Interpenetration of low‐dimensional networked structural motifs crucially affects porosity, stability, and properties of the whole reticular framework. However, varying and controlling the manner of ...interpenetration is still challenging. Herein, a porous hydrogen‐bonded organic framework (HOF) with wvm‐like weave constructed by triaxially woven chicken wires of X‐shaped tetra‐armed tetrakis(carboxybiphenyl)ethene CBPE, formally 4′,4′′′,4′′′′′,4′′′′′′′‐(ethene‐1,1,2,2‐tetrayl)tetrakis(1,1′‐biphenyl‐4‐carboxylic acid), is reported. The structure is a contrast to a non‐interpenetrated layered framework composed of tetrakis(4‐carboxyphenyl)ethene CPE. This exotic framework of CBPE is due to the disproportionate conformation of the outer four phenylene rings in the peripheral biphenyl arms. The activated framework CBPE‐1a exhibits thermal stability up to 220 °C and a BET surface area of 555 m2 g−1. Additionally, the HOF shows mechanochromic behavior in terms of fluorescence color and quantum efficiency. The achievement of the present HOFs can provide insight into constructing a new type of functional porous organic materials with interwoven network structures.
Knitting molecules into an interwoven grid: Tetrakis(carboxybiphenyl)ethene CBPE provides a porous hydrogen‐bonded organic framework (HOF) with wvm‐like weave through three‐directional interpenetration of chicken wires. The HOF exhibits thermal stability up to 220 °C, a surface area of 555 m2 g−1, and mechanochromic fluorescence property.
Colonization of new ecological niches has triggered large adaptive radiations. Although some lineages have made use of such opportunities, not all do so. The factors causing this variation among ...lineages are largely unknown. Here, we show that deficiency in docosahexaenoic acid (DHA), an essential ω-3 fatty acid, can constrain freshwater colonization by marine fishes. Our genomic analyses revealed multiple independent duplications of the fatty acid desaturase gene
in stickleback lineages that subsequently colonized and radiated in freshwater habitats, but not in close relatives that failed to colonize. Transgenic manipulation of
in marine stickleback increased their ability to synthesize DHA and survive on DHA-deficient diets. Multiple freshwater ray-finned fishes also show a convergent increase in
copies, indicating its key role in freshwater colonization.
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•Nanostructured polymer films were formed by ADMET polymerization of LC mixtures.•Anionic nanochannels in the membrane were prepared by photocleavage reaction.•The membranes showed ...selective adsorption depending on charges and molecular sizes.
Self-standing polymer membranes with nanopores were prepared by polymerization of a liquid-crystalline (LC) columnar mixture of a taper-shaped molecule having a photocleavable moiety and a lithium salt. The photocleavable moiety, o-nitrobenzyl ester links the dendritic polymerizable hydrophobic part containing vinyl groups and a hydrophilic tri(oxyethylene) chain. The mixture of the taper-shaped molecule and lithium triflate forms a columnar LC phase at a temperature range wider than 50 °C. Self-standing polymer membranes with nanostructures were prepared by acyclic diene metathesis (ADMET) polymerization of the LC mixtures. Ordered anionic nanochannels were formed in the polymer membranes by photocleavage reaction of the linkers between the polymerized hydrophobic part and the non-polymerizable hydrophilic part. The nanoporous membranes showed selective adsorption of cationic organic dyes from their aqueous solutions depending on charges and sizes of the molecules.
The library of isostructural porous frameworks enables a systematic survey to optimize the structure and functionality of porous materials. In contrary to metal-organic frameworks (MOFs) and covalent ...organic frameworks (COFs), a handful of isostructural frameworks have been reported for hydrogen-bonded organic frameworks (HOFs) due to the weakness of the bonds. Herein, we provide a rule-of-thumb to develop isostructural HOFs, where we demonstrate the construction of the third and fourth generation of isostructural HAT-based HOFs (
TolHAT-1
and
ThiaHAT-1
) by considering three important structural factors, that are (1) directional H-bonding, (2) shape-fitted docking of the HAT core, and (3) modulation of peripheral moieties. Their structural and photo-physical properties including HCl vapor detection are presented. Moreover,
TolHAT-1
,
ThiaHAT-1
, and other isostructural HOFs (
CPHAT-1
and
CBPHAT-1
) were thoroughly compared from the viewpoints of structures and properties. Importantly, molecular dynamics (MD) simulation proves to be rationally capable of evaluating the stability of isostructural HOFs. These results can accelerate the development of various isostructural molecular porous materials.
