Synthesis of Nonaphenylenes and Dodecaphenylenes Using Electron-transfer Oxidation of Lipshutz Cuprate Intermediates

Iyoda, Masahiko; Rahman, Mohammad A.; Matsumoto, Aoi; Wu, Mo; Kuwatani, Yoshiyuki; Nakao, Kazumi; Miyake, Yoshihiro

doi:10.1246/cl.2005.1474

Cited by 16 publications

(3 citation statements)

References 19 publications

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“…The latter reaction was conducted in CDCl 3 to enable monitoring of the reaction by 1 H NMR, as the tris -bromide 3a is not separable from the corresponding mono- and dibrominated compounds. The 3-fold reductive dimerization of tris -bromide 3a to form the benzene-capped cage 4a via the Lipshutz cuprate, [Ar 2 Cu(CN)Li 2 ] (as described by Iyoda), − and related methods involving direct 3-fold lithiation of the thiophene C–H bond adjacent to sulfur followed by CuCl 2 or FeCl 3 -mediated dimerization, , were complicated by the formation of inseparable impurities. In contrast, 3-fold nickel(0)-mediated reductive dimerization − delivered the benzene-capped cage 4a in 37% yield.…”

Section: Resultsmentioning

confidence: 99%

Chemical Tuning of Exciton versus Charge-Transfer Excited States in Conformationally Restricted Arylene Cages

et al. 2021

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Covalent assemblies of conjugated organic chromophores provide the opportunity to engineer new excited states with novel properties. In this work, a newly developed triple-stranded cage architecture, in which meta-substituted aromatic caps serve as covalent linking groups that attach to both top and bottom of the conjugated molecule walls, is used to tune the properties of thiophene oligomer assemblies. Benzene-capped and triazine-capped 5,5′-(2,2-bithiophene)-containing arylene cages are synthesized and characterized using steady-state and time-resolved spectroscopic methods. The conformational freedom and electronic states are analyzed using time-dependent density functional theory. The benzene cap acts as a passive spacer whose electronic states do not mix with those of the chromophore walls. The excited state properties are dominated by through-space interactions between the chromophore subunits, generating a neutral Frenkel H-type exciton state. This excitonic state undergoes intersystem crossing on a 200 ps time scale while the fluorescence output is suppressed by a factor of 2 due to a decreased radiative rate. Switching to a triazine cap enables electron transfer from the chromophore-linker after the initial excitation to the exciton state, leading to the formation of a charge-transfer state within 10 ps. This state can avoid intersystem crossing and exhibits red-shifted fluorescence with enhanced quantum yield. The ability to interchange structural modules with different electronic properties while retaining the overall cage morphology provides a new approach for tuning the properties of discrete chromophore assemblies.

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Section: Resultsmentioning

confidence: 99%

Chemical Tuning of Exciton versus Charge-Transfer Excited States in Conformationally Restricted Arylene Cages

et al. 2021

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“…Herein, we report the results of our investigations on the synthesis of nonaphenylenes and dodecaphenylenes using electron-transfer oxidation of Lipshutz cuprates and their unique properties. Although the synthesis of 1a , 1b , 1c , and 2b , together with the X-ray structure of 1b has already been reported as a preliminary form, we summarize the results of the oligophenylene synthesis and show further research on the formation of nanostructures from oligophenylenes.…”

Section: Introductionmentioning

confidence: 90%

Synthesis of Nonaphenylenes and Dodecaphenylenes Using Electron-Transfer Oxidation of Lipshutz Cuprates and Formation of Nanostructural Materials from Hexadodecyloxynonaphenylene

