SNAr Reaction Toward the Synthesis of Fluorinated Quinolino[2,3,4‐at]porphyrins

Abstract

AbstractAn intramolecular SNAr displacement of one o‐fluorine atom of a meso‐pentafluorophenyl‐substituted porphyrin metal complex by a neighboring β‐amino functionality generated the corresponding meso‐fluorophenyl‐substituted metallo‐quinolino[2,3,4‐at]porphyrins that are not accessible using established quinoline‐annulation methodologies. The Cu(II), Ni(II), and Zn(II) complexes were thus prepared. The parent free base quinolino[2,3,4‐at]porphyrin is accessible only by demetallation of the copper or zinc complexes. A strong through‐space NMR‐spectroscopic coupling between the remaining o‐fluorine atoms on the annulated meso‐aryl group and the β‐hydrogen atom on the adjacent pyrrole moiety provide a clear spectroscopic signature for the annulation. Quinoline‐annulation alters the optical properties significantly. On account of the presence of the β‐amino functionality, all quinoline‐annulated porphyrins show strong halochromic responses with Brønsted acids and bases, the prerequisite for their potential use in chemosensing applications.