Molecules with two orthogonally oriented π-systems (cruciforms) have attracted interest by virtue of the different conjugation pathways that exist between the individual parts of the molecule. In particular, the possibility for changing the conjugation pathways by an external stimulus may provide controllable molecular switches for molecular electronics. Here we highlight our design and synthesis of cruciform molecules incorporating the redox-active unit tetrathiafulvalene (TTF) placed vertically to an oligo(phenyleneethynylene) (OPE) unit. These molecules have potential as redox-controlled wires (transistors) for molecular electronics. The OPE–TTF cruciforms are prepared by a combination of stepwise metal-catalyzed cross-coupling and Wittig reactions.
Here we highlight our design and synthesis of cruciform molecules incorporating the redox-active unit tetrathiafulvalene (TTF) placed vertically to an oligo(phenyleneethynylene) (OPE) unit. These molecules have potential as redox-controlled wires (transistors) for molecular electronics.
Several key issues of aqueous lithium/air rechargeable batteries that consists of a water-stable lithium electrode, an aqueous electrolyte, and a bifunctional air electrode are reviewed. Based on research and discussion of these issues, the challenges and prospects for high energy density aqueous lithium/air rechargeable batteries are described. From a broader perspective, lithium/air rechargeable batteries that employ aprotic electrolytes are also briefly introduced for comparison.
We have designed a new apparatus, an electrochemical SFA, for measuring the forces between symmetric gold electrode surfaces under electrochemical potential control. The surface separation was determined by two-beam (twin-path) interferometry. The potential was applied to the gold surfaces (working electrode) in 1 mM aqueous KClO4 using Ag/AgCl as the reference and Pt as the counter electrode. We observed the van der Waals attraction and the double layer repulsion which decreased with the increasing potential from −0.1 to 0.2 V (vs. Ag/AgCl).
An online ultrasensitive method for detection of nickel ions by capillary electrophoresis–post chemiluminescence with field-amplified sample injection has been developed. Under the optimal conditions, the detection limit for Ni2+ was 1.0 × 10−14 mol L−1, relative standard deviations of peak area and migration time using 1.0 × 10−12 mol L−1 Ni2+ (n = 7) were 6.23% and 2.86%, respectively. This is a lower detection limit for Ni2+ than previously reported. The proposed method was successfully applied to the separation of Hg2+, Ni2+, and Cu2+ in a mixture.
Electrochemically generated ArS(ArSSAr)+ was found to be an effective activator for glycosylation of thioglycosides. Efficiency of the reaction strongly depends on the nature of the counter anion, and B(C6F5)4− was the most effective among those examined. The method was applicable to various glyocosyl donors including thiogalactosides and thiomannosides and various acceptors including those having secondary hydroxy groups.
Speciation of iron (Fe) precipitated on bacterial stalks was studied by Fe K-edge µ-XRF-XAFS. Micro-XRF analysis of the stalk samples showed that Fe is precipitated around the stalk. All the µ-XANES spectra at several Fe-accumulated parts showed similar spectra. This study indicated that synchrotron µ-XRF-XAFS is a powerful tool for chemical speciation of metals at single-cell level for bacteria bearing metal.
The efficient decomposition of environmentally persistent perfluorooctanoic acid (PFOA) was achieved by a hybrid of electrolysis and photocatalysis. The rate constant of PFOA decomposition in the hybrid system was larger than the sum of the constants in electrolysis-only and photocatalysis-only systems. The hybrid system was able to accelerate the PFOA decomposition by complementally support of two kinds of reaction kinetics. These results could be useful for development of a new continuous system for practical treatment of waste water containing perfluorinated acids.
Titanate nanosheets with a lamellar mesostructure were developed using the lamellar self-assembly of cationic 1,12-dodecanediamine (DDA) as a template. An electrostatic interaction between negatively charged titanate nanosheets and positively charged DDA molecules was required to form layered titanate nanosheets. This approach leads to titanate nanosheet surface characteristics such as visible light absorption and high adsorption of hydrophobic organic compounds.
