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Published on: August 22, 2018
Pictet-Spengler Synthesis of Fused-Azepine- and 1H-Azocine-Bridged NiII Porphyrin Dimers
Yuanyuan Li1, Xiaojie Liu1, Hui Chen1
1Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, China.
Abstract:
Pictet-Spengler cyclization of meso-amino and meso, meso'-diamino β-β'-linked NiII porphyrin dimers 1Ni and 2Ni with paraformaldehyde gave fused azepine-bridged NiII porphyrin dimers 3Ni and 4Ni, respectively. Oxidation of 3Ni with FeCl3 and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) provided additionally meso-tertbuylphenyl-fused dimer 5Ni in 43% yield but the similar oxidation of 4Ni led to the formation of singly meso-tertbuylphenyl-fused dimer 6Ni in 94% yield. Fused 1H-azocine-bridged NiII porphyrin dimer 8Ni was synthesized by the similar Pictet-Spengler cyclization of meso-amino β-meso' linked NiII porphyrin dimer 7Ni. 3Ni and 4Ni were converted to the corresponding free bases and ZnII complexes, which display fairly red-shifted absorption bands and fluorescence in the near infrared (NIR) region.
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