bluuebunny/crossref_metadata_2025 huggingface dataset:
Finely Controlled Platinum Nanoparticles over ZnO Nanorods for Selective Hydrogenation of 3‐Nitrostyrene to 3‐Vinylaniline
Authors: Gao Tongtong , Shi Wen , Zhang Ying , Zhang Liyun , Zhang Bingsen , Liu Zhong‐Wen
Published: May 2020

Metallic platinum nanocatalysts play a key role in the liquid‐phase selective hydrogenation of substrates with more than one unsaturated bond. However, the commonly applied explanation for the effects of different electronic and geometric properties of catalysts on reactions remains of a heuristic nature due to the difficulties involved in preparing catalysts with precise structure. In this work, we have directly loaded pre‐synthesized metallic platinum nanoparticles onto well‐structured ZnO nanorods and then subjected them to thermal treatment in a reductive atmosphere for different temperatures. The effects of the different electronic and geometric properties of the catalysts on the selective reduction of 3‐nitrostyrene to 3‐vinylaniline as a model reaction have been rigorously explored through an analysis of the catalyst structures and the activity and selectivity profiles. Both the electron transfer from zinc to platinum and the decreased platinum surface density as a result of the formation of PtZn intermetallic compounds are key factors for improving the selectivity for the desired 3‐vinylaniline. Azobenzene was detected in the reaction with all the Pt/ZnO catalysts after 10–90 min, which indicates that the reaction follows a condensation mechanism.
Highly Oxidized States of Phthalocyaninato Terbium(III) Multiple‐Decker Complexes Showing Structural Deformations, Biradical Properties and Decreases in Magnetic Anisotropy
Authors: Horii Yoji , Damjanović Marko , Ajayakumar M. R. , Katoh Keiichi , Kitagawa Yasutaka , Chibotaru Liviu , Ungur Liviu , Mas‐Torrent Marta , Wernsdorfer Wolfgang , Breedlove Brian K. , Enders Markus , Veciana Jaume , Yamashita Masahiro
Published: May 2020

Presented here is a comprehensive study of highly oxidized multiple‐decker complexes composed of TbIII and CdII ions and two to five phthalocyaninato ligands, which are stabilized by electron‐donating n‐butoxy groups. From X‐ray structural analyses, all the complexes become axially compressed upon ligand oxidation, resulting in bowl‐shaped distortions of the ligands. In addition, unusual coexistence of square antiprism and square prism geometries around metal ions was observed in +4e charged species. From paramagnetic 1H NMR studies on the resulting series of triple, quadruple and quintuple‐decker complexes, ligand oxidation leads to a decrease in the magnetic anisotropy, as predicted from theoretical calculations. Unusual paramagnetic shifts were observed in the spectra of the +2e charged quadruple and quintuple‐decker complexes, indicating that those two species are actually unexpected triplet biradicals. Magnetic measurements revealed that the series of complexes show single‐molecule magnet properties, which are controlled by the multi‐step redox induced structural changes.
Redox‐Active Supramolecular Heteroleptic M4L2L′2 Assemblies with Tunable Interior Binding Site
Authors: Plessius Raoul , Deij Vera , Reek Joost N. H. , van der Vlugt Jarl Ivar
Published: May 2020

Three Pt4L2L′2 heteroleptic rectangles (1–3), containing ditopic redox‐active bis‐pyridine functionalized perylene bisimide (PBI) ligands PBI‐pyr2 (L) are reported. Co‐ligand L′ is a dicarboxylate spacer of varying length, leading to modified overall size of the assemblies. 1H NMR spectroscopy reveals a trend in the splitting and upfield chemical shift of the PBI‐hydrogens in the rectangles with respect to free PBI, most pronounced with the largest strut length (3) and least with the smallest strut length (1). This is attributed to increased rotational freedom of the PBI‐pyr2 ligand over its longitudinal axis (Npy‐Npy), due to increased distance between the PBI‐surfaces, which is corroborated by VT‐NMR measurements and DFT calculations. The intramolecular motion entails desymmetrization of the two PBI‐ligands, in line with cyclic voltammetry (CV) data. The first (overall two‐electron) reduction event and re‐oxidation for 1 display a subtle peak‐to‐peak splitting of 60 mV, whilst increased splitting of this event is observed for 2 and 3. The binding of pyrene in 1 is probed to establish proof of concept of host‐guest chemistry enabled by the two PBI‐motifs. Fitting the binding curve obtained by 1H NMR titration with a 1:1 complex formation model led to a binding constant of 964±55 m−1. Pyrene binding is shown to directly influence the redox‐chemistry of 1, resulting in a cathodic and anodic shift of approximately 46 mV on the first and second reduction event, respectively.
One Terminal Guanosine Flip of Intramolecular Parallel G‐Quadruplex: Catalytic Enhancement of G‐Quadruplex/Hemin DNAzymes
Authors: Cao Yanwei , Li Wenjing , Gao Tian , Ding Pi , Pei Renjun
Published: May 2020

Numerous studies have shown compelling evidence that incorporation of an inversion of polarity site (IPS) in G‐rich sequences can affect the topological and structural characteristics of G‐quadruplexes (G4s). Herein, the influence of IPS on the formation of a previously studied intramolecular parallel G4 of d(G3TG3TG3TG3) (TTT) and its stacked higher‐order structures is explored. Insertion of 3′–3′ or 5′–5′ IPS did not change the parallel folding pattern of TTT. However, both the species and position of the IPS in TTT have a significant impact on the G4 stability and end‐stacking through the alteration of G4–G4 interfaces properties. The data demonstrate that one base flip in each terminal G‐tetrad can stabilize parallel G4s and facilitate intermolecular packing of monomeric G4s. Such modifications can also enhance the fluorescence and enzymatic performances by promoting interactions between parallel G4s with N‐methyl mesoporphyrin IX (NMM) and hemin, respectively.
Fluorescent Metallacycle‐Cored Amphiphilic Nanoparticles Formed by β‐Cyclodextrin‐Based Host–Guest Interactions towards Cancer Theranostics
Authors: Ma Lingzhi , Yang Tianfeng , Li Shuya , Zhang Zeyuan , Lu Shuai , Jeyakkumar Ponmani , Song Zhongxiao , Li Xiaopeng , Yu Guocan , Chu Dake , Liu Hang , Zhang Yanmin , Zhang Mingming
Published: May 2020

