“…For instance, phenolphthalein changes from colorless to a pale pink colored substance when altering pH of the medium. The main halochromic compounds classes are: phthalides, [6] coumarin, [7] azo dyes, [8] and Imidazole derivatives [9,10] etc., In particular, the imidazole derivatives have been shown as impressive fluorophores due to their larger π-conjugated structure and acidity nature of the NH-group. These optical properties have been exploited in different applications like photographic materials, luminescent materials, two-photon absorption applications, two-photon fluorescence microscopy, high density storage and 3D microfabrication, Non Linear Optics (NLO), Dye Sensitized Solar Cells (DSSC), Organic Light Emitting Diodes (OLEDs) and molecular switches, etc., [11][12][13] The well-known 4-(4,5-diphenyl-1H-imidazol-2-yl)benzaldehyde (DPI-BA) ( Figure 1) has been condensed with various functional groups to make a different push-pull chromophore motifs such as D-π-A, D-π-D or A'-π-A, Y-shaped so on.…”