Derivatization of 2,1,3-Benzothiadiazole via Regioselective C-H Functionalization and Aryne Reactivity.

Despite growing interest in 2,1,3-benzothiadiazole (BTD) as an integral component of many functional molecules, methods for the functionalization of its benzenoid ring have remained limited, and many even simply decorated BTDs have required de novo synthesis. We show that regioselective Ir-catalyzed C-H borylation allows access to versatile 5-boryl or 4,6-diboryl BTD building blocks, which undergo functionalization at the C4, C5, C6, and C7 positions. The optimization and regioselectivity of C-H borylation are discussed. A broad reaction scope is presented, encompassing ipso substitution at the C-B bond, the first examples of ortho-directed C-H functionalization of BTD, ring closing reactions to generate fused ring systems, as well as the generation and capture reactions of novel BTD-based heteroarynes. The regioselectivity of the latter is discussed with reference to the Aryne Distortion Model.

Flexible Ink-Jet Printed Polymer Light-Emitting Diodes using a Self-Hosted Non-Conjugated TADF Polymer.

Thermally activated delayed fluorescent (TADF) emitters have become the leading emissive materials for highly efficient organic light-emitting diodes (OLEDs). The deposition of these materials in scalable and cost-effective ways is paramount when looking toward the future of OLED applications. Herein, a simple OLED with fully solution-processed organic layers is introduced, where the TADF emissive layer is ink-jet printed. The TADF polymer has electron and hole conductive side chains, simplifying the fabrication process by removing the need for additional host materials. The OLED has a peak emission of 502 nm and a maximum luminance of close to 9600 cd m-2 . The self-hosted TADF polymer is also demonstrated in a flexible OLED, reaching a maximum luminance of over 2000 cd m-2 . These results demonstrate the potential applications of this self-hosted TADF polymer in flexible ink-jet printed OLEDs and, therefore, for a more scalable fabrication process.

Wavelength-Gated Photochemical Synthesis of Phenalene Diimides.

Herein, we pioneer a wavelength-gated synthesis route to phenalene diimides. Consecutive Diels-Alder reactions of methylisophthalaldehydes and maleimides afford hexahydro-phenalene-1,6-diol diimides via 5-formyl-hexahydro-benzo[f]isoindoles as the intermediate. Both photoreactions are efficient (82-99 % yield) and exhibit excellent diastereoselectivity (62-98 % d.r.). The wavelength-gated nature of the stepwise reaction enables the modular construction of phenalene diimide scaffolds by choice of substrate and wavelength. Importantly, this synthetic methodology opens a facile avenue to a new class of persistent phenalenyl diimide neutral radicals, constituting a versatile route to spin-active molecules.

DESolution of CD and CB Macrocycles.

Supramolecular chemistry utilizing the macrocyclic hosts cyclodextrins (CDs) and cucurbit[n]urils (CB[n]s) is traditionally performed in aqueous media; however, their solubility is typically poor, especially for the family of CB[n]s. Through derivatization of these macrocycles their solubility can be augmented to enable enhanced solubility in water and in some organic solvents. The increase in solubility of these derivatized macrocycles allows for their use in a wider range of chemical environments and giving rise to myriad potential applications. The dissolution of parent CDs (α-, ß- and γ-) and CB[n]s (n=6-8) in deep eutectic solvents (DES) is reported, showing dramatic enhanced solubility of the larger species in both families, CB[7] and CB[8] as well as ß- and γ-CD, respectively. Furthermore, the host-guest properties are maintained in this new solvation medium.

Expanding the Scope of Electron-Deficient C-H Building Blocks: Direct Arylation of Pyromellitic Acid Diimide.

Direct C-H activation of pyromellitic diimide (PMDI) is reported for the first time. The method avoids cumbersome pathways involving bromination usually required for further cross-coupling. Good to excellent yields of mono- and di-substituted PMDI derivatives can be obtained under optimized reaction conditions. The reaction scope was also explored, and the materials were characterized with respect to their thermal, optical, and electronic properties.