Recent Submissions

  • Topochemical Synthesis of Ca3CrN3H Involving a Rotational Structural Transformation for Catalytic Ammonia Synthesis

    Cao, Yu; Kirsanova, Maria; Ochi, Masayuki; Almaksoud, Walid; Zhu, Tong; Rai, Rohit Kumar; Gao, Shenghan; Tsumori, Tatsuya; Kobayashi, Shintaro; Kawaguchi, Shogo; Abou-Hamad, Edy; Kuroki, Kazuhiko; Tassel, Cédric; Abakumov, Artem; Kobayashi, Yoji; Kageyama, Hiroshi (Angewandte Chemie (International ed. in English), Wiley, 2022-08-05) [Article]
    Topochemical reactions have led to great progress in the discovery of new metastable compounds with novel chemical and physical properties. With these reactions, the overall crystal structure of the host material is generally maintained. Here we report a topochemical synthesis of a hexagonal nitride hydride, h-Ca3CrN3H, by heating an orthorhombic nitride, o-Ca3CrN3, under hydrogen at 673 K, accompanied by a rotational structural transformation. The hydrogen intercalation modifies the Ca-N rock-salt-like atomic packing in o-Ca3CrN3 to a face-sharing octahedral chain in h-Ca3CrN3H, mimicking a 'hinged tessellation' movement. In addition, the h-Ca3CrN3H exhibited stable ammonia synthesis activity when used as a catalyst.
  • Immunoinformatics-Aided Design and In Vivo Validation of a Peptide-Based Multiepitope Vaccine Targeting Canine Circovirus

    Kaushik, Vikas; Jain, Pankaj; Akhtar, Nahid; Joshi, Amit; Gupta, Lovi Raj; Grewal, Ravneet Kaur; Oliva, Romina; Shaikh, Abdul Rajjak; Cavallo, Luigi; Chawla, Mohit (ACS Pharmacology & Translational Science, American Chemical Society (ACS), 2022-08-03) [Article]
    Canine circovirus (CanineCV) is a deadly pathogen affecting both domestic and wild carnivores including dogs. No vaccine against CanineCV is available commercially or under clinical trials. In the present study, we have designed a promising multiepitope vaccine (MEV) construct targeting multiple strains of CanineCV. A total of 545 MHCII binding CD4+T cell epitope peptides were predicted from the capsid and replicase protein from each strain of CanineCV. Five conserved epitope peptides among the three CanineCV strains were selected. The final vaccine was constructed using antigenic, nontoxic, and conserved multiple epitopes identified in silico. Further, molecular docking and molecular dynamics simulations predicted stable interactions between the predicted MEV and canine receptor TLR-5. To validate antigenicity and immunogenicity, one of the mapped epitope peptides was synthesized. In vivo analysis of the selected epitope clearly indicates CD4+T-cell-dependent generation of antibodies which further suggests that the designed MEV construct holds promise as a candidate for vaccine against CanineCV.
  • Bi12O17Cl2 with a Sextuple BiO Layer Composed of Rock-Salt and Fluorite Units and its Structural Conversion through Fluorination to Enhance Photocatalytic Activity

    Kato, Daichi; Tomita, Osamu; Nelson, Ryky; Kirsanova, Maria A.; Dronskowski, Richard; Suzuki, Hajime; Zhong, Chengchao; Tassel, Cédric; Ishida, Kohdai; Matsuzaki, Yosuke; Brown, Craig M.; Fujita, Koji; Fujii, Kotaro; Yashima, Masatomo; Kobayashi, Yoji; Saeki, Akinori; Oikawa, Itaru; Takamura, Hitoshi; Abe, Ryu; Kageyama, Hiroshi; Gorelik, Tatiana E.; Abakumov, Artem M. (Advanced Functional Materials, Wiley, 2022-08-02) [Article]
    Layered bismuth oxyhalides with bilayered (Bi2O2) fluorite (FL) slabs are promising visible-light photocatalysts because of their excellent stability and the ability to adjust band levels depending on the layers combined. It is interesting to manipulate the Bi2O2 slab itself, but only trilayered FL blocks (e.g., Bi3O4) are reported so far. Here, a structurally uncharacterized Bi12O17Cl2, which is extensively studied as a photocatalyst for a variety of reactions, has a sextuple Bi6O8.5 block separated by Cl is shown. Unlike double and triple layered cases, the inner region of the Bi6O8.5 block contains 1D rock-salt (RS) units in the FL matrix along the a-axis, causing in-plane corrugation. A topochemical reaction involving anion-exchange gives Bi12O17–0.5xFxCl2 (x ≤ 6) with alternate FL and RS slabs along the c-axis. The elimination of the structural corrugation increases higher photo-conductivity and improves photocatalytic activity against acetic acid decomposition under visible light irradiation. This study paves new opportunities of controlling the properties of layered bismuth oxyhalides by the thickness of Bi–O block, FL/RS configuration, and structural modulation.
  • Unblocking Ion-occluded Pore Channels in Poly(triazine imide) Framework for Proton Conduction

