Anhydrobiisatic acid 6:12-Oxa-5:6:11:12-tetrahydrophenhomazine-6:12-dicarboxylic acid

Anhydrobiisatic acid (IVa), a new type of compound containing the phenhomazine ring system, has been obtained by self-condensation of isatic acid—(o-aminophenyl)glyoxylic acid—. The structure of this acid has been established and derivatives have been prepared. N:N′-Dimethylanhydrobiisatic acid (IVc) has been resolved into optically active components.     

Die Massenspektren von Pd6Cl12, Pt6Cl12 und PdnPt6−nCl12

Mass Spectra of Pd₆Cl₁₂, Pt₆Cl₁₂, and Pd_nPt_6?nCl₁₂ Pd₆Cl₁₂, and Pt₆Cl₁₂ and both together are volatilised in a mass spectrometer. 3 Cl and 1 Pd have approximately the same mass, therefore isotopes of Pd and Pt are used (¹⁰⁸Pd, ₁₉₄Pt). With an ionisation energy of 50 eV part of the vapourised molecules is strongly fragmented. With a lower ionisation energy the molecule ions Pd₆Cl₁₂⁺, Pt₆Cl₁₂⁺ and Pd_nPt_6?nCl₁₂⁺ are only observed.     

Die thermodynamische Stabilität der Molekeln Pd6Cl12, Pd6Br12 und Pt6Cl12

Thermodynamic Stability of Pd₆Cl₁₂, Pd₆Br₁₂, and Pt₆Cl₁₂ Molecules Vapour pressure data of PdCl₂ and PdBr₂ taken from the literature have been used to get new informations regarding the vapourization of Pd₆Cl₁₂ molecules. Using mixtures of PdCl₂ and AgBr as source materials, besides Pd₆Cl₁₂ molecules the vapourization of Pd₆Cl_12-nBr_n with n = 1 – 8 has been observed in a mass spectrometer. Semi quantitative observations concerning the vapourization of Pt₆Cl₁₂ molecules from a PtCl₂ solid are reported. Heats of formation and standard entropy data for the molecules Pd₆Cl₁₂, Pd₆Br₁₂ and Pt₆Cl₁₂ are given.     

Hochdrucksynthese von BaSr2P6N12 und BaCa2P6N12 und Strukturvergleich der Reihe BaP2N4, BaCa2P6N12 und BaSr2P6N12

High‐Pressure Synthesis of BaSr₂P₆N₁₂ and BaCa₂P₆N₁₂ and Comparison of the Structures of BaP₂N₄, BaCa₂P₆N₁₂, and BaSr₂P₆N₁₂ The novel nitridophosphates BaCa₂P₆N₁₂ and BaSr₂P₆ N₁₂ were obtained by means of high‐pressure high‐temperature synthesis utilizing the multianvil technique (1200 °C, 5 GPa). The complex anion [PN₂^?] of the title compound is formally isoelectronic with silica. The crystal structure was solved from powder data and refined by the Rietveld method (BaCa₂P₆N₁₂: , Z = 4, a = 9,9578(2) Å; BaSr₂P₆N₁₂: , Z = 4, 10,0705(2) Å). The crystal structures are derived from that of BaP₂N₄ which is isotypic with a high pressure phase of CaB₂O₄ and BaGa₂S₄. For each compound the ³¹P solid state NMR spectrum yielded a single resonance (BaCa₂P₆N₁₂: 7.4 ppm; BaSr₂P₆N₁₂:3.9 ppm).     

