. Author manuscript; available in PMC: 2016 Jun 5.

Published in final edited form as: J Org Chem. 2015 May 20;80(11):5600–5610. doi: 10.1021/acs.joc.5b00503

Table 2.

Fluorescence Quantum Yield (ϕ), Lifetime (τ), and Radiative and Nonradiative Decay Rate Constants (k_r and k_nr) of Compounds 3 and 4 in Different Solvents^a

solvent	ε	ϕ (3)	ϕ (4)	τ/ns (3)	τ/ns (4)	k_r/ns⁻¹ (3)	k_r/ns⁻¹ (4)	k_nr/ns⁻¹ (3)	k_nr/ns⁻¹ (4)
hexanes	2.02	0.16	0.50	0.46	0.85	0.35	0.59	1.83	0.59
dioxane	2.3	0.10	0.50	0.41	0.94	0.24	0.53	2.20	0.53
benzene	2.3	0.10	0.59	0.40	0.85	0.25	0.69	2.25	0.48
toluene	2.4	0.12	0.58	0.43	0.86	0.28	0.67	2.05	0.49
CHCl₃	4.8	0.07	0.44	0.34	0.92	0.21	0.48	2.74	0.61
EtOH	25	0.05	0.66	0.33	1.63	0.15	0.40	2.88	0.21
MeOH	33	0.04	0.65	0.32	1.82	0.13	0.36	3.00	0.19
MeCN	36.6	0.04	0.60	0.23	1.30	0.17	0.46	4.17	0.31
DMF	38.3	0.06	0.67	0.32	1.34	0.19	0.50	2.94	0.25
DMSO	47	0.07	0.76	0.33	1.51	0.21	0.50	2.82	0.16
H₂O^b	78.5	0.06	0.54	0.30	2.31	0.20	0.23	3.13	0.20

ε: dielectric constant; ϕ: fluorescence quantum yield; τ: fluorescence lifetime determined via time-correlated single-photon counting (TCSPC); k_r and k_nr: radiative and nonradiative decay constants, determined using eqs 1 and 2. The table is sorted in the ascending order of ε.

An aqueous solution buffered by HEPES (100 mM) at pH 7.4.