First stable (Z)-configuration of cyanostilbene derivative: An effective “turn-on“ fluorescent sensor for lysine in aqueous media

•The first stable (Z)-configuration of cyanostilbene derivative ((Z)-CS) was prepared.•(Z)-CS exhibited selective sensing abilities for lysine among all kinds of species.•(Z)-CS showed the strong “turn-on” fluorescence after sensing lysine.•The detection limit of (Z)-CS for lysine attained 1.34 × 10−7 M.•(Z)-CS displayed good bioimaging performance for detecting lysine in living system.