Aqueous-Phase Synthesis of MesoporousZr-Based MOFs Templated
Ke Li, Shaoliang Lin, Yongsheng Li, Qixin Zhuang,and Jinlou Gu*
Abstract: Zr-based mesoporous metal–organic frameworks
(mesoMOFs) with uniform mesochannels and crystallized
microporous framework were constructed in awater-based
system using amphoteric surfactants as templates.Aqueous-
phase synthesis guaranteed the formation of rod-shaped
surfactant micelles.Meanwhile,the carboxylate groups of
amphoteric surfactants provided the anchoring to bridge Zr-
oxoclusters and surfactant assemblies.Asaresult, the directed
crystallization of MOFs proceeded around cylindrical micelles
and the hierarchical micro- and mesostructure was produced.
The dimensions of mesopores were easily tailored by changing
the alkyl chain length of the applied surfactants.The included
surfactant was effectively extracted thanks to the exceptional
stability of the obtained Zr-based mesoMOFs.The almost
complete occupation of the mesopore by cytochrome cexem-
plifies the accessibility of the mesochannels, suggesting the
potential applications of the obtained mesoMOFs with bulky
Metal–organic frameworks (MOFs), which are assembled
from organic ligands and metal ions or clusters,are booming
as aclass of fascinating crystalline materials.They feature
well-defined pore geometry,high surface area, and diverse
framework composition. By virtue of these merits,MOFs
hold great promise in avariety of potential applications.
However,most of the reported MOFs are restricted to the
microporous regime.The small pore size would slow down
mass transfer and prevent large guest molecules from
accessing the active sites inside ahost MOF.
the construction of MOFs with larger interconnected pores is
indispensable for applications with bulky molecules.
Some effort has been devoted to building mesoporous
MOFs (mesoMOFs). Pore channel expansion using elongated
ligands has been widely adopted, but instability upon solvent
removal and interpenetration of the structures were almost
Adefect-formation strategy has been also
proposed to create large voids,but unfortunately,the uneven
void size and random void arrangement might still restrict
Thetemplate method is frequently utilized
for the preparation of mesoporous silica since it provides
facile control over the geometry of the produced mesopore.
This was recently extended for the construction of meso-
MOFs and led to encouraging achievements.
instable pore structure of MOFs might be subject to collapse
upon removing the template agent.
template agent occasionally interferes with the formation of
MOF crystals,which might cause partial amorphization of
Keeping these pros and cons in
mind, we intend to develop arational surfactant self-assembly
strategy to retain the merits of the template approach while
avoiding the issues mentioned above.
Herein, we demonstrate our idea to elaborate such
mesoMOFs,which possess uniform mesochannels and
awell-crystallized microporous framework with geometry
complementary to that of surfactant self-assemblies.Addi-
tionally,the dimensions of continuous mesopores could be
easily tailored by changing the alkyl chain length of the
applied surfactants.Furthermore,the obtained mesoMOFs
exhibit exceptional stability so that the included surfactant
could be effectively extracted upon treatment with acidic
Thekey design element in our strategy is the utilization of
amphoteric surfactants,namely cocamidopropyl betaine
(CAPB) or oleyl amidopropyl betaine (OAPB), as atemplate
to construct mesoMOFs.There is aconsensus that the
interaction between the MOF precursor and surfactant is
critical for the successful growth of mesoMOFs directed by
Aweak interaction would make ligands and
metallic salts crystallize preferentially despite the surfactants.
Theamphoteric surfactants have acarboxylate functionality
and quaternary ammonium as the hydrophilic head group
(Scheme 1). Thecarboxylate functionality permits strong
bonding with metal clusters in MOFs,meanwhile,the
quaternary ammonium group imparts high solubility for the
otherwise insoluble fatty acid.
tional characteristic means that the amphoteric surfactant can
serve not only as atemplate but also acoordinating agent,
chemically attaching to the metal precursor during the self-
assembling process,which would effectively avoid the phase
Scheme 1. Chemical structure of the applied amphoteric surfactants,
CAPB and OAPB.
[*] Dr.K.Li, Prof. S. Lin, Prof. Y. Li, Prof. Q. Zhuang, Prof. J. Gu
Key Laboratory for Ultrafine Materials of Ministry of Education
School of Materials Science and Engineering
East China University of Science and Technology
Shanghai 200237 (China)
Supportinginformation and the ORCID identification number(s) for
the author(s) of this article can be found under:
3439Angew.Chem. Int.Ed. 2018, 57,3439 –3443 2018 Wiley-VCH Verlag GmbH &Co. KGaA, Weinheim