1. P. Knops, N. Sendhoff, H.-B. Mekelburger, F. Voegtle, Bonn/FRG HighDilution Reactions - New Synthetic Applications 2. A. Ostrowicki, E. Koepp, F. Voegtle, Bonn/FRG The "Cesium Effect": Syntheses of Medio- and Macrocyclic Compounds 3. J. Dohm, F. Voegtle, Bonn/FRG Synthesis of (Strained) Macrocycles by Sulfone Pyrolysis 4. Q. Meng, M. Hesse, Zurich/Switzerland Ring Closure Methods in the Synthesis of Macrocyclic Natural Products 5. J.L. Sessler, A.K. Burrell, Austin, TX/USA Expanded Porphyrins

1. F.H. Kohnke, J. Mathias, J.F. Stoddart: Substrate-Directed Synthesis: The Rapid Assembly of Novel Macropolycyclic Structures via Stereoregular Diels-Alder Oligomerizations 2. S.C. Zimmerman: Rigid Molecular Tweezers as Hosts for the Complexation of Neutral Guests 3. A. Collet, J.-P. Dutasta, B. Lozach, J. Canceill: Cyclotriveratrylenes and Cryptophanes: Their Synthesis and Applications to Host-Guest Chemistry and to the Design of New Materials 4. J.-C. Chambron, Ch.D. Dietrich-Buchecker, S. Misumi: From Classical Chirality to Topologically Chiral Catenands and Knots 5. S. Misumi: Recognitory Coloration ofCations with Chromoacerands 6. D.A. Tomalia, H.D. Durst: GenealogicallyDirected Synthesis: Starburst/Cascade Dendrimers and Hyperbranched Structures

Considering the high level of our knowledge concerning covalent bond formation in the organic chemistry of molecules, our understanding of the principles involved in organic solid design is almost in its infancy. While chemists today are able to synthesize organic molecules of very high complexity using sophisticated methods of preparation, they lack general approaches enabling them to reliably predict organic crystalline or solid structures from molecular descriptors - no matter how simple they are. On the other hand, nearly all the organic matter surrounding us is not in the single-molecule state but aggregated and condensed to form liquid or solid molecular assemblages and structural arrays giving rise to the appearances and properties of organic compounds we usually observe. Obviously, the electrical, optical or magnetic properties of solid organic materials that are important requirements for future technologies and high-tech applications, as well as the stability and solubility behavior of a medicament depend on the structure of the molecule and the intramolecular forces, but even more decisively on the intermolecular forces, i. e. the packing structure of the molecules to which a general approach is lacking. This situation concerned ]. Maddox some years ago to such a degree that he described it as "one of the continuing scandals in the physical sciences" [see (1998) Nature 335:201; see also Ball, P. (1996) Nature 381:648]. The problem of predicting organic solid and crystal structures is very dif- cult.

Considering the high level of our knowledge concerning covalent bond formation in the organic chemistry of molecules, our understanding of the principles involved in organic solid design is almost in its infancy. While chemists today are able to synthesize organic molecules of very high complexity using sophisticated methods of preparation, they lack general approaches enabling them to reliably predict organic crystalline or solid structures from molecular descriptors - no matter how simple they are. On the other hand, nearly all the organic matter surrounding us is not in the single-molecule state but aggregated and condensed to form liquid or solid molecular assemblages and structural arrays giving rise to the appearances and properties of organic compounds we usually observe. Obviously, the electrical, optical or magnetic properties of solid organic materials that are important requirements for future technologies and high-tech applications, as well as the stability and solubility behavior of a medicament depend on the structure of the molecule and the intramolecular forces, but even more decisively on the intermolecular forces, i. e. the packing structure of the molecules to which a general approach is lacking. This situation concerned ]. Maddox some years ago to such a degree that he described it as "one of the continuing scandals in the physical sciences" [see (1998) Nature 335:201; see also Ball, P. (1996) Nature 381:648]. The problem of predicting organic solid and crystal structures is very dif- cult.

1. F.H. Kohnke, J. Mathias, J.F. Stoddart: Substrate-Directed Synthesis: The Rapid Assembly of Novel Macropolycyclic Structures via Stereoregular Diels-Alder Oligomerizations 2. S.C. Zimmerman: Rigid Molecular Tweezers as Hosts for the Complexation of Neutral Guests 3. A. Collet, J.-P. Dutasta, B. Lozach, J. Canceill: Cyclotriveratrylenes and Cryptophanes: Their Synthesis and Applications to Host-Guest Chemistry and to the Design of New Materials 4. J.-C. Chambron, Ch.D. Dietrich-Buchecker, S. Misumi: From Classical Chirality to Topologically Chiral Catenands and Knots 5. S. Misumi: Recognitory Coloration of Cations with Chromoacerands 6. D.A. Tomalia, H.D. Durst: Genealogically Directed Synthesis: Starburst/Cascade Dendrimers and Hyperbranched Structures