Molecular squares and boxes

8 Fujita, M., Tominaga, M., Hori, A. and Therrien, B., Coordination assemblies from a Pd(II)-cornered square 

The work of Thomas et al. was preceded by the formation of a range of related molecular squares and triangles such as Fujita s molecular square (10.10), which is able to function as a solution host for aromatic guests such as naphthalene with a binding constant, Kn of 1800 M Rigid spacers (edges) 

Resorcarene hexamers bridged either by 24 Cu(ll) ions or 12 Ga(Ill) ions have also been prepared. These compounds are closely analogous to hydrogen-bonded resorcarene and pyrogallolarene hexamers (indeed the metal-bridged compounds can be prepared by substitution of 2H+ for Cu +) and we will look at these systems as a whole in Section 10.6.3. 

Loss of a ligand to form a square pyramidal, five-coordinate transition state (or possibly an intermediate if the compound is at a local minimum on the energy curve)  

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A chiral bisphosphine such as 2,2 -h -(diphenylphosphino)-l,F-binaphthyl (BINAP) has been extensively used as a chiral chelator in asymmetric catalysis. When Stang et al. reacted the chiral metal complex 42 with 40, they synthesized a square box (Figure 25) and asymmetric induction was observed [79,82] with the formation of an excess of one of the preferred diastereoisomers as measured by NMR spectroscopy. The same reaction has been carried out with 42 and 6is-4-(4 -pyridyl)phenyl)iodonium triflate, but in this case the diaza ligands of the iodonium species possess rotational symmetry about their linkages. Consequently, the optical activity of the molecular squares obtained is due exclusively to the chiral transition metal auxiliary BINAP. 

Fluorescence Sensing of Anions, p. 566 Guanidium-Based Anion Receptors, p. (575 Halogen Bonding, p. 628 Macrocyclic Synthesis, p. 830 Molecular Squares, Boxes, and Cubes, p. 909 Naked Anion Effect, p. 939 Organometallic Anion Receptors, p. 1006 Rotaxanes and Pseudorotaxanes, p. 1194 Self-Assembly Definition and Kinetic and Thermodynamic Considerations, p. 1248 The Template Effect, p. 1493... 

Ion Channels and Their Models, p. 742 Ion-Selective Electrodes, p. 747 The Lock and Key Principle, p. 809 Molecular Squares, Boxes, and Cubes, p. 909... 

Molecular Squares, Boxes, arid Cubes, p. 909 71-71 Stacking Theory and Scope, p. 1076 Preorganization and Complementarity, p. 1158 Pyrrole- and Polypyrrole-Based Anion Receptor-s. p. 1176 Rotaxanes arid Pseudorotaxanes, p. 1194 Self-Assernhling Catenanes, p. 1240 Siderophores, p. 1278 Spherands, p. 1344... 

Concepts in Crystal Engineering, p. 319 Crystal Engineering with Hydrogen Bonds, p. 357 Crystal Structure Prediction, p. 371 Cfystalline Microporous Silicas, p. 380 Dye Inclusion Crystals, p. 497 Hofmann-Type Clathrates, p. 645 Mineralomimetic Structures, p. 868 Molecular Squares, Boxes, and Cubes, p. 909 Organic Zeolites, p. 996 Soft/Smart Materials, p. 1302... 

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