Annulation reactions of the butadiyne-bridged carbazole dimer 1 produced carbazole-based chalcogenaisophlorins 2-4, which were transformed into the corresponding palladium complexes 2Pd-4Pd. The structures were characterized by NMR spectroscopy and X-ray diffraction analysis. Metallation fixed the structures which displayed weak antiaromatic character derived from the 20π isophlorin framework. These complexes showed weak near-infrared (NIR) absorption typical for antiaromatic porphyrinoids in solution. In addition, 2Pd and 3Pd showed relatively strong solid-state NIR absorption. X-ray diffraction analyses of 2Pd and 3Pd revealed trimeric and dimeric stacked layered structures, respectively, and DFT calculations suggest that the solid-state NIR absorption is ascribed to intermolecular charge transfer.
- NIR absorption
- density functional calculations
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