The infrared spectrum of matrix isolated guaiacol: self-association and complexation with nitrogen

Abstract

The self-association of guaiacol and guaiacol- d 3 under cryogenic matrix conditions, and the complexation with the low-temperature nitrogen matrix medium has been studied using IR spectroscopy. In the OH stretching region matrices with high M/A ratios display spectra of almost purely monomeric guaiacol. Lowering the M/A ratio results in self-association, the dominant aggregates being the dimer and the trimer. Annealing the matrix lowers the intensity of the dimer band and increases the intensity of the trimer band. Further annealing increases the relative amount of trimer and larger aggregates. The self-association tendency for guaiacol is found to be much less pronounced than for phenol. Thus the hydrogen bond in guaiacol is sufficiently strong to ensure the trapping of the molecules solely in the intramolecularly bonded form. The complexation of guaiacol with nitrogen under matrix conditions is seen as a splitting of the OH torsional transition into a multiplet, whereas the same transition in a matrix of pure argon gives rise to a single sharp band. The intensity distribution between the different bands in the torsional multiplet shows temperature dependence.