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Molecular adsorbant

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https://www.readbyqxmd.com/read/29155903/a-surprising-substituent-effect-in-corroles-on-the-electrochemical-activation-of-oxygen-reduction
#1
Naomi Levy, Jennifer S Shpilman, Hilah C Honig, Dan T Major, Lior Elbaz
Four β-pyrrole-substituted cobalt(iii) corroles were studied as electrocatalysts for the oxygen reduction reaction. The results disclose high dependence of the corrole's performance on its substituents, but once adsorbed on a high surface area carbon, this effect vanishes, resulting in a better catalytic performance than most well-defined molecular electrocatalysts for this reaction.
November 20, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29153876/real-time-evaluation-of-natural-organic-matter-deposition-processes-onto-model-environmental-surfaces
#2
Wenlu Li, Peng Liao, Trey Oldham, Yi Jiang, Chao Pan, Songhu Yuan, John D Fortner
Natural organic matter (NOM) is ubiquitous in aqueous systems and dynamically partitions onto/from environmental surfaces. However, such interfacial processes have not been uniformly quantified in situ and in real time. In this work, adsorption and deposition processes of Suwannee River humic acid (SRHA) and Suwannee River fulvic acid (SRFA), as model NOM, were evaluated for a series of environmentally relevant interfaces. Real-time, interfacial phenomenon, including deposition, release, and adlayer viscoelastic properties, were quantified over a variety of water chemistries via quartz crystal microbalance with dissipation monitoring (QCM-D)...
November 9, 2017: Water Research
https://www.readbyqxmd.com/read/29152034/orientation-dependent-work-function-modification-using-substituted-pyrene-based-acceptors
#3
O T Hofmann, H Glowatzki, C Bürker, G M Rangger, B Bröker, J Niederhausen, T Hosokai, I Salzmann, R-P Blum, R Rieger, A Vollmer, P Rajput, A Gerlach, K Müllen, F Schreiber, E Zojer, N Koch, S Duhm
The adsorption of molecular acceptors is a viable method for tuning the work function of metal electrodes. This, in turn, enables adjusting charge injection barriers between the electrode and organic semiconductors. Here, we demonstrate the potential of pyrene-tetraone (PyT) and its derivatives dibromopyrene-tetraone (Br-PyT) and dinitropyrene-tetraone (NO2-PyT) for modifying the electronic properties of Au(111) and Ag(111) surfaces. The systems are investigated by complementary theoretical and experimental approaches, including photoelectron spectroscopy, the X-ray standing wave technique, and density functional theory simulations...
November 9, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
https://www.readbyqxmd.com/read/29149812/architectures-and-mechanical-properties-of-drugs-and-complexes-of-surface-active-compounds-at-air-water-and-oil-water-interfaces
#4
Dipak K Sarker
BACKGROUND: Drugs can represents a multitude of compounds from proteins and peptides, such as growth hormones and insulin and on to simple organic molecules such as flurbiprofen, ibuprofen and lidocaine. Given the chemical nature of these compounds two features are always present. A portion or portions of the molecule that has little affinity for apolar surfaces and media and the opposite a series of part or one large part that has considerable affinity for hydrophilic, polar or charged media and surfaces...
November 17, 2017: Current Drug Discovery Technologies
https://www.readbyqxmd.com/read/29148556/co2-adsorption-on-anatase-tio2-101-surfaces-a-combination-of-uhv-ftirs-and-first-principles-studies
#5
Yunjun Cao, Min Yu, Shandong Qi, Tingting Wang, Shiming Huang, Zhengfeng Ren, Shishen Yan, Shujun Hu, Mingchun Xu
The CO2 adsorption and dynamic behaviors on single crystal anatase TiO2(101) surfaces were investigated by UHV-FTIRS and first-principles calculations. The IRRAS results at 90 K show that the ν3(OCO) asymmetric stretching vibration of adsorbed CO2 exhibits band splitting at rather low CO2 coverage in p-polarized IR spectra for the IR beam incident along the [101[combining macron]] direction. Co-adsorbed CO can prevent such band splitting. Ab initio molecular dynamics (AIMD) simulations revealed that the adsorbed CO2 at finite temperature does not keep a stationary adsorption state but keeps a certain swing motion: one end of the linear CO2 molecule binds to surface Ti5c sites and the other end swings within the (010) plane with a tilted angle distribution ranging from 10° to 60° relative to the [101[combining macron]] direction...
