Density Functional Theory Study of Cu₆ Nanoclusters as a Phenylalanine Detector

Research on amino acids is an attractive area because of their application in metabolism, cancer treatment, growth, and repair of body tissue, and RNA and DNA syntheses. Twenty amino acids are primarily responsible for protein synthesis. In our study, we used a Cu₆ nanocluster as an amino acid detector. For the investigation, we adsorbed amino acids on the Cu₆ nanocluster and studied their UV-visible spectra. It is observed that all of the Cu₆-amino acid complexes have peaks at near 380 nm wavelength except the Cu-phenylalanine complex, where two UV-visible peaks are found at wavelengths 351 nm (excitation energy 3.49 eV) and 403 nm (excitation energy 3.02 eV), respectively, which originated from the HOMO - 2 to LUMO (28%) and HOMO - 1 to LUMO (38%) transitions. Due to this unique transition, the Cu₆ nanocluster can be used for the detection of the phenylalanine amino acid out of the 20 amino acids.