Synthesis of Pillar[6]arenes and Their Host-Guest Complexes

Pillar[n]arenes are a fast-growing research topic in supramolecular chemistry. Originally the focus was predominantly on pillar[5]arenes; however, now more and more studies on pillar[6]arenes are being performed. The ability and selectivity of host-guest complexations depend strongly on the size of the inner cavities of these macrocycles. New results have stimulated us to compile the synthetic entries and the complexations of pillar[6]arenes with large cylindric cavities that offer space for many different guest molecules. 1 Introduction 2 Preparation of Pillar[6]arenes 2.1 Pillar[6]arenes by Macrocyclization Reactions 2.2 Hydroxypillar[6]arenes through Ether Cleavage 2.3 Hydroxypillar[6]arenes by Redox Reactions 2.4 Alkylation of Hydroxypillar[6]arenes 2.5 Pillar[6]arenes Obtained from Preformed Pillar[6]arenes by Transformation of Alkoxy Chains 3 Structure of Pillar[6]arenes in the Crystalline State and in Solution 3.1 Dodecaalkoxypillar[6]arenes 3.2 Perhydroxypillar[6]arenes 4 Generation of Complexes 4.1 Inclusion of Guest Molecules 4.2 Complexes of Ammonium Compounds 4.3 Complexes of Pyridinium Compounds 4.4 Complexes of Other Cations 4.5 Complexes of Electroneutral Guest Molecules 4.6 Complexes of Anions 4.7 Self-Assembly by Complexation 4.8 Binding on Metal Surfaces 4.9 Capture of Gases and Vapors 5 Conclusion