Polymorphic Diversity: <i>N</i>‑Phenylbenzamide
as a Possible Polymorphophore
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Abstract
In this work, we identify and describe
a moiety that may be capable
of encouraging the formation of polymorphs. Four new <i>N</i>-phenylbenzamide-based compounds have been synthesized yielding four
pairs of polymorphs upon recrystallization. The structures of these
have been discussed and compared with the previously reported polymorphs
of <i>N</i>-[2-(hydroxymethyl)phenyl]benzamide.
The results indicate that the conformation of the <i>N</i>-phenylbenzamide group is generally constant but is sometimes altered
by the crystal packing. The <i>N</i>-phenylbenzamide group
is capable of intermolecular N–H···O hydrogen
bonding but requires a change in conformation which is generally resisted
by the molecule. As a consequence, weak forces such as C–H···O,
C–H···N, C–H···π,
and π···π interactions play significant
but varying roles in these structures. One possible reason for the
varying nature of the π···π interactions
may be due to the variation of the electrostatic potential across
the <i>N</i>-phenylbenzamide group in which negative and
positive regions alternate across the face of the molecule. It is
the combination of all these attributes that possibly leads to polymorphism
being observed in the structures reported here