bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surfaces modification of methylcellulose: Cobalt nitrate polymer electrolyte by sulfurated hydrogen gas treatment
Authors: Abdullah Omed Gh. , Aziz Bakhtyar K. , Aziz Shujahadeen B. , Suhail Mahdi H. 
Published: June 2018

ABSTRACTThis article discusses the surface modification of methylcellulose:nitrate cobalt [MC:Co(NO3)2] through the sulfurated hydrogen (H2S) gas treatment. Solution cast technique has been used to fabricate MC:Co(NO3)2‐based solid polymer electrolytes. The results achieved for structural, morphological and optical properties indicate that H2S gas treatment is crucial for modification of polymer electrolytes to polymer composites. The morphological appearance revealed that the H2S gas treatment produced cobalt sulfide (CoS) nanoparticles on the surface of the films. The results of X‐ray diffraction indicate the disruption of the crystalline phase of the MC polymer upon addition of various amounts of Co(NO3)2 salt. The optical absorption spectra of the electrolyte samples shifted to higher wavelengths with increasing the cobalt nitrate salt concentration. The optical band gap of MC incorporated with 40 wt % Co(NO3)2 concentration was 4.69 and reduced to 4.52 eV after H2S surface treatment. The linear relationship between the refractive index and salt concentration supports the uniform distribution of the developed nanoparticles appeared in STM images. The significant change in intensity and position of Fourier transform infrared transmittance bands is an evidence for the formation of charge transfer complex between the added salt and the MC host polymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46676.
Functionalized polymeric membrane with aquaporin using click chemistry for water purification application
Authors: He Yuan , Hoi Hiofan , Montemagno Carlo D. , Abraham Sinoj 
Published: June 2018

ABSTRACTA new type of aquaporin‐based biomimetic water purification membrane is fabricated using a propargyl functionalized β‐sheet peptide (FBP1). FBP1 is demonstrated to bind to aquaporin and form a stable protein–peptide complex in aqueous solution, as well as covalently conjugate with azide group. Substrate starting material, polysulfone (PSU), is modified with ∼1.05 azide group per repeating unit and casted into a thin film substrate with appropriate pore size structure using non‐solvent induced phase separation technique. Protein–peptide complex then is clicked onto the substrate using an in‐house built circulating system. The successful immobilization is verified by surface chemical composition analysis and surface morphology analysis. The preliminary salt rejection results show salt rejection improvement from 5% of control membrane to 12.5%. We thus demonstrate a promising method to conjugate a thin layer of membrane protein onto polymeric substrate and well maintain the functionality of membrane proteins. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46678.
Synthesis and glutathione reductase inhibitory properties of 5‐methyl‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one's aryl Schiff base derivatives
Authors: Balaydın Halis Türker , Özil Musa , Şentürk Murat 
Published: June 2018

AbstractGlutathione reductase (GR) is responsible for the existence of the reduced glutathione (GSH) molecule, a crucial antioxidant against oxidative stress reagents. The antimalarial activities of some redox active compounds are attributed to their inhibition of antioxidant flavoenzyme GR, and inhibitors are therefore expected to be useful for the treatment of malaria. In this work, a fast and effective synthesis and the GR inhibitory properties of 5‐methyl‐2,4‐dihydro‐3H‐1,2,4‐triazol‐3‐one's aryl Schiff base derivatives are reported. For this aim, the triazol nucleus was obtained, which was substituted with identical groups: ester, hydrazide, and Schiff base system at the N‐2 and N‐4 nitrogen atoms. The majority of the reactions were carried out by utilizing both microwave and conventional methods in order to compare their yields and reaction times. Beside this, the occuring E/Z geometrical isomers from the CN double bond and the cis/trans amide conformers at the CONH single bond were studied. In the biological activity section of this work, it was found that all synthesized compounds have better inhibitory activity than N,N‐bis(2‐chloroethyl)‐N‐nitrosourea against GR; especially, two molecules, 6e and 6f, are the best among them. The evidence indicates that these Schiff base derivatives, with triazole ring, are strong GR inhibitors and novel antimalaria candidates.
The influence of managerial satisfaction on corporate environmental performance and reputation
Authors: Daddi Tiberio , Iraldo Fabio , Testa Francesco , De Giacomo Maria Rosa 
Published: June 2018

