Table 1.

Optical properties of o-nitrophenylenthanols with various substituted groups and their corresponding oxindoles.^[a]

Compds	R1	R2	λmax[c] [nm]	λmax[d] [nm]	λem[e] [nm]	φ[f]	F/F0[g]
1–1a	COOCH3	H	254	334	520	0.36	800
2–2a	H	COOCH3	230	290	401	0.15	200
3–3a	COOCH3	OCH3	334	321	502	0.17	230
4–4a	CN	H	254	290	514	0.047	32
5–5a	CHO	H	258	317	585	0.13	161
6–6a	COOH	H	262	282	485	0.027	21
7–7a	H	H	260	281	450	0.001	3
8–8a	CH2OH	H	273	321	420	0.001	5
9–9a	OCH3	H	312	325	458	0.001	5
10	H	OCH3	345	275	457	0.002	6

^[a]All the spectra were recorded in MeOH/PBS (3:1, v/v) solution with a concentration of 10 μM.

^[b]Fluorescence emission was not detected.

^[c]Absorption maxima in the 225–450 nm region for compound 1–10.

^[d]Absorption maxima in the 250–450 nm region for compound 1a–10 a.

^[e]Fluorescence emission in the 400–650 nm region.

^[f]Fluorescence quantum yields were measured using fluorescein (1a, 3a, 4a, and 5a) and DAPI (2a and 6a–10a) as standards.

^[g]Obtained by comparing the integrated area of emission.