Über das Fluoreszenzthermochrome Acetonitrilo-Kupferjodid mit Dibenzo-18-Krone-6

About the Fluorescence Thermochromism of Acetonitrile Copper Iodide with Dibenzo-18-Crown-6 Copper iodide reacts in actonitrile solution with dibenzo-18-crown-6 to form a compound,(CuJ)₄(CH₃CN)₄(db-18-c-6), which fluoresces yellow at 298K, but pink at 77 K. It decomposes at 55.3°C. (5 Torr) by lost of acetonitrile and a heterogeneous mixture of copper iodide and polyether results. In absence of dibenzo-18-crown-6, copper iodide forms with acetonitrile a heterogeneous mixture of copper iodide and polyether results. In absence of dibenzo-18-crown-6, copper iodide forms with acetonitrile a solvate CuJ. CH₃CN. It also shows fluorescence thermochromism (yellow at 298 K, but green at 77 k) but decomposes at 0°C and 760 Torr. The luminescences pectra of the macrocyclic polyether complex at 298 K is redshifted. This probably results from intersection between the crown and the acetonitrile copper iodide.     

Mass spectral study on thiazolo[3,2-a]benzimidazoles. Studies on heterocyclic compounds. IV

Condensation of α-halocarbonyl compounds and 2-mercaptobenzimidazole gives thiazolo-[3,2-a]benzimidazoles. This condensation occurred at the mercapto group of the benzimidazole followed by cyclization to form the thiazole ring. This was confirmed by the examination of the mass spectra of 2- and 3-methylthiazolo[3,2-a]benzimidazoles, 2- and 3-phenylthiazolo[3,2-a]-benzimidazoles, and their derivatives.     

Bestimmung von Arsen mittels Atomabsorption

Zusammenfassung Arsen wird mittels Atomabsorptionsspektrometrie bei den Wellenlängen 1890,4 Å und 1972,6 Å bestimmt. Als Absorptionsküvette wird ein Graphitrohr in einer Argonkammer verwendet. Um die in diesem Wellenlängenbereich auftretenden Störungen bei der Absorptionsmessung zu vermindern, wird eine Bezugsintensität bei einer benachbarten Wellenlänge mitgemessen. Dadurch ist es möglich, Arsen in Lösungen in einer Menge bis zu 1 ng oder in einer Konzentration bis zu 0,1 g/ml zu bestimmen.

---

Summary Arsenic has been determined with atomic-absorption spectrometry at the wavelengths 1890,4 and 1972,6 Å. A graphite tube in an argon chamber was used as an absorption cell. In order to diminish the fluctuations in absorption measurements in this wavelength region a control intensity was measured at a neighbouring wavelength. By this method it was possible to determine arsenic in a solution in quantities down to 1 ng or in concentrations down to 0.1 g/ml.

---

---

Herrn Prof. Dr. H.Kaiser zum 60. Geburtstag gewidmet.

---

Meiner Mitarbeiterin FräuleinErika Schackmann danke ich für sorgfältige Messungen und manche Anregung.