Theranostic agents, taking the advantages of both imaging and therapeutic functions, are anticipated to be key components in the development of personalized medicine in which the therapeutic response can be real‐time monitored. Herein, three metallacycles with pendent adamantane groups are prepared by coordination‐driven self‐assembly of PtIIligands with anticancer activities and tetraphenylethylene derivatives with emission. β‐Cyclodextrin, which shows good host–guest interactions with adamantane moieties, was added to form amphiphilic supramolecular nanoparticles with the aim to enhance the aqueous solubilities and bioactivities of these metallacycles. Moreover, when rhodamine‐modified β‐cyclodextrin was used as the carrier, the release of the metallacycles from the nanoparticles could be monitored in situ through the fluorescence changes owing to the efficient fluorescence resonance energy transfer from the metallacycles to rhodamine‐modified β‐cyclodextrin. In vitro and in vivo studies showed that these nanoparticles not only served as cell imaging contrast agents but also displayed improved anticancer activities, allowing them to serve as potential candidates for cancer theranostics. This study provides a simple and efficient method to prepare theranostic agents by hierarchical supramolecular self‐assembly, which will pave the way for image‐guided cancer therapy, targeted cancer therapy, and related biomedical fields.
Solvent‐Dependent Growth and Stabilization Mechanisms of Surfactant‐Free Colloidal Pt Nanoparticles
Authors: Quinson Jonathan , Neumann Sarah , Kacenauskaite Laura , Bucher Jan , Kirkensgaard Jacob J. K. , Simonsen Søren B. , Theil Kuhn Luise , Zana Alessandro , Vosch Tom , Oezaslan Mehtap , Kunz Sebastian , Arenz Matthias
Published: May 2020

Understanding the formation of nanoparticles (NPs) is key to develop materials by sustainable routes. The Co4CatTM process is a new synthesis of precious metal NPs in alkaline mono‐alcohols well‐suited to develop active nanocatalysts. The synthesis is ‘facile’, surfactant‐free and performed under mild conditions like low temperature. The reducing properties of the solvent are here shown to strongly influence the formation of Pt NPs. Based on the in situ formation of CO adsorbed on the NP surface by solvent oxidation, a model is proposed that accounts for the different growth and stabilization mechanisms as well as re‐dispersion properties of the surfactant‐free NPs in different solvents. Using in situ and ex situ characterizations, it is established that in methanol, a slow nucleation with a limited NP growth is achieved. In ethanol, a fast nucleation followed by continuous and pronounced particle sintering occurs.
PAINT‐ing Fluorenylmethoxycarbonyl (Fmoc)‐Diphenylalanine Hydrogels
Authors: Fuentes Edgar , Boháčová Kamila , Fuentes‐Caparrós Ana M. , Schweins Ralf , Draper Emily R. , Adams Dave J. , Pujals Silvia , Albertazzi Lorenzo
Published: May 2020

Self‐assembly of fluorenylmethoxycarbonyl‐protected diphenylalanine (FmocFF) in water is widely known to produce hydrogels. Typically, confocal microscopy is used to visualize such hydrogels under wet conditions, that is, without freezing or drying. However, key aspects of hydrogels like fiber diameter, network morphology and mesh size are sub‐diffraction limited features and cannot be visualized effectively using this approach. In this work, we show that it is possible to image FmocFF hydrogels by Points Accumulation for Imaging in Nanoscale Topography (PAINT) in native conditions and without direct gel labelling. We demonstrate that the fiber network can be visualized with improved resolution (≈50 nm) both in 2D and 3D. Quantitative information is extracted such as mesh size and fiber diameter. This method can complement the existing characterization tools for hydrogels and provide useful information supporting the design of new materials.
Directed Self‐Organization Ensured Enhancement of Charge Carrier Mobilities in a Star‐Shaped Organic Semiconductor
Authors: Birudula Srikanth , Prabhu Deepak D. , Ghosh Tapan , B. Adara , Das Suresh , Vijayaraghavan Ratheesh K.
Published: May 2020

Controlled self‐organization of organic semiconductor molecules into specifically desired architectures on substrates of interest is one of the most imperative challenges faced in the fabrication of high‐performance organic electronic devices. Herein, we report the self‐organization of a star‐shaped molecule FDT‐8 into a highly favored structure, namely, a vertical stack. Thermal annealing of films of FDT‐8 deposited on PEDOT: PSS coated ITO substrates was observed to assist the organization of the molecules into columnar stacks. A significant enhancement in the hole (≈50‐fold) and the electron (≈13‐fold) carrier mobility was observed in single‐carrier devices upon thermal annealing that could be attributed to the aforementioned self‐organization. The ability of these molecules to spontaneously self‐organize was utilized to fabricate bilayer light‐emitting devices.
Transition from 2D to 3D SBA‐15 by High‐Temperature Fluoride Addition and its Impact on the Surface Reactivity Probed by Isopropanol Conversion
Authors: Lamoth Maximilian , Gries Thomas , Girgsdies Frank , Seitz Friedrich , Hashagen Maike , Rosowski Frank , Schlögl Robert , Frei Elias
Published: May 2020

