Preparation of transparent sol-gel films containing europium, terbium, and ytterbium cations from 4-(3′-triethoxysilylpropylimino)-pent-2-en-2-ol

A reaction of 3-aminopropyl(triethoxy)silane with acetylacetone gave a mixture of two isomeric carbon-functionalized organosilicon compounds capable of complexation and sol-gel polymerization. These were 4-(3′-triethoxysilylpropylimino)-pent-2-en-2-ol (EtO)3Si-CH2CH2CH2-N=C(Me)CH=C(Me)OH (Ia, 83%) and 4-(3′-triethoxysilylpropylamino)-pent-3-en-2-one (EtO)3Si-CH2CH2CH2-NH-C(Me)=CH-C(O)Me (Ib, 17%). With acetylacetone trimethylsilyl ether instead of acetylacetone itself, compound Ia and silylated derivatives (Me3SiO) n (EtO)3 − n Si-CH2CH2CH2-N=C(Me)CH=C(Me)OH were obtained as admixture in 84 and 16% yields, respectively. Reactions of ligands Ia and Ib with europium and terbium propan-2-olates afforded the corresponding complexes. Formulations of lanthanide complexes, oligodimethylsiloxanediols, and 3-aminopropyl(triethoxy)silane were used to prepare transparent sol-gel films. The photoluminescence spectra of the films show narrow bands due to Eu3+ or Tb3+ emission. Emission from the organosilicon matrix appears as a broad band at 430 to 435 nm.