    Chi, Heng-Yu; Chen, Cailing; Zhao, Kangning; Villalobos, Luis Francisco; Schouwink, Pascal Alexander; Piveteau, Laura; Marshall, Kenneth Paul; Liu, Qi; Han, Yu; Agrawal, Kumar Varoon (Angewandte Chemie (International ed. in English), 2022-07-30) [Article]
    Poly(triazine imide) or PTI is an ordered graphitic carbon nitride hosting Å-scale pores attractive for selective molecular transport. AA'-stacked PTI layers are synthesized by ionothermal route during which ions occupy the framework and occlude the pores. Synthesis of ion-free PTI hosting AB-stacked layers has been reported, however, pores in this configuration are blocked by the neighboring layer. The unavailability of open pore limits application of PTI in molecular transport. Herein, we demonstrate acid treatment for ion depletion which maintains AA' stacking and results in open pore structure. We provide first direct evidence of ion-depleted open pores by imaging with the atomic resolution using integrated differential phase-contrast scanning transmission electron microscopy. Depending on the extent of ion-exchange, AA' stacking with open channels and AB stacking with closed channels are obtained and imaged for the first time. The accessibility of open channels is demonstrated by enhanced proton transport through ion depleted PTI.
  • Surface decorated Ni sites for superior photocatalytic hydrogen production

    Huang, Wenhuan; Bo, Tingting; Zuo, Shouwei; Wang, Yunzhi; Chen, Jiamin; Ould-Chikh, Samy; Li, Yang; Zhou, Wei; Zhang, Jing; Zhang, Huabin (SusMat, Wiley, 2022-07-30) [Article]
    Precise construction of isolated reactive centers on semiconductors with well-controlled configurations affords a great opportunity to investigate the reaction mechanisms in the photocatalytic process and realize the targeted conversion of solar energy to steer the charge kinetics for hydrogen evolution. In the current research, we decorated isolated Ni atoms on the surface of CdS nanowires for efficient photocatalytic hydrogen production. X-ray absorption fine structure investigations clearly demonstrate the atomical dispersion of Ni sites on the surface of CdS nanowires. Experimental investigations reveal that the isolated Ni atoms not only perform well as the real reactive centers but also greatly accelerate the electron transfer via direct Ni–S coordination. Theoretical simulation further documents that the hydrogen adsorption process has also been enhanced over the semi-coordinated Ni centers through electronic coupling at the atomic scale.
  • Aggregation-Induced Fluorescence Enhancement for Efficient X-ray Imaging Scintillators and High-Speed Optical Wireless Communication

    Wang, Jian-Xin; Wang, Yue; Nadinov, Issatay; Yin, Jun; Gutierrez Arzaluz, Luis; Alkhazragi, Omar; He, Tengyue; Ng, Tien Khee; Eddaoudi, Mohamed; Alshareef, Husam N.; Bakr, Osman; Ooi, Boon S.; Mohammed, Omar F. (ACS Materials Letters, American Chemical Society (ACS), 2022-07-29) [Article]
    Aggregation of some chromophores generates very strong fluorescence signals due to the tight molecular packing and highly restricted vibrational motions in the electronically excited states. Such an aggregation-induced emission enhancement enables great strides in biomedical imaging, security screening, sensing, and light communication applications. Here, we realized efficient utilization of a series of aggregation-induced emission luminogens (AIEgens) in X-ray imaging scintillators and optical wireless communication (OWC) technology. Ultrafast time-resolved laser spectroscopic experiments and high-level density functional theory (DFT) calculations clearly demonstrate that a significant increase in the rotational energy barrier in the aggregated state of AIEgens is observed, leading to highly restricted molecular vibrations and suppressed nonradiative processes. AIEgen-based scintillators exhibit a high X-ray imaging resolution of 16.3 lp mm–1, making them excellent candidates for X-ray radiography and security inspections. In addition, these AIEgens show a broad -3-dB modulation bandwidth of ∼110 MHz and high net data rates of ∼600 Mb/s, demonstrating their high potential for application in the field of high-speed OWC.
  • Rich Indium-Vacancies In2S3 with Atomic p–n Homojunction for Boosting Photocatalytic Multifunctional Properties

