Table 1. Optical data of (R,R)-c-, (S,S)-c-, P-ap-, and M-ap-BBTE in CH₃CN at 293 K.

Compound	λOD,max[a] (nm) [ε (103 M−1 cm−1)]	λCD,max[a] (nm) [Δε (M−1 cm−1)]	Φo-c[b] (%)	Φc-o[b] (%)	CR[c] (%)	[α]633[d] (°) [PSS at 280 nm]
M-ap-BBTE	282 [36.4]	280 [+24.8]	73	—	92	+424 [−1891]
(S,S)-c-BBTE	515 [6.39]	503 [−19.4]	—	6.0	>99	−2109
P-ap-BBTE	282 [35.6]	280 [−25.5]	72	—	92	−420 [+1881]
(R,R)-c-BBTE	515 [6.32]	503 [+19.1]	—	5.8	>99	+2095

[a] Typical absorption and CD maxima of ring-open isomer in UV region and ring-closed isomer in visible region, respectively. OD represents ‘optical density'.

[b] Quantum yields of photocyclization at 313 nm and photocycloreversion at 517 nm, with uncertainty around ±5% and ±0.5%, respectively.

[c] Conversion ratio to ring-closed isomer (under UV irradiation, λ = 280 nm), and ring-open isomer (under visible light irradiation, λ > 470 nm), calculated from absorption spectra.

[d] Specific optical rotation at 633 nm, outside the absorption region (λ < 580 nm) of both ring-open and ring-closed isomers.