bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Theoretical Investigation into the Luminescent Properties of d8‐Transition‐Metal Complexes with Tetradentate Schiff Base Ligands
Authors: Tong Glenna So Ming , Chow Pui Keong , To Wai‐Pong , Kwok Wai‐Ming , Che Chi‐Ming 
Published: April 2014

AbstractA theoretical investigation on the luminescence efficiency of a series of d8 transition‐metal Schiff base complexes was undertaken. The aim was to understand the different photophysics of [M‐salen]n complexes (salen=N,N′‐bis(salicylidene)ethylenediamine; M=Pt, Pd (n=0); Au (n=+1)) in acetonitrile solutions at room temperature: [Pt‐salen] is phosphorescent and [Au‐salen]+ is fluorescent, but [Pd‐salen] is nonemissive. Based on the calculation results, it was proposed that incorporation of electron‐withdrawing groups at the 4‐position of the Schiff base ligand should widen the 3MLCT–3MC gap (MLCT=metal‐to‐ligand charge transfer and MC=metal centered, that is, the dd excited state); thus permitting phosphorescence of the corresponding PdII Schiff base complex. Although it is experimentally proven that [Pd‐salph‐4E] (salph=N,N′‐bis(salicylidene)‐1,2‐phenylenediamine; 4E means an electron‐withdrawing substituent at the 4‐position of the salicylidene) displays triplet emission, its quantum yield is low at room temperature. The corresponding PtII Schiff base complex, [Pt‐salph‐4E], is also much less emissive than the unsubstituted analogue, [Pt‐salph]. Thus, a detailed theoretical analysis of how the substituent and central metal affected the photophysics of [M‐salph‐X] (X is a substituent on the salph ligand, M=Pt or Pd) was performed. Temperature effects were also investigated. The simple energy gap law underestimated the nonradiative decay rates and was insufficient to account for the temperature dependence of the nonradiative decay rates of the complexes studied herein. On the other hand, the present analysis demonstrates that inclusions of low‐frequency modes and the associated frequency shifts are decisive in providing better quantitative estimates of the nonradiative decay rates and the experimentally observed temperature effects. Moreover, spin–orbit coupling, which is often considered only in the context of radiative decay rate, has a significant role in determining the nonradiative rate as well.
Metal–Ligand Cooperation on a Diruthenium Platform: Selective Imine Formation through Acceptorless Dehydrogenative Coupling of Alcohols with Amines
Authors: Saha Biswajit , Wahidur Rahaman S. M. , Daw Prosenjit , Sengupta Gargi , Bera Jitendra K. 
Published: April 2014

AbstractMetalmetal singly‐bonded diruthenium complexes, bridged by naphthyridine‐functionalized N‐heterocyclic carbene (NHC) ligands featuring a hydroxy appendage on the naphthyridine unit, are obtained in a single‐pot reaction of [Ru2(CH3COO)2(CO)4] with 1‐benzyl‐3‐(5,7‐dimethyl‐1,8‐naphthyrid‐2‐yl)imidazolium bromide (BIN⋅HBr) or 1‐isopropyl‐3‐(5,7‐dimethyl‐1,8‐naphthyrid‐2‐yl)imidazolium bromide (PIN⋅HBr), TlBF4, and substituted benzaldehyde containing an electron‐withdrawing group. The modified NHC‐naphthyridine‐hydroxy ligand spans the diruthenium unit in which the NHC carbon and hydroxy oxygen occupy the axial sites. All the synthesized compounds catalyze acceptorless dehydrogenation of alcohols to the corresponding aldehydes in the presence of a catalytic amount of weak base 1,4‐diazabicyclo[2.2.2]octane (DABCO). Further, acceptorless dehydrogenative coupling (ADHC) of the alcohol with amines affords the corresponding imine as the sole product. The substrate scope is examined with 1 (BIN, p‐nitrobenzaldehyde). A similar complex [Ru2(CO)4(CH3COO)(3‐PhBIN)][Br], that is devoid of a hydroxy arm, is significantly less effective for the same reaction. Neutral complex 1 a, obtained by deprotonation of the hydroxy arm in 1, is found to be active for the ADHC of alcohols and amines under base‐free conditions. A combination of control experiments, deuterium labeling, kinetic Hammett studies, and DFT calculations support metal–hydroxyl/hydroxide and metal–metal cooperation for alcohol activation and dehydrogenation. The bridging acetate plays a crucial role in allowing β‐hydride elimination to occur. The ligand architecture on the diruthenium core causes rapid aldehyde extrusion from the metal coordination sphere, which is responsible for exclusive imine formation.
Molecular Engineering of Simple Phenothiazine‐Based Dyes To Modulate Dye Aggregation, Charge Recombination, and Dye Regeneration in Highly Efficient Dye‐Sensitized Solar Cells
Authors: Hua Yong , Chang Shuai , He Jian , Zhang Caishun , Zhao Jianzhang , Chen Tao , Wong Wai‐Yeung , Wong Wai‐Kwok , Zhu Xunjin 
Published: April 2014