A systematic variation of the SBA‐15 synthesis conditions and their impact on the structural and chemical characteristics are reported. An incremental alteration of the hydrothermal aging temperature and time was used to induce changes of the highly ordered SBA‐15 structure. Any effects on the total surface area, mesopores size, micropore contributions, and pore connectivity are amplified by a combined incremental increase of the NH4F concentration. Based on changes of the unit‐cell parameter as a function of the mesopore size, and a feature in the low‐angle XRD pattern, useful descriptors for the disorder of the corresponding SBA‐15 are identified. An additional analysis of the Brunauer–Emmett–Teller (BET) surface area and pore size distributions enables investigations of the structural integrity of the material. This systematic approach allows the identification of coherencies between the evolution of physical SBA‐15 properties. The obtained correlations of the surface and structural characteristics allow the discrimination between highly ordered 2D SBA‐15, disordered 3D SBA‐15, and highly nonuniform silica fractions with mainly amorphous character. The fluoride‐induced disintegration of the silica structure under hydrothermal conditions was also verified by TEM. A direct influence of the structural adaption on the chemical properties of the surface was demonstrated by isopropanol conversion and H/D exchange monitored by FTIR analysis as sensitive probes for acid and redox active surface sites.
Chemical Profiling of A‐to‐I RNA Editing Using a Click‐Compatible Phenylacrylamide
Authors: Knutson Steve D. , Korn Megan M. , Johnson Ryan P. , Monteleone Leanna R. , Dailey Deanna M. , Swenson Colin S. , Beal Peter A. , Heemstra Jennifer M.
Published: May 2020

Straightforward methods for detecting adenosine‐to‐inosine (A‐to‐I) RNA editing are key to a better understanding of its regulation, function, and connection with disease. We address this need by developing a novel reagent, N‐(4‐ethynylphenyl)acrylamide (EPhAA), and illustrating its ability to selectively label inosine in RNA. EPhAA is synthesized in a single step, reacts rapidly with inosine, and is “click”‐compatible, enabling flexible attachment of fluorescent probes at editing sites. We first validate EPhAA reactivity and selectivity for inosine in both ribonucleosides and RNA substrates, and then apply our approach to directly monitor in vitro A‐to‐I RNA editing activity using recombinant ADAR enzymes. This method improves upon existing inosine chemical‐labeling techniques and provides a cost‐effective, rapid, and non‐radioactive approach for detecting inosine formation in RNA. We envision this method will improve the study of A‐to‐I editing and enable better characterization of RNA modification patterns in different settings.
Molecular Bismuth Cations: Assessment of Soft Lewis Acidity
Authors: Ramler Jacqueline , Lichtenberg Crispin
Published: May 2020

Three‐coordinate cationic bismuth compounds [Bi(diaryl)(EPMe3)][SbF6] have been isolated and fully characterized (diaryl=[(C6H4)2C2H2]2−, E=S, Se). They represent rare examples of molecular complexes with Bi⋅⋅⋅EPR3 interactions (R=monoanionic substituent). The 31P NMR chemical shift of EPMe3 has been found to be sensitive to the formation of LA⋅⋅⋅EPMe3 Lewis acid/base interactions (LA=Lewis acid). This corresponds to a modification of the Gutmann–Beckett method and reveals information about the hardness/softness of the Lewis acid under investigation. A series of organobismuth compounds, bismuth halides, and cationic bismuth species have been investigated with this approach and compared to traditional group 13 and cationic group 14 Lewis acids. Especially cationic bismuth species have been shown to be potent soft Lewis acids that may prefer Lewis pair formation with a soft (S/Se‐based) rather than a hard (O/N‐based) donor. Analytical techniques applied in this work include (heteronuclear) NMR spectroscopy, single‐crystal X‐ray diffraction analysis, and DFT calculations.
Discrete Ti−O−Ti Complexes: Visible‐Light‐Activated, Homogeneous Alternative to TiO2 Photosensitisers
Authors: Behm Kira , Fazekas Eszter , Paterson Martin J. , Vilela Filipe , McIntosh Ruaraidh D.
Published: May 2020

A series of novel bimetallic TiIV amine bis(phenolate) complexes was synthesised and fully characterised. X‐ray crystallography studies revealed distorted octahedral geometries around the Ti centres with single or double oxo‐bridges connecting the two metals. These robust, air‐ and moisture‐stable complexes were employed as photosensitisers generating singlet oxygen following irradiation with visible light (420 nm) LED module in a commercial flow reactor. All five complexes showed high activity in the photo‐oxygenation of α‐terpinene and achieved complete conversion to ascaridole in four hours at ambient temperature. The excellent selectivity of these photosensitisers towards ascaridole (vs. transformation to p‐cymene) was demonstrated with control experiments using a traditional TiO2 catalyst. Further comparative studies employing the free pro‐ligands as well as a monometallic analogue highlighted the importance of the ‘TiO2‐like’ moiety in the polymetallic catalysts. Computational studies were used to determine the nature of the ligand to metal charge transfer (LMCT) states and singlet–triplet gaps for each complex, the calculated trends in the UV‐vis absorption spectra across the series agreed well with the experimental results.
Unexpected Vulnerability of DPEphos to C−O Activation in the Presence of Nucleophilic Metal Hydrides
Authors: Cybulski Mateusz K. , Beattie Nicholas A. , Macgregor Stuart A. , Mahon Mary F. , Whittlesey Michael K.
Published: May 2020

