Anomalous conformational behavior of short poly(oxyethylene) chains in water: An FT-IR spectroscopic study

Sagawa, Tatsuya

doi:10.1016/0167-7322(95)00883-x

Cited by 31 publications

(24 citation statements)

References 11 publications

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“…For conformers with a ḡ orientation of the central dihedral, the α-methyl group imposes restrictions on the available positions and orientations for these added water molecules not present in the other hydrophilic conformers. Similar conformational behavior with extremum in composition dependence was observed experimentally and later explained by simulation for some conformers of short PEO oligomers larger than DME. The effect was explained in terms of unfavorable dipole−dipole interactions of water molecules completing the hydration shell of the oligomer with other neighboring dipoles.…”

Section: Conformational Propertiessupporting

confidence: 82%

Molecular Dynamics Simulations of 1,2-Dimethoxypropane and 1,2-Dimethoxyethane in Aqueous Solution

Bedrov

Smith

1999

J. Phys. Chem. B

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We report on the thermodynamic properties, conformations, and local structure of aqueous solutions of 1,2dimethoxypropane (DMP) as a function of composition and temperature as obtained from molecular dynamics simulations and compare results with simulations of aqueous solutions of 1,2-dimethoxyethane (DME). The density of DMP/water solutions was found to be systematically lower than that for DME solutions of the same composition, reflecting the lower density of neat DMP compared to DME. The excess volume of DMP/ water solutions closely resembles that of DME/water solutions, indicating that the nature of DMP solvation is similar to that of DME. The magnitude and composition dependence of the self-diffusion coefficient of water and ether in the DMP/water solutions were also found to closely resemble those of DME/water solutions. As in DME/water solutions, the populations of DMP conformers with favorable dipole-dipole interactions between the ether and solvating water (i.e., hydrophilic conformers) were found to increase with increasing dilution (water content). The free energy of stabilization (relative to the respective ttt conformers) for hydrophilic conformers in dilute solution was found to be around 1.5 kcal/mol for both DME and DMP solutions. The local structure, e.g., pair distribution functions and extent of hydrogen bonding, is similar for the more dilute DMP and DME solutions. However, the intrinsically higher conformational energy of the hydrophilic DMP conformers results in a much lower fraction of these conformers for all solution compositions compared to DME solutions. At higher ether content, this leads to significantly greater clustering of water molecules in DMP solutions and is probably the principal reason for the disparate phase behavior seen for poly(ethylene oxide) and poly(propylene oxide).

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Section: Conformational Propertiessupporting

confidence: 82%

Molecular Dynamics Simulations of 1,2-Dimethoxypropane and 1,2-Dimethoxyethane in Aqueous Solution

Bedrov

Smith

1999

J. Phys. Chem. B

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“…Meot-Ner et al 29 examined the complexing of H + from the formation of intramolecular or intermolecular hydrogen bonds with glymes (monoglyme, diglyme or triglyme) and 0–3 water molecules by pulsed high-pressure mass spectrometry; they found that the bonding of H 3 O + typically involve two or three hydrogen bonds, and complexes of H + and H 3 O + can be stabilized by interactions with bond dipoles of free ether groups of glymes and crown ethers whilst such a stabilization is enhanced by the decreasing constraints on the geometries of polar groups. Anomalous conformational behaviors of short glymes [CH 3 (OCH 2 CH 2 ) m OCH 3 with m = 2–6] in water were studied by FT-IR 30 and Raman spectroscopy; 31 both methods indicate that poly(ethylene oxide) chain progressively prefers the gauche ( g ) conformation for the OCH 2 –CH 2 O segment at the first stage, but this direction of the conformational preference is reversed for concentrations lower than a particular solution composition. Such an anomaly can be attributed to specific interactions and/or structures relevant to the glyme-water system.…”

