Explicit hydration of ammonium ion by correlated methods employing molecular tailoring approach

Singh, Gurmeet; Verma, Rahul; Wagle, Swapnil; Gadre, Shridhar R.

doi:10.1080/00268976.2017.1310326

Cited by 7 publications

(4 citation statements)

References 37 publications

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“…An “ab initio” quantum computational study of PFOA/H 2 O system reported that on average eight water molecules can be accommodated near the polar headgroup of the PFO – ion . The reported hydration numbers for NH 4 + ion vary widely from 4 to 11. , On the basis of the reported hydration numbers for NH 4 + ion and PFO – ion, we fixed N H = 12.…”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

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Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

et al. 2021

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The self-assembly of surfactants in aqueous solution can be modulated by the presence of additives including urea, which is a well-known protein denaturant and also present in physiological fluids and agricultural runoff. This study addresses the effects of urea on the structure of micelles formed in water by the fluorinated surfactant perfluoro-n-octanoic acid ammonium salt (PFOA). Analysis of small-angle neutron scattering (SANS) experiments and atomistic molecular dynamics (MD) simulations provide consensus strong evidence for the direct mechanism of urea action on micellization: urea helps solvate the hydrophobic micelle core by localizing at the surface of the core in the place of some water molecules. Consequently, urea decreases electrostatic interactions at the micelle shell, changes the micelle shape from prolate ellipsoid to sphere, and decreases the number of surfactant molecules associating in a micelle. These findings inform the interactions and behavior of surface active per-and polyfluoroalkyl substances (PFAS) released in the aqueous environment and biota.

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Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

“…65 The reported hydration numbers for NH 4 + ion vary widely from 4 to 11. 66,67 On the basis of the reported hydration numbers for NH 4 + ion and PFO − ion, we fixed N H = 12.…”

Section: ■ Experimental and Theoretical Methodsmentioning

confidence: 99%

Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

et al. 2021

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“…Considering the volume contributions from one CF 2 group, surfactant headgroups, counterions, fraction of PEO homopolymer in the shell, and associated water molecules, the micelle shell volume can be written as where V CF 2 , V COO – , V NH 4 + , V D 2 O , and V EO are the volumes of the CF 2 group, PFOA headgroup, counterion NH 4 + , D 2 O molecule, and ethylene oxide monomer, respectively, α = Z / N agg is the fractional charge on a micelle ( Z is the charge on a micelle), N H is the hydration number of a surfactant molecule, n EO is the number of EO segments in the micelle shell, and N H,EO are the water molecules (hydration number) per EO segment in the micelle shell. On the basis of the reported hydration numbers for the NH 4 + ion , and PFO – ion, we fixed N H = 12. In addition, we fixed N H,EO = 4.6 based on our SANS results of 3% PEO 10000 in D 2 O considering the correlation length model.…”

Section: Methodsmentioning

confidence: 99%

Binding of Perfluorooctanoate to Poly(ethylene oxide)

et al. 2022

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To inform the design of polymer-based adsorbent materials for sequestration of per- and polyfluoroalkyl substances (PFAS) from aqueous solution, we report here on the critical aggregation concentration (CAC), shape, size, composition, and interactions of assemblies formed in water between perfluorooctanoic acid ammonium salt (PFOA) and the nonionic polymer poly(ethylene oxide) (PEO), obtained from complementary experiments (conductivity, surface tension, pyrene fluorescence, viscosity, and small-angle neutron scattering (SANS)) and atomistic molecular dynamics (MD) simulations. PEO–PFAS binding commences at concentrations lower than the PFOA critical micelle concentration (CMC) and is driven by PEO localizing on the micelle surface and shielding the fluorocarbon parts of PFOA from contact with water. PFOA + PEO mixed micelles have a 10% higher association number and are 40% more elongated compared to polymer-free PFOA micelles. This is the first investigation on the structure of polymer + fluorocarbon surfactant mixed micelles and contributes fundamental insights into the association of water-soluble polymers with PFAS surfactants.

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“…The geometry of the ammonia‐water cluster, (H 2 O) 4 ‐(NH 3 ) 3, is generated by us. The last test cluster, namely, (H 2 O) 8 ‐(NH 4 + ) formed by eight water molecules encapsulating a single NH 4 + ion, is adopted from Singh et al 30 The geometry of the single phenol and 12 acetylene cluster is taken from Kabadi et al 31 We also use a homo‐cluster, containing five carbonyl sulfide (OCS) molecules 32 for testing purpose. The Cartesian coordinates (in Å) of the test system are provided in the supplementary information (cf.…”

Section: Methodsmentioning

confidence: 99%

Development and testing of an algorithm for efficient MP2/CCSD(T) energy estimation of molecular clusters with the 2–body approach

Khire

Gadre

2022

J Comput Chem

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This work reports the development and testing of an automated algorithm for estimating the energies of weakly bound molecular clusters employing correlated theory. Firstly, the monomers and dimers of (homo/hetero) clusters are identified, and the sum of one‐body and two‐body contributions to correlation energy is calculated. The addition of this contribution to the Hartree‐Fock full calculation (FC) energies provides a good estimate of the total energies at Møller–Plesset second‐order perturbation theory (MP2)/coupled‐cluster method with singles and doubles (CCSD) (T)‐level theory using augmented Dunning basis sets. The estimated energies for several test clusters show an excellent agreement with their FC counterparts, with a substantial wall‐clock time saving employing off‐the‐shelf hardware. Furthermore, the complete basis set (CBS) limit for MP2 energy computed using the two‐body approach also agrees with its CBS energy with its FC counterpart.

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Explicit hydration of ammonium ion by correlated methods employing molecular tailoring approach

Cited by 7 publications

References 37 publications

Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea

Binding of Perfluorooctanoate to Poly(ethylene oxide)

Development and testing of an algorithm for efficient MP2/CCSD(T) energy estimation of molecular clusters with the 2–body approach

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