A 1, 8-naphthyridine modified rhodamine B derivative (1) has been designed and synthesized. Compound 1 is the first 1, 8-naphthyridine-modified rhodamine B sensor that can detect Cu2+ selectively with a dramatic color change from colorless to pink. The complex of 1 and Cu2+ was utilized as a chemosensing ensemble for cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) detection, which showed highly sensitive and ...