Triarylamines Designed to Form Molecular Glasses. Derivatives of Tris(<i>p</i>-terphenyl-4-yl)amine with Multiple Contiguous Phenyl Substituents

The principles of crystal engineering can be used in a contrary way to help devise molecules that resist crystallization and form long-lived glasses. This can be achieved by making structural changes that thwart established patterns of crystallization. In using this strategy to block the crystallization of triarylamines, we have found that the introduction of methylpentaphenyl groups is particularly effective, presumably because they inhibit efficient molecular packing and normal intermolecular interactions.