A major goal of metal–organic framework (MOF) research is the expansion of pore size and volume. Although many approaches have been attempted to increase the pore size of MOF materials, it is still a challenge to construct MOFs with precisely customized pore apertures for specific applications. Herein, we present a new method, namely linker labilization, to increase the MOF porosity and pore size, giving rise to hierarchical-pore architectures. Microporous MOFs with robust metal nodes and pro-labile linkers were initially synthesized. The mesopores were subsequently created as crystal defects through the splitting of a pro-labile-linker and the removal of the linker fragments by acid treatment. We demonstrate that linker labilization method can create controllable hierarchical porous structures in stable MOFs, which facilitates the diffusion and adsorption process of guest molecules to improve the performances of MOFs in adsorption and catalysis.
The incorporation
of large π-conjugated ligands into metal–organic
frameworks (MOFs) can introduce intriguing photophysical and electrochemical
properties into the framework. However, these effects are often hindered
by the strong π–π interaction and the low solubility
of the arylated ligands. Herein, we report the synthesis of a porous
zirconium-based MOF, Zr6(μ3-O)4(μ3-OH)4(OH)6(H2O)6(HCHC) (PCN-136, HCHC = hexakis(4-carboxyphenyl)hexabenzocoronene),
which is composed of a hexacarboxylate linker with a π-conjugated
hexabenzocoronene moiety. Direct assembly of the Zr4+ metal
centers and the HCHC ligands was unsuccessful due to the low solubility
and the unfavorable conformation of the arylated HCHC ligand. Therefore,
PCN-136 was obtained from aromatization-driven postsynthetic annulation
of the hexaphenylbenzene fragment in a preformed framework (pbz-MOF-1)
to avoid π–π stacking. This postsynthetic modification
was done through a single-crystal-to-single-crystal transformation
and was clearly observable utilizing single -crystal X-ray crystallography.
The formation of large π-conjugated systems on the organic linker
dramatically enhanced the photoresponsive properties of PCN-136. With
isolated hexabenzocoronene moieties as photosensitizers and Zr–oxo
clusters as catalytic sites, PCN-136 was employed as an inherent photocatalytic
system for CO2 reduction under visible-light irradiation,
which showed increased activity compared with pbz-MOF-1.
Copper-based compounds are promising entities for target-specific next-generation anticancer and NSAIDS therapeutics.
In lieu
of this, benzimidazole scaffold plays an important role, because of their wide variety of potential functionalizations and coordination modes. Herein, we report three copper complexes
1
–
3
with benzimidazole-derived scaffolds, a biocompatible molecule, and secondary ligands viz, 1–10-phenanthroline and 2,2′-bipyridyl. All the copper complexes have been designed, synthesized and adequately characterized using various spectroscopic techniques.
In-vitro
, human serum albumin (HSA) binding was also carried out using fluorescence technique and
in-silico
molecular modeling studies, which exhibited significant binding affinities of the complexes with HSA. Furthermore, copper complexes
1
–
3
were tested for biological studies, i.e., anticancer as well as NSAIDS.
In vitro
cytotoxicity results were carried out on cultured MCF-7 cell lines. To get the insight over the mechanism of action, GSH depletion and change in lipid peroxidation were tested and thus confirmed the role of ROS generation, responsible for the cytotoxicity of the complexes
1
–
3
. Moreover, the copper complexes
1
–
3
were tested for potential to act as NSAIDS on albino rats and mice in animal studies
in-vivo
. Additionally, we also predicted the mechanism of action of the copper complexes
1
–
3
using molecular modeling studies with COX-2 inhibitor.
Crystal engineering of metal−organic frameworks (MOFs) has allowed the construction of complex structures at atomic precision, but has yet to reach the same level of sophistication as organic synthesis. The synthesis of complex MOFs with multiple organic and/or inorganic components is ultimately limited by the lack of control over framework assembly in one-pot reactions. Herein, we demonstrate that multi-component MOFs with unprecedented complexity can be constructed in a predictable and stepwise manner under simple kinetic guidance, which conceptually mimics the retrosynthetic approach utilized to construct complicated organic molecules. Four multi-component MOFs were synthesized by the subsequent incorporation of organic linkers and inorganic clusters into the cavity of a mesoporous MOF, each composed of up to three different metals and two different linkers. Furthermore, we demonstrated the utility of such a retrosynthetic design through the construction of a cooperative bimetallic catalytic system with two collaborative metal sites for three-component Strecker reactions.
Mixed-linker strategy is a promising way to construct multifunctional metal–organic frameworks (MOFs). In this review, we demonstrate the recent developments, discussions and challenges related to the preparation and applications of four types of mixed-linker MOF materials.
A novel porous material was realized for highly efficient post-combustion CO2 capture with high CO2 adsorption capacity, high selectivity and moderate heat of adsorption, mainly attributed to the suitable pore size and dual functionalities.
Epitaxial growth of MOF-on-MOF composite is an evolving research topic in the quest for multifunctional materials. In previously reported methods, the core-shell MOFs were synthesized via a stepwise strategy that involved growing the shell-MOFs on top of the preformed core-MOFs with matched lattice parameters. However, the inconvenient stepwise synthesis and the strict lattice-matching requirement have limited the preparation of core-shell MOFs. Herein, we demonstrate that hybrid core-shell MOFs with mismatching lattices can be synthesized under the guidance of nucleation kinetic analysis. A series of MOF composites with mesoporous core and microporous shell were constructed and characterized by optical microscopy, powder X-ray diffraction, gas sorption measurement, and scanning electron microscopy. Isoreticular expansion of microporous shells and orthogonal modification of the core was realized to produce multifunctional MOF composites, which acted as size selective catalysts for olefin epoxidation with high activity and selectivity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.