C−O bond activation of DPEphos occurs upon mild heating in the presence of [Ru(NHC)2(PPh3)2H2] (NHC=N‐heterocyclic carbene) to form phosphinophenolate products. When NHC=IEt2Me2, C−O activation is accompanied by C−N activation of an NHC ligand to yield a coordinated N‐phosphino‐functionalised carbene. DFT calculations define a nucleophilic mechanism in which a hydride ligand attacks the aryl carbon of the DPEphos C−O bond. This is promoted by the strongly donating NHC ligands which render a trans dihydride intermediate featuring highly nucleophilic hydride ligands accessible. C−O bond activation also occurs upon heating cis‐[Ru(DPEphos)2H2]. DFT calculations suggest this reaction is promoted by the steric encumbrance associated with two bulky DPEphos ligands. Our observations that facile degradation of the DPEphos ligand via C−O bond activation is possible under relatively mild reaction conditions has potential ramifications for the use of this ligand in high‐temperature catalysis.
Photo‐switchable Fluorescence in Hydrogen‐Bonded Liquid Crystals
Authors: Kappelt Alexander , Giese Michael
Published: May 2020

A series of hydrogen‐bonded liquid crystals showing switchable fluorescence is reported. The fluorescence behavior results from the unique combination of hydrogen bonding, liquid crystallinity, and photobasicity. Thus, the molecular mobility in the mesophase is essential for the reversible photo‐initiated proton transfer switching on the fluorescence of the assemblies. The application potential of the materials for photo‐patterning was demonstrated.
Binding Site Switch by Dispersion Interactions: Rotational Signatures of Fenchone–Phenol and Fenchone–Benzene Complexes
Authors: Burevschi Ecaterina , Alonso Elena R. , Sanz M. Eugenia
Published: May 2020

Non‐covalent interactions between molecules determine molecular recognition and the outcome of chemical and biological processes. Characterising how non‐covalent interactions influence binding preferences is of crucial importance in advancing our understanding of these events. Here, we analyse the interactions involved in smell and specifically the effect of changing the balance between hydrogen‐bonding and dispersion interactions by examining the complexes of the common odorant fenchone with phenol and benzene, mimics of tyrosine and phenylalanine residues, respectively. Using rotational spectroscopy and quantum chemistry, two isomers of each complex have been identified. Our results show that the increased weight of dispersion interactions in these complexes changes the preferred binding site in fenchone and sets the basis for a better understanding of the effect of different residues in molecular recognition and binding events.
A Mechanistic Study on Reactions of Group 13 Diyls LM with Cp*SbX2: From Stibanyl Radicals to Antimony Hydrides
Authors: Helling Christoph , Wölper Christoph , Cutsail George E. , Haberhauer Gebhard , Schulz Stephan
Published: May 2020

Oxidative addition of Cp*SbX2 (X=Cl, Br, I; Cp*=C5Me5) to group 13 diyls LM (M=Al, Ga, In; L=HC[C(Me)N (Dip)]2, Dip=2,6‐iPr2C6H3) yields elemental antimony (M=Al) or the corresponding stibanylgallanes [L(X)Ga]Sb(X)Cp* (X=Br 1, I 2) and ‐indanes [L(X)In]Sb(X)Cp* (X=Cl 5, Br 6, I 7). 1 and 2 react with a second equivalent of LGa to eliminate decamethyl‐1,1’‐dihydrofulvalene (Cp*2) and form stibanyl radicals [L(X)Ga]2Sb. (X=Br 3, I 4), whereas analogous reactions of 5 and 6 with LIn selectively yield stibanes [L(X)In]2SbH (X=Cl 8, Br 9) by elimination of 1,2,3,4‐tetramethylfulvene. The reactions are proposed to proceed via formation of [L(X)M]2SbCp* as reaction intermediate, which is supported by the isolation of [L(Cl)Ga]2SbCp (11, Cp=C5H5). The reaction mechanism was further studied by computational calculations using two different models. The energy values for the Ga‐ and the In‐substituted model systems showing methyl groups instead of the very bulky Dip units are very similar, and in both cases the same products are expected. Homolytic Sb−C bond cleavage yields van der Waals complexes from the as‐formed radicals ([L(Cl)M]2Sb. and Cp*.), which can be stabilized by hydrogen atom abstraction to give the corresponding hydrides, whereas the direct formation of Sb hydrides starting from [L(Cl)M]2SbCp* via concerted β‐H elimination is unlikely. The consideration of the bulky Dip units reveals that the amount of the steric overload in the intermediate I determines the product formation (radical vs. hydride).
Direct C−H Borylation of Arenes Catalyzed by Saturated Hydride‐Boryl‐Iridium‐POP Complexes: Kinetic Analysis of the Elemental Steps
Authors: Esteruelas Miguel A. , Martínez Antonio , Oliván Montserrat , Oñate Enrique
Published: May 2020

The saturated trihydride IrH3{κ3‐P,O,P‐[xant(PiPr2)2]} (1; xant(PiPr2)2=9,9‐dimethyl‐4,5‐bis(diisopropylphosphino)xanthene) activates the B−H bond of two molecules of pinacolborane (HBpin) to give H2, the hydride‐boryl derivatives IrH2(Bpin){κ3‐P,O,P‐[xant(PiPr2)2]} (2) and IrH(Bpin)2{κ3‐P,O,P‐[xant(PiPr2)2]} (3) in a sequential manner. Complex 3 activates a C−H bond of two molecules of benzene to form PhBpin and regenerates 2 and 1, also in a sequential manner. Thus, complexes 1, 2, and 3 define two cycles for the catalytic direct C−H borylation of arenes with HBpin, which have dihydride 2 as a common intermediate. C−H bond activation of the arenes is the rate‐determining step of both cycles, as the C−H oxidative addition to 3 is faster than to 2. The results from a kinetic study of the reactions of 1 and 2 with HBpin support a cooperative function of the hydride ligands in the B−H bond activation. The addition of the boron atom of the borane to a hydride facilitates the coordination of the B−H bond through the formation of κ1‐ and κ2‐dihydrideborate intermediates.
Reactive Compression Molding Post‐Inverse Vulcanization: A Method to Assemble, Recycle, and Repurpose Sulfur Polymers and Composites
Authors: Lundquist Nicholas A. , Tikoalu Alfrets D. , Worthington Max J. H. , Shapter Ryan , Tonkin Samuel J. , Stojcevski Filip , Mann Maximilian , Gibson Christopher T. , Gascooke Jason R. , Karton Amir , Henderson Luke C. , Esdaile Louisa J. , Chalker Justin M.
Published: May 2020

