Separation of molecules based on molecular size in zeolites with appropriate pore aperture dimensions has given rise to the definition of "molecular sieves" and has been the basis for a variety of separation applications. We show here that for a class of chabazite zeolites, what appears to be "molecular sieving" based on dimension is actually separation based on a difference in ability of a guest molecule to induce temporary and reversible cation deviation from the center of pore apertures, allowing for exclusive admission of certain molecules. This new mechanism of discrimination permits "size-inverse" separation: we illustrate the case of admission of a larger molecule (CO) in preference to a smaller molecule (N(2)). Through a combination of experimental and computational approaches, we have uncovered the underlying mechanism and show that it is similar to a "molecular trapdoor". Our materials show the highest selectivity of CO(2) over CH(4) reported to date with important application to natural gas purification.

Creating a synthetic exoskeleton from abiotic materials to protect delicate mammalian cells and impart them with new functionalities could revolutionize fields like cell-based sensing and create diverse new cellular phenotypes. Herein, we introduce the concept of 'SupraCells', which are living mammalian cells encapsulated and protected within functional modular nanoparticle-based exoskeletons. Exoskeletons are generated within seconds through immediate interparticle and cell/particle complexation that abolishes the macropinocytotic and endocytotic nanoparticle internalization pathways that occur without complexation. SupraCell formation was shown to be generalizable to wide classes of nanoparticles and various types of cells. It induces a spore-like state, wherein cells do not replicate or spread on surfaces but are endowed with extremophile properties, e.g., resistance to osmotic stress, reactive oxygen species, pH, and UV exposure, along with abiotic properties like magnetism, conductivity, and multi-fluorescence. Upon de-complexation cells return to their normal replicative states. SupraCells represent a new class of living hybrid materials with a broad range of functionalities. Enhancing or augmenting the performance of mammalian cells could result in new classes of smart responsive living materials. Mammalian cells exhibit complex functionalities like sensing, signal transduction, and protein expression, but they remain fragile and highly susceptible to intracellular and extracellular stressors. [1] So far, to impart delicate mammalian cells with greater cellular durability, such as enhanced resistance against UV, freezing, and enzymatic attack, etc., a series of coating strategies/nanotechniques have been developed to

The development of hybrid nanomaterials mimicking antifreeze proteins that can modulate/inhibit the growth of ice crystals for cell/tissue cryopreservation has attracted increasing interests. Herein, we describe the first utilization of zirconium (Zr)-based metal−organic framework (MOF) nanoparticles (NPs) with well-defined surface chemistries for the cryopreservation of red blood cells (RBCs) without the need of any (toxic) organic solvents. Distinguishing features of this cryoprotective approach include the exceptional water stability, low hemolytic activity, and the long periodic arrangement of organic linkers on the surface of MOF NPs, which provide a precise spacing of hydrogen donors to recognize and match the ice crystal planes. Five kinds of Zr-based MOF NPs, with different pore size, surface chemistry, and framework topologies, were used for the cryoprotection of RBCs. A "splat" assay confirmed that MOF NPs not only exhibited ice recrystallization inhibition activities but also acted as a "catalyst" to accelerate the melting of ice crystals. The human RBC cryopreservation tests displayed RBC recoveries of up to ∼40%, which is higher than that obtained via commonly used hydroxyethyl starch polymers. This cryopreservation approach will inspire the design and utilization of MOF-derived nanoarchitectures for the effective cryopreservation of various cell types as well as tissue samples.

Highly selective separation of small molecules, such as CO2, N2, and CH4, is difficult to achieve if all of the molecules can access the internal surface so that the selectivity depends only on differences in interaction of these molecules with the surface. Recently, we reported on a “molecular trapdoor” mechanism (Shang, J.; et al. J. Am. Chem. Soc. 2012, 134, 19246–19253), which provides a record high selectivity through a guest-induced cation deviation process where the adsorbent exclusively admits “strong” molecules (e.g., CO2 and CO) but excludes “weak” ones (e.g., N2 and CH4). In this study, we have investigated the range of zeolite compositions (varying Si/Al and cation type) for which a trapdoor effect is present and summarize this composition range with a simple “rule of thumb”. Cation density and cation type are the controlling factors in achieving the molecular trapdoor effect on chabazites. Specifically, the “rule” requires every pore aperture connecting the supercages to accommodate one door-keeping cation of an appropriate type. This “rule” will help guide the synthesis of “trapdoor” chabazite adsorbents for the deployment of carbon capture as well as help the development of molecular trapdoor adsorbents/membranes for other small-pore zeolites, such as RHO, LTA, and other porous materials.

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The rational design of photocatalysts for efficient nitrogen (N 2 ) fixation at ambient conditions is important for revolutionizing ammonia production and quite challenging because the great difficulty lies in the adsorption and activation of the inert N 2 . Inspired by a biological molecule, chlorophyll, featuring a porphyrin structure as the photosensitizer and enzyme nitrogenase featuring an iron (Fe) atom as a favorable binding site for N 2 via π-backbonding, here we developed a porphyrin-based metal−organic framework (PMOF) with Fe as the active center as an artificial photocatalyst for N 2 reduction reaction (NRR) under ambient conditions. The PMOF features aluminum (Al) as metal node imparting high stability and Fe incorporated and atomically dispersed by residing at each porphyrin ring promoting the adsorption and the activation of N 2 , termed Al-PMOF(Fe). Compared with the pristine Al-PMOF, Al-PMOF(Fe) exhibits a substantial enhancement in NH 3 yield (635 μg g −1 cat. ) and production rate (127 μg h −1 g −1 cat. ) of 82% and 50%, respectively, on par with the best-performing MOF-based NRR catalysts. Three cycles of photocatalytic NRR experimental results corroborate a stable photocatalytic activity of Al-PMOF(Fe). The combined experimental and theoretical results reveal that the Fe−N site in Al-PMOF(Fe) is the active photocatalytic center that can mitigate the difficulty of the rate-determining step in photocatalytic NRR. The possible reaction pathways of NRR on Al-PMOF(Fe) were established. Our study of porphyrin-based MOF for the photocatalytic NRR will provide insight into the rational design of catalysts for artificial photosynthesis.

She has been af ull Professor in the Chemistry Department, Jilin University,s ince 1999. She was elected as am ember of the Chinese Academy of Sciences in 2015, academician of TWAS in 2016, and member of Academiae Europaeae in 2019. Her main research interest is in the designed synthesis and application of zeolitic nanoporous materials in energy,e nvironment, and other emerging fields. Scheme 1. Schematic of CDs confined in various PMs and the applications.

The isocyanate groups (–NCO) derived from –NC– bonds in the organic ligands enables the thermally treated ZIF-8 to act as wide-spectrum photocatalyst.