Thermal chemiluminescence spectroscopy of amino acids and its salts using a multichannel Fourier-transform spectrometer

The thermal chemiluminescence spectra of the dicyclohexylamine (DCHA) salts of glycine, alanine, serine, and threonine were measured with a multichannel Fourier-transform chemiluminescence (FT-CL) spectrometer. The zwitterionic amino acids themselves are non-luminescent because their amine groups are protonated, whereas the corresponding DCHA salts show strong emission in the presence of oxygen because their NH2 groups are free. It was found that the CH3 and OH groups on the side chain caused red and blue shifts, respectively, suggesting that thermal luminescence spectroscopy using an FT-CL spectrometer can be used to identify the presence of electron donating or withdrawing groups in chemiluminescent molecules.