Comparison of the present work with other previous works for Cu²⁺ detection.

Probe structure	Solvent system (v/v)	Detection limit (M)	Time	pH	Application	Mechanism	Ref.
	CH3CN/HEPES = 1/1	5.8 × 10−8	1 h	3–8	MCF-7 cells	The chelation-controlled C N isomerization in anhydrous acetonitrile and Cu2+-promoted cyclization reaction in aqueous acetonitrile	32
	CH3CN/HEPES = 1/9	2.19 × 10−7	11 min	7.0	HepG2 cells	Molecular conjugation enlarged after coordination with Cu2+ ions	33
	CH3CN/HEPES = 4/1	3.30 × 10−5	—	4–9	HepG2 cells	ICT	34
	DMSO/Tris = 1/1	2.14 × 10−8	—	4–11	PC-12 cells	ICT	35
	CH3CN/HEPES = 1/1	3.54 × 10−8	30 min	5–9	Hela cells	Carbon–oxygen bonds break, identification groups fall off, probe fluorescence recovery	36
	EtOH/H2O = 9/1	2.81 × 10−6	—	—	Water samples	ESIPT	37
	CH3CN/HEPES = 4/1	3.20 × 10−7	20 min	2–12	293 T cells	Carbon–oxygen bonds break, identification groups fall off, probe fluorescence recovery	38
	DMSO/HEPES = 1/9	4.55 × 10−8	2 min	6–8	Hela cells	ESDPT	This work