Construction of Hg^II complexes containing chelating 2,2′-dipyridylamine ligands: Anion effect, photoluminescence and catalytic activities

Five new structures of Hg^II complexes containing Hdpa ligands have been determined. With halides, tetrahedral Hg^II is constructed by a Hdpa and two chlorides or bromides, and strong hydrogen bonds between amine hydrogen atoms and halide atoms provide dimeric compounds. With benzoates, distorted octahedral Hg^II is constructed by a Hdpa and two chelating benzoate ligands, and hydrogen bonding and π-π interactions provide a polymeric compound. With nitrates or perchlorates, two dpa ligands bridge two HgII ions, and counter-anions axially coordinate to Hg^II ions to form a polymeric compounds. In addition, all five Hg^II complexes showed the intense emissions at room temperature, which are red-shifted compared to the corresponding ligand. Moreover, 3 and 4 have shown efficient catalytic transesterification recation, while 1, 2 and 5 has displayed a very slow conversion.