(Invited) Synthesis and Structures of Free-Base [14]Tribenzotriphyrin(2.1.1) and Their Metal Complexes

Abstract

Subporphyrins are analogues of porphyrinoids that contain only three pyrrole or isoindole rings linked by meso-sp2 carbon atoms. The first synthesis of tribenzosubporphyrins was reported by Osuka’s group in 2006 with very harsh conditions. From then on, lots of subporphyrin analogues have been reported. However, almost all of these reported subporphyrins existed only as bowl-shaped boron complexes and the yields are typically very low. In 2008, we reported a facile synthesis of meso-aryl-substituted [14]benzotriphyrin(2.1.1) compounds based on a modified Lindsey condensation method in moderate yields up to 35%. These compounds represent the first example of near planar core-free contracted porphyrinoids with 14-π-electron aromatic systems containing only the standard pyrrole and isoindoline moieties. X-ray diffraction analysis revealed that the triphyrin core is near planar. Till now, different kinds of [14]Tribenzoriphyrin(2.1.1)-metal complexes have been synthesized and characterized including Ag(I), Mn(I), Fe(II), Re(I), Ru(II), Pd(II), Rh(III), Pt(II) and Pt(IV).