Title: Soft Materials Constructed Using Calix[4]pyrrole- and “Texas-Sized” Box-Based Anion Receptors

Abstract

We present that soft materials have received considerable attention from supramolecular chemists and material scientists alike. This interest reflects the advantages provided by their soft, flexible nature and the convenience of the molecular self-assembly that underlies their preparation. Common soft supramolecular materials include polymeric gels, supramolecular polymers, nanoaggregates, and membranes. Polymeric gels are solidlike networks of cross-linked polymer chains. Supramolecular polymers contain repeat units connected through reversible non-covalent bonds. Nanoaggregates are formed as a result of hydrophobic interactions involving amphiphilic building blocks. Because of the presence of non-covalent interactions, supramolecular soft materials typically display stimuli-responsive or adaptive features. Various macrocyclic hosts, such as cyclodextrins, crown ethers, calixarenes, cucurbiturils, and pillararenes, and many classic non-covalent interactions have been harnessed to construct supramolecular soft materials. Only recently has anion binding been used as the underlying recognition motif. Anions are ubiquitous in the natural world. Their importance has inspired efforts to achieve good anion binding and to exploit anion recognition in a number of fields, including extraction, transport, sensing, and catalysis. Most of this effort has involved the use of stand-alone anion receptors. On the other hand, soft materials with anion recognition features could lead to new macromolecular systems of interest in themore » context of many application areas. In this Account, we summarize the latest efforts from our laboratory to prepare supramolecular soft materials, including polymeric gels, supramolecular polymers, and nanoaggregates, with bona fide anion recognition features. Two anion receptor systems, namely, calix[4]pyrroles (C4Ps) and a tetraimidazolium macrocycle known as the “Texas-sized” molecular box (TxSB), have been used for this purpose. To date, TxSB-based hydrogels have been utilized to capture anions from water and for coded information applications; C4P-based organic polymeric gels have been used to extract dianions from aqueous source phases and for the on-site detection of chloride anions. Polymers containing C4P and TxSB anion recognition subunits typically display responsive features and can be modified through application of appropriately chosen external stimuli. For instance, nanoaggregates may be formed as a result of the hydrophobic interactions of C4P- and TxSB-based amphiphiles. The resulting aggregates were found to mimic the structural evolution of organelles and could be used as effective anion and ion pair extractants. This Account summarizes progress to date while underscoring potential opportunities associated with combining anion recognition and soft materials chemistry. Finally, the hope is to stimulate further advances in broad areas, including polymer science, supramolecular chemistry, biology, materials research, and information storage.« less

Authors:

Ji, Xiaofan ^[1]; Chi, Xiaodong ^[1]; Ahmed, Mehroz ^[1]; Long, Lingliang  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-3589-2075"

Sessler, Jonathan L.  ^[3]

• Search DOE PAGES for author "Sessler, Jonathan L."
• Search DOE PAGES for ORCID "0000-0002-9576-1325"

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+ Show Author Affiliations

1. Univ. of Texas, Austin, TX (United States)
2. Univ. of Texas, Austin, TX (United States); Jiangsu Univ., Zhenjiang (China)
3. Univ. of Texas, Austin, TX (United States); Shanghai Univ. (China)

Publication Date:

Tue Jun 11 00:00:00 EDT 2019

Research Org.:

Univ. of Texas, Austin, TX (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); Robert A. Welch Foundation

OSTI Identifier:

1598886

Grant/Contract Number:  

FG02-01ER15186; 56925-ND7; F-0018

Resource Type:

Accepted Manuscript

Journal Name:

Accounts of Chemical Research

Additional Journal Information:

Journal Volume: 52; Journal Issue: 7; Journal ID: ISSN 0001-4842

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Anions; Hydrogels; Materials; Receptors; Polymers