Azacoronands and Azacyclophanes

Abstract

Azacycloalkanes and azacyclophanes are among the first macrocyclic ligands developed in the field of supramolecular chemistry. Since they are polyamines, they show dual nature in the coordination of both metal cations, when they are in the free‐base form, and anionic species, when they are protonated. As a matter of fact, they played a key role in the birth of macrocyclic chemistry of transition metal complexes and anion coordination chemistry. Furthermore, azacyclophanes fostered also the birth of apolar complexation in aqueous solution, since their aromatic units act as binding sites for apolar substrates.

Spectroscopic, Structural, and Theoretical Studies of Halide Complexes with a Urea-Based Tripodal Receptor

“…Yield: 1.07 g, 90%. 1 H NMR (500 MHz, DMSO-d 6 , TSP): δ 9.14 (s, 3H, Ar-NH), 7.67 (d, J = 8.5 Hz, 6H, ArH), 7.58 (d, J = 8.5 Hz, 6H, ArH), δ 6.39 (m, J 1 = 5.5 Hz, J 2 = 5.05 Hz, 3H, CH  NH), 3.24 (m, J 1 = 6.1 Hz, J 2 = 5.95 Hz, J 3 = 5.90 Hz, 6H, NHCH 2 ), 2.64 (t, J 1 = 6.55 Hz, J 2 = 6.45 Hz, 6H, NCH 2 ). 13 [HL](Cl), 1.…”

“…Anions are ubiquitous in nature and play a key role in chemistry and biology. 1 Therefore, anion recognition with synthetic receptors remains an active area of research in supramolecular chemistry. 2,3 Early research in this area has focused primarily on polyamine-based receptors that require protonation to bind an anion.…”

Stabilization of Supramolecular Networks of Polyiodides with Protonated Small Tetra-azacyclophanes

“…Azacyclophanes have long been in the spotlight as pH-dependent anion receptors [20]. Moreover, some interesting results concerning the ability of these ligands to stabilize polyiodides, including the elusive I 4 2− anion, when in their protonated form [21], prompted us to investigate further concerning their binding possibilities.…”

Evaluation of the binding ability of a macrobicyclic receptor for anions by potentiometry and molecular dynamics simulations in solution

“…For instance, certain anions and pesticides or herbicides are known to cause water eutrophication and ground degradation. 1 In spite of the negative features, anions are fundamental compounds in pharmaceutical, food and plastic industries, and for the function and regulation of many biological processes, consequently they are essential to life. Supramolecular chemistry strongly contributed, and continues to contribute, to such new tools with the design of receptors, the investigation of their recognition ability and the selection of those capable to sense and uptake anionic substrates.…”