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Hünig, Siegfried; Kemmer, Martina; Wenner, Hermann; Barbosa, Frédérique; Gescheidt, Georg; Perepichka, Igor F.; Bäuerle, Peter; Emge, Andreas; Peters, Karl

doi:10.1002/1521-3765(20000717)6:14<2618::aid-chem2618>3.3.co;2-n

Cited by 27 publications

(41 citation statements)

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“…This oxidative ring-closure is not restricted to entropically favorable transannular reactions (OX-8 2؉ , OX-16 2؉ , and OX-17 2؉ ), but also works with the formation of monocyclic rings (OX-13 2؉ , OX-22 2؉ , and OX-23 2؉ ) if a suitable ring size is achieved. In addition to electrochromic systems derived from the general structure of violene/cyanine hybrids, [12,18,19] type OL/CS [1] and type OS/CL represent another general structure in which the colored form consists of two closed-shell π-systems instead of the radical ions in classical organic electrochromic systems. [20] Electrochromic systems based on intramolecular ''no bond/single bond'' redox transformations according to Scheme 1 [21] offer further applications in ''molecular mechanics'', [22] due to the strong changes in geometry.…”

Section: Resultsmentioning

confidence: 99%

“…[12] Again, the longest wavelength absorption that could be attributable to Michler's hydrol type showed rather low intensity (cf. Scheme 3).…”

Section: Bis(azine) Red-8mentioning

confidence: 99%

“…Interestingly, as with OX-11 2؉ , [12] no nearly coplanar arrangement of the cationic ''Michler's hydrol blue moiety'' was found. One 4-(dimethylamino)phenyl group in these moieties seems to be lower in energy when twisted out of plane.…”

Section: Bis(azine) Red-8mentioning

confidence: 99%

“…Moreover, experimentally the two-electron oxidation of RED-8 resulted in a species with long-wavelength absorbance at around 600 nm, in good agreement with other, similar systems producing closed-shell systems with cyanine end groups on oxidation. [12,18,19] In contrast, when radical cation species are formed on oxidation in such a system the longest wavelength absorption is observed at substantially lower energies, in the near IR region. [12,19] RHF/AM1 calculations produced geometries (see Supporting Information) and energy differences between the three possible oxidation products similar to those calculated by RHF/PM3 (Table 2).…”

Section: Bis(azine) Red-8mentioning

confidence: 99%

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Electrochromics by Intramolecular Redox Switching of Single Bonds

et al. 2002

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Compounds of the general structure presented in Scheme 1 are proposed as electrochromic systems (ESs) in which reversible electron transfer is associated with breaking or forming of single bonds. In contrast to classical ESs, both redox states represent closed-shell systems. Whereas type OL/CS (Open form − Long-wavelength absorption/Closed form − Short-wavelength absorption) has already been demonstrated, this paper presents examples of the OS/CL type, in which the long-wavelength absorption is displayed by the ring-closed form. Bis(azines) RED-8, RED-13, RED-16, and RED-17, as well as the bis(amines) RED-22, RED-23, and RED-24 were prepared and characterized by their cyclic vol-

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Section: Resultsmentioning

confidence: 99%

“…[12] Again, the longest wavelength absorption that could be attributable to Michler's hydrol type showed rather low intensity (cf. Scheme 3).…”

Section: Bis(azine) Red-8mentioning

confidence: 99%

Section: Bis(azine) Red-8mentioning

confidence: 99%

Section: Bis(azine) Red-8mentioning

confidence: 99%

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Electrochromics by Intramolecular Redox Switching of Single Bonds

et al. 2002

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“…[2] It allows for reversible electron transfer due to its ªvioleneº type character, [4] but contains the moieties X-C-Y as end groups, which represent at least one ªcyanineº type structure in the fully reduced or oxidized form; this provides highly colored closed shell systems by an overall two-electron transfer.…”

Section: Introductionmentioning

confidence: 99%

Violene/Cyanine Hybrids as Electrochromics Part 2: Tetrakis(4-dimethylaminophenyl)ethene and Its Derivatives

et al. 2000

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The general structure of violene/cyanine hybrids (see below) is exemplified by tetrakis(4-dimethylaminophenyl)ethene 1(RED) its vinylogue 2(RED) and its diazavinylogue 3(RED). As judged from their cyclic voltammograms and spectroelectrograms, oxidation occurs perfectly reversible by loss of two electrons creating closed shell systems 1-3(OX)+2 with strong bathochromic shifts (Michlers hydrol blue moieties). ESR spectra indicate only minor amounts of radical cations. At much higher potentials by another reversible loss of two electrons (-->1-3(OX)+4) the long wavelengths absorptions are replaced by shorter ones. In system 4, containing two 4-dimethylaminophenyl units only, the violene character is better preserved since oxidation occurs stepwise by single electron transfer up to 4(OX)+4. These results are backed by theoretical calculations for 1-4, demonstrating the strong geometrical differences between the various oxidation levels. Besides, new types of cyclic structures for 1-4(OX)+4 are indicated by these calculations: For systems 1-3 cyclic structures for tetracations have been found to be more stable by 3-20 kcalmol(-1) than acyclic structures, whereas for system 4 the acyclic structure is more stable by about 22 kcalmol(-1). The redox behavior of systems 1-4 is of general importance for electrochromic systems.

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Hexaarylbutadiene: A Versatile Scaffold with Tunable Redox Properties towards Organic Near‐Infrared Electrochromic Material

Ishigaki

Harimoto

Sugimoto

et al. 2020

Chemistry An Asian Journal

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When the 1,1,4,4‐tetraanilinobutadiene skeleton is attached with two halogenated aryl units at the 2,3‐positions, they undergo facile two‐electron oxidation to give stable dicationic dyes which exhibit a near‐infrared (NIR) absorption whereas the neutral dienes show only pale color. Therefore, a distinct electrochromic response with an absorption change in the NIR region is achieved, which is attracting considerable recent attention from the viewpoint of bioimaging. Herein, we demonstrate that the redox potentials of the 1,1,4,4‐tetraanilinobutadiene can be precisely controlled by the donating properties of the amino group on the aniline unit as well as the number of halogen atoms on the aryl units at 2,3‐positions on the butadiene. In contrast, the NIR absorption bands mainly depend on the number of halogen atoms irrespective to the donating properties of aniline unit. Thus, the hexaarylbutadiene skeleton is proven to be a versatile scaffold to develop less‐explored organic NIR electrochromic materials, whose redox and spectroscopic properties can be finely tuned by modifying/attaching the proper substituents.

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Cited by 27 publications

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Electrochromics by Intramolecular Redox Switching of Single Bonds

Electrochromics by Intramolecular Redox Switching of Single Bonds

Violene/Cyanine Hybrids as Electrochromics Part 2: Tetrakis(4-dimethylaminophenyl)ethene and Its Derivatives

Hexaarylbutadiene: A Versatile Scaffold with Tunable Redox Properties towards Organic Near‐Infrared Electrochromic Material

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