Formation of helical J-aggregate of chiral thioether-derivatized phthalocyanine bound by palladium(II) at the toluene/water interface

A chiral thioether-substituted phthalocyanine ((2,3,9,10,16,17,23,24-octakis-1-phenylethylthiophthalocyaninato)magnesium(II) [MgPc(SEtPh)8]) has been synthesized, which can be bound by soft-metal ions such as palladium(II) ion. Aggregates formed from MgPc(SEtPh)8 and Pd(II) in toluene and at the toluene/water interface were characterized by means of UV-vis absorption and circular dichroism (CD) spectrometries using centrifugal liquid-membrane (CLM) cell. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) and scanning electron microscope (SEM) were used as complementary techniques. The toluene solution of MgPc(SEtPh)8 had no optical chirality. However, the addition of PdCl2 into the toluene solution of MgPc(SEtPh)8 induced optical chirality, which indicated the formation of a twisted H-type dimer (face-to-face fashion) of MgPc(SEtPh)8 bound by four PdCl2 in the bulk toluene solution. On the other hand, in the toluene/water interface, helical J-aggregate (head-to-tail fashion) of MgPc(SEtPh)8 bound by PdCl2 was formed, in which one J-aggregate unit contained five 1:2 complexes of MgPc(SEtPh)8-Pd(II) on average. On the basis of the experimental results and the exciton theory for optical chirality, a possible mechanism for the chiral aggregation of MgPc(SEtPh)8-Pd(II) complexes at the interface was proposed. In the present study, we demonstrated a novel strategy for the design of helical phthalocyanine aggregates using the liquid/liquid interface as a template.     

Development of a quasi-phase-matched, second-harmonic generation periodically poled lithium niobate waveguide with an integrated electro-optical modulator

A novel type of waveguide quasi-phase-matched device with output electro-optical (EO) modulation is proposed and demonstrated. The second-harmonic generated output can be modulated with a high extinction ratio by integration of dual EO phase modulators on a periodically poled lithium niobate waveguide. Blue and green coherent light with EO modulation was demonstrated, and wavelength dispersion of r33 is discussed.     

Rainbow Generalizations of Ramsey Theory: A Survey

In this work, we collect Ramsey-type results concerning rainbow edge colorings of graphs.     

High‐Pressure Synthesis of A2NiO2Ag2Se2 (A=Sr,Ba) with a High‐Spin Ni2+ in Square‐Planar Coordination

Square‐planar coordinate Ni²⁺ ions in oxides are exclusively limited to a low‐spin state (S=0) owing to extensive crystal field splitting. Layered oxychalcogenides A₂Ni^IIO₂Ag₂Se₂ (A=Sr, Ba) with the S=1 NiO₂ square lattice are now reported. The structural analysis revealed that the Ni²⁺ ion is under‐bonded by a significant tensile strain from neighboring Ag₂Se₂ layers, leading to the reduction in crystal field splitting. Ba₂NiO₂Ag₂Se₂ exhibits a G‐type spin order at 130 K, indicating fairly strong in‐plane interactions. The high‐pressure synthesis employed here possibly assists the expansion of NiO₂ square lattice by taking the advantage of the difference in compressibility in oxide and selenide layers.     

Data‐Driven Materials Exploration for Li‐Ion Conductive Ceramics by Exhaustive and Informatics‐Aided Computations

Interest in all‐solid‐state Li‐ion batteries (LIBs) using non‐flammable Li‐conducting ceramics as solid electrolytes has increased, as safe and robust batteries are urgently desired as power sources for (hybrid) electric vehicles. However, the low Li‐ion conductivities of ceramics have hindered all‐solid‐state LIB commercialization; many researchers have attempted to develop fast Li‐ion conductors. We introduce two efficient high‐throughput computational approaches for materials exploration: (i) exhaustive search and (ii) informatics‐aided prediction. For demonstration, ～400 Li‐ and Zn‐containing oxide (Li?Zn?X?O) compounds of varied crystal structures are extracted from Materials Project datasets. We calculate the migration energies for Li‐ion conduction and the phase stabilities (decomposition energies) of these materials by simulation and apply Bayesian optimization to determine the material with the highest ionic conductivity. The results show much greater efficiency than a random search algorithm.     

