bluuebunny/crossref_metadata_2025_split huggingface dataset:
Homogeneous and Gas–Liquid Catellani‐Type Reaction Enabled by Continuous‐Flow Chemistry
Authors: Casnati Alessandra , Gemoets Hannes P. L. , Motti Elena , Della Ca' Nicola , Noël Timothy 
Published: August 2018

AbstractA practical homogeneous and gas‐liquid palladium‐catalyzed Catellani‐type reaction using a continuous‐flow platform is described. The implementation of continuous‐flow technology allowed the acceleration of the transformation and, for the first time, expansion of the chemical space to gaseous olefins (i.e., ethylene, propylene and 3,3,3‐trifluoropropene), thus providing a safe and practical approach to sterically hindered ortho‐disubstituted styrenes and vinyl arenes. The complete control over the stoichiometry of gaseous reagents through flow technology proved essential for directing the selectivity of the Catellani reaction to the desired products.
Synthesis of Heavy Dicyanamide Homologues from Air‐Stable Precursors
Authors: Binder Justin F. , Kosnik Stephanie C. , St Onge P. Blake J. , Macdonald Charles L. B. 
Published: August 2018

AbstractA convenient synthesis of dicyanophosphide and dicyanoarsenide anions is reported. These heavy homologues of the long‐known and fundamentally important dicyanamide anion were formed through the nucleophilic displacement of bis(diphenylphosphino)ethane (dppe) from the pnictogen+ transfer agents [dppePn][BPh4] (Pn=P, As) by exposure to cyanide salts. The protocol requires three synthetic steps from commercially available materials and the [dppePn][BPh4] salts are remarkably temperature, air, and moisture stable. All products have been fully characterized by spectroscopic methods and by single‐crystal X‐ray diffraction, and the electronic structures of the DCPn anions have been assessed computationally.
Homochiral Double Helicates Based on Cyclooctatetrathiophene: Chiral Self‐Sorting with the Intramolecular S⋅⋅⋅N Interaction
Authors: Tian Yu , Wang Guangxia , Ma Zhiying , Xu Li , Wang Hua 
Published: August 2018

AbstractThe design and synthesis of homochiral double helicates are reported that are constructed by means of Ag‐induced supramolecular self‐sorting of saddle‐shaped cyclooctatetrathiophene‐based pyridine ligands (1 and 2). The intramolecular S⋅⋅⋅N interaction ensures that the thiophene and pyridine rings of ligands 1 and 2 are in coplanar and syn‐locked structures. In the presence of Ag+, the racemic ligands 1 and 2 only afforded homochiral double helicates, indicating effective chiral self‐sorting process under the influence of the S⋅⋅⋅N interaction. The X‐ray crystal structure of 12Ag2 reveals a pair of homochiral double helicates (R,R,R,R)‐12Ag2 and (S,S,S,S)‐12Ag2. Furthermore, chiral resolution of racemic ligand 1 was achieved by chiral‐phase HPLC, and the enantiomers and their corresponding enantiopure Ag complexes were characterized.
Mechanistic Analysis and Characterization of Intermediates in the Phosphane‐Catalyzed Oligomerization of Isocyanates
Authors: Helberg Julian , Oe Yohei , Zipse Hendrik 
Published: August 2018

AbstractThe mechanism of the oligomerization of aliphatic isocyanates catalyzed by trialkylphosphanes has been studied through low temperature 31P and 15N NMR spectroscopy combined with computational chemistry. A revised mechanism is proposed that contains several (spiro)cyclic pentacoordinate phosphorous intermediates. Previously reported spectroscopic data of a transient intermediate has been reevaluated and assigned to a cyclic intermediate containing a P−N bond by experiments with 15N‐labeled isocyanate. 13C, 15N, and 31P NMR shifts that support this assignment have been calculated using quantum chemical methods.
Effect of alkaline‐earth metals on synthesis of isobutyraldehyde from methanol and ethanol over Cu‐MeOx/Ti‐SBA‐15 catalysts (Me = Mg, Ca, Sr, Ba)
Authors: Zhang Junfeng , Zhang Meng , Wu Yingquan , Zhang Tao , Han Yizhuo , Tan Yisheng 
Published: August 2018

