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We present a strategy for enhancing Li + conduction in block copolymer electrolytes by introducing trace amounts of Li salts into polystyrene- b -poly(ethylene oxide) (PS- b -PEO), wherein Li + ions preferentially coordinate with the -OH end groups of the PEO chains, resulting in the formation of double primitive cubic ( Im 3̅ m ) structures. Compared with TFSI - anions in Li salts, smaller anions (PF 6 - and BF 4 - ) could facilitate ion localization more effectively, expanding the salt concentration range for developing stable Im 3̅ m structures. The Im 3̅ m structures formed in PS- b -PEOs doped with LiBF 4 at r = 0.013-0.02 ( r ≡ [Li + ]/[EO]) exhibited ionic conductivities several times higher than those doped at the conventional level (e.g., r = 0.06). The corresponding morphology factors were more than eight times higher than those of the lamellar-forming electrolytes. Notably, the activation energy value for Li + conduction in PS- b -PEO with one Li + ion per entire PEO chain was only 0.012 eV (by Vogel-Fulcher-Tammann), indicating that Li + transport was less dependent on polymer relaxation. Furthermore, modifying the PEO chain ends with three -PO 3 H 2 groups further strengthened the Li + -mediated end-end interactions and significantly extended the salt concentration range to form Im 3̅ m structures. In contrast, increasing the number of -OH end groups (such as diols and triols) had minimal effect on stabilizing the network morphologies.

Assembling solution-processed van der Waals ( vdW ) materials into thin films holds great promise for constructing large-scale, high-performance thin-film electronics, especially at low temperatures. While transition metal dichalcogenide thin films assembled in solution have shown potential as channel materials, fully solution-processed vdW electronics have not been achieved due to the absence of suitable dielectric materials and high-temperature processing. In this work, we report on all-solution-processed vdW thin-film transistors (TFTs) comprising molybdenum disulfides (MoS 2 ) as the channel and Dion-Jacobson-phase perovskite oxides as the high-permittivity dielectric. The constituent layers are prepared as colloidal solutions through electrochemical exfoliation of bulk crystals, followed by sequential assembly into a semiconductor/dielectric heterostructure for TFT construction. Notably, all fabrication processes are carried out at temperatures below 250 °C. The fabricated MoS 2 TFTs exhibit excellent device characteristics, including high mobility (>10 cm 2 V -1 s -1 ) and an on/off ratio exceeding 10 6 . Additionally, the use of a high- k dielectric allows for operation at low voltage (∼5 V) and leakage current (∼10 -11 A), enabling low power consumption. Our demonstration of the low-temperature fabrication of high-performance TFTs presents a cost-effective and scalable approach for heterointegrated thin-film electronics.

The investigation of twist engineering in easy-axis magnetic systems has revealed remarkable potential for generating topological spin textures. Implementing twist engineering in easy-plane magnets, we introduce a novel approach to achieving fractional topological spin textures, such as merons. Through atomistic spin simulations on twisted bilayer magnets, we demonstrate the formation of a stable double Meron pair, which we refer to as the "Meron Quartet" (MQ). Unlike a single pair, the merons within the MQ exhibit exceptional stability against pair annihilation due to the protective localization mechanism induced by the twist that prevents collision of the Meron cores. Furthermore, we showcase that the stability of the MQ can be enhanced by adjusting the twist angle, resulting in an increased resistance to external perturbations such as external magnetic fields. Our findings highlight the twisted magnet as a promising platform for achieving merons as stable magnetic quasiparticles in van der Waals magnets.

Twist engineering of van der Waals magnets has emerged as an outstanding platform for manipulating exotic magnetic states. However, the complicated form of spin interactions in the large moiré superlattice obstructs a concrete understanding of such spin systems. To tackle this problem, for the first time, we developed a generic ab initio spin Hamiltonian for twisted bilayer magnets. Our atomistic model reveals that strong AB sublattice symmetry breaking due to the twist introduces a promising route to realize the novel noncentrosymmetric magnetism. Several unprecedented features and phases are uncovered including the peculiar domain structure and skyrmion phase induced by noncentrosymmetricity. The diagram of those distinctive magnetic phases has been constructed, and the detailed nature of their transitions analyzed. Further, we established the topological band theory of moiré magnons relevant to each of these phases. By respecting the full lattice structure, our theory provides the characteristic features that can be detected in experiments.

