Table Of Content4 0 Topics ni Current yrtsimehC
Molecular Inclusion and
Molecular Recognition-
setarhtalC I
Editor: E. Weber
With Contributions by
R. Gerdil, E H. Herbstein, .T C.W. Mak,
E Toda, E V6gtle, E. Weber, H. N. C. Wong,
D. Wors ch
htiW 96 serugiF dna 04 selbaT
galreV-regnirpS Berlin Heidelberg NewYork
London Paris Tokyo
This series presents critical reviews of the present position and future trends
in modern chemical research. It is addressed to all research and industrial
chemists who wish to keep abreast of advances in their subject.
As a rule, contributions are specially commissioned. The editors and publishers
will, however, always be pleased to receive suggestions and supplementary
information. Papers are accepted for "Topics in Current Chemistry" in
English.
I SBN 3-540-17307-2 springer-Verlag Berlin Heidelberg New York
ISBN 0-387-17307-2 Springer-Verlag New York Heidelberg Berlin
Library of Congress Cataloging-in-Publication Data
Molecular inclusion phenomena.
(Topics in current chemistry ; )041
Contents: Clathrate chemistry today / .E Weber -- Separation of enantioners by clathrate
formation /
D. Worsch, F. V6gtle -- Isolation and optical resolution of materials utilizing inclusion
noitazillatsyrc / F. Toda -- .cte
.1 Clathrate compounds. I. Weber, .E II. Gerdil, R. III. .seireS
QD1.F58 vol. 041 045 s 65613-68
QD474 2'2.145
ISBN 2-70371-783-0 (U.S.)
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Editorial Board
Prof. Dr. Michael J. S. Dewar Department of Chemistry, The University of Texas
Austin, TX 78712, USA
Prof. Dr. Jack D. Dunitz Laboratorium fiir Organische Chemie der
Eidgen6ssischen Hochschule
Universit/itsstraBe 6/8, CH-8006 Ztirich
Prof. Dr. Klaus Hafner Institut fiir Organische Chemie der TH
PetersenstraBe ,51 D-6100 Darmstadt
Prof. Dr. Edgar Heilbronner Physikatisch-Chemisches Institut der Universit~it
KlingelbergstraBe ,08 CH-4000 Basel
Prof. Dr. ~h6 It6 Department of Chemistry, Tohoku University,
Sendai, Japan 980
Prof. Dr. Jean-Marie Lehn Institut de Chimie, Universit6 de Strasbourg, ,1 rue
Blaise Pascal, .B P. Z 296/R8, F-67008 Strasbourg-Cedex
Prof. Dr. Kurt Niedenzu University of Kentucky, College of Arts and Sciences
Department of Chemistry, Lexington, KY 40506, USA
Prof. Dr. Kenneth N. Raymond Department of Chemistry, University of California,
Berkeley, California 94720, USA
Prof. Dr. Charles W. Rees Hofmann Professor of Organic Chemistry, Department
of Chemistry, Imperial College of Science and Technology,
South Kensington, London 7WS 2AY, England
Prof. Dr. Fritz V6gtle Institut ftir Organische Chemie und Biochemie
der Universit~it, Gerhard-Domagk-Str. ,1
D-5300 Bonn 1
Prof. Dr. Georg Wittig Institut f/it Organische Chemie der Universit~it
Im Neuenheimer Feld 270, D-6900 Heidelberg 1
Preface
Chemistry is at a crossroads. In fact chemists no longer just aim
at the synthesis of compounds via covalent linkage or the clarifica-
tion of chemical reaction mechanisms. More and more research
activities are directed to understand the nature of what is called
"weak intermolecular interactions" in a broader sense. Weak non-
covalent bonds involving neutral organic molecules are of vital
importance, e.g. in molecular biology, drug design etc.
The search for artificial host mimics possessing specific weak
interaction and complexation properties to ions and neutral
molecules has inspired scientists to work with great effort during
the past several years and much success can be reported. Different
subareas of research related to this matter have developed (crown
chemistry, cyclodextrins, calixarenes etc.). They are partly a
subject of former volumes of this series (cf. Top. Curr. Chem. 98,
101, 121, 123, 125, 128, 132, and 136).
