Charge Transport and Conductance Switching of Redox‐Active Azulene Derivatives

Schwarz, Florian; Koch, Michael; Kastlunger, Georg; Berke, Heinz; Stadler, Robert; Venkatesan, Koushik; Lörtscher, Emanuel

doi:10.1002/anie.201605559

Cited by 79 publications

(81 citation statements)

References 26 publications

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“…The lower HOMO and LUMO energy levels of rDPhPz are mainly due to the lower electron‐donating ability of carbazole and the larger conjugated plane resulted from fusion of carbazole and azasiline. DFT calculations well predict all these experimental changing trends and the calculated isosurfaces of HOMO, LUMO, and electrostatic potential (ESP) delocalize on the whole molecular architectures, confirming the high extension of π‐conjugation in these all‐aryl phenazasilines …”

Section: Methodssupporting

confidence: 54%

High‐Performance All‐Aryl Phenazasilines via Metal‐Free Radical‐Mediated CH Silylation for Organic Light‐Emitting Diodes

Shen

Chen

et al. 2018

Advanced Optical Materials

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complicated synthetic routes to prepare heteroatom-containing materials with specifically introduced heteroatoms on the desired positions of an aromatic molecule, and it becomes even more challenging, when multiple and/or multitype heteroatoms are designed to be introduced. [5][6][7] Phenazasilines, which contain both Si and N heteroatoms in a fused six-membered ring, are typical examples. [8,9] Structurally similar to the popular donor moiety of 9,10-dihydroacridine by replacing its 9-C with Si, [10] phenazasilines can benefit from both 9,10-dihydroacridine-alike architecture and Si incorporation, exhibiting intrinsically promising properties as hole-transporting materials for organic field effect transistors [11] with a hole mobility of 10 −4 cm 2 V −1 s −1 and an ON-OFF ratio close to 10 5 , thermally activated delayed fluorescence (TADF) emitters [12] for organic light emitting diodes (OLEDs) with external quantum efficiency (EQE) up to 22.3%, and host materials [13] for phosphorescent OLEDs (PhOLEDs) with EQE of 12%. Nevertheless, the synthesis of phenazasilines, either traditionally through extended heating of diphenylsilane with phenothiazines [14] and cyclization reaction between 2,2′-dilithiodiarylamine intermediates and dichlorosilanes, [15] or recently by rhodium-catalyzed double activation of SiH and CH bonds for dehydrogenation and SiC coupling, [13] suffers from the low yields, complicated precursors, long synthetic routes, or high chemical costs. These synthetic difficulties significantly hinder the investigations and applications of phenazasilines, although they have already shown promising optical and electronic properties for high-performance device applications due to the combined effects of Si and N heteroatom incorporation.With planar π-conjugated molecular structure, phenazasilines are especially attractive for OLEDs to function as emitters, charge transporters, and host materials. However, due to the planar molecular geometry of phenazasilines with a phenyl-fused azasiline ring, strong π-π stacking and heavy intermolecular interaction are generally observed, especially in the solid state, leading to broad and redshifted excimer emission and coarse film morphology. [16,17] To alleviate the intermolecular interactions, bulky phenyl substituents on the Heteroatom-containing organic molecules show a unique combination of properties for high-performance optoelectronic applications. With both Si and N heteroatoms in an aromatic architecture, phenazasilines are promising for optoelectronic devices, except for their synthetic difficulties. Through a newly developed two-step SiH/CH coupling silylation in a metal-free intramolecular radical-mediated catalysis mechanism, all-aryl phenazasilines that can be hardly synthesized by previous methods are facilely prepared and found to have excellent optoelectronic properties with both high thermal stability and high solubility due to the effects of bulky diphenyl substituents on Si, which cannot only strengthen the intramolecular interactions but also ...

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Section: Methodssupporting

confidence: 54%

High‐Performance All‐Aryl Phenazasilines via Metal‐Free Radical‐Mediated CH Silylation for Organic Light‐Emitting Diodes

Shen

Chen

et al. 2018

Advanced Optical Materials

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“… 1 – 4 Recently, quantum interference effects due to different electron pathways through molecular systems with varied connectivities have been intensively explored via single-molecule conductance studies of benzene, 5 oligo(phenylene ethynylene), 6 anthraquinone, 7 unsaturated carbon chains, 8 and azulene. 9 , 10 Destructive quantum interference brings anti-resonances within their HOMO–LUMO gaps, which significantly reduces their single-molecule conductance and leads to new control strategies for molecular-scale devices.…”

Section: Introductionmentioning

confidence: 99%

Protonation tuning of quantum interference in azulene-type single-molecule junctions

et al. 2017

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“…70 In a more recent study a range of bis(acetylthio) functionalized azulenes such as 121 and 122 were prepared and studied as single molecule junctions. 71 In both cases palladium-catalyzed Sonogashira coupling using 4-(acetylthio)phenylacetylene and the appropriate aryl halides gives the products in excellent yield.…”

Section: Di(arylalkynyl)biaryls and Azulenesmentioning

confidence: 99%