294. The application of infra-red spectroscopy to structural problems in the anthraquinone field

Abstract

Some possible applications of infra-red spectroscopy in the anthraquinone field have been examined. In most cases the compounds were examined as solids, on account of their limited solubility and the possibility of molecular rearrangements in solution. Although complete interpretations of the spectra are not possible, information has been gained about the finer details of the structures of various quinones of known constitution, from measurements of the frequencies of bands associated with carbonyl, hydroxyl, amino-, and other groups. The hydrogen bonding in hydroxyquinones has been examined. An interesting resonance phenomena is observed in aminoanthraquinone derivatives. The spectra of certain benzamido-and acetamido-quinones in the solid state show anomalies. The use of infra-red spectroscopy in identifying reduction products of unknown constitution has been assessed, by examining various authentic anthrones, oxanthrones, etc.Leucoquinizarin and the stable leucocompound of 1 : 4-diaminoanthraquinone have been examined.This application shows promise.

Spectroscopic studies of the mechanism of reversible photodegradation of 1-substituted aminoanthraquinone-doped polymers

“…Note that there is no change from the other C− −O group of the 1AAQ molecule at 1667 cm -1 [108], which is consistent with the conclusion obtained from the linear absorption spectroscopy measurements and the TD-DFT calculations in DO11. The reduction in IR peaks of PMMA after irradiation provides evidence of polymer degradation, which supports the PTCR hypothesis.…”

“…The peak at 1546 cm -1 can be assigned to the in-plane NH 2 scissoring of 1AAQ, though is 34 cm -1 lower wavenumbers than the usual frequency range in organic compounds [105], which could be caused by the intramolecular hydrogen bond. The band at 1608 cm -1 can be attributed to the vibration of C− −O adjacent to the amine group [108] of 1AAQ. It is worth noticing that there is no change in the band at 1667 cm -1 , which can be assigned to the vibration of the other C− −O group of the 1AAQ molecule [108] and is observed in Figure 12 (therefore not labeled in the figure).…”

“…The band at 1608 cm -1 can be attributed to the vibration of C− −O adjacent to the amine group [108] of 1AAQ. It is worth noticing that there is no change in the band at 1667 cm -1 , which can be assigned to the vibration of the other C− −O group of the 1AAQ molecule [108] and is observed in Figure 12 (therefore not labeled in the figure). The symmetric and asymmetric N−H stretching modes of the amine group at about 3320 cm -1 and 3440 cm -1 [108] are too noisy to determine whether they changed after irradiation.…”

“…The peak at 1464 cm -1 is known to be the CH 2 scissoring band of hydrocarbons [105,109]. The band at 1716 cm -1 originates from the C− −O stretching vibration [105] but not from the aminoanthraquinones, which possess a C− −O stretch frequency of 1610∼1680 cm -1 [108], nor from PMMA, which exhibits a C− −O stretch near 1731 cm -1 [110]. The change of IR absorption bands between 2850 and 3000 cm -1 are known to be the sp 3 CH stretching vibration [105,109].…”

Infrared Spectroscopic Investigations of Effect of Strong Resonance Stabilized Intramolecular Hydrogen Bonding in 1-(1-Hydroxy-2-naphthyl)-3-(phenyl or Substituted phenyl)-prop-2-en-1-ones and on their Complexation with Some Transition Metals

“…Careful examination of the spectrum of o-hydroxyacetophenone indicates the absence of any band characteristic of free hydroxyl group. Similar behaviour was previously noted in the o-hydroxyanthraquinones 59 and it was attributed to intramolecular hydrogen bonding. However, in 2-acetoxyacetophenone, the acylated product of o-hydroxyacetophenone, the carbonyl band is shifted back to higher frequency.…”