Lanthanide-2,3,5,6-Tetrabromoterephthalic Acid Metal–Organic Frameworks: Evolution of Halogen···Halogen Interactions across the Lanthanide Series and Their Potential as Selective Bifunctional Sensors for the Detection of Fe3+, Cu2+, and Nitroaromatics

Abstract

Two series of lanthanide metal–organic frameworks (MOFs) formulated as {Ln2(TBrTA)3(H2O)8·2H2O}n [Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6), Gd (7), Tb (8), Dy (9)] series 1, {[Ln3(TBrTA)6][Ln(H2O)8]·6H2O}n [Ln = Ho (10), Er (11), Tm (12), Yb (13), Lu (14)] series 2, respectively, were synthesized via slow evaporation with tetrabromoterephthalic acid (H2TBrTA) and structurally characterized by X-ray crystallography, infrared spectroscopy, and thermal analysis. Lanthanide contraction effects result in a change in the structure from a two-dimensional (2D) MOF with sql topology for La–Dy (series 1) to a three-dimensional (3D) MOF with pcu network topology for Ho–Lu (series 2). Supramolecular interactions also evolve from Br···Br, Br···O, π–π, and hydrogen bonding interactions in series 1 to Br···Br and hydrogen bonding interactions in series 2. The nature of Br···Br interactions transition from a combination of type I, type II, and quasi-type I/type II in series 1 to only type II in series 2. Furth...