Crystal engineers aim to control the way molecules aggregate in the
crystalline phase and are therefore concerned with crystal
structure prediction, polymorphism, and discovering the relative
importance of different types of intermolecular forces and their
influence on molecular structure. In order to design crystal
structures, knowledge of the types, strengths, and nature of
possible intermolecular interactions is essential. Non-covalent
interactions involving p-systems is a theme that is under extensive
investigation as these interactions can be inductors for the
assembly of a vast array of supramolecular architectures.

The Importance of Pi-Interactions in Crystal
Engineeringcovers topics ranging from the identification of
interactions involving p-systems, their impact on molecular and
crystal structure in both organic and metallorganic systems, and
how these interactions might be exploited in the design of new
materials. Specialist reviews are written by internationally
recognized researchers drawn from both academia and industry.

The Importance of Pi-Interactions in Crystal
Engineeringprovides an essential overview of this important
aspect of crystal engineering for both entrants to the field as
well as established practitioners, and for those working in
crystallography, medicinal and pharmaceutical sciences, solid-state
chemistry, physical chemistry, materials and nanotechnology

Edward R. T. Tiekink is the author of The Importance of Pi-Interactions in Crystal Engineering: Frontiers in Crystal Engineering, 2nd Edition, published by Wiley. Julio Zukerman-Schpector is the author of The Importance of Pi-Interactions in Crystal Engineering: Frontiers in Crystal Engineering, 2nd Edition, published by Wiley.

Zusammenfassung
Crystal engineers aim to control the way molecules aggregate in the crystalline phase and are therefore concerned with crystal structure prediction, polymorphism, and discovering the relative importance of different types of intermolecular forces and their influence on molecular structure. In order to design crystal structures, knowledge of the types, strengths, and nature of possible intermolecular interactions is essential. Non-covalent interactions involving p-systems is a theme that is under extensive investigation as these interactions can be inductors for the assembly of a vast array of supramolecular architectures.

The Importance of Pi-Interactions in Crystal Engineeringcovers topics ranging from the identification of interactions involving p-systems, their impact on molecular and crystal structure in both organic and metallorganic systems, and how these interactions might be exploited in the design of new materials. Specialist reviews are written by internationally recognized researchers drawn from both academia and industry.

The Importance of Pi-Interactions in Crystal Engineeringprovides an essential overview of this important aspect of crystal engineering for both entrants to the field as well as established practitioners, and for those working in crystallography, medicinal and pharmaceutical sciences, solid-state chemistry, physical chemistry, materials and nanotechnology

List of Contributors xv

1 The CH/ Hydrogen Bond: Implication in Crystal Engineering 1
Motohiro Nishio, Yoji Umezawa, Hiroko Suezawa and Sei Tsuboyama

1.1 Introduction 1

1.2 Cooperative Effect of the CH/ Hydrogen Bond 7

1.3 CH/ Hydrogen Bonds in Supramolecular Chemistry 14

1.4 Crystallographic Database Analyses 25

1.5 Systematic CSD Analyses of the CH/ Hydrogen Bond 28

1.6 Summary and Outlook 31

2 New Aspects of Aromatic . . . and C-H . . . Interactions in Crystal Engineering 41
Roger Bishop

2.1 Introduction 41

2.2 Three-Dimensional Aromatic Structures 44

2.3 Endo,Endo-Facial Dimers 46

2.4 Multiply Halogenated Heteroaromatic Molecules 49

2.5 Expansion of the Endo,Endo-Facial Dimer 56

2.6 (EF)6 Brick-Like Building Blocks 59

2.7 Other Novel Multiple EdgeFace Assemblies 64

2.8 Other Types of ArylAryl Contacts 68

2.9 Conclusions 75

3 CH. . . and . . . Interactions as Contributors to the Guest Binding in Reversible Inclusion and Encapsulation Complexes 79
Dr. Pablo Ballester and Dr. Shannon M. Biros

3.1 Introduction 79

3.2 Probing AromaticAromatic () Interactions and CH Interactions with Solid-State Structures of Reversible Inclusion and Encapsulation Complexes 83

3.2.1 Inclusion Complexes 83

3.3 Summary and Outlook 104

4 A Rudimentary Method for Classification of ··· Packing Motifs for Aromatic Molecules 109
Leigh Loots and Leonard J. Barbour

4.1 Introduction 109

4.2 Theoretical Models 110

4.3 ··· Interactions 111

4.4 Structure Prediction and Comparisons 113

4.5 ··· Interactions in Heteroaromatic Molecules 113

4.6 ··· Interactions in Cocrystals 119

4.7 Summary 123

5 Conformational Flexibility and Selectivity in HostGuest Systems 125
Nikoletta B. Bathori and Luigi R. Nassimbeni

5.1 Introduction 125

5.2 Selectivity 129

5.3 Concluding Remarks 139

6 Organic -Radicals in the Solid-State: from Localised to Delocalised -Bonding 143
Marc Fourmigue

6.1 Introduction 143

6.2 Molecules for -Radical Formation 144

6.3 Dimers of Radicals versus Radical Dimers (Pimers) 149

6.4 Solid-State Magnetic and Conducting Properties 154

6.5 Conclusions 159

7 ArenePerfluoroarene Interactions in Coordination Architectures 163
Akiko Hori

7.1 Introduction 163

7.2 Background 165

7.3 Guest Recognition by Coordination Networks 169

7.4 Fluorinated Coordination Complexes 172

7.5 Cocrystals of Coordination Complexes 179

7.6 Self-Assembly in Solution 181

7.7 Conclusions 182

8 Halogen. . . Interactions as Important Contributors to Binding Affinity in Medicinal Chemistry 187
Hans Matter, Marc Nazare, and Stefan Gussregen

8.1 Introduction 187

8.2 General Aspects of Halogen Atoms in Medicinal Chemistry 189

8.3 Fluorine: a Unique Halogen Atom 190

8.4 Interactions of Higher Halogen Atoms 196

8.5 Interactions of Higher Halogen Atoms to Aromatic Rings 204

8.6 Conclusions 226

9 Fuzzy Electron-Density Fragments as Building Blocks in Crystal-Engineering Design 233
Paul G. Mezey

9.1 Introduction 233

9.2 A Brief Re...