bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sulfur‐Induced Growth of Coordination Polymer Derived‐Straight Carbon Nanotubes on Carbon Nanofiber Network for Zn‐Air Batteries
Authors: Wang Xian , Du Yujing , Chai Lulu , Ding Junyang , Zhong Li , Miao Ting‐Ting , Hu Yue , Qian Jinjie , Huang Shaoming 
Published: March 2021

AbstractLow‐cost heteroatom‐doped carbon nanomaterials have been widely studied for efficient oxygen reduction reaction and energy storage and conversion in metal‐air batteries. A Masson pine twigs‐like 3‐dimensional network construction of carbon nanofibers (CNFs) with abundant straight long Co, N, and S‐doped carbon nanotubes (CNTs) is developed by thermal treatment of Co‐based polymer coated onto polyacrylonitrile nanofiber network together with thiourea at 900 °C, denoted as CNFT‐Co9S8‐900. It is interesting to note that the introduction of a high concentration of sulfur does not lead to the complete toxicity of catalysts, but promotes the axial growth to selectively form straight CNTs instead of curly bamboo‐like CNTs. The highly graphitized in‐situ grown Co, N, S‐doped CNTs and the 3‐dimensional N‐doped CNF network provide both active catalytic sites and highly conductive paths, which are beneficial for oxygen reduction reaction (ORR). Thus, the optimal CNFT‐Co9S8‐900 performs the excellent ORR catalytic activity with a half‐wave potential of 0.84 V and a diffusion‐limited current density of 5.49 mA cm−2. Furthermore, the CNFT‐Co9S8‐900‐based Zn‐air devices also possess a high power density of 136.9 mW cm−2 better than commercial Pt/C.
Photoinduced Electron vs. Concerted Proton Electron Transfer Pathways in SnIV (l‐Tryptophanato)2 Porphyrin Conjugates
Authors: Natali Mirco , Amati Agnese , Demitri Nicola , Iengo Elisabetta 
Published: March 2021

AbstractAromatic amino acids such as l‐tyrosine and l‐tryptophan are deployed in natural systems to mediate electron transfer (ET) reactions. While tyrosine oxidation is always coupled to deprotonation (proton‐coupled electron‐transfer, PCET), both ET‐only and PCET pathways can occur in the case of the tryptophan residue. In the present work, two novel conjugates 1 and 2, based on a SnIV tetraphenylporphyrin and SnIV octaethylporphyrin, respectively, as the chromophore/electron acceptor and l‐tryptophan as electron/proton donor, have been prepared and thoroughly characterized by a combination of different techniques including single crystal X‐ray analysis. The photophysical investigation of 1 and 2 in CH2Cl2 in the presence of pyrrolidine as a base shows that different quenching mechanisms are operating upon visible‐light excitation of the porphyrin component, namely photoinduced electron transfer and concerted proton electron transfer (CPET), depending on the chromophore identity and spin multiplicity of the excited state. The results are compared with those previously described for metal‐mediated analogues featuring SnIV porphyrin chromophores and l‐tyrosine as the redox active amino acid and well illustrate the peculiar role of l‐tryptophan with respect to PCET.
Synthesis and Properties of Partially Saturated Fluorenyl‐Derived [n]Helicenes Featuring an Overcrowded Alkene
Authors: Pallova Lenka , Gauthier Etienne S. , Abella Laura , Jean Marion , Vanthuyne Nicolas , Dorcet Vincent , Vendier Laure , Autschbach Jochen , Crassous Jeanne , Bastin Stéphanie , César Vincent 
Published: March 2021

AbstractThe straightforward, multigram‐scale synthesis of the partially saturated H6‐fluoreno[n]helicenes (n=5 or 7) featuring a central, overcrowded alkene is described. The key cyclization step was based on an intramolecular McMurry reaction from the corresponding 1,5‐diketones. Chiral stationary phase HPLC analysis and isomer separation indicate that each helicenic compound is constituted of three diastereoisomers at room temperature, i. e. the configurationally stable (R,R,P)/(S,S,M) pair of enantiomers and an apparently achiral compound resulting from the rapid interconversion between the (R,S,P) and (S,R,M) enantiomers. The partially saturated H6‐fluoreno[n]helicenes are oxidatively aromatized to give an efficient access to the corresponding fluoreno[n]helicenes. The chiroptical properties (vibrational and electronic circular dichroism) of the chiral, enantiopure compounds have been measured and analyzed by quantum‐chemical calculations, confirming their helicoidal nature.
Synthesis, Structure, and Chiroptical Properties of Indolo‐ and Pyridopyrrolo‐Carbazole‐Based C2‐Symmetric Azahelicenes
Authors: Taniguchi Taisei , Nishii Yuji , Mori Tadashi , Nakayama Ken‐ichi , Miura Masahiro 
Published: March 2021

