Molecular tripods showing fluorescence enhancement upon binding to streptavidin

We introduce a new approach to biotin-streptavidin assays based on a molecular tripod which consists of biotin, a fluorophore, and a quencher. The interaction between streptavidin and molecular tripods perturbs the ground-state quencher-fluorophore dimeric conformation in the absence of streptavidin and diminishes the intrinsic self-quenching of a quencher-fluorophore pair. The emission intensity of the molecular tripods plus streptavidin is 3.5-5.2 times that of molecular tripods in the absence of streptavidin.     

Cycloadducts of 1‐Alkyl‐1,2‐diphospholes with N‐Phenylmaleimide: Synthesis,Structure, Oxidation,and Thionation Reactions

The [4+2] cycloaddition reaction of 1‐alkyl‐1,2‐diphospholes ( 1 ) with N‐phenylmaleimide proceeds at 25°С in toluene to give 1,7‐diphosphanorbornenes ( 2 ) as anti‐endo isomer only. Oxidation of 2 with air at room temperature or thionation with excess of sulfur at 80°С results in the formation of mixed valent P^III, P^V 7‐oxo(thia)‐1,7‐diphosphanorbornenes ( 3 , 4 ) in high yield. The polycyclic compounds 3 and 4 are air stable and have small sums of valence angles at the phosphorus atoms.     

Spatial coherence of a polariton condensate

We perform Young's double-slit experiment to study the spatial coherence properties of a two-dimensional dynamic condensate of semiconductor microcavity polaritons. The coherence length of the system is measured as a function of the pump rate, which confirms a spontaneous buildup of macroscopic coherence in the condensed phase. An independent measurement reveals that the position and momentum uncertainty product of the condensate is close to the Heisenberg limit. An experimental realization of such a minimum uncertainty wave packet of the polariton condensate opens a door to coherent matter-wave phenomena such as Josephson oscillation, superfluidity, and solitons in solid state condensate systems.     

Phase coherence of the electrons in δ-doped gaAs

The phase coherence length of the electrons is determined by magnetoconductivity for a wide range of sheet concentrations of Si-donors and free electrons. For diffusive carrier motion a comparison of the experimental and theoretical results for weak fields shows that the weak localisation is limited by inelastic electron-electron-scattering as expected for disturbed systems. For higher magnetic fields the role of mutual electron-electron interaction is also significant.     

An Inclusion Complex of Hexamolybdate inside a Supramolecular Cage and Its Structural Conversion

A self-assembled cage compound consisting of four concave ligands and two square-planar-coordinated Pd(II) ions was found to quantitatively encapsulate a hexamolybdate dianion [Mo(6)O(19)](2-) in solution. The addition of 1 equiv more of [Mo(6)O(19)](2-) to the inclusion complex resulted in the formation of a precipitate from which single crystals were grown. X-ray analysis showed that a structural conversion had taken place upon crystallization: one hexamolybdate anion was found to be wrapped in a chiral, cyclic arrangement of three ligands in the absence of any Pd(II) ions to give a compound of the formula {[Mo(6)O(19)](2-)@(ligand)(3)+2H(+)}. We postulate the stabilization of this arrangement by attractive C-H···O and CF(3)-pyridine interactions.     

Synthese und Kristallstruktur von (PPh4)2[Mo2Cl10]

Synthesis and Crystal Structure of (PPh₄)₂[Mo₂Cl₁₀] The title compound is obtained in the reaction of [MoCl₄(Ph? C?C? Ph)]₂ with tetraphenylphosphonium chloride in dichloro methane, forming brown crystals. It is characterized by the i.r. spectrum and a crystal structure analysis by the aid of X-ray diffraction data. The complex crystallizes triclinic in the space group P1 with one formula unit per unit cell. The cell dimensions are a = 1122 pm, b = 1137 pm, c = 1283 pm; α = 63.4°, β = 69.1°, γ = 86.5°. The crystal structure determination (2959 observed, independent reflexions, R = 4.5%) shows the constants of the unit cell to consist of on centrosymmetric anion, two cations and one disordered molecule of dichloro methane. The distance Mo? Mo in the anion is 380 pm, which excludes direct magnetic interaction between the molybdenum atoms.     

Polarization transfer observables in π-d elastic scattering

Polarization transfer measurements in π⁺ elastic scattering have been performed at two incident pion energies, one below and one at the Δ(3, 3)-resonance. Using a vector polarized deuteron target four polarization transfer observables are determined. The results are compared to predictions from Faddeev calculations.