November 17, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29144735/removal-of-pb-ii-ion-using-pamam-dendrimer-grafted-graphene-and-graphene-oxide-surfaces-a-molecular-dynamics-study
#6
Anitha Kommu, Vasumathi Velachi, M Natalia Dias Soeiro Cordeiro, Jayant Kumar Singh
The dendrimer polyamidoamine (PAMAM) has been widely applied in environmental applications as adsorbents for wastewater treatment. In this work, molecular dynamics simulations are conducted to understand the effect of dendrimer grafted graphene and graphene oxide on the structural and dynamical properties of Pb2+ ion. The adsorption capacity of the metal ion is improved significantly, over 60%, using carboxyl terminal groups of dendrimer molecule grafted on graphene oxide surface. We examine the self-diffusion coefficient and residence time of Pb2+ ion near graphene and graphene oxide surfaces grafted with PAMAM dendrimers using terminal groups, -COO- and -OH...
November 16, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/29143004/adsorption-parameters-and-phase-behaviour-of-non-ionic-surfactants-at-liquid-interfaces
#7
Radomir Iliev Slavchov, Ivan Boyanov Ivanov
A reasonable adsorption model is one that allows all adsorption parameters (adsorption constant, hard-disc area α, attraction parameter β) of a surfactant at a liquid interface to be predicted accurately as a function of the molecular structure and medium conditions. However, the established adsorption models of van der Waals and Frumkin lead to inconsistencies, such as negative β at water|oil, α significantly larger than the crystallographic area of the molecule, and phase behaviour that contradicts the experimental observations...
November 16, 2017: Soft Matter
https://www.readbyqxmd.com/read/29142616/scaling-relations-for-acidity-and-reactivity-of-zeolites
#8
Chong Liu, Ionut Tranca, Rutger A van Santen, Emiel J M Hensen, Evgeny A Pidko
Zeolites are widely applied as solid acid catalysts in various technological processes. In this work we have computationally investigated how catalytic reactivity scales with acidity for a range of zeolites with different topologies and chemical compositions. We found that straightforward correlations are limited to zeolites with the same topology. The adsorption energies of bases such as carbon monoxide (CO), acetonitrile (CH3CN), ammonia (NH3), trimethylamine (N(CH3)3), and pyridine (C5H5N) give the same trend of acid strength for FAU zeolites with varying composition...
October 26, 2017: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
https://www.readbyqxmd.com/read/29136893/study-on-molecularly-imprinted-nanoparticle-modified-microplates-for-pseudo-elisa-assays
#9
Lucia Cenci, Chiara Piotto, Paolo Bettotti, Alessandra Maria Bossi
Nanosized Molecularly Imprinted Polymers (nanoMIPs) are designed artificial nanoreceptors with a predetermined selectivity and specificity for a given analyte, lately proposed as a replacement to antibodies in immunoassays. The nanoMIP-plate preparation based on nanoparticle adsorption was studied with the aim to rationally identify and discuss the critical points in the nanoMIP-assay development, in an example based on the iron homeostasis biomarker hepcidin and hepcidin-specific nanoMIPs (Kd = 9nM). Plates were prepared by deposition and drying of nanoMIP (0...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136855/molecularly-imprinted-polymer-mip-membrane-assisted-direct-spray-ionization-mass-spectrometry-for-agrochemicals-screening-in-foodstuffs
#10
Igor Pereira, Marcella Ferreira Rodrigues, Andréa Rodrigues Chaves, Boniek Gontijo Vaz
Paper spray ionization (PSI) has some limitations such as low sensitivity and ionization suppression when complex samples are analyzed. The use of sample preparation devices directly coupled to MS can avoid these restrictions. Molecularly imprinted polymers (MIPs) are materials widely used as adsorbent in sample preparation methods such as solid-phase extraction and solid-phase microextraction, and they can provide specifics cavities with affinity to a target molecule. Here, we introduce a new MIP membrane spray ionization method combining MIP and PSI...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136826/preparation-and-evaluation-of-magnetic-molecularly-imprinted-polymers-for-the-specific-enrichment-of-phloridzin
#11
Die Gao, Dan-Dan Wang, Qi-Feng Fu, Lu-Jun Wang, Kai-Lian Zhang, Feng-Qing Yang, Zhi-Ning Xia
