Post-modification Of A MOF Through A Fluorescent-labeling Technology For Sensing And Adsorption

Luminescent MOFs are very promising multifunctional materials for chemical sensors, light-emitting devices, and biomedicine. As MOFs have a degree of structural predictability and the well-defined environments for luminophores in crystalline forms, they offer unique platform for the development of solid-state luminescent materials. Generally, luminescence can arise from organic ligands, metals, and guest molecules. However, the incorporation of fluorescent dyes within the stable pores of MOFs is still a big challenge, because most of the bright luminophores are not compatible with the MOF synthetic conditions or exhibiting groups interfere with the formation of the desired MOFs. Inspired from fluorescent labeling technology, the common labeling dye, Fluorescein Isothiocyanate (FITC), was selected to post-modify MOFs self-assembled by neutral ligands or acidic ligands. The application of modified MOFs in metal-ions detection and adsorption was also investigatedA new metal-organic framework (BTPY-NH2) with amino groups and neutral ligands was obtained. Single-crystal X-ray diffraction revealed that the largest pore and window sizes of BTPY-NH2were about27A and14A in diameter respectively, the solvent accessible volume accounted for81.2%of the crystal volume. After post modification of BTPY-NH2with fluoresceinisothiocyanate (FITC), FITC@BTPY-NH2was obtained, the wt%of FITC was measured about5-10%. Through studying the recognition ability and adsorption of FITC@BTPY-NH2for metal ions, it indicated that modified MOF can sense Ag+in aqueous solution selectively.The detection limit was0.1ppm.Reported metal-organic frameworks:NH2-MIL-125(Ti) and UMCM-1-NH2based on2-aminoterephthalic acid were selected. The window sizes of them were about5A and12A in diameter respectively. After modified by FITC, the FITC contents in both MOFs were measured about wt%=1.4%and29%respectively. Furthermore, the recognition ability of FITC@NH2-MIL-125(Ti) for metal ions was studied. It showed that the modified MOF can detect sensentively Ag+and Hg2+in aqueous solution. The detection limits of Ag+and Hg2+were1.3ppm and0.3ppm respectively.