Synthesis and Stereochemistry of Highly Unsymmetric β,Meso-Linked Porphyrin Arrays

Porphyrin arrays with tailor-made photophysical properties and well-defined three-dimensional geometries constitute attractive synthetic targets in porphyrin chemistry. The paper describes a variable, straightforward synthetic procedure for the construction of β,meso-linked porphyrin multichromophores in good to excellent yields. In a Suzuki-type coupling reaction β-borylated 5,10,15,20-tetraarylporphyrins (TAPs) served as versatile building blocks for the preparation of a plethora of directly linked, unsymmetrically substituted di- and triporphyrins. Besides their interesting photophysical properties, especially the trimeric porphyrin arrays show exciting stereochemical features. The established protocols thus open a convenient entry into the synthesis of achiral and chiral, unsymmetrically substituted β,meso-linked oligoporphyrins, e.g., for applications in biomedicine or nonlinear optics.