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Zhou D, Zhao B, Bai Y, Mukherjee S, Liu J, Bian H, Fang Y. Exploring the Structure and Complexation Dynamics of Azide Anion Recognition by Calix[4]pyrroles in Solution. J Phys Chem Lett 2022; 13:669-675. [PMID: 35023744 DOI: 10.1021/acs.jpclett.1c03962] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The structure and anion recognition dynamics between calix[4]pyrroles and azide (N3-) anions in the form of its TBA+ and Na+ salts were investigated in dimethyl sulfoxide solutions by Fourier transform infrared (FTIR) spectroscopy and ultrafast IR spectroscopy. Vibrational energy redistribution of the N3- anion in the complex is accelerated through hydrogen bonding interactions with the N-H proton of the receptor. Rotational dynamics of the bound N3- is greatly restricted, demonstrating a distinct countercation effect. The detailed binding modes of N3- with the receptor were further evaluated by the density functional theoretical (DFT) calculations and nuclear magnetic resonance (NMR) spectroscopy. All of these measurements support the notion that the calix[4]pyrroles are capable of capturing the azide anion in solution. However, the calix[4]pyrroles may not necessarily undergo a conformational change to a cone-like geometry when they bind to the azide anion in the solution.
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Affiliation(s)
- Dexia Zhou
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
| | - Boxu Zhao
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
| | - Yimin Bai
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
| | - Somnath Mukherjee
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
| | - Jing Liu
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
| | - Hongtao Bian
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
| | - Yu Fang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an, 710119, China
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Hong J, Zhou DX, Hao HX, Zhao M, Bian HT. Ultrafast infrared spectroscopic study of microscopic structural dynamics in pH stimulus-responsive hydrogels. CHINESE J CHEM PHYS 2020. [DOI: 10.1063/1674-0068/cjcp2006096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Jian Hong
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
| | - De-xia Zhou
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
| | - Hong-xing Hao
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
| | - Min Zhao
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
| | - Hong-tao Bian
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi’an 710119, China
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Straub S, Stubbe J, Lindner J, Sarkar B, Vöhringer P. Vibrational Relaxation Dynamics of an Azido–Cobalt(II) Complex from Femtosecond UV-Pump/MIR-Probe Spectroscopy and Model Simulations with Ab Initio Anharmonic Couplings. Inorg Chem 2020; 59:14629-14642. [DOI: 10.1021/acs.inorgchem.0c00553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Steffen Straub
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115 Bonn, Germany
| | - Jessica Stubbe
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/34, 14195 Berlin, Germany
| | - Jörg Lindner
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115 Bonn, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/34, 14195 Berlin, Germany
- Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Peter Vöhringer
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115 Bonn, Germany
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4
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Zhou D, Wei Q, Wang S, Li X, Bian H. Counterion Effect on Vibrational Relaxation and the Rotational Dynamics of Interfacial Water and an Anionic Vibrational Probe in the Confined Reverse Micelles Environment. J Phys Chem Lett 2019; 10:176-182. [PMID: 30582817 DOI: 10.1021/acs.jpclett.8b03389] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vibrational relaxation and the rotational dynamics of water molecules encapsulated in reverse micelles (RMs) have been investigated by ultrafast infrared (IR) spectroscopy and two-dimensional IR (2D IR) spectroscopy. By changing the counterion of the hydrophilic headgroup in the RMs formed by Aerosol-OT (AOT) from Na+ to K+, Cs+ and Ca2+, we could determine the specific counterion effects on the rotational dynamics of water molecules. The orientational relaxation time constant of water decreases in the order Ca2+ > Na+ > K+ > Cs+. The SCN- anionic probe and counterion can form ion pairs at the interfacial region of the RMs. The rotational dynamics of SCN- anion significantly decreases because of the synergistic effects of confinement and the surface interactions in the interfacial region of the RMs. The results can provide a new understanding of the cationic Hofmeister effect at the molecular level observed in biological studies.
