Azulene, a nonalternant and nonbenzenoid hydrocarbon, has drawn increasing attention for constructing optoelectronic materials owing to its unique electronic structure and physicochemical properties. It is still a challenge to control the dipole orientation of azulene units in the backbone of 2,6-azulene-based conjugated polymers. Herein, three 2,6-azulene and bi-thieno[3,4-c]pyrrole-4,6-dione (BTPD) based conjugated copolymers P(AzBTPD-1), P(AzBTPD-2), and P(AzBTPD-3) with different dipole arrangements of azulene moieties were synthesized by direct arylation polymerization, where the rational design of the monomers allows for the achievement of the precisely controlled orientation of azulene units in the polymer main chain. The dipole arrangements of 2,6-azulene units were random for P(AzBTPD-1), head-to-head and tail-to-tail-arranged for P(AzBTPD-2) and head-to-tail-arranged for P(AzBTPD-3). High-temperature gel permeation chromatography of P(AzBTPD-1), P(AzBTPD-2), and P(AzBTPD-3) at 150 degrees C with 1,2,4-trichlorobenzene as the eluent gave average molecular weight values of 20.8, 20.7, and 24.1 kDa, respectively, with the corresponding polydispersity index values of 2.22, 2.48, and 2.17, respectively. All three polymers have similar molecular weights, thereby the influence of molecular weight can be ignored. UV-vis absorption spectra and cyclic voltammetry were performed to evaluate the optoelectronic properties of these three polymers. The maximum absorption wavelength of P(AzBTPD-1), P(AzBTPD-2), and P(AzBTPD-3) in thin film showed red shifts (8, 11 and 17 nm) relative to those in chloroform solution. The largest red shift of 17 nm of P(AzBTPD-3) indicated its strong intermolecular interactions in solid state. The energy levels of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of P(AzBTPD-1), P(AzBTPD-2), and P(AzBTPD-3) were -5.27/-3.56 eV, -5.27/-3.58 eV and -5.27/-3.59 eV, respectively, which were acquired by cyclic voltammetry measurements. Due to the electron-withdrawing property of BTPD, these three polymers did not show obvious proton responsiveness, and their UV-vis absorption spectra show no obvious change upon protonation. To investigate the effect of azulene dipole arrangements in the polymeric backbone on the charge transport properties of these polymers, bottom-gate and top-contact organic field-effect transistor (OFET) devices based on these three polymers were fabricated. Under nitrogen atmosphere, all three polymers showed unique n-channel charge transport behaviors. The thermal annealed OFETs based on P(AzBTPD-1), P(AzBTPD-2), and P(AzBTPD-3) showed electron mobilities of 0.011, 0.019 and 0.027 cm(2) V-1 s(-1), respectively. The higher electron-transport ability of P(AzBTPD-3) is consistent with the better degree of polymer order and the lower LUMO energy level obtained from cyclic voltammetry measurement. Examination of thin films via atomic force microscopy (AFM) provides the evidence of the best morphology of P(AzBTPD-3) among three polymers, which is in accordance with its best device performance. The root mean square roughness (RMS) values of thin films of these three polymers decreased after thermal annealing treatment, indicating the improved thin film morphology of these three polymers, which is consistent with the gradually enhanced performance of these polymers' OFET devices. Therefore, regulation the dipole arrangements of 2,6-azulene units in the polymeric backbone is an effective strategy for obtaining high-performance organic optoelectronic materials. Our work not only presented an efficient strategy to achieve the precisely controlled structural regularity of 2,6-azulene-based conjugated polymers, but also gave new insights for the synthetic chemistry of polymers with low-symmetrical conjugated monomers and the study of their structure-property relationships.

