Vibrational Spectroscopy

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Hongxin Wang - One of the best experts on this subject based on the ideXlab platform.

  • hydride bridge in nife hydrogenase observed by nuclear resonance Vibrational Spectroscopy
    Nature Communications, 2015
    Co-Authors: Hideaki Ogata, Frank Neese, Hongxin Wang, Tobias Kramer, David Schilter, Vladimir Pelmenschikov, Maurice Van Gastel, Thomas B Rauchfuss
    Abstract:

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the (57)Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique 'wagging' mode involving H(-) motion perpendicular to the Ni(μ-H)(57)Fe plane was studied using (57)Fe-specific nuclear resonance Vibrational Spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)(57)Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe-CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)(57)Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)(57)Fe(CO)3](+) and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H(-) binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe-H moieties in other important natural and synthetic catalysts.

  • Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance Vibrational Spectroscopy
    Nature Communications, 2015
    Co-Authors: Hideaki Ogata, Frank Neese, Hongxin Wang, Thomas B Rauchfuss, Tobias Kramer, David Schilter, Vladimir Pelmenschikov, Maurice Van Gastel, Leland B Gee, Aubrey D. Scott
    Abstract:

    Understanding the catalytic mechanism of redox-active hydrogenases is a key to efficient hydrogen production and consumption. Here, the authors use nuclear resonance Vibrational Spectroscopy to study [NiFe]-hydrogenase, and observe a bridging hydride structure in an EPR silent intermediate. The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the ^57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H^− motion perpendicular to the Ni( μ -H)^57Fe plane was studied using ^57Fe-specific nuclear resonance Vibrational Spectroscopy and density functional theory (DFT) calculations. On Ni( μ -D)^57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe–CO/CN bands. Spectra have been interpreted by comparison with Ni( μ -H/D)^57Fe enzyme mimics [(dppe)Ni( μ -pdt)( μ -H/D)^57Fe(CO)_3]^+ and DFT calculations, which collectively indicate a low-spin Ni( II )( μ -H)Fe( II ) core for Ni-R, with H^− binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe–H moieties in other important natural and synthetic catalysts.

  • synthesis and Vibrational Spectroscopy of 57fe labeled models of nife hydrogenase first direct observation of a nickel iron interaction
    Chemical Communications, 2014
    Co-Authors: David Schilter, Hongxin Wang, Thomas B Rauchfuss, Vladimir Pelmenschikov, Yoshitaka Yoda, Leland B Gee, Florian Meier, Martin Kaupp, Stephen P Cramer
    Abstract:

    A new route to iron carbonyls has enabled synthesis of (57)Fe-labeled [NiFe] hydrogenase mimic (OC)3(57)Fe(pdt)Ni(dppe). Its study by nuclear resonance Vibrational Spectroscopy revealed Ni-(57)Fe vibrations, as confirmed by calculations. The modes are absent for [(OC)3(57)Fe(pdt)Ni(dppe)](+), which lacks Ni-(57)Fe bonding, underscoring the utility of the analyses in identifying metal-metal interactions.

  • a practical guide for nuclear resonance Vibrational Spectroscopy nrvs of biochemical samples and model compounds
    Methods of Molecular Biology, 2014
    Co-Authors: Hongxin Wang, Yoshitaka Yoda, E E Alp, Stephen P Cramer
    Abstract:

    Nuclear resonance Vibrational Spectroscopy (NRVS) has been used by physicists for many years. However, it is still a relatively new technique for bioinorganic users. This technique yields a Vibrational spectrum for a specific element, which can be easily interpreted. Furthermore, isotopic labeling allows for site-specific experiments. In this chapter we discuss how to access specific beamlines, what kind of equipment is used in NRVS and how the sample should be prepared and the data collected and analyzed.

  • inelastic x ray scattering of a transition metal complex fecl4 Vibrational Spectroscopy for all normal modes
    Inorganic Chemistry, 2013
    Co-Authors: Weibing Dong, Hongxin Wang, Eric Dowty, Marilyn M Olmstead, James C Fettinger, Jay C Nix, Hiroshi Uchiyama, Satoshi Tsutsui, Alfred Q R Baron, Stephen P Cramer
    Abstract:

    The tetraethylammonium salt of the transition-metal complex FeCl4 − has been examined using inelastic X-ray scattering (IXS) with 1.5 meV resolution (12 cm −1 ) at 21.747 keV. This sample serves as a feasibility test for more elaborate transition-metal complexes. The IXS spectra were compared with previously recorded IR, Raman, and nuclear resonant Vibrational Spectroscopy (NRVS) spectra, revealing the same normal modes but with less strict selection rules. Calculations with a previously derived Urey-Bradley force field were used to simulate the expected Q and orientation dependence of the IXS intensities. The relative merits of IXS, compared to other photon-based Vibrational spectros- copies such as NRVS, Raman, and IR, are discussed.

Stephen P Cramer - One of the best experts on this subject based on the ideXlab platform.

David Schilter - One of the best experts on this subject based on the ideXlab platform.

  • hydride bridge in nife hydrogenase observed by nuclear resonance Vibrational Spectroscopy
    Nature Communications, 2015
    Co-Authors: Hideaki Ogata, Frank Neese, Hongxin Wang, Tobias Kramer, David Schilter, Vladimir Pelmenschikov, Maurice Van Gastel, Thomas B Rauchfuss
    Abstract:

    The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the (57)Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique 'wagging' mode involving H(-) motion perpendicular to the Ni(μ-H)(57)Fe plane was studied using (57)Fe-specific nuclear resonance Vibrational Spectroscopy and density functional theory (DFT) calculations. On Ni(μ-D)(57)Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe-CO/CN bands. Spectra have been interpreted by comparison with Ni(μ-H/D)(57)Fe enzyme mimics [(dppe)Ni(μ-pdt)(μ-H/D)(57)Fe(CO)3](+) and DFT calculations, which collectively indicate a low-spin Ni(II)(μ-H)Fe(II) core for Ni-R, with H(-) binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe-H moieties in other important natural and synthetic catalysts.

