Three metal–organic frameworks (MOFs) comprising micropore, mesocage and nanotube structures have been prepared based on the same ligands and binuclear zinc secondary building units. We have successfully achieved flexible modulation of pore size from micropore to mesopore in a binary system by adjusting the reactant ratio. With the merit of a nanoscale channel, IFMC-8 can be applied as the host material for encapsulating Alq3 chromophores to exhibit tunable luminescence. The fluorescence emission of composite material Alq3@IFMC-8 has changed from green to blue. More importantly, the inclusion of IFMC-8 effectively prolonged the excited-state lifetime of Alq3 in ethanol. To the best of our knowledge, it is the first time that a MOF was studied as the host material for modulating the fluorescence properties of Alq3 chromophores.