Porphyrinoids in the 20π-electron state have been extensively studied from the fundamental viewpoint of investigating their structure-antiaromaticity relationships. However, most of the 20π porphyrinoids are highly distorted and unstable in air, which hinder the comprehensive analysis of paratropic ring-current effects derived from planar π-electron systems. Herein, we present the first examples of antiaromatic Sn(IV) complexes of 5,10,15,20-tetraaryl-5,15-diazaporphyrinoids (SnXTADAPs), prepared by the complexation of the corresponding freebases with Sn(II) chloride under aerobic conditions and subsequent metathesis of the axial ligands, that show paratropic ring-current effects.
View Article and Find Full Text PDFDespite the significant development and extensive application of phthalocyanine and related azaporphyrins, little attention has been paid to meso-N-substituted azaporphyrinoids. Here, we report new derivatives of 5,10,20-triaryl-5,15-diazaporphyrinoids (ArDAP), which are reversibly redox-switchable between the 18π- and 19π-electron state. Four kinds of metal(II) complexes and free bases of ArDAP were prepared by metal-templated cyclization of metal(II) complexes of 5,10,15-triaryl-10-azabiladiene-ac with sodium azide or copper-catalyzed N-phenylation of 10,20-diaryl-5,15-diazaporphyrins (ArDAP) with diphenyliodonium hexafluorophosphate.
View Article and Find Full Text PDFInclusion of a heteroatom to the phosphole ring is a promising strategy to intrinsically modulate the optical properties of phosphole derivatives. We report on a series of 2-aryl-3H-1,3-benzazaphosphole oxides that were efficiently prepared via sequential C-P cross-coupling, dehydrative [3+2] cycloaddition, and ring-oxidation reactions. The inclusion of one nitrogen atom into the benzophosphole framework caused red shifting of the absorption and emission maxima, reflecting the greater stabilization of the LUMO level.
View Article and Find Full Text PDFBackground: Although endoscopic submucosal dissection (ESD) is becoming more common for early gastric cancer, it requires more advanced techniques and a longer treatment duration than endoscopic mucosal resection. Hybrid ESD using a multifunctional snare (SOUTEN) has been reported to be effective for colorectal lesions, as it can reduce treatment duration. Endoscopic suturing of post-ESD mucosal defects has been reported to reduce the incidence of ESD-related complications.
View Article and Find Full Text PDFThe fundamental properties of azaporphyrins can be modulated over a wide range by changing the number of meso-nitrogen atoms. Reported herein are the first examples of 5,10,15,20-tetraaryl-5-azaporphyrinium (MTAMAP) salts, which were prepared via metal-templated cyclization of the corresponding zinc(II) and copper(II) complexes of 10-aryl-1-chloro-19-benzoyl-5,15-dimesityl-10-azabiladiene-ac. The inclusion of one meso-nitrogen atom in the 5,10,15,20-tetraarylporphyrin skeleton considerably changes the redox and optical properties as well as the degree of aromaticity of the porphyrin ring.
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