Rational Construction of Two Zn–Organic Frameworks for Selective Luminescent Sensing and Efficient CO2 Chemical Fixation

Through a hydrothermal reaction of 3-(3-carboxylphenyl) isonicotinic acid (H2L) and dipyridyl with Zn(Ac)2·2H2O, two metal–organic frameworks (MOFs), [Zn(L)(bpa)0.5]n (1) and {[Zn(L)(bpp)0.5]·H2O}n (2) (bpa = 1,2-bi(4-pyridyl)ethane, bpp = 1,3-di(4-pyridyl)propane), are prepared. Complexes 1 and 2 have similar twofold interpenetrated three-dimensional (3D) layer-pillared networks. Compounds 1 and 2 exhibit outstanding fluorescence-sensing performances toward Cr2O72–, especially, featuring the ratiometric fluorescence against levofloxacin (LEVO) and ciprofloxacin (CIP). To the best of our knowledge, it is the first example of ratiometric detection using antibiotics. The quenching mechanism is mainly attributed to the large area of competitive absorption between the ultraviolet (UV) absorption bands of substances and the excitation peaks of complexes. Furthermore, compounds 1 and 2 could serve as efficient heterogeneous catalysts for the fixation of CO2 with various epoxides benefiting from the presence of unsaturated zinc ions as Lewis acid sites.