Development of novel Donor-Acceptor Stenhouse Adducts with Unique Structures and Interesting Photochromic Properties

Donor-Acceptor Stenhouse Adduct (DASA) photo-switches have generated a lot of interest since they were first reported; various areas of research have taken advantage of simple synthesis and the desirable photochromic properties in designing novel systems with interesting applications. The work presented here describes the design and synthesis of novel DASA molecules and an analysis of their photochromic properties. The new systems present a unique structure that causes changes in the conformation of the cyclized DASA form due to an unreacted amino functionality. In addition, the photo-switching properties do not suffer from the concentration limitations exhibited by previously reported DASAs. UV-Vis spectroscopy is used to analyse the photo-switching properties of the DASAs and illustrate impressive switching efficiency, exhibiting >95% loss of absorption upon irradiation. The structure-property relationship is examined through single crystal X-ray diffraction data and computational modelling which reveal changes in the proton transfer steps of the photo-switching mechanism that could to explain the improved switching properties observed. A first look into the solid-state photoswitching potential of DASA molecules is also investigated with preliminary results discussed.