In present study, magnetic molecularly imprinted polymers (MMIPs) were successfully prepared for specific recognition and selective enrichment of phloridzin from the leaves of Malus doumeri (Bois) A. Chev and rats' plasma. The magnetic Fe3O4 were prepared by the solvothermal reaction method and followed by the modification of TEOS and functionalization with APTES. Using functionalized Fe3O4 particles as the magnetic cores, phloridzin as template, ethylene glycol dimethacrylate (EGDMA) as cross-linker and 2,2-azobisisobutyonnitrile (AIBN) as initiator, the MMIPs were prepared through APTES to associate the template on the surface of the magnetic substrate...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136197/mapping-vis-terahertz-%C3%A2-17-thz-surface-plasmons-sustained-on-native-and-chemically-functionalized-percolated-gold-thin-films-using-eels
#12
Patricia Abellan, Patrick Z El-Khoury, Quentin M Ramasse
Heterogeneous assemblies of molecules (Rhodamine B) adsorbed onto a nano-corrugated metallic surface (a percolated Au network) are investigated using electron energy loss spectroscopy in the scanning transmission electron microscope (STEM-EELS). Our first measurements target the native metallic substrate, which consists of a commercial Au thin film atop an ultrathin carbon membrane. The Au film displays a percolated morphology with nanostructures of estimated thickness ≤10 nm approximately. We observe a rich plasmonic response from the metallic substrate; one which varies nanometrically and spans the VIS-terahertz region...
November 9, 2017: Microscopy
https://www.readbyqxmd.com/read/29135011/hierarchical-self-assembly-of-enantiopure-and-racemic-helicenes-at-the-liquid-solid-interface-from-2d-to-3d
#13
Hai Cao, Andrea Minoia, Inge De Cat, Johannes Seibel, Deepali Waghray, Zhi Li, David Cornil, Kunal S Mali, Roberto Lazzaroni, Wim Dehaen, Steven De Feyter
The performance of organic nanostructures is closely related to the organization of the functional molecules. Frequently, molecular chirality plays a central role in the way molecules assemble at the supramolecular level. Herein we report the hierarchical self-assembly of benzo-fused tetrathia[7]helicenes on solid surfaces, from a single surface-bound molecule to well-defined microstructures, using a combination of various characterization techniques assisted by molecular modeling simulations. Similarities as well as discrepancies are revealed between homochiral and heterochiral aggregations by monitoring the hierarchical nucleation of helicenes on surfaces, where the impact of enantiopurity, concentration and adsorbate-substrate interaction on molecular organization are disclosed...
November 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/29134801/adsorbed-polyzwitterion-copolymer-layers-designed-for-protein-repellency-and-interfacial-retention
#14
S Kalasin, R A Letteri, T Emrick, M M Santore
Poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC), when end-tethered to surfaces by the adsorption of copolymeric cationic segments, forms adsorbed layers that substantially reduce protein adsorption. This study examined variations in the molecular architecture of copolymers containing cationic poly(trimethylammonium ethyl methacrylate (pTMAEMA) anchor blocks that adsorbed strongly to negative surfaces. With appropriate copolymer design, the pTMAEMA blocks were shielded, by pMPC tethers, from solution-phase proteins...
November 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29128721/preparation-of-mgal-edta-ldh-based-electrospun-nanofiber-membrane-and-its-adsorption-properties-of-copper-ii-from-wastewater
#15
Hong Chen, Jianhui Lin, Ning Zhang, Liangzhe Chen, Shuiping Zhong, Yao Wang, Wengong Zhang, Qidan Ling
Adsorption is recognized as one of the most promising technologies applied to remove heavy metals from contaminated water. However, the adsorption efficiency often decreases because of the aggregation and loss of adsorbents. Herein, a novel adsorbent was synthesized by intercalation ethylenediaminetetraacetic acid (EDTA) into layered double hydroxides (LDH) and subsequent encapsulated into PAN polymer matrix using electrospinning. The synthesized electrospun nanofiber membrane (MgAl-EDTA-LDH@PAN) was found to combine the advantages of LDH@PAN nanofiber membrane (high surface area, easy to separate, free from aggregation and loss) and EDTA (powerful chelating agent)...
