Synthesis, circular dichroism, and third-order nonlinear optical properties of optically active porphyrin derivatives bearing four chiral citronellal moieties

(R)-Enantiomer of optically active metal free porphyrin, bearing four chiral citronellal units linked directly onto the meso positions of the porphyrin ring, and its zinc congener, namely (R)-meso-5,10,15,20-tetra-(2,6-dimethyl-5-heptenyl) porphyrin [(R)-H2T(C9H17)4P (1)] and (R)-meso-5,10,15,20-tetra-(2,6-dimethyl-5-heptenyl) porphyrinato zinc complex [(R)-ZnT(C9H17)4P (2)], have been designed and synthesized. These two compounds were characterized by a wide range of spectroscopic methods. In contrast to the CD silent of a similar compound N,N′,N″-Tris{21H,23H-5-p-Aminophenyl-10,15,20-tris-[p-(S)-3,7-dimethyloctoxyphenyl]porphyrin}-1,3,5-tricarboxamid, bearing the similar chiral units linked onto the meso positions of the porphyrin ring via meso-attached benzene, observation of a positive CD signal in the Soret absorption region of both porphyrin compounds, not only indicate effectively chiral information transfer from the chiral citronellal tails to porphyrin chromophore at the molecular level, but also reveal the effect of substituents position on the asymmetrical perturbation. In addition, both compounds were revealed to show good third-order nonlinear optical properties.

► Optically active metal free porphyrin and its zinc congener were synthesized.
► Both compounds show positive CD signals in the Soret absorption region.
► This indicates the effect of substituents position on the asymmetrical perturbation.
► In addition, both compounds show good third-order nonlinear optical properties.