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Book Review Supramolecular Photochemistry. By V. Balzani and F. Scandola

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style have become identical-an ironic twist in the social
history of science. Only the list of coauthors now looks different-on this, however, one should read Professor Djerassi
who has more to say on this subject.. .
The appendices, in which the subsequent life histories of
the members of these seven classic examples of important
research groups have been thoroughly investigated and detailed, are impressive, and quantify the theories put forward.
Whereas groups of one type have mainly produced scientists
useful to industry, and have therefore appeared as an attractive proposition for the market, those of another type can
proudly point to an output of academic scientists that is well
above average, both in quantity and quality - though many
of these were lost to Germany as victims of persecution in the
Nazi era. In passing it is interesting to note that although the
number of women was still small in those days (we are talking here ofthe years before 1914!), there were somenevertheless, even though few of them succeeded in rising beyond the
level of head of a clinical laboratory (or, with luck, a teacher
of Greek after having emigrated).
The contents of the book have been collected together
from many sources. However, readers who are already familiar to some extent with the main threads of the development
of biochemistry in Germany will not find much information
here that is fundamentally new. On the other hand, the particular appeal of this account, which makes it especially interesting for us in Germany, is in the critical discussion that
comes from the author’s more detached perspective, seen
from the viewpoint of the Angloamerican scientific tradition. Also the descriptions of the characters of the protagonists, which are mainly taken not from the anecdotal folklore
of chemistry but from correspondence and scientific publications, add a more human side to the facts. Which of us will
eventually have a Fruton to write about us?
Finally, this volume provides comforting evidence for
those who love books that it is still possible nowadays, if the
will is there, to make a book with care: with clear and attractive printing, on good paper with a generous margin, with
sewn pages and a substantial binding, and, last but not least,
with the characteristic smell of a book. It is satisfying to find
here that a substantial content and a durable quality of production each enhance the other.
Lothar Jaenicke
Institut fur Biochemie
der Universitat Koln (FRG)
Supramolecular Photochemistry. By I.: Balzani and I? Scandola. Ellis Horwood, New York, 1991.427 pp., hardcover
$121 .OO.-ISBN 0-13-877531-1
In the authors’ own words, “Supramolecular chemistry is
the chemistry of systems (supermolecules) made up of molecular components in the same way as molecules are made up
of atoms.. . Supramolecular photochemistry concerns the
control and tuning of the excited state properties of these
molecular components and the study of their intercomponent processes.. . It can be profitably used to make progress
towards the understanding of photobiological processes and
the design of artificial systems capable of performing useful
light-induced functions.” Their stated goal is to illustrate the
fundamental concepts of this field and to review and discuss
some important results and possible applications.
The book is divided into 12 chapters. After an introduction (1. Scope and Limitations) the chapters 2. Principles of
Molecular Photochemistry, 3. Supramolecular Properties,
VerlagsgesellschaftnrbH, W-6940 Weinheim, 1992
and 4. Control and Tuning of Excited-State Properties of
Molecular Components provide a basic but sufficient knowledge of the photophysical concepts needed later. Among the
topics are a discussion of potential energy surfaces and a
concise introduction to the Marcus theory of electron transfer. They are no substitute for one of the more comprehensive monographs on photochemistry but no such attempt is
The following chapters are based on the way in which the
molecular components are held together and/or interact with
one another: 5. Covalently-Linked Systems: Photoinduced
Electron Transfer, and 6. Covalently-Linked Systems: Electronic Energy Transfer. These recapitulate and give further
details of the underlying physics, as well as numerous experimental examples. The section on electron transfer is very
informative, whereas some aspects of electronic energy
transfer remain somewhat sketchy. In both chapters figures
with experimental data on the distance dependence of each
process would be helpful.
Chapter 7. Structural Changes in Photoflexible Systems
deals with photoinduced isomerizations of TICT-compounds, stilbenes, spiropyrans and azobenzene-containing
molecules. Incorporation of these functional units in crown
ethers and other multidentate ligands enables light-induced
changes of the complexating properties of these systems.