AbstractTreatment of 11,12‐bis(1,1’‐biphenyl‐3‐yl or 6‐phenylpyridin‐2‐yl)‐substituted 11,12‐dihydro‐indolo[2,3‐a]carbazole with an oxidizing system of Pd(II)/Ag(I) induced effective double dehydrogenative cyclization to afford the corresponding π‐extended azahelicenes. The optical resolutions were readily achieved by a preparative chiral HPLC. It was found that the pyridopyrrolo‐carbazole‐based azahelicene that contains four nitrogen atoms exhibits ca. 6 times larger dissymmetry factors both in circularly dichroism (CD) and circularly polarized luminescence (CPL), |gCD| and |gCPL| values being 1.1×10−2 and 4.4×10−3, respectively, as compared with the parent indolocarbazole‐based azahelicene. Theoretical calculations at the RI‐CC2 level were employed to rationalize the observed enhanced chiroptical responses. The (chir)optical properties of the former helicene was further tuned by a protonation leading to remarkable red‐shift with a considerable enhancement of the |gCPL| value.
A Novel M8L6 Cubic Cage That Binds Tetrapyridyl Porphyrins: Cage and Solvent Effects in Cobalt‐Porphyrin‐Catalyzed Cyclopropanation Reactions
Authors: Mouarrawis Valentinos , Bobylev Eduard O. , de Bruin Bas , Reek Joost N. H. 
Published: March 2021

AbstractConfinement of a catalyst can have a significant impact on catalytic performance and can lead to otherwise difficult to achieve catalyst properties. Herein, we report the design and synthesis of a novel caged catalyst system Co−G@Fe8(Zn−L ⋅ 1)6, which is soluble in both polar and apolar solvents without the necessity of any post‐functionalization. This is a rare example of a metal‐coordination cage able to bind catalytically active porphyrins that is soluble in solvents spanning a wide variety of polarity. This system was used to investigate the combined effects of the solvent and the cage on the catalytic performance in the cobalt catalyzed cyclopropanation of styrene, which involves radical intermediates. Kinetic studies show that DMF has a protective influence on the catalyst, slowing down deactivation of both [Co(TPP)] and Co−G@Fe8(Zn−L ⋅ 1)6, leading to higher TONs in this solvent. Moreover, DFT studies on the [Co(TPP)] catalyst show that the rate determining energy barrier of this radical‐type transformation is not influenced by the coordination of DMF. As such, the increased TONs obtained experimentally stem from the stabilizing effect of DMF and are not due to an intrinsic higher activity caused by axial ligand binding to the cobalt center ([Co(TPP)(L)]). Remarkably, encapsulation of Co−G led to a three times more active catalyst than [Co(TPP)] (TOFini) and a substantially increased TON compared to both [Co(TPP)] and free Co−G. The increased local concentration of the substrates in the hydrophobic cage compared to the bulk explains the observed higher catalytic activities.
Chemical Bonding in Silicon Carbonyl Complexes
Authors: Sergeieva Tetiana , Mandal Debdeep , Andrada Diego M. 
Published: March 2021

AbstractAlthough silylene‐carbonyl complexes are known for decades, only recently isolable examples have been accomplished. In this work, the bonding situation is re‐evaluated to explain the origins of their remarkable stability within the Kohn‐Sham molecular orbital theory framework. It is shown that the chemical bond can be understood as CO interaction with the silylene via a donor‐acceptor interaction: a σ‐donation from the σCO into the empty p‐orbital of silicon, and a π‐back donation from the sp2 lone pair of silicon into the π*CO antibonding orbitals. Notably, it was established that the driving force behind the surprisingly stable Si−CO compounds, however, is another π‐back donation from a perpendicular bonding R−Si σ‐orbital into the π*CO antibonding orbitals. Consequently, the pyramidalization of the central silicon atom cannot be associated with the strength of the π‐back donation, in sharp contrast to the established chemical bonding model. Considering this additional bonding interaction not only shed light on the bonding situation, but is also an indispensable key for broadening the scope of silylene‐carbonyl chemistry.
Lewis Acid‐Catalyzed Diels‐Alder Reactions: Reactivity Trends across the Periodic Table
Authors: Vermeeren Pascal , Tiezza Marco Dalla , van Dongen Michelle , Fernández Israel , Bickelhaupt F. Matthias , Hamlin Trevor A. 
Published: March 2021

