Page 230 - Academic Press Encyclopedia of Physical Science and Technology 3rd Organic Chemistry

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Encyclopedia of Physical Science and Technology EN011A-543 February 12, 2002 12:40

Organic Macrocycles

J. Ty Redd Reed M. lzatt
Southern Utah University Jerald S. Bradshaw
Brigham Young University

I. Macrocyclic Structure and Metal Cation
Complexation
II. Complexation of Organic Cations
III. Complexation of Anions and Neutral Molecules
IV. Applications of Macrocyclic Ligands
V. Synthesis of Macrocyclic Compounds

GLOSSARY Macrocycle Cyclic ligand large enough to accommodate
a substrate in the central cavity.
Binding constant Equilibrium constant associated with Macrocyclic effect Extra stability of complexes of cyclic
a reaction in which a ligand binds to a substrate. ligands over those of analogous acyclic ligands.
Biomimetic That which mimics biological systems. Molecular recognition Ability of molecules to discern
Calixarene Class of compounds consisting of a ring of one another through molecular interactions that conse-
phenol moities connected by methylene bridges. quently form stable organized structures.
Crown ether Cyclic organic compound consisting of a Self-assembly A spontaneous organization of molecules
number of connecting ethylene oxide units. or objects into stable aggregates by noncovalent forces.
Cryptand Organic compound consisting of two or more Spherand Typeofmacrocycle(seecompound11,Fig.1).
bridges connecting nitrogen atoms to give multiple Supramolecular chemistry A discipline that exploits
rings. fundamental concepts such as self-assembly, organi-
Cyclic polyether See crown ether. zation, and replication.
Cyclodextrin Class of cyclic polysaccharide com-
pounds.
Enantiomeric recognition Differentiation of one enan- MACROCYCLEScomprise a large group of heterocyclic
tiomer of the guest from the other by a chiral host. organic compounds that can bind cationic, anionic, or neu-
Guest Chemical species that can be trapped by a host tral substrates by entrapment within the cavity created by
compound. the macrocyclic structure. The selectivity of the macrocy-
Host Compound that can trap a guest species. cle for certain chemical species is a function of many pa-
Macrobicyclic effect Extra stability of complexes of rameters, an important one being the match between sub-
macrobicyclic (cryptands) over those of crown ethers. strate size and macrocycle cavity size. When the substrate

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