bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dicyclohepta[ijkl,uvwx]rubicene with Two Pentagons and Two Heptagons as a Stable and Planar Non‐benzenoid Nanographene
Authors: Zhang Xi‐Sha , Huang Yan‐Ying , Zhang Jing , Meng Wei , Peng Qian , Kong Ruirui , Xiao Zhenwei , Liu Jie , Huang Miaofei , Yi Yuanping , Chen Liangliang , Fan Qingrui , Lin Gaobo , Liu Zitong , Zhang Guanxin , Jiang Lang , Zhang Deqing 
Published: December 2019

AbstractPolycyclic aromatic hydrocarbons with hexagons/pentagons or hexagons/heptagons have been intensively investigated in recent years, but those with simultaneous presence of hexagons, pentagons and heptagons remain rare. In this paper, we report dicyclohepta[ijkl,uvwx]rubicene (DHR), a non‐benzenoid isomer of dibenzo[bc,kl]coronene with two pentagons and two heptagons. We developed an efficient and scalable synthetic method for DHR by using Scholl reaction and dehydrogenation. Crystal structure of DHR shows that the benzenoid rings, two pentagons and two heptagons are coplanar. The bond lengths analysis and the ICSS(1)zz and LOL‐π calculations indicate that the incorporation of two formal azulene moieties has an effect on the conjugated structure. The π‐electrons of benzenoid and pentagon rings are more delocalized. Cyclic voltammetry studies indicate that DHR shows multiple oxidation and reduction potentials. Interestingly, DHR exhibits unusual S0 to S2 absorption and abnormal anti‐Kasha S2 to S0 emission. Moreover, crystals of DHR exhibit semiconducting behaviour with hole mobility up to 0.082 cm2 V−1 s−1.
Allosteric Recognition of Homomeric and Heteromeric Pairs of Monosaccharides by a Foldamer Capsule
Authors: Mateus Pedro , Chandramouli Nagula , Mackereth Cameron D. , Kauffmann Brice , Ferrand Yann , Huc Ivan 
Published: December 2019

AbstractThe recognition of either homomeric or heteromeric pairs of pentoses in an aromatic oligoamide double helical foldamer capsule was evidenced by circular dichroism (CD), NMR spectroscopy, and X‐ray crystallography. The cavity of the host was predicted to be large enough to accommodate simultaneously two xylose molecules and to form a 1:2 complex (one container, two saccharides). Solution and solid‐state data revealed the selective recognition of the α‐4C1‐d‐xylopyranose tautomer, which is bound at two identical sites in the foldamer cavity. A step further was achieved by sequestering a heteromeric pair of pentoses, that is, one molecule of α‐4C1‐d‐xylopyranose and one molecule of β‐1C4‐d‐arabinopyranose despite the symmetrical nature of the host and despite the similarity of the guests. Subtle induced‐fit and allosteric effects are responsible for the outstanding selectivities observed.
Identification of the Enzymes Mediating the Maturation of the Seryl‐tRNA Synthetase Inhibitor SB‐217452 during the Biosynthesis of Albomycins
Authors: Ushimaru Richiro , Chen Zhang , Zhao Houyuan , Fan Po‐hsun , Liu Hung‐wen 
Published: December 2019

AbstractAlbomycin δ2 is a sulfur‐containing sideromycin natural product that shows potent antibacterial activity against clinically important pathogens. The l‐serine‐thioheptose dipeptide partial structure, known as SB‐217452, has been found to be the active seryl‐tRNA synthetase inhibitor component of albomycin δ2. Herein, it is demonstrated that AbmF catalyzes condensation between the 6′‐amino‐4′‐thionucleoside with the d‐ribo configuration and seryl‐adenylate supplied by the serine adenylation activity of AbmK. Formation of the dipeptide is followed by C3′‐epimerization to produce SB‐217452 with the d‐xylo configuration, which is catalyzed by the radical S‐adenosyl‐l‐methionine enzyme AbmJ. Gene deletion suggests that AbmC is involved in peptide assembly linking SB‐217452 with the siderophore moiety. This study establishes how the albomycin biosynthetic machinery generates its antimicrobial component SB‐217452.
Redox‐Active Two‐Dimensional Covalent Organic Frameworks (COFs) for Selective Reductive Separation of Valence‐Variable, Redox‐Sensitive and Long‐Lived Radionuclides
Authors: Li Yang , Guo Xinghua , Li Xiaofeng , Zhang Meicheng , Jia Zhimin , Deng Yun , Tian Yin , Li Shoujian , Ma Lijian 
Published: December 2019

