The crystal structure of auramine perchlorate: correlation of the results with specular reflection spectroscopy.
The x-ray analysis of auramine perchlorate has been performed in order to establish the orientation of the cationic chromophoric group in the crystal for comparison with the orientation that was proposed on the basis of specular reflection studies. The compound crystallizes with two molecules per unit cell in space group P1 and cell parameters a = 8.86 A, b = 9.69 A, c = 11.27 A, alpha = 97 degrees 40', beta = 99 degrees 34', and gamma = 106 degrees 16'. The orientation of the chromophore is in good agreement with the crystal model. Other features of the structure are the hydrogen bonding scheme of the perchlorate ion, the highly distorted chromophoric group, and the planar dimethylamine substituents.
Polarized single crystal reflection spectra of auramine perchlorate
Abstract Polarized specular reflection spectra have been obtained for three natural faces and one cleavage face of crystalline auramine perchlorate. These spectra are interpreted in terms of known solution properties through the development of a model for the orientation of the cationic dye species in the crystal and the application of classical dispersion theory. The crystal model has been further substantiated through the study of the variation of the principal directions with wavelength on each face. Various applications of reflection spectroscopy illustrated or suggested by the present work are discussed.
Electronic spectrum of 4, 4′-bis-dimethylamino fuchsone and related triphenylmethane dyes
Abstract The electronic absorption and emission spectra of 4,4′-bis-dimethylamino fuchsone (BDF) and of crystal violet (CV) have been studied using a variety of solvents and experimental conditions. Analysis of the relative polarizations of the bands leads to the conclusion that for BDF the two long wavelength transitions have erossed over relative to the ordering found in the malachite green series of dyes. These results are discussed from the point of view of the low-energy structures. The absorption intensities are calculated on this basis and the values obtained are found to be in reasonable agreement with experiment. Evidence is cited for the existence of CV in nonpolar solvents as an ion pair.