Azulene has aroused widespread interest for constructing optoelectronic materials. However, controlling the dipole orientation of 2,6-azulene units in the conjugated polymer backbone is a significant challenge so far. Herein, by C-H activation strategy, three 2,6-azulene-TPD-based conjugated copolymers with different dipole arrangements were synthesized, where TPD = thieno[3,4-c]pyrrole-4,6-dione. The dipole arrangements of 2,6-azulene units were random for P(AzTPD-1), head-tohead/tail-to-tail for P(AzTPD-2), and head-to-tail for P(AzTPD3). These polymers exhibited unipolar n-type semiconductor characteristics in organic field effect transistors. Moreover, regioregular polymer P(AzTPD-3) displayed the best device performance with an electron mobility of up to 0.33 cm2 V-1 s-1, which makes P(AzTPD-3) a high-performance n-type polymeric semiconductor. These results demonstrate that incorporation of 2,6-azulene units into the polymeric backbone together with the regulation of the dipole orientation of 2,6-azulene units is an effective strategy for obtaining high-performance organic optoelectronic materials.

Azulene has attracted significant attention for constructing novel optoelectronic materials. Tuning the dipole orientation of azulene unit in azulene-based conjugated polymers has recently aroused widespread concern and remains a great challenge due to the lack of synthetic method. Herein, we report three 2,6-azulene and 3,4-propylenedioxythiophene (ProDOT) based conjugated copolymers P(AzProDOT-1), P(AzProDOT-2) and P(AzProDOT-3) with different dipole arrangements of azulene moieties. The regioregularity of these 2,6-azulene-ProDOT-based conjugated polymers was tuned by monomer design and direct arylation polymerization strategy, which enables a thorough study of the impact of the regioregularity on the properties of these polymers and their charge transport performance. The dipole orientation of 2,6-azulene units were regiorandom for P(AzProDOT-1), regularity with medium regioregularity for P(AzProDOT-2) and regularity with high regioregularity for P(AzProDOT-3), respectively. The number-average molecular weight values of P(AzProDOT-1), P(AzProDOT-2) and P(AzProDOT-3) estimated by gel permeation chromatography (GPC) were 11.1, 11.4 and 9.3 kDa, respectively, and the chemical structures of these three polymers were also characterized by high-temperature 1H NMR spectra. Ultraviolet-visible (UV-vis) absorption spectra and cyclic voltammetry were conducted to evaluate the optoelectronic properties of these polymers. The blue-shift of the maximum absorption peak for P(AzProDOT-2) indicates its twisted polymer backbone and short effective p-conjugation length, while the red-shift of the maximum absorption peak for P(AzProDOT-3) demonstrates the more planar conjugated skeleton and the longer effective p-conjugation length, although its molecular weight was a little lower. Besides, there was a prominent shoulder peak in the thin film of P(AzProDOT-3) in UV-vis absorption spectrum, indicating the stronger interchain interactions in solid state. All these observations were in agreement with the density functional theory (DFT) calculation results. Due to the electron-donating property of ProDOT, these three polymers displayed strong and sensitive proton responsiveness. The ultraviolet-visible-near infrared (UV-vis-NIR) spectra of these three polymers showed obvious red-shifts (>150 nm) upon protonation, and the films of these polymers also possess strong proton responsiveness properties. Charge-carrier mobilities of these three polymers were measured by the space-charge-limited current (SCLC). The hole mobilities of thin films of P(AzProDOT-1), P(AzProDOT-2) and P(AzProDOT-3) were 1.32x10(-5), 9.14x10(-5) and 1.41x10(-4) cm(2).V-1.s(-1), respectively, and their electron mobilities were 1.62x10(-6), 7.91x10(-6) and 1.66x10-5 cm(2).V-1.s(-1), respectively. The atomic force microscopy (AFM) study demonstrated that the thin film of P(AzProDOT-3) possessed the smoothest surface and the smallest root mean square (RMS) roughness,

