Large-Scale Synthesis of MOF-Derived Superporous Carbon Aerogels with Extraordinary Adsorption Capacity for Organic Solvents

Carbon aerogels (CAs) with 3D interconnected networks hold promise for application in areas such as pollutant treatment, energy storage, and electrocatalysis. In spite of this, it remains challenging to synthesize high-performance CAs on a large scale in a simple and sustainable manner. We report an eco-friendly method for the scalable synthesis of ultralight and superporous CAs by using cheap and widely available agarose (AG) biomass as the carbon precursor. Zeolitic imidazolate framework-8 (ZIF-8) with high porosity is introduced into the AG aerogels to increase the specific surface area and enable heteroatom doping. After pyrolysis under inert atmosphere, the ZIF-8/AG-derived nitrogen-doped CAs show a highly interconnected porous mazelike structure with a low density of 24 mg cm⁻³, a high specific surface area of 516 m² g⁻¹, and a large pore volume of 0.58 cm⁻³ g⁻¹. The resulting CAs exhibit significant potential for application in the adsorption of organic pollutants.     

Homogeneous Oligomeric Ligands Prepared via Radical Polymerization that Recognize and Neutralize a Target Peptide

Abiotic ligands that bind to specific biomolecules have attracted attention as substitutes for biomolecular ligands, such as antibodies and aptamers. Radical polymerization enables the production of robust polymeric ligands from inexpensive functional monomers. However, little has been reported about the production of monodispersed polymeric ligands. Herein, we present homogeneous ligands prepared via radical polymerization that recognize epitope sequences on a target peptide and neutralize the toxicity of the peptide. Taking advantage of controlled radical polymerization and separation, a library of multifunctional oligomers with discrete numbers of functional groups was prepared. Affinity screening revealed that the sequence specificity of the oligomer ligands strongly depended on the number of functional groups. The process reported here will become a general step for the development of abiotic ligands that recognize specific peptide sequences.     

Regulated Single‐Axis Rotations of a Carbonaceous Guest in a van der Waals Complex with an Entropy Cost

In a tight host–guest complex assembled solely by nondirectional van der Waals forces, unique motions of the guest, such as solid‐state inertial rotations, emerge. The regulation of dynamic motions is an important element to be explored for novel functions of such complexes, which may be seemingly difficult to achieve because of the nondirectionality of the assembling forces. A regulated, single‐axis rotation was made possible by choosing an appropriate shape of the guest in the tubular host. Specifically, an ellipsoidal guest was made to stand along a cylinder axis of the host, which consequently resulted in single‐axis rotations of the guest in the solid. The rotational frequency was considerably high for solid‐state rotations but was suppressed to 10 GHz, which was 1/20 of the isotropic rotation of a spherical guest. In‐depth kinetic analyses quantitatively revealed that the entropy cost was a determining factor that regulated the dynamics.     

Facile synthesis of an ambient stable pyreno[4,5-b]pyrrole monoanion and pyreno[4,5-b:9,10-b′]dipyrrole dianion: from serendipity to design

The stability of singly or multiply negatively charged π-conjugated organic compounds is greatly influenced by their electronic delocalization. Herein, we report a strategic methodology for isolation of a mysterious compound. The isolated compounds, a pyreno[4,5-b]pyrrole monoanion and pyreno[4,5-b:9,10-b′]dipyrrole dianion, were highly stable under ambient conditions due to high delocalization of the negative charge over multiple electron deficient C N groups and pyrene π-scaffolds and allowed purification by column chromatography. To our knowledge, this is the first report on TCNE type reductive condensation of malononitrile involving pyrene di- and tetraone and formation of pyrenopyrrole. All compounds were characterized by spectroscopic methods and X-ray crystallography. A UV-vis spectroscopic study shows an intense low energy absorption band with a large absorption coefficient (ε).

An ambient stable pyreno[4,5-b]pyrrole monoanion and pyreno[4,5-b:9,10-b′]dipyrrole dianion have been isolated and characterized, showing a low energy intense absorption band with the absorption coefficient reaching 7.1 × 10⁴ dm³ mol⁻¹ cm⁻¹.     

