Regardless the solvent, the absorption spectra of the oxo-photoswitches bearing a hydroxy or alkoxy donor group (compounds 4a-c) show three broad peaks centered around 290, 320, and 370 nm, similar to those of natural CC. A bathochromic shift is observed for the amino compound 4d with bands centered around 320 and 390 nm. This shift can be explained by the more pronounced donor capability of amine with respect to hydroxy or alkoxy moieties. Due to the acceptor modification and the corresponding increase of π conjugation, malonitrile derivatives 6a-d present absorption bands at higher wavelength in all the solvents, peaking around 290 and 410-440 nm (Figure and S1, Tables and). In addition, a bathochromic shift in both absorption and emission is observed when increasing the solvent polarity.