Charged block copolymers are promising materials for next-generation battery technologies and soft electronics. Although once it was only possible to prepare randomly organized structures, nowadays, well-ordered charged block copolymers can be prepared. In addition, theoretical and experimental analyses of the thermodynamic properties of charged polymers have provided insights into how to control nanostructures via electrostatic interactions and improve the ionic conductivity without compromising mechanical strength, which is crucial for practical applications. In this Account, we discuss methods to control the self-assembly and ion diffusion behavior of charged block copolymers by varying the type of tethered ionic moieties, local concentration of embedded ions with controlled electrostatic interactions, and nanoscale morphology. We discuss with particular emphasis on the structure-transport relationship of charged block copolymers using various ionic additives to control the phase behavior electrostatically as well as the ion transport properties. Through this, we establish the role of interconnected ionic channels in promoting ion-conduction and the importance of developing three-dimensional interconnected morphologies such as gyroid, orthorhombic Fddd (O 70 ) networks, body-centered cubic (bcc), face-centered cubic (fcc), and A15 structures with well-defined interfaces in creating less tortuous ion-conduction pathways. Our prolonged surge and synthetic advances are pushing the frontiers of charged block copolymers to have virtually homogeneous ionic domains with suppressed ion agglomeration via the nanoconfinement of closely bound ionic moieties, resulting in efficient ion conduction and high mechanical strength.Subsequently, we discuss how, by using zwitterions, we have radically improved the ionic conductivity of single-ion conducting polymers, which have potential for use in next-generation electrochemical devices owing to the constrained anion depletion. Key to the improvement stems from hierarchically ordered ionic crystals in nanodomains of the single-ion block copolymers through the self-organization of the dipolar/ionic moieties under confinement. By precisely tuning the distances between ionic sites and the dipolar orientation in the ionic domains with varied zwitterion contents, unprecedented dielectric constants close to those of aqueous electrolytes have been achieved, leading to the development of high-conductivity solid-state single-ion conducting polymers with leak-free characteristics. Further, using these materials, low-voltage-driven artificial muscles have been prepared that show a large bending strain and millisecond-scale mechanical deformations at 1 V in air without fatigue, exceeding the performance of previously reported polymer actuators. Finally, smart multiresponsive actuators based on tailor-made charged polymers capable of programmable deformation with high force and self-locking without power consumption are suggested as candidates for use in soft robotics.

To fulfill the insatiable demand for wearable technologies, ionic electroactive polymer actuators have been entrenched as promising candidates that can convert low-input-voltage energy into high mechanical throughput. However, a ubiquitous trilayer design of actuators allows exclusively bending deformation and their highly nonlinear response restricts the true potential of low-voltage actuators for next-generation technology. Herein, we report an unprecedented multilayer design for soft actuators that enables complex deformations shown by skeletal muscles, mechanoreceptors, and plant roots in response to various environmental stimuli. Hierarchically ordered pores in a stretchable interlayer provide excellent electromechanical properties and fast charging kinetics, which enable linear motion by soft actuators at 3 V and under ambient conditions. Our actuators demonstrate astonishing levels of performance, including a 6.5% linear actuation strain, 0.8 s rapid switching speed, and 5000 cycle stable performance in air, producing a 4.2 mN linear blocking force at a ±3 V alternating square-wave voltage. This actuator design demonstrating a walkable spider capable of controlled back-and-forth propelling motion at low driving voltages provides the platform to envision a complex functionality using a portable battery as a power source for soft robotics, wearable exosuits, and biomimetic technologies.

Scientific research on advanced polymer electrolytes has led to the emergence of all-solid-state energy storage/transfer systems. Early research began with acid-tethered polymers half a century ago, and research interest has gradually shifted to high-precision polymers with controllable acid functional groups and nanoscale morphologies. Consequently, various self-assembled acid-tethered block polymer morphologies have been produced. Their ion properties are profoundly affected by the multiscale intermolecular interactions in confinements. The creation of hierarchically organized ion/dipole arrangements inside the block copolymer nanostructures has been highlighted as a future method for developing advanced single-ion polymers with decoupled ion dynamics and polymer chain relaxation. Several emerging practical applications of the acid-tethered block copolymers have been explored to draw attention to the challenges and opportunities in developing state-of-the-art electrochemical systems.

