Template-Directed Synthesis of Strained meso-meso-Linked Porphyrin Nanorings

Angew Chem Int Ed Engl. 2024 Apr 2;63(14):e202400103. doi: 10.1002/anie.202400103. Epub 2024 Mar 1.

Abstract

Strained macrocycles display interesting properties, such as conformational rigidity, often resulting in enhanced π-conjugation or enhanced affinity for non-covalent guest binding, yet they can be difficult to synthesize. Here we use computational modeling to design a template to direct the formation of an 18-porphyrin nanoring with direct meso-meso bonds between the porphyrin units. Coupling of a linear 18-porphyrin oligomer in the presence of this template gives the target nanoring, together with an unexpected 36-porphyrin ring by-product. Scanning tunneling microscopy (STM) revealed the elliptical conformations and flexibility of these nanorings on a Au(111) surface.

Keywords: nanorings; oligomers; porphyrinoids; scanning probe microscopy; templates.