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Sam S, Sung S, Krem S, Park S, Hwang DS, Kim D. Sum-Frequency Vibrational Spectroscopic Study of the Cation-π Interaction: Amine and Guanidine. J Phys Chem B 2022; 126:7621-7626. [PMID: 36166344 DOI: 10.1021/acs.jpcb.2c05709] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cation-π interaction is an interaction between a positively charged cation and π electrons in an aromatic group of a molecule. It is considered to play key roles in signal transduction, stabilization of the protein structure, enzyme catalysis in biology, and wet adhesion and biomolecular condensation. In this study, octadecylguanidine hydrochloride (ODG) and octadecylamine (ODA) having guanidine and amine headgroups, respectively, are found to interact with π molecules (phenol or indole) as investigated by sum-frequency vibrational spectroscopy. ODG is unstable and does not form a neat monolayer on the water surface. However, after adding π molecules into subphase water, it becomes more stable against dissolution as evidenced by the appearance of its CHx peaks and a CH peak of the aromatic ring in the sum-frequency spectrum. Unlike ODG, ODA forms a stable monolayer on the water surface at a neutral pH. After adding π molecules into the solution, the amine-π interaction promotes the protonation of the amine headgroup and the penetration of the π molecules makes the ODA monolayer more disordered. Indole is found to be more effective in binding with the ODG as compared to phenol.
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Affiliation(s)
- Sokhuoy Sam
- Department of Physics, Sogang University, 35, Baekbeom-ro, Mapo-gu, Seoul 04107, Korea
| | - Siheon Sung
- Department of Physics, Sogang University, 35, Baekbeom-ro, Mapo-gu, Seoul 04107, Korea
| | - Sona Krem
- Department of Physics, Sogang University, 35, Baekbeom-ro, Mapo-gu, Seoul 04107, Korea
| | - Sohee Park
- Division of Environmental Science and Engineering (DESE), Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Namgu, Pohang 37673, Korea
| | - Dong Soo Hwang
- Division of Environmental Science and Engineering (DESE), Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Namgu, Pohang 37673, Korea
| | - Doseok Kim
- Department of Physics, Sogang University, 35, Baekbeom-ro, Mapo-gu, Seoul 04107, Korea
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Judd KD, Gonzalez NM, Yang T, Cremer PS. Contact Ion Pair Formation Is Not Necessarily Stronger than Solvent Shared Ion Pairing. J Phys Chem Lett 2022; 13:923-930. [PMID: 35050629 DOI: 10.1021/acs.jpclett.1c03576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Vibrational sum frequency spectroscopy (VSFS) and pressure-area Langmuir trough measurements were used to investigate the binding of alkali metal cations to eicosyl sulfate (ESO4) surfactants in monolayers at the air/water interface. The number density of sulfate groups could be tuned by mixing the anionic surfactant with eicosanol. The equilibrium dissociation constant for K+ to the fatty sulfate interface showed 10 times greater affinity than for Li+ and approximately 3 times greater than for Na+. All three cations formed solvent shared ion pairs when the mole fraction of ESO4 was 0.33 or lower. Above this threshold charge density, Li+ formed contact ion pairs with the sulfate headgroups, presumably via bridging structures. By contrast, K+ only bound to the sulfate moieties in solvent shared ion pairing configurations. The behavior for Na+ was intermediate. These results demonstrate that there is not necessarily a correlation between contact ion pair formation and stronger binding affinity.
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Affiliation(s)
- Kenneth D Judd
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Nicole M Gonzalez
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Tinglu Yang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Paul S Cremer
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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Singh PC, Ahmed M, Nihonyanagi S, Yamaguchi S, Tahara T. DNA-Induced Reorganization of Water at Model Membrane Interfaces Investigated by Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy. J Phys Chem B 2022; 126:840-846. [DOI: 10.1021/acs.jpcb.1c08581] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Prashant Chandra Singh
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- School of Chemical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India
| | - Mohammed Ahmed
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Satoshi Nihonyanagi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Shoichi Yamaguchi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Krem S, Lee M, Sam S, Sung W, Kim D. Structure of Electric Double Layer under Cationic Langmuir Monolayer: Charge Condensation Effect. J Phys Chem Lett 2021; 12:3417-3423. [PMID: 33789054 DOI: 10.1021/acs.jpclett.1c00401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Langmuir monolayers consisting of mixtures of 1-hexadecanol (HD) and 1,2-dipalmitoyl-3-trimethylammonium-propane (DPTAP) (having quaternary amine headgroup) at different molar ratios were prepared to investigate the effect of the surface charge density on the structure of an electric double layer. The fatty alcohol molecules worked as passive spacers to widen the distance between the amine groups in the monolayer, to vary the surface charge density of the monolayer, and these mixture monolayer systems were probed by surface-sensitive sum-frequency vibrational spectroscopy. A strong sum-frequency signal in the OH range for a pure DPTAP monolayer (with a surface charge density of ∼0.4 C/m2) hardly decreased as the surface charge density was reduced up to ∼0.12 C/m2 (1 e per 140 Å2) and afterward decreased monotonically as more HD occupied the monolayer. The Gouy-Chapman theory incorporating a charged-condensed layer in which the counterion concentration is limited by a close packing of the counterions could account for the above saturation behavior in the sum-frequency spectra.
