Ion and Molecular Recognition Using Aryl–Ethynyl Scaffolding

Abstract

The aryl–ethynyl linkage has been extensively employed in the construction of hosts for a variety of guests. Uses range from ion detection (e.g., of metal cations in the environment or industrial waste and of anions prevalent in nature), to molecular mimics for biological systems, and to applications targeting future safety issues (such as CO2 capture and indicators for the manufacture of chemical weapons). This Focus Review examines the utilization of the aryl–ethynyl linkage in engineering host molecules for a variety of different guests, and how the alkyne unit plays an integral part as both a rigid scaffolding section in host geometry design as well as a linker to allow conjugative communication between discrete π-electron systems.

Substituent Effects in CH Hydrogen Bond Interactions: Linear Free Energy Relationships and Influence of Anions

“…30–36 In this case, pendent methoxy substituted phenylureas act as additional HB donors to direct the anion binding into a single site, as illustrated in Figure 2b. 19,32,35 The synthesis of 1a has been previously reported and forms the parent scaffold for our study of substituent effects.…”

“…27 These receptors are highly modular and easily broken into three key units for stepwise synthesis—a core arene, an alkynyl aniline, and an isocyanate. 36 For the current investigation, the core arene can be any 3,5-dibromo- or 3,5-diiodobenzene suitable for Sonogashira cross-coupling possessing either an electron-withdrawing or electron-donating substituent in the 1-position. The t -Bu group on the alkynyl aniline was used to provide solubility in noncompetitive organic solvents (i.e., CHCl 3 ).…”

Sulfoxide‐Induced Homochiral Folding of ortho‐Phenylene Ethynylenes (o‐OPEs) by Silver(I) Templating: Structure and Chiroptical Properties

“…Within this context, the study of oligomeric structures able to adopt well‐defined secondary conformations is a research field of growing interest. In particular, all‐conjugated aryl ethynyl oligomers have been extensively used as hosts of different species . For instance, meta ‐ and ortho ‐phenylene ethynylenes ( o ‐OPEs) are able to reversibly fold into helical arrangements, even in a chiral way if chiral side chains or chiral subunits exist in the backbone, or in the presence of chiral guests…”

Solid-State Examination of Conformationally Diverse Sulfonamide Receptors Based on Bis(2-anilinoethynyl)pyridine, -Bipyridine, and -Thiophene

“…14–17 This rigid and linear motif provides suitable geometric dimensions for both macrocyclic and acyclic receptors. Furthermore, alteration of the aryl moiety (e.g., inclusion of N-based heterocycles such as pyridine) has enabled applications in coordination chemistry, such as selective transition metal and small molecule complexation as well as fluorescence sensing.…”