AbstractOrganizational studies have widely debated the relationship between job satisfaction and job performance. Some papers have dealt with managerial satisfaction and businesses' performance adopting agency theory to interpret the results. However, no studies have yet considered the relationship between the satisfaction levels of an environmental manager and corporate environmental performance. This paper thus analyses the role played by the environmental manager's satisfaction in enhancing corporate environmental performance and reputation. The paper uses data from a survey of 412 Eco Management and Audit Scheme registered organizations. The results show a positive relationship between managerial satisfaction and environmental performance, whereas no such positive relationship was found when considering eco‐innovation performance. In addition, the environmental manager's satisfaction has a positive and indirect influence on the corporate environmental reputation. These results contribute to the literature on agency theory and aim to extend the debate between job satisfaction and job performance to the sustainable business field.
Extending the Applicability of Exact Nuclear Overhauser Enhancements to Large Proteins and RNA
Authors: Nichols Parker J. , Born Alexandra , Henen Morkos A. , Strotz Dean , Celestine Chi N. , Güntert Peter , Vögeli Beat 
Published: June 2018

AbstractDistance‐dependent nuclear Overhauser enhancements (NOEs) are one of the most popular and important experimental restraints for calculating NMR structures. Despite this, they are mostly employed as semiquantitative upper distance bounds, and this discards the wealth of information that is encoded in the cross‐relaxation rate constant. Information that is lost includes exact distances between protons and dynamics that occur on the sub‐millisecond timescale. Our recently introduced exact measurement of the NOE (eNOE) requires little additional experimental effort relative to other NMR observables. So far, we have used eNOEs to calculate multistate ensembles of proteins up to approximately 150 residues. Here, we briefly revisit eNOE methodology and present two new directions for the use of eNOEs: applications to large proteins and RNA.
Chromium Complexes with Oxido and Corrolato Ligands: Metal‐Based Redox Processes versus Ligand Non‐Innocence
Authors: Garai Antara , Sobottka Sebastian , Schepper Rahel , Sinha Woormileela , Bauer Matthias , Sarkar Biprajit , Kar Sanjib 
Published: June 2018

AbstractMetal‐ versus ligand‐centered redox processes and the effects of substituents on the ligands on the spectroscopic properties of the metal complexes are at the heart of research on metal complexes with non‐innocent ligands. This work presents three examples of chromium complexes that contain both oxido and corrolato ligands, with the substituents on the corrolato ligands being different in the three cases. Combined X‐ray crystallographic, electrochemical, UV/Vis/NIR/EPR spectroelectrochemical, and EXAFS/XANES measurements, together with DFT calculations, have been used to probe the complexes in three different redox forms. This combined approach makes it possible to address questions related to chromium‐ versus corrolato‐centered redox processes, and the accessibility (or not) of CrIV, CrV, and CrVI in these complexes, as well as their spin states. To the best of our knowledge, these are the first EXAFS/XANES investigations on Cr‐corrolato complexes in different redox forms, and hence these data should set benchmarks for future investigations on such complexes by this method.
Direct Amination of Alcohols Catalyzed by Aluminum Triflate: An Experimental and Computational Study
Authors: Payard Pierre‐Adrien , Gu Qingyi , Guo Wenping , Wang Qianran , Corbet Matthieu , Michel Carine , Sautet Philippe , Grimaud Laurence , Wischert Raphael , Pera‐Titus Marc 
Published: June 2018

AbstractAmong the best‐performing homogeneous catalysts for the direct amination of activated secondary alcohols with electron‐poor amine derivatives, metal triflates, such as aluminum triflate, Al(OTf)3, stand out. Herein we report the extension of this reaction to electron‐rich amines and activated primary alcohols. We provide detailed insight into the structure and reactivity of the catalyst under working conditions in both nitromethane and toluene solvent, through experiment (cyclic voltammetry, conductimetry, NMR spectroscopy), and density functional theory (DFT) simulations. Competition between aniline and benzyl alcohol for Al in the two solvents explains the different reactivities. The catalyst structures predicted from the DFT calculations were validated by the experiments. Whereas a SN1‐type mechanism was found to be active in nitromethane, we propose a SN2 mechanism in toluene to rationalize the much higher selectivity observed when using this solvent. Also, unlike what is commonly assumed in homogeneous catalysis, we show that different active species may be active instead of only one.
Phenothiazine‐Based Oligo(p‐phenylenevinylene)s: Substituents Affected Self‐Assembly, Optical Properties, and Morphology‐Induced Transport
Authors: Arivazhagan C. , Satapathy Sitakanta , Jana Arijit , Malakar Partha , Prasad Edamana , Ghosh Sundargopal 
Published: June 2018

