Strategies to Incorporate Mesoporosity - Mesoporous Organic-Inorganic Non-Siliceous Hybrid Materials - page 32

Fig. 3.5 Schematic representation of the formation of highly crystalline MOF versus MOA.
Reprinted with permission from Ref. [ 29 ]. Copyright 2013, Nature Publishing Group
network of interconnected about 40-nm-sized microporous nanocrystallites.
Besides the intrinsic micropores, the prepared ZIF and HKUST-1 exhibited
aerogel-like textural interparticular voids from 2 to 100 nm, encompassing the
mesoporous and macroporous regions that were absent in the single crystal forms.
The crown ether molecules complex the Zn 2 + and Cu 2 + at first and then gradually
release the metal ions upon reaction with the organic ligands. The reduced nuclea-
tion and crystallization rates lead to improved crystallinity of the resultant MOFs.
Significantly, the pH of the template solutions influences the self-assembly of
block co-oligomers, the capture of metal ions, and the protonation/deprotonation
of the ligands.
A facile phosphate-mediated self-assembly methodology has been carried out
to prepare mesoporous nickel phosphate/phosphonate hybrid microspheres [ 33 ].
The hybrid microspheres are composed of not only crystalline nickel phosphate
but also amorphous nickel phosphonate (Fig. 3.6 ), and the formation of crystal-
line Ni 3 (PO 4 ) 2 nanoparticles played crucial roles in the formation of these hybrid
microspheres. When phosphoric acid and nickel salts were mixed under vigorous
stirring, uncountable Ni 3 (PO 4 ) 2 nanoparticles of a few nanometers were emerged
instantaneously. Nickel phosphonate clusters were formed after the addition of
ethylene diamine tetra(methylenephosphonic acid) (EDTMP) to react with the