    Liu, Yuxin; Chen, Cailing; He, Yiqiang; Zhang, Zhe; Li, Mingbian; Li, Chunguang; Chen, Xiao-Bo; Han, Yu; Shi, Zhan (Small, Wiley, 2022-07-27) [Article]
    Design and development of highly efficient photocatalytic materials are key to employ photocatalytic technology as a sound solution to energy and environment related challenges. This work aims to significantly boost photocatalytic activity through rich indium vacancies (VIn) In2S3 with atomic p–n homojunction through a one-pot preparation strategy. Positron annihilation spectroscopy and electron paramagnetic resonance reveal existence of VIn in the prepared photocatalysts. Mott–Schottky plots and surface photovoltage spectra prove rich VIn In2S3 can form atomic p–n homojunction. It is validated that p–n homojunction can effectively separate carriers combined with photoelectrochemical tests. VIn decreases carrier transport activation energy (CTAE) from 0.64 eV of VIn-poor In2S3 to 0.44 eV of VIn-rich In2S3. The special structure endows defective In2S3 with multifunctional photocatalysis properties, i.e., hydrogen production (872.7 µmol g−1 h−1), degradation of methyl orange (20 min, 97%), and reduction in heavy metal ions Cr(VI) (30 min, 98%) under simulated sunlight, which outperforms a variety of existing In2S3 composite catalysts. Therefore, such a compositional strategy and mechanistic study are expected to offer new insights for designing highly efficient photocatalysts through defect engineering.
  • Highly Efficient Electrocatalytic Oxygen Evolution Over Atomically Dispersed Synergistic  Ni/Co Dual Sites

    Pei, Zhihao; Lu, Xue Feng; Zhang, Huabin; Li, Yunxiang; Luan, Deyan; Lou, Xiong-Wen (David) (Angewandte Chemie International Edition, Wiley, 2022-07-27) [Article]
    Single-atom catalysts (SACs) are being pursued as economical electrocatalysts. However, their low active-site loading, poor interactions, and unclear catalytic mechanism call for significant advances. Herein, atomically dispersed Ni/Co dual sites anchored on nitrogen-doped carbon (a-NiCo/NC) hollow prisms are rationally designed and synthesized. Benefiting from the atomically dispersed dual-metal sites and their synergistic interactions, the obtained a-NiCo/NC sample exhibits superior electrocatalytic activity and kinetics towards the oxygen evolution reaction. Moreover, density functional theory calculations indicate that the strong synergistic interactions from heteronuclear paired Ni/Co dual sites lead to the optimization of the electronic structure and the reduced reaction energy barrier. This work provides a promising strategy for the synthesis of high-efficiency atomically dispersed dual-site SACs in the field of electrochemical energy storage and conversion.
  • Highly selective molecular sieving of cis- over trans-1,2-dichloroethene isomers

    Liu, Xin; Alimi, Lukman Olawale; Khashab, Niveen M. (Chemical Communications, Royal Society of Chemistry (RSC), 2022-07-27) [Article]
    An intrinsically porous trianglimine macrocycle 1 is reported to display energy-efficient and cost-effective adsorptive properties by selectively separating cis-1,2-dichloroethene (cis-DCE) from an equimolar cis- and trans-DCE mixture with a purity of over 96%. The selectivity is enhanced by host/guest C–H⋯π intermolecular interactions. Moreover, the macrocycle can be reused many times without any decrease in performance, which further supports the sustainability of using molecular sieves in chemical separation.
  • High-Performance Copper-Doped Perovskite-Related Silver Halide X-ray Imaging Scintillator

