Metal Organic Framework

Review article
Joseph eiffe, JS, Chemistry
Title: Developments in Metal Organic Frameworks for utilization in Catalysis.
Abstract:
Metal organic frameworks (MOF’s) are crystalline materials comprised of metal centres co-ordinately connected to each other by poly dentate ligands. With the recent increase in research into MOF’s the interesting properties of these materials become apparent. Most notable of these properties are the very high specific surface area and very high porosity. These two properties make MOF’s interesting materials for catalysis. Developments on a number of methods have been made in making MOF’s catalytically active. These have ranged from the use of catalytically active metal nano partials located in the pores of the

4: (a) Crystal structure of rho-ZMOF (left) and schematic presentation of [H2TMPyP]4+ porphyrin ring enclosed in rho-ZMOF R-cage (right, drawn to scale). (b) Cyclohexane catalytic oxidation using Mn-RTMPyP as a catalyst at 65 ◦C.[14]
A similar method was used for the heterogenation of a cationic homogenous catalysts. Developed by Genna et al. the technique involves the cationic exchange of guest molecules in the framework of the MOF. The MOF was comprised of an anionic framework with stabilizing cations located in voids in the MOF. Upon addition of the cationic catalyst to a solution containing the host MOF a partial cationic exchange of the cationic catalysts and the indigenous cations occurred. It was found that up to 34% mol exchange occurred in the MOF.[15]
Comparing the MOF encapsulating catalysts, ZJU-28-[Rh(dppe)(COD)]BF4, to the free homogenous catalysts it was found that the two catalysts were had similar reactivity and turnover rate. It was found however that the heterogeneous variant of the catalysed could be isolated and recycled four times before there was minimal loss in reactivity. The homogenous variant however could only be used one additional time, this was was with only a further 200 addition turnovers by the catalyst. This was then followed by a total breakdown of the catalytic material.

With the majority of papers in the field been published in just the past 5 years a lot of research still has to be carried out in order for these materials to be used in industry. With all the advances in the past few years MOF still have yet to be able to compete with zeolite equivalent catalysts. It appears the key area of catalysis where MOF will play their role is in catalysis under mild conditions.
With their wide range of possible mechanisms for catalysis by MOF, or MOF derivatives, it appears that MOF will be able to act as viable catalysts for a whole host of reactions. With their activity and mechanism being able to be finely controllable by selection of metal nodes and ligand supports. The number of possible configurations of ligands and metal nodes the number of possible MOF appears endless. The capacity for MOF to act as catalysts is emerging to be in the areas of fine organic synthesis and enantioselective