Poly(dipeptamidinium)‐Salze: Definition und Methoden zur präparativen Herstellung

Abstract

Poly(dipeptamidinium) Salts: Definition and Methods of Preparation Poly(dipeptamidines) are polypeptide derivatives in which the carbonyl oxygen of each second backbone amide group is replaced by an imine nitrogen (see A). So far, such derivatives have been unknown. Polyprotonated salts of them ( = poly(dipeptamidinium) salts) are of interest in view of their intrinsic constitutional relationship to the structure of polynucleotides: the number of covalent bonds between neighboring centers of positive charge in poly(dipeptamidinium) salts is identical to the number of covalent bonds between neighboring centers of negative charge in natural polynucleotides (see D). Poly(dipeptamidinium) polycations and polynucleotide polyanions are constitutionally and electrostatically complementary structures. Since poly(dipeptamidines) are (formally) polymers of dipeptide nitriles, and, since they can be expected to give polypeptides on hydrolysis, the relationship mentioned above deserves attention and experimental study in context with the problem of designing chemical models of biogenesis. This paper describes methods for the chemical preparation, the spectral characterization, and some chemical properties of homodipeptidic poly(dipeptamidinium) salts in the L‐alanyl‐glycyl and L‐phenylalanyl‐glycyl series. The methods of preparation include a stepwise construction of defined lower oligomers (up to hexamer) as well as, in the L‐alanyl‐glycyl series, a one‐operation poly‐condensation procedure leading to polymers containing an average of ca. 20 dipeptamidinium units (Schemes 4,6 and 7).