The origin of the difference of melting points (Tm) between tertiary and quaternary ammonium triflates has been investigated by ab initio and molecular dynamics simulations. Experimentally, Tm of tertiary ammonium triflates are lower than those of quaternary ammonium triflates. In this work, we used [N122H][TfO] and [N1113][TfO] as typical models of tertiary and quaternary ammonium triflates, and the mutual arrangement of these cation–anion pairs were discussed to elucidate the difference of the melting points of these systems.
The relationship between synthesis conditions of iron-containing mesoporous silica (Fe-MCM-41) and UV–visible absorbance was studied. Fe-MCM-41 with high UV absorption and low visible absorption was effectively synthesized by using [Fe(acac)3] as an iron source and employing calcination for the template removal. The obtained Fe-MCM-41 did not exhibit photocatalytic activity as determined by dye decomposition, and its SPF and PA values were at an acceptable level, concluding that there is a possibility as a new sunscreen agent.
Cobalt(III) complexes with N-(aminoalkyl)salicylamide dianions, Ln2− (n = 1–4), have been prepared and their molecular and crystal structures have been determined. The geometric (mer- or fac-) selectivity of [Co(Ln)2]− complexes was dependent on the number of the amine–amidato chelate ring member. Intermolecular homochiral hydrogen-bonds and solvatochromic behavior of the complexes were also observed.
There is increasing interest in nanostructures and in the molecular design of building blocks which self-assemble into nanoscaled intelligent materials. We outline a method for controlling the nanostructures of amphiphilic nonapeptides by changing the pH of the aqueous medium. A lysine residue on the hydrophilic face of the peptide plays a critical role as a morphology-control unit. This self-assembling peptide may, therefore, find application as a template for peptide-directed biomineralization.
Conversion of pinacol arylboronic esters 3 to aryl triolborates 5 via transesterification with 1,1,1-tris(hydroxymethyl)ethane (4) was established with the advantages of tolerance to various functional groups. Transesterification was carried out at 30–60 °C in dioxane in the presence of MOH (M = Na and K) and H2O. High yields were achieved for stable aryl triolborates 5.
Novel heterostructured nanoparticles were synthesized by the deposition of Ag on Pt nanocubes by overcoming lattice mismatch, where Ag deposition preferentially occurred at corners of Pt nanocubes during the initial stage of deposition, and position and amount of Ag deposition were controlled by tuning of reaction conditions. The mechanism of such site-specific deposition of Ag is discussed in relation to I− (shape forming agent) and succinate (organic protective agent).
C-type cubic (Yb1−xTbx)2O3±δ (0 ≤ x ≤ 0.62) catalysts were synthesized by coprecipitation. Among the samples prepared, (Yb0.50Tb0.50)2O3±δ showed the highest catalytic activity and high tolerability for O2 or CO2 coexistence was recognized. In particular, the negative effect of CO2 on the NO decomposition activity is significantly reduced compared to those of conventional catalysts, and N2 yield as high as 33% was obtained even in the presence of 5 vol % CO2.
Nanospheres formed by self-assembly of trigonal glutathione (TG) underwent disulfide recombination upon addition of dithiothreitol. Guest molecules encapsulated in the nanospheres were gradually released during the recombination process.
A novel tribenzotetraazaporphyrin with a fused azulene ring was synthesized via mixed condensation reaction of 5,6-dicyanoazulene and 3,6-dibutoxyphthalonitrile. The macrocycle exhibited several intense absorption peaks from 600 to 900 nm. The spectroscopic properties were analyzed by DFT calculations.
We provide evidence that a heteroleptic double-decker complex of Ce with phthalocyanine and porphyrin ligands undergoes rotational libration in solution for the first time on the basis of variable-temperature 1H NMR. On the other hand, the Zr complex with the same set of ligands undergoes no rotational motion. These molecules deposited on graphite surfaces exhibited different shapes in STM images, revealing difference in the rotational motion at the molecular level.
To develop a molecular imaging probe for potassium cation based on the chemical shift change of 19F magnetic resonance (MR), thrombin aptamer, whose structure was changed with the selective binding of potassium cation, was labeled with a fluorine compound. We demonstrated that the probe could detect potassium cation by chemical shift change of the 19F MR signal, and that the chemical shift change was caused by potassium cation selective G-quadruplex formation.
