NMR and EPR

Molecular systems important to biology, environmental remediation and sustainability are studied using a suite of nuclear magnetic resonance (NMR) spectrometers with frequencies ranging from 300 to 850 MHz. A pair of electron paramagnetic resonance (EPR) spectrometers complement the capability. See a complete list of NMR and EPR instruments.

Description

Interfacial and in situ biology—Innovative NMR instrumentation and techniques for probing properties of macromolecular cellular assemblies and in situ and ex situ metabolic processes, as well as for exploring biological membrane proteins in the solid state. Unique EPR and variable-temperature NMR approaches to explore structure and properties of redox metal centers critical catalysis, environmental chemistry and cell biology.

Environmental chemistry— EMSL offers a unique NMR system for radiological studies. Users can perform magic angle spinning of highly radioactive samples with a novel hermetically sealed 3.2mm NMR probe. These tools allow users to apply NMR techniques to critical areas of radiological research, including the study of radioactive waste processing and storage.

Interfacial and in situ chemistry—Leading-edge solid-state NMR probe technology to analyze and quantify properties of advanced energy materials, fuel cells and real-time catalytic processes. High power pulsed field gradient diffusion capabilities for liquid and solid samples.

EMSL offers unique and custom NMR and EPR tools, including probes for specialized studies.

  • NMR spectrometers, ranging from 300 MHz to 850 MHz for high-field liquid-state, solid-state and micro-imaging techniques
  • W- and X-band pulsed EPR spectremeter for probing metal centers in biological and materials systems
  • NMR metabolomics capabilities
  • Extreme-temperature probes, both high and low temperatures
  • Virtual NMR tools for remote access to spectrometer systems.

Instruments

Highlighted Research Applications Characterization of natural and soil organic matter (NOM and SOM) CO2 sequestration investigations via high-...
Custodian(s): Sarah D Burton, David Hoyt
Research Applications Characterization of quadrupolar nuclei for inorganic and biological materials and natural sediments Cryogenic NMR capabilities...
Highlighted Research Applications EMSL's Bruker 500-MHz WB spectrometer is uniquely tailored for in vivo studies: Microbial biofilms relevant to...
Custodian(s):
Type of Instrument:
Nuclear Magnetic Resonance Spectrometer (NMR)
Research Applications Dynamics studies via 2H NMR Characterization of quadrupolar nuclei for materials and biological samples Characterization of...
Highlighted Research Applications Structural biology Protein structure and dynamics Nuclei acid structure and dynamics. Metabolomics Eukaryotic and...
Custodian(s): Nancy Isern, David Hoyt

Publications

Nickel complexes were prepared with diphosphine ligands that contain pendant amines, and these complexes catalytically oxidize primary and secondary...
Nitrogen-doped porous carbon (NPC) and multi-wall carbon nanotube (MWCNT) have been frequently studied to immobilize sulfur in lithium-sulfur (Li-S)...
The surface chemistry of metal oxide particles is governed by the charge that develops at the interface with aqueous solution. Mineral transformation...
Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on...
Thermophilic proteins have found extensive use in research and industrial applications due to their high stability and functionality at elevated...

Science Highlights

Posted: November 20, 2015
The Science Phototrophic microbial mats are among the most diverse ecosystems in nature. These self-sustaining natural ecosystems are composed of...
Posted: October 20, 2015
The Science Permafrost soils near the North Pole contain roughly twice the amount of carbon stored in the atmosphere today; but for now, most of...
Posted: September 23, 2015
The Science Natural organic matter (NOM) is a mixture of organic molecules derived primarily from the natural decay of plant matter. Understanding...
Posted: August 14, 2015
Active sites are where catalytic reactions occur; however, slow or failed sties result in higher costs and lower production rates.  To improve...
Posted: March 27, 2015
Zeolites are widely used in industry as catalysts, but many of the characteristics of these materials are challenging to understand and predict. Led...

