Third-order nonlinear optical properties of highly electron deficient, nonplanar push–pull porphyrins: β-nitro-hexa-substituted porphyrins bearing bromo, phenyl, and phenylethynyl groups

β-Heptasubstituted porphyrins were synthesized and their third-order nonlinear optical (NLO) properties were explored. The existence of enhanced polarization and intramolecular charge transfer are held responsible for the observed strong NLO responses.