We herein developed an iontophoretic transdermal drug delivery system for the effective delivery of electrically mobile drug nanocarriers (DNs). Our system consists of a portable and disposable reverse electrodialysis (RED) battery that generates electric power for iontophoresis through the ionic exchange. In addition, in order to provide a drug reservoir to the RED-driven iontophoretic system, an electroconductive hydrogel composed of polypyrrole-incorporated poly(vinyl alcohol) (PYP) was used. The PYP hydrogel facilitated electron transfer from the RED battery and accelerated the mobility of electrically mobile DNs released from the PYP hydrogel. In this study, we showed that fluconazole- or rosiglitazone-loaded DNs could be functionalized with charge-inducing agents, and DNs with charge modification resulted in facilitated transdermal transport via repulsive RED-driven iontophoresis. In addition, topical application and RED-driven iontophoresis of rosiglitazone-loaded DNs resulted in an effective antiobese condition displaying decreased bodyweight, reduced glucose level, and increased conversion of white adipose tissues to brown adipose tissues in vivo . Consequently, we highlight that this transdermal drug delivery platform would be extensively utilized for delivering diverse therapeutic agents in a noninvasive way.

The performance limits of conventional super engineering plastics with inorganic nanofillers are surpassed by all-organic nanocomposites prepared via in situ S N Ar polymerization of polysulfone (PSU) in the presence of a highly dispersed aramid nanofiber (ANF) solution. The latter is directly used, bypassing the energy-consuming, nanostructure-damaging workup process. Using only a 0.15 wt % nanofiller, the all-organic nanocomposite shows an ultimate tensile strength 1.6× higher and 3.4× tougher than neat PSU and its blending counterpart due to the mutually interactive filler and maximally homogenized matrix. The exceptional toughness of the ANF/PSU nanocomposite originates from the grafted PSU on the surface of ANF; it drives stress-delocalized deformation, as revealed by stress-absorbable viscoelastic behavior and ductile elongation of materials. This material is a promising candidate for use as a filler-interactive, high-performance nanocomposite.

MoS 2 are two-dimensional (2D) materials that exhibit emerging photoluminescence (PL) at the monolayer level and have potential optoelectronic applications. Monolayers of MoS 2 typically achieved by mechanical exfoliation (Me), chemical vapor deposition (CVD), and chemical exfoliation (Ce) via lithium intercalation contain numerous defects that significantly reduce their PL efficiency. Several studies have reported overcoming poor PL in mechanically exfoliated and CVD-grown MoS 2 , but such studies for chemically exfoliated MoS 2 (Ce-MoS 2 ) have not been reported. Here, we report a solution-based method of enhancing the PL of Ce-MoS 2 by reacting with molecules with suitable functional groups at high temperatures. Reaction with dodecanethiol (DDT) generates PL that is more intense than mechanically exfoliated MoS 2 (Me-MoS 2 ) with high crystallinity and has a significantly broader range of wavelengths. Based on ultraviolet-visible, Fourier transform infrared, X-ray photoemission, and PL spectroscopy as well as transmission electron and PL imaging, we propose that the present method modifies PL properties of Ce-MoS 2 by simultaneously annealing, replacing molybdenum-oxygen with molybdenum-sulfur bonds, inducing strain, and generating a nanopolycrystalline structure. This work points to such defect engineering using molecules as an effective means to modify the properties of Ce-MoS 2 and layered transition-metal dichalcogenides more generally.

Polymerizing monomers on an atomically flat solid surface and air/water, solid/liquid, or liquid/liquid interface is now a rapidly emerging frontier. Dimension-controlled synthesis of π-conjugated polymers is of particular interest, which can be achieved by precise control of monomer distribution during the polymerization. The surface of ice allows rapid polymerization of monomers in the plane direction along the air-water interface to yield large-area two-dimensional sheet-like poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (2D sheet-like PEDOT:PSS) films with a thickness of ca. 30 nm. The persuasive role of ice chemistry is reflected in the high degree of crystallinity and superior conductivity of resultant PEDOT:PSS films. Excellent photoelectrochemical features were further disclosed when the ice-templated PEDOT:PSS films were coupled to quantum dots. Utilization of these polymer films in photovoltaic devices also resulted in excellent current density and power conversion efficiency. This work presents an innovative material technology that goes beyond traditional and ubiquitous inorganic 2D materials such as graphene and MoS 2 for integrated electronic applications.

