Recent Development of Dihydroazulene-based Molecular Switches

In recent years, the 1,1-dicyano-dihydroazulene/vinylheptafulvene (DHA/VHF) molecular switch has been considered a qualified candidate for solar energy storage in closed-cycle systems and the research has been directed towards tuning its energy storage capacity and developing different ways to trigger the energy release upon demand, possibly allowing recyclability of the system. The core of the parent DHA is attractive because the multiple positions available for functionalization can generate diversity in terms of optical and switching properties of the photochromic system, and making it appealing for a wide range of applications, from smart materials, to photo-responsive biological systems, to sensing. In the present communication, we will give a general overview of the recent advances and the multiple approaches undertaken to fully exploit the potential of this photochromic system, included the effects exerted by the introduction in macrocyclic systems.