However, there is another important subject in this range of
interest which has not been reviewed recently, but which is advanc-
ing so rapidly that reporting of its current state of knowledge is
much desirable. The point is research on lattice-type molecular
inclusion compounds or clathrates. The actual interest in these
compounds is broad, in a theoretical and practical sense, ranging
from the directed synthesis of new host molecules to the investiga-
tion of selective inclusion properties, molecular recognition, recep-
tor-substrate analogy, topochemistry, X-ray crystallography,
chemical analysis, molecular separation, compound protection,
detoxification and other applications of potential industrial value.
This book is the first of a two-volume series intending to provide
modern aspects of clathrate inclusion chemistry. Chapter 1 has
the character of an introduction. It shows briefly the evolution of
clathrate chemistry from the beginning in the early nineteenth
century to the present and leads to the current problems. A topic
which is particularly stressed in this volume is the use of clathrates
in enantiomer resolution (Chapters 2-4). Some structural problems
of general interest are also discussed (Chapter 5) and a new host
system, tetraphenylene, is introduced in Chapter .6
The second volume which is scheduled to appear soon will
concentrate mainly on design concepts and structural aspects
of new host molecules and inclusion compounds.
Bonn, November 1986 Edwin Weber
Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . IX
Clathrate Chemistry Today -- Some Problems and Reflections
E. Weber . . . . . . . . . . . . . . . . . . . . . . 1
Separation of Enantiomers by Clathrate Formation
D. Worsch, F. V6gtle . . . . . . . . . . . . . . . . . 21
Isolation and Optical Resolution of Materials Utilizing
Inclusion Crystallization
F. Toda . . . . . . . . . . . . . . . . . . . . . . . 43
Tri-o-Thymotide Clathrates
R. Gerdil . . . . . . . . . . . . . . . . . . . . . . 71
Structural Parsimony and Structural Variety Among
Inclusion Complexes
F. H. Herbstein . . . . . . . . . . . . . . . . . . . 107
Inclusion Properties of Tetraphenylene and Synthesis of
Its Derivatives
T. C. W. Mak, H. N. C. Wong . . . . . . . . . . . . . 141
Author Index Volumes 101-140 . . . . . . . . . . .
. . 165
Clathrate Chemistry Today -- Some Problems and
Reflections
Edwin Weber
Institut Chemie Organische ffir und der Bonn, Biochemie Universitfit
Gerhard-Domagk-Str. ,1 D-5300 Bonn-l, FRG
Table of Contents
1 Evolution of Crystal Inclusion (Clathrate) Chemistry -- A Very Short Survey 3
2 Why is Clathrate Chemistry of Current Interest? . . . . . . . . . . . . . 4
3 Directed Host Design versus Discovery by Chance . . . . . . . . . . . . 7
4 Calling a Spade a Spade: Classification and Nomenclature of Clathrates
(Including Host-Guest Compounds in General) . . . . . . . . . . . . . . 41
5 Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . . . 81
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Topics in Current Chemistry, Vol. 041
© Springer-Verlag, Berlin Heidelberg 7891
Clathrate Chemistry Today -- Some Problems and Reflections
1 Evolution of Crystal Inclusion (Clathrate) Chemistry --
A Very Short Survey
The chemistry of inclusion compounds has a long history .)1 Confirmed accounts on
the preparation of such chemical species date back to the beginning of the nineteenth
century. At that early time Davy, and shortly afterwards Faraday, reported of a
chlorine clathrate hydrate .)2
The chemistry of inclusion compounds also looks back on a lively history )3
There are many events of significance in the area of inclusion chemistry till the middle
of the twentieth century including the discovery of new inclusion compounds and
hosts 4 -8) (Fig. ,)1 among them the graphite intercalates, the 3-quinol and cyclodextrin
inclusion compounds, the Hofmann-type clathrates as well as the inclusion compounds
of tri-o-thymotide, Dianin's compound, the choleic acids, of phenols, of urea and
others specified in comprehensive monographs 9-az).
X
HO---O--OH
H2N NH 2
lax =o 2 3 HO"L~"~
lb x =s
4 5 6
OC3H HC0 3
o. o
7 8 9
Fig. .1 Representatives of well-known organic clathrate hosts
The most important event, however, emerged from the pioneering X-ray structural
work of H. M. Powell on inclusion compounds ,)31,1 e.g. the structural resolution of
the SO 2 clathrate of hydroquinone .)41 This was about 1945 and opened-up a whole
new science of the study of inclusion phenomena. Before the new tool was applied in
crystallography, the nature of inclusion compounds was understood only very vaguely,
but afterwards the Situation changed. Arousing from this fact, the interest in all types
of inclusion chemistry received an impetus of considerable extent which was only
3
