Dual Emission of a Free‐Base 5‐Oxaporphyrinium Cation from its cis‐ and trans‐NH Tautomers
Dual Emission of a Free‐Base 5‐Oxaporphyrinium Cation from its cis‐ and trans‐NH Tautomers
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顺式和反式 NH 互变异构体的游离碱 5-氧代卟啉鎓阳离子的双重发射
DOI：
10.1002/anie.202013542
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Shinokubo Hiroshi
中科院分区：
文献类型：
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作者：
Takiguchi Asahi;Kang Seongsoo;Fukui Norihito;Kim Dongho;Shinokubo Hiroshi
用杂原子取代卟啉的中位次甲基碳原子是调节其光学和电子性质的有力策略。特别是，5-氧代卟啉是一个有吸引力的目标，由于其作为血红素catalysts中间体的重要性。在这项工作中，我们描述了一种游离碱5-oxaporphyrinium阳离子的合成和性质，它是通过用三氟甲磺酸酐闭环bilindione制备的。这种游离碱5-氧代卟啉阳离子表现出源自其独特的NH互变异构的双重荧光。与正常的卟啉相反，5-氧代卟啉阳离子的顺式形式比反式形式更稳定，这是由于其正电荷的有效离域。因此，我们在这里证明，meso-修饰的杂卟啉能够操纵卟啉大环中的NH互变异构。
Replacement of the meso methine carbon atoms of porphyrins with heteroatoms is a powerful strategy for tuning their optical and electronic properties. In particular, 5‐oxaporphyrin is an attractive target due to its importance as an intermediate in heme catabolism. In this work, we describe the synthesis and properties of a free‐base 5‐oxaporphyrinium cation, which was prepared by the ring‐closure of a bilindione with trifluoromethanesulfonic anhydride. This free‐base 5‐oxaporphyrinium cation exhibits dual fluorescence originating from its unique NH tautomerism. In contrast to normal porphyrins, the cis form of the 5‐oxaporphyrinium cation is more stable than the trans form due to the effective delocalization of its positive charge. We thus demonstrate here that meso‐modified heteroporphyrins enable the manipulation of NH tautomerism in porphyrinic macrocycles.