MICELLE-LIKE GLOBULAR POLYBASES OF THE PARTIALLY QUATERNIZED POLY[THIO-1-[(N-R1-N-R2-AMINO)METHYL]ETHYLENE] TYPE AS CATALYSTS FOR CHEMICAL MODIFICATION OF HYDROPHOBIC SUBSTRATES IN WATER

In aqueous media, bifunctional polybases of the partially quaternized poly[thio-1-[(N-R1-N-R2-amino)methyl]ethylene] type (Q-P(TN-R1-N-R2,AE)X, with X = percentage of N-quaternization) take on a globular conformation, an extended-coil conformation, or both at equilibrium, depending on the ionization state of tertiary amine residues and on a globule-to-coil cooperative transition of the all-or-none type. It has been previously shown that micelle-like globules are able to catalyze the hydrolysis of N-CBZ-L-leucine p-nitrophenyl (PNP) ester in water at neutral pH with rate increases as high as several thousand times with respect to polymer-free solutions buffered at the same pH. To show the versatility of this catalytic activity, several compounds, namely, PNP esters of various aliphatic carboxylic acids with increasing chain length, (3-methyl-2-cyclohexenylidene)laurylamine (3-MCHLA), 2,4-dinitrochlorobenzene (DNC), and N-CBZ-L-leucine (CBZLeu), were allowed to react in water in the absence and in the presence of Q-P(TN-R1-N-R2,-AE)15 macromolecules, with R1 = R2 = ethyl or R1 = methyl and R2 = sec-butyl, in the globular or extended-coil forms. In all cases, globules showed outstanding catalytic activities which were tentatively assigned to the distinct medium formed in water by the core of the globules. It was further shown that ionization of dyes dissolved within the core is higher than in polymer-free water at the same pH. Therefore, it was concluded that the core of the globules acts as a superbasic medium with respect to water.