The library of isostructural porous frameworks enables a systematic survey to optimize the structure and functionality of porous materials.
Hydrogen-bonded organic frameworks (HOFs) have attracted renewed attention as another type of promising candidates for functional porous materials. In most cases of HOF preparation, the applied ...molecular design principle is based on molecules with rigid π-conjugated skeleton together with more than three H-bonding groups to achieve 2D- or 3D-networked structures. However, the design principle does not always work, but results in formation of unexpected structures, where subtle structural factors of which we are not aware dictate the entire structure of HOFs. In this contribution, we assess recent advances in HOFs, focusing on those composed of hexatopic building block molecules, which can provide robust frameworks with a wide range of topologies and properties. The HOFs described in this work are classified into three types, depending on their H-bonded structural motifs. Here in, we focus on: (1) the chemical aspects that govern their unique fundamental chemistry and structures; and (2) their photophysics at the ensemble and single-crystal levels. The work addresses and discusses how these aspects affect and orient their photonic applicability. We trust that this contribution will provide a deep awareness and will help scientists to build up a systematic series of porous materials with the aim to control both their structural and photodynamical assets.
The purpose of this study was to investigate whether and how vagus nerve stimulation (VNS) reduces the epileptogenic activity in the bilateral cerebral cortex in patients with intractable epilepsy. ...We analyzed the electrocorticograms (ECoGs) of five patients who underwent callosotomy due to intractable epilepsy even after VNS implantation. We recorded ECoGs and analyzed power spectrum in both VNS OFF and ON phases. We counted the number of spikes and electrodes with epileptic spikes, distinguishing unilaterally and bilaterally hemispherically spread spikes as synchronousness of the epileptic spikes in both VNS OFF and ON phases. There were 24.80 ± 35.55 and 7.20 ± 9.93 unilaterally spread spikes in the VNS OFF and ON phases, respectively (P = 0.157), and 35.8 ± 29.21 and 10.6 ± 13.50 bilaterally spread spikes in the VNS OFF and ON phases, respectively (P = 0.027). The number of electrodes with unilaterally and bilaterally spread spikes in the VNS OFF and ON phases was 3.84 ± 2.13 and 3.59 ± 1.82 (P = 0.415), and 8.20 ± 3.56 and 6.89 ± 2.89 (P = 0.026), respectively. The ECoG background power spectra recordings in the VNS OFF and ON phases were also analyzed. The spectral power tended to be greater in the high-frequency band at VNS ON phase than OFF phase. This study showed the reduction of epileptogenic spikes and spread areas of the spikes by VNS as immediate effects, electrophysiologically.
Cyanide induces acute lethal poisoning resulting from inhibition of cytochrome c oxidase located in the complex IV (Complex IV) of mitochondria. However, current therapies for cyanide poisoning using ...hydroxocobalamin and nitrous acid compounds remain a clinical issue. Here, we show that liposome-encapsulated methemoglobin (metHb@Lipo), nanosized biomimetic red blood cells, replicate the antidotal mechanism of nitrous acid compounds against cyanide poisoning, achieving superior efficacy and fast action with no adverse effects. The structure of metHb@Lipo, which consists of concentrated methemoglobin in its aqueous core and a lipid membrane resembling the red blood cell membrane, provides favorable characteristics as a cyanide antidote, such as binding properties and membrane permeability. Upon cyanide exposure, metHb@Lipo maintained the mitochondrial function in PC12 cells, resulting in a cell viability comparable to treatment with nitrous acid compounds. In a mouse model of cyanide poisoning, metHb@Lipo treatment dramatically improved mortality with a rapid recovery from the symptoms of cyanide poisoning compared to treatment with nitrous acid compounds. Furthermore, metHb@Lipo also possesses satisfactory pharmacokinetic properties without long-term bioaccumulation and toxicity. Our findings showed a novel concept to develop drugs for cyanide poisoning and provide a promising possibility for biomimetic red blood cell preparations for pharmaceutical applications.
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•metHb@Lipo is encapsulated methemoglobin in liposome, which mimics red blood cell.•metHb@Lipo replicates the antidotal mechanism of nitrite against cyanide poisoning.•metHb@Lipo possesses superior antidotal effect than nitrite and hydroxocobalamin.•metHb@Lipo has favorable pharmacokinetic properties and biocompatibility.
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