Zilong Wang

Pyrene-fused Acenes and Azaacenes: Synthesis and Applications.

In this account, the synthesis and applications of pyrene-fused acenes, as well as pyrene-fused azaacenes, have been carefully reviewed. Moreover, the synthetic methods involving two key synthons (different lengths of dienes and ynes) have been included. Furthermore, the clean reaction strategy has been introduced for the preparation of pyrene-fused acenes with a single terminal-pyrene unit from tetracene to octacene, as well as for the synthesis of pyrene-fused octatwistacenes and nonatwistacenes with double terminal-pyrene units. Similarly, the synthons and the synthetic methods for pyrene-fused azaacenes have also been summarized. The applications of pyrene-fused acenes and pyrene-fused azaacenes have been included.

An Azaacene Derivative as Promising Electron-Transport Layer for Inverted Perovskite Solar Cells

It is highly desirable to develop novel n-type organic small molecules as an efficient electron-transport layer (ETL) for the replacement of PCBM to obtain high-performance metal-oxide-free, solution-processed inverted perovskite solar cells (PSCs) because this type of solar cells with a low-temperature and solution-based process would make their fabrication more feasible and practical. In this research, the new azaacene QCAPZ has been synthesized and employed as non-fullerene ETL material for inverted PSCs through a solution-based process without the need for additional dopants or additives. The as-fabricated inverted PSCs show a power conversion efficiency up to 10.26u2009%. Our results clearly suggest that larger azaacenes could be promising electron-transport materials to achieve high-performance solution-processed inverted PSCs.

Solution-processable thiadiazoloquinoxaline-based donor–acceptor small molecules for thin-film transistors

Although several [1,2,5]thiadiazolo[3,4-g]quinoxaline (TQ)–thiophene-based hybrid polymers have been demonstrated for application in organic field-effect transistors (OFETs), the research on the charge carrier mobility of conjugated donor (D)–acceptor (A) small molecules is rare. To enrich the TQ-containing small molecule family, in this paper, we designed and synthesized three novel TQ derivatives 1, 2, and 3 with thiophene units attached onto the TQ cores. The optoelectronic and OFET properties of as-prepared compounds 1–3 are investigated. Our results indicate that compounds 1–3 show typical p-type characteristics with mobility as high as 0.012, 0.05 and 0.0055 cm2 V−1 s−1 and on/off current ratios of 3 × 105, 1 × 106 and 1 × 104 under the optimized conditions, respectively. Due to the steric effect of the substituted bulky group, compound 3 adopts a looser packing mode with a larger π–π distance, which subsequently reduces the transport performance. Our results suggest that the D–A π-conjugated small molecules based on TQ could be good candidates for application in organic electronic devices.

Azaacenes as active elements for sensing and bio applications

Since azaacenes have electron-deficient backbones and lone-pair electrons on nitrogen centers, they can efficiently detect the target molecules or ions through supramolecular interactions such as anion-π attractions and coordinate bonding. These special features make azaacenes very designable for various sensors, which can be further used in the bio field. In this review, we will summarize the recent progress in the applications of azaacenes in sensing and bio fields. We believe that a rapid development in the research of sensors and bio applications based on azaacenes will be witnessed in the coming years due to their tuneable structures, optical properties and binding abilities.

Full Characterization and Photoelectrochemical Behavior of Pyrene-fused Octaazadecacene and Tetraazaoctacene.

The preparation of large azaacenes is very important because of their great potential in organic electronics. In this report, we successfully synthesized and fully characterized two stable pyrene-fused large azaacenes: octaazadecacene and tetraazaoctacene through employing a relatively moderate aromatic unit pyrene as imbedded species in the backbone of azaacenes to ensure large conjugation and stability. The photoelectrochemical (PEC) studies indicate that both azaacenes display n-type semiconductor behavior.

An ambipolar azaacene as a stable photocathode for metal-free light-driven water reduction

Present photoelectrochemical (PEC) cells for water splitting are based on inorganic electrodes. For future large-scale applications, electrodes that are metal-free, of low cost, and with sustainable availability are crucial. Herein, we report a new ambipolar larger azaacene (DQNDN) as a single-active-element-based photocathode in PEC cells with a current density of 0.13 mA cm−2 at −0.13 V versus RHE.

