MOF-1115

Paper: Rare Earth pcu Metal–Organic Framework Platform Based on RE₄(μ₃-OH)₄(COO)₆²⁺ Clusters: Rational Design, Directed Synthesis, and Deliberate Tuning of Excitation Wavelengths

Authors: T.-Y. Luo, C. Liu, S. V. Eliseeva, P. F. Muldoon, S. Petoud, and N. L. Rosi

Citation: J. Am. Chem. Soc., 2017, 139, 9333–9340

DOI: 10.1021/jacs.7b04532

Abstract: The T_d point group symmetry of rare earth (RE³⁺) metal clusters RE₄(μ₃-OH)₄(COO)₆²⁺ makes them attractive building blocks for creating metal–organic frameworks (MOFs) with controllable topologies. Herein, we describe the design and synthesis of a series of isoreticular MOFs featuring pcu topology [MOF-1114(RE) and MOF-1115(RE)] with variable rare earth metal ions (RE³⁺ = Y³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺) and linear amino-functionalized dicarboxylate linkers of different lengths. In total, we report 22 MOFs that vary in both composition and structure yet share the same RE₄(μ₃-OH)₄ cluster motif. We demonstrate that these pcuMOFs are cationic and that anion exchange can be used to affect the MOF properties. We also investigate the luminescence properties of a representative member of this MOF series [MOF-1114(Yb)] that exhibits near-infrared emission. We show that the excitation energy for Yb³⁺sensitization can be carefully adjusted to lower energy via covalent postsynthetic modification at the amino group sites within the MOF.