NIR absorbing aromatic (antiaromatic) vinylogous carbasapphyrins (3.3.1.0.1) with built-in fused dipolar aromatic hydrocarbon: synthesis and characterization

Expedient syntheses, spectroscopic, solid state structural proof and theoretical study of three structural variants (with planar geometry) of strongly aromatic (antiaromatic) hybrid [26]/[24] vinylogous carbasapphyrins (3.3.1.0.1) exhibiting strong NIR absorption are reported. The azulene transformations within the macrocycles leading to aromaticity (antiaromaticity) have been supported by DFT based theoretical investigations. Intriguingly, the nature of macrocycles with the (lack of) aromaticity of the related carbaporphyrinoids has been anticipated to be fully triggered by the type of chemically functionalized thiophene based precursor.