Ein allgemeiner Mengenisomorphiesatz der Theorie der Verbände

Ohne Zusammenfassung     

Perspektivitäten in allgemeinen Verbänden

Ohne ZusammenfassungAnmerkung der Redaktion. Die Arbeit wurde am 25. Dezember 1943 eingereicht, vor dem Druck jedoch umgearbeitet, um den Zusammenhang mit nachfolgenden Arbeiten zu verdeutlichen und diese vorzubereiten.     

The formation of Lewis acid/base stabilised phosphanyltrielanes - A theoretical and experimental study

Theoretical investigations on the thermochemistry and the reaction mechanism of the formation of Lewis acid/base stabilised phosphanyltrielanes D · H₂EPH₂ · A (D = Lewis base, A = Lewis acid) were conducted. The reactions of EH₃ · D with A · PH₃ to form D · H₂EPH₂ · A and H₂ (E = B, Al, Ga; D = NH₃; A = BH₃, Cr(CO)₅) are all exothermic, regardless of whether donors and acceptors are present or absent. The lithium chloride elimination reactions between EH₂Cl · D and A · PH₂Li to give D · H₂EPH₂ · A and LiCl are endothermic for donor/acceptor stabilised compounds, if formation of gaseous LiCl is considered. If solid lithium chloride is considered all reactions are strongly exothermic. Studies of the transition state for H₂-elimination reactions between EH₃ · D and A · PH₃ to yield D · H₂EPH₂ · A and H₂ were only successful for E = Al, Ga. In these cases the reaction proceeds via a transition state featuring a five or six-coordinate group 13 element. Different donor molecules do not influence the activation energy of such H₂-elimination reactions, but nevertheless they have an effect on the reaction energy. The synthesis of the Cr(CO)₅ substituted phosphanyltrielanes [(CO)₅Cr(H₂PBH₂ · NMe₃)] (3a) and [(CO)₅Cr(H₂PAlH₂ · NMe₃)] (3b), as well as of the dinuclear complex [(CO)₈Cr₂(μ-HPBH₂ · NMe₃)₂] (4) are described, the latter as a subsequent reaction product of the photolysis of 3a. All compounds were characterised spectroscopically and by X-ray structure analysis.     

Separate deprotonation reactions converge mechanistically for a new cyclization of benzyl 1-alkynyl sulfones

A heretofore unknown LDA-induced conversion of benzyl 1-alkynyl sulfones to 1H-2-benzothiopyran-S,S-dioxides is demonstrated. A benzyl carbanion, accessible by two means, is thought to cyclize by temporary disruption of aromaticity. Key intermediates are observed by ReactIR analysis. Thiophene derivatives are also amenable to cyclization, forming 7H-thieno[2,3-c]thiopyran-S,S-dioxides.     

Fullerene derived molecularly imprinted polymer for chemosensing of adenosine-5′-triphosphate (ATP)

For molecular imprinting of oxidatively electroactive analytes by electropolymerization, we used herein reductively electroactive functional monomers. As a proof of concept, we applied C₆₀ fullerene adducts as such for the first time. For that, we derivatized C₆₀ to bear either an uracil or an amide, or a carboxy addend for recognition of the adenosine-5′-triphosphate (ATP) oxidizable analyte with the ATP-templated molecularly imprinted polymer (MIP-ATP). Accordingly, the ATP complex with all of the functional monomers formed in solution was potentiodynamically electropolymerized to deposit an MIP-ATP film either on an Au electrode of the quartz crystal resonator or on a Pt disk electrode for the piezoelectric microgravimetry (PM) or capacitive impedimetry (CI) determination of ATP, respectively, under the flow-injection analysis (FIA) conditions. The apparent imprinting factor for ATP was ∼4.0. After extraction of the ATP template, analytical performance of the resulting chemosensors, including detectability, sensitivity, and selectivity, was characterized. The limit of detection was 0.3 and 0.03 mM ATP for the PM and CI chemosensor, respectively. The MIP-ATP film discriminated structural analogues of ATP quite well. The Langmuir, Freundlich, and Langmuir–Freundlich isotherms were fitted to the experimental data of the ATP sorption and sorption stability constants appeared to be nearly independent of the adopted sorption model.     

Pseudopotential calculations for hydrogen centers in ionic crystals

Pseudopotential cluster calculations have been performed for hydrogen centers H⁰_i, H⁰_a, H⁰_c in XF and XCl ionic crystals (X = Li, Na, K, Rb). Results are given for interatomic potentials, for frequencies of localized vibration modes and for activation energies for diffusion of the hydrogen centers.     

Phase-matched third-harmonic generation of Nd: Glass-laser picosecond pulses in a new cyanine-dye solution

The phase-matched direct tripling of picosecond light pulses of a mode-locked Nd: glass laser in a new cyanine dye PMC is studied. The solvents trifluoroethanol (TFE) and hexafluoroisopropanol (HFIP) are applied. The S ₀–S ₁ absorption peak of the dye is around =480 nm and the absorption cross section at the third-harmonic wavelength of ₃=351.3 nm is only ₃1×10^–19 cm². Phase-matching occurred at concentrations of C_PM=0.0874 mol/dm³ in HFIP and 0.1088 mol/dm³ in TFE. A third-harmonic energy conversion efficiency of _E0.01 was achieved at a pump-laser peak intensity of I _0L2.5×10¹¹ W/cm² in a 5 mm long sample of PMC in TFE. The conversion efficiency is limited by destruction of phase-matching due to the intensity-dependent nonlinear refractive index of the dye solutions.