Synthesis and characterization of new linear pi-conjugated molecules containing bis(ethynylpyridine) units with a benzothiadiazole spacer

Three novel 4,7-bis(n-pyridylethynyl)-2,1,3-benzothiadiazoles (n = 2, 3, and 4) were synthesized by using the Sonogashira cross-coupling reaction of 4,7-dibromo-2,1,3-benzothiadiazole with the corresponding ethynylpyridines in the presence of a Pd(II) catalyst. The viologen analogues were also prepared by methylation of pyridyl nitrogen atoms. X-ray structure analysis of these compounds revealed the linear molecular structures with unusual columnar crystal structures. Insertion of a benzothiadiazole moiety into the acetylene-pyridine skeleton brings about a large increase in electron affinity and the bispyridyl compounds obtained here show high fluorescence quantum yields.     

Applying a new method for analyzing experimental data on nuclear reactions at high energies

A new statistical method is proposed for the analysis of experimental data obtained in nucleus-nucleus collisions at high energies which borrows from ideas developed using the Random Matrix Theory. The method allows us to detect regions with correlation effects in the momentum distributions of secondary particles.     

Independent isomeric yield ratios of 95m,gNb in the natMo(γ, pxn) and natZr(p,xn) reactions

The independent isomeric yield ratios of ^95m,gNb from the ^natMo(γ, pxn) reactions with bremsstrahlung end-point energies of 45, 50, 55, 60, and 70 MeV were determined by an activation and an off-line γ-ray spectrometric technique at the Pohang accelerator laboratory (PAL), Korea. The isomeric yield ratios of ^95m,gNb from the ^natZr(p, xn) reactions were also determined in eight different proton energies within 19.4–44.7 MeV by a stacked-foil activation and an off-line γ-ray spectrometric technique using the MC-50 cyclotron of Korea Institute of Radiological and Medical Sciences (KIRAMS), Korea. The measured isomeric yield ratios of ^95m,gNb from the present work and the literature data in the ^natMo(γ, pxn) and ^natZr(p, xn) reactions were compared with the similar literature data in the ^natMo(p, αxn) reactions. It was found that the isomeric yield ratio of ^95m,gNb increases with projectile energy, which indicate the effect of excitation energy. However, at the same excitation energy, the isomeric yield ratios of ^95m,gNb in the ^natZr(p, xn) and ^natMo(p, αxn) reactions are higher than those in the ^natMo(γ, pxn) reaction, which indicates the role of input angular momentum. The isomeric yield ratios of ^95m,gNb in the ^natMo(γ, pxn), ^natZr(p, xn), and ^natMo(p, αxn) reactions were also calculated using computer code TALYS 1.4. The calculated isomeric yield ratios of ^95m,gNb from three reactions increase with excitation energy. However, in all the three reactions, the calculated values are significantly higher than the experimental data.     

Field due to a point source in a layer over an inhomogenous medium

Summary A point source at an interface between a homogeneous layer of finite depth and an inhomogeneous half-space is considered. The transmitted wave and the dispersion relation for the Love waves is calculated analytically. The authors of this paper have agreed to not receive the proofs for correction.     

Extractives of Milletia auriculata—III

Two new pyranoisoflavones, auriculasin and isoauriculasin were isolated from M. auriculata and assigned structures 1 and 3 respectively. The structure assigned earlier to isoauriculatin has been revised to 4.     

Adsorption behaviour of some metal ions and their oxinates on Zeokarb-226

Summary To develop a preconcentration technique for trace elements in aqueous solution, the adsorption behaviour of some metal ions and their oxinates on a weak carboxylic acid resin (Zeokarb-226) in the H⁺ form was investigated. Results indicate that under the conditions of the experiment, the resin behaves like a chelating ion-exchanger and that by selecting appropriate conditions, a group of ions such as U(VI), Th(IV), Pb(II), Hg(II), Fe(III) may be separated from many other ions.

---

Adsorptionsverhalten einiger Metallionen und ihrer Oxinate an Zeokarb-226

Zusammenfassung Das Adsorptionsverhalten einiger Metallionen und ihrer Oxinate an dem schwachen Carbonsäureharz Zeokarb-226 (H⁺-Form) wurde untersucht, um ein Anreicherungsverfahren für Spurenelemente in wäßriger Lösung zu entwickeln. Die Ergebnisse zeigen, daß sich das Harz unter den gegebenen Bedingungen als Chelataustauscher verhält und geeignet ist für die selektive Anreicherung von z.B. U(VI), Th(IV), Pb(II), Hg(II) und Fe(III).

     

Selective CO2 Reduction to Ethylene Mediated by Adaptive Small-molecule Engineering of Copper-based Electrocatalysts

Electrochemical CO₂ reduction reaction (CO₂RR) over Cu catalysts exhibits enormous potential for efficiently converting CO₂ to ethylene (C₂H₄). However, achieving high C₂H₄ selectivity remains a considerable challenge due to the propensity of Cu catalysts to undergo structural reconstruction during CO₂RR. Herein, we report an in situ molecule modification strategy that involves tannic acid (TA) molecules adaptive regulating the reconstruction of a Cu-based material to a pathway that facilitates CO₂ reduction to C₂H₄ products. An excellent Faraday efficiency (FE) of 63.6 % on C₂H₄ with a current density of 497.2 mA cm⁻² in flow cell was achieved, about 6.5 times higher than the pristine Cu catalyst which mainly produce CH₄. The in situ X-ray absorption spectroscopy and Raman studies reveal that the hydroxyl group in TA stabilizes Cu^δ+ during the CO₂RR. Furthermore, theoretical calculations demonstrate that the Cu^δ+/Cu⁰ interfaces lower the activation energy barrier for *CO dimerization, and hydroxyl species stabilize the *COH intermediate via hydrogen bonding, thereby promoting C₂H₄ production. Such molecule engineering modulated electronic structure provides a promising strategy to achieve highly selective CO₂ reduction to value-added chemicals.     

Synthesis of some 3‐aryl‐1H‐isochromene‐1‐thiones

A rapid microwave‐accelerated thionation of some 3‐substitued isocoumarins to corresponding 1‐thio‐isocoumarins was achieved employing Lawesson's reagent under solventless conditions.