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EnglishComplexation of Zn(II) ions by cyclam cored dendrimers appended with four (G0), eight (G1) and 16 naphthyl chromophores (G2) at the periphery have been investigated in CH3CN-CH2Cl2 1 : 1 (v/v) solution by absorption and emission, ESI-mass and H-1 NMR spectroscopy. The results obtained can be interpreted by the formation of complexes of 2 : 1 dendrimer to metal stoichiometry, at low metal ion concentration, and 1 : 1 complexes upon further addition of Zn(II) ions, for all the dendrimer generations. Upon addition of a molecular clip C2- consisting of two anthracene sidewalls bridged by a benzene group with two sulfate substituents in the para positions, heteroleptic complexes of general formula [GnZnC] are formed. Interestingly, in these complexes, a very efficient quenching (practically 100%) of the dendrimer naphthyl luminescence and sensitization (ca. 90%) of the clip anthracene emission take place. The complex [G2ZnC] exhibits a very high molar absorption coefficient in the UV spectral region owing to the 16 naphthyl chromophores of the dendrimer and the two anthracene units of the clip (epsilon = 1.7 x 10(5) M-1 cm(-1) at 263 nm). Furthermore, the excitation energy absorbed by the naphthyl chromophores is efficiently funneled to the two anthracene units of the clip, which emits in the blue spectral region.
| Titolo: | A molecular clip throws new light on the complexes formed by a family of cyclam cored dendrimers with Zn(II) ions. Efficient energy transfer in the heteroleptic complexes. |
| Autore/i: | BRANCHI, BARBARA; BERGAMINI, GIACOMO; L. Fiandro; CERONI, PAOLA; A. Alvino; G. Doddi; F. Vögtle; F. G. Klärner |
| Autore/i Unibo: | |
| Anno: | 2011 |
| Rivista: | |
| Digital Object Identifier (DOI): | http://dx.doi.org/10.1039/c0dt01202e |
| Abstract: | Complexation of Zn(II) ions by cyclam cored dendrimers appended with four (G0), eight (G1) and 16 naphthyl chromophores (G2) at the periphery have been investigated in CH3CN-CH2Cl2 1 : 1 (v/v) solution by absorption and emission, ESI-mass and H-1 NMR spectroscopy. The results obtained can be interpreted by the formation of complexes of 2 : 1 dendrimer to metal stoichiometry, at low metal ion concentration, and 1 : 1 complexes upon further addition of Zn(II) ions, for all the dendrimer generations. Upon addition of a molecular clip C2- consisting of two anthracene sidewalls bridged by a benzene group with two sulfate substituents in the para positions, heteroleptic complexes of general formula [GnZnC] are formed. Interestingly, in these complexes, a very efficient quenching (practically 100%) of the dendrimer naphthyl luminescence and sensitization (ca. 90%) of the clip anthracene emission take place. The complex [G2ZnC] exhibits a very high molar absorption coefficient in the UV spectral region owing to the 16 naphthyl chromophores of the dendrimer and the two anthracene units of the clip (epsilon = 1.7 x 10(5) M-1 cm(-1) at 263 nm). Furthermore, the excitation energy absorbed by the naphthyl chromophores is efficiently funneled to the two anthracene units of the clip, which emits in the blue spectral region. |
| Data prodotto definitivo in UGOV: | 2013-06-17 15:09:55 |
| Appare nelle tipologie: | 1.01 Articolo in rivista |
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