Inverse vulcanization provides dynamic and responsive materials made from elemental sulfur and unsaturated cross‐linkers. These polymers have been used in a variety of applications such as energy storage, infrared optics, repairable materials, environmental remediation, and precision fertilizers. In spite of these advances, there is a need for methods to recycle and reprocess these polymers. In this study, polymers prepared by inverse vulcanization are shown to undergo reactive compression molding. In this process, the reactive interfaces of sulfur polymers are brought into contact by mechanical compression. Upon heating these molds at relatively low temperatures (≈100 °C), chemical bonding occurs at the polymer interfaces by S−S metathesis. This method of processing is distinct from previous studies on inverse vulcanization because the polymers examined in this study do not form a liquid phase when heated. Neither compression nor heating alone was sufficient to mold these polymers into new architectures, so this is a new concept in the manipulation of sulfur polymers. Additionally, high‐level ab initio calculations revealed that the weakest S−S bond in organic polysulfides decreases linearly in strength from a sulfur rank of 2 to 4, but then remains constant at about 100 kJ mol−1 for higher sulfur rank. This is critical information in engineering these polymers for S−S metathesis. Guided by this insight, polymer repair, recycling, and repurposing into new composites was demonstrated.
Light‐Driven Active Ion Transport
Authors: Yang Jinlei , Liu Pengchao , Li Lianshan , Tang Zhiyong
Published: May 2020

Solar energy can be harvested by biological systems to regulate the directional transport of protons and ions across cells and organelles. Structural and functional bio‐mimic photo‐active ion nanofluidic conductors, usually in the forms of ion channels and ion pumps, have been increasingly applied to realize active ion transport. However, progress in attaining effective light‐driven active transport of ions (protons) has been constrained by the inherent limitations of membrane materials and their chemical and topological structures. Recent advances in the construction of photo‐responsive physical ion pump in all‐solid‐state membranes could potentially lead to new classes of membrane‐based materials for active ion transport. In this concept, the development of the state‐of‐the‐art technologies for manufacturing artificial light‐driven active ion transport systems are presented and discussed, which mainly involves the utilization of solar energy to realize two types of active ion transport, chemically and physically active ion transport. Afterward, we summarize the key factors towards culminating highly effective and selective membranes for active ion transport. To conclude, we highlight the promising application perspectives of this light‐driven active ion transport technique in the field of energy conversion, bio‐interfaces and water treatment.
Pre‐Polymerization Enables Controllable Synthesis of Nanosheet‐Based Porphyrin Polymers towards High‐Performance Li‐Ion Batteries
Authors: Han Zhuolei , Ai Yan , Jiang Xiaolin , You Yuxiu , Wei Facai , Luo Hao , Cui Jing , Bao Qinye , Fu Jianwei , He Qingguo , Liu Shaohua , Cheng Jiangong
Published: May 2020

The precise regulation of nucleation growth and assembly of polymers is still an intriguing goal but an enormous challenge. In this study, we proposed a pre‐polymerization strategy to regulate the assembly and growth of polymers by facilely controlling the concentration of polymerization initiator, and thus obtained two kinds of different nanosheet‐based porphyrin polymer materials using tetrakis‐5,10,15,20‐(4‐aminophenyl) porphyrin (TAPP) as the precursor. Notably, due to the π–π stacking and doping of TAPP during the preparation process, the obtained PTAPP‐nanocube material exhibits a high intrinsic bulk conductivity reaching 1.49×10−4 S m−1. Profiting from the large π‐conjugated structure of porphyrin units, closely stacked layer structure and excellent conductivity, the resultant porphyrin polymers, as electrode materials for lithium ion batteries, deliver high specific capacity (≈650 mAh g−1 at the current density of 100 mA g−1), excellent rate performance and long‐cycle stability, which are among the best reports of porphyrin polymer‐based electrode materials for lithium‐ion batteries, to the best of our knowledge. Therefore, such a pre‐polymerization approach would provide a new insight for the controllable synthesis of polymers towards custom‐made architecture and function.
Carbon Monoxide Coupling Reactions: A New Concept for the Formation of Hexahydroxybenzene
Authors: Rosenthal Uwe
Published: May 2020

For linear and cyclic coupling reactions of CO, among other products, the formation of the hexapotassium salt of hexahydroxybenzene is of particular interesting. The interaction of metallic potassium and CO offers, via the assumed K[OC≡CO]K as the result of several carbon monoxide coupling reactions, the formation of C6(OK)6 among other products. To date, only speculations exist about the reaction pathway for these products, which were first described by Liebig in 1834. A novel concept is suggested here, which consists of the single steps (i) reductive coupling of CO, (ii) formation of dihetero‐metallacyclopentynes (cis‐2,5‐diheterobutatriene as formal ethylenedione O=C=C=O complexes), (iii) formation of its dinuclear 1‐metalla‐2,5‐dioxo‐cyclopentyne complexes by external coordination of the triple bond, (iv) insertion of CO into the M−C bond of the formed metallacyclopropene, and (v) the reductive elimination of C6(OK)6. The novel aspect of this concept is the formation of dihetero‐metallacyclopentynes (in analogy to the well characterized all‐C‐metallacyclopentynes), which have not been considered in the mechanism of reductive CO coupling reactions. It is expected that the presence of transition‐metal impurities would promote the reaction.
An Iterative Divergent Approach to Conjugated Starburst Borane Dendrimers
Authors: Rauch Florian , Endres Peter , Friedrich Alexandra , Sieh Daniel , Hähnel Martin , Krummenacher Ivo , Braunschweig Holger , Finze Maik , Ji Lei , Marder Todd B.
Published: May 2020

