Interplay between H- bonding and interpenetration in an aqueous copper( II)- aminoalcoholpyromellitic acid system: self- assembly synthesis, structural features and catalysis

Two new copper(ii) coordination compounds, [Cu(H(1.5)mdea)(2)](2)(H(2)pma) (1a) and [{Cu-2(-Hmdea)(2)}(2)((4)-pma)](n)2nH(2)O (1b), were self-assembled at different temperatures from the same multicomponent reaction system, comprising copper(ii) nitrate, N-methyldiethanolamine (H(2)mdea), pyromellitic acid (H(4)pma), and potassium hydroxide. Products 1a and 1b were isolated as microcrystalline solids and fully characterized and their structures were established by single-crystal X-ray diffraction. Compound 1a features the bis-aminoalcohol(ate) monocopper(ii) units and H(2)pma(2-) anions that are multiply interconnected by strong H-bonds into a firm 2D H-bonded layer. Compound 1b reveals the bis-aminoalcoholate dicopper(ii) motifs that are interlinked by the (4)-pma(4-) spacers into a 3D + 3D interpenetrated metal-organic framework. From a topological perspective, both networks of 1a and 1b are uninodal and driven by similar 4-connected H(2)pma(2-) or pma(4-) nodes, but result in distinct sql and dia topologies, respectively. Compound 1a was applied as an efficient catalyst for two model cycloalkane functionalization reactions: (1) oxidation by H2O2 to form cyclic alcohols and ketones and (2) hydrocarboxylation by CO/H2O and S2O82- to form cycloalkanecarboxylic acids. The substrate scope, effects of various reaction parameters, selectivity and mechanistic features were also investigated.