et al. 2008

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Nonaphenylenes and dodecaphenylenes have been synthesized by using electron-transfer oxidation of Lipshutz cuprates with duroquinone. Oxidation of the Lipshutz cuprate derived from 4,4''-dibromo-o-terphenyl 3a in THF produced nonaphenylene 1a in 46% yield, whereas the similar oxidation of the Lipshutz cuprates derived from 4,4''-diiodo-4',5'-dialkyl-o-terphenyls 3b-d in ether afforded the corresponding nonaphenylenes 1b-d and dodecaphenylenes 2b-d in moderate total yields. In the case of 4,4''-diiodo-4',5'-didodecyloxy-o-terphenyl 3e as the starting material, oxidation of the corresponding Lipshutz cuprate in ether or THF only led to the formation of nonaphenylene 1e. Both nonaphenylenes 1a-e and dodecaphenylenes 2b-d are unreactive to light, atmospheric oxygen, and prolonged heating. These oligophenylenes showed strong UV absorption and fluorescent emission and exhibited some redox properties on CV analysis. Moreover, hexadodecyloxynonaphenylene 1e exhibits different nanostructures on the surface and in solution to form a film by casting a solution of 1e in cyclohexane, benzene, chloroform, THF, or diisopropyl ether (IPE) and nanofibers from IPE-MeOH (1:1), indicating different absorption and emission spectra and XRD patterns. The absorption maxima of THF solution, fiber, and film are in the order of 1e film (315 nm) > fiber (302 nm) > solution (295 nm), whereas the emission maxima are in the order of 1e fiber (425 m) > solution (418 nm) > film (401 nm). XRD analysis revealed that 1e aligns laterally on a glass or silicon surface to form a thin film with a lamella structure; however, it forms a nanofiber with a Lego-like stacking structure without pi-pi stacking interaction of the aromatic rings. Reflecting the different nanostructures of the 1e film and fiber, a spin-coated 1e film is found to be effective in detecting the vapor of explosives due to the intercalation of nitroaromatics to the cracked surface of the loosely stacked 1e. In contrast, the 1e fiber is not effective in detection of nitroaromatics but exhibits fluorescence anisotropy. The maximum fluorescence intensity is obtained in a direction perpendicular to the longitudinal axis of the fiber, indicating the stacking direction to be parallel to the longitudinal axis of the fiber.

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“…[41] The ET oxidation of the corresponding Lipshutz cuprate, however, resulted in 46 a being obtained in 46 % yield. [42] Furthermore, hexaalkylnonaphenylenes 46 b-d and hexadodecyloxynonaphenylene 46 e were synthesized in moderate yields with small amounts of octaalkyldodecaphenylenes 47 b-d. Since only small amounts of linear oligomeric by-products are produced by the ET oxidation of Lipshutz cuprates, the isolation of 46 ae and 47 b-d is rather simple.…”

Section: Cyclic Oligophenylenesmentioning

confidence: 99%

Conjugated Macrocycles: Concepts and Applications

2011

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One of the most important objectives in materials, chemical, and physical sciences is the creation of large conjugated macrocycles with well-defined shapes, since such molecules are not only theoretically and experimentally interesting but also have potential applications in nanotechnology. Fully unsaturated macrocycles are regarded as models for infinitely conjugated π systems with inner cavities, and exhibit unusual optical and magnetic behavior. Macrocycles have interior and exterior sites, and site-specific substitution at both or either site can afford attractive structures, such as 1D, 2D, and 3D supramolecular nanostructures. These nanostructures could be controlled through the use of π-extended large macrocycles by a bottom-up strategy. Numerous shape-persistent π-conjugated macrocycles have been synthesized, but only a few are on the nanoscale. This Review focuses on nanosized π-conjugated macrocycles (>1 nm diameter) and giant macrocycles (>2 nm diameter), and summarizes their syntheses and properties.

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Synthesis of Nonaphenylenes and Dodecaphenylenes Using Electron-transfer Oxidation of Lipshutz Cuprate Intermediates

Cited by 16 publications

References 19 publications

Chemical Tuning of Exciton versus Charge-Transfer Excited States in Conformationally Restricted Arylene Cages

Chemical Tuning of Exciton versus Charge-Transfer Excited States in Conformationally Restricted Arylene Cages

Synthesis of Nonaphenylenes and Dodecaphenylenes Using Electron-Transfer Oxidation of Lipshutz Cuprates and Formation of Nanostructural Materials from Hexadodecyloxynonaphenylene

Conjugated Macrocycles: Concepts and Applications

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