Miktoarm star copolymers composed of three poly(ethylene oxide) (PEO) arms connected to one polystyrene (PS) chain, i.e., PS-(PEO) 3 , demonstrated synergistic improvements in the ionic conductivity and mechanical strength by factors of 2-30 compared to those shown by PS-PEO diblock copolymers. Entropic constraints for the chain stretching of (PEO) 3 gave rise to notably reduced domain sizes of PS-(PEO) 3 electrolytes, compared with the values of PS-PEO analogues. Further, the melting transition of PS-(PEO) 3 with PEO molecular weight of M n = 2 kg mol -1 was vanished with lithium salt doping at [Li]/[EO] = 0.06 under such confinements, resulting in an order of magnitude increase in the room temperature conductivity. The fact that lithium ion transport in PEO-based copolymers can be tunable by the way PEO chains are connected to hard polymers can lead to innovative designs for solid-state polymer electrolytes.

Notwithstanding the notable progress in the synthesis of N-heterocyclic carbene-stabilized radicals, aminyl radicals, supported by NHCs or otherwise, have been scarcely studied due to synthetic challenges. Triazenyl radical is a particular form of aminyl radical that contains three adjacent nitrogen atoms, and offers intriguing possibilities for unique reactivity and physical properties stemming from expected delocalization of the spin density over the NNN moiety and its conjugated substituents. Here, we report the synthesis and full characterization of the first NHC-stabilized triazenyl radicals, obtained by one-electron reduction of the corresponding triazenyl cations with potassium metal. These radicals reversibly oxidize back to the cations upon treatment with transition metal sources or electrophiles, and abstract H atom from xanthene to form a new N-H bond at the center nitrogen atom. Potential application of the redox couple between triazenyl cation and triazenyl radical was demonstrated as cathode active materials in lithium ion batteries.

We report a new approach to the synthesis of uniform, high areal density Pt nanocrystals supported by conducting polymers. The key strategy is the use of ice-templated, two-dimensional polyaniline nanosheets at the air-water interface as a platform for expediting Pt nucleation. Highly crystalline Pt nanoparticles with a narrow size distribution of 2.7 ± 0.3 nm and a high electrochemically active surface area of 94.57 m 2 g -1 were obtained. Pt NPs were strongly anchored to the polyaniline nanosheets, and demonstrated high current densities, good durability for the methanol oxidation reaction, and excellent carbon monoxide tolerance, all of which are unprecedented. The idea established in this study could be applied to the production of a wide range of other catalysts with enhanced activities.

We report a unique, highly conductive, dendrite-inhibited, solid-state polymer electrolyte platform that demonstrates excellent battery performance at subzero temperatures. A design based on functionalized inorganic nanoparticles with interconnected mesopores that contain surface nitrile groups is the key to this development. Solid-state hybrid polymer electrolytes based on succinonitrile (SN) electrolytes and porous nanoparticles were fabricated via a simple UV-curing process. SN electrolytes were effectively confined within the mesopores. This stimulated favorable interactions with lithium ions, reduced leakage of SN electrolytes over time, and improved mechanical strength of membranes. Inhibition of lithium dendrite growth and improved electrochemical stability up to 5.2 V were also demonstrated. The hybrid electrolytes exhibited high ionic conductivities of 2 × 10 -3 S cm -1 at room temperature and >10 -4 S cm -1 at subzero temperatures, leading to stable and improved battery performance at subzero temperatures. Li cells made with lithium titanate anodes exhibited stable discharge capacities of 151 mAh g -1 at temperatures below -10 °C. This corresponds to 92% of the capacity achieved at room temperature (164 mAh g -1 ). Our work represents a significant advance in solid-state polymer electrolyte technology and far exceeds the performance available with conventional polymeric battery separators.

Graphene quantum dot (GQD) layers were deposited as an energy-down-shift layer on crystalline-silicon solar cell surfaces by kinetic spraying of GQD suspensions. A supersonic air jet was used to accelerate the GQDs onto the surfaces. Here, we report the coating results on a silicon substrate and the GQDs' application as an energy-down-shift layer in crystalline-silicon solar cells, which enhanced the power conversion efficiency (PCE). GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density was enhanced by about 2.94% (0.9 mA/cm(2)) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

We have investigated a new methodology for improving the ionic conductivity and cation transport of polymer electrolytes by incorporating an anion-stabilizing hard polymer. A lamellar-forming poly(ethylene oxide- b -dithiooxamide) (PEO- b -PDTOA) block copolymer having enhanced ion conduction and mechanical strength, arising from PEO and PDTOA, respectively, was synthesized. Compared to a simple PEO/PDTOA blend, lithium salt-doped PEO- b -PDTOA exhibited significantly enhanced ionic conductivity, which is ascribed to efficient ion transport along the nanoscale PEO domains. Strikingly, by applying a dc polarization voltage, the inclusion of PDTOA afforded a high ratio of the steady state to the initial current flow of 0.67 for the PEO- b -PDTOA electrolytes, surpassing the value of 0.31 observed for conventional PEO-salt electrolytes. A key reason for achieving enhanced cation transport was the hydrogen bonding interactions between the thioamide moieties of PDTOA and the anions of lithium salts. This work provides fascinating experimental insights into the enhancement of cation transport of polymer electrolytes without chemically bonded negative charges and has implications for fast charging energy storage systems.

