Estudios fotoquímicos y electroquímicos de complejos lantánidos de 6-(hidroximetil)piridin- 2-carboxaldehído[2- metilpirimidina-4,6-diil] bishidrazona

Abstract

<p>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 1 H 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 (III) 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.</p>