal sites have higher performance as Knoevenagel catalyst. Furthermore, among nanosized samples, the nanoplate TMU-33 with more access to open metal sites shows the highest catalytic activity without any side product in water, room temperature at 5 min, that confirms the Lewis acid is an effective catalyst for this reaction. The catalyst could be reused for at least three cycles without significant loss of its activity. The performance of the structure indicates that tuning of the functionality of MOFs can be a very promising route for the extension of green catalysts.