AbstractDesigning intramolecular charge‐transfer (ICT)‐based luminogenic ordered assemblies exhibiting significant electrical transport is a challenging task in the field of organic optoelectronics. In this context, a series of novel phenothiazine‐based oligo(p‐phenylenevinylene) (OPV1‐6) derivatives were designed and their structure–property relationship was investigated. Upon examining their photophysical properties, all the OPVs were found to exhibit significant intramolecular charge‐transfer characteristics in organic solvents. While inspecting the self‐assembly behaviour, the OPV with a long alkyl chain on the central phenyl core (OPV4) underwent gelation in organic solvent mixtures through strong hydrophobic interactions of the long hexadecyl chains and π‐interactions from their aromatic counterparts. Computational studies revealed a lamellar packing of molecules in the assembly. Interestingly, the degree of ICT and the gelation abilities of OPVs were significantly influenced by the electronic nature of the substituents appended to the peripheral phenothiazines. Further, the AC impedance results revealed an increase in storage and electronic transport for the fluorescent thin films prepared by an increase in the content of OPV4 in PMMA.
In Silico Design and Enantioselective Synthesis of Functionalized Monocyclic 3‐Amino‐1‐carboxymethyl‐β‐lactams as Inhibitors of Penicillin‐Binding Proteins of Resistant Bacteria
Authors: Decuyper Lena , Deketelaere Sari , Vanparys Lore , Jukič Marko , Sosič Izidor , Sauvage Eric , Amoroso Ana Maria , Verlaine Olivier , Joris Bernard , Gobec Stanislav , D'hooghe Matthias 
Published: June 2018

AbstractAs a complement to the renowned bicyclic β‐lactam antibiotics, monocyclic analogues provide a breath of fresh air in the battle against resistant bacteria. In that framework, the present study discloses the in silico design and unprecedented ten‐step synthesis of eleven nocardicin‐like enantiomerically pure 2‐{3‐[2‐(2‐aminothiazol‐4‐yl)‐2‐(methoxyimino)acetamido]‐2‐oxoazetidin‐1‐yl}acetic acids starting from serine as a readily accessible precursor. The capability of this novel class of monocyclic 3‐amino‐β‐lactams to inhibit penicillin‐binding proteins (PBPs) of various (resistant) bacteria was assessed, revealing the potential of α‐benzylidenecarboxylates as interesting leads in the pursuit of novel PBP inhibitors. No deactivation by representative enzymes belonging to the four β‐lactamase classes was observed, while weak inhibition of class C β‐lactamase P99 was demonstrated.
Deactivation of Excited States in Transition‐Metal Complexes: Insight from Computational Chemistry
Authors: Sousa Carmen , Alías Marc , Domingo Alex , de Graaf Coen 
Published: June 2018

AbstractInvestigation of the excited‐state decay dynamics of transition‐metal systems is a crucial step for the development of photoswitchable molecular based materials with applications in growing fields as energy conversion, data storage, or molecular devices. The photophysics of these systems is an entangled problem arising from the interplay of electronic and geometrical rearrangements that take place on a short time scale. Several factors play a role in the process: various electronic states of different spin and chemical character are involved, the system undergoes important structural variations and several nonradiative processes can occur. Computational chemistry is a useful tool to get insight into the microscopic description of the photophysics of these materials, since it provides unique information about the character of the electronic spin states involved, the energetics and time evolution of the system. In this review article, we present an overview of the state of the art methodologies available to address the several aspects that have to be incorporated to properly describe the deactivation of excited states in transition‐metal complexes. The most recent developments in theoretical methods are discussed and illustrated with examples.
Benzylic Functionalisation of Phenyl all‐cis‐2,3,5,6‐Tetrafluorocyclohexane Provides Access to New Organofluorine Building Blocks
Authors: Bykova Tetiana , Al‐Maharik Nawaf , Slawin Alexandra M. Z. , Bühl Michael , Lebl Tomas , O'Hagan David 
Published: June 2018