A Colorimetric and Fluorimetric Chemodosimeter for Copper Ion Based on the Conversion of Dihydropyrazine to Pyrazine

In this research, we successfully synthesized and fully characterized the new compound 5,8,13,16,21,24-hex-(triisopropylsilyl)ethynyl)-6,23-dihydro-6,7,14,15,22,23-hexaza-trianthrylene (HHATA, brown color in a mixed solvent of CH2 Cl2 /CH3 CN 1:1, v/v, weakly blue fluorescent), which can be easily oxidized to 5,8,13,16,21,24-hex-(triisopropylsilyl)ethynyl)-6,7,14,15,22,23-hexazatrianthrylene (HATA) (yellow color in CH2 Cl2 /CH3 CN 1:1, v/v), red fluorescent) by Cu(2+) ions. This reaction only proceeds efficiently in the presence of Cu(2+) ions when compared with other common metal ions such as Fe(3+) , Co(2+) , Mn(2+) , Hg(2+) , Ni(2+) , Pb(2+) , Ag(+) , Mg(2+) , Ca(2+) , K(+) , Na(+) , and Li(+) . Our result suggests that this reaction can be developed as an effective method for the detection of Cu(2+) ions.

Synthesis and Exploration of Ladder-Structured Large Aromatic Dianhydrides as Organic Cathodes for Rechargeable Lithium-Ion Batteries

Compared to anode materials in Li-ion batteries, the research on cathode materials is far behind, and their capacities are much smaller. Thus, in order to address these issues, we believe that organic conjugated materials could be a solution. In this study, we synthesized two non-polymeric dianhydrides with large aromatic structures: NDA-4N (naphthalenetetracarboxylic dianhydride with four nitrogen atoms) and PDA-4N (perylenetetracarboxylic dianhydride with four nitrogen atoms). Their electrochemical properties have been investigated between 2.0 and 3.9u2005V (vs. Li+ /Li). Benefiting from multi-electron reactions, NDA-4N and PDA-4N could reversibly achieve 79.7u2009% and 92.3u2009%, respectively, of their theoretical capacity. Further cycling reveals that the organic compound with a relatively larger aromatic building block could achieve a better stability, as an obvious 36.5u2009% improvement of the capacity retention was obtained when the backbone was switched from naphthalene to perylene. This study proposes an opportunity to attain promising small-molecule-based cathode materials through tailoring organic structures.

A novel quinone-based polymer electrode for high performance lithium-ion batteries

Designing of high electrochemical performance organic electrode materials has attracted tremendous attention. Recent investigations revealed that quinone-based polymers along with the stable thioether bonds could achieve a high specific capacity and a good cycling stability simultaneously. In this study, we synthesized a novel ladder-structured polymer poly(2,3-dithiino-1,4- benzoquinone) (PDB) through a simple two-step polymerization. The electrochemical performance indicated that PDB could achieve a high reversible specific capacity of 681 mAh g−1 with 98.4% capacity retention after 100 cycles. A good rate performance was also achieved with a fast recovery of the capacity after testing at different current densities. Ultra-long cycling performance of PDB was also investigated. The promising results of PDB provided us more confidence to continue searching for high performance polymers through the modification of organic structures.摘要近年来, 设计和合成高性能的锂离子电池用有机化合物电极吸引了许多的关注. 很多研究表明基于苯醌和硫醚结构的聚合物可以同时具 有高比容量和稳定的循环效率. 本研究用一个简单的聚合方法合成了一个新型的梯形聚合物聚(2,3-二噻烯-1,4-二苯醌) (PDB). 分析发现此聚合 物具有1050 mAh g−1 的初始可逆比容量, 并且在循环一百次之后还保留有681 mAh g−1 的比容量和98.4%的库伦比效率. 当此聚合物在不同电流 下充放电后并且重新设置回小电流时, 其比容量还可以恢复到之前小电流充放电时的性能, 证明了此聚合物有很好的倍率性能. 进一步大电流 充放电表明此聚合物可以一直持续1000个循环, 再次说明了此聚合物电极的循环稳定性.

Structure engineering: extending the length of azaacene derivatives through quinone bridges

Increasing the length of azaacene derivatives through quinone bridges is very important because these materials could have deep LUMO energy levels and larger overlapping in the solid state, which would have great applications in organic semiconducting devices. Here, two fully characterized large quinone-fused azaacenes Hex-CO and Hept-CO prepared through a novel palladium-catalyzed coupling reaction are reported. Our research clearly proved that the quinone unit can be employed as a bridge to extend the molecular conjugation length, increase the molecular overlapping, and engineer the molecular stacking mode. Hex-CO shows lamellar 2-D π-stacking modes, while Hept-CO shows 1-D π-stacking and adopts a 3-D interlocked stacking mode with the adjacent molecular layers vertical to each other. With the deep LUMO energy levels (∼−4.27 eV), Hex-CO and Hept-CO were both demonstrated to be electron-transport layers. Their charge transport properties were investigated through OFETs and theoretical calculations. Due to the different stacking modes, Hex-CO shows a higher electron mobility of 0.22 cm2 V−1 s−1 than Hept-CO (7.5 × 10−3 cm2 V−1 s−1) in a single-crystal-based OFET. Our results provide a new route for structure engineering through extending the azaacene derivatives by quinone bridges, which can be of profound significance in organic electronics.