Electrofluorochromism based on the valence change of europium complexes in electrochemical devices with Prussian blue as the counter electrode.

The electrofluorochromism of Eu complexes based on the valence change between Eu and Eu is demonstrated in a two-electrode electrochemical device consisting of Prussian blue (PB) as the counter electrode. This study aims to improve the electrofluorochromic (EFC) performance of luminescence switching between Eu and Eu by enhancing the electrochemical reactivity of the EFC device. By introducing a PB film as a counter electrode in a two-electrode device, the redox reaction of Eu is promoted because of charge compensation by the counter PB film.

Silver to Gold Metallic Luster Changes in Stimuli-Responsive Diacetylene Derivatives Uniquely Arranged within Crystals.

Eye-catching metallic luster materials, especially those whose colors can be controlled by external stimuli, have many potential applications. Here, we present a silver luster material that changes color to gold upon UV irradiation. Diacetylene (DA) derivatives with stilbenes introduced via linkers at both ends ( ( = 1-6)) exhibited significantly different metallic luster and color change behaviors depending on the linker carbon number ().

The effect of a polymer capping agent on electrodeposited silver nanoparticles in a silver deposition-based electrochromic device.

In this study, polyvinylpyrrolidone (PVP) was introduced into an Ag deposition-based electrochromic (EC) device as a capping agent for electrodeposited Ag nanoparticles (AgNPs) to improve the coloration characteristics of EC devices and to precisely control the size and shape of the AgNPs. Through the coordination of PVP molecules with Ag ions in the EC electrolyte, the critical voltage for the deposition of AgNPs decreased, resulting in a lower operating voltage of the EC device in comparison with the conventional one. Because particle growth and AgNP aggregation were suppressed by the capping effect of PVP, uniform electrodeposition of AgNPs was achieved.

Electrochemically regulated luminescence of europium complexes with β-diketone in polyether matrices.

This study investigates the electrochemical modulation of luminescence color, , electrofluorochromism, of an Eu complex in a polyether solvent. The electrofluorochromic (EFC) reaction of the Eu complex occurred a reversible redox reaction between Eu and Eu. Initially, the intrinsically stable Eu complex showed intense red photoluminescence (PL) induced by f-f transitions.

Magenta-Blue Electrofluorochromic Device Incorporating Eu(III) Complex, Anthracene Derivative, and Viologen Molecule.

Electrochemical switching of luminescence color between magenta and blue using two types of luminescent materials and electrochromic molecules was demonstrated based on the control of excited energy transfer through an electrochromic reaction. The magenta photoluminescence, due to the integration of red luminescence from the Eu(III) complex and blue fluorescence from the anthracene derivative, was reversibly modulated to a pure-blue luminescence color by an electrochemical redox reaction. Electrofluorochromism is induced by effective excited energy transfer from the Eu(III) complex to the electrochromic molecule under a redox reaction.

Anion-Dependent Outstanding Luminescence Enhancement of Eu(D-facam) Upon Coexistence With the Tetramethylammonium Cation.

The front cover artwork is provided by the group of Norihisa Kobayashi and Kazuki Nakamura at Chiba University. The image shows the drastic luminescence enhancement and induced circular polarization of Eu(D-facam) in the presence of tetramethylammonium acetate. Read the full text of the Article at 10.

Anion-Dependent Outstanding Luminescence Enhancement of Eu(D-facam) Upon Coexistence With the Tetramethylammonium Cation.

The effect of a series of tetramethylammonium salts with different counter anions on the photophysical properties of a chiral Eu(III) complex (Eu(D-facam) ) was investigated. Anion-dependent luminescence of the Eu(III) complex was observed, and particularly in the presence of acetate ions, an outstanding luminescence enhancement (>300 times) and induced circularly polarized luminescence (g =-0.63) were obtained.

Chiroptical property enhancement of chiral Eu(III) complex upon association with DNA-CTMA.

