Various copper-containing MOF catalysts i e [Cu(2-pymo)(2)] [Cu(im)(2)) [Cu-3(BTC)(2)] and [Cu(BDC)] (2-pymo 2-hydroxypyrimidinolate im imidazolate BTC benzene tricarboxylate BDC benzene dicarboxylate) have shown to be highly active and fully regioselective for click" reactions (1 3-dipolar cycloaddition reactions) The activity of the best MOF catalyst is comparable to homogeneous Cu catalysts It has been found that the activity of Cu changes with the organic linker in the MOF being those containing CuN4 more active than CuO4 centers The controlling step of the reaction is the formation of an adduct between Cu and phenylacetylene When using MOF catalysts the use of alcohol or alcohol-water solvents is not required and the catalysts can be fully recovered and recycled Finally Cu-MOF catalysts allow to design a one-pot two-step process where the azide is formed in situ and reacted immediately with phenylacetylene (C) 2010 Elsevier Inc All rights reserved