Featured
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News & Views |
Restoring order
A balance between order and disorder provides living materials with just the right amount of disorder needed to sustain life. This feature is currently not found in synthetic materials. Now, a route to the production of composite membranes that are simultaneously stiff and reconfigurable upon contact has been developed.
- Ankit Jain
- & Rein V. Ulijn
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Article |
Odd–even alternations in helical propensity of a homologous series of hydrocarbons
Even- and odd-numbered homologues of some hydrocarbons are known to exhibit different trends in solid-state properties. Now, experimental and computational investigations on a homologous series of a stereochemically well-defined hydrocarbon have revealed an odd–even effect in conformational behaviour in solution that is caused by a single gauche interaction.
- Johan A. Pradeilles
- , Siying Zhong
- & Varinder K. Aggarwal
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Article |
Coordination cages as permanently porous ionic liquids
Porous liquids promise to combine the advantages of the porosity of solids with those of the fluidity of liquids. Now, a permanently porous ionic-liquid coordination cage has been assembled that encapsulates isomers of butanol and propanol with some size and shape selectivity, as well as three gaseous chlorofluorocarbons with a size-dependent affinity.
- Lillian Ma
- , Cally J. E. Haynes
- & Jonathan R. Nitschke
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Perspective |
Proteomimetics as protein-inspired scaffolds with defined tertiary folding patterns
The complexity of proteins has inspired chemists to seek artificial mimetics of protein structure and function. Historically, most such work has focused on analogues of small, isolated segments; however, there is growing interest in mimicry of larger, intact tertiary folds. This Perspective surveys the emerging body of work on these agents, termed ‘proteomimetics’, discusses their construction and outlines some of the remaining challenges.
- W. Seth Horne
- & Tom N. Grossmann
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Article |
Global aromaticity at the nanoscale
Does aromaticity have a size limit? Evidence is presented for global aromaticity in porphyrin nanorings with circuits of up to 162 π-electrons. The conformation of the nanoring can be altered by changing the template, which in turn controls the aromaticity. Whenever a ring current is observed, its direction is correctly predicted by Hückel’s rule.
- Michel Rickhaus
- , Michael Jirasek
- & Harry L. Anderson
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Article |
Simultaneous CO2 capture and metal purification from waste streams using triple-level dynamic combinatorial chemistry
Carbon capture technologies are poised to play an important role in reducing CO2 emissions to mitigate global warming, but their cost prevents their extensive use. Now, CO2 capture and utilization have been combined using a triple-level dynamic combinatorial approach. CO2 was spontaneously captured by industrial polyamines to create libraries of ligands that can be used for the separation and recovery of metals.
- Jean Septavaux
- , Clara Tosi
- & Julien Leclaire
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Thesis |
Hofmeister’s curse
Understanding the effects of adding a simple salt to an aqueous solution of a protein is far from simple — and Bruce C. Gibb explains why.
- Bruce C. Gibb
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Article |
The role of sugar-backbone heterogeneity and chimeras in the simultaneous emergence of RNA and DNA
The emergence of pristine RNA and DNA on the early Earth would have been hindered by a lack of specificity in their prebiotic syntheses. Now, it has been shown that chimeric sequences—with a mixture of RNA and DNA backbones—mediate the template-directed ligation of oligomers present in mixtures of nucleic acids, enabling the simultaneous appearance of RNA and DNA.
- Subhendu Bhowmik
- & Ramanarayanan Krishnamurthy
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News & Views |
Chirality makes a move
Interlocked molecules can exhibit chiral stereogenic elements that are not found in covalently bound systems. Now, the shuttling of the ring in a [2]rotaxane has been shown to result in enantiomeric co-conformations that selectively bind chiral guests.
- Ellen M. G. Jamieson
- & Stephen M. Goldup
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News & Views |
Biomaterials in non-integer dimensions
Nature harnesses fractal geometry to create structures with unusual surface-to-volume ratios. Now, a new design approach enables the reversible assembly of functional enzymes into arboreal patterns with fractal geometry.
- Iris D. Young
- & James S. Fraser
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Article |
Stimulus-responsive self-assembly of protein-based fractals by computational design
Fractal topologies are ubiquitous, and synthetic fractal objects provide unique functional advantages by virtue of their high surface area:volume ratios. Now, a computationally guided bottom-up design approach for constructing protein-based fractal assemblies in response to phosphorylation has been developed. Designed assemblies are shown to perform reversible and efficient molecular capture.
