Syntheses of MOFs

Figure 11.2 illustrates some organic linkers used in the synthesis of MOFs. 

The crystallization process occurring during the solvothermal synthesis of MOF materials is sometimes regarded as an esterification-type reaction. Justify such an analogy. 

The synthesis of MOFs usually requires the pores or channels to be occupied with solvent molecules and sometimes also with unreacted, excess linkers. These molecules should be removable or exchangeable by other solvent or gas molecules... 

The synthesis of MOFs offers enormous scope for the realisation of highly impressive and very useful materials properties. In combining the versatility and diversity of coordination chemistry, organic chemistry and... 

While in situ synchrotron PXRD measurements are proven as an invaluable tool for monitoring the course of mechanochemical synthesis of MOFs and API... 

A very wide range of di-, tri- and tetra-carboxylic acids have been used in the synthesis of MOFs. Selected examples are shown in Figure 2.29, but a more... 

Yaghi et have taken the approach using trimeric building blocks a stage further with their synthesis of MOF-500, in which trimeric iron carboxylate units similar to those found in MlL-88, -100 and -101, but partially terminated by coordinated sulfate units that remain during the synthesis, are connected by coordination of the iron atoms in two further, hierarchical levels of complexity... 

In the synthesis of MOFs, varions methods/strategies have been employed, including solvent evaporation or diffusion, hydrothermal, solvothermal, using ionic liquids, electrochemistry, mechanochemistry, and ultrasonic methods [28]. And new ones are being explored with the development of MOFs field. Particularly, high-throughput screen has also been used in finding new MOFs materials [36, 37]. 

Lu CM, Liu J, Xiao KF et al (2010) Microwave enhanced synthesis of MOF-5 and its CO2 capture ability at moderate temperatures across multiple capture and release cycles. Chem Eng J 156 465-470... 

The IRMOFs [Zn40(00C-(S)-C00)3] thus obtained all have the same primitive cubic structure sketched in Fig. 30.3, with three series of identical perpendicular channels whose free diameters are directly related to the dimensions of the spacers, provided that no interpenetration occurred [7]. This was certainly one of the best results in the designed synthesis of MOFs, evidencing the value of the researcher s imagination, pursued with the aim to obtain a series of derivatives having structural properties directly related to the dimensions of the spacers used. 

Jung DW, Yang DA, Kim J et al (2010) Facile synthesis of MOF-177 by a sonochemical method using l-methyl-2-pyrrolidinone as a solvent. Dalton Trans 39 2883-2887... 

Figure 7.10 Schematic of a capillary-based droplet microreactor for the continuous synthesis of MOF hollow microsphere. (Reproduced from Ref. [78].)...

Traditionally, the synthesis of MOFs follows a solvothermal route, heating a ligand (typically in protonated form) and metal salt mixture in solvents such as dimethylformamide (DMF) for hours or up to several days. However, this often produces small amounts of the desired crystals (ca. 1 g or less) and the amount of solvent required limits feasible scale-up. Other methods have been examined, such as sonochemical and microwave assisted synthesis, with both of these methods and others covered in an in-depth review by Meek. These methods are outside the scope of this report, which is limited to an electrosynthetic focus. 

The first known instance of the synthesis of MOFs through an electrochemical route was performed by Mueller and coworkers, who pioneered a technique of anodic dissolution of the cation of a MOF metal centre within a solution of an organic bridging ligand and conducting salt, resulting in formation of, in this case, Cu-MOF (also known as HKUST-1 [Cu3(btc)2], btc = 1,3,5-benzenetricarboxylate, see Fig. 2) without side... 

Once the richness of the field was discovered, it was necessary to rationalize the synthesis of MOFs to provide tailor-made architectures. At the beginning, the reticular chemistry of the augmented net concept of O Keeffe et al. [56] was nicely applied for defining the chemical and topological rules governing this possible design. The derived structures of MOF-5 [4] provide the most famous example of this approach. 

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