Abstract

FERNANDEZ, Mara Alejandra; BARONA, Juan Camilo; POLO-CERON, Dorian  and  CHAUR, Manuel N. Photochemical and electrochemical studies on lanthanide complexes of 6-(hydroxymethyl) pyridine-2-carboxaldehyde[2-methyl-pyrimidine-4,6-diyl]bis-hydrazone. Rev.Colomb.Quim. [online]. 2014, vol.43, n.1, pp.5-11. ISSN 0120-2804.  https://doi.org/10.15446/rev.colomb.quim.v43n1.50540.

Herein we report the synthesis of the 6-(hydroxymethyl)pyridine-2-carboxaldehyde[2-methyl-pyrimidine-4,6-diyl]bis-hydrazone by a condensation reaction between 6-(hydroxymethyl)picolinaldehyde with 4,6-(bis-hydrazino)-2-methylpyrimidine. This bis-hydrazone can be visualized as a two-arm system which exhibits photochemical induced [E,E]/[E,Z]/[Z,Z’] isomerizations and double coordination to metal centers. Configurational changes, upon UV light irradiation, were followed over time by ¹H NMR, establishing that isomerization, in both arms, is a consecutive reaction that follows first-order kinetics (k1= 4.06 x 10^-4 s^-1 and k2= 2.80 x 10^-4 s^-1). Furthermore, the synthesis of bis-hydrazone metal complexes with La and Sm (III) ions was achieved; subsequently, the absorption and emission properties of these complexes were studied, determining the fluorescence quantum yields, ΦLa= 0.2024 and ΦSm= 0.1413. Electrochemical studies of the complexes were conducted by square wave voltammetry, demonstrating that the bis-hydrazone and its complexes are electroactive species between +1.5 and -2.5 V.

Keywords : Lanthanide complexes; photochemistry; bis-hidrazones; isomerization; UV-Vis/Fluorescence; electrochemistry.

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