Photo-/Baso-Chromisms and the Application of a Dual-Addressable Molecular Switch.

Two typical molecular switches of spiropyran (SP) and benzoxazine (OX) were fused by sharing an indole to achieve a new dual-addressable molecular switch (SP-OX-NO2 ). Through proper molecular modification with NO2 , the transformation from merocyanine (MC) to ring-closed SP or ring-closed OX can be controlled separately with visible light or base stimuli in solution, respectively, and these processes are verified by UV-vis and NMR spectroscopy as well as control experiments. The cis-merocyanine (cis-MC) form is involved in the basochromic process in solution. DFT calculation suggests that the bidirectional switching property of the fused SP-OX molecular switch can be controlled separately, when the OX isomer is more stable than the deprotonated SP isomer. Because of the significant color variations in solution, the simple dual-addressable switch has been further successfully applied to construct a multicolor reversible display on paper.