Fig. 1: Different scenarios in photochromic properties of multiple diarylethene-containing systems.
a Partial photochromic reaction: the system showing a single photochromic reaction due to the quenching process which prohibits the second photochromic reaction. b Simultaneous photochromic reactions: the system displaying multiple photochromic reactions at the same time to result in a single photoinduced color change. c Stepwise photochromic reactions via nonselective photocyclization reactions: the system showing simultaneous photocyclization reactions, followed by selective photocycloreversion reactions of individual photogenerated closed forms upon photoexcitation at specific wavelengths. d Stepwise photochromic reactions via selective photocyclization reaction: the system in this work featuring an exclusive photocyclization reaction of the visible-light-driven photoswitch, followed by a subsequent photocyclization reaction of the UV-driven photoswitch, and the selective photocycloreversion reactions of their closed forms by photoexcitation at different wavelengths. PA and PB denote photoswitches A and B, respectively, and (o) and (c) denote open and closed forms, respectively.