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Affiliation(s)
- Dexia Zhou
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Qianshun Wei
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Shuyan Wang
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Xiaoqian Li
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
| | - Hongtao Bian
- Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering , Shaanxi Normal University , Xi'an , 710119 , China
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5
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Singha D, Sahu DK, Sahu K. Anomalous Spectral Modulation of 4-Aminophthalimide inside Acetonitrile/AOT/ n-Heptane Microemulsion: New Insights on Reverse Micelle to Bicontinuous Microemulsion Transition. J Phys Chem B 2018; 122:6966-6974. [PMID: 29901391 DOI: 10.1021/acs.jpcb.8b03901] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The behavior of acetonitrile/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/ n-heptane microemulsion, whether it remains as reverse micelle (RM) or bicontinuous microemulsion (BMC), has been controversial and even termed as a "problem system". Herein, we investigate the microemulsion using spectral and dynamical responses of a hydrophilic solvatochromic fluorophore 4-aminophthalimide (4-AP) at different ws values (=[acetonitrile]/[AOT]). Interestingly, we found that emission parameters of 4-AP within the microemulsion vary differently at low and high ws regimes. The quantum yield (ϕf) and lifetime (τf) of 4-AP first increase up to ws = ∼1 and, thereafter, decrease upon a further increase in the ws values. The emission maximum of 4-AP significantly shifts to a higher wavelength from 445 nm at ws = 0 to 475 nm at ws = 8. Interestingly, unlike aqueous RMs, the emission maximum at ws = 1 matches with the emission maximum in neat acetonitrile and the emission maximum shifts to even longer wavelength at a higher ws. Steady-state anisotropy also shows a break around ws = 1; anisotropy decreases very sharply from ws = 0 to 1 and, thereafter, remains nearly constant. Solvation dynamics becomes progressively faster with an increase in the acetonitrile content only in the low ws regimes but remains almost independent of ws after ws > 2. All of the results collectively indicate that the morphology of the microemulsion may change at an intermediate ws (∼1); below this, the system behaves like reverse micelles, and above this, the system may remain as BMC. The conjecture was further supported by dynamic light scattering measurements, where we observed a gradual increment of the average size at the low acetonitrile content (up to ws = 1) but, thereafter, the size distribution becomes multimodal and sizes cannot be estimated correctly.
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Affiliation(s)
- Debabrata Singha
- Department of Chemistry , Indian Institute of Technology Guwahati , Guwahati 781039 , Assam , India
| | - Dillip Kumar Sahu
- Department of Chemistry , Indian Institute of Technology Guwahati , Guwahati 781039 , Assam , India
| | - Kalyanasis Sahu
- Department of Chemistry , Indian Institute of Technology Guwahati , Guwahati 781039 , Assam , India
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7
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Compton R, Gerardi HK, Weidinger D, Brown DJ, Dressick WJ, Heilweil EJ, Owrutsky JC. Spectra and relaxation dynamics of the pseudohalide (PS) vibrational bands for Ru(bpy)2(PS)2 complexes, PS=CN, NCS and N3. Chem Phys 2013. [DOI: 10.1016/j.chemphys.2012.11.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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8
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Locations of methanol in methanol-containing AOT reverse micelles revealed by photophysics of IR125. J Photochem Photobiol A Chem 2013. [DOI: 10.1016/j.jphotochem.2012.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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9
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Correa NM, Silber JJ, Riter RE, Levinger NE. Nonaqueous Polar Solvents in Reverse Micelle Systems. Chem Rev 2012; 112:4569-602. [DOI: 10.1021/cr200254q] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N. Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Juana J. Silber
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Ruth E. Riter
- Department of Chemistry, Agnes Scott College, Decatur, Georgia 30030-3770, United
States
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872,
United States
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Olschewski M, Knop S, Lindner J, Vöhringer P. Vibrational relaxation of azide ions in liquid-to-supercritical water. J Chem Phys 2011; 134:214504. [DOI: 10.1063/1.3598108] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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11
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Houchins C, Weidinger D, Owrutsky JC. Vibrational Spectroscopy and Dynamics of the Hydrazoic and Isothiocyanic Acids in Water and Methanol. J Phys Chem A 2010; 114:6569-74. [DOI: 10.1021/jp102397b] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Cassidy Houchins
- Chemistry Division, Code 6111, U.S. Naval Research Laboratory, Washington, D.C. 20375-5342
| | - Daniel Weidinger
- Chemistry Division, Code 6111, U.S. Naval Research Laboratory, Washington, D.C. 20375-5342
| | - Jeffrey C. Owrutsky
- Chemistry Division, Code 6111, U.S. Naval Research Laboratory, Washington, D.C. 20375-5342
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12
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Abstract
Recent advances in ultrafast laser technology have spurred investigations of microheterogeneous solutions. In particular, researchers have explored details of reverse micelles (RMs), which present isolated droplets of polar solvent sequestered from a continuous nonpolar phase by a surfactant layer. This review explores recent studies utilizing a variety of ultrafast laser techniques to uncover details about structure and dynamics in various RMs. Using ultrafast vibrational spectroscopy, researchers have probed hydrogen-bond dynamics and vibrational energy relaxation in RMs. These studies have developed our understanding of reverse micellar structure, identifying varying water environments in the RMs. In a plethora of experiments employing probe molecules, researchers have explored the confined environment presented by RMs and their impact on a range of chemical reactions. These studies have shown that confinement, rather than the specific interactions with surfactants, is an important factor determining the impact of the reverse micellar environment on the chemistry.
