Binding constants (K_asoc, M⁻¹)^a calculated for 3 and the sodium salts of anionic analytes in 15% water in DMSO.

Anion	K asoc	Quench (%)	FWHM (nm)	Shift (nm)
F−	NDb	5	119	0
Cl−	<10	6	113	6
Br−	<10	3	113	0
NO3−	NR	+2	120	0
HSO4−	NR	0	118	0
CH3CO2−	<100b	+7	115	12
H2PO4−	1.65 × 106	18	113	14
H2P2O72−	5.82 × 105	24	113	14
HAsO42−	3.55 × 106	25	116	12
AMP	1.61 × 105	12	111	18
ADP	<100c	9	117	6
ATP	<100c	7	120	6
GlyP	2.70 × 105	12	119	9
MPA	8.20 × 104	8	115	10
PhPA	<100	0	116	14
EMPA	<100	+2	119	6

^aThe K_asoc values were calculated based on the change in fluorescence intensity upon an incremental addition of each anion (sodium salts in water). All fitting errors were <15%. λ_exc = 370 nm. The association constants were calculated using non-linear least-square fitting. NR – no appreciable response was observed.

^bND – not determined due to what appears to be a partial deprotonation of the sensor and the ensuing complex equilibria.

^c K _asoc was not determined due to the biphasic nature of the isotherm.