Novel pentacyclic ladder oligomethylsilsesquioxane was synthesized using cis,trans,cis-[MeSi(NCO)O]4 as a building block. This compound was isolated in 13% yield by reprecipitation from the reaction mixture. X-ray crystallography revealed that pentacyclic rings assume a syn,anti,syn-configuration, resulting in the tube-like structure.
Band gap controllable, water-soluble, and π-conjugated polymers were prepared by the addition–condensation of pyrrole (Py), 1,2,3-trihydroxybenzene (THB), and sodium o-formylbenzenesulfonate (BS) with different Py/THB/BS ratios. Band gap values are continuously controlled from 0.3 to 1.1 eV in aqueous solutions by changing molecular weights and monomer unit sequences.
Bent bridging ligands appending dendrons (G-1, G-2, and G-3) at their concaves are complexed with Pd(II) ions to self-assemble into M12L24 spherical shells confining inversely branched dendrimers. Their structures were fully characterized by NMR, CSI-TOF-MS, and AFM.
Novel azaacridine analogues were synthesized and their antiproliferative activities against K562 and HepG-2 cell lines were evaluated, among which compound 5a was found to display good cytotoxicity. UV–visible spectral absorbance measurements showed that 5a can bind with calf thymus DNA (ct DNA). A relaxation assay indicated that 5a inhibits topoisomerase 1 activity.
The thermodynamics of the exchange of solubilizers adsorbed on single-walled carbon nanotubes (CNTs) is probed by analysis of the spectral shifts of the CNTs in the near-infrared region. Equilibrium constants and thermodynamic parameters of the exchange of sodium cholate for DNA (20-mers of oligo DNAs, cytosine) on CNTs of different chirality are determined.
A new high-pressure phase transition of pyridine at 5.0 GPa was found using Raman and IR spectroscopy. Application of pressure over 20 GPa induced irreversible polymerization of pyridine, and a yellow-brownish solid material was recovered at ambient condition. The X-ray diffraction pattern revealed that the recovered solid material contained a crystalline phase in contrast to amorphization of other aromatic compounds in a similar pressure region.
A series of aliphatic waterborne polyurethane (WPU) dispersions with high ionic concentration were synthesized by prepolymer mixing. The resultant structure–property relationships were investigated. It was revealed that there was a new microphase besides the phase separation between the soft and the hard domains. The new microphase separation found in the hard domains was formed by aggregation of the ionic groups characterized by dynamic mechanical analysis, FTIR characterization, and thermal gravimetric analysis.
Acetetracenylene-1,2-dione was synthesized by double Friedel–Crafts acylation of tetracene with oxalyl chloride in 46–54% yield. Photophysical, electrochemical, and thermal analysis of the compound revealed its band gap (Eg = 1.77 eV for the solid state), electron-accepting nature (Epcred = −1.35 V vs. Fc/Fc+), and thermal stability (Tdecomp > 300 °C). Single crystals were successfully grown by physical vapor transport, and parallel π-stacking of the molecules was observed by X-ray crystallography.
G3-6βCD32, which has 32 β-cyclodextrins functionalized on the surface of a polyamidoamine dendrimer, was prepared as a multivalent host molecule. G3-6βCD32 showed selective recognition behaviors for guest polymers. Using guest recognition sites on the surface, a supramolecular bilayer sphere was prepared in aqueous solutions. The molecular recognition properties and structure of G3-6βCD32 are reminiscent of a virus structure.
A simple and efficient method for the synthesis of some hitherto unreported pyrimidine-annelated spiro-heterocycles via 5-endo mode iodocyclization has been described. The reaction is an example of iodocyclization of 1,5-enynes which proceeds in the absence of base and affords the products in excellent yields.
A coin cell battery is fabricated using triquinoxalinylene as a cathode active material and a lithium metal anode. The first discharge curve shows a remarkably large capacity (420 A h kg−1), which corresponds to a six electron migration in the first charge. However, repeating the charge–discharge until the 15th cycle gradually decreases the capacity, but after that the capacity remains constant with a value of 220 A h kg−1. This large value remains even after 100 cycles. Additionally, the use of a tribromo-substituted derivative gives a large discharge capacity (≈250 A h kg−1) due to a comparatively stable six electron migration from the first charge–discharge cycle.
