Photophysical Properties of Fluorescent Polymers Containing 1,10-Phenanthroline-3,8-ylene and Diethinylenebenzene Units and Their Model Compounds: A Comparison to 2,2′-Bipyridine Analogues

Investigation of the absorption and emission spectra (stationary and time-resolved) of phenanthroline-based polymers shows that the enforcement of a cisoid geometry in the bipyridine unit of the main chain via an ethenylene bridge does not significantly change the spectral and the deactivation behaviour. In close analogy to similar polymers, containing bipyridine units, the conjugation length in these polymers does not exceed ca. two chromophore units. At low temperatures, the model compounds show an additional, bathochromically shifted, intense luminescence with an increased lifetime which can be interpreted as an excimer (or aggregate) fluorescence. In addition, broad, superimposed emission bands arising from various aggregated species are observed. The relative intensity of these bands depends on the temperature processing occurring during cooling. Intersystem crossing is an insignificant deactivation channel.     

A simple method of target preparation for the bulk analysis of powder samples by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS)

A simple and rapid procedure using a glue technique has been developed for the preparation of stable targets from powder samples for bulk analysis by LA– ICP–MS. The procedure was evaluated for the analysis of trace elements in SiC, of rare-earth elements in different types of silicate (rocks, sediments, and soils), and of Au and platinum-group elements in geological silicates. The test analysis was conducted using an IR laser in combination with a quadrupole mass spectrometer. The recommended preparation procedure offers the possibility of different types of calibration, for example application of certified reference samples in combination with prepared spiked samples on a base of a natural or synthetic matrix, or addition calibration. The resulting calibration functions are linear over a range of several decades. The trueness of the results was evaluated by use of certified reference samples. Analytical concentration ranges, detection limits, and the relative standard deviations are reported. Received: 20 November 2000 / Revised: 13 March 2001 / Accepted: 17 March 2001     

α-Bromo-α-ethoxy-acetic Acid Derivatives as New Alkylating Reagents

A convenient synthesis of new α-bromo-α-ethoxy-acetic acid alkylating reagents, intermediates for the synthesis of enzymatically cleavable alkoxy-carbonyl ethoxymethyl esters, is described.     

Elementarteiler von Inzidenzmatrizen symmetrischer Blockpläne

By a study of the integral code generated by the rows of the incidence matrix and its extention the following results are obtained: Let d ₁,...,d _V(d ₁|d ₂,d ₂|d ₃...) be the elementary divisors of the incidence matrix of a symmetric (v,n+, ) design. Then d _v=(n+)n/g.c.d. (n, ). Moreover, if p is a prime such that p|n, p and if x _p denotes the p-part of x, then (d _id_v+2–i) _p =n _p for 2iv. For projective planes it can be shown that d ₁=···=d _3n–2=1, hence and . The paper also contains some results about elementary divisors of incidence matrices G satisfying the condition G ^tG=nI+ J.

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Elementarteiler von Inzidenzmatrizen symmetrischer Blockpläne

     

Exact solutions for a quantum hard-core system

Exact closed expressions have been obtained for the first three partial waves of the two-particle density matrix for a hard-core pairwise interaction.     

Selbstduale Codes über dem Ring der ganzen Zahlen modulo 4

Ohne Zusammenfassung     

Synthesis of a tetra(maleimide) as intermediate compound in a linear Diels–Alder polyaddition of bismaleimides with bis(2-pyrone)s

The tetrafunctional products 3 and 6 were synthesized via Diels-Alder reaction of bis(2-pyrone) with bismaleimides in mol ratio 1:7. The chemical structure of these products was determined by ¹H-NMR spectroscopy; the high degree of purity was confirmed by means of elemental analysis. The cyclization of the tetraimide 3 with 2 mol monopyrone 7 to the bicycle 8 was carried out. © 1995 John Wiley & Sons, Inc.     

Darstellung,Isolierung und Charakterisierung gemischter Thiocyanato(ethylendiamin)rhodium(III)-Komplexe

Preparation, Isolation, and Characterization of Mixed Thiocyanato(ethylenediamine)rhodium(III) Complexes The complexes Na[Rh(SCN)₄(en)] and trans-[Rh(SCN)₂(en)₂]SCN are prepared for the first time. They are isolated from the mixture by column chromatography on aluminia and characterized by the spectra and the CHN analysis.