Design of Thermochromic Luminescent Dyes Based on the Bis(ortho‐carborane)‐Substituted Benzobithiophene Structure

To obtain solid‐state emissive materials having stimuli‐responsive luminescent chromic properties without phase transition, benzobithiophenes modified with two o‐carborane units having various substituents in the adjacent phenyl ring in o‐carborane were designed and synthesized. Their emission colors were strongly affected not only by the substituents at the para‐position of the phenyl ring but also by molecular distribution in the solid state. In particular, the emission colors were changed by heating without crystal phase transition. It was proposed that their thermochromic properties were correlated not with isomerization but with the molecular motion at the distorted benzobithiophene moiety.     

Low-frequency surface-enhanced Raman scattering spectroscopy at metal electrode surfaces

Low-frequency surface-enhanced Raman scattering (SERS) spectroscopy is a versatile tool for studying surface phenomena under electrochemical conditions. This spectroscopy enables us to obtain rich information on extramolecular vibrations between substrate and adsorbates, which are sensitive to atomistic surface features of the substrate. Owing to recent advancements in optical filter technology, low-frequency SERS signals are now becoming easily detectable using conventional Raman systems equipped with holographic notch filters. In addition, SERS background signals, which have been simply ignored, can provide electronic information on the metal substrate. This allows us to observe both sides of electrode–electrolyte interfaces in situ and simultaneously, which is never expected in far-infrared or terahertz absorption spectroscopy. This advanced SERS spectroscopy can help our understanding of electrochemical and electrocatalytic reactions at the molecular scale.     

Consideration of Molecular Structure in the Excited State to Design New Luminogens with Aggregation‐Induced Emission

Aggregation‐induced emission (AIE) is a photoluminescence phenomenon in which an AIE luminogen (AIEgen) exhibits intense emission in the aggregated or solid state but only weak or no emission in the solution state. Understanding the mechanism of AIE requires consideration of excited state molecular geometry (for example, a π twist). This Minireview examines the history of AIEgens with a focus on the representative AIEgen, tetraphenylethylene (TPE). The mechanisms of solution‐state quenching are reviewed and the crucial role of excited‐state molecular transformations for AIE is discussed. Finally, recent progress in understanding the relationship between excited state molecular transformations and AIE is overviewed for a range of different AIEgens.     

Phenomenological aspects of possible vacua of a neutrino flavor model

We discuss a supersymmetric model with discrete flavor symmetry A_4×Z_3. The additional scalar fields which contribute masses of leptons in the Yukawa terms are introduced in this model. We analyze their scalar potential and find that they have various vacuum structures. We show the relations among 24 different vacua and classify them into two types. We derive expressions of the lepton mixing angles, Dirac CP violating phase and Majorana phases for the two types. The model parameters which are allowed by the experimental data of the lepton mixing angles are different for each type. We also study the constraints on the model parameters which are related to Majorana phases. The different allowed regions of the model parameters for the two types are shown numerically for a given region of two combinations of the CP violating phases.     

Development of spin-coated Si/TiOx/Pt/TiOx electrodes for the electrochemical ozone production

A novel electrode having the compositional sequence Si/TiOx/Pt/TiOx was developed for ozone electrogeneration. The spin-coating method, the sputtering deposition technique, and a post-annealing procedure were all combined to assemble the electrode composition. A two-compartment electrolytic cell separated by a Nafion membrane was used to generate ozone galvanostatically. The X-ray photon electron spectroscopy (XPS) and atomic force microscopy (AFM) were used to reveal the electrode composition and morphology. The influence of several factors including the electrode's annealing temperature, the electrolyte composition, and the electrolysis’ current density on the efficiency of ozone production was investigated. A maximum ozone generation efficiency of 2.5% was obtained at 74 mA cm⁻² at room temperature. Interestingly, the electrode preserved (ca. 80%) of its original activity to produce ozone after 50 h of continues electrolysis at 74 mA cm⁻² at room temperature.