Enhanced near-infrared-luminescence in an erbium tetrafluoroterephthalate framework.

Two erbium-organic frameworks Er2(BDC)3(DMF)2(H2O)2.H2O (1) and Er2(BDC-F4)3(DMF)(H2O).DMF (2) (BDC = 1,4-benzenedicarboxylate; BDC-F(4) = 2,3,5,6-tetrafluoro-1,4-benzenedicarboxylate or tetrafluoroterephthalate; DMF = dimethylformamide) have been synthesized and structurally characterized. Studies on thermal gravimetric analysis and the spectroscopic and luminescent properties of 1, 2, and their desolvated solid Er2(BDC)3 (1a) and partially desolvated solid Er2(BDC-F4)3(DMF).DMF (2a) indicate that fluorination can significantly improve the luminescence intensity of the Er ions by reducing the fluorescence quenching effect of the vibrational C-H bond; thus, the near-IR-luminescence intensity of 2a is 3 times higher than that of 1a.