Hydroxy-sulfone 34b, prepared as a mixture of trans and cis isomers by condensing the O-silyl derivative 18c of 2-hydroxy-2-methyl-cyclobutanone 18b — the Norrish II photocyclisation product of 2,3-pentanedione 21 — and methyl phenyl sulfone 33 was found to rearrange selectively either to the cyclopropanic β-ketosulfone 37 or the isomeric methyl ketone 38 by using, respectively, the tosyl fluoride/DBU and the DAST reagent. The potential of this methodology has been illustrated by a synthesis of phytal 1 from geranylacetone 46, and by the preparation from 3,4-hexanedione 51 and prenol 56 — via the cyclopropanic β-ketosulfone 54 (X-ray) — of an advanced fragment of the juvenile hormone molecule 59.
A direct synthetic method for trisubstituted allenes from propargyl alcohol is provided; the synthesis proceeds via an oxaphosphetane intermediate. Functional groups such as formyl and pyridyl exhibited a degree of tolerance during reaction without any protection. The alcohol dimethylated at the propargyl position afforded two structural isomers, allene and 1,3-diene. The product ratio was considerably influenced by the solvent. Allene was predominantly obtained when the reaction was conducted in cyclohexane, and the ratio was inverted by changing the solvent to dichloromethane. The prepared (2-pyridyl)allene served as a substrate for the copper(I) catalyzed cyclization reaction to afford 3,3-dimethylindolizine-2-one.
Thermal solid-state reactions involving ionic-to-covalent bond transformation were achieved in the ionic molecular crystals of 1,8-bis[(pyridin-1-ium-1-yl)methyl]anthracene anthracene-1,8-dicarboxylate to produce the cyclic diester. The crystal structure given by X-ray diffraction analysis showed that the electrostatic interaction between the benzyl pyridinium cation and the carboxylate anion successfully works to locate these reaction sites close to each other and that there are channels for crystalline solvents and the liberated pyridine to escape. Thereby, the cyclic diester was selectively formed by the crystal-to-crystal reaction, which was proven by powder XRD profiles and optical microscopic and SEM images of the crystals before and after the reaction. This is the first thermal crystal-to-crystal condensation reaction. Another ionic molecular crystal of 1,8-bis[(pyridin-1-ium-1-yl)methyl]anthracene anthraquinone-1,8-dicarboxylate was also studied. Therein, the corresponding cyclic diester was also obtained, but the crystals were transformed to amorphous solid by the reaction.
Stimuli-responsive gold(I) chloride complexes were developed based on a diarsenic ligand, cis-1,4-dihydro-1,4-dimethyl-2,3,5,6-tetrakis(alchoxycarbonyl)-1,4-diarsinine (cis-DHDA). The crystals of the complexes showed intense luminescence due to the aurophilic interactions. Interestingly, methyl- and t-butyl substituted cis-DHDAs offered different stimuli-responsive behaviors accompanied with emission color changes. The crystal samples of the complexes with both ligands changed their emission colors by mechanical stimulus such as grinding in a mortar, but the effect of CH2Cl2-treatment for the recovery of the original emission was dependent on the substituent structures. Furthermore, only the crystals of the complex with t-butyl substituted cis-DHDAs showed vapochromic luminescence. These differences arise from steric hindrance of substituents at the ester groups. Relationship between chemical structure and emission behaviors was studied based on a simple ligand backbone.
Zeolites demonstrating better SCR of NOx performance due to wide temperature activity, hydrothermal stability and N2 selectivity have been identified under a joint research initiative by the Research Association of Automotive Internal Combustion Engines (AICE), Japan. Based on the AICE’s standards, over 25 zeolites with different structures and pore dimensions were investigated and their SCR efficiency and durability have been compared. While the performances of the top contenders cannot be related to a single parameter, the results suggest that the SAR, Cu quality/quantity, pore dimensions, diffusivity and acidity play a combined role in deciding the SCR activity and selectivity.
