Canadian Journal of Chemistry

Strong cooperative protonation of a small tris-urea cryptand

PG Potvin, MH Wong

Index: Potvin, Pierre G.; Wong, Man Hung Canadian Journal of Chemistry, 1988 , vol. 66, p. 2914 - 2919

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Citation Number: 15

Abstract

A small bicyclic cryptand 3 bearing urea groups along the 7-atom bridges was synthesized in 22% yield by a novel tripod-tripod coupling procedure. Protonation and complexation studies are reported and compared with results with polyoxa-[2]-cryptands and [3]-cryptand 6. These show that 3 is a moderate base, a weak metal ion binder, but a two-proton binder exhibiting strong positive cooperativity (p K a2> p K a1) and fast proton exchange kinetics. ...