Macrocycles as Ion Pair Receptors

Abstract

Cation and anion recognition have both played central roles in the development of supramolecular chemistry. Much of the associated research has focused on the development of receptors for individual cations or anions, as well as their applications in different areas. Rarely is complexation of the counterions considered. In contrast, ion pair recognition chemistry, emerging from cation and anion coordination chemistry, is a specific research field where co-complexation of both anions and cations, so-called ion pairs, is the center of focus. Systems used for the purpose, known as ion pair receptors, are typically di-or polytopic hosts that contain recognition sites for both cations and anions and which permit the concurrent binding of multiple ions. The field of ion pair recognition has blossomed during the past decades. Several smaller reviews on the topic were published roughly 5 years ago. They provided a summary of synthetic progress and detailed the various limiting ion recognition modes displayed by both acyclic and macrocyclic ion pair receptors known at the time. The present review is designed to provide a comprehensive and up-to-date overview of the chemistry of macrocycle-based ion pair receptors. We specifically focus on the relationship between structure and ion pair recognition, as well as applications of ion pair receptors in sensor development, cation and anion extraction, ion transport, and logic gate construction. CONTENTS 3.4.

Allosteric Recognition of Homomeric and Heteromeric Pairs of Monosaccharides by a Foldamer Capsule

“…Theh ost-mediated allosteric communication between two guests of identical size that differ by two stereogenic centers,x ylose and arabinose,w ithout contact between them appears to be unique.Usually,ahost meant to bind two different guests would be designed with two different binding sites,f or example,t ob ind an ion pair. [19] Alternatively,symmetrical hosts have been shown to bind to heteromeric pairs of guests when the first guest occupies more than half of the space available,l eaving room only for asmaller guest. [14] At last, we challenged the stereoselectivity of the complexation of both 3 and 4 by (2) 2 to draw ap arallel with the mutual exclusion of d-3 and l-3 mentioned above.T he addition of d-3 to (2) 2 '(d-4)f irst produced (2) 2 '(d-3;d-4) and then, with al arge excess of d-3,l ed to (2) 2 '(d-3) 2 .I n contrast, the addition of l-3 to (2) 2 '(d-4)did not produce any heteromeric complex.…”

Molecular Recognition of Zwitterions with Artificial Receptors

“…Crown ethers efficiently interact with cations and, depending on the structure, may interact selectively with ammonium ions, particularly with protonated primary amines. Therefore, receptors containing a crown ether fragment plus an additional site for anion recognition have been a useful platform to construct receptors for zwitterionic species …”

“…Therefore, receptors containing a crown ether fragment plus an additional site for anion recognition have been a useful platform to construct receptors for zwitterionic species. [13] Ignacio Alfonso studied Chemistry at the University of Oviedo (Spain), obtaining his PhD at the same University in 1999. After two post-doctoral studies at The Scripps Research Institute in La Jolla (USA, 2000(USA, -2002 and back to the University of Oviedo (2002)(2003)(2004) Several functional groups able to interact with the anionic moiety of zwitterions have been used in order to synthesize ditopic receptors.…”

“…Urea modified β-cyclodextrins described by Jurczack(12) for the recognition of amino acids and bis-β-cyclodextrins developed in the early 90's by Breslow(13).…”

Counterion‐Trapped‐Molecules: From High Polarity and Enriched IR Spectra to Induced Isomerization

“…Most of the above systems can be viewed as smaller counterparts of macrocycles hosting, in particular, inorganic ion-pairs, as reviewed very recently. [17] For instance, calix [4] pyrrole and hexacyclen as receptors of both alkali and halogen ion pairs [18,19] represent structural extensions of the above systems.…”