Complex formation of pyridine‐azacrown ether amide macrocycles with proton and heavy metal ions in aqueous solution

Abstract

This research concerns the analysis of the proton and metal ion binding of amide macrocycles of different structures and sizes by potentiometric, 1 H NMR and X-ray diffraction methods. Protonated ligands exist as a 3D network structures.

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

“…Moreover all considered ligands are functionalized with picolinate arms thus allowing to reveal the influence of a pendant arm compared to earlier reported acetate and arm-free pyridine azacrowns. [13,23]…”

Synthetic Approaches to the Bifunctional Chelators for Radio­nuclides Based On Pyridine-Containing Azacrown Compounds

“…[26][27][28] In our earlier studies, the synthesis of the new derivatives of pyridine containing azacrown compounds and their complex formation with heavy metal ions have been reported. 29,30 The rigid structure of pyridine-2,6-dicarboxamide fragment provides fast kinetics of complex formation, the introduction of additional coordination groups improves the binding properties of macrocycles. These chelators have also been tested as chelating agent for radionuclides.…”

“…Synthetic methodology for building the skeletal backbone of pyridine-azacrown compound is the double amidation reaction 29,[52][53][54] with high efficiency in the crucial macrocyclization step. Herein, we wish to demonstrate that this approach provides an easy access to new BFCs.…”

“…It should be noted that the presence of additional ester groups in the 4-position of the pyridine ring did not have a noticeable negative effect on the process of macrocyclization if the yields of 2a,b are compared with those of analogous unsubstituted pyridine containing azamacrocyclic compounds described earlier. 29 We propose that the pyridine nitrogen atom affects the formation of the macrocycle due to the formation of hydrogen bonds with polyamine. In any case, this does not exclude the possibility of side reactions occurring in the ester group located in the 4-position of the pyridine ring.…”

“…Compound 2a was prepared according to a modified procedure. 29 A solution of triethylenetetramine (289 mg, 1.97 mmol) in MeOH (50 mL) was quickly added to a solution of triester 1 (500 mg, 1.97 mmol) in MeOH (100 mL) at RT. The mixture was stirred for 7 days and then the solvent was evaporated in vacuum.…”