AbstractCu‐MeO/Ti‐SBA‐15 catalysts (Me = Mg, Ca, Sr, and Ba) were used for isobutyraldehyde (IBA) synthesis from methanol and ethanol and characterized by various techniques including XRD, N2 sorption, CO2‐TPD, XPS, etc. Doping different alkaline‐earth meals (Me = Mg, Ca, Sr, and Ba) to Cu/Ti‐SBA‐15 can significantly affect catalytic performance in IBA synthesis. Based on characterizations, different alkaline‐earth metal doping significantly affects the amount of basic sites and the basic strength of the catalyst surface and their interaction with active Cu and other components. Therefore, the higher activity of the catalyst is closely related to larger amounts of basic sites, stronger basicity, and stronger interaction between Cu and MeO.
Synthesis, Computational Docking Study, and Biological Evaluation of a Library of Heterocyclic Curcuminoids with Remarkable Antitumor Activity
Authors: Laali Kenneth K. , Greves William J. , Zwarycz Angela T. , Correa Smits Sebastian J. , Troendle Frederick J. , Borosky Gabriela L. , Akhtar Sharoon , Manna Alak , Paulus Aneel , Chanan‐Khan Asher , Nukaya Manabu , Kennedy Gregory D. 
Published: August 2018

AbstractIn a continuing search for curcuminoid (CUR) compounds with antitumor activity, a novel series of heterocyclic CUR–BF2 adducts and CUR compounds based on indole, benzothiophene, and benzofuran along with their aryl pyrazoles were synthesized. Computational docking studies were performed to compare binding efficiency to target proteins involved in specific cancers, namely HER2, proteasome, VEGFR, BRAF, and Bcl‐2, versus known inhibitor drugs. The majority presented very good binding affinities, similar to, and even more favorable than those of known inhibitors. The indole‐based CUR–BF2 and CUR compounds and their bis‐thiocyanato derivatives exhibited high anti‐proliferative and apoptotic activity by in vitro bioassays against a panel of 60 cancer cell lines, more specifically against multiple myeloma (MM) cell lines (KMS11, MM1.S, and RPMI‐8226) with significantly lower IC50 values versus healthy PBMC cells; they also exhibited higher anti‐proliferative activity in human colorectal cancer cells (HCT116, HT29, DLD‐1, RKO, SW837, and Caco2) than the parent curcumin, while showing notably lower cytotoxicity in normal colon cells (CCD112CoN and CCD841CoN).
Experimental Characterization of the Binding Affinities between Proapoptotic BH3 Peptides and Antiapoptotic Bcl‐2 Proteins
Authors: Kong Wenna , Zhou Mi , Li Qing , Fan Wenjie , Lin Haixia , Wang Renxiao 
Published: August 2018

AbstractThe Bcl‐2 family proteins are key regulators of the intrinsic apoptotic pathway and are among the validated targets for developing anticancer drugs. Protein–protein interactions between the pro‐ and antiapoptotic members of this family determine mitochondrial outer‐membrane permeabilization. Elucidating such protein–protein interactions in a quantitative way is helpful for network pharmacology studies on the Bcl‐2 family, which, in turn, will provide valuable guidance for developing new anticancer therapies. In this study, the binding affinities of the BH3 peptides derived from eight proapoptotic BH3‐only proteins (i.e., Bid, Bim, Puma, Noxa, Bad, Bmf, Bik, Hrk) against five well‐studied antiapoptotic proteins (i.e., Bcl‐xL, Bcl‐2, Mcl‐1, Bcl‐w, Bfl‐1) in the Bcl‐2 family have been measured. Three different types of binding assay (i.e., surface plasmon resonance, fluorescence polarization, and homogeneous time‐resolved fluorescence) were employed for cross‐validation. The results confirmed that each proapoptotic BH3 peptide exhibited a distinct binding profile against the five antiapoptotic proteins. The binding data obtained herein serve as a fresh update or correction to existing knowledge. It is expected that such binding data will be helpful for building more accurate mathematical network models for depicting the complex protein–protein interactions within the Bcl‐2 family.
Development of Potent Inhibitors of Fatty Acid Amide Hydrolase Useful for the Treatment of Neuropathic Pain
Authors: Brindisi Margherita , Borrelli Giuseppe , Brogi Simone , Grillo Alessandro , Maramai Samuele , Paolino Marco , Benedusi Mascia , Pecorelli Alessandra , Valacchi Giuseppe , Di Cesare Mannelli Lorenzo , Ghelardini Carla , Allarà Marco , Ligresti Alessia , Minetti Patrizia , Campiani Giuseppe , di Marzo Vincenzo , Butini Stefania , Gemma Sandra 
Published: August 2018

