Role of hydroxyl concentrations in solvatochromic measures of solvent polarity of alcohols and alcohol–water mixtures—evidence that preferential solvation effects may be overestimated

Bentley, T. William; Koo, In Sun

doi:10.1039/b408052c

Cited by 28 publications

(82 citation statements)

References 48 publications

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“…The degree of aggregation is shown in Figure and is graphed as a function of the polarity index of the solutions. This parameter is linear for methanol:water binary solvents . The polarity index is 10.2 for water and 5.1 for methanol .…”

Section: Resultsmentioning

confidence: 97%

“…This parameter is linear for methanol:water binarys olvents. [53] The polarity index is 10.2 for water and 5.1 for methanol. [54] Therefore, the polarity index values of the solutionsw ere determined using the relationship PI = c MeOH PI(MeOH) + c H 2 O PI(H 2 O), where PI is the polarity index and c is the volumef raction of the methanol and water used in this work.…”

Section: Determination Of the Aggregate Fraction And Quantum Yields Omentioning

confidence: 99%

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Improving the Quantum Yields of Perylene Diimide Aggregates by Increasing Molecular Hydrophobicity in Polar Media

Austin

Mylon

et al. 2017

ChemPhysChem

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Here we report the quantum yield of four aggregated perylene diimide (PDI) species that vary by the length of the branched side chains attached at the N,N' imide positions. The PDI molecules were dissolved in binary water:methanol solvents as a means to vary the solvent polarity and control the degree of aggregation in solution. By performing spectroscopy, kinetics, and light scattering experiments, the nature of the molecular interactions in the solutions was determined. The maximum quantum yield of the aggregated molecules increased from 0.04 for the shortest chain molecule (B2) to 0.20 for the largest chain molecule (B13). The higher quantum yield of B13 compared with B2 correlates well with an increase in the fluorescence lifetime. The monomer emission lifetime was 4.8 ns whereas a lifetime as high as 21.2 ns was measured for the B13 aggregate fluorescence. A shorter sub-nanosecond lifetime was also measured for suspended colloids in B5, B9, and B13. The enhanced quantum yield is attributed to an increase of disorder in the B13 aggregates. As the polarity of the solution increases, the hydrophobic effect further enhances the disorder, and, therefore, the quantum yields in these particles.

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Section: Resultsmentioning

confidence: 97%

Section: Determination Of the Aggregate Fraction And Quantum Yields Omentioning

confidence: 99%

Improving the Quantum Yields of Perylene Diimide Aggregates by Increasing Molecular Hydrophobicity in Polar Media

Austin

Mylon

et al. 2017

ChemPhysChem

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“…A feature of the Y OTs values in Table 6 is that the effect of replacing progressively H by Me in MeOH is to lower Y OTs by approximately 1.0. For primary alcohols, there is a good correlation between E T (30) and the molar concentration of alcohol [65] ; deviations of i-PrOH and t-BuOH from the plot may indicate an enhanced steric effect, further lowering the number of OH groups at the reaction site.…”

Section: N Ots Values For Alcoholsmentioning

confidence: 99%

Positioning solvolyses within the S_N2‐S_N1 and S_N3‐S_N2 spectrum of reaction mechanisms

Bentley

Choi

Koo

et al. 2016

J of Physical Organic Chem

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A simple linear regression (Q equation) is devised to position solvolyses within the established SN2‐SN1 spectrum of solvolysis mechanisms. Using 2‐adamantyl tosylate as the SN1 model and methyl tosylate as the SN2 model, the equation is applied to solvolyses of ethyl, allyl, secondary alkyl and a range of substituted benzyl and benzoyl tosylates. Using 1‐adamantyl chloride as the SN1 model and methyl tosylate as the SN2 model, the equation is applied to solvolyses of substituted benzoyl chlorides in weakly nucleophilic media. In some instances, direct correlations with methyl tosylate were employed. Grunwald–Winstein l values and kinetic solvent isotope effects are also used to locate solvolyses within the spectrum of mechanisms. Product selectivities (S) for solvolyses at 50 °C of p‐nitrobenzyl tosylate in binary mixtures of alcohol–water and of alcohol–ethanol for five alcohols (methanol, ethanol, 1‐propanol and 2‐propanol and t‐butanol) are reported and show the expected order of solvent nucleophilicity (RCH2OH > R2CHOH > R3COH). The data support the original assignments establishing the NOTs scale of solvent nucleophilicity. Copyright © 2016 John Wiley & Sons, Ltd.

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“…13 The work of Halle, especially, casts considerable doubt on the applicability of intermolecular NOE measurements; as such, it has potentially far-reaching consequences and has raised objections that clearly deserve an answer.…”

Section: Introductionmentioning

confidence: 98%

Nuclear Spin Relaxation Driven by Intermolecular Dipolar Interactions: The Role of Solute−Solvent Pair Correlations in the Modeling of Spectral Density Functions

2006

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Nuclear spin relaxation provides useful information related to the dynamics of molecular systems. When relaxation is driven by intermolecular dipolar interactions, the relevant spectral density functions (SDFs) also have significant contributions, in principle, from distant spins all over the dynamic range typically probed by NMR experiments such as NOESY. In this work, we investigate the intermolecular dipolar spin relaxation as driven by the relative diffusion of solvent and solute molecules taking place under a central force field, and we examine the relevant implications for (preferential) solvation studies. For this purpose, we evaluate the SDFs by employing a numerical approach based on spatial discretization of the time-propagation equation, and we supply an analytical solution for the simplest case of a steplike mean-field potential. Several situations related to different solute-solvent pair correlation functions are examined in terms of static/dynamic effects and relaxation modes, and some conclusions are drawn about the interpretation of NOE measurements. While we confirm previous results concerning the spoiling effect of long-range spins (Halle, B. J. Chem. Phys. 2003, 119, 12372), we also show that SDFs are sufficiently sensitive to pair correlation functions that useful, yet rather complicated, inferences can be made on the nature of the solvation shell.

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Role of hydroxyl concentrations in solvatochromic measures of solvent polarity of alcohols and alcohol–water mixtures—evidence that preferential solvation effects may be overestimated

Cited by 28 publications

References 48 publications

Improving the Quantum Yields of Perylene Diimide Aggregates by Increasing Molecular Hydrophobicity in Polar Media

Improving the Quantum Yields of Perylene Diimide Aggregates by Increasing Molecular Hydrophobicity in Polar Media

Positioning solvolyses within the S_N2‐S_N1 and S_N3‐S_N2 spectrum of reaction mechanisms

Nuclear Spin Relaxation Driven by Intermolecular Dipolar Interactions: The Role of Solute−Solvent Pair Correlations in the Modeling of Spectral Density Functions

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Role of hydroxyl concentrations in solvatochromic measures of solvent polarity of alcohols and alcohol–water mixtures—evidence that preferential solvation effects may be overestimated

Cited by 28 publications

References 48 publications

Improving the Quantum Yields of Perylene Diimide Aggregates by Increasing Molecular Hydrophobicity in Polar Media

Improving the Quantum Yields of Perylene Diimide Aggregates by Increasing Molecular Hydrophobicity in Polar Media

Positioning solvolyses within the SN2‐SN1 and SN3‐SN2 spectrum of reaction mechanisms

Nuclear Spin Relaxation Driven by Intermolecular Dipolar Interactions: The Role of Solute−Solvent Pair Correlations in the Modeling of Spectral Density Functions

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Positioning solvolyses within the S_N2‐S_N1 and S_N3‐S_N2 spectrum of reaction mechanisms