Synthesis, Characterization, and Photophysical Properties of a Free Base and a Biszinc(II) Complex of 1,3-Bisporphyrincalix[4]arene: Evidence for "Tunable Intramolecular Open and Closed Conformations"

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• 作者：Jean-Philipe Tremblay-Morin ; Sé ; bastien Faure ; Dalila Samar ; Christine Stern ; Roger Guilard ; and Pierre D. Harvey
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：April 18, 2005
• 年：2005
• 卷：44
• 期：8
• 页码：2836 - 2842
• 全文大小：241K
• 年卷期：v.44,no.8(April 18, 2005)
• ISSN：1520-510X

文摘

The bismacrocycle 5,17-bis[5-(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrinyl)]-25,26,27,28-tetrapropoxycalix[4]arene (4) was synthesized in three steps from the corresponding bisaldehyde 5,17-diformyl-25,26,27,28-tetrapropoxycalix[4]arene. The biszinc(II) complex (5) was prepared as well, and the photophysical properties weremeasured using 2-MeTHF as solvent at 298 and 77 K. While computer modeling for 5 predicts that both pinchedcone conformers, closed (porphyrins near each other) and open (porphyrins away from each other), may exist inthe "gas phase", the experimental data indicate clearly that no zinc porphyrin···zinc porphyrin interactions arepresent in solution at 298 K, favoring the open conformer, where the two macrocycles are placed away from eachother. On the other hand, clear evidence for a closed conformer is observed at 77 K. Variable-temperature ¹HNMR experiments show that 5 is fluxional between 298 and 183 K, while 4 keeps the open conformation for thewhole temperature range. This behavior is unprecedented for calix[4]areneporphyrin compounds, and the relativeporphyrin ring rigidity is postulated to explain this difference.