Hydrothermal synthesis, crystal structure, and photoluminescence of novel lanthanide metal organic frameworks constructed from 1,4-benzene-dicarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid as ligands

Abstract

By using 1,4-benzene-dicarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid as mixed-linkers, three novel 3D lanthanide coordination polymers, [Ln(BDC)0.5(BTEC)0.5(H2O)] (Ln = Eu (1) and Gd (2)) and [Tb(BDC)0.5(BTEC)0.5(H2O)] (3) (H2BDC = 1,4-benzene-dicarboxylic acid, H4BTEC = 1,2,4,5-benzenetetracarboxylic acid) were synthesized via hydrothermal reaction. The X-ray single crystal analyses reveal that the three coordination polymers present two types of different crystal cell parameters and hereby exhibited two kinds of different metal–organic frameworks, although they have the similar chemical formula [Ln(BDC)0.5(BTEC)0.5(H2O)]. Of these complexes, complexes 1 and 2 are isomorphous, crystallizing in monoclinic, space group P21/n. While 3 is a 3D eight-coordinated terbium complex with triclinic crystal system and P-1 space group. The occurrence of the different structures of these complexes under the similar preparation method may be related to the lanthanide contraction effect. Additional, the thermogravimetric analyses and photoluminescent properties for complexes 1 and 3 were discussed in detail. Three novel coordination polymers, [Ln(BDC)0.5(BTEC)0.5(H2O)] (Ln = Eu (1) and Gd (2)) and [Tb(BDC)0.5(BTEC)0.5(H2O)] (3) (H2BDC = 1,4-benzene-dicarboxylic acid, H4BTEC = 1,2,4,5-benzenetetracarboxylic acid) have been firstly synthesized hydrothermally. Complexes 1 and 2 are isomorphous, crystallizing in monoclinic, space group P21/n. While 3 is a novel eight-coordinated Tb(III) complex with triclinic crystal system and P-1 space group.