The electrochemical behavior of 2a-c was investigated by cyclic voltammetry in DCM solution (Table and Figs. S14-18). All three compounds display similar reduction processes, with potentials characteristic of the benzophosphole oxide unit: Ered(2a) = -1.59 V vs FeCp*2 +/0 , Ered(2b) = -1.70 V vs FeCp*2 +/0 and Ered(2c) = -1.46 V vs FeCp*2 +/0 . Moreover, 2a and 2b display an irreversible process for the reduction while 2c is showing a quasi-reversible process. Regarding oxidation, all compounds display oxidation waves typical of arylamines. These processes are quasi-reversible for 2a and 2b, and reversible for 2c. All the oxidation waves are doubled in intensity compared to the reductions, due to the presence of two arylamine groups. The values of Eox nicely reflect the electron-donating ability of the different amines: Eox (2a) = +1.06 V vs FeCp*2 +/0 , Eox (2b) = +0.83 V vs FeCp*2 +/0 and Eox (2c) = +0.87 V vs FeCp*2 +/0 . To gain deeper insights into the optical properties of the fluorophores, DFT and TD-DFT calculations were carried out (see the ESI for details). In considering the various systems, a notable difference appears in the absorption. Indeed, while for 2a, and 2b, TD-DFT returns a strongly dipole-allowed first transition with respective f larger than 0.400, the two first excitations of 2c show very weak oscillator strengths of 0.027 and 0.017, and it is only the third transition that develops a sizeable f (0.317) in that compound. The computed vertical absorptions for the first transition are 402 and 415, for 2a and 2b respectively. Although vertical absorption values are not max, 14 one can see a reasonable qualitative match between experiment and theory in terms of position of the first strong absorption. For 2c, the two weakly allowed transitions are positioned at 374 and 367 nm, and the main strong band at 324 nm. This is well in line with the experimental finding: a strong absorption between 300 and 350 nm, followed by a long tail at longer wavelengths for 2c (Fig. ).