Organic high-spin and mixed-valence systems; synthesis, electrochemical and spectroscopic studies of asymmetric and symmetric tetraaryl- m -phenylenediamines

Yano, Masafumi; Aoyama, Kentaro; Ishida, Yutaka; Tatsumi, Masakazu; Sato, Kazunobu; Shiomi, Daisuke; Takui, Takeji

doi:10.1016/s0277-5387(03)00304-8

Cited by 6 publications

(5 citation statements)

References 14 publications

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“…The radical cation of bis(triarylamine) 111 (Chart ) is essentially a topological isomer of 35 + with two additional methyl groups at the bridging benzene unit. In the para-substituted phenylenediamine 35 , the first two one-electron oxidations are 410 mV apart, but in the meta-substituted compound 111 the difference is only 160 mV . In the latter, the two redox units are in fact so effectively decoupled from one another that the biradical form ( 111 2+ ) becomes stable in solution at −78 °C.…”

Section: Electronic Coupling In Covalent Systems: Importance Of the M...mentioning

confidence: 99%

Organic Mixed Valence

2011

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Section: Electronic Coupling In Covalent Systems: Importance Of the M...mentioning

confidence: 99%

Organic Mixed Valence

2011

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“…Triarylamine moieties have recently been used as redox centers in a number of mixed-valence (MV) compounds − and redox cascades in order to study hole transfer processes. MV species are generally characterized by at least two redox centers with unequal formal oxidation states.…”

Section: Introductionmentioning

confidence: 99%

[2.2]Paracyclophane-Bridged Mixed-Valence Compounds: Application of a Generalized Mulliken−Hush Three-Level Model

2005

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A series of [2.2]paracylophane-bridged bis-triarylamine mixed-valence (MV) radical cations were analyzed by a generalized Mulliken-Hush (GMH) three-level model which takes two transitions into account: the intervalence charge transfer (IV-CT) band which is assigned to an optically induced hole transfer (HT) from one triarylamine unit to the second one and a second band associated with a triarylamine radical cation to bridge (in particular, the [2.2]paracyclophane bridge) hole transfer. From the GMH analysis, we conclude that the [2.2]paracyclophane moiety is not the limiting factor which governs the intramolecular charge transfer. AM1-CISD calculations reveal that both through-bond as well as through-space interactions of the [2.2]paracyclophane bridge play an important role for hole transfer processes. These electronic interactions are of course smaller than direct pi-conjugation, but from the order of magnitude of the couplings of the [2.2]paracyclophane MV species, we assume that this bridge is able to mediate significant through-space and through-bond interactions and that the cyclophane bridge acts more like an unsaturated spacer rather than a saturated one. From the exponential dependence of the electronic coupling V between the two triarylamine localized states on the distance r between the two redox centers, we infer that the hole transfer occurs via a superexchange mechanism. Our analysis reveals that even significantly longer pi-conjugated bridges should still mediate significant electronic interactions because the decay constant beta of a series of pi-conjugated MV species is small.

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“…The understanding of the physical and chemical properties of triarylamines and their oxidized counterparts are of fundamental interest because they were widely used as hole conducting materials in organic light emitting devices, − polymer batteries, , photorefractive materials for optical data storage, and in electrochromic polymers, e.g., for anti-glare electrochromic mirrors as well as in the Xerox process ,,, of laser printers and photocopiers. Bis-triarylamines with two nitrogen N redox centers that are connected by varying bridging units B are well known, and the corresponding monocationic mixed valence (MV) species [N−B−N] + are of great importance for studying hole transfer (HT) processes from one redox center to the other redox center. − A profound influence of the bridge on the HT properties has been demonstrated for several examples. ,,,,, In addition to the triarylamine to triarylamine HT in MV species, it has been shown that for some systems an additional HT to the bridge B has to be taken into account for a more detailed description of the MV system. , In this context, bridge-localized MV species with excited-state mixed-valence character were described and analyzed. ,, A dihydrazine diradical dication with excited MV states was described by a similar model…”

Section: Introductionmentioning

confidence: 99%

Dications of Bis-triarylamino-[2.2]paracyclophanes: Evaluation of Excited State Couplings by GMH Analysis

Amthor

Lambert

2006

J. Phys. Chem. A

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In this paper, we present the absorption properties of a series of bis-triarylamino-[2.2]paracyclophane diradical dications. The localized pi-pi and the charge-transfer (CT) transitions of these dications are explained and analyzed by an exciton coupling model that also considers the photophysical properties of the "monomeric" triarylamine radical cations. Together with AM1-CISD-calculated transition moments, experimental transition moments and transition energies of the bis-triarylamine dications were used to calculate electronic couplings by a generalized Mulliken-Hush (GMH) approach. These couplings are a measure for interactions of the excited mixed-valence CT states. The modification of the diabatic states reveals similarities of the GMH three-level model and the exciton coupling model. Comparison of the two models shows that the transition moment between the excited mixed-valence states mu(ab) of the dimer equals the dipole moment difference Delta of the ground and the excited bridge state of the corresponding monomer.

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Organic high-spin and mixed-valence systems; synthesis, electrochemical and spectroscopic studies of asymmetric and symmetric tetraaryl- m -phenylenediamines

Cited by 6 publications

References 14 publications

Organic Mixed Valence

Organic Mixed Valence

[2.2]Paracyclophane-Bridged Mixed-Valence Compounds: Application of a Generalized Mulliken−Hush Three-Level Model

Dications of Bis-triarylamino-[2.2]paracyclophanes: Evaluation of Excited State Couplings by GMH Analysis

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