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Affiliation(s)
- Nancy E Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
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13
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14
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Setua P, Seth D, Sarkar N. To probe the structure of methanol and Aerosol OT (AOT) in AOT reverse micelles by FTIR measurements. Phys Chem Chem Phys 2009; 11:8913-22. [DOI: 10.1039/b818021k] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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15
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Morales CM, Thompson WH. Simulations of Infrared Spectra of Nanoconfined Liquids: Acetonitrile Confined in Nanoscale, Hydrophilic Silica Pores. J Phys Chem A 2008; 113:1922-33. [DOI: 10.1021/jp8072969] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Ward H. Thompson
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045
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16
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Choi JH, Oh KI, Cho M. Azido-derivatized compounds as IR probes of local electrostatic environment: Theoretical studies. J Chem Phys 2008; 129:174512. [DOI: 10.1063/1.3001915] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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17
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Chieffo LR, Shattuck JT, Pinnick E, Amsden JJ, Hong MK, Wang F, Erramilli S, Ziegler LD. Nitrous Oxide Vibrational Energy Relaxation Is a Probe of Interfacial Water in Lipid Bilayers. J Phys Chem B 2008; 112:12776-82. [DOI: 10.1021/jp8012283] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Logan R. Chieffo
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - Jeffrey T. Shattuck
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - Eric Pinnick
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - Jason J. Amsden
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - M. K. Hong
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - Feng Wang
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - Shyamsunder Erramilli
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
| | - Lawrence D. Ziegler
- Department of Chemistry, Department of Physics, Department of Biomedical Engineering and the Photonics Center, Boston University, 590 Commonwealth Avenue, Boston, MA 02215
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18
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Owrutsky JC, Pomfret MB, Barton DJ, Kidwell DA. Fourier transform infrared spectroscopy of azide and cyanate ion pairs in AOT reverse micelles. J Chem Phys 2008; 129:024513. [DOI: 10.1063/1.2952522] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Mitchell-Koch KR, Thompson WH. Infrared spectra of a model phenol-amine proton transfer complex in nanoconfined CH3Cl. J Phys Chem B 2008; 112:7448-59. [PMID: 18517239 DOI: 10.1021/jp076714e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The vibrational spectra of a model phenol-amine proton transfer complex dissolved in CH3Cl solvent confined in a 12 A radius spherical hydrophobic cavity were calculated using mixed quantum-classical molecular dynamics simulations. The reaction free energy of the proton transfer complex was varied in order to explore the contributions to the vibrational absorption band from product and reactant species. The vibrational spectra of the model proton transfer complex resulted in motionally narrowed spectral linewidths with two distinct peaks for products and reactants in cases where the system undergoes chemical exchange. It was found that the n=1 and n=2 vibrational excited states combine to form diabatic states such that the spectra have contributions from both n=0 --> n=1 and n=0 --> n=2 transitions. A strong relationship between the instantaneous vibrational frequency and a collective solvent coordinate was found that assists in understanding the origin of the spectral features.