AbstractWe report the first example of 2D covalent organic framework nanosheets (Redox‐COF1) for the selective reduction and in situ loading of valence‐variable, redox‐sensitive and long‐lived radionuclides (abbreviated as VRL nuclides). Compared with sorbents based on chemical adsorption and physical adsorption, the redox adsorption mechanism of Redox‐COF1 can effectively reduce the impact of functional group protonation under the usual high‐acidity conditions in chemisorption, and raise the adsorption efficiency from the monotonous capture by pores in physisorption. The adsorption selectivity for UO22+ reaches up to unprecedented ca. 97 % at pH 3, more than for any analogous adsorbing material.
Structural Insight into IAPP‐Derived Amyloid Inhibitors and Their Mechanism of Action
Authors: Niu Zheng , Prade Elke , Malideli Eleni , Hille Kathleen , Jussupow Alexander , Mideksa Yonatan G. , Yan Li‐Mei , Qian Chen , Fleisch Markus , Messias Ana C. , Sarkar Riddhiman , Sattler Michael , Lamb Don C. , Feige Matthias J. , Camilloni Carlo , Kapurniotu Aphrodite , Reif Bernd 
Published: December 2019

AbstractDesigned peptides derived from the islet amyloid polypeptide (IAPP) cross‐amyloid interaction surface with Aβ (termed interaction surface mimics or ISMs) have been shown to be highly potent inhibitors of Aβ amyloid self‐assembly. However, the molecular mechanism of their function is not well understood. Using solution‐state and solid‐state NMR spectroscopy in combination with ensemble‐averaged dynamics simulations and other biophysical methods including TEM, fluorescence spectroscopy and microscopy, and DLS, we characterize ISM structural preferences and interactions. We find that the ISM peptide R3‐GI is highly dynamic, can adopt a β‐like structure, and oligomerizes into colloid‐like assemblies in a process that is reminiscent of liquid–liquid phase separation (LLPS). Our results suggest that such assemblies yield multivalent surfaces for interactions with Aβ40. Sequestration of substrates into these colloid‐like structures provides a mechanistic basis for ISM function and the design of novel potent anti‐amyloid molecules.
A Coordinative Dendrimer Achieves Excellent Efficiency in Cytosolic Protein and Peptide Delivery
Authors: Ren Lanfang , Lv Jia , Wang Hui , Cheng Yiyun 
Published: December 2019

AbstractCytosolic protein delivery is a prerequisite for the development of protein therapeutics that act on intracellular targets. Proteins are generally membrane‐impermeable and thus need a carrier such as a polymer to facilitate their internalization. However, the efficient binding of proteins with different isoelectric points to polymeric carriers is challenging. In this study, we designed a coordinative dendrimer to solve this problem. The dendrimers modified with dipicolylamine/zinc(II) complex were capable of binding proteins through a combination of ionic and coordination interactions. The best polymer efficiently delivered 30 cargo proteins and peptides into the cytosol, while maintaining their bioactivity after intracellular release. The removal or replacement of zinc ions in the polymer with other transition‐metal ions lead to significantly decreased efficiency in cytosolic protein delivery. This study provides a new strategy to develop robust and efficient polymers for cytosolic protein delivery.
Boron‐Induced Electronic‐Structure Reformation of CoP Nanoparticles Drives Enhanced pH‐Universal Hydrogen Evolution
Authors: Cao Erping , Chen Zhimin , Wu Hao , Yu Peng , Wang Ying , Xiao Fei , Chen Shuo , Du Shichao , Xie Ying , Wu Yiqun , Ren Zhiyu 
Published: December 2019

AbstractEven though transition‐metal phosphides (TMPs) have been developed as promising alternatives to Pt catalyst for the hydrogen evolution reaction (HER), further improvement of their performance requires fine regulation of the TMP sites related to their specific electronic structure. Herein, for the first time, boron (B)‐modulated electrocatalytic characteristics in CoP anchored on the carbon nanotubes (B‐CoP/CNT) with impressive HER activities over a wide pH range are reported. The HER performance surpasses commercial Pt/C in both neutral and alkaline media at large current density (>100 mA cm−2). A combined experimental and theoretical study identified that the B dopant could reform the local electronic configuration and atomic arrangement of bonded Co and adjacent P atoms, enhance the electrons’ delocalization capacity of Co atoms for high electrical conductivity, and optimize the free energy of H adsorption and H2 desorption on the active sites for better HER kinetics.
Pd‐Iminocarboxylate Complexes and Their Behavior in Ethylene Polymerization
Authors: Deshmukh Satej S. , Gaikwad Shahaji R. , Gonnade Rajesh G. , Pandole Satish P. , Chikkali Samir H. 
Published: December 2019

