Table Of Content49
Topics in Current Chemistry
Molecular Inclusion and
Molecular Recognition-
setarhtalC II
Editor: E.Weber
With Contributions by
R. Bishop, M. Czugler, .I G. Dance, I. Goldberg,
.J Rebek, Jr., .F Toda, E.Weber
With 031 Figures and 54 Tables
Springer-Verlag Berlin Heidelberg NewYork
London Paris Tokyo
This series presents critical reviews of the present position and future trends
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ISBN 3-83391-045-3 Springer-Verlag Heidelberg Berlin New York
ISBN 3-83391-783-0 Springer-Verlag New York Heidelberg Berlin
Library of Congress Cataloging-in-Publication Data
Molecular and inclusion molecular recognition -- clathrates II.
current in (Topics chemistry ; )941
index. Includes
.1 Clathratecompounds. I. Weber, .E I[. Bishop, R. [I[. Series.
QD1.F58 vq].149 [QD474] 540s 59951-88
ISBN 3-83391-783-0 (U.S.) ]2'2.145[
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Guest Editor
Professor Dr. Edwin Weber
Institut f~r Organische Chemie und Biochemie der Universit/it
Bonn, Gerhard-Domagk-Str. ,1 D-5300 Bonn 1
Editorial Board
Prof. Dr. Michael J. S. Dewar Department of Chemistry, The University of Texas
Austin, TX ,21787 USA
Prof. Dr. Jack D. Dunitz Laboratorium rQf der Chemic Organische
Hochschule Eidgen6ssischen
eBartsst~tisrevinU Z/irich CH-8006 6/8,
Prof. Dr. Klaus Hafner Institut f~ der Chemie Organische TH
eBartsnesreteP ,51 Darmstadt D-6100
Prof. Dr. Edgar Heilbronner Institut der Universit/it Physikalisch-Chemisches
eBartsgreblegnilK ,08 CH-4000 lesaB
Prof. Dr. ,~h6/t6 Department of Chemistry, Tohoku University,
Scndai, Japan 089
Prof. Dr. Jean-Marie Lehn de Institut Strasbourg, de Chimie, Universit6 ,1 rue
esialB Pascal, .B .P Z 296/R8, 80076-F Strasbourg-Cedex
Prof. Dr. Kurt Niedenzu University of Kentucky, College of Arts and secneicS
Department of Chemistry, Lexington, KY ,60504 USA
Prof. Dr. Kenneth N. Raymond Department of Chemistry, University of California,
,yelekreB California ,02749 USA
Prof. Dr. Charles W. Rees Hofmann Professor of Department Organic Chemistry,
of College Imperial Chemistry, of ecneicS Technology, and
South Kensington, London 7WS 2AY, England
Prof. Dr. Fritz Viigtle Institut Organische Chemie fiir und eimehcoiB
Gerhard-Domagk-Str. der Universifftt, ,1
0035-D Bonn 1
Table of Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . IX
The Significance of Molecular Type, Shape and
Complementarity in Clathrate Inclusion
I. Goldherg . . . . . . . . . . . . . . . . . . . . .
Functional Group Assisted Clathrate Formation --
Scissor-Like and Roof-Shaped Host Molecules
E. Weber, M. Czugler . . . . . . . . . . . . . . . . . 45
New Types of Helical Canal Inclusion Networks
R. Bishop, I. G. Dance . . . . . . . . . . . . . . . . 137
Recent Progress in Molecular Recognition
J. Rebek, Jr . . . . . . . . . . . . . . . . . . . . . . 189
Reaction Control of Guest in Compounds Host-Guest Inclusion
Complexes
F. Toda . . . . . . . . . . . . . . . . . . . . . . . 211
Index Author Volumes 101-149 . . . . . . . . . . . . . 239
Table of Contents of Volume 041
Molecular Inclusion and Molecular Recognition -- Clathrates I
Preface
Clathrate Chemistry Today -- Some Problems and Reflections
E. Weber
Separation of Enantiomers by Ciathrate Formation
D. Worsch, F. V6gtle
Isolation and Optical Resolution of Materials Utilizing
Inclusion Crystallization
F. Toda
Tri-o-Thymotide Clathrates
R. Gerdil
Structural Parsimony and Structural Variety Among
Inclusion Complexes
F. H. Herbstein
Inclusion Properties of Tetraphenylene and Synthesis of
Its Derivatives
T. C. W. Mak, H. N. C. Wong
Preface
This book is the second of a two-volume series that attempts to bring together in-depth
investigations in currently important areas of "'molecular inclusion and molecular
recognition" mainly based on clathrate formation. The first volume of this series
(Volume 140) was published in 1987.
