Phenanthrolines polarography

Phenanthroline reacts with trimethyloxonium fluoroborate in ethylene chloride solution to give the 2,7-dimethyl diquaternary salt.15,307 From polarography experiments it was shown to be reduced by a one-electron transfer to the corresponding radical cation. The reduction potential is lower than that of diquaternary salts of 1,10-phen-anthroline, an E0 value of —0.33 volt being recorded in aqueous solution. 

Phenanthrolines (84) are obtained by photochemical cyclization of 1,2-dipyridyl ethylenes (85). Their bisquaternary salts (86) are obtained by polarography of the corresponding pyridinium salts... 

An outstanding example is the prewave of Eu(III)-o-phenanthroline (Osipova, 1981) in ac polarography. In the base electrolyte NH Ac at pH 6-7, the reduction of Eu to Eu " with a peak potential equal to —1.09 V SCE is irreversible. On addition of a small amount of phenanthroline, a prewave at = — 0.81 V SCE is observed, the height of which is proportional to concentration in the range 1 X 10 to 1 X 10 M Eu. Pr, Nd, Sm, Gd, Tb, Y and La do not interfere. This method was applied to determine the Eu content in europium-doped ytterbium oxysulfide, which is a cathodoluminophor. This catalytic prewave is produced by a heterogeneous reaction between Eu + and o-phenanthroline on the electrode surface. 

X-phenanthroline (in buffered AcOH) detn. of complex formation and equil. const, by polarography, ion exchange and potentiometry X H, Me, Cl... 

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