Chapter 22
Molecular Recognition by Inclusion
Crystals of Chiral Host Molecules
Having Trityl and Related Bulky Groups
Motohiro Akazome and Shoji Matsumoto
Abstract Molecular recognition by inclusion phenomena is a useful application of
organic crystals. So, in this research, first, we discuss how several recent examples
of inclusion crystal methods have been overviewed in the optical resolution field.
Then, we focus on the installation of trityl and related bulky groups, which enable
compounds possible to settle guest molecules to form inclusion crystals. Some hosts
of amines and amino-acid derivatives having trityl or 9-phenyl-9-xanthenyl groups
include several neutral guests to construct inclusion crystals and achieve structural isomer separation and optical resolution. Finally, we report how salts between
N-trityltyrosine and tert-butylamine include 1-(1-naphtyl)ethanol with high enantioselectivity of 96% ee (R). Through this review, we recognize trityl and related bulky
groups as crystal engineering tools that conduct inclusion ability to host candidates.
Single-crystal X-ray analyses of these inclusion crystals show us that inclusion with
low enantioselectivity is often due to the statistically disordered structure of guests.
The method of suppressing this statistic disorder to reach high enantioselective
inclusion remains unknown.
Keywords Molecular recognition · Inclusion crystals · Amino acid · Trityl group
22.1 Introduction
In the comprehensive reviews of our previous book (2015), we dealt with chiral recognition with inclusion crystals of amino-acid derivatives having trityl groups [1]. We
will expand on the former review by summarizing the five-year progress of molecular recognition with inclusion crystals of chiral substance-based host molecules
with bulky groups.
M. Akazome (B) · S. Matsumoto
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba
University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
e-mail: akazome@faculty.chiba-u.jp
© 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_22
457
Molecular Recognition by Inclusion
Crystals of Chiral Host Molecules
Having Trityl and Related Bulky Groups
Motohiro Akazome and Shoji Matsumoto
Abstract Molecular recognition by inclusion phenomena is a useful application of
organic crystals. So, in this research, first, we discuss how several recent examples
of inclusion crystal methods have been overviewed in the optical resolution field.
Then, we focus on the installation of trityl and related bulky groups, which enable
compounds possible to settle guest molecules to form inclusion crystals. Some hosts
of amines and amino-acid derivatives having trityl or 9-phenyl-9-xanthenyl groups
include several neutral guests to construct inclusion crystals and achieve structural isomer separation and optical resolution. Finally, we report how salts between
N-trityltyrosine and tert-butylamine include 1-(1-naphtyl)ethanol with high enantioselectivity of 96% ee (R). Through this review, we recognize trityl and related bulky
groups as crystal engineering tools that conduct inclusion ability to host candidates.
Single-crystal X-ray analyses of these inclusion crystals show us that inclusion with
low enantioselectivity is often due to the statistically disordered structure of guests.
The method of suppressing this statistic disorder to reach high enantioselective
inclusion remains unknown.
Keywords Molecular recognition · Inclusion crystals · Amino acid · Trityl group
22.1 Introduction
In the comprehensive reviews of our previous book (2015), we dealt with chiral recognition with inclusion crystals of amino-acid derivatives having trityl groups [1]. We
will expand on the former review by summarizing the five-year progress of molecular recognition with inclusion crystals of chiral substance-based host molecules
with bulky groups.
M. Akazome (B) · S. Matsumoto
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba
University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
e-mail: akazome@faculty.chiba-u.jp
© 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_22
457