Catalytic Synthesis of Conjugated Azopolymers from Aromatic Diazides

Andjaba, John M.; Rybak, Christopher J.; Wang, Zhiyang; Ling, Jianheng; Mei, Jianguo; Uyeda, Christopher

doi:10.1021/jacs.1c00447

Cited by 24 publications

(23 citation statements)

References 65 publications

(33 reference statements)

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“…As far as the synthetic method is concerned, MCPABs can be prepared by either prefunctionalization , (polycondensation on azo-monomers) or in situ functionalization (azo bond formation polymerizations) strategy. The former one represented the major methods (Scheme a), including polyesterification, Michael addition polymerization, Suzuki–Miyaura coupling, click chemistry, and other coupling reactions .…”

mentioning

confidence: 99%

Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes

Younis

Long

Peng

et al. 2021

J. Phys. Chem. Lett.

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Although side-chain polyazobenzenes have been extensively studied, main-chain polyazobenzenes (abbreviated MCPABs) are rarely reported due to the challenges associated with difficulty in synthetic chemistry and photoisomerization of azo bonds in MCPABs. Thus, it is highly demanded to develop new mechanisms other than photoisomerization of azo bonds in MCPABs to extend their applications. In this work, we created a new series of N-linked MCPABs via fast NaBH 4 -mediated reductive coupling polymerization on N-substituted bis(4-nitrophenyl)amines. The structure of MCPABs has been characterized by comprehensive solid-state NMR experiments such as CPMAS 13 C NMR with long and short contact times, cross-polarization polarization-inversion (CPPI), and cross-polarization nonquaternary suppressed (CPNQS). The azo bonds in MCPABs were found to be promising for acid vapor sensing, being acidified to form azonium ion with significant color change from red to green. And the azonium of MCPABs turned from green to red when exposed to base vapor, thus suitable for base vapor sensing.

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confidence: 99%

Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes

Younis

Long

Peng

et al. 2021

J. Phys. Chem. Lett.

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“…11 for selected examples) and enabled efficient reactivity with diazides to form azopolymers. 55 As indicated above, only few complexes were able to produce azoarenes catalytically via nitrene homocoupling. With the notable exception of the Ueyda's system, most of these catalysts exhibited limited substrate scope, typically operating on phenyl azide or selected electron-rich azides.…”

Section: Perspectivementioning

confidence: 96%

Catalytic synthesis of azoarenes via metal-mediated nitrene coupling

Groysman

Kurup

2022

Dalton Trans.

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“…Catalytic dimerizations of >20 aryl azides were carried out using 1–10 mol% of Ni 2 catalyst 1 . By using aromatic diazides as substrates, we were also able to develop catalytic polymerization reactions that generate conjugated materials linked through NN bonds . Ongoing studies are aimed at studying the photochemical and electrochemical properties of these polymers.…”

Section: Stoichiometric Reactivity and Catalysismentioning

confidence: 99%

Dinickel Active Sites Supported by Redox-Active Ligands

Uyeda

Farley

2021

Acc. Chem. Res.

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Conspectus Redox reactions that take place in enzymes and on the surfaces of heterogeneous catalysts often require active sites that contain multiple metals. By contrast, there are very few homogeneous catalysts with multinuclear active sites, and the field of organometallic chemistry continues to be dominated by the study of single metal systems. Multinuclear catalysts have the potential to display unique properties owing to their ability to cooperatively engage substrates. Furthermore, direct metal-to-metal covalent bonding can give rise to new electronic configurations that dramatically impact substrate binding and reactivity. In order to effectively capitalize on these features, it is necessary to consider strategies to avoid the dissociation of fragile metal–metal bonds in the course of a catalytic cycle. This Account describes one approach to accomplishing this goal using binucleating redox-active ligands. In 2006, Chirik showed that pyridine–diimines (PDI) have sufficiently low-lying π* levels that they can be redox-noninnocent in low-valent iron complexes. Extending this concept, we investigated a series of dinickel complexes supported by naphthyridine–diimine (NDI) ligands. These complexes can promote a broad range of two-electron redox processes in which the NDI ligand manages electron equivalents while the metals remain in a Ni(I)–Ni(I) state. Using (NDI)Ni2 catalysts, we have uncovered cases where having two metals in the active site addresses a problem in catalysis that had not been adequately solved using single-metal systems. For example, mononickel complexes are capable of stoichiometrically dimerizing aryl azides to form azoarenes but do not turn over due to strong product inhibition. By contrast, dinickel complexes are effective catalysts for this reaction and avoid this thermodynamic sink by binding to azoarenes in their higher-energy cis form. Dinickel complexes can also activate strong bonds through the cooperative action of both metals. Norbornadiene has a ring-strain energy that is similar to that of cyclopropane but is not prone to undergoing C–C oxidative addition with monometallic complexes. Using an (NDI)Ni2 complex, norbornadiene undergoes rapid ring opening by the oxidative addition of the vinyl and bridgehead carbons. An inspection of the resulting metallacycle reveals that it is stabilized through a network of secondary Ni−π interactions. This reactivity enabled the development of a catalytic carbonylative rearrangement to form fused bicyclic dienones. These vignettes and others described in this Account highlight some of the implications of metal–metal bonding in promoting a challenging step in a catalytic cycle or adjusting the thermodynamic landscape of key intermediates. Given that our studies have focused nearly exclusively on the (NDI)Ni2 system, we anticipate that many more such cases are left to be discovered as other transition-metal combinations and ligand classes are explored.

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Catalytic Synthesis of Conjugated Azopolymers from Aromatic Diazides

Cited by 24 publications

References 65 publications

Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes

Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes

Catalytic synthesis of azoarenes via metal-mediated nitrene coupling

Dinickel Active Sites Supported by Redox-Active Ligands

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