structure, and structural phase selectivity as well as narrow particle size distribution
(Lee et al. 2013). The microwave-assisted in the preparation of MOFs employs
heating a substrate mixture in a suitable solvent with microwave radiation for an
hour in order to produce nanosized crystals (Fig. 10.5b). The quality of the crystal
materials generated by microwave-assisted technique are similar to the one prepared
by the ordinary solvothermal route, but microwave-assisted method achieved the
preparation process very faster (Li and Yang 2007).
10.4.3.3 Mechanochemical Process
Mechanochemical method is one of the solvent-free synthetic routes employed
to prepare MOF structure using only metal salt and organic linker without any
solvent (Fig. 10.5c). This method uses two reaction steps, where it involves the
mechanical breakdown of intramolecular bonds followed by chemical transformation (Song et al. 2006). It has several advantages over other method because
chemical reactions can take place at room temperature, qualitative and quantitative
yield of product are obtained in less than 20 min. In most cases, preference of
the source of metal ions were metal oxides instead of metal salts because metal
oxide produce in water as by-product during preparation (Wang and Hu 2018).
In addition, it was shown in recent years that the mechanochemical method has
been efficiently applied for the fast synthesis of MOFs with the help of liquidassisted grinding (LAG). The LAG is used as a structure directing agent by addition
of small amount of solvent into a solid reaction mixture. Moreover, the synthetic
route was advanced to prepare pillared-layered structured MOFs using ion-and
liquid assisted grinding (ILAG) (Tan et al. 2017). However, the method is limited
to explicit MOF types which cannot yield large amount of product (Langmi et al.
2013).
10.4.3.4 Post Synthesis
MOFs has ability to combine with compound of additional functional groups into
MOF framework, hence producing a different of MOF structures with varied of
functional groups still maintaining the same topology (Volkova et al. 2014). Nevertheless, the introduction of functional groups onto the MOF structure remains to be
a challenging problem during preparation method. This setback may be addressed by
employing a post-synthesis modification (PSM) route. The PSM is one of surface
modification or functionalization of MOF structure after their formation (Fig. 10.6).
The addition of functional groups onto MOF structure can be obtained by
noncovalent, coordinative or covalent interactions (Yuan et al. 2015; Kim et al.
272
T. C. Maponya et al.
(Lee et al. 2013). The microwave-assisted in the preparation of MOFs employs
heating a substrate mixture in a suitable solvent with microwave radiation for an
hour in order to produce nanosized crystals (Fig. 10.5b). The quality of the crystal
materials generated by microwave-assisted technique are similar to the one prepared
by the ordinary solvothermal route, but microwave-assisted method achieved the
preparation process very faster (Li and Yang 2007).
10.4.3.3 Mechanochemical Process
Mechanochemical method is one of the solvent-free synthetic routes employed
to prepare MOF structure using only metal salt and organic linker without any
solvent (Fig. 10.5c). This method uses two reaction steps, where it involves the
mechanical breakdown of intramolecular bonds followed by chemical transformation (Song et al. 2006). It has several advantages over other method because
chemical reactions can take place at room temperature, qualitative and quantitative
yield of product are obtained in less than 20 min. In most cases, preference of
the source of metal ions were metal oxides instead of metal salts because metal
oxide produce in water as by-product during preparation (Wang and Hu 2018).
In addition, it was shown in recent years that the mechanochemical method has
been efficiently applied for the fast synthesis of MOFs with the help of liquidassisted grinding (LAG). The LAG is used as a structure directing agent by addition
of small amount of solvent into a solid reaction mixture. Moreover, the synthetic
route was advanced to prepare pillared-layered structured MOFs using ion-and
liquid assisted grinding (ILAG) (Tan et al. 2017). However, the method is limited
to explicit MOF types which cannot yield large amount of product (Langmi et al.
2013).
10.4.3.4 Post Synthesis
MOFs has ability to combine with compound of additional functional groups into
MOF framework, hence producing a different of MOF structures with varied of
functional groups still maintaining the same topology (Volkova et al. 2014). Nevertheless, the introduction of functional groups onto the MOF structure remains to be
a challenging problem during preparation method. This setback may be addressed by
employing a post-synthesis modification (PSM) route. The PSM is one of surface
modification or functionalization of MOF structure after their formation (Fig. 10.6).
The addition of functional groups onto MOF structure can be obtained by
noncovalent, coordinative or covalent interactions (Yuan et al. 2015; Kim et al.
272
T. C. Maponya et al.