Triazole Derivative Ligands for Coordination Chemistry

In coordination chemistry, architectures containing the triazole heterocycle have been developed as monodentate and polydentate nitrogen ligands. Special attention has been given to (2-pyridyl)- and more flexible (2-picolyl)-l,2,3-triazoles. Thus, a hbrary of selected 1,4-disubstituted 1,2,3-triazoles differently functionahzed with pyridine, pyrimidine, and pyrazine have been synthesized by the reaction of aryl, heteroaryl, and heteroarylmethyl azides with alkynes. Three different copper(l) sources, that is, CuSO /sodium ascorbate, CuBrlPPhglg, and (CuOTf)2 CgHg, were used to promote the reactions [89]. 

The copper-catalyzed azide-alkyne cycloaddition is particularly suitable for F-labehng of sensitive biomolecules. Three different radiolabeled alkyne precursors react with azido-functionalized peptides in radiochemical yields (RCYs) of 54-99% and an overall reaction time of 30 min. The reaction is catalyzed by copper sulfate in combination with ascorbic acid or sodium ascorbate. Addition of bathophenanthroline disulfonate (Cul stabilizing agent) accelerates the cycloaddition [90]. 

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