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Thermodynamic Study of Dihydrogen Phosphate Dimerisation and Complexation with Novel Urea‐ and Thiourea‐Based Receptors
Author(s) -
Bregović Nikola,
Cindro Nikola,
Frkanec Leo,
Užarević Krunoslav,
Tomišić Vladislav
Publication year - 2014
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.201404091
Subject(s) - thiourea , chemistry , isothermal titration calorimetry , acetonitrile , moiety , urea , dimethyl sulfoxide , inorganic chemistry , titration , sulfoxide , phosphate , affinities , solvent , organic chemistry , stereochemistry
Complexation of dihydrogen phosphate by novel thiourea and urea receptors in acetonitrile and dimethyl sulfoxide was studied in detail by an integrated approach by using several methods (isothermal titration calorimetry, ESI‐MS, and 1 H NMR and UV spectroscopy). Thermodynamic investigations into H 2 PO 4 − dimerisation, which is a process that has been frequently recognised, but rarely quantitatively described, were carried out as well. The corresponding equilibrium was taken into account in the anion‐binding studies, which enabled reliable determination of the complexation thermodynamic quantities. In both solvents the thiourea derivatives exhibited considerably higher binding affinities with respect to those containing the urea moiety. In acetonitrile, 1:1 and 2:1 (anion/receptor) complexes formed, whereas in dimethyl sulfoxide only the significantly less stable complexes of 1:1 stoichiometry were detected. The solvent effects on the thermodynamic parameters of dihydrogen phosphate dimerisation and complexation reactions are discussed.