New Terpyridine-Containing Macrocycle for the Assembly of Dimeric Zn(II) and Cu(II) Complexes Coupled by Bridging Hydroxide Anions and π-Stacking Interactions
| Autor: | Barbara Valtancoli, Carlos Lodeiro, Fernando Pina, Emanuela Berni, Claudia Giorgi, Antonio Bianchi, Andrea Bencini, M. Alexandra Bernardo, Andrea Danesi, Carla Bazzicalupi, João C. Lima |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Inorganic Chemistry. 43:5134-5146 |
| ISSN: | 1520-510X 0020-1669 |
| DOI: | 10.1021/ic049660l |
| Popis: | The synthesis of the new terpyridine-containing macrocycle 2,5,8,11,14-pentaaza[15](6,6' ')cyclo(2,2':6',2' ')terpyridinophane (L) is reported. The ligand contains a pentaamine chain linking the 6,6' ' positions of a terpyridine unit. A potentiometric, (1)H NMR, UV-vis spectrophotometric and fluorescence emission study on the acid-base properties of L in aqueous solutions shows that the first four protonation steps occur on the polyamine chain, whereas the terpyridine nitrogens are involved in proton binding only at strongly acidic pH values. L can form both mono- and dinuclear Cu(II), Zn(II), Cd(II), and Pb(II) complexes in aqueous solution. The crystal structures of the Zn(II) and Cd(II) complexes ([ZnLH](2)(micro-OH))(ClO(4))(5) (6) and ([CdLH](2)(micro-Br))(ClO(4))(5).4H(2)O (7) show that two mononuclear [MLH](3+) units are coupled by a bridging anion (OH(-) in 6 and Br(-) in 7) and pi-stacking interactions between the terpyridine moieties. A potentiometric and spectrophotometric study shows that in the case of Cu(II) and Zn(II) the dimeric assemblies are also formed in aqueous solution containing the ligand and the metals in a 1:1 molar ratio. Protonation of the complexes or the addition of a second metal ion leads to the disruption of the dimers due to the increased electrostatic repulsions between the two monomeric units. |
| Databáze: | OpenAIRE |
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