  • Hydride bridge in [NiFe]-hydrogenase observed by nuclear resonance Vibrational Spectroscopy
    Nature Communications, 2015
    Co-Authors: Hideaki Ogata, Frank Neese, Hongxin Wang, Thomas B Rauchfuss, Tobias Kramer, David Schilter, Vladimir Pelmenschikov, Maurice Van Gastel, Leland B Gee, Aubrey D. Scott
    Abstract:

    Understanding the catalytic mechanism of redox-active hydrogenases is a key to efficient hydrogen production and consumption. Here, the authors use nuclear resonance Vibrational Spectroscopy to study [NiFe]-hydrogenase, and observe a bridging hydride structure in an EPR silent intermediate. The metabolism of many anaerobes relies on [NiFe]-hydrogenases, whose characterization when bound to substrates has proven non-trivial. Presented here is direct evidence for a hydride bridge in the active site of the ^57Fe-labelled fully reduced Ni-R form of Desulfovibrio vulgaris Miyazaki F [NiFe]-hydrogenase. A unique ‘wagging’ mode involving H^− motion perpendicular to the Ni( μ -H)^57Fe plane was studied using ^57Fe-specific nuclear resonance Vibrational Spectroscopy and density functional theory (DFT) calculations. On Ni( μ -D)^57Fe deuteride substitution, this wagging causes a characteristic perturbation of Fe–CO/CN bands. Spectra have been interpreted by comparison with Ni( μ -H/D)^57Fe enzyme mimics [(dppe)Ni( μ -pdt)( μ -H/D)^57Fe(CO)_3]^+ and DFT calculations, which collectively indicate a low-spin Ni( II )( μ -H)Fe( II ) core for Ni-R, with H^− binding Ni more tightly than Fe. The present methodology is also relevant to characterizing Fe–H moieties in other important natural and synthetic catalysts.

  • synthesis and Vibrational Spectroscopy of 57fe labeled models of nife hydrogenase first direct observation of a nickel iron interaction
    Chemical Communications, 2014
    Co-Authors: David Schilter, Hongxin Wang, Thomas B Rauchfuss, Vladimir Pelmenschikov, Yoshitaka Yoda, Leland B Gee, Florian Meier, Martin Kaupp, Stephen P Cramer
    Abstract:

    A new route to iron carbonyls has enabled synthesis of (57)Fe-labeled [NiFe] hydrogenase mimic (OC)3(57)Fe(pdt)Ni(dppe). Its study by nuclear resonance Vibrational Spectroscopy revealed Ni-(57)Fe vibrations, as confirmed by calculations. The modes are absent for [(OC)3(57)Fe(pdt)Ni(dppe)](+), which lacks Ni-(57)Fe bonding, underscoring the utility of the analyses in identifying metal-metal interactions.

Yoshitaka Yoda - One of the best experts on this subject based on the ideXlab platform.

Philipp Kukura - One of the best experts on this subject based on the ideXlab platform.

  • population controlled impulsive Vibrational Spectroscopy background and baseline free raman Spectroscopy of excited electronic states
    Journal of Physical Chemistry A, 2014
    Co-Authors: Torsten Wende, Matz Liebel, Christoph Schnedermann, Robert J Pethick, Philipp Kukura
    Abstract:

    We have developed the technique of population-controlled impulsive Vibrational Spectroscopy (PC-IVS) aimed at providing high-quality, background-free Raman spectra of excited electronic states and their dynamics. Our approach consists of a modified transient absorption experiment using an ultrashort (<10 fs) pump pulse with additional electronic excitation and control pulses. The latter allows for the experimental isolation of excited-state Vibrational coherence and, hence, Vibrational spectra. We illustrate the capabilities of PC-IVS by reporting the Raman spectra of well-established molecular systems such as the carotenoid astaxanthin and trans-stilbene and present the first excited-state Raman spectra of the retinal protonated Schiff base chromophore in solution. Our approach, illustrated here with impulsive Vibrational Spectroscopy, is equally applicable to transient and even multidimensional infrared and electronic spectroscopies to experimentally isolate spectroscopic signatures of interest.

  • broad band impulsive Vibrational Spectroscopy of excited electronic states in the time domain
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Matz Liebel, Philipp Kukura
    Abstract:

    We demonstrate that transient absorption Spectroscopy performed with an ultrashort pump pulse and a chirped, broad-band probe pulse is capable of recording full Vibrational spectra of excited electronic states in the time domain. The resulting spectra do not suffer from the nontrivial baselines and line shapes often encountered in frequency domain techniques and enable optimal and automated subtraction of background signatures. Probing the molecular dynamics continuously over a broad energy bandwidth makes it possible to confidently assign the Vibrational coherences to specific electronic states and suggests the existence of mode-specific absorption spectra reminiscent of resonance Raman intensity analysis. The first observation of the nominally forbidden one-photon ground to first excited electronic state transition in β-carotene demonstrates the high sensitivity of our approach. Our results provide a first glimpse of the immense potential of broad-band impulsive Vibrational Spectroscopy (BB-IVS) to stud...