SELF-OPTIMIZATION OF BINDING-SITES BY NI(II) ION ON CARBOXYPYRAZINE-CONTAINING POLY(ETHYLENIMINE)

To test the concept of self-optimization of own binding site by a meta l ion, host molecules for Ni(II) ion were built on poly(ethylenimine) (PEI) by using the ethylenediamine portions of PEI and 2-carboxypyrazi nyl (CP) group. Two derivatives of PEI containing CP were prepared: on e by random acylation of PEI with pyrazine-2,5-dicarboxylic acid mono- (2,5-dioxo-pyrrolidin-1-yl) ester (PC-DP), and the other by acylation of PEI with PC-DP in the presence of Ni(II) ion. Between these two CP derivatives of PEI, Ni(II) binding ability was more than 10(3) times g reater for the latter. Optimization by Ni(II) ion of its own binding s ite built on the polymer was attributed to the preassemblage of PC-DP and PEI with Ni(II) ion and the subsequent attack. at PC-DP by an amin o group of PEI located in an optimal position. (C) 1997 John Wiley & S ons, Inc.