Chapters 8. Ion Pairs, and 9. Electron Donor-Acceptor
Complexes and Exciplexes give short introductions to
charge-transfer absorption and emission properties and their
relationship to thermal charge transfer processes, as well as
dynamic and static quenching in these systems.
The following chapters 10. Host-Guest Systems (comprising crown ethers, macrocycles and cyclodextrin inclusion
compounds), and 11. Other Systems (cage ligands, catenanes, and related systems) again deal predominantly with
complexation of metal ions by these structures for the control of their excited state properties.
Chapter 12. Photochemical Molecular Devices finally develops a very illustrative, conceptual framework of how the
systems in earlier chapters can be utilized to design more
complex structures with specific photochemical functions
and proposes possible experimental realizations.
In style and content the book is partly textbook and partly
review article of recent work up to early 1990. Organic systems and systems based on metal complexes are extensively
discussed, with the latter in considerably more detail, probably reflecting the authors’ own predilection and very extensive work in this field. Occasionally too great an effort is
made to present variety and structural differences of many
systems instead of focusing on common mechanisms and
concepts. The emphasis is on systems with a small number of
discrete molecular components. More complex materials
such as polymers, liquid crystals, semiconductors, micelles,
and films are explicitly omitted. In fact, much of the material
would not necessarily be classified as supramolecular, but as
building blocks of larger supramolecular systems. The photochemistry is almost exclusively reversible; irreversible
chemical change in general constitutes undesirable photochemical degradation. In this sense, the book deals predominantly with what one might call elementary processes of
supramolecular photophysics.
Taken as a whole the selection of the material is a sensible
one and the discussion comes to the point. It emphasizes the
interdisciplinary nature of the subject, linking organic, inorganic, and physical chemistry, and the close relationship between molecular structure and photophysical function.
Great effort seems to have been made to make the text
comprehensible for the nonspecialist. Readability is facilitat-
Angew. Chem. In!. Ed. Engl. 31 (1992) N o . 1
ed by a large number of illustrative figures, energy-level diagrams, numerous references and cross references, and extensive author and subject indexes. The book presents basic
physical concepts in simple terms with little formalism and
numerous experimental examples not easily found elsewhere
in such breadth. As such, it provides an interesting and comprehensible introduction for the newcomer to this fascinating field and a valuable source of information for the specialist. However, the readership the book deserves could be
limited by its prohibitive price.
Hans Heitele
Institut fur Physikalische und Theoretische Chemie
der Technischen Universitat Miinchen,
Garching (FRG)
The Chemistry of Enols. (Series: The Chemistry of Functional Groups; Series editor: s.Patai). Volume editor: Z . Rappoport. Wiley, Chichester, 1990. xvi, 823 pp., hardcover
€ 195.00.-ISBN 0-471-91720-6
The addition to the Patai series of a volume treating enols
as a functional group in its own right is clearly warranted by
the revolutionary recent advances achieved in the direct
investigation of enol chemistry. The editor of this volume
has succeeded in engaging leading proponents of recent
developments, thus providing a highly competent and informative account of all the aspects usually covered in the series, namely preparation, structure, and reactivity. Personal
views given by the individual authors provide a vivid presentation of a lively research area from different standpoints. As
a consequence, there is some reiteration of material in different chapters, but, overall, the editor and authors have
achieved a consistent and comprehensive presentation of the
chemistry of enols. Literature coverage is up to 1988 (in part
1989)and contains nearly 2500 references as well as extensive
author and subject indexes providing easy access to up-todate information. A majority of the references cited are from
the last decade, but important early work starting from
Erlenmeyer’s first contribution to enol chemistry in 1875 is
also included. The chemistry of enolates and enol ethers is
deliberately excluded.