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Affiliation(s)
- Sona Krem
- Department of Physics, Sogang University, Seoul, Korea
| | - Minho Lee
- Department of Physics, Sogang University, Seoul, Korea
| | - Sokhuoy Sam
- Department of Physics, Sogang University, Seoul, Korea
| | - Woongmo Sung
- Department of Physics, Sogang University, Seoul, Korea
| | - Doseok Kim
- Department of Physics, Sogang University, Seoul, Korea
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5
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Valentine ML, Waterland MK, Fathizadeh A, Elber R, Baiz CR. Interfacial Dynamics in Lipid Membranes: The Effects of Headgroup Structures. J Phys Chem B 2021; 125:1343-1350. [DOI: 10.1021/acs.jpcb.0c08755] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Mason L. Valentine
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712-1224, United States
| | - Maya K. Waterland
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712-1224, United States
| | - Arman Fathizadeh
- Oden Institute for Computational Science and Engineering, Austin, Texas 78712, United States
| | - Ron Elber
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712-1224, United States
- Oden Institute for Computational Science and Engineering, Austin, Texas 78712, United States
| | - Carlos R. Baiz
- Department of Chemistry, University of Texas at Austin, Austin, Texas 78712-1224, United States
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Ahmed M, Nihonyanagi S, Kundu A, Yamaguchi S, Tahara T. Resolving the Controversy over Dipole versus Quadrupole Mechanism of Bend Vibration of Water in Vibrational Sum Frequency Generation Spectra. J Phys Chem Lett 2020; 11:9123-9130. [PMID: 33147973 DOI: 10.1021/acs.jpclett.0c02644] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Recently, there has been controversy over whether the HOH bend signal of water in the vibrational sum frequency generation (VSFG) spectrum arises from the conventional dipole mechanism or the quadrupole mechanism. Here, we show that the Im χ(2) (the imaginary part of the second-order nonlinear susceptibility) spectra of the HOH bend mode of water at oppositely charged monolayer/water interfaces all exhibit positive bands, irrespective of the difference in the sign of the charge at the interface. Furthermore, it is found that the peak frequency of the HOH bend band substantially changes depending on the chemical structure of the charged headgroup located at the interface. These results demonstrate that the VSFG signal of the HOH bend vibration is generated from interfacial water with the interfacial quadrupole mechanism that is associated with the large field gradient of incident lights localized in a very thin region at the interface.
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Affiliation(s)
- Mohammed Ahmed
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Satoshi Nihonyanagi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Achintya Kundu
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Shoichi Yamaguchi
- Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura, Saitama 338-8570, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Abstract
Lipid membranes are more than just barriers between cell compartments; they provide molecular environments with a finely tuned balance between hydrophilic and hydrophobic interactions that enable proteins to dynamically fold and self-assemble to regulate biological function. Characterizing dynamics at the lipid-water interface is essential to understanding molecular complexities from the thermodynamics of liquid-liquid phase separation down to picosecond-scale reorganization of interfacial hydrogen-bond networks.Ultrafast vibrational spectroscopy, including two-dimensional infrared (2D IR) and vibrational sum-frequency generation (VSFG) spectroscopies, is a powerful tool to examine picosecond interfacial dynamics. Two-dimensional IR spectroscopy provides a bond-centered view of dynamics with subpicosecond time resolutions, as vibrational frequencies are highly sensitive to the local environment. Recently, 2D IR spectroscopy has been applied to carbonyl and phosphate vibrations intrinsically located at the lipid-water interface. Interface-specific VSFG spectroscopy probes the water vibrational modes directly, accessing H-bond strength and water organization at lipid headgroup positions. Signals in VSFG arise from the interfacial dipole contributions, directly probing headgroup ordering and water orientation to provide a structural view of the interface.In this Account we discuss novel applications of ultrafast spectroscopy to lipid membranes, a field that has experienced significant growth over the past decade. In particular, ultrafast experiments now offer a molecular perspective on increasingly complex membranes. The powerful combination of ultrafast, interface-selective spectroscopy and simulations opens up new routes to understanding multicomponent membranes and their function. This Account highlights key prevailing views that have emerged from recent experiments: (1) Water dynamics at the lipid-water interface are slow compared to those of bulk water as a result of disrupted H-bond networks near the headgroups. (2) Peptides, ions, osmolytes, and cosolvents perturb interfacial dynamics, indicating that dynamics at the interface are affected by bulk solvent dynamics and vice versa. (3) The interfacial environment is generally dictated by the headgroup structure and orientation, but hydrophobic interactions within the acyl chains also modulate interfacial dynamics. Ultrafast spectroscopy has been essential to characterizing the biophysical chemistry of the lipid-water interface; however, challenges remain in interpreting congested spectra as well as designing appropriate model systems to capture the complexity of a membrane environment.
