Some spectrofluorimetric applications of the cerium(IV)-cerium(III) system

Cerium(III) ions in dilute sulphuric acid medium exhibit a characteristic fluorescence which has its excitation maximum at 260 nm and its fluorescence emission maximum at 350 nm. By utilising the osmium-catalysed redox reaction between cerium(IV) and arsenic(III), microgram amounts of arsenic (7.5–37.5 μg) may be determined by spectrofluorimetric measurement of the ceriurm(III) produced. The principle may be applied to the determination of several other ions which cannot yet be determined by direct spectrofluorimetry, e.g.. Fe(II) (5.6–28 μg), oxalate (8.8–44μg). Osmium(VIII) (0.05–0.2 μg) and iodide (0.6–2.5 μg) may be determined by their catalytic action.     

Heat of formation of yttrium-bismuth alloys

In the Y—Bi system the formation heats were measured using a direct isoperibol calorimeter. The following values were found for the two known compounds:

     

The alkaloids from the fruits of the plant Daphniphyllaceae

Six alkaloids have been isolated from the fruits of the plant Daphniphyllaceae. Two of them are new alkaloids, namely methyl homodaphniphyllate (1) and daphnilactone-B (2). The structure of the former was deduced by chemical transformation from daphniphylline (3). The structure of daphnilactone-B was estimated by the exhaustive spectral analysis as well as by chemical evidences, and finally determined by an X-ray crystallographic analysis of the free base.     

Preparation of trimethylsilyl derivatives of amino acids and peptides for peptide synthesis

Russian Chemical Bulletin -     

Darstellung,Schwingungsspektren und Struktur von Oxotetrafluorovanadaten MIVOF4 (MI = Na,K, Rb,Cs, Tl, (CH3)4N)

Preparation, Vibrational Spectra, and Structure of Oxotetrafluorovanadates M^IVOF₄ (M^I = Na, K, Rb, Cs, Tl, (CH₃)₄N) The compounds M^IVOF₄ (M^I = K, Rb, Cs, Tl) and M^IVOF₄ · H₂O (M^I = Na, (CH₃)₄N) have been prepared. The crystal structure of KVOF₄ has been determined by single crystal X-ray diffraction. The VOF-ions form endless chains by fluorine bridges. The lengths of the bridge bonds are 1.875(7) and 2.333(7) Å. The terminal V? O- and V? F-distances are 1.572(8) and 1.793 Å (mean value), respectively. The vibrational spectra have been registered and assigned.