Construction of light-harvesting materials

ImidazolylporphyrinatoZn gave a complementary coordination dimer of extraordinary stability. It exhibited excellent properties as a mimic of the structure and the function of the special pair of the reaction center in photosynthetic bacteria. Coupling of imidazolylporphyrinatoZn at the meso position afforded an array of a few hundreds nanometer to a micrometer scale. The linear array could be regarded as a unit of energy/electron transfer since no fluorescence quenching was observed by the array formation. When imidazolylporphyrinatoZn's were linked by a meta-phenylene grouping, macrocyclic porphyrin rings composed of 10 and 12 porphyrin units were obtained to represent the the light harvesting complex B 850 of photosynthetic bacteria. The linear array was attached on gold surface by thiolate extended from porphyrin. The assembled porphyrins have demonstrated significant improvement of the efficiency of photocurrent generation.