We developed a new ratiometric pH sensor based on poly(N-phenylmaleimide) (PPMI)-containing block copolymer that emits three different fluorescent colors depending on the pH. The strong solvatochromism and tautomerism of the PPMI derivatives enabled precise pH sensing for almost the entire range of the pH scale. Theoretical calculations have predicted largely dissimilar band gaps for the keto, enol, and enolate tautomers of PPMI owing to low-dimensional conjugation effects. The tunable emission wavelength and intensity of our sensors, as well as the reversible color switching with high-luminescent contrast, were achieved using rational molecular design of PPMI analogues as an innovative platform for accurate H(+) detection. The self-assembly of block copolymers on the nanometer length scale was particularly highlighted as a novel prospective means of regulating fluorescence properties while avoiding the self-quenching phenomenon, and this system can be used as a fast responsive pH sensor in versatile device forms.

The gas-phase oxygen-hydrogen exchange reaction dynamics of O((3)P) + i-C3H7 (isopropyl) → H((2)S) + CH3OCH3 (acetone) was first investigated by the vacuum-ultraviolet laser-induced fluorescence (VUV-LIF) spectroscopy in a crossed beam configuration. The nascent H-atom Doppler-profile analysis shows that the average translation energy of the products and the fraction of the total available energy released as the transitional energy were determined to be 33.3 ± 1.64 kcal mol(-1) and 0.38, respectively. With the aid of the CBS-QB3 level of ab initio theory and statistical calculations, it was found that the title reaction is one of the major reaction pathways and proceeds through the formation of dynamical, short-lived addition complexes. On the basis of a systematic comparison with several exchange reactions of hydrocarbon radicals, the large variation in the fractions of translational energy release can be understood in terms of the unique geometrical features of the transition states along the reaction coordinates on the doublet potential energy surfaces.

We have investigated a new means to control the morphology and conductivity of block copolymer electrolytes by the inclusion of ionic units at the chain ends. A set of poly(styrene- b -ethylene oxide) (PS-b-PEO) block copolymers having dissimilar PEO end groups (-OH, -SO 3 H, and -SO 3 Li) exhibited various self-assembled morphologies including disordered, lamellar, and hexagonal cylindrical phases. Strikingly, the addition of Li salts to PS-b-PEO with sulfonate terminal groups afforded enriched nanostructures with significant differences in their conductivities depending on the salt concentration. In particular, a gyroid morphology with a 2-fold-enhanced normalized ionic conductivity was found for the sulfonate-terminated PS-b-PEO when compared to disordered PS-b-PEO-OH. This is closely related to the structural advantages of gyroid having cocontinuous ionic channels, which enable efficient transport of Li + ions via less tortuous ion conduction pathways. This work presents fascinating experimental insights on the enhancement of ion transport efficiencies by modulating the self-assembly nature of polymer electrolytes by substituting with a single end-functional group.

Graphene quantum dots (GQDs) have been considered as a novel material because their electronic and optoelectronic properties can be tuned by controlling the size and the functional groups of GQDs. Here we report the synthesis of reduction-controlled GQDs and their application to bulk heterojunction (BHJ) solar cells with enhanced power conversion efficiency (PCE). Three different types of GQDs--graphene oxide quantum dots (GOQDs), 5 h reduced GQDs, and 10 h reduced GQDs--were tested in BHJ solar cells, and the results indicate that GQDs play an important role in increasing optical absorptivity and charge carrier extraction of the BHJ solar cells. The enhanced optical absorptivity by rich functional groups in GOQDs increases short-circuit current, while the improved conductivity of reduced GQDs leads to the increase of fill factors. Thus, the reduction level of GQDs needs to be intermediate to balance the absorptivity and conductivity. Indeed, the partially reduced GQDs yielded the outstandingly improved PCE of 7.60% in BHJ devices compared to a reference device without GQDs (6.70%).

