1
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Deshmukh SH, Yadav S, Chowdhury T, Pathania A, Sapra S, Bagchi S. Probing surface interactions in CdSe quantum dots with thiocyanate ligands. NANOSCALE 2024. [PMID: 39042097 DOI: 10.1039/d4nr01507j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Surface chemistry dictates the optoelectronic properties of semiconductor quantum dots (QDs). Tailoring these properties relies on the meticulous selection of surface ligands for efficient passivation. While long-chain organic ligands boast a well-understood passivation mechanism, the intricacies of short inorganic ionic ligands remain largely unexplored. This study sheds light on the surface-passivation mechanism of short inorganic ligands, particularly focusing on SCN- ions on CdSe QDs. Employing steady-state and time-resolved infrared spectroscopic techniques, we elucidated the surface-ligand interactions and coordination modes of SCN--capped CdSe QDs. Comparative analysis with studies on CdS QDs unveils intriguing insights into the coordination behavior and passivation efficacy of SCN- ions on Cd2+ rich QD surfaces. Our results reveal the requirement of both surface-bound (strong binding) and weakly-interacting interfacial SCN- ions for effective CdSe QD passivation. Beyond fostering a deeper understanding of surface-ligand interactions and highlighting the importance of a comprehensive exploration of ligand chemistries, this study holds implications for optimizing QD performance across diverse applications.
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Affiliation(s)
- Samadhan H Deshmukh
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune - 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad - 201002, India
| | - Sushma Yadav
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Tubai Chowdhury
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune - 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad - 201002, India
| | - Akhil Pathania
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune - 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad - 201002, India
| | - Sameer Sapra
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune - 411008, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad - 201002, India
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2
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Liang H, Xia X, Liu M, Zou S, Yin T, Li H, Zhang Y, Min C, Bu Y. Competition-Induced Macroscopic Superlubricity of Ionic Liquid Analogues by Hydroxyl Ligands Revealed by in Situ Raman. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:4277-4284. [PMID: 38360538 DOI: 10.1021/acs.langmuir.3c03461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
High load-bearing capacity is one of the crucial indicators for liquid superlubricants to move toward practicality. However, some of the current emerging systems not only have low contact pressures but also are highly susceptible to further degradation due to water adsorption and even superlubricity failure. Herein, a novel choline chloride-based ionic liquid analogues (ILAs) of a superlubricant with triethanolamine (TEOA) as the H-bond donor is reported for the first time; it obtains an ultralow coefficient of friction (0.005) and high load-bearing capacity (360 MPa, more than 2 times that of similar systems) due to adsorption of a small amount of water (<5 wt %) from the air. In situ Raman combined with 1H NMR and FTIR techniques reveals that adsorbed water competes with the hydroxyl group of TEOA for coordination with Cl-, leading to the conversion of some strong H-bonds to weak H-bonds in ILAs; the localized strong H-bonds and weak H-bonds endow the ILAs with high load-bearing capacity and the formation of ultralow shear-resistance sliding interfaces, respectively, under the shear motion. This study proposes a strategy to modulate the interactions between liquid species using adsorbed water from air as a competing ligand, which provides new insights into the design of ILA-based macroscopic liquid superlubricants with a high load-bearing capacity.
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Affiliation(s)
- Hongyu Liang
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Xiaojie Xia
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Manqiang Liu
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Shijing Zou
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Tianqiang Yin
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Hongfei Li
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Yanhu Zhang
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Chunying Min
- School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Yongfeng Bu
- Institute for Energy Research, Jiangsu University, Zhenjiang 212013, China
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3
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Chowdhury T, Chatterjee S, Deshmukh SH, Bagchi S. A Systematic Study on the Role of Hydrogen Bond Donors in Dictating the Dynamics of Choline-Based Deep Eutectic Solvents. J Phys Chem B 2023; 127:7299-7308. [PMID: 37561654 DOI: 10.1021/acs.jpcb.3c02191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Deep eutectic solvents, promising green alternatives to conventional solvents, consist of a hydrogen bond donor and a hydrogen bond acceptor. The hydrogen bonding components in deep eutectic solvents form an extended hydrogen bonding network, which can be tuned to specific applications by changing the hydrogen bond donors. In this work, we have changed the hydrogen bond donor from a diol to a dicarboxylic acid by systematically replacing a hydroxyl group with an acid group one at a time to investigate the solvation structure and dynamics of the deep eutectic systems. Using a combination of ultrafast vibrational spectroscopy and molecular dynamics simulations, we compared the spectral diffusion and orientational relaxation dynamics of three deep eutectic systems using the vibrational responses of a dissolved anion. Our results indicate that although the solvation structures are marginally different across the systems, distinct differences are present in the solvent fluctuation and solute reorientation dynamics. This work provides a detailed molecular understanding of carboxylic-acid-based deep eutectic systems and how they differ from alcohol-based deep eutectic systems.
