4,4′-Azoxyanisole for temperature calibration of differential scanning calorimeters in the cooling mode—Yes or no?

By measuring the transition peak using differential scanning calorimetry in the heating and cooling modes, it has been confirmed that the nematic-to-isotropic liquid phase transition of 4,4′-azoxyanisole is of first order, but with some underlying additional phenomenon. As a consequence, this phase transition can only be used under certain precautions for temperature calibration of scanning calorimeters in the cooling mode.