Copper(II) complexes of chiral 1, 2, 3-triazole biheterocyclic 'click' ligands equipped in Cinchona alkaloid moiety. (10th January 2017) - Gałęzowska, J.
Graphical abstract: Efficient synthetic procedure to obtain chiral 1, 2, 3-triazole click conjugated Cinchona alkaloid compounds using CuAAC reaction is shown, together with coordination studies of those multifunctional ligands towards Cu(II). Several methods (potentiometry, UV–Vis spectroscopy, mass spectrometry and calorimetry) were employed to estimate the presence of complexes with studied ligands in the solution; their stabilities, stoichiometry, thermodynamic behavior and coordination mode and to answer the question if the Cinchona moiety will be left unbound and available for other potential activities. Abstract: Chiral 1, 4-disubstituted-1, 2, 3-triazole mono- and biheterocyclic 'click' ligands derived from Cinchona alkaloids were synthesized using copper(I) catalyzed azide–alkyne cycloaddition (CuAAC) and studied in terms of coordination chemistry towards Cu(II). In broad range of pH the studied ligands form complexes with stoichiometry ML2 in which the coordination involves two neighboring nitrogen atoms from 1, 2, 3-triazole (N3) and pyridine unit, respectively. The copper(II) coordination is site-selective among studied ligands (L 1, 2, 4 ) apart forL 3, which due to the lack of pyridine next to the triazole moiety and/or possible steric strain in formed complex turned out to be the ligand which metal binding is weaker than others under studied conditions. Thermodynamic analysis which involved potentiometric and calorimetric studies revealed relatively low stability of formed complexes, which binding events are entropy driven processes.