AbstractA series of simple phenothiazine‐based dyes, namely, TP, EP, TTP, ETP, and EEP have been developed, in which the thiophene (T), ethylenedioxythiophene (E), their dimers, and mixtures are present to modulate dye aggregation, charge recombination, and dye regeneration for highly efficient dye‐sensitized solar cell (DSSC) applications. Devices sensitized by the dyes TP and TTP display high power conversion efficiencies (PCEs) of 8.07 (Jsc=15.2 mA cm−2, Voc=0.783 V, fill factor (FF)=0.679) and 7.87 % (Jsc=16.1 mA cm−2, Voc=0.717 V, FF=0.681), respectively; these were measured under simulated AM 1.5 sunlight in conjunction with the I−/I3− redox couple. By replacing the T group with the E unit, EP‐based DSSCs had a slightly lower PCE of 7.98 % with a higher short‐circuit photocurrent (Jsc) of 16.7 mA cm−2. The dye ETP, with a mixture of E and T, had an even lower PCE of 5.62 %. Specifically, the cell based on the dye EEP, with a dimer of E, had inferior Jsc and Voc values and corresponded to the lowest PCE of 2.24 %. The results indicate that the photovoltaic performance can be finely modulated through structural engineering of the dyes. The selection of T analogues as donors can not only modulate light absorption and energy levels, but also have an impact on dye aggregation and interfacial charge recombination of electrons at the interface of titania, electrolytes, and/or oxidized dye molecules; this was demonstrated through DFT calculations, electrochemical impedance analysis, and transient photovoltage studies.
Two‐Step Functionalization of Oligosaccharides Using Glycosyl Iodide and Trimethylene Oxide and Its Applications to Multivalent Glycoconjugates
Authors: Hsieh Hsiao‐Wu , Davis Ryan A. , Hoch Jessica A. , Gervay‐Hague Jacquelyn 
Published: April 2014

AbstractOligosaccharide conjugates, such as glycoproteins and glycolipids, are potential chemotherapeutics and also serve as useful tools for understanding the biological roles of carbohydrates. With many modern isolation and synthetic technologies providing access to a wide variety of free sugars, there is increasing need for general methodologies for carbohydrate functionalization. Herein, we report a two‐step methodology for the conjugation of per‐O‐acetylated oligosaccharides to functionalized linkers that can be used for various displays. Oligosaccharides obtained from both synthetic and commercial sources were converted to glycosyl iodides and activated with I2 to form reactive donors that were subsequently trapped with trimethylene oxide to form iodopropyl conjugates in a single step. The terminal iodide served as a chemical handle for further modification. Conversion into the corresponding azide followed by copper‐catalyzed azide–alkyne cycloaddition afforded multivalent glycoconjugates of Gb3 for further investigation as anti‐cancer therapeutics.
Expedient Iron‐Catalyzed Coupling of Alkyl, Benzyl and Allyl Halides with Arylboronic Esters
Authors: Bedford Robin B. , Brenner Peter B. , Carter Emma , Carvell Thomas W. , Cogswell Paul M. , Gallagher Timothy , Harvey Jeremy N. , Murphy Damien M. , Neeve Emily C. , Nunn Joshua , Pye Dominic R. 
Published: April 2014

