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Iddon B, Hunter CA. Solvation-Enhanced Salt Bridges. J Am Chem Soc 2024. [PMID: 39364787 DOI: 10.1021/jacs.4c11869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2024]
Abstract
Salt bridges formed by amidines and carboxylic acids represent an important class of noncovalent interaction in biomolecular and supramolecular systems. Isothermal titration calorimetry was used to study the relationships between the strength of the interaction, the chemical structures of the components, and the nature of the solvent. The stability of the 1:1 complex formed in chloroform changed by 2 orders of magnitude depending on the basicity of the amidine and the acidity of the acid, which is consistent with proton transfer in the complex. Polar solvents reduce the stabilities of salt bridges formed with N,N'-dialkylamidines by up to 3 orders of magnitude, but this dependence on solvent polarity can be eliminated if the alkyl groups are replaced by protons in the parent amidine. The enhanced stability of the complex formed by benzamidine is due to solvation of the NH sites not directly involved in salt bridge formation, which become significantly more polar when proton transfer takes place, leading to more favorable interactions with polar solvents in the bound state. Calculation of H-bond parameters using density functional theory was used to predict solvent effects on the stabilities of salt bridges to within 1 kJ mol-1. While H-bonding interactions are strong in nonpolar solvents, and solvophobic interactions are strong in polar protic solvents, these interactions are weak in polar aprotic solvents. In contrast, amidinium-carboxylate salt bridges are stable in both polar and nonpolar aprotic solvents, which is attractive for the design of supramolecular systems that operate in different solvent environments.
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Affiliation(s)
- Ben Iddon
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
| | - Christopher A Hunter
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K
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Manna D, Lo R, Vacek J, Miriyala VM, Bouř P, Wu T, Osifová Z, Nachtigallová D, Dračinský M, Hobza P. The Stability of Hydrogen-Bonded Ion-Pair Complex Unexpectedly Increases with Increasing Solvent Polarity. Angew Chem Int Ed Engl 2024; 63:e202403218. [PMID: 38497312 DOI: 10.1002/anie.202403218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/12/2024] [Accepted: 03/13/2024] [Indexed: 03/19/2024]
Abstract
The generally observed decrease of the electrostatic energy in the complex with increasing solvent polarity has led to the assumption that the stability of the complexes with ion-pair hydrogen bonds decreases with increasing solvent polarity. Besides, the smaller solvent-accessible surface area (SASA) of the complex in comparison with the isolated subsystems results in a smaller solvation energy of the latter, leading to a destabilization of the complex in the solvent compared to the gas phase. In our study, which combines Nuclear Magnetic Resonance, Infrared Spectroscopy experiments, quantum chemical calculations, and molecular dynamics (MD) simulations, we question the general validity of this statement. We demonstrate that the binding free energy of the ion-pair hydrogen-bonded complex between 2-fluoropropionic acid and n-butylamine (CH3CHFCOO-…NH3But+) increases with increased solvent polarity. This phenomenon is rationalized by a substantial charge transfer between the subsystems that constitute the ion-pair hydrogen-bonded complex. This unexpected finding introduces a new perspective to our understanding of solvation dynamics, emphasizing the interplay between solvent polarity and molecular stability within hydrogen-bonded systems.
