Construction and photophysical properties of self-assembled linear porphyrin arrays

A novel linear multi-porphyrin array consisting of meso–meso coupled bis(imidazolyl-zinc-porphyrin) was constructed by complementary coordination of imidazolyl to zinc. Although the giant polymer forms in nonpolar solvents, the molecular weight was controlled simply by adding appropriate amount of coordinating solvents or chain terminators. Oligomeric porphyrin arrays terminated with free base porphyrin exhibited 10 times larger third-order optical response than those terminated by zinc porphyrin. Extremely large two-photon absorption cross-section values were obtained by using bis(imidazolyl-zinc-porphyrin) linked through acetylenic bonds as the array-forming units.