AbstractWhile attractive, the iron‐catalyzed coupling of arylboron reagents with alkyl halides typically requires expensive or synthetically challenging diphosphine ligands. Herein, we show that primary and secondary alkyl bromides and chlorides, as well as benzyl and allyl halides, can be coupled with arylboronic esters, activated with alkyllithium reagents, by using very simple iron‐based catalysts. The catalysts used were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)3] with no added co‐ ligands. In the former case, preliminary mechanistic studies highlight the likely involvement of iron(I)–phosphine intermediates.
Unfolding and Conformational Variations of Thrombin‐Binding DNA Aptamers: Synthesis, Circular Dichroism and Molecular Dynamics Simulations
Authors: Sun Lidan , Jin Hongwei , Zhao Xiaoyang , Liu Zhenming , Guan Yifu , Yang Zhenjun , Zhang Liangren , Zhang Lihe 
Published: April 2014

AbstractThrombin‐binding DNA aptamer (TBA), with a consensus 15‐base sequence: d(GGTTGGTGTGGTTGG), can fold into an antiparallel unimolecular G‐quadruplex structure that is necessary for its interaction with thrombin. For the first time, using steered molecular dynamics (SMD) simulations, we have successfully simulated the unfolding process of native TBA G‐quadruplex. The unfolding pathway proposed is in agreement with previously reported experimental NMR data. Moreover, the critical intermediate structure in the unfolding pathway, predicted by the NMR results, was identified. The structural characteristics of several TBA oligonucleotides modified with locked nucleoside (LNA) or 2′‐O‐methyl‐nucleoside (MNA) at different positions and number were also investigated by CD spectroscopy. An oligonucleotide substituted with either LNA or MNA at position 2 folds into a native‐like G‐quadruplex, while doubly substituted derivatives of TBA where LNA or MNA is incorporated at positions 11 and 14 are no longer able to form a G‐quadruplex. Starting from the same initial intermediate structure, we successfully overcame sampling limitations, and simulated the large conformational variations in structures of native TBA and modified TBAs by classic MD. Analysis of the models showed that inversion of the glycosyl orientation at position 14 contributes significantly to the disruption of G‐quadruplex formation in both of the di‐substituted modified TBA systems. Our calculations provide a simple and reliable theoretical model that can be used to investigate and predict the effects of the modifications of an oligonucleotide on the resultant G‐quadruplex structure. In addition, the computational protocol described can also be applied for other G‐quadruplex systems.
trans,cis,cis‐Bis(benzoato)dichlorido(cyclohexane‐1R,2R‐diamine)platinum(IV): a Prodrug Candidate for the Treatment of Oxaliplatin‐Refractory Colorectal Cancer
Authors: Gandin Valentina , Marzano Cristina , Pelosi Giorgio , Ravera Mauro , Gabano Elisabetta , Osella Domenico 
Published: April 2014

AbstractThe gold standard for the treatment of metastatic colorectal cancer consists of combination chemotherapy. Over time, however, the development of chemoresistant tumor clones leads to relapse. It may be possible to overcome oxaliplatin chemoresistance in colorectal cancer cells by exploiting a complex obtained from the insertion of the cyclohexane‐1R,2R‐diamine carrier ligand (the same diamine present in oxaliplatin) into an octahedral PtIV scaffold with high lipophilicity conferred by two benzoate axial ligands. Herein we report the synthesis, characterization (including X‐ray structure), biological activity, and cellular accumulation of trans,cis,cis‐bis(benzoato)dichlorido(cyclohexane‐1R,2R‐diamine)platinum(IV) complex in a panel of several human cancer cell lines, including a colon carcinoma cell line resistant to oxaliplatin. The compound under investigation shows the best performance in terms of in vitro anti‐proliferative activity and ability to overcome chemoresistance, with respect to oxaliplatin and some other PtII reference complexes. This result is likely related to the high lipophilicity shown by the title compound that favors its cellular accumulation by passive diffusion.
Experiences building Globus Genomics: a next‐generation sequencing analysis service using Galaxy, Globus, and Amazon Web Services
Authors: Madduri Ravi K. , Sulakhe Dinanath , Lacinski Lukasz , Liu Bo , Rodriguez Alex , Chard Kyle , Dave Utpal J. , Foster Ian T. 
Published: April 2014