Chapter 1 on “Theoretical Calculations” by Y Apeloig
provides an exemplary description of the fruitful interactions
between state-of-the-art theoretical methods and current experimental research. In Chapter 2 J. P. Guthrie derives increments for the Benson group additivity scheme from the
presently available data, and shows how reliably these allow
one to estimate thermodynamic parameters of enols. Chapter 3, “The Chemistry of Ionized Enols in the Gas Phase” by
F. TureEek, discusses the reversal of keto-enol equilibria in
radical cations. In Chapter 4 on “NMR, IR, Conformation
and Hydrogen Bonding” by B. Floris the emphasis is on
systems with substantial equilibrium concentrations of two
or more tautomers; the chapter includes a comprehensive
compilation of spectral data as well as studies of the effects
of solvent, substituents and temperature on equilibria. In
Chapter 5 methods for generating unstable enols in pure
form or in higher than equilibrium concentrations are presented by B. Capon. In Chapter 6 reliable keto-enol equilibrium constants are compiled by J. Toullec, and the merits
and limitations of various methods for determining these
data are critically reviewed. Old and new insight into the
kinetics and mechanism of enolization and ketonization is
reviewed by J. R. Keefe and A. J. Kresge (Chapter 7). Ernphasis is laid on new developments in monitoring ketonizaAngew. Chem. Inl. Ed. Engl. 31 (1992) No.1
tion reactions in aqueous solution, general-acid and generalbase catalysis, isotope effects, and the pathways of the “uncatalyzed” reactions in protic solvents. Isolable and relatively stable simple enols are discussed by H. Hart, Z.
Rappoport and S. E. Biali in Chapter 8. As “simple” enols
they consider those lacking stabilizing functional groups
such as CO in the P-position, in particular the kinetically
stabilized aryl-substituted enols of the type studied by Fuson
in the early forties. Chapter 9 on “Photochemical Reactions
Involving Enols” by A. C. Weedon covers the numerous reactions which lead to the formation of enols as primary
products, as well as the photoreactions of enols themselves.
In Chapter 10 the scarce experimental data on enols of carboxylic acids and esters are reviewed by A. F. Hegarty and P.
O’Neill. In “The Biochemistry of Enols” (Chapter 11) J. P.
Richard focusses on the biochemical reactions of carbonyl
compounds which proceed through enol or enolate reaction intermediates, excluding reactions of the stable enol
Vitamin C. Unstable tautomers can sometimes be stabilized
by complexation; the properties of transition metal-enol
complexes are covered by D. Milstein in Chapter 12
“Organometallic Chemistry of Enols”. Experimental data
on “Structural Chemistry”, mainly from single crystal X-ray
measurements on isolable enols, are compiled and discussed
by G. Gilli and V. Bertolasi in Chapter 13.
The Patai series needs no recommendation as an indispensable source of comprehensive, critical and up-to-date
information. It is clearly a must for any chemical library.
Unfortunately this situation is being exploited by the publishers: the astronomical price of this volume will discourage
most researchers from purchasing their own copy.
Jakob Wirz
Institut fur Physikalische Chemie
der Universitat Base1 (Switzerland)
Synthesis of Lanthanide and Actinide Compounds. Edited by
G. Meyer and L. R. Morss. Kluwer Academic Publishers,
Dordrecht, 1991. xvi, 367 pp., hardcover HFI 220.00.ISBN 0-7923-1018-7
This compendium of invited reviews is the second in a
series of “Topics in $Element Chemistry” edited by Shyama
P. Shinha, the first having appeared some six years ago,
entitled “Americium and Curium Chemistry and Technology”, edited by Edelstein, Navratil, and Schulz. Meyer and
Morss have assembled an outstanding array of contributions
from several of the more noteworthy contemporaries in the
area of synthesis off-element compounds. As they observe in
their Preface, “The history of the rare earths has entered its
third century ;transuranium elements are now a half century
old”, so we cannot expect contributions from all ofthe major
players in f-element chemistry. The fourteen contributions
do, however, contain over 1400 citations that do well to encompass much of the previous work. The goal of the editors
and authors to compile a review of “tried and true” synthetic
techniques has been achieved. Since no single volume of
synthetic reviews can ever be complete, we should anxiously
await the next volume. What follows are some brief comments on each of the fourteen sections.
John Haschke of Rockwell International presents a very
detailed synopsis of Actinide Hydride synthesis in which he
includes an extensive review of kinetics. An additional section concerning the safe handling of hydrides and reduced
actinides was a welcome sight. So often in the literature we
neglect the “obvious” safety concerns. A very detailed sec-
Verlugsgesellschuft mbH, W-6940 Weinheim. 1992
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