Enhanced Molecular Multipole Moments and Solvent Structure in Supercritical Carbon Dioxide

Saharay, Moumita; Balasubramanian, Sundaram

doi:10.1002/cphc.200400252

Cited by 30 publications

(37 citation statements)

References 39 publications

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“…9 The predicted value was ∼0.15 D. By using an average structure from the present BOMD (d(C-O) = 1.175 Å; θ(O-C-O) = 174 • ), our estimates for the dipole moment of scCO 2 are 0.17 D (QM) and 0.23 D (CHELPG charges). In a further investigation on the enhancement of molecular multipole moments in scCO 2 , Saharay and Balasubramanian 10 reported values for both the dipole and quadrupole moments of scCO 2 . The average values were ⟨µ⟩ = 0.85 D and ⟨Θ⟩ = −6.1 D Å.…”

Section: The Electric Dipole and Quadrupole Moments Of The Co 2 Monommentioning

confidence: 97%

“…Recent researches also emphasize the interest in the combination of subcritical and supercritical CO 2 with ionic liquids 6 which may lead to the design of sophisticated multiphasic reaction environments. 6 Numerous investigations on the structure, [9][10][11][12][13][14][15][16][17][18][19] dynamics, 9,17 Raman spectrum, [20][21][22][23] and thermochemical properties 24-31 of CO 2 were reported. A very recent work discusses the absorption of CO 2 in a protic ionic liquid.…”

Section: Introductionmentioning

confidence: 99%

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A first principles approach to the electronic properties of liquid and supercritical CO2

Cabral

Rivelino

Coutinho

et al. 2015

The Journal of Chemical Physics

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The electronic absorption spectra of liquid and supercritical CO2 (scCO2) are investigated by coupling a many-body energy decomposition scheme to configurations generated by Born-Oppenheimer molecular dynamics. A Frenkel exciton Hamiltonian formalism was adopted and the excitation energies were calculated with time dependent density functional theory. A red-shift of ∼ 0.2 eV relative to the gas-phase monomer is observed for the first electronic absorption maximum in liquid and scCO2. The origin of this shift, which is not very dependent on deviations from the linearity of the CO2 molecule, is mainly related to polarization effects. However, the geometry changes of the CO2 monomer induced by thermal effects and intermolecular interactions in condensed phase lead to the appearance of an average monomeric electric dipole moment〈μ〉= 0.26 ± 0.04 D that is practically the same at liquid and supercritical conditions. The predicted average quadrupole moment for both liquid and scCO2 is〈Θ〉= - 5.5 D Å, which is increased by ∼ -0.9 D Å relative to its gas-phase value. The importance of investigating the electronic properties for a better understanding of the role played by CO2 in supercritical solvation is stressed.

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Section: The Electric Dipole and Quadrupole Moments Of The Co 2 Monommentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

A first principles approach to the electronic properties of liquid and supercritical CO2

Cabral

Rivelino

Coutinho

et al. 2015

The Journal of Chemical Physics

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“…Despite the reported enhancement of induced molecular multipole moments in the supercritical phase [4], scCO 2 is less capable to dissolve polar solutes. The addition of small amounts of co-solvent to scCO 2 has been shown to enrich its solvent power towards polar solutes [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 87%

Ab initio molecular dynamics investigations of structural, electronic and dynamical properties of water in supercritical carbon dioxide

Saharay

Balasubramanian

2009

Indian J Phys

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Ab initio molecular dynamics simulations of a solitary perdeuterated water molecule solvated in supercritical carbon dioxide have been performed along an isotherm at three different densities. Electron donoracceptor interactions between the oxygen atom of water and the carbon atom of CO 2 as well as hydrogen bonded interactions between the two molecules have been shown to play a dominant role in the solvation. The mean dipole moment of the water molecule increases with the density of the solution, from a value of 1.85 D at low density to around 2.15 D at the highest density. The increase in the solvent density causes the water molecule to exhibit a range of behavior, from a free molecule to one that interacts strongly with CO 2 . A blue shift in the bending mode of water has been observed with increasing solvent density. The carbon dioxide molecules which are present in the first neighbor shell of water are found to exhibit larger propensity to deviate from a linear geometry in their instantaneous configurations.

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“…Unlike conventional liquids, the density of the supercritical fluid can even be doubled by doubling the pressure (Clifford 1999) which is a characteristic feature of compressible fluids. scCO 2 has been widely studied by researchers (Clarke et al 1997;Nagashima et al 2003) as also simulations in the pure state (Chen et al 2001;Salaniwal et al 1999Salaniwal et al , 2001Senapati et al 2004;Saharay and Balasubramanian 2004a and in the mixture (Saharay and Balasubramanian 2006).…”

Section: Introductionmentioning

confidence: 98%

“…the difference between the components that are parallel and perpendicular to the CO 2 backbone) of CO 2 is also much larger than, say, that of HCl. Thus, near neighbour interactions in a inhomogeneous solvation shell can induce an instantaneous dipole moment in CO 2 (Saharay and Balasubramanian 2004a). Several experimental and simulation studies have been carried out to estimate the extent of this type of interaction on the stabilization energies of CO 2 clusters (Illies et al 1987;Jucks et al 1987;Nesbitt 1988;Weida and Nesbitt 1996;Tsuzuki et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Ab initio studies on [bmim][PF6]-CO2 mixture and CO2 clusters

2008

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Ab initio molecular dynamics studies have been carried out on the room temperature ionic liquid, 1,n-butyl,3-methylimidazolium hexafluorophosphate ([bmim][PF 6 ]) and supercritical carbon dioxide mixture at room temperature and experimental density. Partial radial distribution functions (RDF) for different sites have been computed to see the organization of CO 2 molecules around the ionic liquid. Several partial RDFs around the carbon atom of CO 2 molecule are compared to find out that the CO 2 has specific interaction with a carbon atom present in the imidazolium ring. The CO 2 is also found to be very well organized around the terminal carbon atom of the butyl chain. The partial RDFs for the oxygen atoms around oxygen and carbon atoms of the CO 2 suggests that there is very good organization of CO 2 molecules around themselves even in the [bmim][PF 6 ] -CO 2 mixture. The instantaneous quadrupole moment tensor has been calculated for the anion and the cation. The ensemble average of diagonal components of quadrupole moment tensor of the cation have finite values, whereas the off-diagonal components of the cation and both the diagonal and off-diagonal components of the anion have the value of zero with a large standard deviation. The CPMD studies performed on CO 2 clusters reveals the greater tendency of the clusters with more CO 2 units, to deviate from the linear geometry.

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Enhanced Molecular Multipole Moments and Solvent Structure in Supercritical Carbon Dioxide

Cited by 30 publications

References 39 publications

A first principles approach to the electronic properties of liquid and supercritical CO2

A first principles approach to the electronic properties of liquid and supercritical CO2

Ab initio molecular dynamics investigations of structural, electronic and dynamical properties of water in supercritical carbon dioxide

Ab initio studies on [bmim][PF6]-CO2 mixture and CO2 clusters

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