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Remarkably Selective Recognition of Iodobenzene Derivatives by a Macrocyclic Bis‐Pt II Metallohost
Author(s) -
Trokowski Robert,
Akine Shigehisa,
Nabeshima Tatsuya
Publication year - 2011
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.201101650
Subject(s) - chemistry , stacking , selectivity , non covalent interactions , aromaticity , heteronuclear molecule , steric effects , stereochemistry , halogen , crystallography , molecule , nuclear magnetic resonance spectroscopy , hydrogen bond , organic chemistry , catalysis , alkyl
We designed and synthesized self‐assembled bis‐Pt II dimer 1⋅ 4 BF 4 with quino[8,7‐ b ][1,10]phenanthroline as an extended π‐face contact area, which acts as the first artificial receptor with high affinity toward iodinated aromatic compounds significantly based on noncovalent iodine ⋅⋅⋅ aromatic‐plane interactions in a “side‐on” fashion. Despite their structural similarity to a previously reported metallohost 2 4+ that bears 2,2′:6′,2′′‐terpyridine units, a dramatic change in selectivity toward substituted benzene derivatives was observed for 1 4+ . 1 H NMR spectroscopic titration revealed a high affinity of 1 4+ towards haloarenes, with exceptionally large association constants for 2‐iodophenol ( K a =16 000 M −1 ) and 1,2‐diiodobenzene ( K a =21 000 M −1 ), which are 93‐ and 140‐fold higher, respectively, than the values obtained for 2 4+ . In addition, 1 4+ showed a remarkably high affinity and selectivity toward 2,6‐diiodophenol ( K a =35 000 M −1 ), which is an important substructure of the thyroid hormone T 4 . X‐ray crystallography and theoretical calculations strongly suggest that “side‐on” iodine ⋅⋅⋅ aromatic‐plane interactions and π–π stacking contribute to the strong 1,2‐diiodobenzene and 2,6‐diiodophenol binding. The results obtained here give unique and valuable insight into the nature of halogen atom interactions in their “side‐on” region with an electropositive aromatic plane, which may provide useful guidance for designing artificial receptors for iodinated biomolecules.