Merging and Clipping Nets for the Synthesis of Three- and Two-Merged Net Metal-Organic Frameworks.

Herein, we report how merging and clipping nets in metal-organic frameworks (MOFs) can be controlled in a single-crystal-to-single-crystal fashion using three different approaches─the merged net, clip-off chemistry, and linker reinstallation─to design and synthesize three- and two-merged net MOFs. Initially, we show the formation of three isoreticular three-merged net MOFs by linking a trimeric Sc cluster, Sc(μ-Ο)(-COO), with ditopic zigzag and tritopic linkers. The resulting MOFs exhibit three-merged edge-transitive nets─ + + ─for the first time.

Mechanistic Insights into Electronic Current Flow through Quinone Devices.

Molecular switches based on functionalized graphene nanoribbons (GNRs) are of great interest in the development of nanoelectronics. In experiment, it was found that a significant difference in the conductance of an anthraquinone derivative can be achieved by altering the pH value of the environment. Building on this, in this work we investigate the underlying mechanism behind this effect and propose a general design principle for a pH based GNR-based switch.

Multifunctional, Hybrid Materials Design via Spray-Drying: Much more than Just Drying.

Spray-drying is a popular and well-known "drying tool" for engineers. This perspective highlights that, beyond this application, spray-drying is a very interesting and powerful tool for materials chemists to enable the design of multifunctional and hybrid materials. Upon spray-drying, the confined space of a liquid droplet is narrowed down, and its ingredients are forced together upon "falling dry.

Assembly of Covalent Organic Frameworks into Colloidal Photonic Crystals.

Self-assembly of colloidal particles into ordered superstructures is an important strategy to discover new materials, such as catalysts, plasmonic sensing materials, storage systems, and photonic crystals (PhCs). Here we show that porous covalent organic frameworks (COFs) can be used as colloidal building particles to fabricate porous PhCs with an underlying face-centered cubic () arrangement. We demonstrate that the Bragg reflection of these can be tuned by controlling the size of the COF particles and that species can be adsorbed within the pores of the COF particles, which in turn alters the Bragg reflection.

Isoreticular Contraction of Metal-Organic Frameworks Induced by Cleavage of Covalent Bonds.

Isoreticular chemistry, in which the organic or inorganic moieties of reticular materials can be replaced without destroying their underlying nets, is a key concept for synthesizing new porous molecular materials and for tuning or functionalization of their pores. Here, we report that the rational cleavage of covalent bonds in a metal-organic framework (MOF) can trigger their isoreticular contraction, without the need for any additional organic linkers. We began by synthesizing two novel MOFs based on the MIL-142 family, (In)BCN-20B and (Sc)BCN-20C, which include cleavable as well as noncleavable organic linkers.

Immobilization of Agaricus bisporus Polyphenol Oxidase 4 on mesoporous silica: Towards mimicking key enzymatic processes in peat soils.

Hypothesis: The use of immobilized enzyme-type biocatalysts to mimic specific processes in soil can be considered one of the most promising alternatives to overcome the difficulties behind the structural elucidation of riverine humic-derived iron-complexes. Herein, we propose that the immobilization of the functional mushroom tyrosinase, Agaricus bisporus Polyphenol Oxidase 4 (AbPPO4) on mesoporous SBA-15-type silica could contribute to the study of small aquatic humic ligands such as phenols.

Experiments: The silica support was functionalized with amino-groups in order to investigate the impact of surface charge on the tyrosinase loading efficiency as well as on the catalytic performance of adsorbed AbPPO4.

Ammonia Capture in Rhodium(II)-Based Metal-Organic Polyhedra via Synergistic Coordinative and H-Bonding Interactions.

Ammonia (NH) is among the world's most widely produced bulk chemicals, given its extensive use in diverse sectors such as agriculture; however, it poses environmental and health risks at low concentrations. Therefore, there is a need for developing new technologies and materials to capture and store ammonia safely. Herein, we report for the first time the use of metal-organic polyhedra (MOPs) as ammonia adsorbents.

Electrochemical Conversion of Alcohols into Acidic Commodities on Nickel Sulfide Nanoparticles.

The electrocatalytic oxidation of alcohols is a potentially cost-effective strategy for the synthesis of valuable chemicals at the anode while simultaneously generating hydrogen at the cathode. For this approach to become commercially viable, high-activity, low-cost, and stable catalysts need to be developed. Herein, we demonstrate an electrocatalyst based on earth-abundant nickel and sulfur elements.

Multicomponent, Functionalized HKUST-1 Analogues Assembled via Reticulation of Prefabricated Metal-Organic Polyhedral Cavities.

Metal-organic frameworks (MOFs) assembled from multiple building blocks exhibit greater chemical complexity and superior functionality in practical applications. Herein, we report a new approach based on using prefabricated cavities to design isoreticular multicomponent MOFs from a known parent MOF. We demonstrate this concept with the formation of multicomponent HKUST-1 analogues, using a prefabricated cavity that comprises a cuboctahedral Rh(II) metal-organic polyhedron functionalized with 24 carboxylic acid groups.

Do Direct Detection Experiments Constrain Axionlike Particles Coupled to Electrons?

Several laboratory experiments have published limits on axionlike particles (ALPs) with feeble couplings to electrons and masses in the kilo-electron-volt to mega-electron-volt range, under the assumption that such ALPs comprise the dark matter. We note that ALPs decay radiatively into photons, and show that for a large subset of the parameter space ostensibly probed by these experiments, the lifetime of the ALPs is shorter than the age of the Universe. Such ALPs cannot consistently make up the dark matter, which significantly affects the interpretation of published limits from GERDA, Edelweiss-III, SuperCDMS, and Majorana.