- Nancy E. Hernández
- , William A. Hansen
- & Sagar D. Khare
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News & Views |
Clocking growth and collapse
In biological systems, order typically emerges from out-of-equilibrium molecular processes that control both static patterns and dynamic changes. Now, the self-regulating assembly and disassembly of a synthetic system has been achieved on the micrometre scale, by coupling the growth of a DNA nanotube to a biochemical oscillator.
- Tim Liedl
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Article |
Autonomous dynamic control of DNA nanostructure self-assembly
Nucleic acid nanotechnology offers a promising route towards the design and synthesis of reconfigurable biomolecular materials. Now, the combination of dynamic and structural DNA nanotechnology has enabled the dynamic control of the assembly and disassembly of DNA nanotubes. The process involves minimal synthetic gene systems, including an autonomous molecular oscillator.
- Leopold N. Green
- , Hari K. K. Subramanian
- & Elisa Franco
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Article |
Shear-induced assembly of a transient yet highly stretchable hydrogel based on pseudopolyrotaxanes
Synthetic dissipative systems, formed by out-of-equilibrium self-assembly processes, can mimic some of the properties of biological systems, but often show poor mechanical performance. Now, a shear-induced transient hydrogel has been prepared that is also highly stretchable. The system is based on coordination interactions between Cu(ii) centres and the pendant carboxylate groups of a pseudopolyrotaxane.
- Hua Ke
- , Liu-Pan Yang
- & Wei Jiang
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News & Views |
The molecular Lego movie
The structure of self-assembled aggregates depends critically on the manner in which the building blocks organize themselves. Now, such a self-assembly process has been monitored in situ using liquid-phase transmission electron microscopy, unveiling a new pathway of vesicle formation.
- Arash Nikoubashman
- & Friederike Schmid
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Article |
Braiding, branching and chiral amplification of nanofibres in supramolecular gels
Helical structures play important roles in biological processes, yet their aggregation into fibres—which can in turn form gels—is poorly understood. Now, the self-assembly of a linear pentakis (urea) peptidomimetic compound into helices that further intertwine into well-defined braided structures has been described and analysed through braid theory. Homochiral gels may be formed by exposing the precursor sol to a chiral material.
- Christopher D. Jones
- , Henry T. D. Simmons
- & Jonathan W. Steed
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Article |
Liquid–liquid phase separation during amphiphilic self-assembly
Amphiphilic self-assembly is ubiquitous both in nature and synthetic systems, yet the underlying mechanisms governing the transition from molecules to assemblies have not yet been fully resolved. Now, the role of liquid–liquid phase separation prior to the assembly process has been explored through the detailed analysis of a model block-copolymer system.
- Alessandro Ianiro
- , Hanglong Wu
- & Joseph P. Patterson
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Article |
Catalytic transport of molecular cargo using diffusive binding along a polymer track
One-dimensional diffusive binding represents an important mechanism used by nature to facilitate many fundamental biochemical processes. Now, a completely synthetic system with similar capabilities has been constructed. The system was exploited to significantly speed up bimolecular reactions and to catalytically transport molecular cargo in solution and within physically separated compartments.
- Lifei Zheng
- , Hui Zhao
- & Wilhelm T. S. Huck
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Article |
Heteromultivalent peptide recognition by co-assembly of cyclodextrin and calixarene amphiphiles enables inhibition of amyloid fibrillation
Heteromultivalency, which involves the simultaneous interactions of more than one type of ligand with more than one type of receptor, is common in biological systems but challenging to engineer artificially. Now, a heteromultivalent platform prepared by co-assembling cyclodextrin and calixarene amphiphiles has shown self-adaptive peptide binding with high affinity. The platform was used to sequester amyloid β-peptides, reducing amyloid cytotoxicity.
- Zhe Xu
- , Shaorui Jia
- & Dong-Sheng Guo
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Article |
A biomimetic receptor for glucose
Synthetic receptors can be used to help understand biological systems, but rarely compete in terms of affinity or selectivity. Now, a glucose-binding compound has been prepared that, despite its symmetry and simplicity, can match all but the strongest glucose-binding proteins. The high binding affinity and outstanding selectivity of this receptor may translate into biomedical applications.