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Affiliation(s)
- Tubai Chowdhury
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Srijan Chatterjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Samadhan H Deshmukh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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4
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Chatterjee S, Chowdhury T, Bagchi S. Does variation in composition affect dynamics when approaching the eutectic composition? J Chem Phys 2023; 158:114203. [PMID: 36948840 DOI: 10.1063/5.0139153] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Deep eutectic solvent is a mixture of two or more components, mixed in a certain molar ratio, such that the mixture melts at a temperature lower than individual substances. In this work, we have used a combination of ultrafast vibrational spectroscopy and molecular dynamics simulations to investigate the microscopic structure and dynamics of a deep eutectic solvent (1:2 choline chloride: ethylene glycol) at and around the eutectic composition. In particular, we have compared the spectral diffusion and orientational relaxation dynamics of these systems with varying compositions. Our results show that although the time-averaged solvent structures around a dissolved solute are comparable across compositions, both the solvent fluctuations and solute reorientation dynamics show distinct differences. We show that these subtle changes in solute and solvent dynamics with changing compositions arise from the variations in the fluctuations of the different intercomponent hydrogen bonds.
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Affiliation(s)
- Srijan Chatterjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Tubai Chowdhury
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
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5
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Solvation structure and dynamics of a small ion in an organic electrolyte. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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6
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Liang H, Yin T, Liu M, Fu C, Xia X, Zou S, Hua X, Fu Y, Bu Y. Unravelling High-Load Superlubricity of Ionic Liquid Analogues by In Situ Raman: Incomplete Hydration Induced by Competitive Exchange of External Water with Crystalline Water. J Phys Chem Lett 2023; 14:453-459. [PMID: 36622949 DOI: 10.1021/acs.jpclett.2c03667] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
A high load-carrying capacity is the key to the practicality of liquid superlubricity, but it is difficult to achieve high load and low friction simultaneously by relying solely on a liquid film. Herein, a choline chloride-based ionic liquid analogue (ILA) macroscale superlubricant is first reported by tuning down strong hydrogen bonding in the ILA via introducing 2-10 wt % water, with a high load of 160 MPa and a low coefficient of friction of 0.006-0.008. In situ Raman reveals that competitive exchange between external water and crystalline water induces weak H-bond-dominated incomplete hydration, conferring a low-shear interface and considerable load-carrying capacity inside the lubricant. It is a hydrodynamic lubrication film rather than a tribochemical/physical adsorption film, allowing it to be applied to friction pairs of various materials. This study unveils the principle of water mediation of high-viscosity ILAs and also provides new insights into the design of practical ILA-based superlubrication materials with high load-carrying capacity.