SUMMARYWe describe Globus Genomics, a system that we have developed for rapid analysis of large quantities of next‐generation sequencing genomic data. This system achieves a high degree of end‐to‐end automation that encompasses every stage of data analysis including initial data retrieval from remote sequencing centers or storage (via the Globus file transfer system); specification, configuration, and reuse of multistep processing pipelines (via the Galaxy workflow system); creation of custom Amazon Machine Images and on‐demand resource acquisition via a specialized elastic provisioner (on Amazon EC2); and efficient scheduling of these pipelines over many processors (via the HTCondor scheduler). The system allows biomedical researchers to perform rapid analysis of large next‐generation sequencing datasets in a fully automated manner, without software installation or a need for any local computing infrastructure. We report performance and cost results for some representative workloads. Copyright © 2014 John Wiley & Sons, Ltd.
Thermodynamics and 2H NMR Study on the Insertion of Small Quinones into a Discotic Nematic Lyotropic Liquid Crystal
Authors: Bahamonde‐Padilla Víctor Eduardo , López‐Cascales José Javier , Araya‐Maturana Ramiro , Martínez‐Cifuentes Maximiliano , Weiss López Boris Enrique 
Published: April 2014

AbstractA detailed description of the distribution, interaction, and dynamics of molecules with biological activity dissolved in a hydrophobic bilayer, a simple model of a biological membrane, provides valuable information for a better understanding of drug functioning, which can be very useful in drug design. Here we present an 2H NMR and molecular dynamics study on the insertion, distribution, interactions, and thermodynamics of two biologically active molecules, 9,10‐dihydroxy‐4,4‐dimethyl‐1,4,5,8‐tetrahydroanthracen‐1‐one (HQ), with anticancer activity, and 4,4‐dimethyl‐1,4,5,8,9,10‐hexahydroanthracen‐1,9,10‐trione (Q) a fungicide, dissolved in a nematic discotic lyotropic liquid crystal (ndllc) composed of sodium dodecylsulphate (SDS), decanol (DecOH) and Na2SO4 in water. 2H NMR quadrupole splittings (ΔνQ) and longitudinal relaxation times (T1) from HQ‐d6, Q‐d4, DecOH‐α‐d2, partially deuterated water, and SDS‐d25 were measured and several molecular dynamics trajectories were also calculated. In particular, ΔG, ΔH, and ΔS profiles for the process of both molecules crossing the bilayer were estimated. It was evidenced that the insertion of both molecules into the aggregate is a spontaneous process, and the molecules are mainly distributed in the internal side of the interface. Addition of HQ or Q decreased the mobility of all aggregate components, but this effect was more pronounced for HQ. The rotational correlation time of Q allowed an estimate of 5.3 cP for the microviscosity inside the ndllc aggregate, in the order of previously measured values in similar environments. Both guest molecules display similar free‐energy profiles for the process of crossing the bilayer, with a calculated barrier height of 25 and 36 kJ mol−1 for HQ and Q, respectively.
Effect of Nanoscale Confinement on Freezing of Modified Water at Room Temperature and Ambient Pressure
Authors: Deshmukh Sanket , Kamath Ganesh , Sankaranarayanan Subramanian K. R. S. 
Published: April 2014

