Multichromophoric array

Figure 9 A schematic of the tobacco mosaic virus (TMV) light-harvesting assembly from an external and internal view. The internal view represents the orientation and helical nature of the multichromophoric array.

Whether EEM actually occurs within a particular multichromophoric array, and if so with what rate and efficiency, and by what mechanism, are important factors still to be determined if this process is to be fully understood and harnessed. Through this knowledge, and the design and synthesis of optimized macromolecular structures, EEM efficiency may be maximized for use in applications in photomolecular devices exploiting the photon-harvesting apparatus (Fox, 1993). 

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... 

The synthesis of ruthenium-metallated Pc derivatives using Ru3(CO)i2 in benzonitrile afforded ruthenium phthalocyanines either monocoordinated with CO or dicoordinated with benzonitrile. Cook and colleagues were the first to predict their utility in the preparation of further (pyridyl) ligated derivatives and showed that it was indeed straightforward. This chemistry is sufficiently robust and efficient to permit elaborate supramolecular complexes to be prepared, as demonstrated by the synthesis of porphyrin-phthalocyanine multichromophores 21 and 22, as illustrated in Figure 15. The absorption spectra of these arrays are essentially the sums of spectra of the starting materials. These observations indicate that there is little ground-state electronic interaction between the perpendicular maaocycles, in accordance with previous results published by Ng and Li (Section 4.1.1). ... 

A thorough study of POP-scaffold based zipper assemblies was reported recently. However, it is rather difficult to compare obtained results because of the missing quantitative information such as Voc, he, 9. and EQE values. Nevertheless, the performed studies clearly demonstrated a great potential for the design of multichromophore self-assembled light harvesting molecular arrays. 

Metal-mediated cross-coupling reactions involving mcw-haloporphyrins enable the fabrication of porphyrin arrays that exhibit exceptional electronic interactions between their constituent porphyrinic building blocks. Because mew-halopor-phyrins derive from direct halogenation of the porphyrinic aromatic macrocycle, porphyrins bearing unsubstituted meso positions are important synthetic precursors to these supramolecular, multichromophoric systems. 

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