Next, we investigated the reversibility of the system under both photochemical and thermal (in the dark) conditions. The relative rates of isomerisation under otherwise comparable experimental conditions are summarised in Figure . The initial Z state of the molecule was recovered both under photochemical (λirr = 520 nm) and thermal conditions, although the back-isomerisation is significantly slower under thermal conditions. In fact, the half-lives followed a first-order rate decay, and were 42 s and 5.4 min under photochemical and thermal (in the dark) conditions, respectively. Finally, we examined the photostability of the system over 14 switches between Z and E, by alternately irradiating the system with blue light (λ = 405 nm) and green light (λ = 520 nm). As showing in Figure , the isosbestic points are preserved across throughout the experiment and the respective UV/Visible spectra are perfectly superimposable, indicating no photodecomposition under the reaction conditions. [Ligand] = 100 µM, 100 mM potassium phosphate buffer (pH 7.4).