Vibrational dynamics of the CN stretching mode of [Ru(CN)6]4− in D2O studied by nonlinear infrared spectroscopy

Tayama, Jumpei; Banno, Motohiro; Ohta, Kaoru; Tominaga, Kazuhiro

doi:10.1007/s11433-010-3218-8

Cited by 7 publications

(8 citation statements)

References 29 publications

(32 reference statements)

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“…The role of electric field fluctuations in the dephasing dynamics of charged species dissolved in polar solvents has been widely studied to understand the role of solvent fluctuations in chemistry and biology. There is growing experimental evidence that the collective dynamics of the solvent around small ionic solutes play the biggest role in determining the amplitudes and time scales of the vibrational frequency fluctuations of the solute. ,,− Tominaga and co-workers have performed systematic studies of measuring the FFCFs of the cyanide, nitrosyl, and azide stretching vibrations in ionic solutes dissolved in aqueous solvents. ,,− Their studies find a common time scale ranging from 1 to 1.5 ps for the frequency fluctuations for various ions regardless of the vibration being studied. This similar time scale has been obtained in experimental studies of the OH(OD) stretch of HOD in D 2 O(H 2 O). ,,, Molecular dynamics simulations have been used to obtain the FFCF of the azide stretch in D 2 O and the OH(OD) stretch of HOD in D 2 O(H 2 O). ,, The simulation studies have shown that the experimentally measured picosecond vibrational dephasing dynamics are driven by electric field fluctuations originating from collective reorganization of the hydrogen bonding network.…”

Section: Discussionmentioning

confidence: 99%

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an Fe^II Complex Revealed by 2D IR Spectroscopy

et al. 2013

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The vibrational dephasing dynamics of the nitrosyl stretching vibration (ν(NO)) in sodium nitroprusside (SNP, Na2[Fe(CN)5NO]·2H2O) are investigated using two-dimensional infrared (2D IR) spectroscopy. The ν(NO) in SNP acts as a model system for the nitrosyl ligand found in metalloproteins which play an important role in the transportation and detection of nitric oxide (NO) in biological systems. We perform a 2D IR line shape study of the ν(NO) in the following solvents: water, deuterium oxide, methanol, ethanol, ethylene glycol, formamide, and dimethyl sulfoxide. The frequency of the ν(NO) exhibits a large vibrational solvatochromic shift of 52 cm(-1), ranging from 1884 cm(-1) in dimethyl sulfoxide to 1936 cm(-1) in water. The vibrational anharmonicity of the ν(NO) varies from 21 to 28 cm(-1) in the solvents used in this study. The frequency-frequency correlation functions (FFCFs) of the ν(NO) in SNP in each of the seven solvents are obtained by fitting the experimentally obtained 2D IR spectra using nonlinear response theory. The fits to the 2D IR line shape reveal that the spectral diffusion time scale of the ν(NO) in SNP varies from 0.8 to 4 ps and is negatively correlated with the empirical solvent polarity scales. We compare our results with the experimentally determined FFCFs of other charged vibrational probes in polar solvents and in the active sites of heme proteins. Our results suggest that the vibrational dephasing dynamics of the ν(NO) in SNP reflect the fluctuations of the nonhomogeneous electric field created by the polar solvents around the nitrosyl and cyanide ligands. The solute solvent interactions occurring at the trans-CN ligand are sensed through the π-back-bonding network along the Fe-NO bond in SNP.

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Section: Discussionmentioning

confidence: 99%

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an Fe^II Complex Revealed by 2D IR Spectroscopy

et al. 2013

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“…These dynamical quantities were investigated by the pump–probe or transient grating technique in the IR region, which are also third-order nonlinear techniques. In Table , we summarize the results from the FTIR measurements of the probe molecule together with those of the population relaxation and orientational relaxation for methanol and aqueous solutions at room temperature. − The results for the temperature dependence on N 3 – in aqueous solutions can be found in ref .…”

Section: Three-pulse Ir Photon Echo Experiments In Aqueous Solutionsmentioning

confidence: 99%

“…We have studied the vibrational frequency fluctuation of probes, such as triatomic ions and metal complexes with CN or NO ligands, in various hydrogen-bonding solvents, including water droplets in reverse micelles. − The concentrations of the solutes were 20–60 mM, which are low enough to ensure that the solvation shells do not overlap. Figure a shows the three-pulse IR photon echo signals of N 3 – in D 2 O at 303 K under all-parallel polarization conditions.…”

Section: Three-pulse Ir Photon Echo Experiments In Aqueous Solutionsmentioning

confidence: 99%

Vibrational Frequency Fluctuation of Ions in Aqueous Solutions Studied by Three-Pulse Infrared Photon Echo Method