Zwei neue Erdalkalimetall-Oxoindate: BaCa2In6O12 und BaSr2In6O12

Two New Alkaline-Earth-Oxoindates: BaCa₂In₆O₁₂ and BaSr₂In₆O₁₂ The hitherto unknown compounds (I): BaCa₂In₆O₁₂ and (II): BaSr₂In₆O₁₂ were prepared and examined by single crystal X-Ray work. (I) and (II) crystallize with hexagonal symmetry, space group C? P6₃/m, with (I): a = 9.880, c = 3.211 Å; (II): a = 9.9443; c = 3.2671 Å, Z = 1. Both compounds are isotypic to the metastable oxide AM₂Ln₆O₁₂, but without metastable behavior. The [In₆O₁₂]^6? network is occupied by the alkaline earth ions. One of the tunnels is stuffed by Ca²⁺ and Sr²⁺ respectively, the other one by Ba²⁺ in a statistical distribution on possible point positions. (I) and (II) prove the existence of the AM₂Ln₆O₁₂-type in respect to small Ln³⁺ ions.     

Investigation of solution‐grown,chain‐folded lamellar crystals of the even‐even nylons: 6 6, 8 6, 8 8, 10 6, 10 8, 10 10, 12 6, 12 8, 12 10, and 12 12

Chain‐folded lamellar crystals of the ten even‐even nylons: 6 6, 8 6, 8 8, 10 6, 10 8, 10 10, 12 6, 12 8, 12 10, and 12 12 have been grown from solution and their morphologies and structures studied using transmission electron microscopy, both imaging and diffraction. Sedimented mats were examined using X‐ray diffraction. The solution‐grown crystals are lath‐shaped lamellae and diffraction from these crystals, at room temperature, reveals that three crystalline forms are present in differing ratios. The crystals are composed of chain‐folded, hydrogen‐bonded sheets, the linear hydrogen bonds within which generate a progressive shear of the chains (p‐sheets). The sheets are found to stack in two different ways. Some p‐sheets stack with a progressive shear, to form the “α_p structure”; others sheets stack with an alternate stagger, to form the “β_p structure”. Both the α_p and β_p structures give two strong diffraction signals at spacings of 0.44 nm and 0.37 nm; these signals represent a projected intrasheet interchain distance (actual value 0.48 nm) and the intersheet spacing, respectively. Preparations of nylons 6 6, 8 6, 8 8, 12 6, and 12 8 consisted almost entirely of α_p‐structure material, with only a trace of β_p‐structure material being present. In contrast, nylons 10 6, 10 8, 10 10, 12 10, and 12 12 contained substantial quantities of both α_p‐ and β_p‐structure material, with α_p‐structure material always being in the majority. Preparations of nylons 10 8, 12 10, and 12 12 also showed an additional diffraction signal at 0.42 nm; this signal is characteristic of the pseudohexagonal (high temperature) structure. The melting temperature of solution‐grown lamellae of these even‐even nylons decreases with decreasing linear amide density. On heating, the strong diffraction signals (0.44 nm and 0.37 nm) gradually moved together and merge at the Brill temperature to form a single diffraction signal (0.42 nm), characteristic of the pseudohexagonal structure. This single diffraction signal remained until melting. For nylons 6 6, 8 6, 8 8, 10 6, and 12 6, the Brill temperatures were substantially below the respective melting temperatures and the single 0.42 nm diffraction signal was stable over temperature ranges of 14 °C to 56 °C, depending on the nylon. Conversely, nylons 10 8, 10 10, 12 8, 12 10, and 12 12 had coincident melting and extrapolated Brill temperatures. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1209–1221, 2000     

12. Österreichische Chemietage

Joint Meeting of the Slovenian & Austrian Chemical Societies, September 10 – 13, 2007, Alpen‐Adria‐Universität Klagenfurt     

Drei Wege zur Oxydation von [Ta6Cl12]2+ ([Ta6Br12]2+ und [Nb6Cl12]2+)

