Macrocyclic polyether tetralactams II : a study of their binding properties with alkaline - earth cations

New Trends in the Chemistry of Condensed Heteromacrocycles. Part A. Condensed Azacrown Ethers and Azathiacrown Ethers

“…In this part we focus on macrocyclic polyether di-and tetralactams not only for being valuable intermediates for the synthesis of azacrowns and related compounds but also for their wide applications in selective noble metal complexing [54,55] and as metal ion selective electrodes [56]. For example, incorporation of an amide linkage in a polyether macrocycle has been found to modify the binding properties of crown ether compounds to favor alkaline earth cations over alkali metal cations [57][58][59].…”

A convenient synthesis of thiamacrocyclic dilactams

“…It has also been reported that the type of macrocyclic heteroatoms, number of amide groups, ring size, lipophilic groups as well as other structural features control their selectivity toward different ions [11][12][13][14][15][16]. For example, to improve the binding ability of macrocyclic receptors for alkali metal cations, such attention has been paid to the development of functional groups in the ring [17][18][19] as incorporation of an amidic linkage in a polyether macrocycle may modify the binding properties of crown ether compounds to favor the alkali earth cations over alkali metal cations [20][21][22][23][24]. Gokel and coworkers have found that diaza-18-crown-6 derivatives with amide groups in their side chains exhibit extraordinary Ca 2+ binding strength and remarkable selectivity for Ca 2+ over Na + [25], although a number of synthetic cyclopeptides are K + or Ca 2+ ionophores [26].…”

Synthesis of mixed‐donor azaoxathia macrocyclic tetraamides, acyclic polyether di/and tetraamides and their C‐pivot lariat derivatives

“…For this reason, many different modifications have been made to the basic crown ether structures in an attempt to enhance the selectivity of these ligands and the stability of complexes formed with a wide variety of metal ions. These modifications involved substitution of ligand polyether oxygen donor atoms by sulfur and/or nitrogen atoms [3,4]. Macrocycles containing nitrogen and/or sulfur donor atoms are of interest as they exhibit high affinities towards heavy transition metal ions and their selectivity is readily tunable by altering the composition of the donor-atom set and ring size [5,6].…”

“…It has also been reported that macrocyclic ligands with amide functional groups as binding sites form strong and selective complexes with noble [15][16][17] and transition [18] metals. Moreover, macrocyclic tetraamides are of increasing interest in several fields such as valuable synthetic intermediates of azacrown [19], azaparacyclophanes [20] or macropolycyclic polyethers (cages) [21], artificial receptors of biological substrate [22], enzyme model [23] or synthetic enzymes (synzymes) [24], neutral ionophores for selective alkalineearth ions extraction [25], transport through a bulk membrane [26] or ion-selective electrode incorporated membrane [27], luminescent lanthanide probes [28], ligands for highly oxidizing transition metal complexes [29], linkers for distribution of donor chelating sites in binuclear complexes [30] and interlocking moieties in neutral catenanes [31]. Further modification involved the attachment of a flexible side arm, with extra potential metal ion coordination sites, to a crown-ether framework producing complexing agents known as lariat crown ethers [32].…”