Acid-induced Zn(ii)-based metal–organic frameworks for encapsulation and sensitization of lanthanide cations

Abstract

Two Zn(II)-based metal–organic frameworks, namely, [Zn₃(Hbptc)₂(DMF)₂]·2DMF(1) and [Zn₅(bptc)₃(H₂O)]((CH₃)₂NH₂)₂(2), (H₄bptc = 3,3′,5,5′-biphenyltetracarboxylic acid, DMF = N,N′-dimethylformamide), have been synthesized using different amounts of nitric acid under mixed-solvothermal conditions. 1 and 2 display different coordination geometries and donor ligands for the Zn²⁺ ions. In 1, only three carboxylic acid groups of H₄bptc take part in the construction of the three-dimensional (3-D) framework with Zn²⁺, and one remains uncoordinated that can bind to other metal ions. Postsynthetic exchange of 1 with Ln³⁺ cations demonstrates that 1 can effectively capture metal cations and sensitize the visible-emitting Ln³⁺.