AbstractThe unique role of fatty acid amide hydrolase (FAAH) in terminating endocannabinoid (EC) signaling supports its relevance as a therapeutic target. Inhibition of EC metabolizing enzymes elicits indirect agonism of cannabinoid receptors (CBRs) and therapeutic efficacy devoid of psychotropic effects. Based on our previous ligands, and aiming at the discovery of new selective FAAH inhibitors, we developed a series of 12 new compounds characterized by functionalized tricyclic scaffolds. All the developed compounds display negligible activity on monoacylglycerol lipase (MAGL) and CBRs. The most potent FAAH inhibitors of the newly developed series, 6‐oxo‐5,6‐dihydro‐4H‐benzo[f]pyrrolo[1,2‐a][1,4]diazepin‐9‐yl‐6‐phenylhexylcarbamate (5 h) and 4‐oxo‐5,6‐dihydro‐4H‐benzo[f]pyrrolo[1,2‐a][1,4]diazepin‐9‐yl‐(6‐phenylhexyl)carbamate (5 i) (nanomolar FAAH inhibitors, the latter of which also shows micromolar affinity at the CB1R), were selected for further studies. Results of cell‐based studies on a neuroblastoma cell line (IMR32) demonstrated 5 h, 5 i, and our reference compound 3 ([3‐(3‐carbamoylpyrrol‐1‐yl)phenyl] N‐(5‐phenylpentyl)carbamate) to lack any cytotoxic effect, while all three showed the ability to decrease oxidative stress by reducing the expression of the redox‐sensitive transcription factor NF‐κB. Encouraged by these data, these compounds were studied in vivo and were dosed orally in a mouse model of neuropathic pain. At 10 mg kg−1 all the compounds were able to relieve the hypersensitivity induced by oxaliplatin.
Childhood trauma is predictive for clinical staging, alcohol consumption, and emotional symptoms in patients with head and neck cancer
Authors: Sarafim‐Silva Bruna Amélia M. , Duarte Gabrielle D. , Sundefeld Maria Lúcia M. M. , Biasoli Éder Ricardo , Miyahara Glauco I. , Bernabé Daniel Galera 
Published: August 2018

BACKGROUNDTraumatic events in childhood have been associated with the occurrence of anxiety and depression in adulthood. This relation has been investigated in patients with breast cancer; however, it has been little explored in patients with other types of cancer. The objective of this study was to evaluate the occurrence of childhood trauma in patients with head and neck cancer and its association with clinicopathological variables and anxiety and depression levels.METHODSThe study included 110 patients with head and neck squamous cell carcinoma (HNSCC) before they started cancer treatment. Clinicopathological and biobehavioral data were collected from patients' medical records. Anxiety and depression levels were assessed with the Beck Anxiety Inventory and the Beck Depression Inventory, respectively. The Childhood Trauma Questionnaire was used to evaluate the occurrence of traumatic events in childhood.RESULTSOne hundred five patients (95.5%) experienced at least 1 type of childhood trauma. Emotional neglect was the most reported childhood trauma (43.8%), and multiple regression revealed that it was an independent variable for advanced clinical staging (β = 2.15, P = .048) and higher alcohol consumption (β = 2.32, P = .031). Patients with HNSCC who experienced more traumatic events in childhood had an almost 12 times greater chance of increased depression levels during the pretreatment period (β = 11.89; P = .0002). The occurrence of physical child neglect was a predictive factor for increased anxiety levels (β = 4.17, P = 0.029).CONCLUSIONSTraumatic events in childhood are predictive for advanced clinical staging, alcohol consumption, and emotional symptoms in patients with HNSCC, and they should be considered in clinical and psychological intervention strategies during cancer treatment. Cancer 2018;000:000‐000. © 2018 American Cancer Society.
Quantifying the Proteolytic Cleavage of Plasma Membrane Proteins in Living Cells
Authors: Calamai Martino , Pavone Francesco Saverio 
Published: August 2018

AbstractThe standard approach to study the activity of proteases consists of lysing cells and measuring the changes in the fluorescence properties of a synthetic substrate after cleavage in vitro. Here, a general protocol that uses a bi‐fluorescent chimeric construct of a known substrate protein that follows the proteolytic processing in living cells is described. This approach is useful, in particular, to search for pharmacological conditions altering the cleavage rate of a certain protease, or to investigate the biological factors influencing a certain proteolytic mechanism. Three different methods (microscopy, flow cytometry, and spectroscopy) to detect fluorescence changes due to alteration in the processing are described. This approach was originally developed for studying conditions affecting the proteolytic activity of the β‐secretase Bace1 on the amyloid precursor protein APP, but can in principle be applied to investigate any membrane protein undergoing ectodomain shedding by proteolytic cleavage. © 2018 by John Wiley & Sons, Inc.
Silicon photonic networks: Signal loss and power challenges
Authors: Crespo Juan‐Jose , Sánchez José L. , Alfaro‐Cortés Francisco J. 
Published: August 2018