AbstractUnderstanding the phase behavior of confined water is central to fields as diverse as heterogeneous catalysis, corrosion, nanofluidics, and to emerging energy technologies. Altering the state points (temperature, pressure, etc.) or introduction of a foreign surface can result in the phase transformation of water. At room temperature, ice nucleation is a very rare event and extremely high pressures in the GPa–TPa range are required to freeze water. Here, we perform computer experiments to artificially alter the balance between electrostatic and dispersion interactions between water molecules, and demonstrate nucleation and growth of ice at room temperature in a nanoconfined environment. Local perturbations in dispersive and electrostatic interactions near the surface are shown to provide the seed for nucleation (nucleation sites), which lead to room temperature liquid–solid phase transition of confined water. Crystallization of water occurs over several tens of nanometers and is shown to be independent of the nature of the substrate (hydrophilic oxide vs. hydrophobic graphene and crystalline oxide vs. amorphous diamond‐like carbon). Our results lead us to hypothesize that the freezing transition of confined water can be controlled by tuning the relative dispersive and electrostatic interaction.
Syntheses of Functionalized Allylamines via Lithiated Intermediates
Authors: Firdous Samia , Kazmaier Uli 
Published: April 2014

AbstractLithiated allylamines are easily available by tin–lithium exchange from stannylated allylamines and are suitable nucleophiles for a wide range of conversions. With aldehydes and ketones, aminomethylated allyl alcohols are formed, whereas the reaction with α‐brominated ketones gives rise to vinyl epoxides or aldehydes, depending on the reaction and workup conditions used.
Synthesis and Selected Reactivity Studies of a Dissymmetric (Phosphinoylmethylpyridine N‐Oxide) Methylamine Platform
Authors: Ouizem Sabrina , Pailloux Sylvie L. , Ray Alisha D. , Duesler Eileen N. , Dickie Diane A. , Paine Robert T. , Hay Benjamin P. 
Published: April 2014

AbstractEfficient syntheses for the precursor molecules, 2‐{6‐[((diphenylphosphoryl)methyl)pyridin‐2‐yl]methyl}isoindoline‐1,3‐dione (2), 2‐[(1,3‐dioxoisoindolin‐2‐yl)methyl]‐6‐[(diphenylphosphoryl)methyl]pyridine 1‐oxide (3), and their 6‐[bis(2‐(trifluoromethyl)phenyl)phosphoryl]methyl analogues are reported along with their transformations into the dissymmetric ligands, [(6‐(aminomethyl)pyridin‐2‐yl)methyl]diphenylphosphine oxide (4), 2‐(aminomethyl)‐6‐[(diphenylphosphoryl)methyl]pyridine 1‐oxide (5) and 2‐(aminomethyl)‐6‐{[bis(2‐(trifluoromethyl)phenyl)phosphoryl]methyl}pyridine 1‐oxide (5‐F). Selected reactivity of the aminomethyl substituent of 4 and 5, as well as complexation reactions of several of the compounds with lanthanide(III) ions are described. Molecular structures of three uniquely different complexes, {Pr{2‐[HC(O)N(H)CH2]‐6‐[Ph2P(O)CH2]C5H3NO}(NO3)3(MeOH)}2, {Eu{2‐[(Me2N)2CN(H+)CH2]‐6‐[Ph2P(O)CH2]C5H3N(H)+}(NO3)4(OMe)} and {Er{2‐[(C8H4O2)NCH2]‐6‐[Ph2P(O)CH2]C5H3N(O)}(NO3)3(MeOH)}·(CH3)2CO, have been determined by single‐crystal X‐ray diffraction methods. The observed and computationally modeled structures that employ bidentate and tridentate ligand/metal interactions are compared. These results suggest further ligand modifications that should provide improved solvent extraction reagents.
In Situ Evaluation of the Anticancer Antibody Rituximab‐dsDNA Interaction Using a DNA‐Electrochemical Biosensor
Authors: Santarino Inês B. , Oliveira Severino Carlos B. , Oliveira‐Brett Ana Maria 
Published: April 2014

AbstractA multilayer dsDNA‐electrochemical biosensor for the in situ electrochemical evaluation of anticancer antibody rituximab (RTX) interaction with double‐stranded DNA (dsDNA), with differential pulse voltammetry was used. The decrease of the dsDNA oxidation peaks with incubation time was observed and was confirmed that RTX binds causing dsDNA condensation, and no evidence for DNA base oxidative damage was detected electrochemically. Nondenaturing agarose gel‐electrophoresis of RTX‐dsDNA samples confirmed the occurrence of condensation in the dsDNA structure.
Ultrasensitive and Simple Method for Determination of N‐Acetyl‐L‐Cysteine in Drug Formulations Using a Diamond Sensor
Authors: Nantaphol Siriwan , Chailapakul Orawon , Siangproh Weena 
Published: April 2014

