Spectroscopy and Coordination Chemistry of a New Bisnaphthalene-Bisphenanthroline Ligand Displaying a Sensing Ability for Metal Cations
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- 作者：Joã ; o Pina ; J. Seixas de Melo ; Fernando Pina ; Carlos Lodeiro ; J. C. Lima ; A. Jorge Parola ; Conxa Soriano ; M. Paz Clares ; M. Teresa Albelda ; Ricardo Aucejo ; and Enrique Garcí ; a-Españ
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：October 17, 2005
- 年：2005
- 卷：44
- 期：21
- 页码：7449 - 7458
- 全文大小：343K
- 年卷期：v.44,no.21(October 17, 2005)
- ISSN：1520-510X
文摘
A new fluorescent macrocyclic structure (L1) bearing two naphthalene units at both ends of a cyclic polyaminicchain containing two phenanthroline units was investigated with potentiometric and fluorescence (steady-state andtime-resolved) techniques. The fluorescence emission spectra show the simultaneous presence of three bands: ashort wavelength emission band (naphthalene monomer), a middle emission band (phenanthroline emission), anda long-wavelength band. All three bands were found to be dependent on the protonation state of the macrocyclicunit (including the polyaminic and phenanthroline structures). The existence of the long-wavelength emission bandis discussed and is shown to imply that a bending movement involving the two phenanthroline units leads toexcimer formation. This is determined by comparison with the excimer emission formed by intermolecular associationof 1,10-phenanthroline. With ligand L1, excimer formation occurs only at pH values above 4. At very acidic pHvalues, the protonation of the polyamine bridges is extensive leading to a rigidity of the system that precludes thebending movement. The interaction with metal cations Zn(II) and Cu(II) was also investigated. Excimer formationis, in these situations, increased with Zn(II) and decreased with Cu(II). The long-emission band is shown to presenta different wavelength maximum, depending on the metal, which can be considered as a characteristic to validatethe use of ligand L1 as a sensor for a given metal.