Synthesis and Tunability of Highly Electron-Accepting, N-Benzylated “Phosphaviologens”

New P/N-containing π-electron systems comprising fully planar biaryl arrays are synthesized by multiple radical phosphanylation. The biaryl moiety in these highly strained planar π-systems is rigidified by double P-bridging. The electronic properties of the core biaryl entity are varied by introducing N-donor substituents or by installing N-atoms within the π-system, thereby moving to the viologen core structure. The electrochemical and photophysical properties of these compounds are discussed and compared with those of related systems.

Section: Methodssupporting

confidence: 91%

“…Considering the reversible redox properties of viologens passing through differently colored intermediates, and encouraged by recent studies, we attempted the selective monoreduction of trans ‐ 7 via SET to access the corresponding intermediate, deep‐blue colored radical cation trans ‐ 7 . + .…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Physical Properties of Strained Doubly Phosphorus‐Bridged Biaryls and Viologens

Greulich

Yamaguchi

Doerenkamp

et al. 2017

“…The successful results of the first phosphaviologen species lead to further research, exploring the electronic differences while utilizing various substituents, as well applications to organic electronics. An N , N′ ‐dibenzylated phosphaviologen (BMV; Figure a) was investigated for its electronic properties, and applied in an electrochromic device . CV confirmed complete reversibility for both redox events (Figure b), and surprisingly lower reductions (Table ) than the previously reported dimethylated phosphaviologen.…”

Section: Modified Viologensmentioning

confidence: 75%

Viologens and Their Application as Functional Materials

Striepe

Baumgartner

2017

Self Cite

268

235

Organic materials have recently gained considerable attention for electronic applications, improving performance and sustainability to current technologies. Commercialized metal-based systems are generally expensive, toxic and difficult to recycle, however organic materials offer promising solutions. Viologens, N,N' di-quaternized bipyridyl salts, are a well-studied species exhibiting three reversible redox states, possessing valuable electrochromic and electron-accepting properties. These properties can be fine-tuned through synthesis by altering the nitrogen substituents and various counteranions. Currently, viologens have become of great interest as functional materials in a wide array of applications; a few to name include electrochromic devices, molecular machines, and organic batteries. This review highlights representative recent work and advances towards utilizing viologens in practical applications that currently compete with metal-based technologies. Additionally, modified viologens that can be further fine-tuned will be discussed.

“…Moreover, shedding light on the high synthetic versatility of λ 3 ‐σ 3 phosphorus centers of phospholes triggered an extensive development of organophosphorus materials; λ 3 ‐σ 3 phosphorus centers possess a variety of selective post‐functionalization reactions that provide unique means to tailor the materials’ optoelectronic properties for practical applications. As a result, organophosphorus materials containing five‐membered phosphorus heterocycles have led to important breakthroughs in fields such as liquid crystals, OLEDs, solar cells, electrochromic materials, and sensors, just to name a few.…”

Section: Introductionmentioning

confidence: 99%

A Guide for the Design of Functional Polyaromatic Organophosphorus Materials

Hindenberg

López‐Andarias

Röminger

et al. 2017

The impact of integrating six-membered phosphorus heterocycles into a poly(hetero)aromatic materials is investigated. Mechanistic studies reveal the key synthetic requirements to embed the latter phosphorus heterocycles in polyaromatic molecules. DFT calculations indicate that introducing six-membered phosphorus rings into π-extended molecules induces a particular electron distribution over the π-extended system. Electrochemical investigations confirm that inserting six-membered phosphacycles into polyaromatics triggers ambipolar redox behavior. Steady-state spectroscopy reveals that fusing pyrroles with phosphorus-containing polyaromatic molecules induces fluorescence quantum yields as high as 0.8, whereas transient absorption spectroscopy demonstrates that fusing thiophenes promote the formation of non-emissive triplet-excited states. As a whole, the optoelectronic properties of fused phosphorus-containing materials give rise to promising performances in photoelectrochemical cells. Moreover, X-ray analyses confirm that the 3D arrangement in the solid state of polyaromatic systems containing six-membered phosphorus rings can be tailored through post-functionalization of the phosphorus center. Altogether, this investigation sets the bedrock for the design of a new generation of highly functional polyaromatic organophosphorus materials, keeping control over their electrochemical properties, fluorescence features, photo-induced excited states, and 3D molecular arrangement.