A Thermally Induced Low-temperature Intramolecular Redox Reaction of bis(pyridine)silver(I) Permanganate and its hemipyridine Solvate

Among the known three pyridine complexes of silver permanganate, i.e. [Agpy₂]MnO₄ (1), [Agpy_2.25]MnO₄ or 7[Agpy₂]MnO₄[Agpy₄]MnO₄ (2) and [Agpy₂]MnO₄0.5py (3), compounds (1) and (2) were studied by means of thermal analysis and TG-MS methods. Presuming identical structural motifs for the Agpy₂MnO₄ blocks in (1) as it has been found in its solvate (3) by single-crystal diffraction, α-C–H...O–Mn H-bonded structures are responsible for a thermally induced low-temperature intramolecular redox reaction observed for the first time between the [Agpy₂]⁺ cation and permanganate anion.     

Role of sulfur compounds in the detection of amino acids by ninhydrin on TLC plate

Three new sulfur reagents for specific identification of amino acids on thin-layer chromatography plates have been introduced. These three sulfur containing reagents are capable of developing various distinguishable colors with many of them. A probable mechanism for such color formation is proposed.     

Studies on the structure and thermal behaviour of the Mn—urea complex

The urea complex of manganese was synthesized and its structure established to be [Mn(Urea)(H₂O)₃Cl₂] from elemental analyses, IR and UV and visible spectroscopy and magnetic susceptibility measurements. The thermal behaviour has been studied by thermogravimetry (TG) in nitrogen and air atmospheres and differential thermal analysis (DTA) in air. TG analysis shows three main steps of decomposition leading to oxide formation in the final stage when the complex is heated in air, and MnCl₂ formation when it is heated in nitrogen. The kinetics of decomposition of the complex have been studied. Plots of the Coats—Redfern equation show two breaks from which three values of the activation energy are reported. From the results, it is concluded that decomposition of the complex is a heterogeneous process.     

Non-linear wave packet dynamics of coherent states

We have compared the non-linear wave packet dynamics of coherent states of various symmetry groups and found that certain generic features of non-linear evolution are present in each case. Thus the initial coherent structures are quickly destroyed but are followed by Schrödinger cat formation and revival. We also report important differences in their evolution.     

Synthetic Studies on 2H-Thiopyran Compounds: A Reinvestigation of the Reaction Between Benzaldehydes and Sodium Sulfide

An investigation regarding the synthesis of 2H-thiopyran compounds from substituted benzaldehydes with sodium sulfide (Na₂S·10H₂O) in aqueous ethanol was carried out. The structural elucidation of the products was performed by spectroscopic methods and in one example as X-ray crystallographic analysis. A plausible mechanistic pathway is also proposed that is entirely different from an earlier report.     

Towards the stereoselective synthesis of inherently chiral pseudorotaxanes

Herein is reported an investigation towards the stereoselective synthesis of inherently chiral pseudorotaxanes. Chiral ammonium threads were readily prepared in five steps from racemic or enantiopure (M or P) salts of di-n-propyl-1,13-dimethoxyquinacridinium cation. Their self-assembly with DB24C8 or disymmetrically oriented DB24C8F6 rings formed pseudorotaxanes as shown by 1H and 19F NMR spectroscopy as well as MS measurements. A determination of the association constants (Ka) was afforded. The crucial role played by the ammonium counter-ion in the threading process was further demonstrated as salts of TRISPHAT (tris(tetrachlorobenzenediolato)phosphate(V)) anion were quite more effective than their PF6- analogues (x 7.3). A general lack of diastereoselectivity (de 相似文献   

Intensity correlation properties of high-order optical vortices passing through a rotating ground-glass plate

We study the intensity correlation properties of optical vortices passing through a rotating ground-glass (RGG) plate and compare them with those of the TEM(00) mode of an He-Ne laser beam passed through the same RGG. We have observed that the intensity correlation curves for optical vortices decrease much faster than the corresponding curve for a TEM(00) mode of the He-Ne laser. The rate of decay of the correlation increases with the increase of order of the vortices. Our experimentally observed results are supported by exact analytical results.     

Die Viskosität von Eisenphosphatsol bei variierenden Drucken

Ohne Zusammenfassung übersetzt von Rudolf K?hler (Leipzig).