A topologically chiral catenane was synthesized and resolved by a diastereomer method. The catenane consisting of a Cs symmetrical crown ether and a Cs symmetrical ammonium macrocycle was obtained as a racemic mixture. Introduction of a chiral auxiliary to the catenane gave a diastereomeric mixture which was successfully resolved. Removal of the chiral auxiliary from both enantiomers of the catenane gave rise to mirror images of their CD spectra.
The synthesis of unstable aryl difluorovinyl pinacolboronates was achieved by the dehydrofluorination of α-trifluoromethyl arylmethyl pinacolboronates with LDA. These aryl difluorovinyl pinacolboronates can be used for Suzuki-Miyaura coupling with various aryl halides under Pd-catalysis to furnish diaryl gem-difluorovinyl compounds.
We prepared amphoteric statistical copolymers from cationic vinylbenzyltrimethylammonium chloride and anionic sodium p-styrenesulfonate via a reversible addition-fragmentation chain transfer reaction. The copolymers show upper critical solution temperature (UCST) behavior in aqueous solutions depending on charge interactions. Maintaining the stoichiometric charge ratio of cationic and anionic units in the copolymer is crucial for the UCST.
A strategy for easily constructing a sensor array that mimics a biological sensory mechanism, i.e., a so-called chemical tongue, based on a single material is reported. An array of aqueous solutions of a cationic block-copolymer modified with an environmentally responsive fluorophore can convert information from the pH-dependent polymer–protein interactions into patterns of fluorescence change. This chemical tongue allowed discriminating (i) 16 different proteins and (ii) mixtures containing various compositions of disease-marker proteins.
In this paper, activated carbon models with different pore size distribution (PSD) and oxidation degree were constructed, and the adsorption processes of benzene on models under 303.15 K were analyzed by molecular simulation technology. The adsorption mechanisms including adsorption isotherms, energy changes, PSD changes after benzene adsorption, radial distribution functions (RDFs), and diffusion coefficients were discussed in detail. This can provide guidance for micro-control of activated carbon structure and more reasonable selection in practical applications.
The protein stability of the Met16Leu pseudoazurin (PAz) variant was examined by electrospray ionization mass spectrometry (ESI-MS), and the protein stability was similar to that of WT, which has an S-π interaction in the second coordination sphere. The stability of Met16Leu PAz was remarkably higher than that of the aliphatic amino acid variants Met16Val and Met16Ile PAz. The CH-π interactions between the Cu-coordinated His81 imidazole ring and the two methyl groups of the substituted leucine residue acts to stabilize the protein.
Anionic polymerization of methacrylate-functionalized ionic monomers, 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTAC) and 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (MAPS), was performed using conventional alkyl lithium as an initiator in ionic liquid, leading to poly(MTAC) (PMTAC) and poly(MAPS) (PMAPS). During an anionic polymerization, ionic liquid acts as solvent and additive. The dual role of ionic liquid gives PMAPS heterotactic configuration.
In this study, calcium ferrite (CaFe2O4) nanorod thin films are synthesized using the molten salt method and applied to photocathodes. SEM observation showed nanorod structure was constructed on Pt substrate by this method with lower temperature than conventional processes. Moreover, photoelectrochemical results demonstrate that the synthesized CaFe2O4 nanorods exhibited higher photo response as compared to CaFe2O4 rods prepared without using this method. Thus, the method in this work provides an economical avenue for facile synthesis of CaFe2O4-based photofunctional materials.
Development of innovative polymer electrolytes that simultaneously possesses high mechanical stiffness as well as liquid-like ion motions is desirable for safer lithium-ion secondary batteries. Herein, bifunctional poly(ethylene glycol) diacrylate (PEGDA) based cross-linked network polymer electrolytes (PE) plasticized by tetraglyme at various lithium salt concentrations were fabricated via a solvent-free UV-curing process using a photo-initiator, 2,2-dimethoxy-2-phenylacetophenone (DMAP). The outstanding results demonstrate potential for safer high-performance rechargeable lithium-ion batteries.
Though dye-sensitized solar cells (DSCs) made from less photo-catalytically active tin and zinc oxides are inefficient, composite tin-zinc oxide films yield efficiencies comparable to those fabricated out of titanium dioxide films. Studies conducted reveal that DSCs based tin-zinc oxide films are highly stable when high boiling point solvents are incorporated to solubilize the conventional iodide/tri-iodide redox system.
Cell membranes are fluidic, and the fluidic properties give unique biological functions to the membranes. Here, we review the application of fluorescence lifetime correlation analyses to elucidate the leaflet-specific lipid diffusion in a model cell membrane supported on a glass surface. Utilization of fluorescence lifetime enables us to discriminate the signals from each leaflet of the lipid bilayer and to analyze the lipid diffusion in a leaflet-specific manner. The results showed that the lipid diffusion in a proximal leaflet facing a glass surface is sensitive to the strength of the electrostatic interaction between the lipid headgroup and the glass surface whereas that in the distal one is insensitive to it. This clearly indicates that the interleaflet coupling is negligible. Because the strength of the interleaflet coupling is highly relevant to the cooperative formation of functional domains across the bilayer, this work provides an important insight into the lipid dynamics in cell membranes.
