Orthogonal‐ and Path‐Dependent Photo/Acidoswitching in an Eight‐State Dihydroazulene‐Spiropyran Dyad

Molecules comprised of two or more switches have potential to exist in a variety states, which may only be accessible by “correct” sequence stimuli on account the influence neighboring unit. Here we present straightforward synthesis dyad incorporating photoswitchable units, dihydroazulene (DHA) and spiropyran (SP). The photoswitching properties both chromophores acido-triggered switching SP were retained dyad, allowing selective between eight states with distinct absorption fluorescence (corresponding light-controlled on/off switching). Photoisomerization DHA protonation allowed an orthogonal control individual sites. Conversely, photoisomerization its merocyanine (MC) isomer could not performed without also addressing DHA-to-vinylheptafulvene (VHF) switching. Access DHA-MC state thus appeared path-dependent as it exclusively reached deprotonation thermally stable DHA-E-MCH.