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

Yapar G., ERK C.

JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHEMISTRY, cilt.42, ss.145-150, 2002 (SCI-Expanded) identifier identifier

Özet

The dibenzo[3n]crown-n were synthesised from 1,2-bis(o-hydroxyphenoxy)ethane obtained from 1,2-bis(o-formylphenoxy)ethane via Bayer-Williger oxidations with H2O2/CH3COOH in good yields. The cyclic condensation of 1,2-bis(o-hydroxyphenoxy)ethane with dichlorides, and ditosylates of polyethylene glycols in DMF/Me2CO3 gave the macrocycles dibenzo[15]crown-5, dibenzo[18]crown-6,dibenzo[21]crown-7 and dibenzo[24]crown-8. The structures were identified using IR, mass, H-1 and C-13 NMR spectroscopy. The recognition of the molecules for the cations, Li+, Na+, K+, Rb+ and Zn2+ were conducted quantitatively with steady state fluorescence spectroscopy. The 1: 1 association constants in acetonitrile showed a good relation of the appropriate size of the macrocyclic ether towards the fitting cation radii. Namely, dibenzo[15]crown-5 was the best for Li+ binding and more than 100 times better than Na+ and K+. Dibenzo[21]crown-7 was excellent for Rb+ binding while K+ is 100 times less preferred. The largest crown ether studied, dibenzo[24]crown-8, exhibited the order of binding power, Rb+ > K+ > Na+. Zn2+ displayed, however, a marked binding with only dibenzo[18]crown-6.