Binuclear dianionic cocatalysts can bring cationic active metal centers into close proximity to study center-center enchainment cooperativity effects in olefin polymerization catalysis. The previously reported binuclear diborate cocatalyst, (Ph3C+)(2)[1,4-(C6F5)(3)BC6F4B(C6F5)(3)](2-) (B-2,B-H), is poorly soluble in alkane and aromatic solvents and requires undesirable haloaromatic additives to fully solubilize it for efficient olefin polymerizations. Here, two binuclear diborate-based cocatalysts, (Ar3C+)(2)[1,4-(C6F5)(3)BC6F4B(C6F5)(3)](2-) (B-2,B-t-Bu; Ar = 4-t-Bu-C6H4-; B-2,B-n-octyl; Ar = 4-n-octyl-C6H4-), are synthesized and characterized by multinuclear NMR spectroscopy, density functional theory computation, and by single-crystal diffraction for B-2,B-t-Bu center dot B-2,B-n-octyl exhibits good solubility in low-polarity solvents such as toluene and methylcyclohexane (MeCy), enabling the study of (mu-CH2CH2-3,3'){(eta(5)-indenyl)[1-(MeSi)-Si-2((BuN)-Bu-t)](ZrMe+)(2) [EBICGC(ZrMe+)(2)]-catalyzed ethylene homo- and co-polymerizations in solvent systems of decreasing polarity (toluene/difluorobenzene -> toluene -> MeCy). Product M(w)s are bimodal and sensitive to the above solvent progression, with the high-M-w fraction (wt %) increasing from 41 -> 92 -> 100%, respectively, for ethylene homopolymerization, and from 15 -> 53 -> 93%, respectively, for ethylene + 1-hexene copolymerization. Under scaled/industrial high temperature, higher pressure operating conditions, the same soluble binuclear diborate is an active olefin copolymerization cocatalyst, giving high polymer M(w)s and similar dispersity, D.

Two poly(2,6-azuleneethynylene)s (PAzE-1 and PAzE-2) were designed and synthesized. The 2,6-azulene units are head-to-tail-arranged in PAzE-1, while there are three types of orientations of 2,6-azulene units in PAzE-2: head-to-tail, head-to head, and tail-to-tail segments, of which the head-to-tail one accounts for about 27% (determined from 1H NMR spectra). Such a structural distinction endows the two polymers with different absorption spectra in solution and aggregation states as well as different thin-film morphologies, microstructures, and field-effect transistor (FET) performances, suggesting that the dipole orientation of azulene units in a polymer backbone may be a critical issue that deserves careful consideration during the molecular design and synthesis. PAzE-1 with an ordered dipole orientation has stronger aggregation even in a very dilute solution (10-6 M). PAzE-2 films have a higher in-plane microstructural order and lower surface roughness than PAzE-1 films; hence, the PAzE-2-based transistor devices exhibit 1-2 orders higher hole and electron mobilities. Unlike typical p-type alkyl-substituted poly(p-phenyleneethynylene)s (PPEs), PAzE-1 and PAzE-2 are ambipolar semiconductors.

The annual global production of polyolefin products exceeds 100 million tons, and they are widely used in various fields. In contrast to heterogeneous polymerization that produces polyolefins with broad dispersity, single-site transition-metal-catalyzed homogeneous olefin polymerization enables the synthesis of polyolefins with narrow molecular weight distribution, controllable chain segment length, and uniform insertion ratio. It can flexibly tune the molecular structure of polyolefins to provide polyolefin materials with the required properties, which can be applied to high-end applications such as medical packaging and medical equipment. It is important to choose a suitable combination of a catalyst and cocatalyst to obtain tailor-made polyolefins through high-efficiency homogeneous polymerization. The main function of the cocatalyst is to react with the catalyst precursor to generate and stabilize active metal cations, the latter being the center of catalyzing olefin polymerizations. This review summarizes the most important work regarding cocatalysts in the past two decades, including novel structures: Mono/dinuclear boron-, aluminum-, and polymer-based promoters. This review illustrates the importance of the weakly coordinative nature of the counter anion, providing the design principle for the development of a highly efficient cocatalyst. Activation mechanism: The use of an industrial catalysis-related pyridylamido hafnium complex is an example that showcases the complicated reactions of this catalyst with different cocatalysts, shedding light on the importance of choosing the pair of catalyst and cocatalyst. Applications in polymerization: Binuclear cocatalysts and the cocatalysts combined with coordination chain transfer polymerizations are used to synthesize novel structural polyolefins, indicating that the cocatalyst plays a crucial role in alternating polyolefin structures. Cocatalyst-involved catalyst deactivation reactions: This part emphasizes the reaction pathways of cocatalysts that lead to catalyst deactivation, including the replacement of metal and ligand. Further, this review proposes the possible future development of cocatalysts by investigating the reported compounds with high Lewis acidity and the development of novel functionalized cocatalysts. For instance, the development of external stimuli-responsive cocatalyst structures may be one of the future development directions. Combining cocatalysts with existing catalytic methods, such as the coordinative chain transfer polymerization for synthesizing polyolefins with a novel structure, may be the second development direction in the future. With the advancement of computer hardware and algorithms together with experimental data, computational chemistry helps understand the effect of cocatalysts on polymerization. Predicting the structure of new and efficient cocatalysts through big data and artificial intelligence is the third possible future development direction.

