Table 1. Photophysical properties of ASiP^a and NIR-ASiP^a analogues.

	R 1 (alkyl)	R 2 (EWG)	λ abs a /nm	λ em b /nm	Φ F c
ASiPa1	Me	H	452	612	0.33 d
ASiPa2	Bn	H	469	623	0.34 e
ASiPa3	Propargyl	H	473	628	0.25 e
NIR-ASiPa1	Me	CO2Bn	669	685	0.42 f
NIR-ASiPa2	Propargyl	COCH3	676	694	0.31 e
NIR-ASiPa3	Propargyl	COCF3	684	707	0.27 e
NIR-ASiPa4	Propargyl	SO2CF3	694	713	0.25 e
NIR-ASiPa5	Bn	COCF3	684	704	0.29 e
NIR-ASiPa6	Cyclic urea		674	690	0.22 e

^aMaximum absorption wavelength.

^bMaximum emission wavelength in PBS (pH 7.4).

^cFluorescence quantum yield.

^dDetermined in methanol using fluorescein as the reference (Φ_F = 0.95 in 0.1 M NaOH).18

^eDetermined in ethanol using rhodamine 101 (Φ_F = 0.915 in EtOH) as the reference dye.

^fDetermined in CH₃CN using Nile blue (Φ_F = 0.27 in ethanol) as the reference dye.