Fortunately, the distinctive features of the spectra observed for 2 and its reduced forms fall within the limits imposed by the FTO glass substrate. Three peaks between 450 nm and 550 nm, corresponding to the neutral state 1, are observed with the relative intensities of the three peaks indicating aggregated PDI groups. The reduction in intensity of these peaks following reduction coincides with the emergence of a new set of peaks at longer wavelengths between 570 nm and 800 nm with λmax around 700 nm. As the experiment progressed, these peaks associated with the first reduced species (2) •-decreased steadily with a concomitant appearance of the absorption bands with λmax of approximately 670 nm, attributable to the second redox state (2) 2-. Comparison of the UV-vis spectra of 2 and solution-phase SEC spectra for L 1 (Figure ) clearly demonstrate the retention of the electrochemical behaviour of the parent PDI linkers in the resulting MOF structures.