Table 1.

Photophysical properties of squaraine rotaxane derivatives

Compound	Solvent	λabs/nm	λema/nm	Φ fb
1	THF	631	650	0.61
2a	THF	639	659	0.70
	THF–H2O (4 : 1)	643	667	0.58
2b	THF–H2O (4 : l)	650	676	0.15
3	THF	644	672	0.61
4	H2O	650	669	0.08
6	CHCl3	661	704c	0.47
7	THF	638	657	0.74
8	H2O	653	675	0.20

^aSolutions were excited at 590 nm and emission monitored in the region 600–750 nm for estimating Φ_f.

^bFluorescence quantum yields were determined using 4,4-[bis(N,N-dimethylamino)phenyl]squaraine dye as the standard (Φ_f = 0.70 in CHCl₃), error limit ±5%.

^cSolution was excited at 605 nm and emission monitored in the region 620–850 nm for estimating Φ_f.