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Affiliation(s)
- Jennifer C. Flanagan
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street Stop A5300, Austin, Texas 78712-1224, United States
| | - Mason L. Valentine
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street Stop A5300, Austin, Texas 78712-1224, United States
| | - Carlos R. Baiz
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street Stop A5300, Austin, Texas 78712-1224, United States
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Ahmed M, Inoue K, Nihonyanagi S, Tahara T. Hidden Isolated OH at the Charged Hydrophobic Interface Revealed by Two‐Dimensional Heterodyne‐Detected VSFG Spectroscopy. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202002368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Mohammed Ahmed
- Molecular Spectroscopy LaboratoryRIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
- Ultrafast Spectroscopy Research TeamRIKEN Center for Advanced Photonics (RAP), RIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
| | - Ken‐ichi Inoue
- Molecular Spectroscopy LaboratoryRIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
- Present address: Department of ChemistryGraduate School of ScienceTohoku University Sendai 980-8578 Japan
| | - Satoshi Nihonyanagi
- Molecular Spectroscopy LaboratoryRIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
- Ultrafast Spectroscopy Research TeamRIKEN Center for Advanced Photonics (RAP), RIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
| | - Tahei Tahara
- Molecular Spectroscopy LaboratoryRIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
- Ultrafast Spectroscopy Research TeamRIKEN Center for Advanced Photonics (RAP), RIKEN 2-1 Hirosawa Wako Saitama 351-0198 Japan
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9
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Ahmed M, Inoue KI, Nihonyanagi S, Tahara T. Hidden Isolated OH at the Charged Hydrophobic Interface Revealed by Two-Dimensional Heterodyne-Detected VSFG Spectroscopy. Angew Chem Int Ed Engl 2020; 59:9498-9505. [PMID: 32189396 DOI: 10.1002/anie.202002368] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Indexed: 02/04/2023]
Abstract
Water around hydrophobic groups mediates hydrophobic interactions that play key roles in many chemical and biological processes. Thus, the molecular-level elucidation of the properties of water in the vicinity of hydrophobic groups is important. We report on the structure and dynamics of water at two oppositely charged hydrophobic ion/water interfaces, that is, the tetraphenylborate-ion (TPB- )/water and tetraphenylarsonium-ion (TPA+ )/water interfaces, which are clarified by two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy. The obtained 2D HD-VSFG spectra of the anionic TPB- interface reveal the existence of distinct π-hydrogen bonded OH groups in addition to the usual hydrogen-bonded OH groups, which are hidden in the steady-state spectrum. In contrast, 2D HD-VSFG spectra of the cationic TPA+ interface only show the presence of usual hydrogen-bonded OH groups. The present study demonstrates that the sign of the interfacial charge governs the structure and dynamics of water molecules that face the hydrophobic region.
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Affiliation(s)
- Mohammed Ahmed
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Ken-Ichi Inoue
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.,Present address: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan
| | - Satoshi Nihonyanagi
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Tahei Tahara
- Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.,Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics (RAP), RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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Baksi A, Ghorai PK, Biswas R. Dynamic Susceptibility and Structural Heterogeneity of Large Reverse Micellar Water: An Examination of the Core–Shell Model via Probing the Layer-wise Features. J Phys Chem B 2020; 124:2848-2863. [DOI: 10.1021/acs.jpcb.9b11895] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Atanu Baksi
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake, Kolkata 700106, India
| | - Pradip Kr. Ghorai
- Indian Institute of Science Education and Research, Mohanpur, Nadia, Kolkata 741246, India
| | - Ranjit Biswas
- Department of Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake, Kolkata 700106, India
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Benderskii A, Morita A. Nonlinear spectroscopy and interfacial structure and dynamics. J Chem Phys 2019; 151:150401. [PMID: 31640380 DOI: 10.1063/1.5129103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alexander Benderskii
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Akihiro Morita
- Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan
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12
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Ultrafast Vibrational Dynamics at Aqueous Interfaces Studied by 2D Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy. SPRINGER SERIES IN OPTICAL SCIENCES 2019. [DOI: 10.1007/978-981-13-9753-0_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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