Surface-bound organometallic molecules have recently enabled the development of single-site heterogeneous catalysts, advancing the atomic scale understanding and diversity of heterogeneous catalysis. Here we report that supporting Cp*ZrMe3 (Cat1) on acidic sulfated-alumina (AlS) affords the surface catalyst Cat1/AlS, which was characterized by multi-dimensional solid-state NMR spectroscopies, and is active in ethylene homo- and copolymerizations, as well as propylene and 1-hexene homopolymerizations. In contrast to propylene (or 1-hexene) polymerization by homogeneous Cp*ZrMe2+ B(C6F5)(4)(-) which yields atactic polyolefins, Cat1/AlS promotes remarkable isotacticity with mmmm >95 %. Complementary DFT analysis argues that the restrictive local Cat1/AlS C-1-symmetry favors activation and enchainment at the propylene re enantioface, promoting isotactic polymerization via a "back-skip-like" mechanism.

Significance Solution processing of high-performance, high-Ga-content IGZO thin-film transistors (TFTs)—or compositionally simpler and, hence, technologically more desirable indium gallium oxide (IGO) TFTs—remains challenging and an impediment to manufacturing low-temperature, solution-processed metal oxide electronics. Here, the performance of aqueous solution-processed IGO TFTs is greatly enhanced with polyvinyl alcohol in the precursor solution, yielding a >70-fold increase in electron mobility. By achieving optimal H doping and conversion from six- to four-coordinate Ga, PVA addition suppresses deep trap defect localization. This result not only offers a route to high-performance, ultra-stable metal oxide semiconductor electronics with simple binary compositions, but also provides powerful tools to probe H locations in amorphous metal oxides via a combination of experimental and theoretical approaches.

Modern, enantioselective catalyst development is driven largely by empiricism. Although this approach has fostered the introduction of most of the existing synthetic methods, it is inherently limited by the skill, creativity, and chemical intuition of the practitioner. Herein, we present a complementary approach to catalyst optimization in which statistical methods are used at each stage to streamline development. To construct the optimization informatics workflow, a number of critical components had to be subjected to rigorous validation. First, the critically important molecular descriptors were validated in two case studies to establish the importance of conformation-dependent molecular representations. Next, with a large data set available, it was possible to investigate the amount of data necessary to make predictive models with different modeling methods. Given the commercial availability of many catalyst structures, it was possible to compare models generated with algorithmically selected training sets and commercially available training sets. Finally, the augmentation of limited data sets is demonstrated in a method informed by unsupervised learning to restore the accuracy of the generated models.