We have developed a light-emitting material based on nonconjugated block copolymers that contain polystyrene sulfonate (PSS) chains. The confinement of the PSS chains within nanosized domains appeared to be a powerful means of achieving enhanced fluorescence signals. High fluorescence quantum yield, with a maximum value of 37%, was obtained by adjusting the types of self-assembled morphologies of PSS-containing block copolymers; in contrast, the fluorescence quantum yield was merely 5% for the PSS homopolymer lacking organization. The wavelength of fluorescence emission was tunable by rational molecular design. In addition, significant self-quenching behavior was not noticed in diverse forms of this material such as solutions, thin films, and free-standing membranes. Notably, the light-emitting self-assembled block copolymer electrolytes exhibited high sensitivity toward Cu(2+) ions, with a detection limit of parts per billion levels, rapid response time of ≤1 min, and insignificant interference of other competitive metal ions.

This paper presents a circulating tumor cell (CTC) microseparator for isolation of CTCs from human peripheral blood using immunomagnetic nanobeads with bound antiepithelial cell adhesive molecule (EpCAM) antibodies that specifically bind to epithelial cancer cells. The isolation is performed through lateral magnetophoresis, which is induced by high-gradient magnetic separation technology, involving a ferromagnetic wire array inlaid in the bottom substrate of a microchannel. Experimental results showed that the CTC microseparator isolates about 90% of spiked CTCs in human peripheral blood at a flow rate of up to 5 mL/h and purifies to approximately 97%. The overall isolation procedure was completed within 15 min for 200 μL of peripheral blood. CTCs from peripheral blood of patients with breast and lung cancers were isolated with the CTC microseparator, and the results were compared with those of healthy donors. Using a fluorescence-based viability assay, the viability of CTCs isolated from peripheral blood of patients with cancer was observed. In addition, the usefulness of the CTC microseparator for subsequent genetic assay was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR) amplification of cancer-specific genes using CTCs isolated from patients with cancer.

We have developed fast responsive, colorimetric and resistive-type polymeric humidity sensors from a series of self-assembled poly(styrenesulfonate-methylbutylene) (PSS-b-PMB) block copolymers with tailored hygroscopic properties. In dry state, the PSS-b-PMB films exhibit hexagonal cylindrical morphology where hydrophobic PMB cylinders are dispersed within a PSS matrix. Under levels of humidity, the PSS-b-PMB thin films self-displayed discernible reflective color changes, covering almost entire visible light regions from violet (RH = 20%) to red (RH = 95%). The sensors also revealed a few orders of magnitude changes in impedance with exposure to humid air by taking advantages of strong polymer electrolytes characteristics. Remarkably, the time to complete the changes in the signals was only a few seconds, as rationalized by good connectivity of the PSS domains and short water diffusion pathways in nanometer scales. Repeated hydration/dehydration tests demonstrated reliable sensor properties, which is in sharp contrast to the poor stability of PSS homopolymer sensors lacking organization.

Charge transfer in DNA is an essential process in biological systems because of its close relation to DNA damage and repair. DNA is also an important material used in nanotechnology for wiring and constructing various nanomaterials. Although hole transfer in DNA has been investigated by various researchers and the dynamic properties of this process have been well established, the dynamics of a negative charge, that is, excess electron, in DNA have not been revealed until now. In the present paper, we directly measured the rate of excess electron transfer (EET) through a consecutive thymine (T) sequence in nicked-dumbbell DNAs conjugated with a tetrathiophene derivative (4T) as an electron donor and diphenylacetylene (DPA) as an electron acceptor at both ends. The selective excitation of 4T by a femtosecond laser pulse caused the excess electron injection into DNA, and led to EET in DNA by a consecutive T-hopping mechanism, which eventually formed the DPA radical anion (DPA(•-)). The rate constant for the process of EET through consecutive T was determined to be (4.4 ± 0.3) × 10(10) s(-1) from an analysis of the kinetic traces of the ΔO.D. during the laser flash photolysis. It should be emphasized that the EET rate constant for T-hopping is faster than the rate constants for oxidative hole transfers in DNA (10(4) to 10(10) s(-1) for A- and G-hopping).

9-Substituted 6,6-dimethyl-11-oxo-6,11-dihydro-5H-benzo[b]carbazoles were discovered as highly selective and potent anaplastic lymphoma kinase (ALK) inhibitors by structure-based drug design. The high target selectivity was achieved by introducing a substituent close to the E(0) region of the ATP binding site, which has a unique amino acid sequence. Among the identified inhibitors, compound 13d showed highly selective and potent inhibitory activity against ALK with an IC(50) value of 2.9 nM and strong antiproliferative activity against KARPAS-299 with an IC(50) value of 12.8 nM. The compound also displayed significant antitumor efficacy in an established ALK fusion gene-positive anaplastic large-cell lymphoma (ALCL) xenograft model in mice without body weight loss.