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20
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Morales CM, Thompson WH. Umbrella sampling of solute vibrational line shifts in mixed quantum-classical molecular dynamics simulations. J Phys Chem B 2008; 112:313-20. [PMID: 18081335 DOI: 10.1021/jp075038d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An umbrella sampling approach for vibrational frequency line shifts is presented. The technique allows for efficient sampling of the solvent configurations corresponding to frequency shifts of a solute in mixed quantum-classical simulations. The approach is generally applicable and can also be used within traditional perturbation theory calculations of frequency shifts. It is particularly useful in the extraction of detailed mechanistic information about the solute-solvent interactions giving rise to the frequency shifts. The method is illustrated by application to the simple I2 in a liquid Xe system, and the advantages are discussed.
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21
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Li S, Schmidt JR, Piryatinski A, Lawrence CP, Skinner JL. Vibrational spectral diffusion of azide in water. J Phys Chem B 2007; 110:18933-8. [PMID: 16986886 DOI: 10.1021/jp057568k] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Vibrational spectral diffusion denotes the time-dependent fluctuations of a solute's vibrational frequencies due to local environmental dynamics. Vibrational line shapes are weakly sensitive to spectral diffusion, whereas three-pulse vibrational echoes are much more sensitive. We report here on theoretical studies of spectral diffusion of the asymmetric stretch of the azide anion in heavy water. We run a classical molecular dynamics simulation of rigid azide in rigid water, and at every time step we calculate the azide's anharmonic asymmetric stretch frequency using an optimized quantum mechanics/molecular mechanics method developed earlier. This generates a frequency trajectory, which we use to calculate the absorption line shape and integrated three-pulse echo intensity. Our results for both the line width and the integrated echo intensity are in excellent agreement with experiment. Our calculated frequency time-correlation function is in excellent agreement with experiment for long times (greater than 250 fs) but differs considerably from experiment at short times; our theoretical correlation function has a very pronounced oscillation, presumably due to intermolecular azide-water hydrogen-bond stretching dynamics.
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Affiliation(s)
- Shuzhou Li
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA
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22
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Seth D, Chakraborty A, Setua P, Sarkar N. Interaction of ionic liquid with water with variation of water content in 1-butyl-3-methyl-imidazolium hexafluorophosphate ([bmim][PF6])/TX-100/water ternary microemulsions monitored by solvent and rotational relaxation of coumarin 153 and coumarin 490. J Chem Phys 2007; 126:224512. [PMID: 17581068 DOI: 10.1063/1.2736378] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The interaction of water with room temperature ionic liquid (RTIL) [bmim][PF6] has been studied in [bmim][PF6]/TX-100/water ternary microemulsions by solvent and rotational relaxation of coumarin 153 (C-153) and coumarin 490 (C-490). The rotational relaxation and average solvation time of C-153 and C-490 gradually decrease with increase in water content of the microemulsions. The gradual increase in the size of the microemulsion with increase in w0 (w0=[water]/[surfactant]) is evident from dynamic light scattering measurements. Consequently the mobility of the water molecules also increases. In comparison to pure water the retardation of solvation time in the RTIL containing ternary microemulsions is very less. The authors have also reported the solvation time of C-490 in neat [bmim][PF6]. The solvation time of C-490 in neat [bmim][PF6] is bimodal with time constants of 400 ps and 1.10 ns.
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Affiliation(s)
- Debabrata Seth
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, West Bengal, India
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23
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Michaels MA, Sherwood S, Kidwell M, Allsbrook MJ, Morrison SA, Rutan SC, Carpenter EE. Quantitative model for prediction of hydrodynamic size of nonionic reverse micelles. J Colloid Interface Sci 2007; 311:70-6. [PMID: 17391691 DOI: 10.1016/j.jcis.2007.02.085] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Revised: 02/20/2007] [Accepted: 02/22/2007] [Indexed: 11/15/2022]
Abstract
The sizes of nonionic reverse micelles were investigated as a function of the molecular structure of the surfactant, the type of oil, the total concentration of surfactant [NP], the ratio of surfactant to total surfactant (r), the water to surfactant molar ratio (omega), temperature, salt concentration, and polar phase. The basis of our investigation was a mixture of nonylphenol polyethoxylates--NP4 and NP7, various polar phases, and several oils. Micelle sizes were determined using dynamic light scattering (DLS). A central composite experimental design was used to quantitatively model micelle size as a function of omega, surfactant concentration, and r. The model has demonstrated the capability of predicting the mean diameter of micelles from 4 to 13 with a precision of +/-2 nm as measured by DLS. This quantitative correlation between the size of reverse micelles and the synthetic variables provides the foundation for choosing experimental conditions to control reverse micelle size. In turn, this allows control of the size of nanoparticles synthesized within them.