Instruments

This is a proposal to use advanced solid-state NMR methods to elucidate the architecture and arrangement of cell walls of plants, grass species in...
This proposal aims to provide molecular insight into elementary reaction steps and their kinetics in condensed phases at an atomic and molecular...
A critical step in the lignocellulosic biofuels pipeline is the extraction of fermentable sugars from plant biomass. Extracellular fungal enzymes are...
The Joint Center for Energy Storage Research (JCESR) is performing transformational research to overcome critical scientific and technical barriers...
Our research program strives to provide new insight into the fundamental molecular-scale dynamics, energetics, and reactivity of geochemically...

Molecular systems important to biology, environmental remediation and sustainability are studied using a suite of nuclear magnetic resonance (NMR) spectrometers with frequencies ranging from 300 to 850 MHz. A pair of electron paramagnetic resonance (EPR) spectrometers complement the capability. See a complete list of NMR and EPR instruments.

Effect of Graphene with Nanopores on Metal Clusters.

Abstract: 

Porous graphene, which is a novel type of defective graphene, shows excellent potential as a support material for metal clusters. In this work, the stability and electronic structures of metal clusters (Pd, Ir, Rh) supported on pristine graphene and graphene with different sizes of nanopore were investigated by first-principle density functional theory (DFT) calculations. Thereafter, CO adsorption and oxidation reaction on the Pd-graphene system were chosen to evaluate its catalytic performance. Graphene with nanopore can strongly stabilize the metal clusters and cause a substantial downshift of the d-band center of the metal clusters, thus decreasing CO adsorption. All binding energies, d-band centers, and adsorption energies show a linear change with the size of the nanopore: a bigger size of nanopore corresponds to a stronger metal clusters bond to the graphene, lower downshift of the d-band center, and weaker CO adsorption. By using a suitable size nanopore, supported Pd clusters on the graphene will have similar CO and O2 adsorption ability, thus leading to superior CO tolerance. The DFT calculated reaction energy barriers show that graphene with nanopore is a superior catalyst for CO oxidation reaction. These properties can play an important role in instructing graphene-supported metal catalyst preparation to prevent the diffusion or agglomeration of metal clusters and enhance catalytic performance. This work was supported by National Basic Research Program of China (973Program) (2013CB733501), the National Natural Science Foundation of China (NSFC-21176221, 21136001, 21101137, 21306169, and 91334013). D. Mei acknowledges the support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) and by the National Energy Research Scientific Computing Center (NERSC).

Citation: 
Zhou H, X Chen, L Wang, X Zhong, G Zhuang, X Li, D Mei, and J Wang.2015."Effect of Graphene with Nanopores on Metal Clusters."Physical Chemistry Chemical Physics. PCCP 17(37):24420-24426. doi:10.1039/c5cp04368a
Authors: 
H Zhou
X Chen
L Wang
X Zhong
G Zhuang
X Li
D Mei
J Wang
Capabilities: 
Volume: 
17
Issue: 
37
Pages: 
24420-24426
Publication year: 
2015

Dynamic Structural Changes of SiO2 Supported Pt−Ni Bimetallic Catalysts over Redox Treatments Revealed by NMR and EPR.

Abstract: 

SiO2 supported Pt−Ni bimetallic catalysts with different nickel loadings were prepared and their structural changes after redox treatments were studied by XRD, NMR, and EPR. It is found that the paramagnetic Ni species are mainly located on the surface of silica lattice. The relaxation of detected 29Si nuclei in our samples is mainly governed by a spin-diffusion mechanism. The paramagnetic effects are reflected in the spin−lattice relaxation of Q4 species, with the oxidized samples presenting faster relaxation rates than the corresponding reduced ones. Meanwhile the Q3 species, which are in close contact with the paramagnetic nickel ions, are “spectrally invisible”. In reducing atmosphere Ni gradually diffuses into Pt NPs to form PtNi alloys. While under oxidization treatment, the alloyed Ni atoms migrate outward from the core of Pt NPs and are oxidized. The main EPR spectrum results from reduced nickel species, and the reduced samples show stronger EPR signal than the corresponding oxidized ones. However, in the reduced samples, the superparamagnetic or ferromagnetic metallic Ni particles were inside the PtNi NPs, making their influence on the 29Si relaxation in the SiO2 support weaker than the oxidized samples.