We present an electric-field-triggered sphere-to-cylinder transition of negatively charged block copolymer micelles with a radically low electric field of 30 V/cm. The system investigated is dilute solutions of strong polyelectrolyte containing ionic-b-neutral block copolymers (i.e., poly(styrenesulfonate-b-methylbutylene)). We have carried out in situ small-angle X-ray scattering experiments equipped with a dc power supply, combined with electron microscopy and atomic force microscopy. The application of small electrical fields across the solutions of spherical micelles results in the transient morphology of interconnected spheres, which are eventually transformed into a cylindrical shape with time. The E-field-induced cylindrical micelles revert to spherical micelles when the E field is switched off.

We establish a new systematic methodology for controlling the water retention of polymer electrolyte membranes. Block copolymer membranes comprising hydrophilic phases with widths ranging from 2 to 5 nm become wetter as the temperature of the surrounding air is increased at constant relative humidity. The widths of the moist hydrophilic phases were measured by cryogenic electron microscopy experiments performed on humid membranes. Simple calculations suggest that capillary condensation is important at these length scales. The correlation between moisture content and proton conductivity of the membranes is demonstrated.

A nearly symmetric polystyrene-block-polyisoprene diblock copolymer dissolved at a concentration of 40% in styrene-selective solvents exhibited a cylinder-to-disorder transition upon heating. The solvents used were diethyl phthalate (DEP) and 75:25 and 50:50 mixtures of DEP with di-n-butyl phthalate (DBP). In DEP, the most styrene-selective of the three solvents, rheological measurements indicated a distinct plateau in the temperature-dependent elastic modulus across the 8 degrees C interval above the order-disorder transition temperature, T(ODT) = 116 degrees C. Previous small-angle neutron scattering measurements in this regime indicated the equilibrium phase to be a liquidlike solution of approximately spherical micelles. An isothermal frequency sweep in this regime indicated a very long relaxation time. Annealing eventually led to the recovery of liquidlike rheological response, over a time scale of hours. Qualitatively similar phenomena were also observed in 75:25 DEP/DBP and 50:50 DEP/DBP solutions, except the fact that the temperature window of the transient response is narrow and the time scale for the recovery diminishes significantly. Neither small-angle X-ray scattering nor static birefringence gave any clear signature of the transient structure. The structure that leads to the transient rheological response is attributed to micellar congestion due to the slow relaxation of anisotropic micelles into an equilibrium distribution of micelles. Possible origins of the remarkable solvent selectivity dependence are also discussed.

Steady-state fluorescence spectra were measured for 1,8-naphthahlimide-linker-phenothiazine dyads (NI-L-PTZ, where L = octamethylenyl ((CH2)8) and 3,6,9-trioxaundecyl ((CH2CH2O)3C2H4)), NI-C8-PTZ and NI-O-PTZ, as well as the NI derivatives substituted on the nitrogen atom with various linker groups without PTZ as the reference NI molecule in n-hexane. Normal fluorescence peaks were observed at 367-369 nm in all NI molecules together with a broader emission around 470 nm, which is assigned to the excimer emission between the NI in the singlet excited state (1NI*) and the NI moiety of another NI molecule (1[NI/NI]*). In addition, a broad peak around 600 nm was observed only for NI-L-PTZ, which is assigned to an intramolecular exciplex emission between donor (PTZ) and acceptor (NI) moieties in the excited singlet state, 1[NI-L-NI]*. The formation of an intramolecular exciplex corresponds to the existence of a conformer with a weak face-to-face interaction between the NI and PTZ moieties in the excited state because of the long and flexible linkers. The excited-state dynamics of the NI molecules in n-hexane were established by means of time-resolved fluorescence spectroscopy.

There is an intriguing, current controversy on the involvement of iron(III)-hydroperoxo species as a "second electrophilic oxidant" in oxygenation reactions by heme and non-heme iron enzymes and their model compounds. In the present work, we have performed reactivity studies of the iron-hydroperoxo species in nucleophilic and electrophilic reactions, with in situ-generated mononuclear non-heme iron(III)-hydroperoxo complexes that have been well characterized with various spectroscopic techniques. The intermediates did not show any reactivities in the nucleophilic (e.g., aldehyde deformylation) and electrophilic (e.g., oxidation of sulfide and olefin) reactions. These results demonstrate that non-heme iron(III)-hydroperoxo species are sluggish oxidants and that the oxidizing power of the intermediates cannot compete with that of high-valent iron(IV)-oxo complexes. We have also reported reactivities of mononuclear non-heme iron(III)-peroxo and iron(IV)-oxo complexes in the aldehyde deformylation and the oxidation of sulfides, respectively.