A novel, sensitive, and highly selective fluorescent probe which contains 2-(2-hydroxyphenyl)benzimidazole receptor groups has been prepared for detecting glutathione (GSH) that operates under aqueous conditions. The complex of the fluorescent compound with copper(II) ion was selectively responsive to GSH and induced a recovery of blue fluorescence.
A novel heavy fluorous thioglycoside 6 was developed and applied to oligosaccharide synthesis. The fluorous thioglycoside 6 was readily prepared via the corresponding fluorous thiol. Synthesis of the LacdiNPhth derivative was briefly achieved with a single-column chromatographic purification by using a heavy fluorous tag method. Additionally, the fluorous tag was recovered as fluorous alcohol 1 in high yield.
Rotaxanes are considered to be prototype molecular machines bearing a rotor and an axis within a molecule. In our study on complex formation of modified α-CDs as host molecules for guest molecules consisting of an alkyl chain with pyridyl end caps, we observed control of complex formation and dissociation by pH responses of functional groups on modified α-CDs.
A mesoporous sulfated zirconia–silica material with high hydrothermal stability was prepared by a two-step hydrothermal treatment process in a pH range of 1.65–3. This material still showed high surface area, large pore volume, and uniform structure after steam treatment at 800 °C for 5 h. In cumene cracking, the material exhibited relatively steady catalytic activity even after steam treatment at 600 °C for 2 h.
Polycondensation reaction of 1,3-dimethoxybenzene and TeCl4 was performed at a feed ratio of 1,3-DMB/TeCl4 = 1/10 without catalyst in 1,4-dioxane at 60 °C for 48 h, affording poly(1,3-DMB-co-Te) with Mn = 45100 and Mw/Mn = 1.89 in 75% yield, with release of HCl. 1H NMR, IR, and X-ray fluorescence spectroscopy indicated that poly(1,3-DMB-co-Te) had a partially branched skeleton. This polymer had good solubility, good film-forming ability, high thermal stability, and a high refractive index (1.769 at 0.6328 µm).
The magnetic alignment of poly(L-lactic acid) (PLA) containing octamethylenedicarboxylic dibenzoylhydrazide (OMBH) as a nucleating agent was studied. OMBH also affected PLA as a nucleating agent when about 5 wt % of d-type material was included. The magnetic alignment of PLA including OMBH was achieved. The c axis of the PLA was parallel to the magnetic field.
Ultrastable aqueous graphite nanofluids were prepared by single-step liquid-phase pulsed laser ablation (LP-PLA), and they showed an outstanding long-term stability without any agglomeration, even though no surfactant was used. It was revealed with FT-IR spectroscopy that the hydrophilic functional groups were introduced onto the surface of graphite nanoparticles and that such hydrophilic nature showing a high negative ζ potential was the origin of the outstanding long-term stability. Finally, aqueous graphite nanofluids demonstrated an enhanced thermal conductivity by 1.49% with low concentration (0.02 vol %), compared to pure water.
The asymmetry of (GaAs)1−x(Ge2)x band gap bowing, as a function of Ge concentration, is investigated by ab initio calculations. We show that the nature of the chemical bonds violating the octet rule in such alloys is affected by the local geometry: the switching of the cluster type between Ge to GaAs domain at Ge concentration of about 0.3 plays a fundamental role in the final asymmetry.
Nanosized neck-structured α-Fe2O3 nanoparticles were prepared successfully from iron(II) chloride tetrahydrate solely by hydrothermal method. FE-SEM and TEM studies revealed a unique necked structure with a particle size of ca. 50–60 nm. The synthesized nanomaterials showed excellent colloidal stability and magnetization ability. Finally, the as-prepared α-Fe2O3 nanoparticle suspensions showed almost 100% cancer cell killing by the significant temperature increment when an AC (alternating current) magnetic field and photoirradiation were applied at a concentration of 80 µg mL−1 MEM (minimum essential medium).
A fluorescence lifetime measurement was performed for monitoring the viscosity of a confined liquid (glycerol) film between mica surfaces using a cyanine dye, Cy1, as a viscosity probe at various film thicknesses. The fluorescence decay curve consisted of two components, i.e., one attributed to the Cy1 in the central part of the liquid between the surfaces and another to the Cy1 adsorbed on the surfaces. The increased lifetime of the former indicated the increase in the viscosity of the confined liquid.