Redox properties of Bis-Triarylamines and ligand properties of Thianthrenophane
type: CreativeWork
description: The one electron oxidation potential of ten TAAs with all permutations of Cl , OMe- and Me-substituents in the three p-positions were determined by CV. The half wave potential of the first oxidation wave correlates linearly with the number of Cl- and OMe-substituents. AM1-CISD derived values of the absorption energies are in good agreement with the experiments but differ strongly for the oscillator strengths as well as for neutral compounds and their corresponding mono radical cations. The small solvent dependence of the experimental UV/Vis spectra in CH2Cl2 and MeCN reflects a minor charge transfer character of the electronic transitions. The UV/Vis/NIR spectra of the series of TAAs and their corresponding radical cations and the AM1 computations reveal that even small substituents may lead to strong symmetry breaking and to a modified electronic structure. The spectroscopic properties of a series of four bis-TAA donor-bridge-donor X-B-X dimers, composed of two asymmetric TAA chromophores (monomers) were investigated. UV/vis-, fluorescence and transient absorption spectra were recorded and compared with those of the corresponding X-B monomers. The excited states of the dimers are described as MV states which show, depending on the chemical nature of the bridge, a varying amount of interactions. It was found that superradiant emission only proceeds in the case of weak and medium coupling. Whether the first excited state potential energy surface of the dimers is a single minimum or a double minimum potential depends on the solvent polarity and the electronic coupling. In the latter case, the dimer relaxes in a symmetry broken CT state. The [2.2]paracyclophane bridged dimer is an example for a weakly coupled system, because the spectroscopic behavior is very similar to the corresponding p xylene monomer. In contrast, anthracene as well as p-xylene bridges mediate a stronger coupling and reveal a significant cooperative influence on the optical properties. A series of …
abstract: The one electron oxidation potential of ten TAAs with all permutations of Cl , OMe- and Me-substituents in the three p-positions were determined by CV. The half wave potential of the first oxidation wave correlates linearly with the number of Cl- and OMe-substituents. AM1-CISD derived values of the absorption energies are in good agreement with the experiments but differ strongly for the oscillator strengths as well as for neutral compounds and their corresponding mono radical cations. The small solvent dependence of the experimental UV/Vis spectra in CH2Cl2 and MeCN reflects a minor charge transfer character of the electronic transitions. The UV/Vis/NIR spectra of the series of TAAs and their corresponding radical cations and the AM1 computations reveal that even small substituents may lead to strong symmetry breaking and to a modified electronic structure. The spectroscopic properties of a series of four bis-TAA donor-bridge-donor X-B-X dimers, composed of two asymmetric TAA chromophores (monomers) were investigated. UV/vis-, fluorescence and transient absorption spectra were recorded and compared with those of the corresponding X-B monomers. The excited states of the dimers are described as MV states which show, depending on the chemical nature of the bridge, a varying amount of interactions. It was found that superradiant emission only proceeds in the case of weak and medium coupling. Whether the first excited state potential energy surface of the dimers is a single minimum or a double minimum potential depends on the solvent polarity and the electronic coupling. In the latter case, the dimer relaxes in a symmetry broken CT state. The [2.2]paracyclophane bridged dimer is an example for a weakly coupled system, because the spectroscopic behavior is very similar to the corresponding p xylene monomer. In contrast, anthracene as well as p-xylene bridges mediate a stronger coupling and reveal a significant cooperative influence on the optical properties. A series of …
author: Amthor, Stephan
keywords: Triarylamin, Cyclophan, Mulliken-Hush, Intervalenzladungstransfer, Komplexierung, triaryalmine, cyclophane, intervalence charge-transfer, complexation
date published: 2005-12-12
date modified: 2026-07-24T06:11:45Z
provider: Universität Wüzburg
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Universität Würzburg