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.