LAUSR

Abstract A modified Pictet-Spengler protocol has been applied to synthesize novel π-extended copper(II) pyrrolo[1,2-a]pyrazinoporphyrins in good yields at 25 °C by using p-dodecylbenzenesulfonic acid as Bronsted acid catalyst. On demetallation in the presence of concentrated sulfuric acid, these copper porphyrins afford the corresponding free-base tetrapyrrolic systems which react with zinc acetate to generate zinc(II) pyrrolo[1,2-a]pyrazinoporphyrins in excellent yields. The structures of newly synthesized porphyrins were confirmed on the basis of spectral data. Furthermore, these porphyrins have been evaluated for their electronic properties and mercuric ion recognition by using electronic absorption and fluorescence spectroscopy. The photophysical results revealed a significant red shift in the Soret and Q bands of these porphyrin macrocycles due to the extended π-conjugation. Among the synthesized pyrrolo[1,2-a]pyrazinoporphyrins, the free-base porphyrins have demonstrated an excellent and selective sensing ability towards the mercuric ions in acetonitrile at ambient temperature.