Synthesis, Structure, and Light Absorption of Octanoyl Amino Acids

Amino acid lanthanide complexes are a promising class of environmentally friendly and non-toxic optical organic materials that find extensive applications in biomedicine, molecular probes, and optical devices. In this study, three amino acid lanthanide complexes, octanoyl glycine gadolinium (Gd(oct-ala)3×H2O), octanoyl serine gadolinium (Gd(oct-ser)3×H2O), and octanoyl phenylalanine gadolinium (Gd(oct-phe)3×H2O), were synthesized by reacting octanoyl amino acid ligands with gadolinium chloride. The coordination structure of the gadolinium complexes was determined by elemental analysis and infrared spectroscopy. XRD and polarized light microscopy confirmed the amorphous structure of the complexes. DSC and TG-DTA were used to investigate the thermodynamic stability of the gadolinium complexes, and their solubility and UV-visible light absorption properties were also evaluated. Our results demonstrate that all three gadolinium complexes exhibit excellent UV-visible light absorption performance, with the Gd(oct-phe)3×H2O containing a phenyl ring showing the highest light absorption efficiency.