DNA-based materials have attracted much attention due to their unique photo-functional properties and potential applications in various fields such as luminescent and biological systems, nanodevices, etc. In this study, the photophysical properties of a chiral Eu(III) complex, namely (Eu(D-facam)), within DNA films were extensively investigated. The enhancement of photoluminescence (more than 25-folds increase of luminescence quantum yield) and degree of circularly polarization in luminescence (g = - 0.

An improvement in the coloration properties of Ag deposition-based plasmonic EC devices by precise control of shape and density of deposited Ag nanoparticles.

Ag nanoparticles exhibit various colors depending on their localized surface plasmon resonance (LSPR). Based on this phenomenon, Ag deposition-based electrochromic devices can represent various optical states in a single device such as the three primary colors (cyan, magenta, and yellow), silver mirror, black and transparent. A control of the morphology of Ag nanoparticles can lead to dramatic changes in color, as their size and shape influence the LSPR band.

Alkyl ammonium ion-induced drastic emission enhancement of Eu(D-facam) in 1-butanol.

Drastic enhancements in both emission intensity and circular polarization of a Eu(iii) complex were achieved in 1-butanol solution in the presence of alkylammonium ions.

Thermosalience in Macrocycle-Based Soft Crystals via Anisotropic Deformation of Disilanyl Architecture.

We describe here the preparation of soft crystals using disilanyl macrocycle possessing four -phenylenes circularly connected by four flexible disilane bonds. Single crystals of exhibited a reversible thermal single-crystal-to-single-crystal (SCSC) phase transition behavior between two crystal phases accompanied by remarkable mechanical motion (thermosalient effect), as revealed by thermal analyses and X-ray diffraction measurements. Detailed structural analyses implied that flexibility of the parallelogram disilanyl architecture and molecular packing mode via weak intermolecular interactions facilitated a concerted structural transformation (parallel crank motion) of macrocycles in the crystal, thus resulting in the SCSC phase transition accompanied by anisotropic shrinking/elongation of the cells to induce the thermosalient effect.

Non-Volatile Transistor Memory with a Polypeptide Dielectric.

Organic nonvolatile transistor memory with synthetic polypeptide derivatives as dielectric was fabricated by a solution process. When only poly (γ-benzyl-l-glutamate) (PBLG) was used as dielectric, the device did not show obvious hysteresis in transfer curves. However, PBLG blended with PMMA led to a remarkable increase in memory window up to 20 V.

Electrochemically triggered upconverted luminescence for light-emitting devices.

Electrochemically triggered upconverted luminescence through triplet-triplet energy transfer (TTET) and subsequent triplet-triplet annihilation upconversion (TTA-UC) is observed for the first time in the electrochemiluminescence properties of a Ru(bpy)32+/DPA-containing electrochemical device.

A novel organic electrochromic device with hybrid capacitor architecture towards multicolour representation.

Despite the application of electrochromic (EC) technologies in various optical modulating devices, the challenge to achieve multicolour EC behavior in a single device still remains. However, because almost all EC materials exhibit a single colour change, only a few organic materials are able to undergo multiple colour switching within a single device. The development of multicolour EC applications is therefore highly limited.

Ultrafast Response in AC-Driven Electrochemiluminescent Cell Using Electrochemically Active DNA/Ru(bpy) Hybrid Film with Mesoscopic Structures.

Electrochemiluminescence (ECL) refers to light emission induced by an electrochemical redox reaction. The stability, emission response, and light intensity of the ECL device are known to be improved by using an alternating current (AC) voltage. In this paper, an AC-driven ECL device is fabricated with DNA/Ru(bpy) hybrid film-modified electrode.

Red luminescence control of Eu(iii) complexes by utilizing the multi-colored electrochromism of viologen derivatives.

