Enhanced near-infrared-luminescence in an erbium tetrafluoroterephthalate framework

Two erbium - organic frameworks Er-2( BDC)(3)( DMF)(2)( H2O)(2)center dot H2O ( 1) and Er-2( BDC-F-4)(3)( DMF)( H2O)center dot 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 Er-2( BDC)(3) ( 1a) and partially desolvated solid Er-2( BDC-F-4)(3)( DMF)center dot 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.