- Robert A. Tromans
- , Tom S. Carter
- & Anthony P. Davis
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Article |
Cavitation energies can outperform dispersion interactions
Binding interactions, whether between a biological receptor and ligand or between a synthetic host and guest, are frequently stronger for larger molecules than for smaller ones. This is commonly believed to arise from increased dispersion interactions, but it has now been shown that cavitation energies—always required to dissolve molecules in solution—can be more important.
- Suhang He
- , Frank Biedermann
- & Werner M. Nau
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News & Views |
What tangled webs we weave
Knots have been rigorously studied since the 1860s, but only in the past 30 years have they been made in the laboratory in molecular form. Now, the most complex small-molecule examples so far — a composite knot and an isomeric link, each with nine crossings — have been prepared.
- Edward E. Fenlon
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Article |
Stereoselective synthesis of a composite knot with nine crossings
A composite knot with nine crossings of the same handedness has been prepared from a hexameric circular helicate in 41% yield in a two-step synthesis. An isomeric cyclic [3]catenane topologically constrained to always have at least three twists within the links is also formed. Both topologies have a high degree of writhe, analogous to that of supercoiled DNA.
- Liang Zhang
- , Alexander J. Stephens
- & David A. Leigh
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Article |
Highly reduced and protonated aqueous solutions of [P2W18O62]6− for on-demand hydrogen generation and energy storage
The polyoxoanion [P2W18O62]6− has been shown to reversibly accept up to 18 electrons upon reduction in aqueous solution. The resulting highly reduced solution can then be used either for the on-demand generation of hydrogen over a catalyst bed, or as a high-energy-density electrolyte in a redox flow battery.
- Jia-Jia Chen
- , Mark D. Symes
- & Leroy Cronin
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Article |
Light-driven molecular trap enables bidirectional manipulation of dynamic covalent systems
Light can selectively drive and control the reversible reaction between a nitrogen nucleophile and a photoswitchable carbonyl electrophile by inducing wavelength-specific tautomerization cycles. This enables external and bidirectional regulation of closed dynamic covalent systems via C=N exchange, resembling a light-powered bidirectional molecular-scale Dean–Stark trap.
- Michael Kathan
- , Fabian Eisenreich
- & Stefan Hecht
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Article |
Ring-through-ring molecular shuttling in a saturated [3]rotaxane
Controlled motion in mechanically interlocked molecules, such as a macrocycle moving back and forth along the axle of a rotaxane, forms the basis of complex functions in molecular machinery. Now, ring-through-ring shuttling has been achieved using two macrocycles that switch position between two anchoring sites, which involves the smaller ring passing through the larger one.
- Kelong Zhu
- , Giorgio Baggi
- & Stephen J. Loeb
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Article |
Amino-acid-encoded biocatalytic self-assembly enables the formation of transient conducting nanostructures
Amino acids have now been used as chemical inputs to provide control over self-assembly in semiconducting structures. This approach enables temporal control over the formation of nanostructures and consequently control over their transient electronic conductivity.
- Mohit Kumar
- , Nicole L. Ing
- & Rein V. Ulijn
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Article |
Dynamic actuation of glassy polymersomes through isomerization of a single azobenzene unit at the block copolymer interface
Biological systems are made up of complex networks that can respond to stimuli and function across relatively long distances in molecular terms. Now, it has been shown that a local disruption (the isomerization of just a single azobenzene unit) at the interface of supramolecular glassy polymersomes can immediately spread through over 500 bonds, significantly changing membrane permeability and enabling controllable release of guest molecules.
- Mijanur Rahaman Molla
- , Poornima Rangadurai
- & S. Thayumanavan
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Article |
Experimental and computational evidence of halogen bonds involving astatine
Halogen bonding is known to get stronger with increasing halogen polarizability, but some trends of the periodic table break down for heavy elements owing to relativistic effects. Now, through distribution coefficient measurements and relativistic quantum mechanical calculations, AtI has been shown to form stronger halogen bonds than I2—meaning that astatine conforms to the trend.
- Ning Guo
- , Rémi Maurice
- & Nicolas Galland
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Article |
Complex supramolecular interfacial tessellation through convergent multi-step reaction of a dissymmetric simple organic precursor
Complex interfacial supramolecular architectures promise unique physical and chemical properties, but are challenging to make. Now, it has been shown that a simple organic precursor can undergo a convergent multi-step on-surface transformation to give more complex building blocks that assemble into a semi-regular Archimedean tessellation with long-range order.
