Article pubs.acs.org/crystal
Encapsulation and Sensitization of Ln3+ within Indium Metal− Organic Frameworks for Ratiometric Eu3+ Sensing and Linear Dependence of White-Light Emission Xi Du, Ruiqing Fan,* Liangsheng Qiang, Ping Wang, Yang Song, Kai Xing, Xubin Zheng, and Yulin Yang* MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, P. R. of China S Supporting Information *
ABSTRACT: Four novel compounds {[In(FDA)(HFDA)(H2O)4]·2H2O} (In1) and {[Ln2(FDA)2(H2O)10]·FDA· 6H2O}n (Ln = Dy2, Eu3, Gd4) have been hydrothermally synthesized by using the ligand furan-2,5-dicarboxylic acid (H2FDA). Driven by hydrogen bonding and π···π stacking, In1 displays a supramolecular metal−organic framework (MOF) with 6-connected pcu topology. Isostructural Dy2, Eu3, and Gd4 possess one-dimensional “wave-like” chains and further exhibit bnn topological structures with the Schläfli symbol of (46·64) via a hydrogen bonding network. The triplet state (T1 = 22371 cm−1) of H2FAD studied by compound Gd4 indicates that the energy transition from the H2FDA ligand to the Eu3+ ion in compound Eu3 is efficient but inefficient to the Dy3+ ion in compound Dy2. Interestingly, the uncoordinated carbonyl group of compound In1 can sensitize Ln3+ ions to obtain Dy3+@In1 and Eu3+@In1 materials for enhancing luminescence. The possible sensitization mechanism is studied by X-ray photoelectron spectroscopy and surface photovoltage spectroscopy. When the Eu3+ ion is increased from 0.0 to 1.6 μM in aqueous solution, compound In1 exhibits a distinguishable luminescence color change from blue to red with a fast detection time (
