Photoelectron spectra of intramolecularly hydrogen bonded compounds

Abstract

The photoelectron spectra of a series of intramolecularly hydrogen bonded compounds have been studied at several temperatures along with the spectra of their nonhydrogen bonded analogs. The hydrogen bonded compounds studied were 2-aminoethanol, 3-amino-1-propanol, N, N-dimethyl-2-aminoethanol, N,N-diethyl-2-aminoethanol, N,N-dimethyl-3-amino-1-propanol, N,N-diethyl-3-amino-1-propanol, and 2-iodoethanol. The nonhydrogen bonded analogs include 2-methoxyethylamine, 3-methoxypropylamine, and 2-methoxyethyl iodide. The spectra were studied at 23 and at 200 °C with a few also examined at intermediate temperatures. It was observed in all the hydrogen bonded compounds that the ionization potential of the electron donor, i.e., N or I was temperature dependent, and decreased with increasing temperature. The ionization potentials of these compounds were markedly greater than the values for the nonbonded analogs. This difference is interpreted to be due to the stabilization energy of the lone pair involved in hydrogen bonding. In two of the systems, N,N-dimethylaminopropanol and N,N-diethylamino-propanol, the oxygen band also appeared temperature dependent. In these more strongly hydrogen bonded systems, hydrogen bond formation was interpreted to affect the electronic charge density on the oxygen with consequent effects on the oxygen ionization potential. © 1973, The American Institute of Physics. All rights reserved.