- Yi-Qi Zhang
- , Mateusz Paszkiewicz
- & Florian Klappenberger
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News & Views |
Stressed out crystals
Molecular crystals have recently started to shake their inflexible reputation. Now, copper(II) acetylacetonate needles have been shown to be very flexible, and their mechanical deformation has been assessed through materials constants using methods customarily reserved for non-molecular materials.
- Bart Kahr
- & Michael D. Ward
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Review Article |
Collaborative routes to clarifying the murky waters of aqueous supramolecular chemistry
Given its ubiquity, the importance of understanding the properties of water cannot be understated. Now, stemming from discussions at a National Science Foundation-supported workshop, this Review Article highlights where there is latent chemical space for potential collaborations between the physical and supramolecular communities, both of which are interested in how molecules interact with each other in water.
- Paul S. Cremer
- , Amar H. Flood
- & David L. Mobley
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Article |
DNA-imprinted polymer nanoparticles with monodispersity and prescribed DNA-strand patterns
DNA–polymer conjugates are attractive materials that combine the programmability of nucleic acid assembly with polymer functionality. Now, through a DNA cube template, monodisperse polymer particles have been imprinted with several DNA strands in pre-designed orientations— each independently set and addressable. The resulting hybrid particles can further assemble into well-defined, non-centrosymmetric structures.
- Tuan Trinh
- , Chenyi Liao
- & Hanadi F. Sleiman
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Article |
Artificial muscle-like function from hierarchical supramolecular assembly of photoresponsive molecular motors
A centimetre-long string formed by the hierarchical self-assembly of a photoresponsive amphiphilic molecular motor — composed of 95 wt% of water — undergoes muscle-like contraction. Under irradiation, rotary motion at the molecular level is amplified through non-covalent interactions to sustain a fast macroscopic mechanical motion of large amplitude.
- Jiawen Chen
- , Franco King-Chi Leung
- & Ben L. Feringa
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News & Views |
Intercalation without altercation
Building materials with clusters instead of atoms promises unconventional properties, but those 'superatomic solids' are often too fragile to manipulate. Now, intercalating a guest within an ionic layered solid made of fullerenes and metal chalcogenide clusters greatly alters its conductivity and optical properties without disrupting its crystalline structure.
- Shiv N. Khanna
- & Arthur C. Reber
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News & Views |
Supramolecular basketry
Both the topology and the mechanical strength of woven materials have inspired great synthetic efforts to replicate their structures at the nanoscale. Now, a triaxial weave has been prepared by self-assembly of a judiciously designed organic molecule through π–π and CH–π interactions.
- Yi Liu
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Article |
Self-assembly of polyhedral metal–organic framework particles into three-dimensional ordered superstructures
Colloidal particles of metal–organic frameworks (ZIF-8 and UiO-66) with different polyhedral shapes can self-assemble into well-ordered, porous three-dimensional superstructures. These superstructures function as photonic crystals, with a photonic band gap that depends on the size of the MOF particles and shifts upon the sorption of guests within their pores.
- Civan Avci
- , Inhar Imaz
- & Daniel Maspoch
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News & Views |
Gliding and trudging
Water is increasingly recognized as being of paramount importance in biological processes, yet its exact role remains difficult to elucidate. Now, the motion of water molecules within and around a synthetic peptide-amphiphile nanofibre has been precisely determined, showing significant differences between its core and surface.
- Yoshimitsu Itoh
- & Takuzo Aida
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Article |
Designing cooperatively folded abiotic uni- and multimolecular helix bundles
Rationally designed arrays of hydrogen bonds between aromatic oligoamide segments have now been shown to generate abiotic helix-turn-helix and unexpected dimeric and trimeric helix bundle motifs. These structures show kinetic and thermodynamic stability, and cooperative folding in nonpolar solvents.
- Soumen De
- , Bo Chi
- & Ivan Huc
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Article |
Atomic resolution of structural changes in elastic crystals of copper(II) acetylacetonate
Crystals are typically thought to be brittle and fragile materials, but needles of copper(II) acetylacetonate have now been shown to be flexible enough to be reversibly tied into a knot. Mechanistic investigations using synchrotron X-ray diffraction determined that the elastic bending occurs through rotation of the molecules within the crystal lattice.