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Affiliation(s)
- M A Michaels
- Department of Chemistry, Virginia Commonwealth University, Richmond, 1001 West Main Street, Richmond, VA 23284, USA
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24
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Morales CM, Thompson WH. Mixed Quantum-Classical Molecular Dynamics Analysis of the Molecular-Level Mechanisms of Vibrational Frequency Shifts. J Phys Chem A 2007; 111:5422-33. [PMID: 17580980 DOI: 10.1021/jp071656i] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A detailed analysis of the origins of vibrational frequency shifts of diatomic molecules (I2 and ICl) in a rare gas (Xe) liquid is presented. Specifically, vibrationally adiabatic mixed quantum-classical molecular dynamics simulations are used to obtain the instantaneous frequency shifts and correlate the shifts to solvent configurations. With this approach, important mechanistic questions are addressed, including the following: How many solvent atoms determine the frequency shift? What solvent atom configurations lead to blue shifts, and which lead to red shifts? What is the effect of solute asymmetry? The mechanistic analysis can be generally applied and should be useful in understanding what information is provided by infrared and Raman spectra about the environment of the probed vibrational mode.
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25
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Sando GM, Dahl K, Owrutsky JC. Vibrational Spectroscopy and Dynamics of Azide Ion in Ionic Liquid and Dimethyl Sulfoxide Water Mixtures. J Phys Chem B 2007; 111:4901-9. [PMID: 17388412 DOI: 10.1021/jp067143d] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Steady-state and time-resolved infrared spectroscopy of the azide (N(3)-) anion has been used to characterize aqueous mixtures both with the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF(4)]) and with dimethyl sulfoxide (DMSO). In the DMSO-water mixtures, two anion vibrational bands are observed for low water mole fractions (0 > X(w) > 0.25), which indicates a heterogeneous ion solvation environment. The band at 2000 cm(-1) observed for neat DMSO does not shift but decreases in amplitude as the amount of water is increased. Another band appears at slightly higher frequency at low X(w) (=0.05). As the amount of water is increased, this band shifts to higher frequency and becomes stronger and is attributed to azide with an increasing degree of hydration. At intermediate and high X(w), a single band is observed that shifts almost linearly with water mole fraction toward the bulk water value. The heterogeneity is evident from the infrared pump-probe studies in which the decay times depend on probe frequency at low mole fraction. For the azide spectra in IL-water mixtures, a single azide band is observed for each mole fraction mixture. The azide band shifts almost linearly with mole fraction, indicating nearly ideal mixing behavior. As with the DMSO-water mixtures, the time-resolved IR decay times are probe-frequency-dependent at low mole fraction, again indicating heterogeneous solvation. In both the DMSO and IL mixtures with water, the relaxation times are slower than would be expected from ideal mixing, suggesting that vibrational relaxation of azide is more sensitive than its vibrational frequency to the solvent structure. The results are discussed in terms of preferential solvation and the degree to which the azide shift and vibrational relaxation depend on the degree of water association in the mixtures.