Three Oxidation Paths of [Ta₆Cl₁₂]²⁺ ([Ta₆Br₁₂]²⁺ and [Nb₆Cl₁₂]²⁺) [Ta₆Cl₁₂]²⁺ is oxidized autocatalytically to [Ta₆Cl₁₂]⁴⁺ by HNO₃. The titration of [Ta₆Cl₁₂]²⁺ with KBrO₃ (in HBr-containing solutions) or with Ce⁴⁺ or K₂Cr₂O₇ (in HNO₃-containing solutions) leads to a clear [Ta₆Cl₁₂]³⁺ step. The further titration leads beside [Ta₆Cl₁₂]⁴⁺ to the formation of Ta₂O₅(· xH₂O). [Ta₆Cl₁₂]²⁺ behaves with KBrO₃(+ HBr) equally, but the formation of [Ta₂O₅](· xH₂O) is only small. [Nb₆Cl₁₂]²⁺ (22°C) titrated with Ce(ClO₄)₄ in 2n HClO₄ gives the first potential step nearby exact ([Nb₆Cl₁₂]³⁺) and at a very slow titration in a second step a precipitation of Nb₂O₅(· xH₂O) occurs, which adsorbed Ce⁴⁺ additionally. At ?15°C with Ce(ClO₄)₄ the first potential step was exactly at [Nb₆Cl₁₂]^2+→3+, while the second step needs a distinct additional consumption of titer. (Formation of [Nb₆Cl₁₂]⁴⁺ and beside it [Nb₂O₅](· xH₂O)). From the titration curves and sections of its normal progress in all cases we get the normal potentials 2+/3+ and 3+/4+ with an accuracy of ± 0.01 volt. In alkaline solution the complexes are oxidized with air-oxygen to [M₆X₁₂](OH)₆^2?, while the Br-containing complexes suffer hydrolysis afterwards.     

Enantiopure Polyradical Tetrahedral Pd12L6 Cages

The synthesis of cages with a polyradical framework remains a challenging task. Herein is reported an enantiomeric pair of quinoid-bridged polyradical tetrahedral palladium(II) cages that are stabilized by an unusual dianionic diradical form (dhbq^..2−). These cages have been characterized by electron paramagnetic resonance and UV-visible spectroscopy, squid magnetometry and mass spectrometry. Single-crystal-derived X-ray investigations of the iso-structural cages built on fluoranilate linkers confirm the tetrahedral structure of the obtained radical cages. Theoretical calculations showed that the diradical state of the dhbq anions is more stable than the usual monoradical state. A weak ferromagnetic exchange between adjacent radical centers was observed in DFT studies.     

Synthesis of 6, 9, 11-Trihydroxy-6a, 12a-dehydrorotenoid

6, 9, 11-Trihydroxy-6a, 12a-dehydrorotenoid 1 (coccineone B) was synthesized from 2-hydroxybenzaldehyde 2 and phloroglucinol.     

Gemini表面活性剂(12-6-12)和DNA的相互作用

应用紫外光谱、荧光探针、zeta 电位、动态光散射和凝胶电泳等方法探讨了阳离子gemini 表面活性剂C₁₂H₂₅N⁺(CH₃)₂―(CH₂)₆―(CH₃)₂N⁺C₁₂H₂₅·2Br^-(12-6-12)与DNA之间的相互作用. 研究结果表明, 与传统表面活性剂相比, 偶联表面活性剂特殊的分子结构使其与DNA的作用更强烈. DNA引导表面活性剂在其链周围形成类胶束结构, 开始形成类胶束时对应的表面活性剂临界聚集浓度(CAC)比纯表面活性剂临界胶束浓度(CMC)低两个数量级. CAC与DNA的浓度无关, 而与表面活性剂之间的疏水作用以及表面活性剂与DNA之间的静电吸引作用密切相关. Zeta 电位和凝胶电泳结果显示了DNA链所带负电荷逐渐被阳离子表面活性剂中和的过程. 借助原子力显微镜(AFM)成功观察到了松散的线团状DNA, 球状体随机地分散在DNA链上形成类似于串珠的结构、尺寸较大的球形复合物以及其由于吸附多余的表面活性剂重新带正电而被溶解得到的较小DNA/12-6-12聚集体. 圆二色(CD)光谱结果显示, 12-6-12可以诱导DNA的构象发生改变.