Abiotic guanidinium containing receptors for anionic species

In the field of molecular recognition, the guanidinium group has been established as a highly effective functional group in the binding of anionic guests. This moiety has been proven to form a strong interaction with anions through charge pairing and hydrogen bonding in competitive solvent systems. The group also features a high pK(a) value, allowing for its utility over an expansive pH range. As a result of these qualities, the guanidinium group has become ubiquitous in literature involving the design and synthesis of receptor molecules for small target anions. An overview of the inclusion of the guanidinium group within synthetic receptor molecules is presented in this review article. (C) 2002 Elsevier Science B.V. All rights reserved.