The oxidative coupling of benzamides with methyl 2-trifluoromethylacrylate proceeds smoothly under rhodium(III) catalysis to produce trifluoromethyl-substituted isoindolinone derivatives. The catalyst system [CpERhCl2]2/AgSbF6 is effective for the oxidative coupling, while [Cp*RhCl2]2/AgSbF6 leads to their redox-neutral coupling predominantly. The oxidative coupling reactions with related acrylates have also been examined.
Bigels consist of a relatively new group of soft materials, developed using two or more networks to achieve synergistic multifunctionalities. Covalently crosslinked bi-hydrogels from two different polysaccharides were designed by employing a two-step process of crosslinking and drying. The individual hydrogels prepared by crosslinking with divinyl sulphone (DVS), were kept together and left to dry. The evaporation preceded the pendant DVS groups on the surface of the two hydrogels to react and bind. The finally obtained fused xerogel can be stored for a long time and used on demand as an uniaxially swelling bigel. We envision the potential use of such polysaccharide hydrogels to prepare cell-gel constructs or structurally compliant tissues as sensors.
We have synthesized and characterized an acceptor-π-donor-π-acceptor type pyridinium salt. The salt exhibited yellow emission with large Stokes shift in solution and was successfully excited by NIR irradiation via two-photon absorption process. In addition, it was found that the usage of the salt as a bioimaging agent for HeLa cells visualizes cell death. The combined use of the salt and a commercially available green fluorescent dye for the detection of live cell viability realized the one-shot fluorescence imaging of live and dead HeLa cells under the single blue excitation.
Ligand exchange reactions between a Hoveyda–Grubbs-type complex and 2-alkoxybenzylidene in a biomolecule assist in the delivery of a ruthenium complex unit to the biomolecule. Complexes having an electron-withdrawing group in their ligands efficiently transfer a ruthenium complex unit onto peptides. This method is also applicable for adenylate kinase, an experimental model protein. The ligand exchange reaction originates from ruthenium-olefin specific interactions and potentially provides a bioorthogonal method for chemical modification of biomacromolecules with transition metal complexes.
Conjugated polymer crystals enable us to realize an ideal platform for the highest density-of-state of electrons in valence and conduction bands. Herein we report a facile protocol to prepare crystalline particles (P3HT-CP) of poly(3-hexylthiophene) (P3HT) with clear cubic shapes. Long-range ordering of P3HT has been confirmed by microscopic techniques, suggesting extremely small contribution from amorphous domains in the cubic structures. The comparable electronic absorption spectra of P3HT-CP dispersion and the thin-film of P3HT-CP suggest the suppression of additional structural evolution during solvent evaporation and stable dispersion.
Third-generation cephalosporins possess broad spectrum and potent activities against Gram-positive and Gram-negative bacteria. In order to establish a general methodology for improving the oral bioavailability of third-generation cephalosporins, we designed and prepared a series of novel prodrugs of cefetamet using cefetamet pivoxil as a substrate by converting the amino group at the aminothiazole moiety into a series of acyloxymethyl carbamates. Several prodrugs showed higher oral bioavailability than an l-alanyl analogue of cefetamet pivoxil and comparable bioavailability to cefetamet pivoxil.
Macrocyclization can help improve pharmacological activity, metabolic stability, cell permeability and oral absorption to create better drug candidates. For example, enhancing the oral absorption of the compounds can allow a change in administration route. We tried to improve the oral bioavailability of ceftriaxone, a third-generation cephalosporin having a unique side chain with a 2,5-dihydro-6-hydroxy-2-methyl-5-oxo-as-triazin-3-yl group at the C-3 position of the cephem nucleus. We prepared novel macrocycles of ceftriaxone by valuable synthetic methods and confirmed their oral bioavailabilities.
The separation of oil-water mixtures has attracted widespread attention for addressing increased oil spillage and oil-polluted water. In this study, a novel and low-cost oil-water separation coating material composed of epoxy (EP) and modified sepiolite (SEP) by poly (diallyldimethylammonium chloride) (PDDA) and sodium perfluorooctanoate (SPFO) was fabricated. The as-prepared coating showed excellent superhydrophilic/superoleophobic properties, determined by its micro/nano rough microstructure, hydrophilic groups of PDDA, and oleophobic groups of SPFO, and it is not damaged by friction even after being wetted by water, which was mainly ascribed to EP with good adhesiveness. More importantly, the surface of stainless-steel mesh sprayed with SEP@PDDA-PFO/EP coating became superhydrophilic/superoleophobic, and showed excellent oil-water separation efficiency, which can avoid the deficits of traditional separation materials easily being polluted and difficult to recycle. This research could provide a novel modification method of SEP and promote its application in oil-water separation.
Due to the crucial impact of Li-ion batteries commercialized in 1991, the author had an opportunity to contribute to the research development of lithium battery materials beginning in 1997. These research experiences further provided motivation and opened up a new research field targeting the demonstration of non-aqueous Na-ion batteries later in the career. In 2009, the author’s research group successfully demonstrated 3-volt class charge and discharge of a Na-ion battery, and the increased motivation led to a brand-new 4-volt class K-ion battery. This article overviews our systematic studies of lithium-, sodium-, and potassium-driven redox systems, which synergistically induce accelerated development of new materials for next-generation rechargeable batteries. Our achievement update of layered oxide and hard carbon electrode materials is also described as an effort towards high-energy Na-ion batteries.