AbstractDesigning co‐catalyst‐free late transition metal complexes for ethylene polymerization is a challenging task at the interface of organometallic and polymer chemistry. Herein, a set of new, co‐catalyst‐free, single‐component catalytic systems for ethylene polymerization have been unraveled. Treatment of anthranilic acid with various aldehydes produced four iminocarboxylate ligands (L1–L4) in very good to excellent yield (75–92 %). The existence of 2‐((2‐methoxybenzylidene)amino) benzoic acid (L1) has been unambiguously demonstrated using NMR spectroscopy, MS and single‐crystal X‐ray diffraction. A neutral Pd‐iminocarboxylate complex [{N O}PdMe(L1)] (N O=κ2‐N,O‐ArCHNC6H4CO2 with Ar=2‐MeOC6H4) C1 was prepared by treating stoichiometric amount of L1.Na with palladium precursor. The identity of C1 was confirmed by 1–2D NMR spectroscopy and single‐crystal X‐ray diffraction studies. Along the same lines, palladium complexes C2–C4 were prepared from ligands L2–L4 respectively. In‐situ high‐pressure NMR investigations revealed that these Pd complexes are amenable to ethylene insertion and undergo facile β‐H elimination to produce propylene. These palladium complexes were then evaluated in ethylene polymerization reaction and various reaction parameters were screened. When C1–C4 were exposed to ethylene pressures of 10–50 bar, formation of low‐molecular‐weight polyethylene was observed.
Lithium Molybdate (Li2MoO3)−Sulfur Battery
Authors: Dharmasena Ruchira R. , Martinez‐Garcia Alejandro , Atla Veerendra , Akram Muhammad Z. , Sumanasekera Gamini U. , Sunkara Mahendra K. 
Published: December 2019

AbstractHere, we present a lithiated molybdate‐sulfur battery with practical energy density greater than 300 Wh kg−1. Electrochemically pre‐lithiated α‐MoO3 is prepared to form lithium molybdate anode which was tested against mesoporous titania coated sulfur cathode. A pouch cell with a capacity of 5 mAh made using pre‐lithiated lithium molybdate nanowires as anode and mesoporous TiO2 (titania) coated carbon‐sulfur cathode exhibited 1.4 V operating voltage and exhibited 620 Wh kg−1 capacity in the first cycle, dropped to ∼400 Wh kg−1 in 2nd cycle and 300 Wh kg−1 at 100th cycle. Various prelithiation studies indicate that electrochemical lithiation of MoO3 nanomaterials is crucial to make Li2MoO3 material suitable as anode. In situ electrochemical lithiation of MoO3 anode is introduced as a method to fabricate lithium molybdate (Li2MoO3)‐sulfur pouch cells in one step.
The central nucleus of the amygdala lesion attenuates orthodontic pain during experimental tooth movement in rats
Authors: Qiao Hu , Gao Yunan , Huang Qianqian , Jia Ru 
Published: December 2019

AbstractIntroductionOrthodontic pain is the most common adverse side effect reported in the context of tooth movement. Given its central role in processing pain and negative emotion, the central nucleus of the amygdala (CeA) is thought to be a key site involved in orthodontic pain sensation.MethodsIn the present study, we therefore explored whether the CeA is involved in contributing to orthodontic pain in a rat model of tooth movement. For this study, we utilized adult male rats with bilateral sham or electrolytic CeA lesions (400 μA; 25 s), and then we analyzed face grooming behavior as a measure of pain sensation.ResultsThrough this approach, we found that there were time‐ and force‐dependent factors influencing pain levels in these rats. We further found that bilateral CeA lesions markedly reduced tooth movement‐induced orofacial pain and that unilateral CeA lesions did so to a lesser extent.ConclusionsAs such, these results suggest the CeA is a key area of orthodontic pain, with the results of this study highlighting potential avenues for achieving pain relief in those suffering from orthodontic pain.
Biguanides in combination with olaparib limits tumorigenesis of drug‐resistant ovarian cancer cells through inhibition of Snail
Authors: Wang Qiong , López‐Ozuna Vanessa M. , Baloch Tahira , Bithras Joanne , Amin Oreekha , Kessous Roy , Kogan Liron , Laskov Ido , Yasmeen Amber 
Published: December 2019

