Intrinsically Stretchable Electroluminescent Elastomers with Self-Confinement Effect for Highly Efficient Non-Blended Stretchable OLEDs.

Ultra-flexible stretchable organic light-emitting diodes (OLEDs) are emerging as a basic component of flexible electronics and human-machine interfaces. However, the brightness and efficiency of stretchable OLEDs remain still far inferior to their rigid counterparts, owing to the scarcity of satisfactory stretchable electroluminescent materials. Herein, we explore a general concept based on the self-confinement effect to dramatically improve the stretchability of elastomers, without affecting electroluminescent properties. The balanced rigid/flexible chain dynamics under self-confinement significantly reduces the modulus of the elastomers, resulting in the maximum strain reaching 806 %. Ultra-flexible stretchable OLEDs have been constructed based on the resulting ISEEs, achieving unprecedented high-performance non-blended stretchable OLEDs. The results suggest an effective molecular design strategy for highly deformable stretchable displays and flexible electronics.

Highly Regioselective Direct C-H Arylation: Facile Construction of Symmetrical Dithienophthalimide-Based π-Conjugated Molecules for Optoelectronics.

Controllable direct C-H arylation with high regioselectivity is highly desirable yet remains a formidable challenge. Herein, a facile regioselective direct C-H arylation is developed for efficient construction of a variety of symmetrical dithienophthalimide-based π-conjugated molecules. The resulting methodology is applicable to a wide range of substrates, from electron-rich units to electron-deficient units with large steric end groups. Aryl halides have been confirmed to be able to couple with dithienophthalimide (DTI) via direct C-H arylation, showing high regioselectivity. Varying the functional end groups onto the DTI core has been demonstrated to fine tune the emission colors to cover most of the visible spectra. The results suggest a facile strategy towards highly selective direct C-H arylation, opening the prospects towards efficient construction of π-conjugated molecules for various potential optoelectronic applications.

Self-templated synthesis of uniform hollow spheres based on highly conjugated three-dimensional covalent organic frameworks.

Covalent organic frameworks (COFs) have served as a family of porous crystalline molecules for various promising applications. However, controllable synthesis of COFs with uniform morphology is paramount yet still remains quite challenging. Herein, we report self-templated synthesis of uniform and unique hollow spheres based on highly conjugated three-dimensional (3D) COFs with diameters of 500-700 nm. A detailed time-dependent study reveals the continuous transformation from initial nano sphere-like particles into uniform hollow spherical structures with Ostwald ripening mechanism. Particularly, the resulting 3D COF (3D-Sp-COF) is prone to transport ions more efficiently and the lithium-ion transference number (t+) of 3D-Sp-COF reaches 0.7, which even overwhelms most typical PEO-based polymer electrolytes. Inspiringly, the hollow spherical structures show enhanced capacitance performance with a specific capacitance of 251 F g-1 at 0.5 A g-1, which compares favorably with the vast majority of two-dimensional COFs and other porous electrode materials.

Diindolotriazatruxene-Based Hole-Transporting Materials for High-Efficiency Planar Perovskite Solar Cells.

A novel set of hole-transporting materials (HTMs) based on π-extended diindolotriazatruxene (DIT) core structure with electron-rich methoxy-engineered functional groups were designed and synthesized via a facile two-step procedure. All compounds were afforded from inexpensive precursors without a complex purification process. Cyclic voltammograms indicate that the resulting HTMs exhibit suitable highest occupied molecular orbital (HOMO) energy levels, which facilitate efficient hole injection from the valence band of perovskites into the HOMO of DIT-based HTMs as confirmed by time-resolved photoluminescence. Notable power conversion efficiency of the planar perovskite solar cells with low-temperature device fabrication achieved 18.21% utilizing D2, which is competitive with the corresponding devices based on the common Spiro-OMeTAD-based HTMs. The results manifest that DIT-based compounds are promising HTMs for constructing high-efficiency planar perovskite solar cells with low-cost solution processing procedures.