AbstractThe catalytic effect of various weakly interacting Lewis acids (LAs) across the periodic table, based on hydrogen (Group 1), pnictogen (Group 15), chalcogen (Group 16), and halogen (Group 17) bonds, on the Diels‐Alder cycloaddition reaction between 1,3‐butadiene and methyl acrylate was studied quantum chemically by using relativistic density functional theory. Weakly interacting LAs accelerate the Diels‐Alder reaction by lowering the reaction barrier up to 3 kcal mol−1 compared to the uncatalyzed reaction. The reaction barriers systematically increase from halogen<hydrogen<chalcogen<pnictogen‐bonded LAs, i. e., the latter have the least catalytic effect. Our detailed activation strain and Kohn‐Sham molecular orbital analyses reveal that these LAs lower the Diels‐Alder reaction barrier by increasing the asynchronicity of the reaction to relieve the otherwise destabilizing Pauli repulsion between the closed‐shell filled π‐orbitals of diene and dienophile. Notably, the reactivity can be further enhanced on going from a Period 3 to a Period 5 LA, as these species amplify the asynchronicity of the Diels‐Alder reaction due to a stronger binding to the dienophile. These findings again demonstrate the generality of the Pauli repulsion‐lowering catalysis concept.
Intertwined Analytical, Experimental and Theoretical Studies on the Formation and Structure of a Copper Dienolate
Authors: Lecachey Baptiste , Palais Laetitia , de Courcy Benoît , Bouauli Samira , Durandetti Muriel , Oulyadi Hassan , Harisson‐Marchand Anne , Maddaluno Jacques , Gérard Hélène , Vrancken Emmanuel , Campagne Jean‐Marc 
Published: March 2021

AbstractThe reaction of a silyl dienolate, a Cu(II) salt and TBAT yielding the corresponding copper dienolate is addressed. A combined NMR and cyclic voltammetry analysis first highlight the role of TBAT in the Cu(II) to Cu(I) reduction and the structure of the precatalytic species. From these first results a second set of NMR and theoretical studies enable the determination of the structure and the mechanism of formation of the copper dienolate catalytic species. Finally, we showed that that the copper catalyst promote the E/Z s‐cis/s‐trans equilibration of the silyl dienolate precursor through a copper dienolate intermediate. All of these results unveil some peculiarities of the catalytic and asymmetric vinylogous Mukaiyama reaction.
Supramolecular Coordination Cages Based on N‐Heterocyclic Carbene‐Gold(I) Ligands and Their Precursors: Self‐Assembly, Structural Transformation and Guest‐Binding Properties
Authors: Shi Wen‐Jie , Liu Dan , Li Xin , Bai Sha , Wang Yao‐Yu , Han Ying‐Feng 
Published: March 2021

AbstractThe incorporation of functional groups into the cavity of discrete supramolecular coordination cages (SCCs) will bring unique functions and applications. Here, three dicarboxylate ligands (H2L1Cl, H2L2Cl and H2L3Cl) containing N‐heterocyclic carbene (NHC) precursors as linkers were introduced to construct SCCs by combining with two C3‐symmertic (CpZr)3(μ3‐O)(μ2‐OH)3 clusters as three‐connect vertices, resulted in a series of rugby‐like V2E3 (V=vertex, E=edge) type homoleptic cages (SCC‐1, SCC‐2 and SCC‐3). However, V4E6‐type tetrahedral cages (SCC‐4 and SCC‐5), incorporating six Au‐NHC moieties, were obtained when the corresponding NHC‐gold(I) functionalized ligands (H2L1Au, H2L2Au) were applied. For the first time, we present a trackable CpZr‐involved cage to cage conversion to generate a heteroleptic V2E3 cage (SCC‐6) from two homoleptic cages (SCC‐2 and SCC‐5) with different geometries of V2E3 and V4E6. The heteroleptic assembly SCC‐6 can also be formed upon a subcomponent displacement strategy. The structural transformation and reassembly processes were detected and monitored by 1H NMR spectroscopy and electrospray‐ionization mass spectrometry. The formation of heteroleptic assembly was further supported by single crystal X‐ray diffraction analysis. Moreover, homoleptic cage SCC‐2 possesses a trigonal bipyramidal cationic cavity allowing the encapsulation of a series of sulfonate anionic guests.
Scaling Up DNA Origami Lattice Assembly
Authors: Xin Yang , Shen Boxuan , Kostiainen Mauri A. , Grundmeier Guido , Castro Mario , Linko Veikko , Keller Adrian 
Published: March 2021