AbstractSelectively fluorinated hydrocarbons continue to attract attention for tuning pharmacokinetic properties in agrochemical and pharmaceutical discovery programmes. This study identifies benzylic bromination of phenyl all‐cis‐2,3,5,6‐tetrafluorocyclohexane 2 as a key reaction for accessing building blocks containing the all‐cis‐2,3,5,6‐tetrafluorocyclohexane ring system. These cyclohexanes are of interest as the fluorines are only on one face of the cyclohexane, and this imparts an unusual polar aspect, very different to an otherwise hydrophobic cyclohexane. Ritter type reactions of benzyl bromide 4 with DMF and acetonitrile generated the corresponding benzyl alcohol 6 and benzylacetamide 7 respectively. Benzylacetamide 7 was hydrolysed to benzyl amine 8 and syn‐amino‐alcohol 9, and separately the phenyl ring was oxidatively cleaved to furnish carboxylic acid acetamide 10, which after hydrolysis gave the tetrafluorocyclohexyl amino acid 11. A trans‐halogenation of benzylbromide 4 with AgF2 gave benzyl fluoride 13. Oxidative cleavage of the aryl ring then gave pentafluorocyclohexyl carboxylic acid 14. This carboxylic acid was readily converted to amides 23–26 and the preferred conformations of these α‐fluoroamides were explored by DFT, X‐ray structure and 1H–19F HOESY NMR analysis.
Donor–Acceptor Complexes between 1,2,5‐Chalcogenadiazoles (Te, Se, S) and the Pseudohalides CN−and XCN−(X=O, S, Se, Te)
Authors: Semenov Nikolay A. , Gorbunov Dmitry E. , Shakhova Margarita V. , Salnikov Georgy E. , Bagryanskaya Irina Y. , Korolev Valery V. , Beckmann Jens , Gritsan Nina P. , Zibarev Andrey V. 
Published: June 2018

AbstractDonor–acceptor (D–A) complexes between 3,4‐dicyano‐1,2,5‐chalcogenadiazoles [chalcogen=Te (1 a), Se (1 b), S (1 c)] and the pseudohalides CN−and XCN−(X=O, S, Se, Te) were studied experimentally and theoretically. For1 a, they were isolated as [K(18‐crown‐6)][1 a‐CN] (2), [K(18‐crown‐6)][1 a‐NCO] (3), [K(18‐crown‐6)][1 a‐SCN] (4), [K(18‐crown‐6)][1 a‐SeCN] (5), and [K][1 a‐NCSe] (6) and characterized by X‐ray diffraction (XRD), UV/Vis and NMR spectroscopy, and DFT and QTAIM calculations. For1 band1 c, the complexes were not isolated due to unfavorable thermodynamics. In all isolated complexes, the D–A bonds, stabilized by negative hyperconjugation, were longer than the sum of the covalent radii and shorter than the sum of the van der Waals radii of the bonded atoms. In mixtures of1 a, F−, and SeCN−, the complex [1 a‐F]−was selectively formed in accordance with thermodynamics. The reaction of1 awith SeCN−and the cyclic trimeric perfluoro‐ortho‐phenylene mercury afforded the complex [K(18‐crown‐6)][SCN]⋅(o‐C6F4Hg)3, which was characterized by XRD.
Hydrogen Bonding of N‐Heterocyclic Carbenes in Solution: Mechanisms of Solvent Reorganization
Authors: Gehrke Sascha , Hollóczki Oldamur 
Published: June 2018

AbstractThe hydrogen‐bond dynamics of N‐heterocyclic carbenes plays a central role in their proton‐transfer reactions, and the effects of hydrogen bonding are also often invoked in corresponding organocatalytic applications. In the present study, the structures and lifetimes of hydrogen bonds have been investigated for several carbenes in alcohol‐containing solutions by classical molecular dynamics simulations. The basicity of the carbene was found to be of major importance; while the least basic carbenes are often in their free form in the solvent, by increasing the basicity the simulations show increased hydrogen bonding, often even with two alcohol molecules at a time. In the latter structure the single lone pair of the carbene is in interplay with two hydrogen bond donors. The exchange mechanism is different for carbenes with different basicities, with different substituents, and in different solvents, occurring through the free carbene for the least basic compounds, and through the aforementioned doubly‐hydrogen‐bonded structure in case of the most basic derivatives. Since this process plays a central role also in H/D exchange reactions, we argue that the pK values calculated from the related measurements have a varying physical meaning for the different carbenes. The lifetimes of the hydrogen bonds are apparently also clearly related to the basicity of the carbene, with gradually increasing lifetimes for the most basic compounds.
Diversity Driven Decoration and Ligation of Fullerene by Ugi and Passerini Multicomponent Reactions
Authors: Ravanello Bruno B. , Seixas Nalin , Rodrigues Oscar E. D. , da Silva Rafael S. , Villetti Marcos A. , Frolov Andrej , Rivera Daniel G. , Westermann Bernhard 
Published: June 2018