    He, Tengyue; Zhou, Yang; Wang, Xiaojia; Yin, Jun; Gutierrez Arzaluz, Luis; Wang, Jian-Xin; Zhang, Yuhai; Bakr, Osman; Mohammed, Omar F. (ACS Energy Letters, American Chemical Society (ACS), 2022-07-26) [Article]
    Scintillators are critical for high-energy radiation detection across a wide array of potential applications, from medical radiography and safety inspections all the way to space exploration. However, constrained by their current shortcomings, including high-temperature and complex fabrication as well as inherent brittleness and fragility among thick films and bulk crystals, traditional scintillators are finding it difficult to meet the rising demand for cost-effective, ecofriendly, and flexible X-ray detection. Here, we describe the development of high-performance and flexible X-ray scintillators based on films of Cu-doped Cs2AgI3 that exhibit ultrahigh X-ray sensitivity. The materials exhibit a high scintillation light yield of up to 82 900 photons/MeV and a low detection limit of 77.8 nGy/s, which is approximately 70 times lower than the dosage for a standard medical examination. Moreover, richly detailed X-ray images of biological tissue and electronic components with a high spatial resolution of 16.2 lp/mm were obtained using flexible, large-area, solution-processed scintillation screens.
  • Simultaneous Performance and Stability Improvement of a p-Type Organic Electrochemical Transistor through Additives

    Hidalgo, Tania C.; Moser, Maximilian; Cendra, Camila; Nayak, Prem Depan; Salleo, Alberto; McCulloch, Iain; Inal, Sahika (Chemistry of Materials, American Chemical Society (ACS), 2022-07-25) [Article]
    Advancements in organic electrochemical transistor (OECT) applications have been largely driven by the development of organic electronic materials that allow for simultaneous ionic and electronic transport in the bulk of their films. These studies focus on achieving high steady-state OECT performance, governed by the electronic charge mobility and the capacitance of the polymer film in the channel, and an often underlooked property is the long-term operational stability. In this work, we present a strategy to improve the performance of p-type OECTs along with operational stability via two additives, i.e., a high-boiling-point solvent (chlorobenzene) and a Lewis acid (tris(pentafluoro phenyl)borane). Addition of a small amount of a cosolvent additive changes the arrangement of glycolated thiophene-based copolymer chains on the substrate toward a direction that allows for more efficient hole transport. The Lewis acid, on the other hand, boosts the OECT stability, mainly by preventing oxidative degradation. Using both additives in the solution grants OECTs with high operational stability and performance through changes in the film microstructure and the polymer’s sensitivity to oxygen. This study highlights the use of additives as a means to enhance the OECT figure of merits without the need for new polymer synthesis.
  • Novel Tpms Contactors Designed with Imprinted Porosity: Numerical Evaluation of Momentum and Energy Transport

    Grande, Carlos; Asif, Mohammad (Elsevier BV, 2022-07-25) [Preprint]
    Structured packings in reactors and separation processes have an extensive trait for process intensification such as enhancement in mass and heat transport without having any substantial pressure drop and can now successfully be produced by using additive manufacturing methods such as 3D printing. Structured packings manufactured with Triply Periodical Minimum Surfaces (TPMS) have good mixing properties and enhanced thermal transport, but they do not have high surface areas.In this work, we report a new type of hybrid TPMS structures with high surface area while keeping good mixing properties. The new shapes are made by generating solids on the boundaries of a 2D tessellation of polygons over the TPMS surface. The new shapes have a higher surface area than a TPMS and at the same time, a higher porosity. We have evaluated the pressure drop and heat transfer properties of such structures for Reynolds numbers 1-200 in ten different solids. The results indicate that pressure drop is dominated by porosity. Heat transfer properties however depend also on available surface area and thus are improved in the porous structures.
  • Maximizing Active Fe Species in ZSM-5 Zeolite Using Organic-Template-Free Synthesis for Efficient Selective Methane Oxidation

