bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractThree 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

AbstractNumerous 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

AbstractTheranostic 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

AbstractUnderstanding 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

AbstractSelf‐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

AbstractControlled 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

AbstractA 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

AbstractStraightforward 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

AbstractThree‐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

AbstractA 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

AbstractC−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

AbstractA 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

AbstractNon‐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

AbstractOxidative 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

AbstractThe 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

AbstractInverse 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

AbstractSolar 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.