Aromatic and heteroaromatic azacrown compounds: advantages and disadvantages of rigid macrocyclic ligands

Abstract

Current approaches to the synthesis of aromatic and heteroaromatic azamacrocycles and their derivatives are summarized and systematized. The relationship between the structure of azacrown compounds and their complexation behaviour towards metal cations is analyzed. The diversity of practical applications of azamacrocyclic derivatives in medicine, biology and analytical and organic chemistry, as well as for the design of molecular devices is demonstrated. The bibliography includes 307 references.

Comparative Study of Macrocyclic and Acyclic Picolinate Derivatives for Chelation of Copper Cations

“…Macrocyclic ligands possessing a certain degree of rigidity often demonstrate superior stability of formed complexes compared to acyclic analogues. [6][7][8] The cyclen, cyclam, sarcofagine and bispidine-based ligands have been shown to form stable chelates with Cu 2 + . [9][10][11][12] At present only sarcofagine and DOTAderivatives are under clinical trials for PET 64 Cu based radiopharmaceuticals.…”

Grafting of the 2,8-dithia-5-aza-2,6-pyridinophane macrocycle on SBA-15 mesoporous silica for the removal of Cu2+ and Cd2+ ions from aqueous solutions: synthesis, adsorption, and complex stability studies

“…Nevertheless, the practical application of the complexes is limited by slow complexation kinetics. 22 The stability of metal/aliphatic ligands complexes is strongly influenced by entropy. Free aliphatic macrocyclic ligands occur in solution as a mixture of several conformers in dynamic equilibrium.…”

“…[19][20][21] Among hundreds of known metal-chelating molecules, macrocyclic ligands are particularly interesting due to their ability to bind alkaline earth and transition ( particularly heavy) metals both in water and organic solvents by changing their molecular structure and the nature of donor atoms. [22][23][24] The ligand-metal binding property is mainly provided by the presence of electron-donor atoms with appropriate soft-hard properties, while the metal selectivity can be modulated by the macrocycle ring size and conformational properties. 22 Aromatic rings, often introduced into the macrocyclic structure to provide a structurally rigid moiety, are also important moieties for the coordination of metal ions especially within small-sized macrocyclic polyamine systems.…”

“…[22][23][24] The ligand-metal binding property is mainly provided by the presence of electron-donor atoms with appropriate soft-hard properties, while the metal selectivity can be modulated by the macrocycle ring size and conformational properties. 22 Aromatic rings, often introduced into the macrocyclic structure to provide a structurally rigid moiety, are also important moieties for the coordination of metal ions especially within small-sized macrocyclic polyamine systems. 25 For instance, Blake et al 26 studied extensively the coordination properties towards "borderline" and "soft" metal ions (e.g.…”

A general and stereoselective approach to 14-membered cyclic bis-semicarbazones involving BF3-catalyzed amidoalkylation of 2-(trimethylsilyloxy)propene

“…A unique feature of PAM is their ability to bind different inorganic and organic cations, anions, and neutral molecules. 1,2 PAM and their metal complexes exhibit a broad range of biological activities 3 including anticancer, 4 anti-HIV, 5 antibacterial and antifungal activities. 6 The metal complexes are also used as radiopharmaceuticals, 7 MRI contrast agents, 8 NMR shift reagents, 9 luminescent materials, 9 b ,10 sensors, 10 a ,11 catalysts, 12 etc .…”