Apex functionality dependent Frank-Kasper phases on dendron self-assembly

New complex sphere-packing of Frank-Kasper (FK) phases gradually emerge as the pioneering molecular platform to examine the assembly behaviors. For such purpose, we adopt a simple second-generation dendrons with a variety of apex functionalities to perform rich development of FK phases. Despite all the same dendritic wedges on body part of dendrons, the various sphere-packing phases are shown contributed from the different apex functionalities which attune the cohesive interactions. These sphere packing phases are measured and traced by in-situ small-angle X-ray scattering and FT-IR spectroscopy. The electron density maps of sphere-packing phases are reconstructed from X-ray scattering data to analyze each characteristic phase. The sphere particle sizes as well as isoperimetric quotient and coordination number are evaluated from electron density maps. To rationalize the free energy balance of dendron assemblies, we apply enthalpic/entropic effects which accommodate the cohesive energy of apex functionalities. Our approach to modulating the cohesive interactions in a basic second-generation dendron assembly envisions feasible strategy and primitive platform for manipulating diverse sphere-packing FK assemblies and quasiperiodic arrays.