Coordination polymers of 5-(2-amino/acetamido-4-carboxyphenoxy)-benzene-1, 3-dioic acids with transition metal ions: Synthesis, structure, and catalytic activity

As part of our extensive investigations of hybrid organic-inorganic coordination frameworks, we report herein on the construction and characterization of new polymeric assemblies obtained by reacting the title tricarboxylic ligand with various transition metal ions. While polymeric structures of binary metal-ligand composition and three-dimensional connectivity scheme could be obtained with the f-shell lanthanoid ions, formulation of crystalline supramolecular assemblies with d-shell transition metals required incorporation of a third bipyridyl component in the reaction mixture. The latter present materials of ternary metal-ligand-bipyridyl content and layered structures composed of two-dimensional coordination polymers. The detailed coordination patterns of varying geometric features have been revealed by single-crystal X-ray diffraction. It has been also shown that selected polymeric solids act as heterogeneous catalysts in acetylation reactions of alcohols. The two-dimensional polymeric assemblies with nickel show higher catalytic reactivity than the three-dimensional framework solids of lanthanum, as in the former coordination networks the access of the reactant species to the metal centers and the Lewis base N-sites is less hindered.