Diselenadiphosphetandiselenide und Triselenadiphospholandiselenide – Synthese und Charakterisierung mittels 31P‐ und 77Se‐Festkörper‐NMRSpektroskopie

Diselenadiphosphetane Diselenides and Triselenadiphospholane Diselenides – Synthesis and Characterization by ³¹P and ⁷⁷Se Solid‐State NMR Spectroscopy 1,3‐Diselena‐2,4‐diphosphetane‐2,4‐diselenides (RPSe₂)₂ with R = Me, Et, t‐Bu, Ph, 4‐Me₂NC₆H₄, 4‐MeOC₆H₄ have been synthesized by different methods. The insoluble compounds were investigated by ³¹P and ⁷⁷Se solid‐state NMR and the purity of the compounds has been checked by their CP MAS sideband NMR spectra. The structure of the investigated compounds has been confirmed by the isotropic and anisotropic values of the chemical shifts and the ¹J_P–Se coupling constants. In addition, two new 1,2,4‐triselena‐3,5‐diphospholane‐3,5‐diselenides, (RPSe₂)₂Se (R = Me, Et), formed under similar synthesis conditions, were investigated. Their structure was derived from the ⁷⁷Se satellites of ³¹P solution spectra and from solid‐state spectra. For (t‐BuPSe₂)₂ the experimentally obtained principal values of phosphorus and selenium shielding tensors are compared with values from IGLO calculations (HF und SOS DFPT). The calculated orientations of the principal axes are discussed.     

Low Temperature Syntheses of Highly-ordered Framework Materials: The Aluminium Phosphate Ammonium Taranakite

The formation of a highly crystalline ammonium analogue of the aluminium phosphate mineral taranakite at ambient temperature and above is described. The high crystallinity and ordering of the products obtained when ammonium is used as a templating agent suggests that it is intimately involved in the structure. At long crystallization times and at higher temperatures, transformation to the framework structure of AlPO₄-15 occurs. Results from powder x-ray diffraction, solid state NMR, electron microscopy, thermal and element analyses are presented and discussed. They demonstrate the high degree of crystallinity and ordering of the taranakite samples synthesized by this method. These results – in particular the very mild synthesis conditions – suggest the possibility that there may be sequestering of ammonium phosphate fertilizers in form of NH₄-taranakite from their interaction with clay materials in soils.     

关于Jordan and Wigner玻色化方案的讨论

传统根据Ｊｏｒｄａｎ和Ｗｉｇｎｅｒ理论,构造了费米子玻色化方案。文中的讨论证明了这种方案只在ｋ≠ｋ’时则不成立,从而说明了费米子的玻色化方案是不完备的。     

Oxidation triggers guest dissociation during reorganization of an FeII4L6 twisted parallelogram

A three-dimensional Fe^II₄L₆ parallelogram was prepared from ferrocene-containing ditopic ligands. The steric preference of the bulky ferrocene cores towards meridional vertex coordination brought about this new structure type, in which the ferrocene units adopt three distinct conformations. The structure possesses two distinct, bowl-like cavities that host anionic guests. Oxidation of the ferrocene Fe^II to ferrocenium Fe^III causes rotation of the ferrocene hinges, converting the structure to an Fe^II₁L₁⁺ species with release of anionic guests, even though the average charge per iron increases in a way that would ordinarily increase guest binding strength. The degrees of freedom exhibited by these new structures – derived from the different configurations of the three ligands surrounding a meridional Fe^II center and the rotation of ferrocene cores – thus underpin their ability to reconfigure and eject guests upon oxidation.

An oxidation-triggered twist in its ferrocene ligands causes an Fe₄L₆ parallelogram to release its guests and collapse into a high spin Fe₁L₁ structure.     

Privileged Structures Revisited

Privileged structures inspire compound library design in medicinal chemistry. We performed a comprehensive analysis of 1.4 million bioactive compounds, with the aim of assessing the prevalence of certain molecular frameworks. We used the Shannon entropy formalism to quantify the promiscuity of the most frequently observed atom scaffolds across the annotated target families. This analysis revealed an apparent inverse relationship between hydrogen-bond-acceptor count of a scaffold and its potential promiscuity. The results further suggest that chemically easily accessible scaffolds can serve as templates for the generation of bespoke compound libraries with differing degrees of multiple target engagement, and heterocyclic, sp³-rich frameworks are particularly suited for target-focused library design. The outcome of our study enables us to place some of the many narratives surrounding the concept of privileged structures into a critical context.     

Deorphaning Pyrrolopyrazines as Potent Multi‐Target Antimalarial Agents

The discovery of pyrrolopyrazines as potent antimalarial agents is presented, with the most effective compounds exhibiting EC₅₀ values in the low nanomolar range against asexual blood stages of Plasmodium falciparum in human red blood cells, and Plasmodium berghei liver schizonts, with negligible HepG2 cytotoxicity. Their potential mode of action is uncovered by predicting macromolecular targets through avant‐garde computer modeling. The consensus prediction method suggested a functional resemblance between ligand binding sites in non‐homologous target proteins, linking the observed parasite elimination to IspD, an enzyme from the non‐mevalonate pathway of isoprenoid biosynthesis, and multi‐kinase inhibition. Further computational analysis suggested essential P. falciparum kinases as likely targets of our lead compound. The results obtained validate our methodology for ligand‐ and structure‐based target prediction, expand the bioinformatics toolbox for proteome mining, and provide unique access to deciphering polypharmacological effects of bioactive chemical agents.     

强激光反射镜热畸变对光束传输特性的影响

 通过等效净吸收功率密度方法获取了强激光反射镜热畸变的干涉图像，提出了热畸变反射镜在平面波照射下近场波面畸变与远场光斑的计算方法，探讨了强激光远场光斑测试的一种新思路。定量分析结果表明，对单晶硅镜，在净吸收功率210W，光照时间为6s时，最大热畸变达到0.76μm，由此造成的近场波面Zernike离焦系数为0.32μm，x方向和y方向彗差分别为0.13μm和0.22μm， x方向倾斜系数上升到0.12μm，光束质量因子达5.7。     

在激光大气传输中利用SBS阈值效应实现小面积信标的研究

 在理论上建立起将受激布里渊散射（SBS）与激光大气传输过程相结合的激光补偿传输的数学模型,并进行了数值模拟，提出并证明了利用SBS阈值效应可以将相位共轭光会聚到目标上一个小面积上，从而在目标上主动获得小面积信标光斑。利用SBS实现激光大气补偿传输（传输距离250m）的实验研究,证实了上述理论预期。