Seeing through solvent effects using molecular balances

Mati, Ioulia K.; Adam, Catherine; Cockroft, Scott L.

doi:10.1039/c3sc51764k

Cited by 47 publications

(43 citation statements)

References 41 publications

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“…[10,13] Them olecular balances employed in the present study are based on previous designs that enabled the measurement of solvent and substituent effects on intramolecular interactions (Figure 2A). [14] Thep osition of the conformational equilibrium in these new balances enables measurement of the energy of the Hbond at the end of alinear chain of one,two,orthree Hbonds.These molecular balances were synthesized and found to exist in two conformational states on the NMR timescale at room temperature (see the Supporting Information for NMR spectra and minimized structures). Conformers were assigned using 2D NMR spectroscopy and the equilibrium constant K was determined by integration of the 19 FNMR peaks corresponding to each conformer.…”

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confidence: 99%

Strong Short‐Range Cooperativity in Hydrogen‐Bond Chains

et al. 2017

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Chains of hydrogen bonds such as those found in water and proteins are often presumed to be more stable than the sum of the individual H bonds. However, the energetics of cooperativity are complicated by solvent effects and the dynamics of intermolecular interactions, meaning that information on cooperativity typically is derived from theory or indirect structural data. Herein, we present direct measurements of energetic cooperativity in an experimental system in which the geometry and the number of H bonds in a chain were systematically controlled. Strikingly, we found that adding a second H‐bond donor to form a chain can almost double the strength of the terminal H bond, while further extensions have little effect. The experimental observations add weight to computations which have suggested that strong, but short‐range cooperative effects may occur in H‐bond chains.

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confidence: 99%

Strong Short‐Range Cooperativity in Hydrogen‐Bond Chains

et al. 2017

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“…Remarkably, the application of this new approach allowed Cockroft et al. to detect an unusual C=O⋅⋅⋅NO 2 interaction, with the estimated stabilisation energy of up to 3.6 kJ mol −1 …”

Section: Cockroft Balancesmentioning

confidence: 97%

“…To study the dependence of noncovalent interactions on solvent and substituent effects, Cockroft and co‐workers designed a series of synthetic derivatives of N , N ‐diphenylformamide and N ‐pyridyl‐ N ‐phenylformamide (Figure ) . A large number of experimentally derived Δ G° values were examined using a simple solvation model, which enabled to distinguish the role of intra‐ and intermolecular interactions.…”

Section: Cockroft Balancesmentioning

confidence: 99%

Some Recent Advances in the Design and Use of Molecular Balances for the Experimental Quantification of Intramolecular Noncovalent Interactions of π Systems

Aliev

Motherwell

2019

Chemistry A European J

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Herein, various molecular balances used for comparing the strengths of intramolecular noncovalent interactions are reviewed. Our overview indicates that considerable quantitative insight into the strength of noncovalent interactions can be gained through the careful design of molecular balances. Many exciting opportunities certainly exist for the design of further new balances to quantify and dissect the relative strengths of noncovalent interactions as a function of solvation and the importance of the many factors that contribute to overall molecular recognition. However, even simple model molecules can show a multiplicity of intramolecular noncovalent interactions acting in a combined fashion. It is therefore essential to undertake a detailed computational analysis to identify all possible noncovalent interactions present in a selected molecular balance prior to a quantitative experimental assessment of the strength of a particular noncovalent interaction. It is also argued that the words “torsion” and “molecular balance” seem to have become inextricably linked and, in consequence, even top pan and seesaw balances have been mistakenly referred to in these terms.

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“…The experimental binding data were correlated against numerous parameters that have been used to describe solvent properties including dielectric constant (r), bulk polarisability (P), surface tension (, cohesive energy density (ced) and hydrogen bond donor (a) and acceptor constants (). 2,3,4 Correlations with any of these individual properties gave correlation coefficients no better than R 2 = 0.77 even when aprotic solvents were only included in the correlations. In contrast, a correlation coefficient of R 2 = 0.93 was found for the same data when plotted against the inverse of the dielectric constant (1/r) for solvents spanning from r = 4.7…”

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confidence: 99%

“…One powerful empirical approach for dissecting the underlying physicochemical origins of molecular recognition is to perform a solvent screen, in which solvent properties such as polarisability, solvophobicity and hydrogen-bonding donor and acceptor constants are systematically varied. 3,4 However, even with neutral species it can be difficult to find suitable supramolecular model systems that enable solvent screening and the determination of reliable quantitative experimental data. The situation becomes even more difficult when charges are involved, as the solubility of the components of the system may vary wildly between different solvents, while counterion effects, conformational flexibility and preferential solvation can further complicate any attempted analysis.…”

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confidence: 99%