Elucidation of Metal Local Environments in Single-Atom Catalysts Based on Carbon Nitrides.

The ability to tailor the properties of metal centers in single-atom heterogeneous catalysts depends on the availability of advanced approaches for characterization of their structure. Except for specific host materials with well-defined metal adsorption sites, determining the local atomic environment remains a crucial challenge, often relying heavily on simulations. This article reports an advanced analysis of platinum atoms stabilized on poly(triazine imide), a nanocrystalline form of carbon nitride.

Hazard assessment of abraded thermoplastic composites reinforced with reduced graphene oxide.

Graphene-related materials (GRMs) are subject to intensive investigations and considerable progress has been made in recent years in terms of safety assessment. However, limited information is available concerning the hazard potential of GRM-containing products such as graphene-reinforced composites. In the present study, we conducted a comprehensive investigation of the potential biological effects of particles released through an abrasion process from reduced graphene oxide (rGO)-reinforced composites of polyamide 6 (PA6), a widely used engineered thermoplastic polymer, in comparison to as-produced rGO.

On the thermoelectric properties of Nb-doped SrTiO epitaxial thin films.

The exploration for thermoelectric thin films of complex oxides such as SrTiO-based oxides is driven by the need for miniaturized harvesting devices for powering the Internet of Things (IoT). However, there is still not a clear consensus in the literature for the underlying influence of film thickness on thermoelectric properties. Here, we report the fabrication of epitaxial thin films of 6% Nb-doped SrTiO on (001) (LaAlO)(SrAlTaO) (LSAT) single crystal using pulsed laser deposition (PLD) where the film thickness was varied from 2 nm to 68 nm.

Assembly of Colloidal Clusters Driven by the Polyhedral Shape of Metal-Organic Framework Particles.

Control of the assembly of colloidal particles into discrete or higher-dimensional architectures is important for the design of myriad materials, including plasmonic sensing systems and photonic crystals. Here, we report a new approach that uses the polyhedral shape of metal-organic-framework (MOF) particles to direct the assembly of colloidal clusters. This approach is based on controlling the attachment of a single spherical polystyrene particle on each face of a polyhedral particle via colloidal fusion synthesis, so that the polyhedral shape defines the final coordination number, which is equal to the number of faces, and geometry of the assembled colloidal cluster.

Structural Deterioration of Well-Faceted MOFs upon HS Exposure and Its Effect in the Adsorption Performance.

The structural deterioration of archetypical, well-faceted metal-organic frameworks (MOFs) has been evaluated upon exposure to an acidic environment (HS). Experimental results show that the structural damage highly depends on the nature of the hybrid network (e.g.

Enzyme-Powered Porous Micromotors Built from a Hierarchical Micro- and Mesoporous UiO-Type Metal-Organic Framework.

Here, we report the design, synthesis, and functional testing of enzyme-powered porous micromotors built from a metal-organic framework (MOF). We began by subjecting a presynthesized microporous UiO-type MOF to ozonolysis, to confer it with mesopores sufficiently large to adsorb and host the enzyme catalase (size: 6-10 nm). We then encapsulated catalase inside the mesopores, observing that they are hosted in those mesopores located at the subsurface of the MOF crystals.

Porous materials as carriers of gasotransmitters towards gas biology and therapeutic applications.

The discovery of NO, CO, and H2S as gasotransmitters and their beneficial role in multiple physiological functions opened an era of research devoted to exogenously delivering them as therapeutic agents. However, the gaseous nature of these molecules demands new forms of administration that enable one to control the location, dosage and timing of their delivery. Porous materials are among the most suitable scaffolds to store, deliver and release gasotransmitters due to their high surface area, tunable composition and reactivity.

Spray-Drying Synthesis of MOFs, COFs, and Related Composites.

ConspectusMetal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are among the most attractive porous materials today. They exhibit outstanding porosity for countless applications such as gas storage, CO capture, gas separation, sensing, drug delivery, and catalysis. Moreover, researchers have recently begun to combine MOFs or COFs with other functional materials to obtain composites that boast the respective strengths, and mitigate the respective weaknesses, of each component, enabling enhanced performance in many of the aforementioned applications.

Molecular causes of primary microcephaly and related diseases: a report from the UNIA Workshop.

The International University of Andalucía (UNIA) Current Trends in Biomedicine Workshop on Molecular Causes of Primary Microcephaly and Related Diseases took place in Baeza, Spain, November 18-20, 2019. This meeting brought together scientists from Europe, the USA and China to discuss recent advances in our molecular and genetic understanding of a group of rare neurodevelopmental diseases characterised by primary microcephaly, a condition in which head circumference is smaller than normal at birth. Microcephaly can be caused by inherited mutations that affect key cellular processes, or environmental exposure to radiation or other toxins.

Net-Clipping: An Approach to Deduce the Topology of Metal-Organic Frameworks Built with Zigzag Ligands.

Herein we propose a new approach for deducing the topology of metal-organic frameworks (MOFs) assembled from organic ligands of low symmetry, which we call . It is based on the construction of nets by rational deconstruction of edge-transitive nets comprising higher-connected molecular building blocks (MBBs). We have applied net-clipping to predict the topologies of MOFs containing zigzag ligands.

Splicing Calls Back.

Removal of introns from eukaryotic messenger RNA precursors often occurs co-transcriptionally. In this issue of Cell, Fiszbein et al. report that evolutionary or tissue-specific activation of an internal exon can enhance gene expression by promoting the use of alternative transcription initiation sites.