Citation: 
Xu S, ED Walter, Z Zhao, MY Hu, X Han, JZ Hu, and X Bao.2015."Dynamic Structural Changes of SiO2 Supported Pt?Ni Bimetallic Catalysts over Redox Treatments Revealed by NMR and EPR."Journal of Physical Chemistry C 119(36):21219-21226. doi:10.1021/acs.jpcc.5b06344
Authors: 
Xu S
ED Walter
Z Zhao
MY Hu
X Han
JZ Hu
X Bao
Capabilities: 
Volume: 
119
Issue: 
36
Pages: 
21219-21226
Publication year: 
2015

Regulation of electron transfer processes affects phototrophic mat structure and activity.

Abstract: 

Phototrophic microbial mats are among the most diverse ecosystems in nature. These systems undergo daily cycles in redox potential caused by variations in light energy input and metabolic interactions among the microbial species. In this work, solid electrodes with controlled potentials were placed under mats to study the electron transfer processes between the electrode and the microbial mat. The phototrophic microbial mat was harvested from Hot Lake, a hypersaline, epsomitic lake located near Oroville (Washington, USA). We operated two reactors: graphite electrodes were polarized at potentials of -700 mVAg/AgCl (cathodic mat system) and +300 mVAg/AgCl (anodic mat system) and the electron transfer rates between the electrode and mat were monitored. We observed a diel cycle of electron transfer rates for both anodic and cathodic mat systems. Interestingly, the cathodic mats generated the highest reducing current at the same time points that the anodic mats showed the highest oxidizing current. To characterize the physicochemical factors influencing electron transfer processes, we measured depth profiles of dissolved oxygen and sulfide in the mats using microelectrodes. We further demonstrated that the mat-to-electrode and electrode-to-mat electron transfer rates were light- and temperature-dependent. Using nuclear magnetic resonance (NMR) imaging, we determined that the electrode potential regulated the diffusivity and porosity of the microbial mats. Both porosity and diffusivity were higher in the cathodic mats than in the anodic mats. We also used NMR spectroscopy for high-resolution quantitative metabolite analysis and found that the cathodic mats had significantly higher concentrations of osmoprotectants such as betaine and trehalose. Subsequently, we performed amplicon sequencing across the V4 region of the 16S rRNA gene of incubated mats to understand the impact of electrode potential on microbial community structure. Our results suggest that it is possible to electrochemically regulate the structure, community composition, and function of microbial mats.

Citation: 
Ha PT, RS Renslow, E Atci, PN Reardon, SR Lindemann, JK Fredrickson, DR Call, and H Beyenal.2015."Regulation of electron transfer processes affects phototrophic mat structure and activity."Frontiers in Microbiology 6:Article No. 909. doi:10.3389/fmicb.2015.00909
Authors: 
Ha PT
RS Renslow
E Atci
PN Reardon
SR Lindemann
JK Fredrickson
DR Call
H Beyenal
Facility: 
Volume: 
Issue: 
Pages: 
Publication year: 
2015

Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide.

