1. Salen ligand: (S,S) Jacobsen's salen ligand was purchased from Sigma. The powder was dissolved in a solution composed of 1:2 dichloromethane to ethanol by volume, and the solution was left to slowly evaporate. After approximately 1 day, following drying of the solvent, thin rod-shaped crystals of a pale yellow color were observed. The population of crystals varied in size, some of suitable size (~0.5 mm long) for X-ray diffraction, but many much smaller. TEM grids were briefly dusted with crystalline powder, producing a distribution of sub-micron thick crystals suitable for MicroED. The anticipated salen ligand crystal polymorph was in space group P2 1 2 1 2 1 , CCDC ID: 129337, with cell constants a 6.78 Å, b 18.33 Å, c 27.75, Å α 90 o , β 90 o , γ 90 o .