Tetrazole as a Carboxylic Acid Isostere and the Synthesis of All Amine-Based Polyampholytes

A new family of polyampholytes (PAMs) is described in which both the basic and acidic groups are based on nitrogen functional groups. Reversible addition-fragmentation chain transfer-prepared poly(pentafluorophenyl acrylate) is quantitatively modified sequentially with 3-picolylamine and 5-aminotetrazole, yielding the new well-defined statistical PAMs. Successful formation of the PAMs is confirmed via a combination of F-19 and C-13 NMR spectroscopy and FTIR. Aqueous electrophoresis indicates isoelectric points (pI) between 2.9 and 4.4 depending on copolymer composition. However, the pI is somewhat insensitive to the copolymer composition, a feature attributed to the similarity of the pK(a)s of the acid tetrazole species and the conjugate acid of the pyridyl repeat units.

Automated summary

A new family of polyampholytes (PAMs) with nitrogen functional groups as both the basic and acidic groups is described. The synthesis of the well-defined statistical PAMs is confirmed through various spectroscopic techniques. Aqueous electrophoresis results indicate the isoelectric points (pI) of the PAMs, which are somewhat insensitive to the copolymer composition.