- Anna Worthy
- , Arnaud Grosjean
- & John C. McMurtrie
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Article |
Signal transduction in a covalent post-assembly modification cascade
Two coordination cages have been devised that undergo covalent modification during a cascade of two orthogonal Diels–Alder reactions. This results in increased lipophilicity for the second cage, enabling its phase transfer and separation from the first. The trigger, relay and inhibition features of this cascade system mimic key aspects of natural post-translational modification cascades.
- Ben S. Pilgrim
- , Derrick A. Roberts
- & Jonathan R. Nitschke
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Article |
Dynamic covalent chemistry enables formation of antimicrobial peptide quaternary assemblies in a completely abiotic manner
Despite advances in peptide synthesis techniques, explicit control over the quaternary structure of synthetic peptides has remained elusive. Now, the dynamic covalent chemistry of hydrazide- and aldehyde-containing peptides has now been shown to enable the formation of unique quaternary structures with topological diversity. Using this method, oligomers were assembled into complex structures showing dramatic enhancements of antimicrobial effectiveness versus Staphylococcus Aureus.
- James F. Reuther
- , Justine L. Dees
- & Eric V. Anslyn
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Article |
Single-crystal-to-single-crystal intercalation of a low-bandgap superatomic crystal
Intercalation — a cornerstone of materials science with wide-ranging applications — has now been demonstrated in a superatomic crystal. A redox-active tetracyanoethylene guest was inserted into the lattice of a material consisting of alternate layers of {Co6Te8} clusters and C60 fullerenes, leading to a single-crystal-to-single-crystal transformation that significantly modulates the material's optical and electrical transport properties.
- Evan S. O'Brien
- , M. Tuan Trinh
- & Xavier Roy
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Article |
A triaxial supramolecular weave
Woven topologies endow macroscopic objects with mechanical stability, but their molecular counterparts have remained difficult to prepare. Now, an extended triaxial supramolecular weave has been formed by the self-assembly of a judiciously shaped organic building block — a rigid oligoproline segment featuring two perylene-monoimide moieties — through π–π stacking and CH–π interactions.
- Urszula Lewandowska
- , Wojciech Zajaczkowski
- & Helma Wennemers
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Article |
Thermally bisignate supramolecular polymerization
An attractive feature of supramolecular polymers is their reversibility — they typically depolymerize upon heating. Now, in the presence of a scavenger molecule, a metalloporphyrin derivative bearing eight amide-containing side chains has been shown to undergo supramolecular polymerization on heating as well as cooling through π-stacking and multivalent hydrogen-bonding interactions.
- Kotagiri Venkata Rao
- , Daigo Miyajima
- & Takuzo Aida
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News & Views |
Bringing lipid bilayers into shape
Lipid bilayers form the thin and floppy membranes that define the boundary of compartments such as cells. Now, a method to control the shape and size of bilayers using DNA nanoscaffolds has been developed. Such designer materials advance synthetic biology and could find use in membrane research.
- Stefan Howorka
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Article |
Stereochemical plasticity modulates cooperative binding in a CoII12L6 cuboctahedron
An interconverting system of three distinct stereoisomers of a cuboctahedral CoII-based cage is able to regulate the binding affinities of large anionic guests. Through cooperative templation with fullerene guests, the cage converts into a desymmetrized cage that in turn exhibits positive cooperativity in binding of an icosahedral anion; this interaction is anti-cooperative in the fullerene-free parent.
- Felix J. Rizzuto
- & Jonathan R. Nitschke
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Article |
A device that operates within a self-assembled 3D DNA crystal
Although DNA nanotechnology has found many applications in developing functional structures, there has never been an independent device contained within a 3D crystal. Now, a self-assembled three-state device that can change the colour of its crystal by diffusion of DNA-ligated dyes has been reported, representing the potential to develop programmable nanomechanical devices.
- Yudong Hao
- , Martin Kristiansen
- & Nadrian C. Seeman
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Article |
Solvent-switchable continuous-breathing behaviour in a diamondoid metal–organic framework and its influence on CO2 versus CH4 selectivity
Breathing metal–organic frameworks (MOFs) are functional materials whose molecular-scale pores can reversibly open and close. In contrast to typical defined structural transitions, continuous breathing has now been observed for a diamondoid MOF. Removal of two different solvents leads to two desolvated MOF polymorphs with dramatically different porosities and gas uptake properties, including CO2/CH4 selectivities. Partial desolvation introduces pressure-gated CO2 adsorption.
- Elliot J. Carrington
- , Craig A. McAnally
- & Lee Brammer