Unusual hygroscopic pseudopeptide from alanine-arginine and their Cu(II) complexes

A stepwise synthesis of a pseudopeptide containing an arginine group was performed, which causes the unusual property of hygroscopicity to appear instantly in air. This somewhat impedes characterization of this pseudopeptide, but its extreme solubility in water ensures that it can be studied in solution and its protonation and complex formation constants with cations such as Cu(II) can be determined. The synthesized compound behaves as a binucleating ligand according to the determined constants. The presence of the amino acids used (alanine and arginine) was determined by qualitative assays of functional groups, providing useful information for teaching organic synthesis in low-resource facilities.