Competitive Assay for Theophylline Based on an Abasic Site‐Containing DNA Duplex Aptamer and a Fluorescent Ligand

A fluorescence assay for theophylline, one of the common drugs for acute and chronic asthmatic conditions, has been developed based on an abasic site‐containing DNA duplex aptamer (AP aptamer) in combination with an abasic site‐binding fluorescent ligand, riboflavin. The assay is based on the competitive binding of theophylline and riboflavin at the abasic (AP) site of the AP aptamer. In the absence of theophylline, riboflavin binds to the receptor nucleotide opposite the AP site, which leads to fluorescence quenching of the riboflavin. Upon addition of theophylline, competitive binding occurs between theophylline and riboflavin, which results in an effective fluorescence restoration due to release of riboflavin from the AP site. From an examination of the optimization of the AP aptamers, the complex of riboflavin with a 23‐mer AP aptamer (5′‐TCT GCG TCC AGX GCA ACG CAC AC‐3′/5′‐GTG TGC GTT GCC CTG GAC GCA GA‐3′; X : the AP site (Spacer C3, a propylene residue)) possessing cytosine as a receptor nucleotide was found to show a selective and effective fluorescence response to theophylline; the limit of detection for theophylline was 1.1 μM . Furthermore, fluorescence detection of theophylline was successfully demonstrated with high selectivity in serum samples by using the optimized AP aptamer and riboflavin.     

Stabilization of High‐Valence Ruthenium with Silicotungstate Ligands: Preparation,Structural Characterization,and Redox Studies of Ruthenium(III)‐Substituted α‐Keggin‐Type Silicotungstates with Pyridine Ligands, [SiW11O39RuIII(Py)]5−

Ruthenium(III)‐substituted α‐Keggin‐type silicotungstates with pyridine‐based ligands, [SiW₁₁O₃₉Ru^III(Py)]^5?, (Py: pyridine ( 1 ), 4‐pyridine‐carboxylic acid ( 2 ), 4,4′‐bipyridine ( 3 ), 4‐pyridine‐acetamide ( 4 ), and 4‐pyridine‐methanol ( 5 )) were prepared by reacting [SiW₁₁O₃₉Ru^III(H₂O)]^5? with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and ¹H NMR spectroscopy, elemental analysis, titration, and X‐ray absorption near‐edge structure (XANES) analysis (Ru K‐edge and L₃‐edge). Single‐crystal X‐ray analysis of compounds 2 , 3 , and 4 revealed that Ru^III was incorporated in the α‐Keggin framework and was coordinated by pyridine derivatives through a Ru? N bond. In the solid state, compounds 2 and 3 formed a dimer through π? π interaction of the pyridine moieties, whereas they existed as monomers in solution. CV indicated that the incorporated Ru^III–Py was reversibly oxidized into the Ru^IV–Py derivative and reduced into the Ru^II–Py derivative.     

Complete description of invariant Einstein metrics on the generalized flag manifold SO(2n)/U(p)?× U(n ? p)

We find the precise number of non-K?hler SO(2n)-invariant Einstein metrics on the generalized flag manifold M = SO(2n)/U(p)×U(n−p) with n ≥ 4 and 2 ≤ p ≤ n−2. We use an analysis on parametric systems of polynomial equations and we give some insight towards the study of such systems. We also examine the isometric problem for these Einstein metrics.     

Magnetic structures of exchange bias Ni/FeF2(1 1 0) interface

Electronic and magnetic structures of ferromagnetic (FM)/antiferromagnetic (AFM), Ni/FeF₂(1 1 0), with a compensated AFM interface are investigated by using the full-potential linearized augmented plane-wave method. We find that magnetic structures at the AFM interface are perturbed by a contact with the FM material, where the superexchange interaction through the interface F excites and induces a small net moment at the AFM interface. These results predicted may play an important role for explaining the exchange bias in this system, and rule out the exchange bias mechanisms with the spin-flop coupling and the magnetic moment reorientation.     

Development of Sulfonic-Acid-Functionalized Mesoporous Materials: Synthesis and Catalytic Applications

Sulfonic acid based mesostructures (SAMs) have been developed in recent years and have important catalytic applications. The primary applications of these materials are in various organic synthesis reactions, such as multicomponent reactions, carbon–carbon bond couplings, protection reactions, and Fries and Beckman rearrangements. This review aims to provide an overview of the recent developments in the field of SAMs with a particular emphasis on the reaction scope and advantages of heterogeneous solid acid catalysts.