The optical rotation of streptorubin B and comparison with the computational spectroscopy for the pair of its atropisomers and homodimers show that its atropisomers by far dominate the chiroptical effects and where atropisomerism is a dynamic phenomenon, with a non-equilibrium population of atropisomers and/or its dimers, the chiroptical responses are likely to vary with time, concentration, temperature and the anion of the salts used.