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Porphyrin-Stabilized Nitrenium Dication
摘要： Azepine-fused NiII-porphyrin dimer was synthesized by oxidative amination of b–b linked NiII-porphyrin dimer and its N-aryl congener was synthesized by two-fold Buchwald–Hartwig amination of b-to-b linked and dichlorinated NiII-porphyrin dimer. Oxidation of the NH congener gave neutral aminyl radical and nitrenium ion successively in a similar manner to the previously reported NH-bridged NiII-porphyrin dimer. On the other hand, oxidation of the N-aryl congener afforded formal nitrenium dication in a single-step two-electron oxidation. Stable nitrenium dications are rare that are isoelectronic to neutral trivalent boron compounds and tertiary carbocations. The chemical stability of the nitrenium dication has been improved by chlorine substitution at the most reactive b-position. The structural, optical, magnetic, electrochemical properties of these compounds mentioned above have been fully characterized.
关键词： dication,aminyl radical,nitrenium ion,azepine,porphyrin dimer
更新于2025-09-23 15:21:01
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Selective Formation of Helical Tetrapyrrin‐fused Porphyrins by Oxidation of beta‐to‐beta Linked meso‐Aminoporphyrin Dimers
摘要： Oxidation of b-to-b directly linked and sulfur-bridged meso-amino NiII-porphyrin dimers with PbO2 gave helical tetrapyrrin (biliverdin analogue)-fused NiII-porphyrins. These ring cleaving reactions differ markedly from the previously reported oxidation of a b-b linked NiII-porphyrin dimer carrying one amino-group that gave an azepine-fused porphyrin dimer. The tetrapyrrin-fused NiII-porphyrins display intense NIR absorption bands reaching at 1200–1400 nm and reversible redox processes because of the highly p-conjugated networks and rigid structures. These tetrapyrrin-fused NiII-porphyrins were separated to stable enantiomers, which showed clear Cotton effects in their CD spectra with De of 102 order.
关键词： NIR absorption,aminyl radical,helical structure,p-extended porphyrin,circular dichroism
更新于2025-09-04 15:30:14