SummaryExascale systems are in need for alternative interconnection technologies. Electrical interconnects are not likely to scale well to a large number of computing nodes in terms of energy efficiency and latency. Silicon photonic networks stand as the main alternative to solve this problem, but are we there yet? In this paper, we exhibit some challenges to be solved for this technology to become a viable solution. Signal loss sources play a critical role in photonic network designs as they restrict the ability to perform data transmission in an effective way.
Arginine Side‐Chain Hydrogen Exchange: Quantifying Arginine Side‐Chain Interactions in Solution
Authors: Mackenzie Harold W. , Hansen D. Flemming 
Published: August 2018

AbstractThe rate with which labile backbone hydrogen atoms in proteins exchange with the solvent has long been used to probe protein interactions in aqueous solutions. Arginine, an essential amino acid found in many interaction interfaces, is capable of an impressive range of interactions via its guanidinium group. The hydrogen exchange rate of the guanidinium hydrogens therefore becomes an important measure to quantify side‐chain interactions. Herein we present an NMR method to quantify the hydrogen exchange rates of arginine side‐chain 1Hϵ protons and thus present a method to gauge the strength of arginine side‐chain interactions. The method employs 13C‐detection and the one‐bond deuterium isotope shift observed for 15Nϵ to generate two exchanging species in 1H2O/2H2O mixtures. An application to the protein T4 Lysozyme is shown, where protection factors calculated from the obtained exchange rates correlate well with the interactions observed in the crystal structure. The methodology presented provides an important step towards characterising interactions of arginine side‐chains in enzymes, in phase separation, and in protein interaction interfaces in general.
Putting the Disulfide Bridge at Risk: How UV‐C Radiation Leads to Ultrafast Rupture of the S‐S Bond
Authors: Larsen Martin A. B. , Skov Anders B. , Clausen Christian M. , Ruddock Jennifer , Stankus Brian , Weber Peter M. , Sølling Theis I. 
Published: August 2018

AbstractWe investigate the ultrafast photoinduced dynamics of the cyclic disulfide 1,2‐dithiane upon 200 nm excitation by time‐resolved photoelectron spectroscopy and show that the S−S bond breaks on an ultrafast time scale. This stands in stark contrast to excitation at longer wavelengths where the initially excited S1 state evolves as the wavepacket is guided towards a conical intersection with S0 by a torsional motion involving a partially broken bond between the sulfur atoms. This process at lower excitation energy allows for efficient (re‐)population of S0, rendering dithiane intact. At 200 nm, in contrast, the excitation leads to a manifold of higher excited states, Sn, that are primarily of Rydberg character. We are able to follow the gradual transition from the initially excited state to the dissociative receiver state in real time. The Rydberg states are intersected by a repulsive valence state that mediates a transition to the repulsive S2 surface. Therefore, we propose that the resulting diradical will eventually break apart on a longer timescale. The findings imply that upon going from UV−B to UV−C light the structural integrity of the disulfide moiety is compromised and proteins irradiated in this range will not be able to reform the initial tertiary structure, leading to loss of function.
High Exchange Rate Complexes of 129Xe with Water‐Soluble Pillar[5]arenes for Adjustable Magnetization Transfer MRI
Authors: Schnurr Matthias , Joseph Roymon , Naugolny‐Keisar Alissa , Kaizerman‐Kane Dana , Bogdanoff Nils , Schuenke Patrick , Cohen Yoram , Schröder Leif 
Published: August 2018

AbstractMacrocyclic host structures for generating transiently bound 129Xe have been used in various ultra‐sensitive NMR and MRI applications for molecular sensing of biochemical analytes. They are based on hyperpolarized nuclei chemical exchange saturation transfer (Hyper‐CEST). Here, we tested a set of water‐soluble pillar[5]arenes with different counterions in order to compare their potential contrast agent abilities with that of cryptophane‐A (CrA), the most widely used host for such purposes. The exchange of Xe with such compounds was found to be sensitive to the type of ions present in solution and can be used for switchable magnetization transfer (MT) contrast that arises from off‐resonant pre‐saturation. We demonstrate that the adjustable MT magnitude depends on the interplay of saturation parameters and found that the optimum MT contrast surpasses the CrA CEST performance at moderate saturation power. Since modification of such water‐soluble pillar[5]arenes is straightforward, these compounds can be considered a promising platform for designing various sensors that may complement the field of Xe HyperCEST‐based biosensing MRI.
Tuning the Biradicaloid Nature of Polycyclic Aromatic Hydrocarbons: The Effect of Graphitic Nitrogen Doping in Zethrenes
Authors: Das Anita , Pinheiro Max , Machado Francisco B. C. , Aquino Adélia J. A. , Lischka Hans 
Published: August 2018

