Pyrene-Based Asymmetric Supramolecule: Kinetically Controlled Polymorphic Superstructures by Molecular Self-Assembly

To understand the kinetically controlled polymorphic superstructures of asymmetric supramolecules, a pyrene-based asymmetric supramolecule (abbreviated as Py3M) was newly synthesized by connecting two pyrene headgroups (Py) to a biphenyl-based dendritic tail (3M) with an isophthalamide connector. On the basis of thermal, microscopic, spectroscopic, and scattering results, it was realized that Py3M exhibited the monotropic phase transition between a stable crystalline phase (K1) and a metastable crystalline phase (K2). This monotropic phase transition behavior was mainly originated from the competitions of intra- and intermolecular interactions (π–π interactions and hydrogen bonds) as well as from the nanophase separations. From the two-dimensional (2D) wide-angle X-ray diffraction patterns and transmission electron microscopy images of the self-assembled Py3M superstructures, it was found that Py3M formed two synclinically tilted crystalline superstructures: the 6.75 and 4.4 nm periodicities of layered st...