Synthesis, Crystal Structures and Luminescent Properties of Zn(II)/Cd(II) Metal–Organic Frameworks Constructed by 1,4-Benzenedicarboxylic Acid and 4,4′-(2,5-Difluoro-1,4-phenylene)dipyridine

Two new 3D fluorescence metal–organic frameworks, namely [Zn2(p-bdc)4(dfdp)2]n (1) and [Cd2(p-bdc)4(dfdp)4]n (2) (p-H2bdc = 1,4-benzenedicarboxylic acid; dfdp = 4,4′-(2,5-difluoro-1,4-phenylene)dipyridine) have been synthesized under solvothermal conditions and structurally characterized by elemental analysis, infrared spectra, TG, UV–Vis spectra, fluorescence spectra, single crystal and powder X-ray diffraction. Compound 1 shows a 3D framework constructed by infinite [Zn2(p-bdc)4]n layer as nodes and the dfdp ligands as connected linkers. Compound 2 reveals a different structure from compound 1 which can be mainly attributed to different coordination numbers of dfdp linkers. Compared with compound 2, UV–vis spectrum of compound 1 is 25 nm red-shifted. Both compounds show strong solid-state luminescence at about 400 nm. Of particular interest is that the quantum yield of compound 1 is 11.73. Two novel 3D fluorescence metal–organic frameworks [Zn2(p-bdc)4(dfdp)2]n (1) and [Cd2(p-bdc)4(dfdp)4]n (2) have been synthesized and structurally characterized. Compound 1 show strong solid-state purple luminescence with 11.73 quantum yield (QY).