Microwave induced plasma in liquid has become a green and effective method for preparation of metallic nanoparticles (NPs). In our research, we have introduced yttrium oxide (Y2O3) coated stainless steel electrodes to address impurity problems of resulting NPs due to the loss of electrode materials. We have proposed using [Ag(NH3)2]+ complex as an alternative precursor and l-arginine as the stabilizing agent to synthesize highly uniform Ag NPs with an average diameter of around 5 nm. [Ag(NH3)2]+ complex was chosen as it can allow the reaction proceed at high pH for higher reaction yield compared with using AgNO3 whereas l-arginine can stabilize Ag NPs to attain highly uniform and small sizes. The influence of the selection of initial precursor on the reduction of metal precursor during the plasma irradiation, the particle size and size distribution of Ag NPs, and influence of the amount of l-arginine, were investigated.
A label-free amperometric immunosensor using Prussian blue as an artificial peroxidase to detect methamphetamine was developed. The immunosensor exhibited excellent stability even in neutral and weakly alkaline conditions. Platinum-Prussian blue (Pt-PB) hybrid film co-deposited on an electrode was coated with double-layer 2D-network 3-mercaptopropyl-trimethoxysilane (3-MPS), the thiols on which were utilized to absorb nano-Au in order to capture antibody. The Pt nanoparticle in the hybrid film acted not only as a carrier of PB to stabilize the PB film, but also a modifier for catalytic function because it increased the size of the lattice channels in PB film. Meanwhile, the double-layer 2D-network 3-MPS film could help stabilizing the Pt-PB film with its densely-packed structure and its homogeneous and defect-free characteristics. The signal readout was obtained electrochemically via PB-catalyzed H2O2 evolution reaction, which was inversely proportional to the concentration of methamphetamine in the sample. Thus, methamphetamine could be detected in 1.0 × 10−8 M–4.0 × 10−6 M by the immunosensor.
ESR measurements of [CLPOT-(4-X-TEMPO)] inclusion compounds (CLPOT = 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine, and 4-X-TEMPO = 4-substituted-2,2,6,6-tetramethyl-1-piperidinyloxyl radical) with 1D organic-radical molecular chains constructed in organic 1D nanochannels used as templates were conducted in the range of temperatures from 4.2 to 300 K. The peak-to-peak line width (ΔBpp) of all isotropic ESR spectra of the [CLPOT-(4-X-TEMPO)] was much narrower in the whole temperature range than the estimation based on the Van Vleck’s formula for the second moment of the rigid lattice model. In addition, the line profiles of all ESR spectra of the [CLPOT-(4-X-TEMPO)] became Lorentzian in the whole temperature range, compared with our previous results using tris(o-phenylenedioxy)cyclotriphosphazene (TPP) as templates in which the ESR profiles were temperature-dependent. These results indicate that the narrower ESR line width of the [CLPOT-(4-X-TEMPO)] may be caused not by motional narrowing but by 3D exchange interaction even at room temperature although the magnitude was less than 1 K.
The cyclocoupling of epoxides and CO2 was investigated using porphyrin-based Cu(II) metal-organic frameworks with 2D coordination networks. A variety of mono- and disubstituted epoxides were transformed into cyclic carbonates under mild and neat conditions. Several control experiments were carried out to elucidate that the catalytically active site is the dicopper paddle wheel unit rather than the copper porphyrin complex moiety. The proposed mechanism was corroborated by density functional theory calculations of a model paddle wheel unit.
Carbon capsules with mesoporous wall and hollow interior were used to fabricate the sensing thin films for volatile aromatic vapors. To grow the thin film based on convenient layer-by-layer (LbL) process, carbon capsules need precoating with surfactants to assist their dispersion into aqueous solution. The influence of the surface covered surfactants on the adsorption selectivity of the corresponding carbon capsule film on aromatic vapors is studied. The results showed that poly (styrene sulfonate) (PSS) which is mainly covered on the outer surface of carbon capsules may be of benefit for higher accessibility of vapors with benzonoid nature to the carbon surfaces. A more enhanced adsorption selectivity to aromatic vapors is thus achieved compared to the cases of (sodium dodecyl sulfonate (SDS) and poly(allylamine hydrochloride) (PAH)), which can be fully or partial filled into the pores of carbon capsule.
