Table 1. Summary of the Photophysical Properties of the Switchable Photoprobes 8–19^a.

compound	λmax (E) [nm]	λmax (Z) [nm]	λiso [nm]	t1/2 [days]b	PSS (E → Z)d (%)	PSS (Z → E)d (%)
8	328	430	277, 395	5.5	94	72
9	330	428	281, 391	3.0	93	77
10	332	430	285, 393	1.7 (1.0c)	86	81
11	333	430	285, 396	1.2	87	85
12	330	430	281, 390	3.0 (1.4c)	95	74
13	332	425	285, 405	0.5	85	79
14	332	430	285, 400	1.4	81	86
15	320	440	277, 380	2.7	88	69
16	320	430	277, 390	3.1	89	83
17	323	425	274, 375	28.6	93	88
18	340	427	293, 403	6.6	94	82
19	333	431	285, 402	54.5	93	87

^aIsomerization was obtained by irradiation with 340 nm (Z-isomer) and 420 nm for 8–17 and 528 nm for 18 and 19 (E-isomer), respectively. Concentration: 20 μM in HEPES buffer (25 mM HEPES, 2.5 mM CaCl₂, 1 mM MgCl₂, pH = 7.4) + 0.1% DMSO.

^bPreirradiation with 340 nm, measured at 25 °C.

^cMeasured at 37 °C.

^dPrior irradiation with 340 nm (Z-isomer) and 420 nm for 8–17 and 528 nm for 18 and 19 (E-isomer), respectively, for 2 min to ensure the ratio at the PSS. PSS determination was done by analytical C₁₈-RP-HPLC at the appropriate isosbestic points.