Preferred mirror image recognition in the
solid is not limited only to single component crystals but rather extends to
closely related compounds of opposite chirality, so-called quasiracemates.
During the cocrystallization experiment the almost enantiomeric molecules
self-organize and, with their alternating arrangement of left and right handed
enantiomers, often mimic one of the racemic parent structures, crystallizing in
an acentric subgroup of the latter. Their arrangement may imply pseudo
inversion between chemically different nearest neighbours of opposite chirality
and therefore the formation of pairs of molecules with a resulting non-zero
dipole moment.
My research exploits the statistical
preference for heterochiral crystals as a design tool to generate predictable molecular assemblies and leads the way to the
synthesis and characterization of binary crystals built up from square-planar
complexes. In order to understand the factors that
influence quasiracemate formation, I have designed, synthesized and
crystallographically characterized sets of ortho-metallated complexes of different chirality that form
approximately centrosymmetric patterns. X-ray studies of the enantiomeric,
racemic and quasiracemic crystal structures provide evidence of the role of
molecular topology to quasiracemate formation and contributes to the knowledge
base of exploitable molecular features for the design of binary solids.