Table 1. Photophysical data of tetrazine-caged fluorophores and their nitrile derivatives.

Compound number	Compound	λ abs (nm)	λ em (nm)	ε × 104 (M–1 cm–1)	Φ MeCN	Fluorescence increase d
1	Tz-BODIPY	490	509	1.9	0.004 a	178-Fold
2	CN-BODIPY	492	509	3.6	0.60 a	—
3	Tz-Coumarin	347	416	1.8	<0.001 b	86-Fold
4	CN-Coumarin	351	417	1.9	0.19 b	—
5	Tz-Si-Rhodamine	651	671	2.6	0.011 c	35-Fold
6	CN-Si-Rhodamine e	652	671	2.4	0.34 c	—
7	Tz-BODIPY-MOR	495	511	2.6	0.03 a	45-Fold
8	Tz-BODIPY-Ts	492	510	1.8	0.02 a	36-Fold
9	Tz-BODIPY-TPP	494	509	3.0	0.007 a	97-Fold
10	Tz-BODIPY-Halo	491	509	2.4	0.002 a	141-Fold

^aFluorescein in 0.1 M NaOH.

^bQuinine sulfate in 0.5 M H₂SO₄ was used as a reference for measuring the quantum yields.

^cRhodamine B in water was used as a reference for measuring the quantum yields.

^d254 nm light activation (1400 μW cm^–2).

^eMeasured after irradiation of compound 5 with 254 nm light.