Bis(azobenzene)-based photoswitchable, prochiral, C-alpha-tetrasubstituted alpha-amino acids for nanomaterials applications

Two new C(alpha)-tetrasubstituted alpha-amino acids, each characterized by the presence of two identical azobenzene- derived side chains, have been synthesized and found to exhibit photoreversible isomerization properties. A detailed analysis revealed the formation of intermediate chiral species during the isomerization process driven by light. These intermediate species were unambiguously detected as diastereomers when the bis(azobenzene)-containing amino acid was coupled to a chiral protein amino acid. Supramolecular systems formed by conjugation of one of the bis(azobenzene)-derived amino acids with different metal nanoparticles have been shown to retain the reversible photoswitch properties. Furthermore, the Au-derived nanoparticles exhibit a magnetic susceptibility dependence on the light-driven isomerization state that can be simply detected by 1H NMR spectroscopy. Based on this behavior, these amino acids are of relevant potential for the development of a novel class of materials.