Vibrational spectroscopy and DFT calculations of amino acid derivatives: N-acetyl-L-Asp and N-acetyl-L-Glu in the solid state

Experimental vibrational spectroscopic studies and density functional theory (DFT) calculations of the amino acid derivatives N-acetyl-L-Asp and N-acetyl-L-Glu have been undertaken. Raman and IR spectra have been measured in the solid state for both molecules. DFT simulations were conducted using the B3-LYP correlation functional and the cc-pVDZ basis set in order to determine their energy minimized/geometry optimized structures (based on a single isolated molecule in the gaseous state), and vibrational spectra were computed at the optimized geometry in each case. Normal coordinate calculations have provided vibrational assignments for fundamental modes, including their potential energy distributions. Significant differences are observed in the computed structures and in the vibrational spectra of N-acetyl-L-Asp and N-acetyl-L-Glu. The combination of experimental and calculated results provides an insight into the structural and vibrational spectroscopic properties of N-acetylated amino acid derivatives. Copyright (C) 2009 John Wiley & Sons, Ltd.