Using a new divergent approach, conjugated triarylborane dendrimers were synthesized up to the 2nd generation. The synthetic strategy consists of three steps: 1) functionalization, via iridium catalyzed C−H borylation; 2) activation, via fluorination of the generated boronate ester with K[HF2] or [N(nBu4)][HF2]; and 3) expansion, via reaction of the trifluoroborate salts with aryl Grignard reagents. The concept was also shown to be viable for a convergent approach. All but one of the conjugated borane dendrimers exhibit multiple, distinct and reversible reduction potentials, making them potentially interesting materials for applications in molecular accumulators. Based on their photophysical properties, the 1st generation dendrimers exhibit good conjugation over the whole system. However, the conjugation does not increase further upon expansion to the 2nd generation, but the molar extinction coefficients increase linearly with the number of triarylborane subunits, suggesting a potential application as photonic antennas.
Dynamic PdII/CuIMultimetallic Assemblies as Molecular Models to Study Metal–Metal Cooperation in Sonogashira Coupling
Authors: Rivada‐Wheelaghan Orestes , Comas‐Vives Aleix , Fayzullin Robert R. , Lledós Agustí , Khusnutdinova Julia R.
Published: May 2020

Cooperation between two different metals plays a crucial role in many synergistic catalytic reactions, such as the Sonogashira C−C cross‐coupling reaction, where an interaction between the Pd and Cu centers is proposed in the transmetalation step. Although several heterobimetallic Pd/Cu complexes were proposed as structural models of the active species in Sonogashira coupling, the detailed understanding of the metal–metal cooperation in transmetalation is still lacking in current systems. In this work, we report a stepwise and systematic approach to building heteromultimetallic Pd/Cu assemblies as a tool to study metal–metal cooperativity. We obtained fully characterized Pd/Cu multimetallic assemblies that show reactivity in alkyne activation, formation of catalytically relevant aryl/acetylide species, and C−C elimination, serving as functional models for Sonogashira reaction intermediates. The combined experimental and DFT studies highlight the importance of ligand‐controlled coordination geometry, metal–metal distances and dynamics of the multimetallic assembly for transmetalation step.
Synthesis of a Molecule with Five Different Adjacent Pnictogens
Authors: Ritter Christian , Weigend Florian , von Hänisch Carsten
Published: May 2020

The first molecular compound with all five pnictogens was obtained by a multi‐step reaction. Lithiation of the (bisamido)diazadiarsetidine (tBuNAs)2(tBuNH)2 in aliphatic solvents leads to the dimeric metallated species [(tBuNAs)2(tBuNLi)2]2 (12). Upon reactions with AsCl3, SbCl3 and BiCl3 the polycyclic compounds [(tBuNAs)2(tBuN)2]PnCl (Pn=As (2), Sb (3), Bi (4)) can be obtained. Conversion of 2–4 with [tBu2SbP(tBu)Li(OEt2)]2 leads to the remarkable interpnictogens [(tBuNAs)2(tBuN)2]PnP(tBu)SbtBu2 (Pn=As (5), Sb (6), Bi (7)), whereby 7 is the first example of a molecule containing all five Group 15 elements. The compound with adjacent AsNBiPSb‐chains is surprisingly stable and does not show high sensibility against light as the labile Bi−P bond might suggest.
Productive Syntheses of Privileged Scaffolds Inspired by the Recognition of a Diels–Alder Pattern Common to Three Classes of Natural Products
Authors: Badarau Eduard , Reddy K. Harsha Vardhan , Loudet Aurore , Simon Charles , Trembleau Laurent , Claerhout Stijn , Pair Etienne , Massip Stéphane , Breton Philippe , Lesur Brigitte , Goldstein Solo , Fourquez Jean‐Marie , Henlin Jean Michel , Ghosez Léon
Published: May 2020

Identification of a common Diels–Alder pattern in three classes of bioactive natural products led us to study the synthesis and cycloaddition of a new class of cyclic dienes readily available from β,γ‐unsaturated lactams. A practical and readily scalable route to the parent p‐methoxybenzyl‐protected 6‐ and 7‐membered β,γ‐unsaturated lactams was developed. These were readily transformed into the corresponding O‐silylated dienes, which were reacted with dimethyl and diethyl fumarate to yield stereoselectively highly functionalized bicyclic adducts. These exhibited unexpected and versatile transformations upon acid hydrolysis depending on the nature of the dienophile substituents and the acid catalyst. All reactions have been performed on multigram quantities. These transformations provide a convenient, economical, and easily scalable pathway for the rapid construction of functionally and stereochemically dense privileged scaffolds for the construction of libraries of natural products‐inspired molecules of pharmacological relevance.
RhIII‐Catalyzed C−H Activation of Aryl Hydroxamates for the Synthesis of Isoindolinones
Authors: Shaaban Saad , Davies Caitlin , Merten Christian , Flegel Jana , Otte Felix , Strohmann Carsten , Waldmann Herbert
Published: May 2020

