Artificial light-harvesting antenna systems

The above studies provide evidence for the donor-to-donor energy migration within the assemblies of the chromophores built from a variety of systems, but they all share a common matrix for assembly. Such systems may be of interest in the construction of artificial light-harvesting antennas [67,72],... 

The p>orphyiins have attracted considerable attention because are ubiquitous in natural systems and have prosp>ective applications in mimicking enzymes, catalytic reactions, photodynamic therapy, molecular electronic devices and conversion of solar energy. In particular, munerous p>orphyrins based artificial light-harvesting antennae, and donor acceptor dyads and triads have been prepared and tested to improve our understanding of the photochemical aspect of natural photosynthesis. 

In our laboratory we are currently investigating several types of supramolecular systems which can play a role of artificial light-harvesting antennae or charge-separation devices. 

A synthetic system capable to perform artificial photosynthesis should contain the following basic components (i) light-harvesting antennae (ii) charge separation units (iii) light-activated multielectron transfer catalysts (see Fig. 1). ... 

Generally speaking, an antenna for light harvesting is an organized multicomponent system in which several chro-mophoric molecular species absorb the incident light and channel the excitation energy to a common acceptor component. Artificial antenna systems based on porphyrin arrays [63], multichromophoric cyclodextrins [64], polynuclear metal complexes [65, 66], dendrimers [66-68], and polymers [69, 70] have been reported. In all these systems, the chromophoric units are connected by means of covalent... 

Loiseau F, Marzanni G, Quiei S, Indelli MT, Campagna S (2003) An artificial antenna complex containing four [Ru(bpy) ]2+-type chromophores as light-harvesting component sand a [Ru (bpy)(CN)" ]2- subunit as the energy trap. A structural motif which resembles the natural photosynthetic systems. Chem Commun 286-287... 

Artificial antenna complexes that resemble biological counterparts in organization and light harvesting were published. These systems mimic the circular arrangement of pigments in the LH-II complex of purple bacteria. One such example is shown in Figure 9 12 porphyrins are noncovalently assembled to form a circular array, where the maximum separation, namely, radius of antenna, is 4.1 nm. ... 

To approach an artificial model from the chemical point of view, there is a need to simplify it in a basic donor-acceptor system, formed by one electron donor unit (D) and one electron acceptor unit (A), linked together throngh covalent or noncovalent interactions (Figure 2.23). This simple system (also called dyad) should efficiently give a long-lived CSS after irradiation with light. Donors supply a double function they not only act as excitation-harvesting antennas but also as primary electron donors that transfer electrons to the acceptor. 

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