Functionalized photochromic compounds and their applications in chemical and physical switching processes are under investigation. In this report exclusive consideration is given to the dihydroazulene @HA)/vinylheptafulvene (VHF) system½.A short description of the photochromism of½.is presented. Three topics of potential switching behaviour released by the photochromism of½.are pointed out: (i) change of the pkaand of proton transfer properties in anilinium derivatives, (ii) change of the redox potential in compounds with electron transfer active subunits, (iii) increase of second‐order nonlinear optical properties by irradiation of1.