Fig. 4. Time-dependent difference spectra of electrochemically oxidised (a) Et₄L¹ and (b) thin film of MFM-186 in CH₂Cl₂ containing [ⁿBu₄N][BF₄] (0.4 M). The background noise observed here is relatively high as a result of low quantities of MFM-186 being deposited and the discontinuous nature of the MOF film. Potentials are reported vs. Fc⁺/Fc. Kohn–Sham frontier orbital (HOMO) of (c) Et₄L¹ and (d) model system for MFM-186. Colour code: C: dark grey, H: light grey, Cu: blue, O: red, HOMO: green and yellow.