Early transition metal catalysts produce high-density and linear low-density polyethylenes with spectacular efficiency. Nevertheless, these catalysts are ineffective in producing low-density polyethylene homopolymers with large –(CH 2 ) x CH 3 branch densities ( x ≥ 5) or low-molecular-mass ( M n < 1,200 g mol −1 ) highly branched polyethylenes (HBPEs). The latter are potential alternative synthetic lubricants that have eluded efficient catalytic synthesis. Here we report the synthesis of low- M n HBPEs with 61–93 branches per 1,000 carbon atoms from abundant ethylene as the primary feedstock using a soluble, highly active ion-paired organozirconium catalyst in a saturated hydrocarbon solvent. The unprecedented activity and branch selectivity reflect previously unrecognized aspects of the cationic catalyst–counteranion pairing in nonpolar media and are characterized spectroscopically and quantum mechanically. The HBPE products are rheologically and tribologically attractive candidates for synthetic lubricants.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Recent decades have witnessed intense research efforts aimed at developing new homogeneous olefin polymerization catalysts, with a primary focus on metal-Cl or metal-hydrocarbyl precursors. Curiously, metal-NR2 precursors have received far less attention. In this contribution, the Zr-amido complex FI2ZrX2 (FI = 2,4-di- tert-butyl-6-((isobutylimino)methyl)phenolate, X = NMe2) is found to exhibit high ethylene polymerization activity and relatively high 1-octene coenchainment selectivity (up to 7.2 mol%) after sequential activation with trimethylaluminum, then Ph3C+B(C6F5)4-. In sharp contrast, catalysts with traditional hydrocarbyl ligands such as benzyl and methyl give low 1-octene incorporation (0-1.0 mol%). This unexpected selectivity persists under scaled/industrial operating conditions and was previously inaccessible with traditional metal-Cl or -hydrocarbyl precursors. NMR, X-ray diffraction, and catalytic control experiments indicate that in this case an FI ligand is abstracted from FI2Zr(NMe2)2 by trimethylaluminum in the activation process to yield a catalytically active cationic mono-FIZr species. Heretofore this process was believed to serve only as a major catalyst deactivation pathway to be avoided. This work demonstrates the importance of investigating diverse precatalyst monodentate σ-ligands in developing new catalyst systems, especially for group 4 olefin polymerization catalysts.

Catalyst design in asymmetric reaction development has traditionally been driven by empiricism, wherein experimentalists attempt to qualitatively recognize structural patterns to improve selectivity. Machine learning algorithms and chemoinformatics can potentially accelerate this process by recognizing otherwise inscrutable patterns in large datasets. Herein we report a computationally guided workflow for chiral catalyst selection using chemoinformatics at every stage of development. Robust molecular descriptors that are agnostic to the catalyst scaffold allow for selection of a universal training set on the basis of steric and electronic properties. This set can be used to train machine learning methods to make highly accurate predictive models over a broad range of selectivity space. Using support vector machines and deep feed-forward neural networks, we demonstrate accurate predictive modeling in the chiral phosphoric acid-catalyzed thiol addition to N-acylimines.

The Mizoroki−Heck reaction is one of the most efficient methods for alkenylation ofaryl, vinyl, and alkyl halides. Due to its innate nature, this protocol requires the employment of compounds possessing a halogen atom at the site of functionalization. However, the accessibility of organic molecules possessing a halogen atom at a particular site in aliphatic systems is extremely limited. Thus, a protocol that would allow a Heck reaction to occur at a specific non-functionalized C(sp3)−H site would be highly desirable.Here, we report a radical relay Heck reaction which allows for a selective remotealkenylation of aliphatic alcohols at unactivated β-, γ- and δ-C(sp3 20 )–H sites. The use of easily installable/removable Si-based auxiliary enables selective I-atom/radical translocation events at remote C−H sites followed by the Heck reaction. Notably, the reaction proceeds smoothly under mild visible light-mediated conditions at room temperature, producing highly modifiable and valuable alkenol products from readily available alcohols feedstocks.

