Ultrasound-assisted synthesis of two new fluorinated metal-organic frameworks (F-MOFs) with the high surface area to improve the catalytic activity

Micro- and nano-structures of two zinc(II) based fluorinated metal-organic frameworks (F-MOFs) [Zn-2(hfipbb)(2)(4-bpdh)].(DMF)(0.5) (TMU-55) and [Zn-2(hfipbb)(2)(4-bpdb)].(DMF)(2)(HTMU-55) with micro- and nanorods and nanospheres morphology were prepared via sonochemical route under ultrasonic irradiation without any surfactants at room temperature. These new micro and nano-structures were characterized by different techniques. To examine the effect of synthesis method on the porosity of the frameworks N-2 adsorption (BET analysis) was applied. The influence of sonication time and various concentrations of initial reagent on the morphology and size of the F-MOFs nanostructures were investigated. The results indicated that by increasing the time of ultrasonic radiation and concentration, smaller nanostructures form and morphological changes occurred. These two frameworks with the presence of hydrophobic fluoro groups near the basic reaction center in the F-MOFs are interesting candidates as an efficient catalyst in the Henry reaction for a comparative catalytic study. This investigation indicates the important role of the F-MOFs nanostructures synthesized by the ultrasonic method with the high surface area as heterogeneous catalysts with remarkable catalytic activity compared with other MOFs.