ISSN 0036-8075

22 February 1985Volume 227, No. 4689

Chemistry Issue

Edited by Philip H. Abelson

LETTERS Pentagon Decision-Making: J. F. Ahearne; Global Energy Study: B. Keepin andB. Wynne; Development and the Market Process: H. D. Greyber;C. D. Denman; J. F. Butler; G. Piel .......... ........................... 838

EDITORIAL Federal Support for Chemistry .............. ................................ 847

ARTICLES Supramolecular Chemistry: Receptors, Catalysts, and Carriers: J.-M. Lehn ...... 849

[2 + 2] Photocycloadditions in the Synthesis of Chiral Molecules:S. L. Schreiber ......................................................... 857

Gas-Phase Ion Chemistry: P. B. Comita and J. I. Brauman .863

Mechanisms of Coenzyme B12-Dependent Rearrangements: J. Halpern.869Toward a Coherent Theory of Chemisorption: E. Shustorovich and

R. C. Baetzold .876

Electrically Conductive Metallomacrocyclic Assemblies: T. J. Marks .881

Laser Probing of Chemical Reaction Dynamics: S. R. L ene.889

Understanding Molecular Dynamics Quantum-State by Quantum-State:W. D. Lawrance, C. B. Moore, H. Petek .895

Surface Science and Catalysis: G. A. Somorjai .902

Sculpting Horizons in Organic Chemistry: B. M. Trost .908

Theoretical Chemistry Comes Alive: Full Partner with Experiment:W.A. GoddardIII .917

NEWS AND COMMENT

RESEARCH NEWS

"Nuclear Winter" Feels Budgetary Chill .....................................

Carnegie Launches Education Forum ........................................

A Push for European Patent Reform .........................................

Briefing: Brown Loses Bid to Head Space Subcommittee; Herrington Confirmedas Energy Secretary; Germany Announces Plans for Reprocessing Plant;Comings and Goings ...................................................

Could an Asteroid Be a Comet in Disguise?..................................Changing Bits to Magnetic Blips.............................................

"Anxiety Peptide" Found in Brain...........................................

BOOK REVIEWS The lUogic of American Nuclear Strategy, reviewed by R. J. Lieber; Atlas ofLithological-Paleogeographical Maps of the World, W. T. Holser; Reversalsof the Earth's Magnetic Field, A. Cox; The Interferon Crusade,R. A. Rettig; Books Received ...........................................

REPORTS High-Resolution Stratigraphy with Strontium Isotopes: D. J. DePaolo andB. L. Ingram ..........................................................

Chromosomal Locations of the Murine T-Cell Receptor Alpha-Chain Geneand the T-Cell Gamma Gene: D. M. Kranz et al. .........................

Molecular Structure of Troponin C from Chicken Skeletal Muscle at 3-AngstromResolution: M. Sundaralingam et al. ....................................

Effects on Trichinella spiralis of Host Responses to Purified Antigens:D. S. Silberstein and D. D. Despommier .................................

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COVER

Chemical transformations mediated bylight (hv) provide photoproducts thatcan be employed in organic synthesis.The four-membered rings impart spe-cial properties on these compoundsthat facilitate their conversion to a vari-ety of target systems, including mole-cules with important biological proper-ties. See page 857. [Illustration byChristine M. Hoyeyda]

22 February 1985, Volume 227, Number 4689

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SCIENCE

*al Support for Chemistryg the past 2 years a substantial fraction of leading chemists has beened with George Pimentel of Berkeley in the preparation of aResearch Council report detailing some of the progress, triumphs,Is of their discipline. Much has happened in the two decades sinceNRC chemistry report. Chemistry retains a historic role as aIds of the sciences and a tremendous source of practical applica-ut new capabilities and new tools have been added. A host ofI analytical instruments has become available. Theoretical chemis-part based on the Schrodinger wave equation, is increasinglyive. Computer-produced three-dimensional displays of moleculesviding chemists with sharper insights into the geometries andons of molecules. Many of the approaches of physics are now beingto obtain data on excited states of molecules and reaction mecha-

;ummer, before the choice of the new editor and the selection ofauman as Deputy Editor for Physical Sciences, the decision wasmark the occasion of the issuance of the Pimentel Report with theion of a number of articles in Science. They are being published ine, which anticipates slightly the appearance of the report. Thesample some of the research activities that are now makingry a less empirical and far more powerful discipline than most of ourencountered during their undergraduate and graduate days. A fews from these articles are cited.ular interactions (supramolecular chemistry) are the basis of thepecific processes occurring in biology, such as substrate binding to,me. Recognition of a substrate to a receptor requires both aical fit and binding between the interacting species. In this issue amber of different synthetic molecules are described that have cave-ctures which are capable of selective binding and hence separationar cations and anions. Other synthetic receptors may bind ae, effect a reaction on it, and release the products.articles describe relatively new work on the dynamics of chemicals. Experimental tools include ion beams, mass spectroscopy, ionpnresonance, and lasers. Use of tunable lasers permits selective)n of particular states with photons ranging from infrared to deeplet. One laser may be used to excite a molecule to participate in a; a second may be used to probe the reaction products. Since veryier pulses can be used, the time between excitation and interroga-be less than 10-8 seconds. A fundamental question to be investigat-.hort pulse lasers is the time required for the redistribution oflecular vibrational energy. That is, one excites a particular bond andserves fluorescence from other vibrational states. For the C-Hg motion the time required to transfer energy to other vibrationalis of the order of 100 femtoseconds.ogeneous catalysis plays a crucial role in the production of most1 chemicals. Articles in this issue touch on efforts to achieve aasic understanding of the mechanisms involved. Three factors thatsurface catalysis are the atomic surface structure, an active over-the surface, and the oxidation states of surface atoms. Forthe (111) crystal face of iron produces ammonia from N2 and H2 at

s the rate of the (110) face at 20 atmospheres and 450°C. In thenation of CO over rhodium the yields are predominantly CH4.r, when Rh2O3 was used, oxygenated C2 and C3 compounds wered, including ethanol, acetaldehyde, and propionaldehyde.tant progess is being made in chemistry. In proportion to itsLtion to the advancement of other sciences and its contributions toiomy, chemistry is the most underfunded of all the natural sciences.be hoped that the efforts of Pimentel and his collaborators will bed by a generosity that is merited.-PHILIP H. ABELSON