Novel methods of synthesis of dibenzo[3n]crown-n and their cation binding studied by fluorescence spectroscopy. Part V


Yapar G., ERK C.

JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHEMISTRY, vol.43, pp.299-303, 2002 (SCI-Expanded) identifier identifier

Abstract

The dibenzo[3n] crown-n were synthesised starting from bis[2-(o-hydroxyphenoxy) ethyl] ether obtained from bis[ 2-(o-formylphenoxy) ethyl] ether via Baeyer-Villiger oxidation in H2O2/CH3COOH in a good yield. The cyclic condensation of bis[2-(o-hydroxyphenoxy) ethyl] ether with tri- and tetraethylene glycol bisdichlorides and the bisditosylate of pentaethylene glycol in DMF/Me2CO3 afforded the large cyclic ethers of dibenzo[21] crown-7, dibenzo[24] crown-8 and dibenzo[27] crown-9. The structures were analysed with IR, H-1 NMR, C-13 NMR and low-resolution mass spectroscopy methods. The Na+, K+, Rb+ and Cs+ cations' recognition of the molecules were conducted with steady-state fluorescence spectroscopy. The 1: 1 association constants, K-a, in acetonitrile were estimated. Dibenzo[ 21] crown-7 was the best both for K+ and Rb+ binding but showed too small an effect on Cs+. Dibenzo[24] crown-8 exhibited the binding power in the order of Rb+ > K+ > Na+ > Cs+. However, dibenzo[27] crown-9 displayed marked binding with only K+ but not with Rb+ or with Cs+ cations probably due to the heavy atom effect of fluorescence quenching.