Compound 2b in dichloromethane (DCM) shows well-resolved absorption spectrum with five major vibronic peaks at 336, 351, 373, 392, and 424 nm (Fig. ). Compound 1 displays a more intense absorption spectrum with the major absorption peaks at 382, 413 and 470 nm, which are red-shifted as compared to 2b, in accordance with the extended π-conjugation pathway. However, due to the localized aromatic character, the shift is not significant. The absorption band with peak at 470 nm can be correlated to partially allowed HOMO→LUMO electronic transition (oscillator strength f = 0.0014) according to the time-dependent (TD) DFT calculations (Table in Supplementary Information). The HOMO and LUMO coefficients are delocalized along the whole backbone (Fig. ), again indicating a fully conjugated electronic structure. Compound 2b and 1 exhibit similar well-resolved fluorescence spectra with two major emission peaks at 462/486 nm and 486/518 nm, respectively (Fig. ). The slightly red-shifted emission band in 1 as compared to 2b can be explained by the same reasons. The absolute fluorescence quantum yields (FLQY) of 2a and 1 in DCM was determined to be 62.0% and 13.6%, respectively, by using integrating sphere technique. The relatively low FLQY of 1 could be ascribed to its small oscillator strength for the S0→S1 transition, which however will benefit absorption dissymmetry factor of their enantiomers. Furthermore, their corresponding fluorescence lifetimes were measured as 7.3 ns and 6.7 ns, respectively. The chiral resolution of 2b and 1 were successfully achieved by using chiral HPLC (Fig. in Supplementary Information). The absolute configurations were assigned as (+)380-2b = (P,P,P)-2b/(-)380-2b = (M,M,M)-2b, while (+)380-1 = (P,P,P)-1/(-)380-1 = (M,M,M)-1 based on experimental (Fig. ) and theoretical (Fig. in Supplementary Information) circular dichroism (CD) spectra. The largest absorption dissymmetry factor |gabs| value of 0.012 for 2b is recorded from higher energy transitions, and there is also a very small |gabs| value (< 0.001) through S0-S1 transition. In contrast, 1 has the largest |gabs| value of 0.019 originating from the S0-S1 transition. The larger gabs value of 1 may be owing to its D3 symmetric, fully conjugated, triply twisted Möbius structure while possess an ideal topology for electric transitions to enhance magnetic transition dipole moment. According to the calculations of dissymmetry factor, g value can be simplified as the equation: g = 4|μ||m|cosθ/(|μ| 2 + |m| 2 ), wherein μ, m, and θ are the electric transition dipole moment, the magnetic transition dipole moment, and the angle between μ and m, respectively. For most single organic molecules, |m|«|μ|, thus, the key point to improve the g value is to suppress μ and extend m, meanwhile keeping the angle between μ and m to approach 0⁰ or 180⁰. In our cases, the |gabs| value around 424 nm for 2b is originated from S0→S1, S0→S2 and S0→S3 transitions according to the TD DFT calculations (Table in Supplementary Information), while S0→S2 and S0→S3 transitions with large oscillator strength (f = 0.95) made the major contributions. The calculated |gabs| value of 2b for S0→S2/S3 transitions with large |μ| and small |m| value, and not perfect angle θ (76.8⁰) between them is 0.001 (Fig. and Table in Supplementary Information). The asymmetric electric structures of 2b caused the very small |gabs| value in the lowest energy level transitions. In contrast, the calculated |gabs| value of 1 for S0→S1 transition around 480 nm is 0.87 with a smaller |μ| and larger |m|, and a perfect angle θ (0.8⁰) between them (Fig. and Table in Supplementary Information). The highly symmetric and fully conjugated structure of 1 enables electric transition dipole moment to cancel out in the plane of molecule and form a larger magnetic transition dipole moment, further prompting the two vectors of |μ| and |m| perpendicular to the molecular plane.