November 8, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/29127855/dispersion-corrected-density-functional-study-of-co-oxidation-on-pristine-functionalized-doped-graphene-surfaces-in-aqueous-phase
#16
Mohd Riyaz, Sarita Yadav, Neetu Goel
The catalytic oxidation of CO by molecular oxygen (O2) over graphene, epoxy functionalized graphene and sulphur doped graphene surface is investigated theoretically by employing dispersion corrected Density Functional Theory. The adsorption of O2 and CO molecules over the pristine, functionalized and doped graphene surface has been compared. The channel for oxidation of CO to CO2 is elucidated in detail in the presence of aqueous solvent. Computations suggest that catalytic cycle of CO oxidation is initiated through the ER-mechanism, with the formation of a carbonate intermediate, the second pre-adsorbed CO reacts with the carbonate intermediate through LH-mechanism whereby, two CO2 molecules are released and adsorption surface becomes available for the subsequent reaction...
November 7, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/29127637/insights-into-doxycycline-adsorption-onto-graphene-nanosheet-a-combined-quantum-mechanics-thermodynamics-and-kinetic-study
#17
Rahele Rostamian, Hassan Behnejad
Recently, pharmaceutically active compounds including antibiotics have been detected in drinking water at very low levels, mostly nanogram/liter concentrations, proposing that these materials were unaffected by water treatment processes. Adsorption processes were suggested to play a significant role in the removal of antibiotics. In this study, the adsorption behavior of doxycycline (DC) in aqueous solution was evaluated. The four factors influencing the adsorption of DC onto graphene nanosheet (GNS) were studied...
November 10, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29126470/controlling-the-orientation-of-probe-molecules-on-surface-enhanced-raman-scattering-substrates-a-novel-strategy-to-improve-sensitivity
#18
Chengbin Sun, Tingkun Chen, Weidong Ruan, Bing Zhao, Qian Cong
Typically, the surface-enhanced Raman scattering (SERS) technique is employed in precious metallic substrates with spontaneously adsorbed probing molecules to acquire signals. Preferred chemical conditions including aggregate status, hydrophilic/hydrophobic surroundings, and smart linkers were created to enable the detection of targets in very low concentrations (lower than 1.0 × 10(-7) M). Although the sensitivity of SERS is applicable to certain areas, it is not satisfied in several cases that require obtaining good resolved signals involving extremely few surface molecules...
November 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29125651/an-ideal-molecular-sieve-for-acetylene-removal-from-ethylene-with-record-selectivity-and-productivity
#19
Bin Li, Xili Cui, Daniel O'Nolan, Hui-Min Wen, Mengdie Jiang, Rajamani Krishna, Hui Wu, Rui-Biao Lin, Yu-Sheng Chen, Daqiang Yuan, Huabin Xing, Wei Zhou, Qilong Ren, Guodong Qian, Michael J Zaworotko, Banglin Chen
Realization of ideal molecular sieves, in which the larger gas molecules are completely blocked without sacrificing high adsorption capacities of the preferred smaller gas molecules, can significantly reduce energy costs for gas separation and purification and thus facilitate a possible technological transformation from the traditional energy-intensive cryogenic distillation to the energy-efficient, adsorbent-based separation and purification in the future. Although extensive research endeavors are pursued to target ideal molecular sieves among diverse porous materials, over the past several decades, ideal molecular sieves for the separation and purification of light hydrocarbons are rarely realized...
November 10, 2017: Advanced Materials
https://www.readbyqxmd.com/read/29125303/position-dependent-dynamics-explain-pore-averaged-diffusion-in-strongly-attractive-adsorptive-systems
#20
William P Krekelberg, Daniel William Siderius, Vincent K Shen, Thomas M Truskett, Jeffrey R Errington
Using molecular simulations, we investigate the relationship between pore-averaged and position-dependent self-diffusivity of a fluid adsorbed in a strongly attractive pore as a function of loading. Previous work [Krekelberg et al., Langmuir 2013, 29, 14527] established that pore averaged self-diffusivity in the multilayer adsorption regime, where the fluid exhibits a dense "film" at the pore surface and a lower density "interior pore" region, is nearly constant as a function of loading. Here we show that this puzzling behavior can be understood in terms of how loading affects the fraction of particles that reside in the film and interior pore regions as well as their distinct dynamics...
November 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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