Table 1.

Spectroscopic data for the new compounds (between 1 × 10^–6 M and 4 × 10^–5 M in DMF).

Compound	Absorption λmax (nm)	Log ε (M–1 cm–1)	Emission λmax (nm)	Stokes shift (cm–1)	ФF (DMF)a
3a	460	4.15	521	2545	0.69
4a	460	4.11	522	2582	0.68
3b	461	4.17	524	2608	0.83
3c	461	4.25	525	2644	0.78
3d	457	4.43	522	2687	0.73
4d	459	4.46	521	2593	0.72
3e	460	4.03	522	2547	0.71
3f	456	4.33	523	2809	0.83
4f	458	4.32	524	2750	0.66

^aExcitation at 436 nm. N,N’-Dibenzyl-DPP was used as the fluorescence quantum yield reference: Φ_F = 0.88, in chloroform [40].