    Cheng, Qingpeng; Li, Guanna; Yao, Xueli; Zheng, Lirong; Wang, Junhu; Emwas, Abdul-Hamid M.; Castaño, Pedro; Ruiz-Martinez, Javier; Han, Yu (Research Square Platform LLC, 2022-07-22) [Preprint]
    The selective oxidation of CH4 in the aqueous phase to produce valuable chemicals has attracted considerable research attention due to its mild reaction conditions and simple process. As the most widely studied catalyst for this reaction, Fe-containing ZSM-5 zeolite (Fe-ZSM-5) demonstrates high intrinsic activity and selectivity; however, Fe-ZSM-5 prepared using conventional methods has a limited number of active Fe sites, resulting in low CH4 conversion per unit mass of the catalyst. To address this issue, this study reports a facile organic-template-free synthesis strategy that enables the incorporation of more Fe into the zeolite framework with a higher dispersion degree compared to conventional synthesis methods. Because framework Fe incorporated in this way is more readily to transform into isolated extra-framework Fe species under thermal treatment, the overall effect is that Fe-ZSM-5 prepared using this method (Fe-HZ5-TF) has three times as many catalytically active sites as conventional Fe-ZSM-5. When used for the selective oxidation of CH4 (30.5 bar) with 0.5 M H2O2 at 75°C, Fe-HZ5-TF produced a record high C1 oxygenate yield of 106.3 mmol gcat−1 h− 1 (a HCOOH selectivity of 91.3%), surpassing other catalysts reported to date. Spectroscopic characterization and density functional theory calculations revealed that the active sites in Fe-HZ5-TF are mononuclear Fe species in the form of [(H2O)3Fe(IV) = O]2+ bound to Al pairs in the zeolite framework. This differs from conventional Fe-ZSM-5, where binuclear Fe acts as the active site. Analysis of the catalyst and product evolution during the reaction suggests a radical-driven pathway to explain CH4 activation at the mononuclear Fe site and subsequent conversion to C1 oxygenates.
  • Direct Band Gap in Multilayer Transition Metal Dichalcogenide Nanoscrolls with Enhanced Photoluminescence

    Lin, Ci; Cai, Liang; Fu, Jui-Han; Sattar, Shahid; Wang, Qingxiao; Wan, Yi; Tseng, Chien-Chih; Yang, Chih-Wen; Aljarb, Areej; Jiang, Ke; Huang, Kuo-Wei; Li, Lain-Jong; Canali, Carlo Maria; Shi, Yumeng; Tung, Vincent (ACS Materials Letters, American Chemical Society (ACS), 2022-07-20) [Article]
    A direct band gap that solely exists in monolayer semiconducting transition metal dichalcogenides (TMDs) endows strong photoluminescence (PL) features, whereas multilayer TMD structures exhibit quenched PL due to the direct-to-indirect band gap transition. We demonstrate multilayer TMD (such as MoS2 and WS2) nanoscrolls with a preserved direct band gap fabricated by an effective and facile method of solvent-driven self-assembly. The resultant multilayer nanoscrolls, exhibiting up to 11 times higher PL intensity than the remanent monolayer, are carefully characterized using PL spectroscopy. Significantly enlarged interlayer distances and modulated interlayer coupling in the fabricated nanostructures are unveiled by cross-sectional scanning transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The preservation of direct band gap features is further evidenced by density functional theory calculations using the simplified bilayer model with an experimentally obtained 15 Å interlayer distance. The modulation of the PL intensity as an indicator of the band gap crossover in the TMD nanoscrolls is demonstrated by removing the acetone molecules trapped inside the interlayer space. The general applicability of the method presents an opportunity for large-scale fabrication of a plethora of multilayer TMD nanoscrolls with direct band gaps.
  • High-Performance Scientific Applications Using Mixed Precision and Low-Rank Approximation Powered by Task-based Runtime Systems