AbstractThe surface‐assisted hierarchical assembly of DNA origami nanostructures is a promising route to fabricate regular nanoscale lattices. In this work, the scalability of this approach is explored and the formation of a homogeneous polycrystalline DNA origami lattice at the mica‐electrolyte interface over a total surface area of 18.75 cm2is demonstrated. The topological analysis of more than 50 individual AFM images recorded at random locations over the sample surface showed only minuscule and random variations in the quality and order of the assembled lattice. The analysis of more than 450 fluorescence microscopy images of a quantum dot‐decorated DNA origami lattice further revealed a very homogeneous surface coverage over cm2areas with only minor boundary effects at the substrate edges. At total DNA costs of € 0.12 per cm2, this large‐scale nanopatterning technique holds great promise for the fabrication of functional surfaces.
Reductive Rearrangement of a 1‐Phospha‐2‐azanorbornene
Authors: Wonneberger Peter , König Nils , Sárosi Menyhárt B. , Hey‐Hawkins Evamarie 
Published: March 2021

AbstractThe reduction of the 1‐phospha‐2‐azanorbornene derivate endo‐1 with lithium aluminium hydride leads to an unprecedented 1‐phosphabicyclo[3.2.1]octa‐2,5‐diene, while a phospholide anion is formed with lithium. The latter can be protonated resulting in formation of an unusual 2H‐phosphole dimer. Furthermore, 3H‐phospholes, previously assumed to have no synthetic relevance as intermediates, were proposed to act as dienophile in the dimerisation of 3,4‐dimethyl‐1‐phenylphosphole at elevated temperatures based on theoretical calculations.
A moderating mediation model of the antecedents of being driven to work: The role of inclusive leaders as change agents
Authors: Fatima Tasneem , Majeed Mehwish , Zulfiqar Ali Shah Syed 
Published: March 2021

AbstractWith support from social exchange theory, the current study tested the mediating role of employee readiness for organizational change between inclusive leadership and driven to work behaviour. Moreover, collective self‐concept has been suggested as a moderating variable in the proposed mediation model. Data for the current study were collected in three‐time lags from employees (N = 215) of Pakistan's service sector. The results revealed that inclusive leadership is positively associated with being driven to work and employee readiness for organizational change mediates this relationship. Further, collective self‐concept moderates the relationship between inclusive leadership and employee readiness for organizational change; and employee readiness for organizational change and being driven to work. This study offers valuable insights into recruitment and retention decisions.
Disrupted eye and head development in rainbow trout with reduced ultraviolet (sws1) opsin expression
Authors: Novales Flamarique Iñigo , Fujihara Ryo , Yazawa Ryosuke , Bolstad Kennedy , Gowen Brent , Yoshizaki Goro 
Published: March 2021

AbstractVisual opsins are proteins expressed by retinal photoreceptors that capture light to begin the process of phototransduction. In vertebrates, the two types of photoreceptors (rods and cones) express one or multiple opsins and are distributed in variable patterns across the retina. Some cones form opsin retinal gradients, as in the mouse, whereas others form more demarcated opsin domains, as in the lattice‐like mosaic retinas of teleost fishes. Reduced rod opsin (rh1) expression in mouse, zebrafish, and African clawed frog results in lack of photoreceptor outer segments (i.e., the cilium that houses the opsins) and, in the case of the mouse, to retinal degeneration. The effects of diminished cone opsin expression have only been studied in the mouse where knockout of the short‐wavelength sensitive 1 (sws1) opsin leads to ventral retinal cones lacking outer segments, but no retinal degeneration. Here we show that, following CRISPR/Cas9 injections that targeted knockout of the sws1 opsin in rainbow trout, fish with diminished sws1 opsin expression exhibited a variety of developmental defects including head and eye malformations, underdeveloped outer retina, mislocalized opsin expression, cone degeneration, and mosaic irregularity. All photoreceptor types were affected even though sws1 is only expressed in the single cones of wild fish. Our results reveal unprecedented developmental defects associated with diminished cone opsin expression and suggest that visual opsin genes are involved in regulatory processes that precede photoreceptor differentiation.
A dual adaptive explicit time integration algorithm for efficiently solving the cardiac monodomain equation
Authors: Mountris Konstantinos A. , Pueyo Esther 
Published: March 2021

