Synthesis and characterization of new potential tadf photocatalysts

The use of organic dyes in photoredox catalysis represents one of the fields in which photocatalysis must still unfold its potential. In the last 10 years, thanks to the pioneering work of Zeitler and Zhang, donor-acceptor cyanoarenes have emerged as an asset for photoredox catalysis, due to their modular structure which allows the easy tuning of their photoredox properties. In a study on a Ni-catalytic, visible light-promoted C-N cross-coupling, we found that one of the best performing photocatalyst, commercially available 3DPA2FBN, was also producing two by-products, identified by HPLC-MS analysis as deriving, respectively, from loss of one and two HF molecules. In this work, we successfully isolated the two products (1 and 2 in Figure 1) as new potential visible light-absorbing photocatalysts and managed to assess an optimized method to synthesize them. NMR and XRD studies showed that each of these products is obtained as a single regioisomer, whose structure was fully elucidated. The photophysical properties of 1 and 2 were determined by electrochemical and spectroscopic techniques. Their catalytic activity was preliminarily assessed by employing the known protocol for C-N coupling as a benchmark.