We investigate the effect of the casting solvent on the phase behavior of a cylinder-forming poly(styrene-b-isoprene) (PS-b-PI) diblock copolymer mixed with marginally selective gamma-Fe2O3 nanoparticles. Notably, for the mixtures of PS-b-PI/gamma-Fe2O3 nanoparticles cast with toluene, which is a neutral solvent for both PS and PI blocks, the latticelike aggregates of gamma-Fe2O3 nanoparticles, originating from magnetic dipole interactions, induce an intriguing transition from hexagonal cylinders to body-centered cubic spheres via undulated cylinders whereas the neat block copolymer does not show such an order-order transition. In contrast, when PI-selective hexane is used, the nanoparticles are selectively incorporated into the PI domains, and the microphase-separated hexagonal cylinder morphology gradually loses its long-range order upon increasing the nanoparticle concentration. The structural information obtained from small-angle X-ray scattering is also in good agreement with transmission electron microscopy images and differential scanning calorimetry results.

Axial ligand substitution of a mononuclear nonheme oxoiron(IV) complex, [FeIV(O)(TMC)(NCCH3)]2+ (1) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), leads to the formation of new FeIV=O species with relatively intense electronic absorption features in the near-UV region. The presence of these near-UV features allowed us to make the first observation of Fe=O vibrations of S = 1 mononuclear nonheme oxoiron(IV) complexes by resonance Raman spectroscopy. We have also demonstrated that the reactivity of nonheme oxoiron(IV) intermediates is markedly influenced by the axial ligands.

The phase behavior of a symmetric styrene-isoprene (SI) diblock copolymer in a styrene-selective solvent, diethylphthalate, was investigated by in situ small-angle X-ray scattering on isotropic and shear-oriented solutions and by rheology and birefringence. A remarkable new feature in this phase diagram is the coexistence of both body-centered cubic (bcc) and hexagonally close-packed (hcp) sphere phases, in a region between close-packed spheres (cps) and hexagonally packed cylinders (hex) over the concentration range phi approximately 0.33-0.45. By focusing on the transitions among these various ordered phases during heating and cooling cycles, we observed a strong hysteresis: supercooled cylinders persisted upon cooling. The stability of these supercooled cylinders is quite dependent on concentration, and for phi > or = 0.40, the supercooled cylinders do not revert to spheres even after quiescent annealing for 1 month. The spontaneous formation of spheres due to the dissociation of cylinders is kinetically hindered in this case, and the system is apparently not amenable to any pretransitional fluctuations of cylinders prior to the cylinder-to-sphere transition. This contrasts with the case of cylinders transforming to spheres upon heating in the melt. The application of large amplitude shear to the supercooled cylinders is effective in restoring the equilibrium sphere phases.

The gelation behavior of aqueous solutions of poly(ethylene oxide-b-(DL-lactic acid-co-glycolic acid)-b-ethylene oxide) (PEO-PLGA-PEO) triblock copolymer containing short hydrophilic PEO end blocks is investigated using dynamic light scattering, rheology, small-angle neutron scattering (SANS), and differential scanning calorimetry (DSC). For polymer concentrations between 5 and 35 wt %, four distinct regions of the turbidity change depending on temperature were observed. Interestingly, in the turbid solution region, gel phase is formed for polymer concentrations above 14 wt % and an extremely slow relaxation was detected. In fact, a power law, which takes into account the dynamics of percolation clusters, dominates the correlation function. In rheological measurements, the local maximum in G' is observed at around the temperature of maximum turbidity. We further found that G" > G' and G' is highly dependent on frequency at the gel state implying viscoelastic characteristics, which is quite different from general concepts of gels, typically formed by the micellar packing. SANS profiles showing multiple peaks in the sol state rather than in the gel state as well as a DSC exotherm at the temperature of gels can also serve as the evidence of different gel states. Based upon the experimental data obtained in the present study, a new gelation mechanism induced by the macroscopic phase separation of triblock copolymers containing short hydrophilic PEO end blocks such as PEO-PLGA-PEO is proposed. The effect of the type ofhydrophobic middle blocks on the gelation is also discussed.