Picosecond solvation dynamics—A potential viewer of DMSO—Water binary mixtures
TL;DR: This work has investigated the composition dependent anomalous behavior of dimethyl sulfoxide (DMSO)-water binary mixture by collecting the ultrafast solvent relaxation response around a well known solvation probe Coumarin 480 by using a femtosecond fluorescence up-conversion spectrometer.
Abstract: In this work, we have investigated the composition dependent anomalous behavior of dimethyl sulfoxide (DMSO)-water binary mixture by collecting the ultrafast solvent relaxation response around a well known solvation probe Coumarin 480 (C480) by using a femtosecond fluorescence up-conversion spectrometer. Recent molecular dynamics simulations have predicted two anomalous regions of DMSO-water binary mixture. Particularly, these studies encourage us to investigate the anomalies from experimental background. DMSO-water binary mixture has repeatedly given evidences of its dual anomalous nature in front of our systematic investigation through steady-state and time-resolved measurements. We have calculated average solvation times of C480 by two individual well-known methods, among them first one is spectral-reconstruction method and another one is single-wavelength measurement method. The results of both the methods roughly indicate that solvation time of C480 reaches maxima in the mole fraction of DMSO XD = 0.12–0.17 and XD = 0.27–0.35, respectively. Among them, the second region (XD = 0.27–0.35) is very common as most of the thermodynamic properties exhibit deviation in this range. Most probably, the anomalous solvation trend in this region is fully guided by the shear viscosity of the medium. However, the first region is the most interesting one. In this region due to formation of strongly hydrogen bonded 1DMSO:2H2O complexes, hydration around the probe C480 decreases, as a result of which solvation time increases.
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TL;DR: In infrared absorption spectroscopy of the S=O stretching mode combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen-bond populations in binary mixtures, finding evidence for three distinct regimes.
Abstract: Dimethyl sulfoxide (DMSO) disrupts the hydrogen-bond networks in water The widespread use of DMSO as a cosolvent, along with its unusual attributes, have inspired numerous studies Herein, infrared absorption spectroscopy of the S=O stretching mode combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen-bond populations in binary mixtures Singly H-bonded species are dominant at 10 mol %, due to strong DMSO-water interactions We found an unexpected increase in non-hydrogen-bonded DMSO near the eutectic point (ca 35 mol %) which also correlates with several abnormalities in the bulk solution properties We find evidence for three distinct regimes: 1) strong DMSO-water interactions ( 90 mol %) We propose a "step in" mechanism, which involves hydrogen bonding between water and the DMSO aggregate species
87 citations
TL;DR: In this paper, a solvent additive with high donor number was proposed to suppress the parasitic hydrogen evolution reaction (HER) in a flow-based Al-air battery with an outstanding energy density of 3106.04 Wh kg−1.
Abstract: Aqueous electrolyte is one of the most favored choices for various high-energy, low-cost and safe batteries. However, the undesired parasitic hydrogen evolution reaction (HER), especially on high reactive metal anodes, brought by aqueous electrolyte remains the development bottleneck of these batteries. Here, introducing solvents to manipulate the hydrogen-bond network of aqueous electrolyte is proposed to suppress the parasitic HER. Significantly, theoretical simulations and experimental characterizations demonstrate that donor number of the solvents could serve as a descriptor to ability of confining the free water and reducing the water activity. The solvent additive with high donor number exhibits remarkable suppression on the self-discharge and hydrogen evolution of Al anodes in alkaline electrolyte, which endows a flow-based Al-air battery with an outstanding energy density of 3106.04 Wh kg−1. The findings not only provide a guidance on the rational design of aqueous electrolyte but also expand the application of high-donor solvents.
25 citations
TL;DR: From temperature dependent anisotropy measurements, it is shown that aggregation of alcohol molecules increases with increase in temperature, and average solvation time of Coumarin 480 (C480) is calculated.
Abstract: In this article, we have investigated the anomalous behavior of two alcohol–water (tert-butyl alcohol (TBA)–water and ethanol–water) binary mixtures using femtosecond fluorescence upconversion technique. Recently, Gupta and Patey (Gupta, R.; Patey, G. N. J. Chem. Phys. 2012, 137, 034509(1)–034509(12)) have used four force fields to simulate TBA–water binary mixtures. Surprisingly, two of them do not identify any aggregation of TBA molecules. We have calculated average solvation time of Coumarin 480 (C480) using two different methods. Our results indicate slowdown in solvation time in the mole fraction ranges XT = 0.09–0.15, XT = 0.40–0.46 and XE = 0.06–0.08, XE = 0.20–0.25 for TBA–water and ethanol–water binary mixtures, respectively. Additionally, we have detected another anomalous region at XT ∼ 0.03. Slow solvation responses in the ranges XT = 0.40–0.46 and XE = 0.20–0.25 are probably due to the higher shear viscosity of the medium. However, XT = 0.09–0.15 and XE = 0.06–0.08 are the manifestation of ag...
25 citations
TL;DR: In this paper, infrared absorption spectroscopy of the S=O stretch combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen bond populations in binary mixtures.
Abstract: Dimethyl sulfoxide (DMSO) disrupts the hydrogen-bond networks in water. DMSO's widespread uses as a cosolvent, along with its unusual attributes, have inspired numerous studies. In this study, infrared absorption spectroscopy of the S=O stretch combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen bond populations in binary mixtures. Singly H-bonded species are dominant at 10 mol%, due to strong DMSO-water interactions. We found an unexpected increase in non-hydrogen-bonded DMSO near the eutectic point (~35 mol%) which also correlates with several abnormalities in the solution's bulk properties. We find evidence for three distinct regimes: 1. Strong DMSO-water interactions ( 90 mol%). We propose a "step in" mechanism, which involves hydrogen bonding between water and the DMSO aggregate species.
