Construction of thermally and chemically robust metal−organic frameworks (MOFs) is highly desirable for postcombustion CO 2 capture from flue gas containing water vapor and other acidic gases. Here we report a strategy based on appending amino groups to the triazolate linkers of MOFs to achieve exceptional chemical stability against aqueous, acidic, and basic conditions. These MOFs exhibit not only CO 2 /N 2 thermodynamic adsorption selectivity as high as 120 but also CO 2 /H 2 O kinetic adsorption selectivity up to 70, featuring distinct adsorptive sites at the channel center for CO 2 and at the corner for H 2 O, respectively. The best performing MOF in this series features low regeneration energy, high CO 2 capture utility under humid conditions, and decent cycling performance for mimic flue gas.M etal−organic frameworks (MOFs) are prominent solid adsorbents that combine well-defined adsorptive sites, fine-tuned pore sizes, and decorated interior functionalities to achieve strong binding affinity, high selectivity, large capacity, and low regeneration energy for CO 2 capture. 1−3 However, with respect to practical postcombustion capture, concerns arise from the competitive adsorption of H 2 O against CO 2 4
A major challenge in material design is to couple nanoscale molecular and supramolecular events into desired chemical, physical, and mechanical properties at the macroscopic scale. Here, a novel self‐assembled DNA crystal actuator is reported, which has reversible, directional expansion and contraction for over 50 μm in response to versatile stimuli, including temperature, ionic strength, pH, and redox potential. The macroscopic actuation is powered by cooperative dissociation or cohesion of thousands of DNA sticky ends at the designed crystal contacts. The increase in crystal porosity and cavity in the expanded state dramatically enhances the crystal capability to accommodate/encapsulate nanoparticles/proteins, while the contraction enables a “sponge squeezing” motion for releasing nanoparticles. This crystal actuator is envisioned to be useful for a wide range of applications, including powering self‐propelled robotics, sensing subtle environmental changes, constructing functional hybrid materials, and working in drug controlled‐release systems.
Sequence-selective recognition of
DNA duplexes is important for
a wide range of applications including regulating gene expression,
drug development, and genome editing. Many small molecules can bind
DNA duplexes with sequence selectivity. It remains as a challenge
how to reliably and conveniently obtain the detailed structural information
on DNA–molecule interactions because such information is critically
needed for understanding the underlying rules of DNA–molecule
interactions. If those rules were understood, we could design molecules
to recognize DNA duplexes with a sequence preference and intervene
in related biological processes, such as disease treatment. Here,
we have demonstrated that DNA crystal engineering is a potential solution.
A molecule-binding DNA sequence is engineered to self-assemble into
highly ordered DNA crystals. An X-ray crystallographic study of molecule–DNA
cocrystals reveals the structural details on how the molecule interacts
with the DNA duplex. In this approach, the DNA will serve two functions:
(1) being part of the molecule to be studied and (2) forming the crystal
lattice. It is conceivable that this method will be a general method
for studying drug/peptide–DNA interactions. The resulting DNA
crystals may also find use as separation matrices, as hosts for catalysts,
and as media for material storage.
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