Informed by the absorption profile of the reagents and additives (Figure ), the excitation wavelength was changed from 390 nm to 427 nm, since the former is capable of photoexciting both pDTCz-DPmS and HE, while the latter allows selective photoexcitation of HE only. Not surprisingly, both in the presence and absence of pDTCz-DPmS at 427 nm excitation, comparable yields were obtained of 53% and 48%, respectively (entries 9 and 10), that are akin to that of the background reaction (entry 5). a Reaction conditions conducted as shown in Figure unless otherwise noted. For further details consult the SI. 1 H NMR yields obtained from at least two independent runs with the standard deviation given using 1,3,5-trimethoxybenzene as an internal standard. b No light.