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Affiliation(s)
- Hongyu Liang
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Tianqiang Yin
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Manqiang Liu
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Caihong Fu
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Xiaojie Xia
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Shijing Zou
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Xijun Hua
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Yonghong Fu
- Institute of Advanced Manufacturing and Modern Equipment Technology, School of Mechanical Engineering, Jiangsu University, Zhenjiang212013, China
| | - Yongfeng Bu
- Institute for Energy Research, Jiangsu University, Zhenjiang212013, China
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7
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Sanchez-Fernandez A, Basic M, Xiang J, Prevost S, Jackson AJ, Dicko C. Hydration in Deep Eutectic Solvents Induces Non-monotonic Changes in the Conformation and Stability of Proteins. J Am Chem Soc 2022; 144:23657-23667. [PMID: 36524921 PMCID: PMC9801427 DOI: 10.1021/jacs.2c11190] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The preservation of labile biomolecules presents a major challenge in chemistry, and deep eutectic solvents (DESs) have emerged as suitable environments for this purpose. However, how the hydration of DESs impacts the behavior of proteins is often neglected. Here, we demonstrate that the amino acid environment and secondary structure of two proteins (bovine serum albumin and lysozyme) and an antibody (immunoglobulin G) in 1:2 choline chloride:glycerol and 1:2 choline chloride:urea follow a re-entrant behavior with solvent hydration. A dome-shaped transition is observed with a folded or partially folded structure at very low (<10 wt % H2O) and high (>40 wt % H2O) DES hydration, while protein unfolding increases between those regimes. Hydration also affects protein conformation and stability, as demonstrated for bovine serum albumin in hydrated 1:2 choline chloride:glycerol. In the neat DES, bovine serum albumin remains partially folded and unexpectedly undergoes unfolding and oligomerization at low water content. At intermediate hydration, the protein begins to refold and gradually retrieves the native monomer-dimer equilibrium. However, ca. 36 wt % H2O is required to recover the native folding fully. The half-denaturation temperature of the protein increases with decreasing hydration, but even the dilute DESs significantly enhance the thermal stability of bovine serum albumin. Also, protein unfolding can be reversed by rehydrating the sample to the high hydration regime, also recovering protein function. This correlation provides a new perspective to understanding protein behavior in hydrated DESs, where quantifying the DES hydration becomes imperative to identifying the folding and stability of proteins.
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Affiliation(s)
- Adrian Sanchez-Fernandez
- Centro
Singular de Investigación en Química Biolóxica
e Materiais Moleculares (CIQUS), Universidade
de Santiago de Compostela, Rúa de Jenaro de la Fuente, s/n, Santiago de Compostela 15705, Spain,Food
Technology, Engineering and Nutrition, Lund
University, Box 124, Lund 221 00, Sweden,
| | - Medina Basic
- Food
Technology, Engineering and Nutrition, Lund
University, Box 124, Lund 221 00, Sweden
| | - Jenny Xiang
- Food
Technology, Engineering and Nutrition, Lund
University, Box 124, Lund 221 00, Sweden
| | - Sylvain Prevost
- Institut
Laue-Langevin, DS / LSS,
71 Avenue des Martyrs, Grenoble 38000, France
| | - Andrew J. Jackson
- European
Spallation Source, Box
176, Lund 221 00, Sweden,Department
of Physical Chemistry, Lund University, Box 124, Lund 221 00, Sweden
| | - Cedric Dicko
- Pure
and
Applied Biochemistry, Department of Chemistry, Lund University, Box
124, Lund SE-221 00, Sweden,Lund
Institute of Advanced Neutron and X-ray Science, SE-223 70 Lund, Sweden
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8
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GO/ionic surfactant inspired photophysical modulation of rhodamine B in Reline with or without additives. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120614] [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]
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9
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Chatterjee S, Deshmukh SH, Bagchi S. Does Viscosity Drive the Dynamics in an Alcohol-Based Deep Eutectic Solvent? J Phys Chem B 2022; 126:8331-8337. [PMID: 36200737 DOI: 10.1021/acs.jpcb.2c06521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Deep eutectic solvents, consisting of heterogeneous nanodomains of hydrogen-bonded networks, have evolved into a range of viscous fluids that find applications in several fields. As viscosity is known to influence the dynamics of other neoteric solvents like ionic liquids, understanding the effect of viscosity on deep eutectic solvents is crucial to realize their full potential. Herein, we combine polarization-selective pump-probe spectroscopy, two-dimensional infrared spectroscopy, and molecular dynamics simulations to elucidate the impact of viscosity on the dynamics of an alcohol-based deep eutectic solvent, ethaline. We compare the solvent fluctuation and solute reorientation time scales in ethaline with those in ethylene glycol, an ethaline constituent. Interestingly, we find that the solute's reorientation apparently scales the bulk viscosity of the solvent, but the same is not valid for the overall solvation dynamics. Using the variations in the estimated intercomponent hydrogen bond lifetimes, we show that a dissolved solute does not sense the bulk viscosity of the deep eutectic solvent; instead, it senses domain-specific local viscosity determined by the making and breaking of the hydrogen bond network. Our results indicate that understanding the domain-specific local environment experienced by the dissolved solute is of utmost importance in deep eutectic solvents.