AbstractAiming at providing an efficient and versatile method for the diversity‐oriented decoration and ligation of fullerenes, we report the first C60 derivatization strategy based on isocyanide‐multicomponent reactions (I‐MCRs). The approach comprises the use of Passerini and Ugi reactions for assembling pseudo‐peptidic scaffolds (i.e., N‐alkylated and depsipeptides, peptoids) on carboxylic acid‐functionalized fullerenes. The method showed wide substrate scope for the oxo and isocyanide components, albeit the Ugi reaction proved efficient only for aromatic amines. The approach was successfully employed for the ligation of oligopeptides and polyethyleneglycol chains (PEG) to C60, as well as for the construction of bis‐antennary as well as PEG‐tethered dimeric fullerenes. The quantum yields for the formation of 1O2 was remarkable for the selected compounds analyzed.
A Porous Framework as a Variable Chemosensor: From the Response of a Specific Carcinogenic Alkyl‐Aromatic to Selective Detection of Explosive Nitroaromatics
Authors: Xue Hui , Song Danhua , Liu Caiping , Lyu Guangxun , Yuan Daqiang , Jiang Feilong , Chen Qihui , Hong Maochun 
Published: June 2018

AbstractSelective probing of one molecule from one class of similar molecules is highly challenging due to their similar chemical and physical properties. Herein, a novel metal–organic framework FJI‐H15 with flexible porous cages has been designed and synthesized, which can specifically recognize ethylbenzene with ultrahigh enhancement efficiency from a series of alkyl‐aromatics, in which an unusual size‐dependent interaction has been found and proved. It can also selectively detect phenolic‐nitroaromatics among a series of nitroaromatics based on energy transfer and electrostatic interactions. Such unusual specificity and variable mechanisms responding to different types of molecules have not yet been reported, which will provide a new strategy for the development of more effective chemosensors based on MOFs for probing small structural differences in molecules.
Reaction Kinetics Direct a Rational Synthesis of an HIV‐1 Inactivator of Nucleocapsid Protein 7 and Provide Mechanistic Insight into Cellular Metabolism and Antiviral Activity
Authors: Nikolayevskiy Herman , Scerba Michael T. , Deschamps Jeffrey R. , Appella Daniel H. 
Published: June 2018

AbstractInvited for the cover of this issue is the group of Daniel Appella at the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health. The image depicts the critical role of both oxidative and acetylative mechanistic pathways as the thiolate of SAMT‐247 attempts to hold the viral particle at bay. Read the full text of the article at 10.1002/chem.201801253.
Novel Oxidative Ugi Reaction for the Synthesis of Highly Active, Visible‐Light, Imide‐Acridinium Organophotocatalysts
Authors: Gini Andrea , Uygur Mustafa , Rigotti Thomas , Alemán José , García Mancheño Olga 
Published: June 2018

AbstractA newly designed class of acridinium‐based organophotocatalysts bearing an imide group at the C9‐position is presented. To achieve these unprecedented structures, a synthetic strategy based on a novel straightforward oxidative Ugi‐type reaction at the benzylic position of C9‐unsubstituted acridanes was developed. The introduction of the imide‐unit affords a notable photocatalytic activity enhancement, allowing efficient transformations in different oxidative and reductive visible‐light catalytic reactions.
OCT1 Deficiency Affects Hepatocellular Concentrations and Pharmacokinetics of Cycloguanil, the Active Metabolite of the Antimalarial Drug Proguanil
Authors: Matthaei Johannes , Seitz Tina , Jensen Ole , Tann Annabelle , Prukop Thomas , Tadjerpisheh Sina , Brockmöller Jürgen , Tzvetkov Mladen V. 
Published: June 2018

Cycloguanil, the active metabolite of proguanil, acts on malaria schizonts in erythrocytes and hepatocytes. We analyzed the impact of the organic cation transporter OCT1 on hepatocellular uptake and pharmacokinetics of proguanil and cycloguanil. OCT1 transported both proguanil and cycloguanil. Common variants OCT1*3 and OCT1*4 caused a substantial decrease and OCT1*5 and OCT1*6 complete abolishment of proguanil uptake. In 39 healthy subjects, low‐activity variants OCT1*3 and OCT1*4 had only minor effects on proguanil pharmacokinetics. However, both, cycloguanil area under the time‐concentration curve and the cycloguanil‐to‐proguanil ratio were significantly dependent on number of these low‐functional alleles (P = 0.02 for both). Together, CYP2C19, CYP3A5, OCT1 polymorphisms, and sex accounted for 61% of the variation in the cycloguanil‐to‐proguanil ratio. Most importantly, in vitro OCT1 inhibition caused a fivefold decrease of intracellular cycloguanil concentrations in primary human hepatocytes. In conclusion, OCT1‐mediated uptake is a limiting step in bioactivation of proguanil, and OCT1 polymorphisms may affect proguanil efficacy against hepatic malaria schizonts.