Structural variations and photoluminescent properties of a series of metal-organic frameworks constructed from 5-(4-carboxybenzoylamino)-isophthalic acid

Abstract

Five new metal-organic frameworks (MOFs) with 5-(4-carboxybenzoylamino)-isophthalic acid (H 3 L), namely, [Cd 9 L 6 (DMA) 6 ]·4DMA ( 1 ), [Cd 3 L 2 (H 2 O) 9 ]·4H 2 O ( 2 ), [LaL(H 2 O) 4 ]·2H 2 O ( 3 ), [CeL(H 2 O) 4 ]·H 2 O ( 4 ) and [Tb(HL)(H 2 L)(H 2 O) 3 ]·5H 2 O ( 5 ) (DMA=N,N-dimethylacetamide), have been synthesized. Complex 1 shows a three-dimensional architecture generated from linkage of Cd–O chains via L 3− ligands. Minor variations in synthetic conditions of 1 afforded 2 , which features an interesting 2D→3D catenation architecture containing helical chains. Complexes 3 and 4 are isostructural and each feature a two-dimensional architecture constructed from the linkage of L 3− with Ln 3+ . Complex 5 displays a chain-like structure, of which the most interesting feature is the existence of free carboxylic acid (–COOH) group which may confer unique functionality. Moreover, the investigations of the thermal stability, powder X-ray diffractions and solid-state photoluminescent properties for these crystalline materials have been carried out. Solvothermal reactions of tricarboxylate ligand H 3 L with Cd 2+ /Ln 3+ has yielded a series of new MOFs containing interesting structural motifs. • A tricarboxylate ligand whose coordinating functionalities are not symmetry equivalent is employed to construct MOFs. • Complex 2 features an interesting 2D→3D catenation architecture containing helical chains. • Complex 3 feature chain-like structure containing free – COOH group, which may confer unique functionality. • Photoluminescent properties and thermal behaviors for 1 – 5 have been reported.