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 Cr2O7
2–, 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.