NIR Absorbing Aromatic E-Ethylene Bridged Hexaphyrins (2.1.1.2.1.1): Synthesis, Characterization, and Protonation Studies

Abstract

Judicious syntheses, spectroscopic analyses, and solid state structural evidence of two structural variants (with planar geometry) of strongly aromatic hybrid [30] E-ethylene bridged hexaphyrins (2.1.1.2.1.1) exhibiting strong NIR absorption are reported. The induced correspondence of fused phenanthrene on the pyrrole moieties has led to a further red-shift of up to ∼45 nm in the neutral and protonated form of the macrocycles. The electronic nature and aromaticity of both hexaphyrins are fully supported by DFT calculations.

28π Non‐Fused Hexaphyrin: Synthesis, Protonation Triggered Möbius Aromaticity and Structural Properties

“…Furthermore, Rath et al. recently achieved the synthesis of E‐configured hexaphyrins 5 [34] . In our previous work, we demonstrated the synthesis of two different substituted vinyl‐bridged hexaphyrins, E‐[28]hexaphyrin(2.1.1.0.1.1) 6 and Z‐[30]hexaphyrin(2.1.1.2.1.1) 7 [15] .…”

“…[33] Furthermore, Rath et al recently achieved the synthesis of E-configured hexaphyrins 5. [34] In our previous work, we demonstrated the synthesis of two different substituted vinyl-bridged hexaphyrins, E-[28]hexaphyrin(2.1.1.0.1.1) 6 and Z- [30]hexaphyrin(2.1.1.2.1.1) 7. [15] In continuation of our effort, in the present work we are going to highlight the synthesis of a non-fused E-[28]hexaphyrin(2.1.1.0.1.1) 8 and protonation triggered transformation of non-aromatic to Möbius aromatic species.…”