Abstract: 

Continental flood basalts are attractive formations for geologic sequestration of carbon dioxide because of their reactive divalent-cation containing silicates, such as forsterite (Mg2SiO4), suitable for long-term trapping of CO2 mineralized as metal carbonates. The goal of this study was to investigate at a molecular level the carbonation products formed during the reaction of forsterite with supercritical CO2 (scCO2) as a function of the concentration of H2O adsorbed to the forsterite surface. Experiments were performed at 50 °C and 90 bar using an in situ IR titration capability, and post-reaction samples were examined by ex situ techniques, including SEM, XPS, FIB-TEM, TGA-MS, and MAS-NMR. Carbonation products and reaction extents varied greatly with adsorbed H2O. We show for the first time evidence of Mg-carbonate surface complexation under wet scCO2 conditions. Carbonate is found to be coordinated to Mg at the forsterite surface in a predominately bidentate fashion at adsorbed H2O concentrations below 27 µmol/m2. Above this concentration and up to 76 µmol/m2, monodentate coordinated complexes become dominant. Beyond a threshold adsorbed H2O concentration of 76 µmol/m2, crystalline carbonates continuously precipitate as magnesite, and the particles that form are hundreds of times larger than the estimated thicknesses of the adsorbed water films of about 7 to 15 Å. At an applied level, these results suggest that mineral carbonation in scCO2 dominated fluids near the wellbore and adjacent to caprocks will be insignificant and limited to surface complexation, unless adsorbed H2O concentrations are high enough to promote crystalline carbonate formation. At a fundamental level, the surface complexes and their dependence on adsorbed H2O concentration give insights regarding forsterite dissolution processes and magnesite nucleation and growth.

Citation: 
Loring JS, J Chen, P Benezeth Ep Gisquet, O Qafoku, ES Ilton, NM Washton, CJ Thompson, PF Martin, BP McGrail, KM Rosso, AR Felmy, and HT Schaef.2015."Evidence for Carbonate Surface Complexation during Forsterite Carbonation in Wet Supercritical Carbon Dioxide."Langmuir 31(27):7533-7543. doi:10.1021/acs.langmuir.5b01052
Authors: 
Qafoku Odeta
Nancy M Washton
Kevin M Rosso
Loring JS
J Chen
P Benezeth Ep Gisquet
O Qafoku
ES Ilton
NM Washton
CJ Thompson
PF Martin
BP McGrail
KM Rosso
AR Felmy
HT Schaef
Capabilities: 
Volume: 
31
Issue: 
27
Pages: 
7533-7543
Publication year: 
2015

The mechanism of neutral red-mediated microbial electrosynthesis in Escherichia coli: menaquinone reduction.

Abstract: 

The aim of this work was to elucidate the mechanism of mediated microbial electrosynthesis via neutral red from an electrode to fermenting Escherichia coli cultures in a bioelectrochemical system. Chemical reduction of NAD+ by reduced neutral red did not occur as predicted. Instead, neutral red was shown to reduce the menaquinone pool in the inner bacterial membrane. The reduced menaquinone pool altered fermentative metabolite production via the arcB redox-sensing cascade in the absence of terminal electron acceptors. When the acceptors DMSO, fumarate, or nitrate were provided, as many as 19% of the electrons trapped in the reduced acceptors were derived from the electrode. These results demonstrate the mechanism of neutral red-mediated microbial electrosynthesis during fermentation as well as how neutral red enables microbial electrosynthesis of reduced terminal electron acceptors.

Citation: 
Harrington TD, VN Tran, A Mohamed, RS Renslow, S Biria, L Orfe, DR Call, and H Beyenal.2015."The mechanism of neutral red-mediated microbial electrosynthesis in Escherichia coli: menaquinone reduction."Bioresource Technology 192:689-695. doi:10.1016/j.biortech.2015.06.037
Authors: 
S Ryan
Harrington TD
VN Tran
A Mohamed
RS Renslow
S Biria
L Orfe
DR Call
H Beyenal
Facility: 
Volume: 
Issue: 
Pages: 
Publication year: 
2015

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Dr. Washton is a key player in coupling solid-state NMR  (ssNMR) with computational chemistry for predictions of reaction site structure and kinetics, and to provide users with an integrated system for making predictions of NMR parameters based...