Emission-titration studies of the adduct formation between achiral europium(III)β-diketonates and substrates

Abstract

Emission-titration spectroscopy has been used to study the formation of five europium(III)β-diketonate complexes with NRH₂(R = Prⁿ, Prⁱ, Buⁿ, Bu⁸, or Bu^t) and R′OH (R′= Me, Et, Prⁿ, Prⁱ, Buⁿ, Bu⁸, or Bu^t). The emission intensity of the ⁵D₀→⁷F₂ Eu³⁺ transition is found to be quite sensitive to the interaction between the chelate complex and a substrate molecule. Emission titrations and also Job's method of continuous variations have been used to find both the formation constant and stoicheiometry of all adducts studied. Depending on the chelate complex and substrate, either a 1 : 1 or a 1 : 2 chelate complex–substrate adduct is formed. Steric factors usually play only a minor role in this interaction, although in a few cases they influence the extent of the interaction.