Carbon-Bridged Oligo(phenylenevinylene)s: Stable π-Systems with High Responsiveness to Doping and Excitation
摘要:
The high responsiveness of pi-conjugated materials to external stimuli, such as electrons and photons, accounts for both their utility in optoelectronic applications and their chemical instability. Extensive studies on heteroatom-stabilized pi-conjugated systems notwithstanding, it is still difficult to combine high performance and stability. We report here that carbon-bridged oligo(p-phenylenevinylene)s (COPV-n) are not only more responsive to doping and photoexcitation but also more stable than the conventional p-phenylenevinylenes and poly(3-hexylthiophene), surviving photolysis very well in air, suggesting that they could serve as building blocks for optoelectronic applications. Activation of the ground state by installation of bond angle strain toward the doped or photoexcited state and the flat, rigid, and hindered structure endows COPVs with stimuli-responsiveness and stability without recourse to heteroatoms. For example, COPV-6 can be doped with an extremely small reorganization energy and form a bipolaron delocalized over the entire it system. Applications to bulk and molecular optoelectronic devices are foreseen.
Air- and Heat-Stable Planar Tri-p-quinodimethane with Distinct Biradical Characteristics
摘要:
A heptacyclic carbocycle possessing three p-quinodimethane units conjugated in one plane has been synthesized and shown to exhibit distinct biradical characteristics. The molecule has a HOMO/LUMO band gap of ca. 1 eV and a S(0)-T(1) energy gap of 2.12 kcal/mol, and it absorbs and emits near-IR light at room temperature. It is air-stable under ambient light for several months and thermally stable up to 160 degrees C under nitrogen, and it undergoes reversible two-electron oxidation and reduction. The synthetic approach is such that a smaller and larger oligo-p-quinodimethane can be synthesized.
Linearly conjugated systems have long served as an archetype of conjugated materials, but suffer from two intrinsic structural problems: potential instability due to intermolecular interactions and the flexibility of the C-C bonds connecting C═C bonds. Efforts to solve these problems have included the insertion of aromatic units as a part of the conjugation and the introduction of carbon bridges to
Stabilization of the radical cationic state of a donor molecule by 3-D homoconjugation was probed using a substituted carbon-bridged oligophenylenevinylene backbone (COPV, or 5,5-diarylindeno[2,1-a]indenes). For molecules bearing electron-donating groups as the 5,5-aryl moieties, a one-electron oxidation of the COPV backbone results in delocalization of the cationic charge over the whole molecule with
Bis(aminoaryl) Carbon-Bridged Oligo(phenylenevinylene)s Expand the Limits of Electronic Couplings
作者:Paula Mayorga Burrezo、Nai-Ti Lin、Koji Nakabayashi、Shin-ichi Ohkoshi、Eva M. Calzado、Pedro G. Boj、María A. Díaz García、Carlos Franco、Concepciò Rovira、Jaume Veciana、Michael Moos、Christoph Lambert、Juan T. López Navarrete、Hayato Tsuji、Eiichi Nakamura、Juan Casado
DOI:10.1002/anie.201610921
日期:2017.3.6
Carbon‐bridged bis(aminoaryl) oligo(para‐phenylenevinylene)s have been prepared and their optical, electrochemical, and structural properties analyzed. Their radical cations are class III and class II mixed‐valence systems, depending on the molecular size, and they show electronic couplings which are among the largest for the self‐exchange reaction of purely organic molecules. In their dication states
Muraoka,M. et al., Chemical and pharmaceutical bulletin, 1960, vol. 8, p. 860 - 866
作者:Muraoka,M. et al.
DOI:——
日期:——
Synthesis of alkyl- and alkoxy-substituted benzils and oxidative coupling to tetraalkoxyphenanthrene-9,10-diones
作者:Bernhard Mohr、Volker Enkelmann、Gerhard Wegner
DOI:10.1021/jo00082a022
日期:1994.2
Intermolecular Friedel-Crafts acylation of various substituted alkyl- or alkoxybenzenes with oxalyl chloride using carbon disulfide as solvent gave rise to the benzils 1a-k. Subsequent intramolecular oxidative coupling with either thallium(III) oxide/trifluoroacetic acid or vanadium(V) oxyfluoride/boron trifluoride diethyl etherate resulted in the corresponding phenanthrene-9,10-diones 2a-d. It has been shown that oxygen functionalities at the 3, 3', 4, and 4' positions are necessary for coupling to occur. These substituted benzils and phenanthrene-9,10-diones constitute precursors for ligands in the field of discotic metallomesogens or polymeric mesogens.