AbstractOvarian cancer is the most lethal gynecological malignancy. Currently, new chemotherapeutic strategies are required to improve patient outcome and survival. Biguanides, classic anti‐diabetic drugs, have gained importance for theiri antitumor potency demonstrated by various studies. Olaparib is a PARP inhibitor approved for maintenance therapy following platinum‐based chemotherapy. Furthermore, Snai1, a transcription factor that works as a master regulator of the epithelial/mesenchymal transition process (EMT) is involved in ovarian cancer resistance and progression. Here we aimed to demonstrate the possible cross talk between biguanides and Snail in response to olaparib combination therapy. In this study, we have shown that while in A2780CR cells biguanides reduced cell survival (single treatments ~20%; combined treatment ~44%) and cell migration (single treatments ~45%; biguanide‐olaparib ~80%) significantly, A2780PAR exhibited superior efficacy with single (~60%) and combined treatments (~80%). Moreover, our results indicate that knock‐down of Snail further enhances the attenuation of migration, inhibits EMT related‐proteins (~90%) and induces a synergistic effect in biguanide‐olaparib treatment. Altogether, this work suggests a novel treatment strategy against drug‐resistant or recurrent ovarian cancer.
Quinoline Based Monocarbonyl Curcumin Analogs as Potential Antifungal and Antioxidant Agents: Synthesis, Bioevaluation and Molecular Docking Study
Authors: Nagargoje Amol A. , Akolkar Satish V. , Siddiqui Madiha M. , Subhedar Dnyaneshwar D. , Sangshetti Jaiprakash N. , Khedkar Vijay M. , Shingate Bapurao B. 
Published: December 2019

AbstractIn search for new fungicidal and free radical scavenging agents, we synthesized a focused library of 2‐chloroquinoline based monocarbonyl analogs of curcumin (MACs). The synthesized MACs were evaluated for in vitro antifungal and antioxidant activity. The antifungal activity was evaluated against five different fungal strains such as Candida albicans, Fusarium oxysporum, Aspergillus flavus, Aspergillus niger, and Cryptococcus neoformans, respectively. Most of the synthesized MACs displayed promising antifungal activity compared to the standard drug Miconazole. Furthermore, molecular docking study on a crucial fungal enzyme sterol 14α‐demethylase (CYP51) could provide insight into the plausible mechanism of antifungal activity. MACs were also screened for in vitro radical scavenging activity using butylated hydroxytoluene (BHT) as a standard. Almost all MACs exhibited better antioxidant activity compared to BHT.
Role of Post‐translational Modifications in Alzheimer's Disease
Authors: Ramesh Madhu , Gopinath Pushparathinam , Govindaraju Thimmaiah 
Published: December 2019

AbstractThe global burden of Alzheimer's disease (AD) is growing. Valiant efforts to develop clinical candidates for treatment have continuously met with failure. Currently available palliative treatments are temporary and there is a constant need to search for reliable disease pathways, biomarkers and drug targets for developing diagnostic and therapeutic tools to address the unmet medical needs of AD. Challenges in drug‐discovery efforts raise further questions about the strategies of current conventional diagnosis; drug design; and understanding of disease pathways, biomarkers and targets. In this context, post‐translational modifications (PTMs) regulate protein trafficking, function and degradation, and their in‐depth study plays a significant role in the identification of novel biomarkers and drug targets. Aberrant PTMs of disease‐relevant proteins could trigger pathological pathways, leading to disease progression. Advancements in proteomics enable the generation of patterns or signatures of such modifications, and thus, provide a versatile platform to develop biomarkers based on PTMs. In addition, understanding and targeting the aberrant PTMs of various proteins provide viable avenues for addressing AD drug‐discovery challenges. This review highlights numerous PTMs of proteins relevant to AD and provides an overview of their adverse effects on the protein structure, function and aggregation propensity that contribute to the disease pathology. A critical discussion offers suggestions of methods to develop PTM signatures and interfere with aberrant PTMs to develop viable diagnostic and therapeutic interventions in AD.
Azido‐Desferrioxamine Siderophores as Functional Click‐Chemistry Probes Generated in Culture upon Adding a Diazo‐Transfer Reagent
Authors: Gotsbacher Michael P. , Codd Rachel 
Published: December 2019