    Alomairy, Rabab M. (2022-07-20) [Dissertation]
    Advisor: Keyes, David E.
    Committee members: Moshkov, Mikhail; Hadwiger, Markus; Ltaief, Hatem
    To leverage the extreme parallelism of emerging architectures, so that scientific applications can fulfill their high fidelity and multi-physics potential while sustaining high efficiency relative to the limiting resource, numerical algorithms must be redesigned. Algorithmic redesign is capable of shifting the limiting resource, for example from memory or communication to arithmetic capacity. The benefit of algorithmic redesign expands greatly when introducing a tunable tradeoff between accuracy and resources. Scientific applications from diverse sources rely on dense matrix operations. These operations arise in: Schur complements, integral equations, covariances in spatial statistics, ridge regression, radial basis functions from unstructured meshes, and kernel matrices from machine learning, among others. This thesis demonstrates how to extend the problem sizes that may be treated and to reduce their execution time. Two “universes” of algorithmic innovations have emerged to improve computations by orders of magnitude in capacity and runtime. Each introduces a hierarchy, of rank or precision. Tile Low-Rank approximation replaces blocks of dense operator with those of low rank. Mixed precision approximation, increasingly well supported by contemporary hardware, replaces blocks of high with low precision. Herein, we design new high-performance direct solvers based on the synergism of TLR and mixed precision. Since adapting to data sparsity leads to heterogeneous workloads, we rely on task-based runtime systems to orchestrate the scheduling of fine-grained kernels onto computational resources. We first demonstrate how TLR permits to accelerate acoustic scattering and mesh deformation simulations. Our solvers outperform the state-of-art libraries by up to an order of magnitude. Then, we demonstrate the impact of enabling mixed precision in bioinformatics context. Mixed precision enhances the performance up to three-fold speedup. To facilitate the adoption of task-based runtime systems, we introduce the AL4SAN library to provide a common API for the expression and queueing of tasks across multiple dynamic runtime systems. This library handles a variety of workloads at a low overhead, while increasing user productivity. AL4SAN enables interoperability by switching runtimes at runtime, which permits to achieve a twofold speedup on a task-based generalized symmetric eigenvalue solver.
  • Borinane Boosted Bifunctional Organocatalysts for Ultrafast Ring-Opening Polymerization of Cyclic Ethers

    Chen, Chao; Gnanou, Yves; Feng, Xiaoshuang (Research Square Platform LLC, 2022-07-19) [Preprint]
    The design of reactive species that can either serve to initiate the ring-opening polymerization (ROP) of epoxides for the synthesis of high molar mass polyethers or be alternatively used to catalyze the synthesis of polyether telechelics in the presence of chain transfer agents (CTAs) has long been an elusive goal. Here we report the synthesis of a series of bifunctional borinane-based catalysts that enable the living ROP of epoxides with unprecedented activity (TOF ≥ 1.8×105 h− 1) and molar mass up to 106 g/mol under mild conditions. When used along with CTAs to generate low Mn telechelics, the same borinane-based catalysts exhibit ultrahigh productivity even for loading amounts as low as 50 ppb for ethylene oxide polymerization. These newly designed catalysts also afford the polymerization of oxetane with record TOF values and molar masses. DFT computation provides a full understanding of how these bifunctional catalysts operate when used in the ROP of epoxides.
  • Switching Electrolyte Interfacial Model to Engineer Solid Electrolyte Interface for Fast Charging and Wide-Temperature Lithium-Ion Batteries

    Liu, Gang; Cao, Zhen; Wang, Peng; Ma, Zheng; Zou, Yeguo; Sun, Qujiang; Cheng, Haoran; Cavallo, Luigi; Li, Shiyou; Li, Qian; Ming, Jun (Advanced Science, Wiley, 2022-07-17) [Article]
    Engineering the solid electrolyte interphase (SEI) that forms on the electrode is crucial for achieving high performance in metal-ion batteries. However, the mechanism of SEI formation resulting from electrolyte decomposition is not fully understood at the molecular scale. Herein, a new strategy of switching electrolyte to tune SEI properties is presented, by which a unique and thinner SEI can be pre-formed on the graphite electrode first in an ether-based electrolyte, and then the as-designed graphite electrode can demonstrate extremely high-rate capabilities in a carbonate-based electrolyte, enabling the design of fast-charging and wide-temperature lithium-ion batteries (e.g., graphite | LiNi0.6Co0.2Mn0.2O2 (NCM622)). A molecular interfacial model involving the conformations and electrochemical stabilities of the Li+-solvent-anion complex is presented to elucidate the differences in SEI formation between ether-based and carbonate-based electrolytes, then interpreting the reason for the obtained higher rate performances. This innovative concept combines the advantages of different electrolytes into one battery system. It is believed that the switching strategy and understanding of the SEI formation mechanism opens a new avenue to design SEI, which is universal for pursuing more versatile battery systems with greater stability.
  • Brønsted acid catalyzed enantioselective addition of hydrazones to 3-indolylmethanols