AbstractThe monodomain model is widely used in in‐silico cardiology to describe excitation propagation in the myocardium. Frequently, operator splitting is used to decouple the stiff reaction term and the diffusion term in the monodomain model so that they can be solved separately. Commonly, the diffusion term is solved implicitly with a large time step while the reaction term is solved by using an explicit method with adaptive time stepping. In this work, we propose a fully explicit method for the solution of the decoupled monodomain model. In contrast to semi‐implicit methods, fully explicit methods present lower memory footprint and higher scalability. However, such methods are only conditionally stable. We overcome the conditional stability limitation by proposing a dual adaptive explicit method in which adaptive time integration is applied for the solution of both the reaction and diffusion terms. We perform a set of numerical examples where cardiac propagation is simulated under physiological and pathophysiological conditions. Results show that the proposed method presents preserved accuracy and improved computational efficiency as compared to standard operator splitting‐based methods.
Maladaptive metacognitive beliefs mediated the effect of intolerance of uncertainty on depression
Authors: Chen Jing , Tan Youguo , Cheng Xiaotong , Peng Zhenlei , Qin Cheng , Zhou Xinyi , Lu Xingzi , Huang Anqi , Liao Xiaoyuan , Tian Mingyuan , Liang Xuemei , Huang Chaohua , Zhou Jia , Xiang Bo , Liu Kezhi , Lei Wei 
Published: March 2021

AbstractBoth elevated intolerance of uncertainty (IU) and maladaptive metacognitive beliefs (MBs) were associated with depression. However, the relationship between MBs and IU in clinical depression is unclear. The current study aimed to investigate the putative impairment of MBs and IU in major depressive disorder (MDD) and explore the relationship between these two factors with depressive symptoms. Metacognition Questionnaire—30 Items (MCQ‐30), Intolerance of Uncertainty Scale—Short Form (IUS‐12) and clinical rating scales were administered to 53 patients with MDD and 56 healthy controls (HCs). Stepwise regressions were performed to explore independent contributions of MBs and IU on depression. Mediation analysis was used to examine associations among variables. Patients with MDD reported higher IUS‐12 and MCQ‐30 scores than HCs. Stepwise regressions revealed a unique contribution of negative MBs concerning the consequences of not controlling thoughts (MCQ‐NC) on depression symptoms while controlling the effects of age, gender, anxiety symptoms and IU. MCQ‐NC and negative MBs concerning the uncontrollability and danger of negative thinking (MCQ‐NEG) completely mediated the effects of IU on depression and anxiety symptoms. Our results provided clear evidence that maladaptive negative MBs are directly associated with depression symptoms, and mediated the effect of IU on depression and anxiety symptoms, suggesting that IU and MBs influence clinical symptoms in a hierarchical manner.
Singlet Fission in Dideuterated Tetracene and Pentacene
Authors: Zeiser Clemens , Moretti Luca , Reicherter Florian , Bettinger Holger F. , Maiuri Margherita , Cerullo Giulio , Broch Katharina 
Published: March 2021

AbstractThe impact of molecular vibrations on singlet fission, which is the spontaneous fission of a singlet exciton into two triplet excitons, is studied using ultrafast optical spectroscopy for the prototypical singlet fission chromophores tetracene and pentacene. We modify the frequency of intramolecular vibrations by deuteration, without impacting thin film structure and molecular arrangement, and study the resulting changes in exo‐ and endothermic singlet fission rates by comparing the deuterated and parent chromophores. We find that changes in the frequency of the C−C deformation modes of Δω=6 cm−1 and the occurrence of C−D vibrational modes do not lead to significant modifications in the singlet fission time constants. We conclude that the changes in the frequency of phonon modes induced by deuteration are too small to significantly impact the electron–phonon coupling that drives the singlet fission process.
Congenital Deafness and Recent Advances Towards Restoring Hearing Loss
Authors: Renauld Justine M. , Basch Martin L. 
Published: March 2021

AbstractCongenital hearing loss is the most common birth defect, estimated to affect 2‐3 in every 1000 births. Currently there is no cure for hearing loss. Treatment options are limited to hearing aids for mild and moderate cases, and cochlear implants for severe and profound hearing loss. Here we provide a literature overview of the environmental and genetic causes of congenital hearing loss, common animal models and methods used for hearing research, as well as recent advances towards developing therapies to treat congenital deafness. © 2021 The Authors.