Twists and Loops: Exploring Lemniscular Vinylogous Benzioctaphyrin(2.0.1.0.2.0.1.0).

Abstract

Octaphyrins, offer unparalleled opportunities for designing complex molecular architectures with distinct physical and chemical properties. However, lemniscate-shaped benzioctaphyrins remain scantily explored, leaving a gap in understanding how this unconventional geometry/shape influences macrocyclic behaviour. In this study, we explore the design, synthesis, and structural properties of benzioctaphyrin by incorporating the bis-E-stilbene unit, where a vinylene π-bridge connects phenylene rings. The benzioctaphyrin(2.0.1.0.2.0.1.0) adopts a lemniscate topology to alleviate steric strain, with protonation inducing conformational desymmetrization. The presence of a meta-phenylene unit thwarts the global π-conjugation, rendering the macrocycle nonaromatic. Notably, this work represents the first exploration of the oligomeric vinylene group in benzioctaphyrin framework. It offers new insights into how structural modifications influence topology, π-electron delocalization, and macrocyclic flexibility, setting the stage for future advancements in topologically unique porphyrinoid systems.