    Mader, Steffen; Maji, Modhu Sudan; Atodiresei, Iuliana; Rueping, Magnus (Organic Chemistry Frontiers, Royal Society of Chemistry (RSC), 2022-07-15) [Article]
    The organocatalytic asymmetric addition of hydrazones to indole derivatives in the presence of chiral Brønsted acids is reported. A large variety of substrates are tolerated and the products are obtained in good yields and with excellent enantioselectivities. This metal-free reaction provides a convenient route to enantiopure β-substituted tryptophan derivatives in a concise fashion.
  • Addition of Diquat Enhances the Electron Mobility in Various Non-Fullerene Acceptor Molecules

    Nugraha, Mohamad; Gedda, Murali; Firdaus, Yuliar; Scaccabarozzi, Alberto D.; Zhang, Weimin; Alshammari, Sanaa Hayel Nazil; Aniés, Filip; Adilbekova, Begimai; Emwas, Abdul-Hamid; McCulloch, Iain; Heeney, Martin; Tsetseris, Leonidas; Anthopoulos, Thomas D. (Advanced Functional Materials, Wiley, 2022-07-15) [Article]
    Molecular doping of organic semiconductors is often used to enhance their charge transport characteristics. Despite its success, however, most studies to date concern p-doping with considerably fewer reports involving n-dopants. Here, n-doping of organic thin-film transistors (OTFTs) based on several non-fullerene acceptor (NFA) molecules using the recently developed diquat (DQ) as a soluble molecular dopant is reported. The low ionization potential of DQ facilitates efficient electron transfer and subsequent n-doping of the NFAs, resulting in a consistent increase in the electron field-effect mobility. Solution-processed BTP-eC9 and N3-based OTFTs exhibit significant increase in the electron mobility upon DQ doping, with values increasing from 0.02 to 0.17 cm2 V–1 s–1 and from 0.2 to 0.57 cm2 V–1 s–1, respectively. A remarkable electron mobility of >1 cm2 V–1 s–1 is achieved for O-IDTBR transistors upon optimal doping with DQ. The enhanced performance originates primarily from synergistic effects on electronic transport and changes in morphology, including: i) significant reduction of contact resistances, ii) formation of larger crystalline domains, iii) change of preferred crystal orientation, and iv) alteration in molecular packing motif. This work demonstrates the universality of DQ as an electronic additive for improving electron transport in OTFTs.
  • Engineering MOF surface defects in mixed matrix membranes: An effective strategy to enhance MOF/polymer adhesion and control interfacial gas transport

    Fan, Dong; Ozcan, Aydin; Shekhah, Osama; Semino, Rocio; Eddaoudi, Mohamed; Maurin, Guillaume (Journal of Membrane Science Letters, Elsevier BV, 2022-07-15) [Article]
    MOF/polymer adhesion in Mixed Matrix Membranes (MMMs) has been mainly enhanced so far via MOF and/or polymer functionalization to strengthen the interactions between the two components. This strategy, albeit effective, is generally accompanied by a drop in the permeability and/or selectivity performance of the MMMs. In this contribution, engineering structure defects at the MOF surfaces is proposed as an effective route to create pockets that immobilize part of the polymer chain, which is of crucial importance both to avoid plasticization issues and to enhance the MOF/polymer affinity while overcoming the adhesion/performance trade-off in MMMs. This engineered interfacial interlocking structure also serves as a bridge to accelerate the gas transport from the polymeric region towards the MOF pore entrance. This concept is showcased with a model MMM made of the prototypical UiO-66 MOF and the glassy Polymer of Intrinsic Microporosity-1 (PIM-1) and tested using CO2, CH4 and, N2 as guest species. Our computational findings reveal that a defective UiO-66 MOF surface improves the MOF/PIM-1 adhesion and contributes to accelerate the interfacial gas transport of the slender molecules CO2 and N2 and in a lesser extent of the spherical molecule CH4. This translates into a selective enhancement of the CO2 transport once combined with CH4 which paves the ways toward promising perspective for pre-combustion CO2 capture.

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