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)center dot 2H(2)O, two metal-organic frameworks (MOFs), [Zn(L)(bpa)(0.5)](n) (1) and {[Zn(L)(bpp)0.5]center dot 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.

Automated summary

Two metal-organic frameworks (MOFs) were prepared through a hydrothermal reaction. These MOFs exhibited excellent fluorescence-sensing performances towards Cr2O72- and were used for ratiometric detection using antibiotics for the first time. Furthermore, they served as efficient heterogeneous catalysts for the fixation of CO2 with various epoxides.