Redox-active triazatruxene-based conjugated microporous polymers for high-performance supercapacitors.

Conjugated polymers (CPs) have been intensively explored for various optoelectronic applications in the last few decades. Nevertheless, CP based electrochemical energy storage devices such as supercapacitors remain largely unexplored. This is mainly owing to the low specific capacitance, poor structural/electrochemical stability, and low energy density of most existing CPs. In this contribution, a novel set of redox-active conjugated microporous polymers, TAT-CMP-1 and TAT-CMP-2, based on nitrogen-rich and highly conductive triazatruxene building blocks, were successfully designed and synthesized to explore their potential application as efficient and stable electrode materials for supercapacitors. Despite a moderate surface area of 88 m2 g-1 for TAT-CMP-1 and 106 m2 g-1 for TAT-CMP-2, exceptional specific capacitances of 141 F g-1 and 183 F g-1 were achieved at a current density of 1 A g-1. The resulting polymers exhibited unusually high areal specific capacitance (>160 µF cm-2), which is attributed to the pseudocapacitance resulting from redox-active structures with high nitrogen content. More importantly, the TAT-CMP-2 electrode exhibits excellent cycling stability: only 5% capacitance fading is observed after 10 000 cycles at a high current density of 10 A g-1, enabling the possible use of these materials as electrodes in electrochemical devices.

A T-shaped triazatruxene probe for the naked-eye detection of HCl gas with high sensitivity and selectivity.

A T-shaped Schiff-base triazatruxene derivative (TATNFF) was designed, synthesized, and explored as a sensitive probe to detect HCl gas by the naked eye. The remarkable color change of TATNFF with turn-on behavior in the presence of a trace amount of HCl gas was obviously observed by the naked eye, which opens up a new strategy to explore a novel set of smart responsive materials for sensing applications.

Synthesis and characterization of symmetric cyclooctatetraindoles: exploring the potential as electron-rich skeletons with extended π-systems.

A facile one-pot tetramerization of indolin-2-one with phosphoryl chloride was applied for the first convenient direct synthesis of C2v-symmetric cyclooctatetraindole with an 8π annulene as the center. Tetra- and octa-arylated cyclooctatetraindole derivatives functionalized with fluorescent fluorene and pyrene units were thus facilely synthesized and characterized.

Activation of ERK1/2 and Akt is associated with cisplatin resistance in human lung cancer cells.

Cisplatin is widely used for the treatment of solid tumours including small cell lung cancers, but its success is often compromised by relapse and resistance to further treatment. Extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt are two major cell survival pathways that are upregulated and activated in lung cancer tissues. Phosphorylated ERK1/2 (p-ERK1/2) and Akt (p-Akt) can be further stimulated by chemotherapeutics in cancer cells. Although individually targeting the ERK1/2 or Akt pathway has been reported to sensitize cancer cells to therapy, the effect of concurrently blocking these two pathways on the sensitivity of lung cancer cells to cisplatin has not been investigated. In the present study, we aimed to determine whether the ERK1/2 and Akt pathways contribute to cisplatin resistance in human small cell lung cancer A549 cells. The results showed that cisplatin activates p-ERK1/2 and p-Akt in A549 cells. Blockade of either of these pathways with chemical inhibitors moderately sensitized A549 cells to cisplatin-induced apoptosis and reduced cell viability. Strikingly, concurrent inhibition of p-ERK1/2 and p-Akt significantly potentiated cisplatin cytotoxicity in vitro and in vivo. The sensitization of A549 cells to cisplatin cytotoxicity induced by p-Akt inhibition was mediated by the upregulation of PUMA, whereas that induced by p-ERK1/2 inhibition occurred by Bcl-2 downregulation. These data indicate that the cooperative effects of p-ERK1/2 and p-Akt on attenuating cisplatin cytotoxicity are mediated by PUMA and Bcl-2 regulation, and concurrently blocking these pathways may be an effective strategy for improving the efficacy of cisplatin as anticancer treatment.