Emission mechanism of radiophotoluminescence in Ag-doped phosphate glass

The objective of this study is to investigate the emission mechanism of radiophotoluminescence (RPL) in the Ag⁺-doped phosphate glass (glass dosimeter), which is now used as individual radiation dosimeter, because the emission mechanism of RPL in glass dosimeter was not fully understood. Optical properties such as optical absorption spectrum, RPL spectrum and change of RPL spectrum as a function of X-ray irradiation dose were measured for commercially available glass dosimeter. In this study, we discuss the emission mechanism of two RPL peaks at 460 nm and 560 nm, based on the fact that electrons and holes produced by X-ray irradiation are trapped at Ag⁺ ions to produce Ag⁰ and Ag²⁺ ions, respectively, when the Ag⁺-doped phosphate glass is exposed to X-ray. We would like to propose the emission mechanism of RPL peaks at 460 nm and 560 nm, concerning with Ag²⁺ and Ag⁰ ions.     

Synthesis of optically active conjugated polymers containing platinum in the main chain: Control of the higher‐order structures by substituents and solvents

The Sonogashira–Hagihara coupling polymerization of d ‐hydroxyphenylglycine‐derived diiodo monomers 1–4 and platinum‐containing diethynyl monomer 5 gave the corresponding polymers [poly( 1–5 )–( 2–5 )] with number‐average molecular weights of 19,000–25,000 quantitatively. The polymers were soluble in CHCl₃, CH₂Cl₂, THF, and DMF. CD and UV–vis spectroscopic analysis revealed that amide‐substituted polymers [poly( 1–5 ) and poly( 2–5 )] formed chiral higher‐order structures in solution, while ester‐substituted polymers [poly( 3–5 ) and poly( 4–5 )] did not. Poly( 1–5 ) formed one‐handed helices in THF/toluene mixtures, while it formed chiral aggregates in THF/MeOH mixtures. Poly( 1–5 ) emitted fluorescence with quantum yields ranging from 0.8 to 1.3%. The polymers usually aggregated in the solid state. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2452–2461     

The reHISS Three-Range Exchange Functional with an Optimal Variation of Hartree–Fock and Its Use in the reHISSB-D Density Functional Theory Method

In the present study, we have reparametrized the HISS exchange functional. The new “reHISS” exchange provides a balance between short- and mid-range Hartree–Fock exchange (HFX) and a large total HFX coverage, with a fast convergence to zero HFX in the long range. The five parameters in this functional (according to equations 3 and 4 in the main text) are c_SR = 0.15, c_MR = 2.5279, c_LR = 0, ω_SR = 0.27, and ω_LR = 0.2192. The combination of reHISS exchange with a reparametrized B97c-type correlation functional (Chan et al., J. Comput. Chem. 2017 , 38, 2307) and a D2 dispersion term (s₆ = 0.6) gives the reHISSB-D method. We find it to be more accurate than related screened-exchange methods and, importantly, its accuracy is more uniform across different properties. Fundamentally, our analysis suggests that the good performance of the reHISS exchange is related to it capturing a near-optimal proportion of HFX in the range of interelectronic distance that is important for many chemical properties, and we propose this range to be approximately 1–4Å. © 2018 Wiley Periodicals, Inc.     

Synthesis,Electronic, and Morphological Properties of Tetrahedral Oligothiophenes with n‐Hexyl Terminal Groups

A series of tetrahedral oligothiophenes bearing n‐hexyl groups at the α‐positions of the terminal thiophene rings, (n‐C₆H₁₃(C₄H₂S)_n)₄C (Hex‐TnTM; n=1–4), has been synthesized by Kosugi–Migita–Stille coupling as a key reaction. Thanks to the improved solubility afforded by the terminal n‐hexyl groups, the largest homologue (n=4) was successfully obtained. Whereas the smaller derivatives (n=1, 2) were obtained as liquid substances, the larger derivatives (n=3, 4) were obtained as solids. Hex‐T3 TM partially adopts syn conformations between the adjacent thiophene rings in the crystal, probably owing to the packing force. Hex‐T3 TM not only appeared in the crystalline state but also the amorphous state, which was stable to up to 80 °C. Regardless of the terminal groups, the derivatives of n=2 exhibited a broad fluorescence with large Stokes shifts compared to the corresponding linear analogues, thereby suggesting the presence of intramolecular interactions between the bithiophene moieties. Interactions between terthiophene branches was also suggested in the radical cations of Hex‐T3 TM by cyclic voltammetry measurements.     

Performance assessment of a new laser system for efficient spin exchange optical pumping in a spin maser measurement of <Superscript>129</Superscript>Xe EDM

We demonstrate spin-exchange optical pumping of ¹²⁹Xe atoms with our newly made laser system. The new laser system was prepared to provide higher laser power required for the stable operation of spin maser oscillations in the ¹²⁹Xe EDM experiment. We studied the optimum cell temperature and pumping laser power to improve the degree of ¹²⁹Xe spin polarization. The best performance was achieved at the cell temperature of 100 ^°C with the presently available laser power of 1 W. The results show that a more intense laser is required for further improvement of the spin polarization at higher cell temperatures in our experiment.     

para‐Phenylene‐Bridged Spirobi(triarylamine) Dimer with Four Perpendicularly Linked Redox‐Active π Systems

para‐Phenylene‐bridged spirobi(triarylamine) dimer 2 , in which π conjugation through four redox‐active triarylamine subunits is partially segregated by the unique perpendicular conformation, was prepared and characterized by structural, electrochemical, and spectroscopic methods. Quantum chemical calculations (DFT and CASSCF) predicted that the frontier molecular orbitals of 2 are virtually fourfold degenerate, so that the oxidized states of 2 can give intriguing electronic and magnetic properties. In fact, the continuous‐wave ESR spectroscopy of radical cation 2 ^.+ showed that the unpaired electron was trapped in the inner two redox‐active dianisylamine subunits, and moreover was fully delocalized over them. Magnetic susceptibility measurements and pulsed ESR spectroscopy of the isolated salts of 2 , which can be prepared by treatment with SbCl₅, revealed that the generated tetracation 2 ⁴⁺ decomposed mainly into a mixture of 1) a decomposed tetra(radical cation) consisting of a tri(radical cation) moiety and a trianisylamine radical cation moiety (≈75 %) and 2) a diamagnetic quinoid dication in a tetraanisyl‐p‐phenylendiamine moiety and two trianisylamine radical cation moieties (≈25 %). Furthermore, the spin‐quartet state of the tri(radical cation) moiety in the decomposed tetra(radical cation) was found to be in the ground state lying 30 cal mol^?1 below the competing spin‐doublet state.     

Combining Living Anionic Polymerization with Branching Reactions in an Iterative Fashion to Design Branched Polymers

This paper reviews the precise synthesis of many‐armed and multi‐compositional star‐branched polymers, exact graft (co)polymers, and structurally well‐defined dendrimer‐like star‐branched polymers, which are synthetically difficult, by a commonly‐featured iterative methodology combining living anionic polymerization with branched reactions to design branched polymers. The methodology basically involves only two synthetic steps; (a) preparation of a polymeric building block corresponding to each branched polymer and (b) connection of the resulting building unit to another unit. The synthetic steps were repeated in a stepwise fashion several times to successively synthesize a series of well‐defined target branched polymers.

     

Oxovanadium(v)-catalyzed oxidative biaryl synthesis from organoborate under O2

Oxidative ligand coupling of organoborates was catalyzed by VO(OEt)Cl(2) under oxygen atmosphere, which provides a versatile method for the selective synthesis of symmetrical or unsymmetrical biaryls.