2240-81-5Relevant articles and documents
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Linn et al.
, p. 2032 (1963)
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Cation-Complexing Properties of Synthetic Macrocyclic Polyether-Diester Ligands Containing the Furan, Benzene, Tetrahydrofuran, and Thiophene Subcyclic Units
Bradshaw, Jerald S.,Baxter, Steven L.,Lamb, John D.,Izatt, Reed M.,Christensen, James J.
, p. 1821 - 1827 (2007/10/02)
Thirteen new macrocyclic polyether-diester ligands containing the furan, 3,4-dimethoxyfuran, tetrahydrofuran, and thiophene subcyclic units have been prepared by reacting a diacid dichloride with the appropriate glycol.The tetrahydrofurano ligands were also prepared by reducing the furan ring of the furano ligands.Certain of these ligands and corresponding macrocyclic polyether-diester ligands containing a benzene subcyclic unit have been shown to form complexes with alkylammonium and metal cations.Complexation with alkylammonium cations was accompanied by significant chemical-shift changes on the 1H NMR spectra.Free energies of activation (ΔG) for the dissociation of the alkylammonium complexes were determined from their temperature-dependent 1H NMR spectra.The relative kinetic stability (as measured by the ΔG values) for the complexes between benzylammonium perchlorate and ligands containing an aromatic subcyclic unit increased with increasing ring size in the order 18- +, K+, Cs+, and Sr2+ with the tetrahydrofurano ligands.The complexes formed between the 18-membered ring containing a tetrahydrofuran subcyclic unit and the alkali-metal cations were about as stable as those formed from 2,6-diketo-18-crown-6 (2) but were less stable than those formed from the corresponding pyridine analogue (1).The 21- and 24-membered ring compounds containing a furan subcyclic unit were found to be effective carriers of Cs+ across a CHCl3 liquid membrane separating aqueous phases.
