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Thermodynamic Study on the Effect of O2N2-azacrown Macrocyclic Ring-size in Complexation with [60]Fullerene
Ist Teil von
Fullerenes, nanotubes, and carbon nanostructures, 2013-01, Vol.21 (5), p.394-402
Ort / Verlag
Philadelphia, PA: Taylor & Francis Group
Erscheinungsjahr
2013
Link zum Volltext
Quelle
Taylor & Francis
Beschreibungen/Notizen
The interaction of [60]fullerene with a series of 15-19-membered macrocycles containing an O
2
N
2
-donor set has been investigated by UV-visible spectroscopy. The formation constants arising from the complexation of [60]fullerene with these azacrown macrocycles, having various ring size, were determined in CHCl
3
media applying Benesi-Hildebrand equation. The stoichiometry has been found by the Job method in each case. The thermodynamic parameters, for example, formation enthalpies (ΔH
o
) and entropies (ΔS
o
), for these complexation were also determined. Experimentally, it was found that macroring size of the azacrown has a prominent effect on azacrown complexation with [60]fullerene in terms of their association constants (K). The best K value was measured for 18-membered ring size in which a 1:1 complexation with [60]fullerene was dominant. Monitoring this complexation by
1
H NMR spectroscopy, the chemical shift changes recorded for CH
2
groups on the macroring introduced its nitrogen groups as the main interaction sites.