Ein stabiles Trichlor‐oxyphosphoran mit einem Oxaphosphorinring

A stable Trichloro‐oxyphosphorane with an Oxaphosphorine Ring The cyclic, aryl‐substituted chlorophosphonite 3 reacts with chlorine to give the trichloro‐oxyphosphorane 4 (6, 6, 6‐trichloro‐6H‐dibenzo[c, e]1, 2‐oxaphosphorine). The stability of the phosphorane is solvent‐dependent.     

Stereoselectivity of an ω-transaminase-mediated amination of 1,3-dihydroxy-1-phenylpropane-2-one

The stereoselectivity of a recently isolated ω-transaminase from Chromobacterium violaceum in the amination of 1,3-dihydroxy-1-phenylpropan-2-one has been determined. The enzyme is not enantioselective towards a racemic mixture of 1,3-dihydroxy-1-phenylpropan-2-one but is highly stereoselective forming (2S)-2-amino-1-phenyl-1,3-propanediols in >99% ee.     

Aquacyanocobalt(III)-cobyrinate as a key compound in NO2-sensitive polymeric liquid membranes.

The reactions within a recently introduced NO2-sensitive polymeric membrane based on aquacyanocobalt(III)-cobyrinate are described. The detailed reaction mechanism was investigated in three ways: using UV/VIS-spectroscopy, determining the reaction products and investigating the influence of other gases. It could be shown that the membrane's high sensitivity and selectivity derives from the remarkable reaction of NO2 with this cobyrinate derivative, which yields nitric and nitrous acid. This reaction can be transduced with a consecutive protonation of the included chromoionophore into an optical signal, which allows the detection of NO2 in the ppb-range.     

Preparation and morphology of pyramidal MFI single-crystal segments

Single-crystal segments of tetra-n-propylammonium-templated Silicalite-1 and ZSM-5 were prepared by postsynthetic treatment of twinned MFI prisms. Microwave irradiation of the parent crystallites in alkaline solution containing hydrogen peroxide, followed by ultrasound treatment, led to disintegration of the zeolite prisms. The resulting wedge-shaped crystal segments proved to be single crystals of excellent crystallinity as shown by optical and X-ray investigations. The hydroxyl ions, compensating the positive charges of the tetrapropylammonium cations, were located by single-crystal structure refinement in template-containing Silicalite-1 and ZSM-5 but absent from the calcined samples.     

Electrophilicity parameters for 2-benzylidene-indan-1,3-diones--a systematic extension of the benzhydrylium based electrophilicity scale

Kinetics of the reactions of four 2-benzylidene-indan-1,3-diones (1a-d) with carbanions (2a-I) have been studied photometrically in dimethyl sulfoxide solution at 20 degrees C, and the electrophilicity parameters E were determined by the linear free energy relationship log k(2)(20 degrees C) = s(N + E) (eqn (1)). The rate-determining step of these reactions is the nucleophilic attack of the carbon nucleophile at the double bond of the Michael acceptor. Comparisons with literature data show that the linear free energy relationship (eqn (1)) allows the semiquantitative prediction of the reactivities of 2-benzylidene-indan-1,3-diones towards various nucleophiles.     

Engineering of efficient phosphorescent iridium cationic complex for developing oxygen-sensitive polymeric and nanostructured films

In this study, a novel phosphorescent Ir(III) complex [Ir(2-phenylpyridine)2(4,4'-bis(2-(4-N,N-methylhexylaminophenyl)ethyl)-2-2'-bipyridine)Cl] (for convenience, the complex was given the synonym N-948) has been designed and synthesized, to be used as an oxygen probe. It was characterized by spectroscopic and analytical methods when incorporated in a polystyrene and nanostructured metal oxide support. N-948 is the first Ir complex in the literature with a luminescence emission at a wavelength higher than 650 nm (665 nm), with a quantum yield higher than 0.50 (0.58 +/- 0.05) and an extremely long phosphorescence lifetime (102 micros) which has been used for developing oxygen-sensitive films. In addition, the new complex shows a Stern-Volmer constant which is 20 times higher than that of other Ir complexes known from the literature when they are immobilized in polystyrene. The sensing film shows long-term stability (up to 12 months), complete reversibility of the signal quenched by oxygen and a quick response time to various oxygen concentrations (<2 s changing from 10 vol% pO2 to 90 vol% pO2). Thus, it is an interesting and promising complex for developing oxygen-selective sensors for gas analysis and the analysis of dissolved oxygen.