Giant molecules with varying geometric features by programming the unit sequence

Abstract

In this study, we modularly prepared a library of giant molecules using molecular nanoparticles – polyhedral oligomeric silsesquioxane (POSS) – as repeat units, with precise control over composition, regio-configuration, and sequence. Benefiting from the enlarged unit size, the assembly behaviors of these giant molecules are found to be sensitive to subtle structural variations. The precise chemical structure rules out molecular “defects” and serves as an ideal platform to resolve minute differences. The regio-configuration directly impacts the spatial arrangement of the neighboring POSS units, resulting in distinct phase behaviors. Molecular geometry, which stems from the monomer sequence, plays a crucial role in the self-assembly process. Simply changing the position of the alkyl ligands on the peripheries of particles generates substantial differences in the period spacing and phase stability, and in some cases even triggers a phase transition toward distinct structures.