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Affiliation(s)
- Gerald M Sando
- U.S. Naval Research Laboratory, Washington, District of Columbia 20375-5342, USA
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Chakraborty A, Seth D, Setua P, Sarkar N. Dynamics of Solvent and Rotational Relaxation of Glycerol in the Nanocavity of Reverse Micelles. J Phys Chem B 2006; 110:5359-66. [PMID: 16539469 DOI: 10.1021/jp056650c] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The dynamics of solvent and rotational relaxation of Coumarin 480 and Coumarin 490 in glycerol containing bis-2-ethyl hexyl sulfosuccinate sodium salt (AOT) reverse micelles have been investigated with steady-state and time-resolved fluorescence spectroscopy. We observed slower solvent relaxation of glycerol confined in the nanocavity of AOT reverse micelles compared to that in pure glycerol. However, the slowing down in the solvation time on going from neat glycerol to glycerol confined reverse micelles is not comparable to that on going from pure water or acetonitrile to water or acetonitrile confined AOT reverse micellar aggregates. While solvent relaxation times were found to decrease with increasing glycerol content in the reverse micellar pool, rotational relaxation times were found to increase with increase in glycerol content.
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Affiliation(s)
- Anjan Chakraborty
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721 302, WB, India
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Benjamin I. Theoretical Studies of Solute Vibrational Energy Relaxation at Liquid Interfaces. J Phys Chem B 2006; 110:9375-82. [PMID: 16686479 DOI: 10.1021/jp056420y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recent advances in the theoretical understanding of solute vibrational energy relaxation at liquid interfaces and surfaces are described. Non-equilibrium molecular dynamics simulations of the relaxation of an initially excited solute molecule are combined with equilibrium force autocorrelation calculations to gain insight into the factors that influence the vibrational relaxation rate. Diatomic and triatomic nonpolar, polar, and ionic solute molecules adsorbed at the liquid/vapor interface of several liquids as well as at the water/CCl(4) liquid/liquid interface are considered. In general, the vibrational relaxation rate is significantly slower (a factor of 3 to 4) at the liquid/vapor and liquid/liquid interface than in the bulk due to the reduced density, which gives rise to a reduced contribution of the repulsive solvent-solute forces on the vibrational mode. The surface effects on the ionic solutes are much smaller (50% or less slower relaxation relative to the bulk). This is due to the fact that ionic solutes at the interface are able to keep part of their solvation shell to a degree that depends on their size. Thus, a significant portion of the repulsive forces is maintained. A high degree of correlation is found between the peak height of the solvent-solute radial distribution function and the vibrational relaxation rate. The relaxation rate at the liquid/liquid interface strongly depends on the location of the solute across the interface and correlates with the change in the density and polarity profile of the interface.
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Affiliation(s)
- Ilan Benjamin
- Department of Chemistry and Biochemistry, University of California at Santa Cruz, Santa Cruz, CA 95064, USA
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Correa NM, Pires PAR, Silber JJ, El Seoud OA. Real Structure of Formamide Entrapped by AOT Nonaqueous Reverse Micelles: FT-IR and 1H NMR Studies. J Phys Chem B 2005; 109:21209-19. [PMID: 16853748 DOI: 10.1021/jp053425m] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Noninvasive techniques such as FT-IR and (1)H NMR spectroscopy have been employed to investigate the solubilization of formamide, FA, and its aqueous solution, FA-water, by sodium 1,4-bis(2-ethylhexyl)sulfosuccinate, AOT, in heptane or isooctane reverse micelles, respectively. Partially deuterated FA (FADH) was used in the FT-IR experiments and nu(OD), n(ND) were analyzed. Also, the nu(C=O) band of FA was investigated. For AOT, the changes of the SO(3)(-) group's symmetric, nu(s), and asymmetric, nu(a), bands were also studied. The results are showing that FA is interacting strongly with the Na+ counterions of the surfactant through electrostatic interactions maintaining their hydrogen bond network present in the FA bulk. Accordingly, partially deuterated FA is "frozen" inside the aggregates and it is possible to detect, by FT-IR technique, the cis and trans isomers. Curve fitting of the nu(OD) (in the FA-water mixture) band requires use of two peaks because the band is asymmetric, not because the solubilizate molecules are present in layers of different structure. The chemical shifts of the (1)H bound to N and C of FA were studied by (1)H NMR. The comparison of the chemical shift of AOT in reverse micelles with FA and the FA-water mixture in the polar core of the aggregate shows that there is a strong preferential solvation of Na+ by FA (through electrostatic interaction) and the AOT's sulfonate group by water (through hydrogen bond interaction).
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Affiliation(s)
- N Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia Postal # 3, C.P. 5800 Río Cuarto, Argentina.
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