Novel benzoyl amino acid derivatives: High-efficiency synthesis, characterization, and application in anti-UVC polylactic acid films

Amino acid derivatives are widely designed and synthesized as UV absorbers for Anti-UV applications due to their green nature, non-toxicity, and renewability. However, there are still certain challenges in the systematic research on their high-efficient synthesis and exploring new application areas. Herein, nine novel benzoyl amino acid derivatives were synthesized via a solution-phase reaction using three amino acids (glycine, alanine, and phenylalanine) and benzoyl-based compounds. The molecular structures were confirmed by 1 H NMR, 13 C NMR, MS and FTIR spectroscopy. SEM revealed their block and rod-like microstructures and XRD confirmed low crystallographic symmetry. DSC and POM indicated melting points near 150 °C and optical anisotropy upon heating. UV-Vis and photoluminescence spectra demonstrated strong optical absorption and blue-to-green emission. The synthesized derivatives were optimized with frequency analyses at the M062X/6-311g(d,p) level. These optimized structures were further characterized by different quantum chemical approaches. A biodegradable transparent film was prepared by embedding the derivatives into polylactic acid via solution casting. The resulting film exhibited excellent UV-shielding performance in the 190-290 nm range, with a maximum interception rate of 97.09 %. These results provide an important theoretical basis for the development of new amino acid derivatives and membrane materials with biodegradable properties and excellent UV-shielding performance.