The π–π* electronic absorption spectra of 1-amino-, 1,4-diamino-, and 1,4,5,8-tetraaminoanthraquinones were investigated by means of the polarized absorption spectra using stretched PVA sheets and theoretical calculations. Each of these compounds has four absorption bands in the near-ultraviolet region (210–340 nm) and one in the visible region. The bands of the aminoanthraquinones which appear in the visible region can be assigned to the intramolecular charge-transfer transitions associated with the charge migration from the ami no group to the carbonyl groups.
Vibronic π-π* transition bands of pyrene, 4,5-dihydropyrene (DHP), and 4,5,9,10-tetrahydropyrene (THP) were assigned by means of dichroism analysis using stretched poly(vinyl alcohol) films. The absorption spectra of the samples in the non-stretched films were divided into two component spectra polarized along the long (x) and short (z) axes of the molecular plane. For pyrene, in addition to the four conventionally-assigned band systems (1Lb, 1La, 1Bb, and 1Ba), some forbidden bands were found in the respective band regions. Most of the vibronic DHP and THP bands were also reasonably well assigned from comparisons with the calculated results for phenanthrene and biphenyl, respectively.
Absorption, emission and excitation spectra of heat-treated PVA film have been interpreted as corresponding to mixtures of –(CH=CH)n– and –(CH=CH)n–CO–, which are distinguishable from each other according to whether spectrum is accompanied with fine structures or not. The former shows fine structures and has had n determined to be 2–14 by analysis of peak locations on the basis of linearity for Lewis-Calvin’s plot. For the latter, n has been determined to be 1–7, and Lewis-Calvin’s plot between the wavelength of band maximum and n also shows a good linearity.
1) An expression for the optical density ratio was derived as a function of the stretch ratio.
2) Dichroism of the crystal violet and auramine yellow ion in stretched PVA sheets was observed, and the relation of the optical density ratio to the stretch ratio was plotted. It was shown that the theoretical expression derived here could explain rather well the experimental relation between these two quantities.
3) The analytical results were as follows. The main absorption band and the shoulder of the crystal violet ion did not orginate from the two isomers but were perhaps due to one species. For the auramine yellow ion the angle between the transition directions corresponding to the first and the second band might be approximately a right angle provided that the absorption-planes were in a same plane.
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