The cellulose-dissolving ability and some physical properties of mixed solvents of an amino acid IL, N-methyl-N-(2-methoxyethyl)pyrolidin-1-ium 2,6-diaminohexanoate ([P1ME][Lys]), with polar aprotic solvents, such as 1,3-dimethylimidazolidinone (DMI), N,N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), and acetonitrile (CH3CN), have been investigated. The viscosity was significantly reduced by the increasing content of polar aprotic solvents, and a 1:1 mixture (molar ratio) of [P1ME][Lys] with DMF showed 91.5 cP which corresponded to less than 1/10 compared to that of the pure IL at 25 °C (1058 cP). The β values of the mixed solvents, which have the IL contents over 0.1, exhibited β-values similar to that of the pure IL. On the other hand, the π-value was dependent on the ratio of the IL content, and the pure IL had the highest π-value. We found that the mixed solvent of [P1ME][Lys] with DMF (1:1) easily dissolved the cellulose and the mixed solvent could be used to extract cellulose from moso bamboo (Phylostachys heterocycla) powder. The efficiency of the extraction of cellulose from the bamboo powder was significantly increased when a 1:1 mixture of the IL with a polar aprotic solvent was used as the extracting solvent at 60 °C; the extraction ratio of the 1:1 mixture (IL: DMF) reached twice that of the pure IL. We thus obtained cellulose in 18% (w/w) yield from the bamboo powder.
Optical tweezers are powerful and flexible tools for manipulating micrometre-sized objects. Recently, metal nanostructures are gathering attention to trap nanometre-sized objects to utilize their plasmonic properties. Here, we discuss the preparation of gold nanocups (250-nm diameter) and their plasmonic properties for optical trapping. Gold was sputtered on a two-dimensional colloidal crystal (2DCC) and then de-coupled from the 2DCC via hydrofluoric acid etching, which resulted in a uniform gold nanocup array that was encapsulated in a flexible polymer resin. These nanocups in a resin can be transferred onto a variety of substrates. The optical trapping properties of gold nanocups are also discussed.
Recent advances in genome databases have allowed discovery of novel classes of natural products and their biosynthetic enzymes. Given the potentials and advantages of the biosynthetic enzymes, they are applicable to not only the production of natural products but also synthesis and discovery of artificial molecules with desired functions. This account describes our recent efforts to develop artificial in vitro biosynthesis systems that potentially allow for the elaboration of pseudo-natural peptides with novel bioactivities.
Ion-pairing assemblies consisting of appropriately designed π-electronic ionic species afford various functional supramolecular assemblies including crystals and soft materials based on the anisotropic orientation of π-electronic ionic species through electrostatic and other weak noncovalent interactions. Organized assemblies comprising π-electronic ionic species as dimension-controlled assemblies provide unique and tunable mesophases and electronic properties. As components of dimension-controlled ion-pairing assemblies, π-electronic ion pairs are important and have been prepared through (i) synthesis of π-electronic units bearing ionic substituents, (ii) synthesis of genuine π-electronic ions, and (iii) complexation of π-electronic receptors and ions. In (ii) and (iii), appropriate ion-exchange processes are necessary. Based on these strategies, fascinating ion pairs and their assemblies have been constructed, resulting in an elucidation of the assembling behaviors of π-electronic ion pairs. In this article, ion-pairing assemblies consisting of precisely designed π-electronic ionic species are described, with a focus on the preparation methods, structures, and properties.
Soot oxidation over CeO2–ZrO2 (CZ) has been studied herein. The soot-CZ mixtures were observed under different contact conditions using transmission electron microscopy (TEM) and evaluated using thermogravimetric-differential thermal analysis (TG-DTA). These results indicate that the soot ignition temperature depends on the soot/CZ contact degree, and the soot oxidation rate depends on the soot/CZ contact area. The TEM observation of soot-CZ mixture quenched at T50 (50% soot conversion) indicates that soot oxidation occurs only at the soot/CZ interface. Furthermore, the soot oxidation under 18O2 flow and under He flow suggests that CZ lattice oxygen is a more active oxygen species than the adsorbed oxygen on the CZ. The CZ lattice oxygen mainly oxidizes soot; however, the adsorbed oxygen on the CZ surface does not oxidize soot at lower temperatures. Thus, the adsorbed oxygen oxidizes the reaction intermediates such as adsorbed CO on the CZ surface, which shows that CZ lattice is more active than the adsorbed oxygen.
