Design of Enaminitrile Switches with Enhanced Protofluorochromic Properties

Functional switches exhibiting distinct functionalities responding to a specific stimulus are highly desirable for fabricating advanced devices with superior dynamic performances. Herein, a series of enaminitrile switches are explored as protofluorochromic entities by modulation of their structures, assisted by density functional theory calculations. The switches show high stabilities and exhibit reversible E / Z isomerization behavior, along with tunable fluorescence intensity in both protic and aprotic media. Switches based on 2‐pyridyl‐ or 2‐pyridylmethyl‐containing N ‐components exhibit strong fluorescence in their protonated Z ‐configurations, compared to their phenyl/benzyl counterparts. This behavior can be attributed to variations in intramolecular charge transfer or excited‐state intramolecular proton transfer effects. The Z ‐isomers are furthermore studied in their aggregated solid/film/dispersion states, resulting in notable aggregation‐induced emission behavior.