Switch On/Switch Off Signal in an MOF-Guest Crystalline Device

A metal organic framework (MOF) based on the [Cu(4)I(4)DABCO(2)] cluster (DABCO = 1,4-diazabicyclo[2.2.2]octane), MOF 1, shows bright emission with a maximum at 556 nm and an emission quantum yield of 0.53 in the solid state. When the large cavities of the MOF are loaded during the synthesis with different amounts of ferrocene {FeCp2, [((5)-C5H5)(2)Fe-II]}, the luminescence of MOF 1 decreases with the increase in the ferrocene content, reaching an almost complete quenching for 3.5 wt.-% of cage loading, corresponding to the complete filling of the MOF cavities. When an electric potential is applied to the FeCp2@MOF 1 deposited onto an ITO glass, the (FeCp2)-Cp-II is oxidised to (FeCp2+)-Cp-III, and the MOF 1 emission is partially switched on again, indicating that a photoinduced electron-transfer reaction is contributing to the quenching process.