et al. 2012

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In liquid water, hydrogen bonds form three-dimensional network structures, which have been modeled in various molecular dynamics simulations. Locally, the hydrogen bonds continuously form and break, and the network structure continuously fluctuates. In aqueous solutions, the water molecules perturb the solute molecules, resulting in fluctuations of the electronic and vibrational states. These thermal fluctuations are fundamental to understanding the activation processes in chemical reactions and the function of biopolymers. In this Account, we review studies of the vibrational frequency fluctuations of solute molecules in aqueous solutions using three-pulse infrared photon echo experiments. For comparison, we also briefly describe dynamic fluorescence Stokes shift experiments for investigating solvation dynamics in water. The Stokes shift technique gives a response function, which describes the energy relaxation in the nonequilibrium state and corresponds to the transition energy fluctuation of the electronic state at thermal equilibrium in linear response theorem. The dielectric response of water in the megahertz to terahertz frequency region is a key physical quantity for understanding both of these frequency fluctuations because of the influence of electrostatic interactions between the solute and solvent. We focus on the temperature dependence of the three experiments to discuss the molecular mechanisms of both the frequency fluctuations in aqueous solutions. We used a biexponential function with sub-picosecond and picosecond time constants to characterize the time-correlation functions of both the vibrational and electronic frequency fluctuations. We focus on the slower component, with time constants of 1-2 ps for both the frequency fluctuations at room temperature. However, the temperature dependence and isotope effect for the time constants differ for these two types of fluctuations. The dielectric interactions generally describe the solvation dynamics of polar solvents, and hydrodynamic theory can describe the slow component for the electronic states. Compared with the slow component of the solvation dynamics, however, the picosecond component for the vibrational frequency fluctuations is less sensitive to temperature. Therefore, the slow component of the vibrational frequency fluctuation is determined by different underlying dynamics, which are important for the solvation dynamics of the electronic state. The time constant for the picosecond component for the vibrational frequency fluctuation does not significantly depend on the solute. We propose that the vibrational frequency fluctuates because of the constant structural changes in the hydrogen-bonding network of water molecules around the solute.

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“…3 Furthermore, we have studied the spectral diffusion processes of the antisymmetric stretching modes of OCN À and SCN À in methanol, and the CN stretching modes of metal complexes in water by using three-pulse IR photon echo methods. [28][29][30][31][32] We have recently reported a detailed analysis of the temperature dependence of the vibrational dynamics of azide in water. 33 In addition to studies of simple ion-solvent systems, the antisymmetric stretching modes of azide and thiocyanate have attracted much attention because these modes are useful IR probes for studying the fluctuations of the surrounding environment in peptides and proteins.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast vibrational dynamics of SCN− and N3− in polar solvents studied by nonlinear infrared spectroscopy

Ohta

Tayama

Tominaga

2012

Phys. Chem. Chem. Phys.

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In this paper, we report on our investigation into the vibrational dynamics of the antisymmetric stretching modes of SCN(-) and N(3)(-) in several polar solvents. We used an infrared (IR) pump-probe method to study orientational relaxation processes. In two aprotic solvents (N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO)), the anisotropy decay shows a bimodal feature, whereas in other solvents the anisotropy decay can be fitted well by a single exponential function. We consider that the relative contribution of fast-decaying components is smaller in the other solvents than in DMF and DMSO. We discuss the possible origins of the different anisotropy decay behavior in different solvents. From the three-pulse IR photon echo measurements for SCN(-) and N(3)(-), we found that the time-correlation functions (TCFs) of vibrational frequency fluctuations decay on two different time scales, one of which is less than 100 fs and the other is approximately 3-6 ps. In aprotic solvents, the fast-decaying components of the TCFs on a <100 fs time scale play an important role in the vibrational frequency fluctuation, although the contribution of collective solvent reorganization in aprotic solvents was clearly observed to have small amplitudes. On the other hand, we found that the amplitude of components that decay in a few picoseconds and/or the constant offset of the TCF in protic solvents is relatively large compared with that in aprotic solvents. With the formation and dissociation of hydrogen bonds between ion solute and solvent molecules, the spectra of different solvated species are exchanged with each other and merged into one band. We considered that this exchange may be an origin of slow-decaying components of the TCFs and that the decay of the TCFs corresponds to the time scales of the exchange for protic solvents such as formamide. The mechanism of vibrational frequency fluctuations for the antisymmetric stretching modes of SCN(-) and N(3)(-) is discussed in terms of the difference between protic and aprotic solvents.

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Vibrational dynamics of the CN stretching mode of [Ru(CN)6]4− in D2O studied by nonlinear infrared spectroscopy

Cited by 7 publications

References 29 publications

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an Fe^II Complex Revealed by 2D IR Spectroscopy

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an Fe^II Complex Revealed by 2D IR Spectroscopy

Vibrational Frequency Fluctuation of Ions in Aqueous Solutions Studied by Three-Pulse Infrared Photon Echo Method

Ultrafast vibrational dynamics of SCN− and N3− in polar solvents studied by nonlinear infrared spectroscopy

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Vibrational dynamics of the CN stretching mode of [Ru(CN)6]4− in D2O studied by nonlinear infrared spectroscopy

Cited by 7 publications

References 29 publications

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an FeII Complex Revealed by 2D IR Spectroscopy

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an FeII Complex Revealed by 2D IR Spectroscopy

Vibrational Frequency Fluctuation of Ions in Aqueous Solutions Studied by Three-Pulse Infrared Photon Echo Method

Ultrafast vibrational dynamics of SCN− and N3− in polar solvents studied by nonlinear infrared spectroscopy

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Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an Fe^II Complex Revealed by 2D IR Spectroscopy

Effect of Solvent Polarity on the Vibrational Dephasing Dynamics of the Nitrosyl Stretch in an Fe^II Complex Revealed by 2D IR Spectroscopy