Large third-order optical nonlinearity of self-assembled porphyrin oligomers

Third-order nonlinear optical properties of two series of self-assembled porphyrin wires, one being terminated by zinc porphyrin and the other by free base porphyrin, were measured by femtosecond time-resolved optical Kerr effect. The hyperpolarizability values of the latter series were extremely large ranging from 10-30 to 10-29 esu, 10 times larger than the former. The behavior is accounted for by the contribution of terminal free base porphyrin to enhance the molecular polarization by acceptor nature toward central metalloporphyrin array. Copyright © 2002 American Chemical Society.