ISSN:
1573-1111
Keywords:
Crown ether-primary ammonium cation complexation
;
formation constants (K)
;
enthalpy changes (ΔH)
;
entropy changes (ΔS)
;
titration calorimetry
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Equilibrium constant (K), enthalpy change (ΔH), and entropy change (ΔS) values have been determined calorimetrically at 25°C in 90%MeOH 10%H2O (v/v) for the interactions of pyridino-18-crown-6 (P18C6) and diketopyridino-18-crown-6 (K2P18C6) with perchlorate salts of ammonium, benzylammonium,α-phenylethylammonium,β-phenylethylammonium, andα-(1-naphthyl)ethyl-ammonium cations. The crystal structure of the complex of P18C6 with benzylammonium perchlorate was determined by X-ray crystallography. The1H 1D and 2D NMR spectra of some of these complexes were used to elucidate their structural features in solution. The logK values for the interaction of the ammonium cations with P18C6 are larger than those with K2P18C6, probably due to the higher degree of structural flexibility of P18C6. Ligand K2P18C6 displays appreciable π-π interaction with theα-(1-naphthyl)ethylammonium cation, but not with theα-phenylethylammonium cation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01076667
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