Issue 6, 2011
From the journal:

Dalton Transactions

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†

Barbara Branchi,a   Giacomo Bergamini,a   Luca Fiandro,a   Paola Ceroni,*a   Antonello Alvino,b   Giancarlo Doddi,*c   Fritz Vögtled  and  Frank-Gerrit Klärnere  

* Corresponding authors

a Dipartimento di Chimica “G. Ciamician” and Centro Interuniversitario per la Conversione Chimica dell'Energia Solare, Università di Bologna, via Selmi 2, Bologna, Italy
E-mail: paola.ceroni@unibo.it
Fax: +39 051 2099456
Tel: +39 051 2099535

b Dipartimento di Chimica, Università di Roma La Sapienza, P.le Aldo Moro 5, Rome, Italy

c Dipartimento di Chimica e CNR-IMC, Università di Roma La Sapienza, P.le Aldo Moro 5, Rome, Italy
E-mail: giancarlo.doddi@uniroma1.it
Fax: +39 06 490631
Tel: +39 06 49913077

d Kekulé-Institut für Organische Chemie und Biochemie der Universität Bonn, Gerhard-Domagk Strasse 1, Bonn, Germany

e Institut für Organische Chemie der Universität Duisburg-Essen, Campus Essen, Universitätsstr. 5, Essen, Germany

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 1H 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 [GnnZnC] 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 (ε = 1.7 × 105 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.

Graphical abstract: 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

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Article information

DOI
https://doi.org/10.1039/C0DT01202E
Article type
Paper
Submitted
10 Sep 2010
Accepted
16 Nov 2010
First published
22 Dec 2010

Dalton Trans., 2011,40, 1356-1364

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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

B. Branchi, G. Bergamini, L. Fiandro, P. Ceroni, A. Alvino, G. Doddi, F. Vögtle and F. Klärner, Dalton Trans., 2011, 40, 1356 DOI: 10.1039/C0DT01202E

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