RhIII‐catalyzed C−H functionalization reaction yielding isoindolinones from aryl hydroxamates and ortho‐substituted styrenes is reported. The reaction proceeds smoothly under mild conditions at room temperature, and tolerates a range of functional groups. Experimental and computational investigations support that the high regioselectivity observed for these substrates results from the presence of an ortho‐substituent embedded in the styrene. The resulting isoindolinones are valuable building blocks for the synthesis of bioactive compounds. They provide easy access to the natural‐product‐like compounds, isoindolobenzazepines, in a one‐pot two‐step reaction. Selected isoindolinones inhibited Hedgehog (Hh)‐dependent differentiation of multipotent murine mesenchymal progenitor stem cells into osteoblasts.
Chemical‐Fuel‐Driven Assembly in Macromolecular Science: Recent Advances and Challenges
Authors: Leng ZeJian , Peng Feng , Hao Xiang
Published: May 2020

In the past decade, chemical‐fuel‐driven processes have been integrated with synthetic self‐assembled systems, in which both the formation and properties can be carefully controlled. This strategy can drive systems far away from equilibrium, tailor the lifetime window of transient self‐assembled systems, thus holding promise for future smart, adaptive, self‐regulated, and life‐like systems. By judging whether the building blocks or transient self‐assembled systems participate in the fuel‐to‐waste conversion, the reported systems can be divided into two classes: dissipative self‐assembly and self‐assembly under dissipative conditions. Among these systems, the utilization of macromolecular building blocks to design non‐equilibrium self‐assemblied systems is becoming common. Macromolecular systems capable of dissipating energy with a programmed time domain have found widespread application, and have therefore been an active field of scientific inquiry. This Minireview aims to highlight the recent progress and opportunities of chemical‐fuel‐driven assembly in macromolecules. We envision that chemical‐fuel‐driven approach will play an increasingly important role in polymer science in the near future.
Agronomic performance and cooking quality characteristics for slow‐darkening pinto beans
Authors: Miklas Phillip N. , Osorno Juan M. , Chaves Bernardo , Cichy Karen A.
Published: May 2020

Slow‐darkening (SD) pinto beans (Phaseolus vulgaris L.) possess a desirable new trait, conditioned by the recessive sd gene, that slows seed coat darkening under delayed harvest and under storage. The effect sd may have on performance needs investigation. We examined agronomic performance and cooking quality of SD pinto beans. There were 30 (15 SD and 15 regular darkening [RD]) recombinant inbred lines (RILs) from each of two biparental inbred populations. The 60 RILs were tested across three locations in North Dakota and Washington. In addition, advanced SD and RD pinto breeding lines were tested in trials from 2010 to 2012 and in 2018. Across 2010–2012 trials, the “early generation bred” SD pintos, as a group, had significantly lower emergence, increased lodging, less seed yield, and smaller seed size than the RD group. Conversely, in the 2018 trial, “recently bred” SD pinto breeding lines had competitive agronomic performance to RD lines for seed yield, reduced lodging, and increased emergence. Further research on cooking time is warranted given that SD RILs cooked 20% faster than the RD RILs in one population. Overall, SD pintos exhibited slightly better canning quality than RD pintos. Whether raw or cooked, SD pintos were much lighter in color than RD pintos, emphasizing the need to keep them separated as distinct market classes. Breeders should continue to focus on improving agronomic performance for emergence, lodging, seed yield, seed size, and canning quality of SD pinto beans.
Shock waves in a rotating non‐Maxwellian viscous dusty plasma
Authors: Ehsan Zahida , Abbasi Muhammad M. , Ghosh Samiran , Khan Majid , Ali Muddasir
Published: May 2020

A theoretical model is presented to study the characteristics of dust acoustic shock in a viscous, magnetized, rotating dusty plasma at both fast and slow time scales. By employing the reductive perturbation technique, the non‐linear Zakharov–Kuznetsov–Burger (ZKB) equation is derived for both cases when the dust is inactive and dynamic (fast and slow time scales). Both electrons and ions are considered to follow the kappa/Cairns distribution. It is observed that in both cases, i.e. when dust is in the background and active, viscosity plays a key role in dissipation for the propagation of acoustic shock. Magnetic field and rotation are responsible for the dispersive term. Superthermality is found to affect significantly the formation of the shock wave along with viscous nature of plasma, whereas the dust charge affects the non‐linear coefficient of the ZKB equation. The present investigation may be beneficial to the understanding of the rotating plasma, in particular the experiments being carried
out.
Effects of diet, habitat, and phylogeny on the fecal microbiome of wild African savanna (Loxodonta africana) and forest elephants (L. cyclotis)
Authors: Budd Kris , Gunn Joe C. , Finch Tabitha , Klymus Katy , Sitati Noah , Eggert Lori S.
Published: May 2020

The gut microbiome, or the community of microorganisms inhabiting the digestive tract, is often unique to its symbiont and, in many animal taxa, is highly influenced by host phylogeny and diet. In this study, we characterized the gut microbiome of the African savanna elephant (Loxodonta africana) and the African forest elephant (Loxodonta cyclotis), sister taxa separated by 2.6–5.6 million years of independent evolution. We examined the effect of host phylogeny on microbiome composition. Additionally, we examined the influence of habitat types (forest versus savanna) and diet types (crop‐raiding versus noncrop‐raiding) on the microbiome within L. africana. We found 58 bacterial orders, representing 16 phyla, across all African elephant samples. The most common phyla were Firmicutes, Proteobacteria, and Bacteroidetes. The microbiome of L. africana was dominated by Firmicutes, similar to other hindgut fermenters, while the microbiome of L. cyclotis was dominated by Proteobacteria, similar to more frugivorous species. Alpha diversity did not differ across species, habitat type, or diet, but beta diversity indicated that microbial communities differed significantly among species, diet types, and habitat types. Based on predicted KEGG metabolic pathways, we also found significant differences between species, but not habitat or diet, in amino acid metabolism, energy metabolism, and metabolism of terpenoids and polyketides. Understanding the digestive capabilities of these elephant species could aid in their captive management and ultimately their conservation.
Trait‐based climate vulnerability of native rodents in southwestern Mexico
Authors: Ramírez‐Bautista Arturo , Thorne James H. , Schwartz Mark W. , Williams John N.
Published: May 2020

Aim

Incorporate species’ trait information together with climate projections for associated habitat to assess the potential vulnerability of rodent taxa to climate change.