The well-known fact that certain biological compounds (enzymes, carriers, etc.)
can bind substrates selectively while markedly enhancing their chemical modifica-
tion or transporting them through membranes has inspired chemists to design and
synthesize molecules capable of mimicking these and other features. Remarkable
progress has already been achieved in the preparation of macrocycles and related
systems which combine specifically with ions as well as with various uncharged mole-
cules and provide functional properties based on recognition, binding, catalysis, and
transport of ions and molecules. The 1987 Nobel Prize for chemistry was awarded
to the trio of scientists Pedersen, Cram, and Lehn who did fundamental work on
this relatively new field, called "'host-guest" or "supramolecular chemistry" [cf.
Weber, E., Vrgtle, F.: Nachr. Chem. Tech. Lab. 35, 1149 (1987)].
A supramolecular species (host-guest compound) results from the interaction of a.
substrate (the guest) with its receptor molecule (the host). Normally one fienndcsl osure
of the guest molecule in the cavity formed by a host framework (cf. crown complexes,
cryptates). The host-guest association is not established by covalent and ionic bonds,
but is caused by H-bonds and/or van der Waals interactions. With reference to the
chemistry of weak intermolecular bonds, supramolecular association has contributed
to the fundamental understanding of the elementary interactions on which molecular
recognition and binding is based and represents an interface between chemistry and
biology.
Within this approach, clathrates (for a definition see Chapter 1 in Vol. 041 of this
series) and related lattice-type aggregates may be considered as ralucelomarpus-itlum
systems where guest molecules are included in a crystal matrix. They allow a great
many applications which have been specified in Vol. 140, first of all the separation of
enantiomersb y enantioselective recognition and inclusion of racemic guest molecules.
Unfortunately, chemistry of clathrates has not made such rapid progress as the
organic complexes until recently. Now new approaches and techniques have amply
encouraged the design of selective host molecules and clathrate structures. The aim
of this book is to illustrate important developments in these fields including functional
group assisted clathrates, helical channel formation, architecture of crystalline clefts,
and other molecular design principles given in Chapters 1-4, while Chapter 5 is
devoted to the fascinating possibilities of stereocontrolled solid-state reactions using
clathrate inclusion. Thus the present book is not a mere sequel of Volume 140 (part I
of this topic) published in 1987, but complements the theme.
Both books could only be completed with the assistance of the individual contributing
authors. Their efforts cannot be underestimated, and the editor wishes to express his
heartfelt appreciation.
