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Intramolecular hydrogen bonding in calixarenes

The construction of a molecular cavity for recognition and catalysis requires either covalent synthesis or intermolecular self-assembly of complementary units. Intramolecular hydrogen bonding is another tool to control the cavity-forming process. When properly positioned within the same molecular structure, hydrogen bonding sites are responsible for the formation, preorganization, and binding ability of the host. The most typical examples from the supramolecular chemistry of calixarenes, the key cavity-containing building blocks, and derived from them receptor molecules are discussed.