Fe(II) coordination complexes have been anchored on robust metal–organic framework secondary building units using a sequential installation strategy. The coordination sphere around Fe(II) was modulated upon sorption of alcohols in the pores of the MOF, leading to a reversible colour change from orange to red. In the case of MFU-4l, a preferential adsorption of MeOH has been observed, evidencing the fact that the host matrix can be used for pre-concentrating a targeted analyte, which may be beneficial for the design of sensing devices.