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Affiliation(s)
- Srijan Chatterjee
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
| | - Samadhan H Deshmukh
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha Road, Pune411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad201002, India
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10
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Töpfer K, Pasti A, Das A, Salehi SM, Vazquez-Salazar LI, Rohrbach D, Feurer T, Hamm P, Meuwly M. Structure, Organization, and Heterogeneity of Water-Containing Deep Eutectic Solvents. J Am Chem Soc 2022; 144:14170-14180. [PMID: 35895323 DOI: 10.1021/jacs.2c04169] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The spectroscopy and structural dynamics of a deep eutectic mixture (KSCN/acetamide) with varying water content is investigated from 2D IR (with the C-N stretch vibration of the SCN- anions as the reporter) and THz spectroscopy. Molecular dynamics simulations correctly describe the nontrivial dependence of both spectroscopic signatures depending on water content. For the 2D IR spectra, the MD simulations relate the steep increase in the cross-relaxation rate at high water content to the parallel alignment of packed SCN- anions. Conversely, the nonlinear increase of the THz absorption with increasing water content is mainly attributed to the formation of larger water clusters. The results demonstrate that a combination of structure-sensitive spectroscopies and molecular dynamics simulations provides molecular-level insights into the emergence of heterogeneity of such mixtures by modulating their composition.
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Affiliation(s)
- Kai Töpfer
- Department of Chemistry, University of Basel, CH-4056 Basel, Switzerland
| | - Andrea Pasti
- Department of Chemistry, University of Zurich, CH-8057 Zürich, Switzerland
| | - Anuradha Das
- Institute of Applied Physics, University of Bern, CH-3012 Bern, Switzerland
| | | | | | - David Rohrbach
- Institute of Applied Physics, University of Bern, CH-3012 Bern, Switzerland
| | - Thomas Feurer
- Institute of Applied Physics, University of Bern, CH-3012 Bern, Switzerland
| | - Peter Hamm
- Department of Chemistry, University of Zurich, CH-8057 Zürich, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, CH-4056 Basel, Switzerland
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11
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Kumari M, Kumari P, Kashyap HK. Structural adaptations in the bovine serum albumin protein in archetypal deep eutectic solvent reline and its aqueous mixtures. Phys Chem Chem Phys 2022; 24:5627-5637. [PMID: 35175257 DOI: 10.1039/d1cp05829k] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The global concern over the environmental impact and challenges associated with the use of conventional solvents in biotransformation processes have pushed the search for alternative solvents. Recently, deep eutectic solvents (DESs) have appeared as a promising replacement with better biocompatibility and have been postulated to hold great potential in protein engineering and crystallization processes. In this context, herein, we have investigated the effect of reline (a choline chloride : urea mixture in 1 : 2 proportion) DES in its pure and hydrated forms on the structural stability and conformation of the bovine serum albumin (BSA) protein using all-atom molecular dynamics simulations. We observe a substantial overall expansion of the BSA structure with a simultaneous increment in the solvent accessible surface area, signifying the influence of reline on the BSA tertiary structure. These induced structural perturbations are quite pronounced in reline-water mixtures. Concomitantly, a notable reline concentration-dependent disruption of the BSA secondary structure through the melting of α-helices, mainly driven by H-bonding interactions, is observed. In the presence of pure reline, significant rigidity in the protein backbone is also observed. Thus, despite the expansion, the BSA tertiary structure in pure reline is found to be most close to the native protein structure and remains in a partially folded state at all the studied reline concentrations. In pure reline, BSA-urea hydrogen bonding is more prevalent than BSA-[Ch]+. We also observe that in aqueous reline systems, the BSA-water hydrogen bonds are mostly compensated by BSA-urea hydrogen bonds. The aqueous re-equilibration of these partially denatured protein conformations showed a significant recovery of secondary and tertiary structures, where the recovery is most profound for the BSA conformation extracted from pure reline.
