Helical Anion Foldamers in Solution

Abstract

Using anions to induce molecular structure is a rapidly growing area of dynamic and switchable supramolecular chemistry. The emphasis of this review is on helical anion foldamers in solution, and many of the beautiful complexes described herein are accentuated by their crystal structures. Anion foldamers are defined as single- or multistrand complexesoften helicalthat incorporate one or more anions. The review begins by discussing foldamer structure and nomenclature and follows with discourse on the anions which are employed. Recent advances in functional foldamers that bind a single anion are examined, including: induced chirality, stimuli-responsive dynamics, fluorescence changes, organocatalysis, anion transport, and halogen bonding. The review then inspects multianion foldamers, and this section is organized by the number of strands within the foldamerfrom single- to triple-strand foldamers. Finally, the review is punctuated by recent hydrogen- and halogen-bonding triple-strand anion foldamers.

Ground- and excited-state dynamic control of an anion receptor by hydrostatic pressure

“…64 Foldamers consist of rather exible strands and form well-organized supramolecular structures with neutral and/or anionic guest molecules, and thus may be considered as an induced-t type receptor. [65][66][67] In fact, Moore and Drickamer et al demonstrated that binding constants (K) of the piperazine or terpene guest upon interactions with oligo (m-phenylene ethynylene) foldamers in polymer matrixes decreased with increasing pressure of up to 65 000 MPa, i.e., positive reaction volumes (DV > 0), revealed by the diamond anvil cell technique. 68 Nevertheless, solution-state molecular recognition behavior of foldamers under hydrostatic pressures has not been examined in any detail, and hence, is still a challenge for the further evolution of supramolecular chemistry.…”

Anion Templated Supramolecular Structures Assembled using 1,2,3‐Triazole and Triazolium motifs

“…These systems are dynamic and typically exist in an equilibrium of the folded and unfolded structure [20] . Anion templated foldamers have grown rapidly into an exciting field, and interested readers are encouraged to read the recent and comprehensive review by Berryman and co‐workers [21] …”

Helix-Like Receptors for Perrhenate Recognition Forming Hydrogen Bonds with All Four Oxygen Atoms

“…We have proposed that the introduction of a helix-forming subunit together with additional two binding sites would allow us to bind all four oxygen atoms of the perrhenate anion. Recent analysis of the literature on helical anion foldamers shows that this kind of synthetic receptors demonstrates high selectivity even in an aqueous medium [46]. Preliminary quantum chemical modeling of the receptor structures revealed that dicarboxamide derivatives of ferrocene, m-xylylene, and diphenylacetylene are promising helix-forming subunits.…”

“…demonstrates high selectivity even in an aqueous medium [46]. Preliminary quantum chemical modeling of the receptor structures revealed that dicarboxamide derivatives of ferrocene, m-xylylene, and diphenylacetylene are promising helix-forming subunits.…”