It is a very important and challenging topic to design high performance n-channel organic semiconductors with a new type conjugated skeleton. Herein, a new class of n-channel organic semiconductors, pyrrolo[3,2-b]pyrrole-based quinoidal molecules QBPBP and QFBPBP, was designed and synthesized. Both compounds have low-lying lowest unoccupied molecular orbital energy level and high thermal stability. Single crystal structures reveal they adopt unusual two-dimensional layer-type packing structures in single crystals. Multiple π–π and CN···H interactions are observed in the layer, and alkyl–alkyl chain interactions exist between layers. Transistors based on single ribbons displayed gate voltage-dependent electron mobility with an average of 4.0 cm2 V–1 s–1 and a peak over 6.0 cm2 V–1 s–1 under N2. These results demonstrate pyrrolo[3,2-b]pyrrole-based quinoidal molecules are a new prototype for high performance n-channel organic semiconductors.

A novel mild, visible-light-induced palladium-catalyzed hydrogen atom translocation/atom-transfer radical cyclization (HAT/ATRC) cascade has been developed. This protocol involves a 1,5-HAT process of previously unknown hybrid vinyl palladium radical intermediates, thus leading to iodomethyl carbo- and heterocyclic structures.

采用2-乙基己基磷酸单-2-乙基己基酯(P507)作为萃取剂,磺化煤油为稀释剂,研究了盐酸体系中La3+和Ac3+的萃取分离性能.研究了酸度、萃取剂皂化度、La3+浓度和盐析剂浓度等条件对萃取分离性能的影响.当萃取剂皂化度为30％、母液酸度pH=2.45、La3+质量浓度约32 g/L、盐析剂浓度c(KNO3)=3 mol/L时,该萃取体系对镧锕具有较好的分离效果,分离因子SFLa/Ac可达67.6.采用优化的实验条件,经过扩大实验证明,氧化镧产品中的放射性得到有效去除,氧化镧中227 Ac去除率约89.97％,得到了纯化氧化镧产品.

A. 6H-Benzo[c]chromen-6-one (2). A 1000 mL, double-necked, roundbottomed flask is charged with a Teflon-coated magnetic stir bar (3 cm × 1 cm). To this flask are added biphenyl-2-carboxylic acid 1 (7.93 g, 40 mmol, 1 equiv) (Note 2), potassium peroxydisulfate (21.6 g, 80 mmol, 2 equiv) (Note 3), and silver nitrate (68 mg, 0.01 equiv) (Note 4), followed by water (200 mL) (Note 5) and acetonitrile (200 mL) (Note 6) under an air atmosphere. The flask is equipped with a water-cooling condenser (Note 7) (Figure 1) and a glass stopper. After stirring at 50 °C for 27 h (600 rpm) (Note 8), the reaction mixture is cooled to 23 °C (Figure 2). The reaction mixture is extracted with dichloromethane (3 x 200 mL) (Note 9) AgNO3 (cat) K2S2O8

A general, efficient, and site-selective visible light-induced Pd-catalyzed remote desaturation of aliphatic alcohols into valuable allylic, homoallylic, and bis-homoallylic alcohols has been developed. This transformation operates via a hybrid Pd-radical mechanism, which synergistically combines the favorable features of radical approaches, such as a facile remote CH-HAT step, with that of transition-metal-catalyzed chemistry (selective beta-hydrogen elimination step). This allows achieving superior degrees of regioselectivity and yields in the desaturation of alcohols compared to those obtained by the state-of-the-art desaturation methods. The HAT at unactivated C(sp(3))-H sites is enabled by the easily installable/removable Si-auxiliaries. Formation of the key hybrid alkyl Pd-radical intermediates is efficiently induced by visible light from alkyl iodides and Pd(0) complexes. Notably, this method requires no exogenous photo-sensitizers or external oxidants.

A Pd-II-catalyzed ortho C-H alkoxycarbonylation reaction of aryl silanes toward active hexafluoroisopropyl (HFIP) benzoate esters has been developed. This efficient reaction features high selectivity and good functional-group tolerance. Notably, given the general nature of the silyl-tethered directing group, this method delivers products bearing two independently modifiable sites. NMR studies reveal the presence of hydrogen bonding between HFIP and a pyrimidine nitrogen atom of the directing group, and it is thought to be crucial for the success of this alkoxycarbonylation reaction.