Chapter 4 Synthesis of molecular tweezers and clips by the use of a molecular lego set and their supramolecular functions

Abstract

This chapter discusses the synthesis of molecular tweezers and clips by the use of a molecular Lego set and their supramolecular functions. Molecular tweezers and clips systems serve as host molecules binding guest molecules by multiple aromatic interactions (π–π, CH–π and cation–π interactions). Aromatic interactions are important factors that determine the structures and properties of many higher organized chemical and biological systems. Examples are the base stacking in DNA and the protein folding caused by phenylalanine and other aromatic amino acid side chain interactions. The preference of the edge-to-face over the face-to-face orientation of two benzene rings, as it is found in the crystal structure of benzene or in the protein structures mentioned above, can be explained with a simple electrostatic model for benzene consisting of a positively charged cr framework sandwiched between two clouds of π electron density. Quantum mechanical calculations predict a displaced face-to-face orientation slightly more stable than the edge-to-face configuration.