Tuning photoinduced energy- And electron-transfer events in subphthalocyanine-phthalocyanine dyads

David González-Rodríguez, Christian G. Claessens, Tomas Torres, Shenggao Liu, Luis Echegoyen, Nuria Vila, Santi Nonell

Producció científica: Article en revista indexadaArticleAvaluat per experts

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Resum

A series of subphthalocyanine-phthalocyanine dyads has been prepared by means of palladium-catalyzed cross-coupling reactions between a monoalkynylphthalocyanine and different monoiodosubphthalocyanines. Electronic coupling between the two photoactive units is ensured by a rigid and π-conjugated alkynyl spacer. In addition, the electronic characteristics of the subphthalocyanine moiety were modulated by the introduction of different peripheral substituents. Cyclic and Osteryoung square-wave voltammetry experiments revealed that the reduction potential of this subunit can be decreased by about 400 mV on going from thioether or no substituants to nitro groups. As a consequence, the energy level of the charge-transfer state could be fine-tuned so as to gain control over the fate of the photoexcitation energy in each subunit. The diverse steady-state and time-resolved photophysical techniques employed demonstrated that, when the chargetransfer state lies high in energy, a quantitative singlet-singlet energy-transfer mechanism from the excited subphthalocyanine to the phthalocyanine takes place. On the contrary, stabilization of the radical pair by lowering the redox gap between electron donor and acceptor results in a highly efficient photoinduced electron-transfer process, even in solvents of low polarity such as toluene (ΦET ≈ 0.9). These features, together with the extraordinary absorptive cross section that these molecular ensembles display across the whole UV/Vis spectrum, make them model candidates for application in situations where broadband light sources are needed.

Idioma originalAnglès
Pàgines (de-a)3881-3893
Nombre de pàgines13
RevistaChemistry - A European Journal
Volum11
Número13
DOIs
Estat de la publicacióPublicada - 20 de juny 2005

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