E,E-1,4-Bis(2,4-ditrifluoromethylstyryl)benzene (d24CF3) and E,E-1,4-bis(3,5-ditrifluoromethylstyryl)benzene (d35CF3) were synthesized. The d35CF3 crystals grown from solution displayed a unique fibrous form and emitted propagated fluorescence, and a d35CF3 film demonstrated a very low ionization potential of −6.7 eV. Meanwhile, d24CF3 crystals exhibited aggregation-induced emission.
Fluorescent metal nano-clusters with size-dependent properties have emerged as the next generation fluorophores with versatile applications. In this article, we give a brief overview on three fluorescent metal nano-clusters, (gold, silver and copper). Because of their non-toxicity and solubility in water they are highly suitable for biological systems and in particular, live cell imaging. We show that they may be used for distinguishing cancer and non-cancer cells and selective killing of cancer cells. We also discuss their effect on enzyme catalysis.
This review describes the utilization of M13 phage, one of the filamentous viruses, for the development of novel functional soft materials. Traditionally, M13 phage has been widely used as a scaffold to display peptides or proteins on the surface of M13 phage through genetic engineering. This technology is well known as “phage display”, and generally used nowadays for the construction of peptide or protein libraries on M13 phage surfaces to identify peptides or proteins with desired functions. Recently, construction of hierarchical assembled structures composed of M13 phage as a building block has generated great interest as a means of using the excellent properties of M13 phage for the development of novel classes of soft materials. In this case, liquid crystalline formation of M13 phage is effectively used to fabricate structurally regulated assemblies. Further combination of the phage display technique and liquid crystalline formation widely expands the applicability of M13 phage to various fields such as devices, sensors, and biomedicines. Such approaches to M13 phage should contribute to novel attractive opportunities for next-generation soft materials for science and technology.
Protonic defects function as “lost positive point charges”, and their inclusion in molecules has great potential to control the total charge of a system. In other words, they have the ability to work as a dopant for hole injection. Carrier generation occurs when we confine and stabilize the protonic defects in hydrogen-bonding networks co-existing with a tetrathiafulvalene (TTF) skeleton, affording pure organic conductors without an addition of external dopant or electrochemical oxidation. Their conductivity varies in the range of six orders of magnitude from 10−4 to 102 S/cm, corresponding to molecular design. Moreover, anomalous isotope effects are observed in some electronic properties such as conductivity and thermopower, etc. In this account, the concept, molecular design, carrier generation and electronic properties of a series of the protonic-defect induced pure organic conductors are comprehensively reviewed from semiconductors to organic metals.
Co3O4-loaded TiO2 is a photocatalyst capable of oxidizing water into O2 by absorbing an entire range of visible light (400 < λ < 850 nm). In this work, the photocatalytic activity for water oxidation was investigated with respect to crystal phase, specific surface area, and surface morphology of TiO2 support. Results of photocatalytic reactions using six different TiO2 samples that possessed single-phase anatase or rutile structure indicated that the activity could be improved by applying a TiO2 support that had larger specific surface area, because it could accommodate larger amount of Co3O4 with minimal impact of undesirable aggregation. It was also suggested that when the specific surface area is similar, the activity is largely insensitive to crystal phase of TiO2, but is influenced by the surface morphology of TiO2, which can affect the dispersion of Co3O4.
Energy storage systems for powering electronic medical implants and sensors are essentially based on conventional electrode materials and electrolytes. Because of their toxicity, these battery systems need special encapsulation, which leads to bulky devices. Batteries based on biocompatible electrodes and electrolytes overcome these limitations and hold promise as viable alternatives for powering medical implants and devices. The present review aims at giving an overview of possible battery systems and current performance. It also gives a summary of battery architectures and their fabrication, with a focus on potential miniaturization. Advances in biocompatible batteries are expected to have not only a large impact on electronic medical implants and point-of-care monitoring systems, but also for environmental sensing and transient electronics.