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Affiliation(s)
- Monika Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Pratibha Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Hemant K Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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12
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Ghosh D, Sakpal SS, Chatterjee S, Deshmukh SH, Kwon H, Kim YS, Bagchi S. Association-Dissociation Dynamics of Ionic Electrolytes in Low Dielectric Medium. J Phys Chem B 2021; 126:239-248. [PMID: 34961310 DOI: 10.1021/acs.jpcb.1c08613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ionic electrolytes are known to form various complexes which exist in dynamic equilibrium in a low dielectric medium. However, structural characterization of these complexes has always posed a great challenge to the scientific community. An additional challenge is the estimation of the dynamic association-dissociation time scales (lifetime of the complexes), which are key to the fundamental understanding of ion transport. In this work, we have used a combination of infrared absorption spectroscopy, two-dimensional infrared spectroscopy, molecular dynamics simulations, and density functional theory calculations to characterize the various ion complexes formed by the thiocyanate-based ionic electrolytes as a function of different cations in a low dielectric medium. Our results demonstrate that thiocyanate is an excellent vibrational reporter of the heterogeneous ion complexes undergoing association-dissociation dynamics. We find that the ionic electrolytes exist as contact ion pairs, dimers, and clusters in a low dielectric medium. The relative ratios of the various ion complexes are sensitive to the cations. In addition to the interactions between the thiocyanate anion and the countercation, the solute-solvent interactions drive the dynamic equilibrium. We have estimated the association-dissociation dynamics time scales from two-dimensional infrared spectroscopy. The exchange time scale involving the cluster is faster than that between a dimer and an ion pair. Moreover, we find that the dynamic equilibrium between the cluster and another ion complex is correlated to the solvent fluctuations.
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Affiliation(s)
- Deborin Ghosh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India
| | - Sushil S Sakpal
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Srijan Chatterjee
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Samadhan H Deshmukh
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Hyejin Kwon
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Korea
| | - Yung Sam Kim
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan 44919, Korea
| | - Sayan Bagchi
- Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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13
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Sarkar S, Maity A, Chakrabarti R. In Silico Elucidation of Molecular Picture of Water-Choline Chloride Mixture. J Phys Chem B 2021; 125:13212-13228. [PMID: 34812630 DOI: 10.1021/acs.jpcb.1c06636] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Choline chloride (ChCl) is a component of several deep eutectic solvents (DESs) having numerous applications. Recent studies have reported manifold promising use of aqueous choline chloride solution as an alternative to DES, where water plays the role of the hydrogen-bond donor. The characteristic physical properties of the DESs and aqueous DES originate from the "inter-" and intraspecies hydrogen-bond network formed by the constituents. However, a detailed molecular-level picture of choline chloride and water mixture is largely lacking in the literature. This motivates us to carry out extensive all-atom molecular dynamics simulations of the ChCl-water mixture of varying compositions. Our analyses clearly show an overall increase in the interspecies association with an increase in ChCl concentration. At higher concentrations, the trimethylammonium groups of choline are stabilized by a nonpolar interaction, whereas the hydroxyl groups preferentially interact with water. Chloride ions are found to be involved in two types of interactions: one where chloride ions intercalate two or more choline cations, and the other one where they are surrounded by five to six water molecules forming solvated chloride ions. However, the relative fractions of these two types of associations depend on the concentration of ChCl in the mixture. Another important structural aspect is the disruption of the hydrogen-bonded water network due to the presence of both choline cations and chloride ions. However, chloride ions participate to partially restore the tetrahedral arrangement of partners around water molecules.
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Affiliation(s)
- Soham Sarkar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Atanu Maity
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
| | - Rajarshi Chakrabarti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India
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