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Amphoteric Homotropic Allosteric Association between a Hexakis‐Urea Receptor and Dihydrogen Phosphate
Author(s) -
Kondo Seiya,
Masuda Junya,
Komiyama Tomoki,
Yasuda Nobuhiro,
Takaya Hikaru,
Yamanaka Masamichi
Publication year - 2019
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.201904241
Subject(s) - allosteric regulation , chemistry , urea , phosphate , hydrogen bond , bromide , intramolecular force , medicinal chemistry , benzene , molecule , inorganic chemistry , stereochemistry , organic chemistry , enzyme
Conformationally flexible hexakis‐urea 1 was synthesized efficiently by condensing hexakis(aminomethyl)benzene with 4‐nitrophenyl‐(3,5‐di‐ tert ‐butylphenyl)carbamate. The hexakis‐urea 1 is unexpectedly soluble in organic solvents of low polarity due to intramolecular hydrogen bonding. The hexakis‐urea 1 recognizes chloride, bromide, and acetate in a 1:2 host‐guest ratio and in a positive allosteric manner in CDCl 3 . The ability of 1 to recognize dihydrogen phosphate is a unique outcome, and the structure of the associated complex, which contains four dihydrogen phosphate ions, was clarified by single‐crystal X‐ray structural analysis. However, in solution, a complex with three dihydrogen phosphate ions was identified. The dihydrogen phosphate association in CDCl 3 proceeds in an amphoteric allosteric manner; in a positive allosteric manner ( K 1 < K 2 ) in the first step and a negative allosteric manner ( K 2 > K 3 ) in the subsequent step.