Function-Oriented Molecular Design: Cryptand

This chapter mainly describes the structures, major applications, and synthesis of cryptands and related compounds. It summaries eleven types of cryptands that are classified in the shape or function. The chapter introduces Lehn's pioneering cryptands and carbon-bridge heads cryptands. It also describes phenolic OH and pyridine-containing cryptands, as well as photoresponsive cryptand. The chapter discusses three types of cryptands that can be used as photoluminescent sensors, that is, fluorescent photo-induced electron transfer (PET), fluorescent photo-induced charge transfer (PCT), and fluorescence resonance energy transfer (FRET). It explains these cryptands as anion receptors. The chapter also discusses proton sponges and ansa-type proton sponges. These new cryptands form supramolecular structures such as pseudorotaxane-like inclusion complex with organic cations. The chapter focuses on the crown ether based cryptands and cages. The chapter also explains the boron-containing cryptands and phosphorus-containing cryptands. It presents some examples of calix[4]arene- and calix[6]arene-based cryptands. Keywords: anion receptors; calixarene; carbon-bridge heads cryptands; crown ether; Lehn's pioneering cryptands; photoluminescent sensors; proton sponges; supramolecular structures