Notably, using this experimental set-up, the reaction reached completion for all three PCs in less than 3 hours, significantly faster than using a photoreactor, presumably due to more efficient irradiation within the in situ NMR set-up. Furthermore, when catalysed by Mes3DiKTa or DiKTa the rate of product formation is significantly enhanced than with 4CzIPN. To quantify these differences, initial rates of the reaction with each photocatalyst were calculated and compared, with the use of DiKTa giving a slightly larger initial rate (5 x 10 -4 M s -1 ) than Mes3DiKTa (3.7 x 10 -4 M s -1 ), but with both an order of magnitude larger than that of 4CzIPN (0.6 x 10 -4 M s -1 ) (Table ).