Organic nanostructures with controllable morphology fabricated from ferrocene–porphyrin derivatives: Effect of metal-ligand coordination on the morphology, dimension and nonlinear optical properties

A new ferrocene–porphyrin derivative, namely 5,15-bisferrocenyl-porphyrinato zinc was designed and synthesized. Its self-assembly behavior in the absence and presence of 4,4′-bipyridine had been comparatively investigated. Depending on the intermolecular π–π interaction, the ferrocene–porphyrin self-assembled into lotus flower-like nanostructures in the absence of 4,4′-bipyridine. However, when the equivalent of 4,4′-bipyridine was added into the self-assembly solution of the ferrocene–porphyrin, nanobelts were obtained depending mainly on the Zn–N4,4′-bipyridine coordination bonds between the zinc atom of the ferrocene–porphyrin and the nitrogen atom of the additional 4,4′-bipyridine. Further investigation about the nonlinear optical properties of both aggregates revealed that the nanostructures fabricated from the ferrocene–porphyrin exhibited saturation absorption in the absence of 4,4′-bipyridine and reverse saturation absorption in the presence of 4,4′-bipyridine.