Novel photofunctional hybrid materials (alumina and titania) functionalized with both MOF and lanthanide complexes through coordination bonds

Abstract

In this paper, series of luminescent hybrid materials (alumina, titania) functionalized with both lanthanide complexes and metal organic frameworks (MOF, Al-MIL-53-COOH) through coordination bonds. In these hybrid systems, both MOF and lanthanide (Eu³⁺, Tb³⁺) complexes with beta-diketonates (2-thenoyltrifluoroacetonate (TTA), 1,1,1-trifluoroacetylacetone (TAA), 2,4-pentanedionate (AA)) and pyridine-3,5-dicarboxylic acid (PDA) are coordinated to alumina and titania through their carboxylic groups. Al-MIL-53-COOH possesses the active –COOH group and can be linked to metallic alkoxides (Ti[OCH(CH₃)₂]₄ and Al[OCH(CH₃)₂]₃), by a post-synthesis path. Ternary complexes of beta-diketonates and PDA can be further bonded with metallic alkoxides through PDA as a bridge for its carboxylic group coordination. After hydrolysis and a condensation process, the final multi-component hybrid materials can be assembled and characterized. The photophysical properties of these hybrid materials were studied in detail, and their luminescent color can be tuned by controlling the composition of different units in the hybrid system. Especially with the hybrids of europium complexes and MOF, the white luminescence can be obtained by integrating the emission of both europium complex and MOF. Furthermore, the luminescent films that were prepared show both uniformity and transparency. These results provide some useful data for the multi-component assembly and luminescent integration of photofunctional hybrid materials based on MOF and lanthanide units, which can be expected to have some potential applications in luminescent devices for display or lighting.