Abstract:
The hydrate dimorphs of the antiviral drug EIDD-
1931 (EIDD) exist as tautomers possessing different conformations,
synthon preferences, thermal decomposition profiles, and
mechanical properties. This coexistence of manifold contrasting
structural features is unusual and makes the hydrate dimorphs of
EIDD-1931 exceptional. As analogs of uridine and cytidine, the
tautomers corresponding to the crystal forms (Form I and Form
II) of EIDD help effectively block viral RNA replication. With
regard to the analogous nucleosides, the computed MESP of EIDD
exhibits extensive alterations and disproportionate distribution of maxima and minima sites, contributing to its hydration
characteristics. The water of crystallization and its efflorescence have a direct impact on the thermal decomposition profiles as well as
the nanomechanical response of the crystal forms because of their distinct roles in the stabilization of the structure as a two-donor,
two-acceptor interaction center occupying isolated sites in Form I as opposed to a one-donor, one-acceptor moiety confined to a
void-filling role in Form II. From a broader perspective, the nanomechanical responses correlated to the interaction characteristics,
and dehydration events are remarkable in deriving a molecular basis of the properties in pharmaceutics wherein a major share of the
pharmaceuticals exists as hydrates.
