SYNTHESIS AND ENHANCED CHEMILUMINESCENCE OF NEW CYCLOMALTOOLIGOSACCHARIDE (CYCLODEXTRIN)-BOUND 6-PHENYLIMIDAZO[1,2-A]PYRAZIN-3(7H)-ONE

In order to provide chemiluminescent substrates that have high light-e mitting efficiency in aqueous solution, the structural design on 6-phe nylimidazo[1,2-a]pyrazin-3(7H)-one compounds was studied in the covale nt attachment of a light-producing chromophore to a cyclomaltooligosac charide (cyclodextrin). The synthesis of cyclodextrin-bound 6-phenylim idazo[1,2-a]pyrazin-3(7H)-one compounds was achieved by the formation of an amido bond between a 6-phenylimidazo[1,2-a]pyrazin-3(7H)-one and a mono-6-amino-6-deoxycyclodextrin, The properties of oxygen-induced chemiluminescence of the synthesized cyclodextrin-bound light-emitting chromophores were investigated. The light-emitting efficiency in pH 8 .3 phosphate buffer was remarkably dependent on the kind of bound cycl odextrin and the binding site between the chromophore and cyclodextrin . The light-emitting efficiency of a cyclodextrin-bound compound in wh ich cyclomaltoheptaose(beta-cyclodextrin) had been covalently attached to the 2-position of the imidazo[1,2-a]pyrazin-3(7H)-one ring system showed an up to 11-fold enhancement over that of a non-cyclodextrin ch romophore, whereas attachment to cyclomaltohexaose(alpha-cyclodextrin) resulted in no enhancement. Moreover, this study indicated that the s trategy that involves covalently attaching a light-producing chromopho re onto a cyclodextrin for the enhancement of chemiluminescence is mor e efficient than the use of an aqueous solution containing very large amounts of cyclodextrin. (C) 1998 Elsevier Science Ltd. All rights res erved.