*2.2. Spectroscopy and Thin Film Preparation*

UV-Vis Spectra were measured in chloroform at a concentration of 1.5 <sup>×</sup> 10−<sup>4</sup> mol/L using a Perkin-Elmer Lambda 900 spectrophotometer (Norwalk, CT, USA). To measure the Faraday rotation as well as polarized optical microscopy (POM) [21], the materials were placed in LC cells with a 3 μm gap. To fill the cells with the organic materials, a heating plate heated the cells to a temperature of 5 to 10 ◦C higher than the melting temperature of the desired molecules. A small amount of material was deposited next to the gap. It subsequently melted, and entered the cell through capillary action. After the LC cell had been filled and cooled, a homemade heating and cooling device reheated the filled LC cells to 5 ◦C above the melting temperature of the organic material, and cooled the samples to r.t. by 0.1 ◦C/min. An Olympus microscope was used for obtaining POM images. Faraday rotation spectra were collected using a photoelastic modulation magneto-optical setup described by Vandendriessche et al. from 350 to 700 nm, every 2 nm [4]. The optical rotation was measured at varying magnetic field from 0 to 0.5 T. A blank was also measured to nullify the effects of the glass. Using linear regression, the magnetic rotation was calculated from the slope. The Verdet constant ( ◦/Tm) was then calculated by dividing the magnetic rotation by the thickness of the sample inside the LC cell, i.e., 3 μm. Smoothing of the curves was done using Savitsky–Golay method in Origin. We confirmed that the sample was in the plane was isotropic by measuring at different azimuthal angles of the samples at 400 nm (Figure S1).
