Layered Electron Acceptors by Dimerization of Acenes End‐ Capped with 1,2,5‐Thiadiazoles

Novel synthetic methodologies allow increasingly efficient access to known organic materials, as well as the preparation of otherwise inaccessible species. Pd-catalyzed coupling of aromatic dihalides to ortho-diaminoarenes furnishes embedded stable N,N'-dihydropyrazines expediently and in often excellent yields. The embedded N,N'-dihydropyrazines can then be oxidized by MnO2 to give substituted azatetracenes, azapentacenes, azahexacenes, and azaheptacenes, which are soluble, processable, and stable. This powerful Pd-catalyzed methodology allows the preparation of azaacenes, including diaza-, tetraaza- and hexaazaacenes. In combination with a suitable Pd precursor, Buchwald-type biarylphosphines have been shown to give excellent results. Activated dihalides such as 2,3-dihaloquinoxalines are coupled easily under simplified conditions, whereas 2,3-dibromoacenes require more stringent conditions and advanced catalyst precursors. Pd catalysts effect the assembly of azaacenes with otherwise difficult to obtain substitution patterns. High yields and flexibility make this method most attractive.

Section: Scheme11 Synthesis Of Diazapentacenes From Unactivated Dihamentioning

confidence: 99%

The Palladium Way to N‐Heteroacenes

Bunz

Engelhart

2016

“…Herein we investigate 2,1,3‐benzothiadiazoles for the nature of their sulfur interactions, the factors controlling CB geometry, and how these forces compete with other crystal packing forces . 2,1,3‐Benzothiadiazole ( 1 b ; Figure a) and its derivatives serve as an effective test‐case because of their affinity for crystallization, relevance to medicinal chemistry and materials science . Furthermore, many structural derivatives are capable of forming 2S–2N square dimeric or polymeric interactions within their crystalline lattices (Figures b,c), and the scaffold allows for the systematic substitution of positions 4–7 on the benzo ring.…”

Section: Introductionmentioning

confidence: 99%

Chalcogen Bonding “2S–2N Squares” versus Competing Interactions: Exploring the Recognition Properties of Sulfur

Mark

Trapp

Schwab

et al. 2018

Chalcogen bonding (CB) is the focus of increased attention for its applications in medicinal chemistry, materials science, and crystal engineering. However, the origin of sulfur's recognition properties remains controversial, and experimental evidence for supporting theories is still emerging. Here, a comprehensive evaluation of sulfur CB interactions is presented by investigating 2,1,3‐benzothiadiazole X‐ray crystallographic structures gathered from the Cambridge Structure Database (CSD), Protein Data Bank (PDB), and own laboratory findings. Through the systematic analysis of substituent effects on a subset library of over thirty benzothiadiazole derivatives, the competing interactions have been categorized into four main classes, namely 2S–2N CB square, halogen bonding (XB), S⋅⋅⋅S, and hydrogen‐bonding (HB). A geometric model is employed to characterize the 2S–2N CB square motifs and discuss the role of electrostatic, dipole, and orbital contributions toward the interaction.

“…Acenes have made a significant impact on organic functional materials due to their unique optical and electrical properties, especially as activated layers in organic field effect transistors (OFETs), organic light‐emitting diodes (OLEDs), and organic photovoltaics (OPVs) . In recent years, synthetic chemists have devoted substantial efforts to studying linear azaacenes . However, with the molecular length increasing, its stability diminishes, and even decomposes .…”

Section: Introductionmentioning

confidence: 99%

Sulfur‐Containing Bent N‐Heteroacenes

Ding

Xia

Sun

et al. 2019

Self Cite

A series of novel sulfur‐containing bent N‐heteroacenes were constructed and characterized by NMR and UV/Vis spectroscopy, cyclic voltammetry, and single‐crystal X‐ray diffraction. By introducing sulfur‐containing groups (thio, sulfinyl, and sulfonyl) into bent azaacenes, their electronic delocalization was improved and frontier energy levels were modulated. The target products displayed tunable optical and electronic properties through altering the valence of sulfur and fused length of the azaacenes. For the first time, typical products were utilized as organic field effect transistor materials, affording promising results.