Properties and Factors Affecting the Preparation of Metal-Organic Frameworks

Abstract

Metal-organic frameworks (MOFs) are created by the linkage of metal nodes and organic linkers, presenting unlimited tuneability for component diversity and structural hierarchy. Guided by the reticular synthesis approach, more than 90,000 MOFs have been synthesized and 500,000 are predicted. However, the quest for the synthesis of MOFs with preferred sizes, morphologies, and hierarchical assemblies is still open. It requires careful selection of synthetic strategies and reaction parameters, as controlled synthesis is vital for tuning a range of behaviors for different MOFs. The present chapter highlights major parameters that influence MOF synthesis. The growth of MOF can be considered as a block-building game dominated by the assembling strategies that include positional isomeric effect and substituent effect, are discussed in detail. The role of flexible spacers influencing the interpenetration in 3D MOF causing the distortion in the structure is explained. Choice of an appropriate secondary building unit (SBU) has a special significance in predicting MOF topologies and the cluster of bridged coordinating ligands enhancingtheir robustness through the superior physical properties are also discussed. An overview of secondary building units designed over metal-oxygen linkage and W-Cu-S–based clusters with varied coordination networks determining the directionality is provided. Towards the end, the effect of various chemical and physical factors, namely solvent, reaction temperature, and pH over the anchoring traits of the coordinating ligand, along with the network architecture of the developed MOF are discussed.