Bonn, April 1988 Edwin Weber
The Significance of Molecular Type, Shape dna
Complementarity in Clathrate Inclusion
Israel Goidberg
School of Chemistry, Sackler Faculty of 69978 University, Ramat-Aviv, Tel-Aviv Exact Sciences,
Israel
Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Solvates and Clathrates as Common Phenomena . . . . . . . . . . . . . 3
2.1 General Considerations . . . . . . . . . . . . . . . . . . . . . . 3
2.2 Solvates -- The Simplest Example of Lattice Inclusion . . . . . . . . 3
2.3 Channels and Cages in Organic Lattices . . . . . . . . . . . . . . . 12
3 Molecular Design of Hosts for the Formation of Inclusion Compounds with
Apolar Guests . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.1 Background -- Clathrate Inclusion Compounds of Spirotriphosphazenes 81
3.2 "Wheel-and-Axle" Type of Host Molecules in Clathrate Inclusion . 91
3.3 Substituted Allenes as Clathrate Hosts . . . . . . . . . . . . . . . 22
4 Selective Complexations of Polar Guests by Hosts Containing Functional
"Sensors" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.1 Coordinato-Clathrates of N,N'-Ditritylurea . . . . . . . . . . . . . 25
4.2 Separation of Structural Isomers by Crystalline Complexation with 1,1-
Di(p-hydroxyphenyl)cyclohexane . . . . . . . . . . . . . . . . . 30
4.3 Chiral Inclusion Complexes of 2,2'-Dihydroxy-l,l'-Binaphthyl with
Phosphinates and Phosphine Oxides . . . . . . . . . . . . . . . . 38
5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
scipoT in Current Chemistry, Vol. 941
© Springer-Vetlag, Berlin Heidelberg 8891
learsI grebdloG
1 Introduction
The formation of clathrate inclusion compounds in which guest species are enclosed
by channels or cages that occur in a given host lattice was first discovered in the
middle of the past century ,~1 Since then a large number of clathrates and solvates,
found mostly by chance as by-products of research in other areas, have been charac-
terized 2-4~. These multicomponent systems attracted however relatively little atten-
tion, and a systematic development of their chemistry was very slow. The rapid
advancement of host-guest chemistry in the last two decades, since the pioneering
work of Pedersen on crown ethers ,)5 provided a turning point in this respect. Initially,
the class of molecular inclusion complexes, in which larger host species are able to
enclose and bind smaller guest molecules, has been subjected to most intensive investi-
gations aiming at the synthesis of molecular models that can mimic the chemical
behaviour of natural systems. The success was overwhelming with respect to the
number and complexity of suitable compounds (ligand-substrate complexes, iono-
phores, molecular receptors) that have been prepared and analyzed. Most extensively
studied were macro(poly)cyclic hosts of the crown/cryptate type which turned out
to be excellent and often selective complexors of metal ions and amino acid deri-
vatives 6-s). The presence of O and/or N heteroatoms in these macrocycles made
them also suitable for an effective complexation through hydrogen bonding with
uncharged guest molecules containing proton donating sites such as acidic CH,
NH or OH 9-11k Most recent investigations of models for molecular separation
and transport processes relate to carefully designed organic systems which involve
encapsulation of apolar guests within apolar host molecules )4~-z1
As a natural development of the successful molecular inclusion concept, which
involved electrostatic 6-u~ as well as van der Waals x2-14) forces between the inter-
acting host and guest entities, an increasing interest has been shown in the systematic
study of lattice-inclusion type systems. A considerable effort has been devoted to
the design of new hosts for the formation of stable crystalline clathrates and the
improvement of selective complexations with potential guests. Suitable examples of
clathrates studied in recent years include hosts such as Dianin's compounds ,)as~
perhydrotriphenylene ,)b51 cyclotriveratrylene ,)c51 triphenylmethane ,)d51 hexakis-
(arylthio) and -(arylthiomethyl)benzenes ,)e51 tri-o-thymotide (TOT) ,)f51 and choleic
acids )gs~ (cf. Fig. 1 in Ch. 1 of Vol. 140). Selected series of such clathrate inclusion
systems have particularly been useful in research of photochemical reactions in the
solid state ,6~ )7~ and of selective molecular complexation that is central to biological
phenomena is, )9~
This report surveys the structural aspects ofclathrates formed with a series of other
host systems, illustrating the conceptual progress made over the last few years in
our ability to achieve a better controlled and more selective lattice-type complexa-
tion of uncharged molecules. It also emphasizes an important observation that in
molecular separations the approach of lattice inclusion can often be as effective
and easy to apply as that of molecular inclusion; both phenomena utilize a similar
variety of binding forces by which host and guest constituents are held together in
a structured way. Most of the examples presented below were structurally analyzed
in this laboratory, and they refer to systems based on organic host lattices only. They
reflect on the author's general interest in structural aspects of host-gnest chemistry.
