DFT studies of Al–O Raman vibrational frequencies for aquated aluminium species

Lu, Bangmei; X, Jin; Tang, Jie; Bi, Shuping

doi:10.1016/j.molstruc.2010.07.012

Cited by 24 publications

(8 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Except for the simplest modeling cases like the partial solvation of γ-amino-butyric acid with 2–5 water molecules [ 76 ] or consideration of 3–8 water molecules during the HOCl catalyzed tautomerization of β-cyclopentadione [ 77 ], a considerably larger number of water molecules is generally required for reasonable modeling of the solvation sphere even for a small organic molecule. An impressive example was provided by Lu [ 78 ], who optimized the geometry of the Al(H 2 O) 6 3+ ·12 H 2 O hydrate at the B3LYP/6-31+G(d,p) level in a water continuum by the PCM method. The resulting structure was of nearly spherical symmetry, easily allowing for the formation of the water network.…”

Section: Methodsmentioning

confidence: 99%

“…Indeed, under the conditions where a monomer has a geometry and atomic charges equal to those which were derived for the elements of the optimized dimer, the monomer’s internal free energy must be, by definition, higher than that for the optimized, separate monomer in water. Thus a correction (not carried out in [ 78 ]) must diminish the difference in the minimum G values upon the two approaches.…”

Section: Conformational Equilibriamentioning

confidence: 99%

See 1 more Smart Citation

Competing Intramolecular vs. Intermolecular Hydrogen Bonds in Solution

Nagy

2014

IJMS

145

View full text Add to dashboard Cite

A hydrogen bond for a local-minimum-energy structure can be identified according to the definition of the International Union of Pure and Applied Chemistry (IUPAC recommendation 2011) or by finding a special bond critical point on the density map of the structure in the framework of the atoms-in-molecules theory. Nonetheless, a given structural conformation may be simply favored by electrostatic interactions. The present review surveys the in-solution competition of the conformations with intramolecular vs. intermolecular hydrogen bonds for different types of small organic molecules. In their most stable gas-phase structure, an intramolecular hydrogen bond is possible. In a protic solution, the intramolecular hydrogen bond may disrupt in favor of two solute-solvent intermolecular hydrogen bonds. The balance of the increased internal energy and the stabilizing effect of the solute-solvent interactions regulates the new conformer composition in the liquid phase. The review additionally considers the solvent effects on the stability of simple dimeric systems as revealed from molecular dynamics simulations or on the basis of the calculated potential of mean force curves. Finally, studies of the solvent effects on the type of the intermolecular hydrogen bond (neutral or ionic) in acid-base complexes have been surveyed.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Conformational Equilibriamentioning

confidence: 99%

Competing Intramolecular vs. Intermolecular Hydrogen Bonds in Solution

Nagy

2014

IJMS

145

View full text Add to dashboard Cite

show abstract

“…The latter two cases should be minor species in very alkaline conditions, as their dimerization from two Al(OH) 4 – would involve the release of one OH – and two OH – , respectively. Later DFT calculations on Al 2 O(OH) 6 2– obtained Raman frequencies of 510 and 699 cm –1 (close to experiment) and assigned the vibrations to the symmetric stretch of the Al–O–Al unit and to the Al–OH stretch, respectively . Additional studies predicted that the effect of ion pairing upon the Al–O stretching frequencies would be minimal (4 cm –1 ) but that the energetic preference of Al 2 O(OH) 6 2– versus Al 2 (OH) 8 2– may be highly sensitive to ion–ion interactionsthough this was only implied using a very simple gas-phase electrostatic embedding model .…”

Section: Introductionmentioning

confidence: 92%

Ab Initio Molecular Dynamics Reveal Spectroscopic Siblings and Ion Pairing as New Challenges for Elucidating Prenucleation Aluminum Speciation

et al. 2018

View full text Add to dashboard Cite

The characterization of prenucleation species is essential to understand crystallization mechanisms across many chemical systems and often involves the use of vibrational spectroscopy. Nowhere is this more evident than in the development of "green" aluminum processing technologies, where detailed understanding of the speciation of aluminum and its polynuclear analogues in highly alkaline, low water solutions is elusive. The aluminate anion Al(OH) predominates in alkaline conditions, yet equilibrium with dimeric species, either μ-oxo AlO(OH) or di-μ-hydroxo Al(OH), can be assumed. Using ab initio molecular dynamics with full solvation and the presence of counterions, this work reconciles previous contradictory studies that had concluded only a single species under relevant solution conditions. We reveal that the two dimers are energetically separated by 2 kcal/mol in pure water but that the stability of each can be reversed by ion pairing expected in saturated salt solutions. Simulated Raman and IR spectra for each species (accounting for anharmonicity and the fluctuating solvating environment) provide the first proof that the considered species are "spectroscopic siblings", whose multiple overlapping bands prevent definitive assertions in terms of speciation when compared to the experimental spectra. These observations are likely to hold in higher order aluminate oligomers and as such present a massive challenge toward understanding the crystallization mechanisms relevant to aluminum processing.

show abstract

“…Serious problems were met, however, by Crittenden et al [63] through the optimization γ-amino butyric acid surrounded by five water molecules. An opposite example was found in the literature by Lu et al [64], who successfully reoptimized the gas-phase Al(H 2 O) 6…”

Section: Explicit Solvent Methodsmentioning

confidence: 81%

Theoretical Calculations on the Conformational/Tautomeric Equilibria for Small Molecules in Solution

Nagy

2014

Biochem & Pharmacol

View full text Add to dashboard Cite

The prevailing conformation and/or tautomeric form of a species may affect the product in chemical reactions. Determination of the predominant ligand structure is also important in theoretical drug design, where the goal is finding the best fit between the structurally flexible ligand and the receptor. The present review surveys the computational problems encountered in structure determination of small organic molecules in solution. The discussed issues include the method of the geometry optimization, the needed level of theory and basis set, choice of the modeling parameters, and the determination of the relative standard chemical potentials for estimating the equilibrium constant in relation to the molar concentration of the participants through the chemical transformation.

show abstract

DFT studies of Al–O Raman vibrational frequencies for aquated aluminium species

Cited by 24 publications

References 76 publications

Competing Intramolecular vs. Intermolecular Hydrogen Bonds in Solution

Competing Intramolecular vs. Intermolecular Hydrogen Bonds in Solution

Ab Initio Molecular Dynamics Reveal Spectroscopic Siblings and Ion Pairing as New Challenges for Elucidating Prenucleation Aluminum Speciation

Theoretical Calculations on the Conformational/Tautomeric Equilibria for Small Molecules in Solution

Contact Info

Product

Resources

About