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to minimize the interfacial energy. Distinct from the high solubility of nickel
chloride, nitrate, and sulfate in water, nickel phosphate is insoluble. If phosphoric
acid was substituted by hydrochloric, nitric, and sulfuric acids, the resultant prod-
ucts were amorphous nickel phosphonate nanoparticles. The hybrid microspheres
could also be obtained when Na
2
HPO
4
, NaH
2
PO
4
, and Na
3
PO
4
were employed as
inorganic phosphors sources, suggesting that Ni
3
(PO
4
)
2
involved in the self-assem-
bly procedure. The selection of the right phosphonic precursors is considerably
significant to determine the resultant micromorphology. In this work, the tetrap-
hosphonic claw molecules containing pyridinic nitrogen could protonate in acid
environment and thus form zwitterions, which could contribute to the hydrogen-
bonding interactions between the phosphate nanoparticles and the slowly formed
phosphonates. A kind of biphosphonic acid (HEDP) without pyridinic nitro-
gen component was tried to substitute EDTMP to prepare hybrid microspheres,
but failed, signifying the positive roles of proper weak interaction. Another
N-containing phosphonic acid (bis(hexamethylene triamine penta(methylene phos-
phonic acid)), BHMTPMP) with similar molecular structure to EDTMP but longer
alkyl chains (-[CH
2
]
6
-) was used as well, and spherical nanoparticles were gained,
which might be due to that the strong hydrophobic interaction between the hexam-
ethylenetriamine bridges could disturb the intermolecular interactions and the self-
assembly process. The resultant nickel phosphate/phosphonate material presents
great potential in CO
2
capture and heavy metal ion removal.
Mesoporous even hierarchically porous non-siliceous hybrids could be obtained
through a self-assembly approach in the absence of any templates or surfactants.
No matter whether using linkage extension, microemulsion, or nanocrystal self-
assembly methodologies, they usually involve weak interactions among the hybrid
nanobuilding blocks. Other interactions such as hydrogen bonds, hydrophobicity-
hydrophobicity interactions, and
ˀ
-
ˀ
stacking can also direct the spontaneous
formation of mesoporous non-siliceous materials with fascinating porosity, struc-
tures, and stability, which are mainly dependent on the synthesis conditions. This
means that the synthesis processes are difficult to control to some extent. Solgel
chemistry presents an alternative route to synthesize mesoporous even hierarchical
porous hybrid materials, wherein the solgel processes are directly associated with
the precursor species and solvents.
3.2 Surfactant-Mediated Synthesis Strategy
Although surfactant- or template-free approaches have been proven to be valuable
methods to obtain hybrid organic-inorganic materials presenting porosity from
micropores to macropores, these methods cannot afford the valid capability to
adjust the porosity, texture, and even morphologies on demand. As to some kinds
of potential applications, such as separation and recognition of large molecules,
catalysts and catalyst supports, and dye adsorption, the existence of mesopores
is much more preferable than micropores and macropores to some certain extent.
The use of supramolecular templates to synthesize ordered mesoporous materials
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