The electroresponsive switching of red photoluminescence based on the electrochemical coloration of cyan-magenta-green (CMG) viologen components was achieved by combining a luminescent Eu chelate and viologen derivatives, resulting in CMG coloration in a single cell. The cell coloration was controlled by an electrochromic (EC) reaction, which also modulated the photoluminescence of the Eu chelate with high contrast, by transferring energy from the excited state of the Eu ion to the colored states of EC molecules. Cyclic voltammograms, photoluminescence spectra, absorption spectra, luminescence quantum yields, and luminescence lifetimes were measured to clarify the differences between the luminescence quenching and energy transfer efficiencies for each C, M, and G coloration associated with the electrochromism.

Why were alternating-current-driven electrochemiluminescence properties from Ru(bpy)3(2+) dramatically improved by the addition of titanium dioxide nanoparticles?

Electrochemiluminescence (ECL) is a phenomenon in which light is emitted from the excited state of a redox-active material generated by electrochemical reactions. Among light-emitting devices, ECL devices have various advantages in terms of structure and ease of fabrication, and therefore, they are expected to be next-generation emitting devices. In this study, we introduced rutile-type titanium dioxide nanoparticles (TiO2 NPs) in a Ru(ii)-complex-based electrolyte to improve the emission properties of an alternating current (AC)-driven ECL device.

High-contrast electroswitching of emission and coloration based on single-molecular fluoran derivatives.

Multifunctional electroswitching of both emission and coloration was demonstrated by using fluoran derivatives in an electrolytic solution. Further, in order to investigate changes in the photophysical properties induced by electrical stimuli, we measured cyclic voltammogram, absorption spetra, emission spectra, and molecular orbital calculation. The mechanism for this electroswitching was attributed to the reversible electrochemically induced closing and opening of the lactone ring in the fluoran molecule.

A localized surface plasmon resonance-based multicolor electrochromic device with electrochemically size-controlled silver nanoparticles.

The first localized surface plasmon resonance (LSPR)-based multicolor electrochromic device with five reversible optical states is demonstrated. In this device, the size of deposited silver nanoparticles is electrochemically controlled by using a voltage-step method in which two different voltages are applied successively. The electrochemically size-controlled silver nanoparticles enable a reversible multiple-color change by a shift of the LSPR band.

Electroswitching of emission and coloration with quick response and high reversibility in an electrochemical cell.

No fade to grey: Electroswitching of emission and coloration was achieved for a combination of a luminescent Eu(III) complex and an electrochromic molecule of diheptyl viologen (HV(2+)), indicating that such a combination could be used as a display material with dual emissive and reflective modes. The Prussian blue (PB)-modified electrode improved the response time and reversibility for the switching of emission and coloration, by acting as a counter electrode for the electrochromism of HV(2+).

Improvement in reflective-emissive dual-mode properties of electrochemical displays by electrode modification.

We studied the electrochromic (EC) and electrochemiluminescent (ECL) properties of a novel dual-mode display (DMD) cell that was enabled for reflective and emissive modes of representation by introducing both EC and ECL materials into an electrochemical cell. We fabricated EC, ECL, and DMD cells based on a simple-mixture solution or modified electrodes and compared their properties to clarify the advantage of a DMD system based on modified electrodes. Both the solution- and modified electrode-based DMDs showed EC properties in the reflective mode under dc bias application and ECL properties in the emissive mode under ac bias application.

Electrochemically controllable emission and coloration by using europium(III) complex and viologen derivatives.

We have demonstrated electroswitchable emission and coloration using a novel composite material containing luminescent europium(III) complex Eu(hfa)(3)(H(2)O)(2) and diheptyl viologen HV(2+). The photoluminescence of the Eu(III) complex was controlled by the electrochemical coloration of HV(2+)via intermolecular energy transfer mechanisms.

Multicolored electrochromism in 4,4'-biphenyl dicarboxylic acid diethyl ester.

We investigated the properties of 4,4'-biphenyl dicarboxylic acid diethyl ester (PCE). The PCE underwent a 2-step reduction at -1.5 V and -2.