Engineering of Rotational Dynamics via Polymorph Manipulation.

We used dielectric spectroscopy to uncover the rotational dynamics of the fluorophenyl rotor in different polymorphs of two amphidynamic crystals with identical sizable cores. The rotor solid-state dynamics were investigated in various crystalline environments. We did not change the chemical structure of the crystal itself, but while maintaining the same atomic composition, we changed the arrangement of atoms in space by taking advantage of crystal polymorphism, providing an alternative approach to one based on searching for new, chemically different entities with desirable functionality. We demonstrated that via polymorph variation, we can efficiently improve rotor solid-state performance and reduce the rotational barrier height by 30%. Our findings advance the understanding of polymorph engineering as a prospective trend in amphidynamic crystal technology, which uses the phenomenon of crystal polymorphism to design crystals displaying applicable internal rotational dynamics.