23 citations
TL;DR: This work uses ultrafast two-dimensional infrared spectroscopy to measure the H-bond dynamics of two probe molecules with different polarities, and suggests a previously unknown liquid environment, which is labelled "local bulk", in which despite the local heterogeneity, the ultrafast H- bond dynamics are similar to bulk water.
Abstract: Liquid–liquid phase separation is common in complex mixtures, but the behavior of nanoconfined liquids is poorly understood from a physical perspective. Dimethyl sulfoxide (DMSO) is an amphiphilic ...
23 citations
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2,210 citations
TL;DR: In this article, the authors used time-resolved emission measurements of the solute coumarin 153 (C153) to probe the time dependence of solvation in 24 common solvents at room temperature.
Abstract: Time-resolved emission measurements of the solute coumarin 153 (C153) are used to probe the time dependence of solvation in 24 common solvents at room temperature. Significant improvements in experimental time resolution ({approx}100 fs instrument response) as well as corresponding improvements in analysis methods provide confidence that all of the spectral evolution (including both the inertial and the diffusive parts of the response) are observed in these measurements. Extensive data concerning the steady-state solvatochromism of C153, coupled to an examination of the effects of vibrational relaxation, further demonstrate that the spectral dynamics being observed accurately monitor the dynamics of nonspecific solvation. Comparisons to theoretical predictions show that models based on the dielectric response of the pure solvent provide a semiquantitative understanding of the dynamics observed. 156 refs., 26 figs., 5 tabs.
1,909 citations
TL;DR: In this paper, a probe molecule coumarin 153 (Cu153) and picosecond spectroscopic techniques were used to examine the solvation dynamics in polar liquids and showed that the frequency of the electronic spectrum of this probe provides a convenient measure of solvation energetics.
Abstract: Solvation dynamics in polar liquids have been examined using the probe molecule coumarin 153 (Cu153) and picosecond spectroscopic techniques. Steady‐state absorption and fluorescence spectra of Cu153 as a function of solvent show that the frequency of the electronic spectrum of this probe provides a convenient measure of solvation energetics. Both nonspecific dipolar and to a smaller degree H‐bonding solute–solvent interactions are involved. Time‐correlated single photon counting was used to observe time‐dependent shifts of the fluorescence spectrum of Cu153 in a variety of alcohols, propylene carbonate, and N‐methylpropionamide solvents as a function of temperature. These time‐dependent spectral shifts provide a direct measure of the time dependence of the solvation process. Theoretical models that treat the solvent as a dielectric continuum do not adequately account for the observed solvation dynamics. In the solvents studied, such theories predict a single exponential shift of the fluorescence spectrum...
1,127 citations
TL;DR: In this paper, photophysical parameters have been determined for coumarin laser dyes in a variety of organic solvents, water, and mixed media, showing that substituent influences resulted in enlarged excited-state dipole moments for the fluorescent state.
Abstract: Photophysical parameters have been determined for coumarin laser dyes in a variety of organic solvents, water, and mixed media. The response of fluorescence emission yield and lifetime to changes in solvent polarity was a sensitive function of coumarin substitution pattern. Most important were substituent influences which resulted in enlarged excited-state dipole moments for the fluorescent state. For dyes displaying sharp reductions in emission yield and lifetime with increased solvent polarity, protic media and particularly water were most effective in inhibiting fluorescence. The temperature dependence of emission yield and lifetime was measured for two solvent-sensitive dyes in acetonitrile and in a highly viscous solvent, glycerol. The quenching of coumarin fluorescence by oxygen for dyes with lifetimes > 2 ns was also observed. The dominant photophysical features for coumarin dyes are discussed in terms of emission from an intramolecular charge-transfer (ICT) excited state and an important nonradiative decay path involving rotation of the amine functionality (7-position) leading to a twisted intramolecular CT state (TICT). The role of excited-state bond orders involving the rotating group in determining the importance of interconversions of the type ICT ..-->.. TICT is discussed. 73 references, 1 figure, 3 tables.
1,028 citations
01 Oct 1983
TL;DR: In this paper, photophysical parameters have been determined for coumarin laser dyes in a variety of organic solvents, water, and mixed media, showing that substituent influences resulted in enlarged excited-state dipole moments for the fluorescent state.
Abstract: Photophysical parameters have been determined for coumarin laser dyes in a variety of organic solvents, water, and mixed media. The response of fluorescence emission yield and lifetime to changes in solvent polarity was a sensitive function of coumarin substitution pattern. Most important were substituent influences which resulted in enlarged excited-state dipole moments for the fluorescent state. For dyes displaying sharp reductions in emission yield and lifetime with increased solvent polarity, protic media and particularly water were most effective in inhibiting fluorescence. The temperature dependence of emission yield and lifetime was measured for two solvent-sensitive dyes in acetonitrile and in a highly viscous solvent, glycerol. The quenching of coumarin fluorescence by oxygen for dyes with lifetimes > 2 ns was also observed. The dominant photophysical features for coumarin dyes are discussed in terms of emission from an intramolecular charge-transfer (ICT) excited state and an important nonradiative decay path involving rotation of the amine functionality (7-position) leading to a twisted intramolecular CT state (TICT). The role of excited-state bond orders involving the rotating group in determining the importance of interconversions of the type ICT ..-->.. TICT is discussed. 73 references, 1 figure, 3 tables.
896 citations