AbstractThis work aimed to undertake the in situ conversion of the terminal amine groups of bacterial desferrioxamine (DFO) siderophores, including desferrioxamine B (DFOB), to azide groups to enable downstream click chemistry. Initial studies trialed a precursor‐directed biosynthesis (PDB) approach. Supplementing Streptomyces pilosus culture with blunt‐end azido/amine non‐native substrates designed to replace 1,5‐diaminopentane as the native diamine substrate in the terminal amine position of DFOB did not produce azido‐DFOB. Addition of the diazo‐transfer reagent imidazole‐1‐sulfonyl azide hydrogen sulfate to spent S. pilosus medium that had been cultured in the presence of 1,4‐diaminobutane, as a viable native substrate to expand the suite of native DFO‐type siderophores, successfully generated the cognate suite of azido‐DFO analogues. CuI‐mediated or strain‐promoted CuI‐free click chemistry reactions between this minimally processed mixture and the appropriate alkyne‐bearing biotin reagents produced the cognate suite of 1,4‐disubstituted triazole‐linked DFO‐biotin compounds as potential molecular probes, detected as FeIII‐loaded species. The amine‐to‐azide transformation of amine‐bearing natural products in complex mixtures by the direct addition of a diazo‐transfer reagent to deliver functional click chemistry reagents adds to the toolbox for chemical proteomics, chemical biology, and drug discovery.
Characterization of Metal‐zeolite Composite Catalysts: Determining the Environment of the Active Phase
Authors: Juneau Mitchell , Liu Renjie , Peng Yikang , Malge Akhilesh , Ma Zhiqiang , Porosoff Marc D. 
Published: December 2019

AbstractMetal‐zeolite composite catalysts are attracting increased attention due to their unique multifunctional properties. However, it is challenging to identify the physicochemical environment of the active phase, which is essential to improve our understanding of the structure‐performance relationships of such complex catalysts. In this work, commonly available analytical techniques (FTIR, TEM, XRD, etc.) and state‐of‐the‐art user instrumentation (XAS, SANS, e‐TEM, etc.) are reviewed with respect to their applications at different stages of the catalyst lifetime, from early nucleation, to the reaction mechanism and deactivation. Each technique is discussed in detail with examples to provide suggestions and guidelines for choosing the characterization technique(s) that are most appropriate for determining the desired structure‐property relationships of metal‐zeolite composite catalysts. Understanding the most appropriate applications of characterization techniques promotes development of novel synthesis methodologies, and in turn, applications for designing active, selective and stable multifunctional metal‐zeolite composite catalysts.
Manganese Catalyzed Acceptorless Dehydrogenative Coupling Reactions
Authors: Waiba Satyadeep , Maji Biplab 
Published: December 2019

AbstractAcceptorless dehydrogenative coupling (ADC) has emerged as a powerful tool in the chemists’ arsenal for the construction of various carbon‐carbon and carbon‐heteroatom bonds. These protocols are highly atom economical and environmentally benign as they do not require pre‐functionalized starting material and produce only dihydrogen (and water) as the by‐product. This technique, coupled with Earths’ abundant and less toxic manganese catalysis, can prove to be a vital strategy for the generation of molecular complexity from simple starting materials. Manganese catalyzed DHC has been of growing interest, and various low‐ and high‐valent manganese catalysts have been developed. These catalysts were demonstrated to show excellent catalytic activity for the formation of carbon‐carbon, carbon‐heteroatom bonds, and cascade reactions. In this mini‐review, we would like to highlight the recent progress that has been made in manganese catalyzed ADC reactions.
Solid‐State Hybrid Supercapacitor Assembled from a Heterostructured Co−Ni Battery‐like Cathode and Supercapacitor‐Type Highly Disordered Carbon Nanosheets
Authors: Li Zhan , Ma Kongjun , Mi Hongyu , Ji Chenchen , Li Zhiwei , Guo Fengjiao , He Shixue , Wang Conghui , Xu Mengjiao , Pang Huan 
Published: December 2019

AbstractHybrid at either the mechanism or the device level can lead to a hybridization effect of the kinetics and electrochemical characteristic of a supercapacitor (SC). Herein, a heterostructured NiCo2S4/CoxNi1‐x(OH)2 battery‐like cathode material was designed, with which the obtained sample accomplished the combination of excellent electronic and ionic conductivity so as to realize an enhanced faradaic redox storage process. Besides, a SC‐type highly capacitive anode material of a N and S co‐doped porous carbon nanosheets (ACNS) was also fabricated, which exhibits great advantages in terms of its enlarged specific surface area, the ease of introducing pseudocapacitive reactions, and its physical structure. These features directly lead to significant improvements in the electric double‐layer capacitor (EDLC)‐type electrochemical properties of the carbon anode. The combination of an EDLC‐type carbon anode with the redox‐reaction‐type cathode in a full cell device could potentially lead to a charge storage process that simultaneously integrates the electrophysical and electrochemical processes. For these reasons, the obtained solid‐state hybrid SC delivers a wide voltage window of 1.6 V, a high specific capacity of 121.3 C g−1, and enhanced energy/power densities of 26.1 Wh kg−1/11 kW kg−1. The as‐assembled device can maintain a high and stable capacity retention of 89.1 % for over 10 000 cycles. The developed hybrid assembly strategy and the electrode combination may provide design guidelines for designing other high‐energy hybrid SCs.