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Affiliation(s)
- Debashree Manna
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Rabindranath Lo
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Jaroslav Vacek
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
- IT4Innovations, VŠB-Technical University of Ostrava, 17. Listopadu 2172/15, 708 00, Ostrava-Poruba, Czech Republic
- Faculty of Science, Palacký University Olomouc, 17. Listopadu 1192/12, 779 00, Olomouc, Czech Republic
| | - Vijay Madhav Miriyala
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Petr Bouř
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Tao Wu
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Zuzana Osifová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Dana Nachtigallová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
- IT4Innovations, VŠB-Technical University of Ostrava, 17. Listopadu 2172/15, 708 00, Ostrava-Poruba, Czech Republic
| | - Martin Dračinský
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
| | - Pavel Hobza
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo námĕstí 542/2, 160 00, Prague, Czech Republic
- IT4Innovations, VŠB-Technical University of Ostrava, 17. Listopadu 2172/15, 708 00, Ostrava-Poruba, Czech Republic
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Manna D, Lo R, Miriyala VM, Nachtigallová D, Trávníček Z, Hobza P. Impact of dielectric constant of solvent on the formation of transition metal-ammine complexes. J Comput Chem 2024; 45:204-209. [PMID: 37752737 DOI: 10.1002/jcc.27230] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 08/29/2023] [Accepted: 09/04/2023] [Indexed: 09/28/2023]
Abstract
The DFT-level computational investigations into Gibbs free energies (ΔG) demonstrate that as the dielectric constant of the solvent increases, the stabilities of [M(NH3 )n ]2+/3+ (n = 4, 6; M = selected 3d transition metals) complexes decrease. However, there is no observed correlation between the stability of the complex and the solvent donor number. Analysis of the charge transfer and Wiberg bond indices indicates a dative-bond character in all the complexes. The solvent effect assessed through solvation energy is determined by the change in the solvent accessible surface area (SASA) and the change in the charge distribution that occurs during complex formation. It has been observed that the SASA and charge transfer are different in the different coordination numbers, resulting in a variation in the solvent effect on complex stability in different solvents. This ultimately leads to a change between the relative stability of complexes with different coordination numbers while increasing the solvent polarity for a few complexes. Moreover, the findings indicate a direct relationship between ΔΔG (∆Gsolvent -∆Ggas ) and ΔEsolv , which enables the computation of ΔG for the compounds in a particular solvent using only ΔGgas and ΔEsolv . This approach is less computationally expensive.
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Affiliation(s)
- Debashree Manna
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
| | - Rabindranath Lo
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University, Olomouc, Czech Republic
| | - Vijay Madhav Miriyala
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University, Olomouc, Czech Republic
| | - Dana Nachtigallová
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
- IT4Innovations, VŠB-Technical University of Ostrava, Ostrava, Czech Republic
| | - Zdeněk Trávníček
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University, Olomouc, Czech Republic
| | - Pavel Hobza
- Czech Academy of Sciences, Institute of Organic Chemistry and Biochemistry, Prague, Czech Republic
- IT4Innovations, VŠB-Technical University of Ostrava, Ostrava, Czech Republic
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Lo R, Manna D, Miriyala VM, Nachtigallová D, Hobza P. Trends in the stability of covalent dative bonds with variable solvent polarity depend on the charge transfer in the Lewis electron-pair system. Phys Chem Chem Phys 2023; 25:25961-25964. [PMID: 37727041 DOI: 10.1039/d3cp03445c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/21/2023]
Abstract
In general, the stability of neutral complexes with dative bonds increases as the polarity of the solvent increases. This is based on the fact that the dipole moment of the complex increases as the charge transferred from the donor to the acceptor increases. As a result, the solvation energy of the complex becomes greater than that of subsystems, causing an increase in the stabilization energy with increasing solvent polarity. Our research confirms this assumption, but only when the charge transfer is sufficiently large. If it is below a certain threshold, the increase in the complex's dipole moment is insufficient to result in a higher solvation energy than subsystems. Thus, the magnitude of the charge transfer in the Lewis electron-pair system determines the stability trends of dative bonds with varying solvent polarity. We used molecular dynamics (MD) simulations based on an explicit solvent model, which is considered more reliable, to verify the results obtained with a continuous solvent model.
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Affiliation(s)
- Rabindranath Lo
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, Prague 6 16000, Czech Republic.
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University Olomouc, Křížkovského 511/8, Olomouc 77900, Czech Republic
| | - Debashree Manna
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, Prague 6 16000, Czech Republic.
| | - Vijay Madhav Miriyala
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, Prague 6 16000, Czech Republic.