Section: Physicochemical and Metal Complexing Properties Of Glymesmentioning

confidence: 99%

“…triglyme and tetraglyme) and crown ethers (e.g. 18-crown-6, 15-crown-5 and 12-crown-4) in H 2 O and D 2 O; their results suggest that the hydration of crown ethers increases with their size and is predominated by the hydrophobic hydration of -CH 2groups; they also indicate that there is a subtle difference between the hydration of the -CH 2 CH 2 O-group in crown and straight-chain compounds, and the compressibility data reveal a more negative compressibility due to the addition of a -CH 2 CH 2 O-group to crown 23 Heat capacity at 25 C (J mol À1 K À1 ) E T (30), kcal mol À1 E N T Monoglyme 1.62, 75 1.61, 57 1.59, 76 1.71 (in benzene) 76 7.18, 77 7.20, 72 7.55 78 38.2 0.231 191.14 79…”

Section: General Propertiesmentioning

confidence: 99%

Glymes as versatile solvents for chemical reactions and processes: from the laboratory to industry

2014

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Glymes, also known as glycol diethers, are saturated non-cyclic polyethers containing no other functional groups. Most glymes are usually less volatile and less toxic than common laboratory organic solvents; in this context, they are more environmentally benign solvents. However, it is also important to point out that some glymes could cause long-term reproductive and developmental damages despite their low acute toxicities. Glymes have both hydrophilic and hydrophobic characters that common organic solvents are lack of. In addition, they are usually thermally and chemically stable, and can even form complexes with ions. Therefore, glymes are found in a broad range of laboratory applications including organic synthesis, electrochemistry, biocatalysis, materials, and Chemical Vapor Deposition (CVD), etc. In addition, glyme are used in numerous industrial applications, such as cleaning products, inks, adhesives and coatings, batteries and electronics, absorption refrigeration and heat pumps, as well as pharmaceutical formulations, etc. However, there is a lack of comprehensive and critical review on this attractive subject. This review aims to accomplish this task by providing an in-depth understanding of glymes’ physicochemical properties, toxicity and major applications.

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“…A series of the Raman and infrared spectroscopy experiments for the DME/water and low molecular weight PEO/water systems have been made by Matsuura and co-workers. − These investigations reveal that the tgt conformer of DME becomes the most favorable in water solution. The reported intensity ratios of gauche and trans orientations around the C−C bond will be discussed below in our analysis of DME conformations.…”

Section: Theory Experiment and Previous Simulationsmentioning

confidence: 99%

Molecular Dynamics Simulations of 1,2-Dimethoxyethane/Water Solutions. 1. Conformational and Structural Properties

1998

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Molecular dynamics simulations of solutions of 1,2-dimethoxyethane (DME) and water have been performed in order to investigate the conformations of DME and the local solution structure as a function of solution composition and temperature. The simulations employ a previously developed force field based upon ab initio quantum chemistry calculations of DME/water interactions. The DME conformer populations show a strong dependence on temperature and solution composition and are quite different in aqueous solutions from those found in the gas phase or neat liquid. An analysis of the dependence of the conformer population distribution on temperature allows us to estimate the relative free energies of solvation for different conformers in water solution, which are found to be primarily energetic in origin for dilute solutions. The conformation dependence of the solvation free energy, resulting in "hydrophilic" and "hydrophobic" conformers, is explained in terms of differences in polar interactions between DME and neighboring water molecules. Analysis of the local structure of water around different DME conformers reveals that the degree of DME/water hydrogen bonding is nearly independent of the DME conformer for dilute solutions. The extent of water/water hydrogen bonding is also found to be nearly independent of composition over a wide composition range. To maintain a nearly constant level of water-water hydrogen bonding with increasing DME concentration, water is not randomly distributed in the system on a nearest-neighbor length scale but rather tends to form clusters of 4-5 molecules. The entropic penalty associated with this water structure increases with increasing DME concentration and temperature, thereby increasing the free energy of hydrophilic conformers relative to hydrophobic conformers.

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Anomalous conformational behavior of short poly(oxyethylene) chains in water: An FT-IR spectroscopic study

Cited by 31 publications

References 11 publications

Molecular Dynamics Simulations of 1,2-Dimethoxypropane and 1,2-Dimethoxyethane in Aqueous Solution

Molecular Dynamics Simulations of 1,2-Dimethoxypropane and 1,2-Dimethoxyethane in Aqueous Solution

Glymes as versatile solvents for chemical reactions and processes: from the laboratory to industry

Molecular Dynamics Simulations of 1,2-Dimethoxyethane/Water Solutions. 1. Conformational and Structural Properties

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