20 Twenty-Five Years’ History, Mechanism, and Generality …
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Fig. 20.16 The proposed
mode of polymorphic
transition of racemic or
nonracemic cocrystal 2.
a Transformation of a
metastable form into a stable
one. This is the case in which
an even number (four in this
case) of homochiral l chains
are surrounded by two
d chains in the metastable
form, resulting in partial
crystal disintegration after
polymorphic transition.
b Hypothetical type B cyclic
dimer chain structure in the
cocrystal with orientational
disorder at the position of the
amino group on an
asymmetric carbon atom.
c Schematic illustration of
panel b. Reprinted with
permission from Ref. [35]:
Copyright 2020 American
Chemical Society