Optical spectra and photophysical properties of polychlorinated dibenzo-p-dioxin derivatives

Abstract

Published data on the optical spectra and theoretical Published data on the optical spectra and theoretical investigations of dioxins, polychlorinated derivatives of dibenzo-investigations of dioxins, polychlorinated derivatives of dibenzop p-dioxin, which are well-known environmental toxins, are gener--dioxin, which are well-known environmental toxins, are generalised. The geometrical and electronic structures of the molecules alised. The geometrical and electronic structures of the molecules and their vibrational and electronically excited states are consid-and their vibrational and electronically excited states are considered. The influence of the number and positions of chlorine atoms ered. The influence of the number and positions of chlorine atoms in dioxin molecules on the optical spectra (IR and UV absorption, in dioxin molecules on the optical spectra (IR and UV absorption, fluorescence and phosphorescence spectra), in particular, on the fluorescence and phosphorescence spectra), in particular, on the low-temperature fine-structure phosphorescence spectra of solid low-temperature fine-structure phosphorescence spectra of solid solutions and on the photophysical deactivation of triplet elec-solutions and on the photophysical deactivation of triplet electronic states are discussed. The results of the use of optical tronic states are discussed. The results of the use of optical spectroscopy for identification and quantification of dioxins are spectroscopy for identification and quantification of dioxins are presented. The bibliography includes 108 references. presented. The bibliography includes 108 references.

Electronic states of dibenzo-p-dioxin. A synchrotron radiation linear dichroism investigation

“…The most harmful dioxins are believed to be halogen derivatives of dibenzo-p-dioxin (DD, Chart 1) and these compounds have attracted particular attention. The molecular and electronic structure of DD and its derivatives have thus been studied by several authors [9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

“…They computed several valence excited states by using ab initio multi-configurational CASSCF/CASPT2 theory. The predicted transitions to excited singlet states were compared with the observed near-UV absorption spectrum of DD in an isopentane matrix at 77 K [10][11][12]. However, the comparison was not entirely satisfactory and the authors produced a "theoretically fitted" curve empirically adjusted to reproduce the appearance of the observed absorbance curve [16].…”

Structural dynamic models and anharmonic analysis of vibrational states of polychloro-substituted dibenzo-p-dioxin

“…The results of an ab initio quantum calculation of the geometry of β-TCDD and OCDD are presented in Table 1. The discrepancies from the experimental data from [1] (C-O The results of theoretical analysis of the vibrational spectra of β-TCDD and OCDD, presented in Tables 2-4, allow us to draw the following conclusions.…”

“…Considering that for cyclic compounds additional relations are in effect, coupling the stretching and bending vibrational coordinates [4], the choice of an independent system of internal vibrational coordinates and consequently symmetry coordinates [4] is not unambiguous. So in comparing the system of force constants for PCDDs, it is reasonable to predefine the choice of the system of [1,10] ν h νanh * independent internal vibrational coordinates and symmetry coordinates. Such a choice for polycyclic molecules has been shown to be successful in [3] for the example of the anthracene molecule.…”

“…Ab initio quantum calculations provide a basis for re-examining the assignment made in [1] based on the classical approach [4] for a number of vibrations in OCDD according to the symmetry types B u 1 and B u 2 which are IRactive. They are marked with an asterisk (*) in Table 4. 3.…”