Chapter 20
Twenty-Five Years’ History, Mechanism,
and Generality of Preferential
Enrichment as a Complexity
Phenomenon
Rui Tamura, Hiroki Takahashi, and Gérard Coquerel
Abstract Described here are the history, mechanism, and generality of ‘preferential
enrichment (PE)’ which is a spontaneous chiral resolution phenomenon observed
upon recrystallization of certain kinds of chiral racemic organic compounds from
organic or aqueous solvents. The use of dimorphic cocrystals of chiral racemic
compounds and achiral coformers could greatly expand the scope of PE. A thorough mechanistic investigation through (i) the direct observation of crystallization
processes by using in situ techniques such as attenuated total reflectance infrared
spectroscopy, temperature-controlled video-microscopy, and time-resolved X-ray
powder diffraction measurement, (ii) the graph set analysis of crystal structures of
deposited crystals, (iii) the kinetic/thermodynamic studies on the unique solubility
properties of two enantiomers, and (iv) the observation of equilibrium behavior of
an added labeled compound in solution and in the solid phases under PE conditions,
together with (v) the construction of the corresponding ternary phase diagram, has
indicated that PE is ascribed to an event of nonequilibrium ‘complexity system.’
Keywords Preferential enrichment · Spontaneous chiral resolution · Phase
transition · Chiral symmetry breaking · Complexity system
R. Tamura (B) · H. Takahashi
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
e-mail: tamura.rui.45x@st.kyoto-u.ac.jp
H. Takahashi
e-mail: takahashi.hiroki.2x@kyoto-u.ac.jp
G. Coquerel
Normandie Universuté, SMS, EA 3233, Université Rouen, Crystal Genesis Unit, 76821 Mont
Saint-Aignan Cedex, France
e-mail: gerard.coquerel@univ-rouen.fr
© Springer Nature Singapore Pte Ltd. 2020
M. Sakamoto and H. Uekusa (eds.), Advances in Organic Crystal Chemistry,
https://doi.org/10.1007/978-981-15-5085-0_20
405
Twenty-Five Years’ History, Mechanism,
and Generality of Preferential
Enrichment as a Complexity
Phenomenon
Rui Tamura, Hiroki Takahashi, and Gérard Coquerel
Abstract Described here are the history, mechanism, and generality of ‘preferential
enrichment (PE)’ which is a spontaneous chiral resolution phenomenon observed
upon recrystallization of certain kinds of chiral racemic organic compounds from
organic or aqueous solvents. The use of dimorphic cocrystals of chiral racemic
compounds and achiral coformers could greatly expand the scope of PE. A thorough mechanistic investigation through (i) the direct observation of crystallization
processes by using in situ techniques such as attenuated total reflectance infrared
spectroscopy, temperature-controlled video-microscopy, and time-resolved X-ray
powder diffraction measurement, (ii) the graph set analysis of crystal structures of
deposited crystals, (iii) the kinetic/thermodynamic studies on the unique solubility
properties of two enantiomers, and (iv) the observation of equilibrium behavior of
an added labeled compound in solution and in the solid phases under PE conditions,
together with (v) the construction of the corresponding ternary phase diagram, has
indicated that PE is ascribed to an event of nonequilibrium ‘complexity system.’
Keywords Preferential enrichment · Spontaneous chiral resolution · Phase
transition · Chiral symmetry breaking · Complexity system
R. Tamura (B) · H. Takahashi
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
e-mail: tamura.rui.45x@st.kyoto-u.ac.jp
H. Takahashi
e-mail: takahashi.hiroki.2x@kyoto-u.ac.jp
G. Coquerel
Normandie Universuté, SMS, EA 3233, Université Rouen, Crystal Genesis Unit, 76821 Mont
Saint-Aignan Cedex, France
e-mail: gerard.coquerel@univ-rouen.fr
© Springer Nature Singapore Pte Ltd. 2020
M. Sakamoto and H. Uekusa (eds.), Advances in Organic Crystal Chemistry,
https://doi.org/10.1007/978-981-15-5085-0_20
405