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Gold‐Clip‐Assisted Self‐Assembly and Proton‐Coupled Expansion–Contraction of a Cofacial Fe III –Porphyrin Cage
Author(s) -
Wang Yuanyuan,
Ang Pau Lin,
Wong ChunYuen,
Yip John H. K.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201803501
Subject(s) - porphyrin , chemistry , crystallography , cage , anthracene , free base , photochemistry , salt (chemistry) , mathematics , combinatorics
A molecular cage {Au 8 (μ‐PAnP) 4 [Fe(H 2 O) 2 (TPyP)] 2 (OTf) 2 }(OTf) 8 ( 1 ) composed of two cofacial Fe III ‐porphyrin can be self‐assembled from the gold clip [Au 2 (PAnP)Cl 2 ] and Fe 3+ (H 2 O) 2 (TPyP) + (PAnP=9,10‐bis(diphenylphosphino)anthracene, TPyP= meso ‐tetra(4‐pyridyl)porphyrinato). The height of the cage is 8.579(3) Å. The addition of a base to a solution of the cage leads to a contracted and twisted cage {[Au 8 (μ‐PAnP) 4 [Fe 2 (μ‐O)(TPyP) 2 ]}(OTf) 8 ( 2 ), which has a height of ≈4.4 Å and porphyrin–porphyrin torsional angle of ≈20°. The contracted cage can be synthesized independently from the gold clip and Fe 2 (μ‐O)(TPyP) 2 . The spectroscopy and crystal structure of an unclipped analog of the contracted cage, {[AuPPh 3 ) 8 [Fe 2 (μ‐O)(TPyP) 2 ]}(OTf) 8 ( 3 ), supports the DFT‐calculated structure of 2 . NMR and UV/Vis titrations show that the expansion‐untwisting and contraction‐twisting of the cage is reversible.