AbstractA boron‐doped diamond (BDD) electrode coupled to flow injection analysis (FIA) was firstly developed for determination of N‐acetyl‐L‐cysteine (NAC) in drug formulations. The effects of experimental parameters including pH, applied potential and scan rate on the response were investigated. FIA amperometry was applied as an automatic method for the quantitative detection of trace amounts of NAC. A wide linear range of 0.5–50 µmol/L and a low detection limit of 10 nmol/L were obtained. The results of amperometric determinations show a very good reproducibility, and the RSD for the measurement based on 10 measurements was <3.7 % and <4.1 % for intra‐ and inter‐day, respectively. The benefits of the proposed method are fast, simple, sensitive and no requirement of complicated operational steps.
Local acting Sticky‐trap inhibits vascular endothelial growth factor dependent pathological angiogenesis in the eye
Authors: Michael Iacovos P , Westenskow Peter D , Hacibekiroglu Sabiha , Greenwald Alissa Cohen , Ballios Brian G , Kurihara Toshihide , Li Zhijie , Warren Carmen M , Zhang Puzheng , Aguilar Edith , Donaldson Laura , Marchetti Valentina , Baba Takeshi , Hussein Samer M , Sung Hoon‐Ki , Iruela‐Arispe M Luisa , Rini James M , van der Kooy Derek , Friedlander Martin , Nagy Andras 
Published: April 2014

AbstractCurrent therapeutic antiangiogenic biologics used for the treatment of pathological ocular angiogenesis could have serious side effects due to their interference with normal blood vessel physiology. Here, we report the generation of novel antivascular endothelial growth factor‐A (VEGF) biologics, termed VEGF “Sticky‐traps,” with unique properties that allow for local inhibition of angiogenesis without detectable systemic side effects. Using genetic and pharmacological approaches, we demonstrated that Sticky‐traps could locally inhibit angiogenesis to at least the same extent as the original VEGF‐trap that also gains whole‐body access. Sticky‐traps did not cause systemic effects, as shown by uncompromised wound healing and normal tracheal vessel density. Moreover, if injected intravitreally, recombinant Sticky‐trap remained localized to various regions of the eye, such as the inner‐limiting membrane and ciliary body, for prolonged time periods, without gaining access either to the photoreceptors/choriocapillaris area or the circulation. These unique pharmacological characteristics of Sticky‐trap could allow for safe treatment of pathological angiogenesis in patients with diabetic retinopathy and retinopathy of pre‐maturity.
Effective treatment of mitochondrial myopathy by nicotinamide riboside, a vitamin B3
Authors: Khan Nahid A , Auranen Mari , Paetau Ilse , Pirinen Eija , Euro Liliya , Forsström Saara , Pasila Lotta , Velagapudi Vidya , Carroll Christopher J , Auwerx Johan , Suomalainen Anu 
Published: April 2014

AbstractNutrient availability is the major regulator of life and reproduction, and a complex cellular signaling network has evolved to adapt organisms to fasting. These sensor pathways monitor cellular energy metabolism, especially mitochondrial ATP production and NAD+/NADH ratio, as major signals for nutritional state. We hypothesized that these signals would be modified by mitochondrial respiratory chain disease, because of inefficient NADH utilization and ATP production. Oral administration of nicotinamide riboside (NR), a vitamin B3 and NAD+ precursor, was previously shown to boost NAD+ levels in mice and to induce mitochondrial biogenesis. Here, we treated mitochondrial myopathy mice with NR. This vitamin effectively delayed early‐ and late‐stage disease progression, by robustly inducing mitochondrial biogenesis in skeletal muscle and brown adipose tissue, preventing mitochondrial ultrastructure abnormalities and mtDNA deletion formation. NR further stimulated mitochondrial unfolded protein response, suggesting its protective role in mitochondrial disease. These results indicate that NR and strategies boosting NAD+ levels are a promising treatment strategy for mitochondrial myopathy.