基于三苯胺和咔唑的联吡啶铱化合物的合成及其在光催化水产氢中的应用研究

以三苯胺、咔唑、4,4′-二羧基联吡啶为原料,设计并合成了两个联吡啶铱（III）配合物Ir1和Ir2,其结构经¹H NMR, ¹³C NMR和HR-MS(MALDI-TOF)表征。并利用紫外可见光谱（UV-Vis）、荧光发射光谱（Photoluminescence）和循环伏安法研究了化合物的光学和电学性质。结果表明：Ir1和Ir2的紫外可见光吸收波长分别位于456 nm 和448 nm,相应的发射波长分别为645 nm和678 nm,说明其均能利用可见光; Ir1和Ir2的HOMO电位为-5.125~-5.510 eV, LOMO电位为-2.880~-0.310 eV,满足作为光敏剂的基本条件。研究了化合物在可见光照射下光催化水分解产生氢气的效果。结果表明：Ir1和Ir2的氢气值TONs(turnover numbers)达到2 827和1 908。     

A pulsed EPR study of surfactant layer structure in composites of a synthetic layered silicate with polystyrene and polycaprolactone

Double electron electron resonance (DEER), deuterium electron spin-echo envelope modulation (ESEEM) spectroscopy and 31P electron nuclear double resonance (ENDOR) spectroscopy were applied to site-specifically spin-labeled surfactants in the organically modified layered silicate magadiite and its composites with polystyrene (PS) and polycaprolactone (PCL). The organomagadiite consist of stacks of silicate platelets with surfactant layers between these platelets. In PS composites the stacks are dispersed in the polymer matrix as a whole, while melt processing with PCL leads to intercalation of polymer chains into the galleries between the platelets. The DEER data prove that even in the case of the non-intercalated PS composites the density of surfactant molecules changes drastically during composite formation on length scales of a few nanometers. Deuterium ESEEM data demonstrate that spin labels attached both in the middle and at the end of the alkyl chain have contact with the headgroups of neighboring surfactant molecules. By analysis of the 31P ENDOR spectra, two characteristic distances are found between the spin labels and the headgroups of phosphonium surfactants. The shorter, proximal distance can be assigned to headgroups in the same surfactant layer. By comparison with the basal spacing between consecutive silicate platelets the longer, distal distance is assigned to a layer of surfactants that is not attached to the surface of the next platelet but rather located between platelets. Altogether the data support a picture of trilayers of disordered surfactant molecules with their alkyl chains oriented nearly parallel to the surface.     

Methane Oxidation over Cu2+/[CuOH]+ Pairs and Site-Specific Kinetics in Copper Mordenite Revealed by Operando Electron Paramagnetic Resonance and UV/Visible Spectroscopy

Cu-exchanged mordenite (MOR) is a promising material for partial CH₄ oxidation. The structural diversity of Cu species within MOR makes it difficult to identify the active Cu sites and to determine their redox and kinetic properties. In this study, the Cu speciation in Cu-MOR materials with different Cu loadings has been determined using operando electron paramagnetic resonance (EPR) and operando ultraviolet-visible (UV/Vis) spectroscopy as well as in situ photoluminescence (PL) and Fourier-transform infrared (FTIR) spectroscopy. A novel pathway for CH₄ oxidation involving paired [CuOH]⁺ and bare Cu²⁺ species has been identified. The reduction of bare Cu²⁺ ions facilitated by adjacent [CuOH]⁺ demonstrates that the frequently reported assumption of redox-inert Cu²⁺ centers does not generally apply. The measured site-specific reaction kinetics show that dimeric Cu species exhibit a faster reaction rate and a higher apparent activation energy than monomeric Cu²⁺ active sites highlighting their difference in the CH₄ oxidation potential.     

Possible Supernova Multi-Explosions and Induced Gravitational Collapse

In this paper, three hotly discussed problems, namely the neutrino bursts, the blue progenitor, and the mixing phenomenon, observed in SN1987A are summarized. But it is pointed that while all the observations on SN1987A do not favour a twice-banged scenario, we have found three historical cases from ancient Chinese documents that might be interpreted as twice- or even multi-explosions of a supernova. Finally in a one-dimensional simulation we demonstrate that an induced gravitational collapse b possible.     

COMMENTS ON THE NEW NEUTRINO "BALANCE": A DISCUSSION OF THE FEASIBILITY OF USING THE ELECTRON CAPTURE PROCESS IN158Tb, 157Tb FOR NEUTRINO MASS DETERMINATION

It is found that owing to the large energy difference in K-and L-shells of the daughter atom, ¹⁵⁸Tb is not the best candidate for neutrino "balance". Instead, ^l57Tb can offer a better chance for. neutrino mass determination if the Q-value 55 far obtained is verified. If it is so,then the relevant atomic calculation with high precision is very necessary. It is shown that to include the radiative correction in the Hartree-Fock calculation is very important for such atoms as ¹⁵⁷Gd and ¹⁵⁷Tb.     

APPROXIMATE B.S. WAVE FUNCTIONS FOR AN ELECTROMAGNETIC BOUND SYSTEM OF SPINS (1/2, 1/2) OR (1/2, 1/2) WITH UNEQUAL MASSES

The Bethe-Salpeter equation for an electromagnetic bound system of spins (1/2—1/2) or (1/2—1/2) with unequal masses are solved in this paper. The approximate B.S. wave functions for these systems are given. Utilising these wave functions, the decay rate and branching ratio for Ξ⁰→(Σ⁺μ^－)+v_μ are calculated with accuracy up to order O(α). The results are wΞ⁰→(Σ⁺μ^－)+v_μ1.12(1/sec) and R=[wΞ⁰→(Σ⁺μ^－)+v_μ]/[wΞ⁰→(Σ⁺μ^－)+v_μ]4.7×10^-7. Similarly, the process Λ→(pμ^－)+v_μ is also discussed.     

AN EXPLANATION TO THE INCONSISTENT PHENOMENON BETWEEN MEAN MULTIPLICITY AND AVERAGE TRANSVERSE MOMENTUM IN COSMIC RAY EXPERIMENTS WITH SUPERHIGH ENERGY OF E > 1015 eV

The rapid increase of both and T> as S increases in superhigh energy cosmic ray experiments manifests some inconsistencies with the 1> ≤ π/4 S^1/2 rule. It is shown that these inconsistencies can be weakened with the assumption that only the secondary particles of the small fireballs are measured in the Ashtonsr experiment ^[3], but still not removed.