Anion receptor chemistry: Highlights from 2016

Abstract

This article marks the 20 th year of coverage of anion receptor chemistry by this series of reviews. In the first review, published in Coordination Chemistry Reviews in 2000 (and covering highlights in anion coordination and anion directed assembly in 1997 and 1998),[1] it was noted that "Anion coordination has received little attention over the last 30 years when compared to that devoted to the coordination chemistry of cations." Now as we look back over the last 50 years we see that this has changed and that many real world applications for anion complexation have emerged.[2] Although this review has moved between publications over the last two decades;[1, 3-11]-it is appropriate for it return to Coordination Chemistry Reviews to mark both this milestone and the special issue devoted to Coordination Chemistry in Australia. 2. Fundamental studies This section covers the development of new receptors and understanding the fundamentals of anion interactions, ranging from classic hydrogen-bond systems to more exotic halogen and chalcogen bond-based receptors. In 2016, we have seen examples of anion receptors that advance our understanding of aromatic, hydrophobic and ion-pair interactions, and the development of photo-switchable receptors and multivalent systems. 2.1. Hydrogen-bond based receptors A number of groups have exploited C-H hydrogen bonds for the recognition of anions. Amendola and coworkers [12] reported the C-H hydrogen bonding receptor 1•(PF6)3 based on a tripodal 1,3,5-trimethylbenzene scaffold and incorporating imidazolium and 2,3,4,5-tetrafluorobenzene moieties as C-H hydrogen-bond donors. Proton NMR titrations in CD3CN and

Configurational Selection in Azobenzene‐Based Supramolecular Systems Through Dual‐Stimuli Processes

“…Exploiting the reversible complexation of anions, one could imagine using the binding event as allosteric stimulus to modify either the thermodynamic and/or the kinetic of the E / Z isomerization process. Despite the large body of research on supramolecular recognition of anions, the examples of photoregulated anion receptors are scarcer with respect to those designed for cations and often incorporate different switches than those deriving from azobenzenes …”

Steroid-Based Supramolecular Systems and their Biomedical Applications: Biomolecular Recognition and Transportation

“…For the recognition of aromatic molecules, the arms of the molecular clefts/tweezers were generally designated to be aromatic and with special geometrical arrangements. Taking the advantages of low cost, head-tail-modifiable molecular groups, rigidity, chemically different hydroxyl groups, unique amphiphilicity, and natural chiral microenvironment, bile acids and their derivatives are mostly employed to construct steroid-based molecular clefts/tweezers [17].…”

“…For the steroid-based molecular clefts/tweezers toward anion recognition, acidic amide groups (such as NH in ureas or thioureas) were always used to achieve higher affinities [17]. In this context, Davis et al constructed anion receptor by placing squaramide groups in axial positions at the hydroxyl groups of steroid (cholic acid) skeleton, which could fix the NH groups on squaramide at certain locations for cooperatively bind anions (Figure 4).…”

Chemiresistors for the Real‐Time Wireless Detection of Anions

“…Anion recognition and sensing are of increasing importance in healthcare, biology, environment, and military applications . In particular, real‐time analysis of a trace amount of specific anions is crucial to the monitoring of the physical and metabolic states of biological systems.…”