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute, Palacký University Olomouc, Křížkovského 511/8, Olomouc 77900, Czech Republic
| | - Dana Nachtigallová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, Prague 6 16000, Czech Republic.
- IT4Innovations, VŠB-Technical University of Ostrava, 17. listopadu 2172/15, Ostrava-Poruba 70800, Czech Republic
| | - Pavel Hobza
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, v.v.i., Flemingovo nám. 2, Prague 6 16000, Czech Republic.
- IT4Innovations, VŠB-Technical University of Ostrava, 17. listopadu 2172/15, Ostrava-Poruba 70800, Czech Republic
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Seijas LE, Zambrano CH, Almeida R, Alí-Torres J, Rincón L, Torres FJ. Exploring the Non-Covalent Bonding in Water Clusters. Int J Mol Sci 2023; 24:ijms24065271. [PMID: 36982342 PMCID: PMC10049637 DOI: 10.3390/ijms24065271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/13/2023] [Accepted: 02/16/2023] [Indexed: 03/12/2023] Open
Abstract
QTAIM and source function analysis were used to explore the non-covalent bonding in twelve different water clusters (H2O)n obtained by considering n = 2–7 and various geometrical arrangements. A total of seventy-seven O−H⋯O hydrogen bonds (HBs) were identified in the systems under consideration, and the examination of the electron density at the bond critical point (BCP) of these HBs revealed the existence of a great diversity of O−H⋯O interactions. Furthermore, the analysis of quantities, such as |V(r)|/G(r) and H(r), allowed a further description of the nature of analogous O−H⋯O interactions within each cluster. In the case of 2-D cyclic clusters, the HBs are nearly equivalent between them. However, significant differences among the O−H⋯O interactions were observed in 3-D clusters. The assessment of the source function (SF) confirmed these findings. Finally, the ability of SF to decompose the electron density (ρ) into atomic contributions allowed the evaluation of the localized or delocalized character of these contributions to ρ at the BCP associated to the different HBs, revealing that weak O−H⋯O interactions have a significant spread of the atomic contributions, whereas strong interactions have more localized atomic contributions. These observations suggest that the nature of the O−H⋯O hydrogen bond in water clusters is determined by the inductive effects originated by the different spatial arrangements of the water molecules in the studied clusters.
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Affiliation(s)
- Luis E. Seijas
- Grupo de Química Computacional y Teórica (QCT-UR), Escuela de Ingeniería Ciencia y Tecnología (EICT), Universidad del Rosario, Bogotá 111221, Colombia
| | - Cesar H. Zambrano
- Grupo de Química Computacional y Teórica (QCT-USFQ), Departamento de Ingeniería Química, Universidad San Francisco de Quito, Diego de Robles y Vía Interoceánica, Quito 17-1200-841, Ecuador
| | - Rafael Almeida
- Laboratorio de Procesos Dinámicos en Química, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela
| | - Jorge Alí-Torres
- Departamento de Química, Universidad Nacional de Colombia, Av. Cra. 30 #45-03, Bogotá 111321, Colombia
| | - Luis Rincón
- Grupo de Química Computacional y Teórica (QCT-USFQ), Departamento de Ingeniería Química, Universidad San Francisco de Quito, Diego de Robles y Vía Interoceánica, Quito 17-1200-841, Ecuador
| | - Fernando Javier Torres
- Grupo de Química Computacional y Teórica (QCT-UR), Escuela de Ingeniería Ciencia y Tecnología (EICT), Universidad del Rosario, Bogotá 111221, Colombia
- Grupo de Química Computacional y Teórica (QCT-USFQ), Departamento de Ingeniería Química, Universidad San Francisco de Quito, Diego de Robles y Vía Interoceánica, Quito 17-1200-841, Ecuador
- Correspondence:
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