AbstractZethrenes are interesting polycyclic aromatic hydrocarbons (PAHs), which possess unique optoelectronic and magnetic properties because of their singlet open‐shell biradicaloid character, making them promising candidates for application in organic electronics. Tuning their properties is a key task in order to develop efficient compounds for practical use by balancing the desired biradicaloid character against its chemical instability. In this work, high‐level theoretical multireference methods appropriate for the correct description of polyradicaloid systems are used to develop rules for doping of zethrenes by means of nitrogen taking heptazethrene (HZ) as a benchmark example. The results of the quantum chemical calculations have been concentrated on a series of quantitative descriptors such as unpaired densities and singlet‐triplet (S−T) splittings. They clearly indicate different regions in the HZ where N‐doping can either lead to strong enhancement of the biradicaloid character or to strong quenching towards a closed shell state. A wide scale of varying open‐shell character is accessible from the different doping positions. It is shown that the S−T splittings correlate well with the total number of unpaired electrons in the medium range of biradicaloid character. For pronounced biradical character the S−T splitting decays to about zero with a margin of ±0.15 eV. In the opposite closed‐shell limit, much larger S−T splittings of up to 3 eV are computed.
Interpenetrating Polymer Network Microgels in Water: Effect of Composition on the Structural Properties and Electrosteric Interactions
Authors: Micali Norberto , Bertoldo Monica , Buratti Elena , Nigro Valentina , Angelini Roberta , Villari Valentina 
Published: August 2018

AbstractMicrogels of cross‐linked interpenetrating polymer networks (IPNs) are very versatile systems combining the properties of colloids and polymers. Herein we study IPN microgels composed of poly(N‐isopropylacrylamide) and poly(acrylic acid) to understand how weight composition and reactant concentrations affect their structural, conformational and electrosteric properties in water. The results show that it is possible to drive the formation of microgels with the desired properties by adjusting IPN composition and preparation method during the synthesis. During synthesis, the polymerization of acrylic acid triggers the merging among IPNs via covalent linking, giving rise to microgels with larger mass and size, the effect being larger for higher concentration of the reactants. In addition, a close relation between the microgel internal conformation and the colloidal stability is observed, due to the presence of screened groups inside the microgel.
Chemical Modification toward Long Spin Lifetimes in Organic Conjugated Radicals
Authors: Dai Ya‐Zhong , Dong Bo‐Wei , Kao Yi , Wang Zi‐Yuan , Un Hio‐Ieng , Liu Zheng , Lin Zhi‐Jun , Li Liang , Xie Fang‐Bai , Lu Yang , Xu Mei‐Xing , Lei Ting , Sun Yu‐Jie , Wang Jie‐Yu , Gao Song , Jiang Shang‐Da , Pei Jian 
Published: August 2018

AbstractOrganic semiconductors for spin‐based devices require long spin relaxation times. Understanding their spin relaxation mechanisms is critical to organic spintronic devices and applications for quantum information processing. However, reports on the spin relaxation mechanisms of organic conjugated molecules are rare and the research methods are also limited. Herein, we study the molecular design and spin relaxation mechanisms by systematically varying the structure of a conjugated radical. We found that solid‐state relaxation times of organic materials are largely different from that in solution state. We demonstrate that substitution of a lower gyromagnetic ratio nucleus (e. g. D, Cl) on the para‐position of the aryl rings in the triphenylmethyl (TM) radical can significantly improve their coherence times (Tm). Flexible thin films based on such radicals exhibit ultra‐long spin–lattice relaxation times (T1) up to 35.6(6) μs and Tm up to 1.08(4) μs under ambient conditions, which are among the longest values in films. More importantly, using the TM radical derivative (5CM), we observed room‐temperature quantum coherence and Rabi cycles in thin film for the first time, suggesting that organic conjugated radicals have great potentials for spin‐based information processing.
Two‐Photon Absorption Properties and Structures of BODIPY and Its Dyad, Triad and Tetrad
Authors: Yang Jian , Rousselin Yoann , Bucher Léo , Desbois Nicolas , Bolze Frédéric , Xu Hai‐Jun , Gros Claude P. 
Published: August 2018

AbstractA series consisting of a dyad, a triad and a tetrad containing either two, three and four BODIPY units, respectively, has been synthesized and fully characterized and compared to two mono‐BODIPY analogs (used as references). The one‐ and two‐photon photophysical properties have been measured and the X‐ray structures of four of the BODIPY derivatives have been determined. In the 700–900 nm range, the two‐photon absorption (TPA) cross sections range from 30 GM to 160 GM for these compounds.