Location

Oaxaca State, Mexico.

Methods

We used a trait‐based approach together with climate exposure models to evaluate the vulnerability of rodent species to projected climate conditions in the study region. Vulnerability was estimated based on three factors: (a) Level of climatic exposure that species are projected to experience across their current statewide range; (b) inherent species‐specific sensitivity to stochastic events; and (c) species’ capacity to cope with climate change effects. We defined species as inherently sensitive if they had any of the following: restricted geographic distribution in Mexico; narrow altitudinal range; low dispersal ability; or long generation length.

Results

Vulnerability varied depending on the climate change scenario applied. Under the MPI general circulation model and current emissions trends, by 2099, all species evaluated were projected to have some level of threat (vulnerable for at least one factor), with 4 out of 55 species vulnerable for all three factors, 29 for two factors, and 22 for one factor. Six out of ten rodent species endemic to Oaxaca were vulnerable for two or more factors. We found that species with narrow and restricted‐range distributions combined with low adaptive capacity were projected to be particularly vulnerable.

Main conclusions

By including species‐specific trait information in climate exposure assessments, researchers can contextualize and enhance their understanding about how climate change is likely to affect individual taxa in an area of interest. As such, studies like this one provide more relevant threat assessment information than exposure analyses alone and serve as a starting point for considering how climatic changes interact with an array of other variables to affect native species across their range.
Environmental controls on Landsat‐derived phenoregions across an East African megatransect
Authors: Desanker Gloria , Dahlin Kyla M. , Finley Andrew O.
Published: May 2020

Semiarid and savanna‐type (SAST) ecosystems in East Africa have unique plant species compositions and characteristics that make quantifying this biome's seasonality and interannual variability difficult. Phenoregion classification offers a way to use seasonality of vegetation growth to help understand the phenological spatial patterns of complex landscapes. Here, we used Normalized Difference Vegetation Index (NDVI) time series from Landsat 8 to map phenoregions in scenes centered around national parks from Mt. Kenya National Park (Kenya) to Limpopo National Park (Mozambique). We then assessed whether landscape‐scale controls on phenology are consistent across the region or whether they vary across this latitudinal gradient. We compared our phenoregion maps to MODIS Land Cover and geology, and we used multinomial logistic regression to determine the role that elevation, slope, aspect, and geology play in driving phenological differences. The sites' phenoregions showed no unique land cover composition, suggesting that MODIS land cover does not capture the subtle variations identified in phenoregion analysis. Multinomial logistic regression showed that geographic trend (x‐ and y‐directions) was a strong predictor in four of the five landscapes and that, depending on the scene, geology, elevation, or aspect was a strong secondary predictor. Using seasonality of the NDVI time series to generate phenoregions provides different and, in some cases, more ecologically relevant information, compared to vegetation maps that use only land cover from a single season or time period to generate ecoregions. With a significant population of humans and animals that live in and depend on SAST ecosystems, it is important to better understand vegetation processes and factors that affect them as climate change becomes an increasingly pertinent issue in dry systems.
Transition‐Metal‐Free and Site‐Selective Selenylation of Heterocyclic N‐Oxides in Anisole as a Green Solvent
Authors: Lee Suk Hun , Kwon Na Yeon , Lee Ji Yoon , An Won , Jung Young Hoon , Mishra Neeraj Kumar , Ghosh Prithwish , Park Jung Su , Kim In Su
Published: May 2020

Transition‐metal‐free and site‐selective C–H selenylation of heterocyclic N‐oxides with diselenides is described. This method can be also applied for the formation of C2‐sulfenylated and C2‐tellurinated quinoline derivatives. Notably, the simple reaction conditions with the use of anisole as a green solvent have been employed in this coupling reaction. Combined mechanistic investigations elucidate a plausible reaction mechanism of this process. The synthetic transformations demonstrate the utility of the developed method.
Ga‐based microencapsulated phase change material for low‐temperature thermal management applications
Authors: Kashiyama Kohei , Kawaguchi Takahiro , Dong Kaixin , Sakai Hiroki , Sheng Nan , Kurniawan Ade , Nomura Takahiro
Published: May 2020

Gallium is expected to use as a high‐performance phase change material (PCM) for a low‐temperature thermal management. However, high corrosivity of liquid gallium is a serious technical barrier to handle gallium as a PCM. To this end, we report on the development of a Ga‐based microencapsulated PCM (MEPCM) by using a three‐step process. First, Ga is particularized by high‐speed mixing. Second, a GaOOH shell is precipitated on the surface of the Ga particles by chemical treatment. Finally, the GaOOH shell is subjected to an oxidation treatment, after which the shell transforms into a Ga2O3 shell. As the results, MEPCM obtained at the oxidation temperature of 600°C was the only one completely covered with a shell without agglomeration. The MEPCM was composed of a β‐Ga2O3 shell and Ga core with internal voids, whose presence can relieve the pressure on the shell owing to the volume expansion of the core during solidification. The latent heat of the MEPCM was nearly 56% that of the Ga particles. This study demonstrates the first successful microencapsulation of Ga and exhibits the potential of Ga as a new thermal management material.