DFT Studies on the Water-Assisted Synergistic Proton Dissociation Mechanism for the Spontaneous Hydrolysis Reaction of Al3+ in Aqueous Solution

Dong, Shaonan; Shi, Wen‐Jing; Zhang, Jing; Bi, Shuping

doi:10.1021/acsearthspacechem.7b00142

Cited by 19 publications

(10 citation statements)

References 56 publications

(92 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This study clarifies the dominant existing forms and transformation processes of the monomeric hydrolytic species in the four stages of Al 3+ hydrolysis reactions, and provides important reference for further study on the hydrolysis-polymerization and transformation mechanisms of aqueous Al species. As an extension of future research, the critical issues such as the proton and hydroxyl transfer mechanism in the Al 3+ hydrolysis reactions, − the interaction between the dehydration and deprotonation processes, and the effect of pH on the distributions of the Al 3+ hydrolysis products can be explored on the basis of our calculation results. The method used in this study to determine the favorable dehydration reactions of the hydrolytic Al 3+ species with appropriate solute–solvent interactions (named as the “one-by-one” method) , is expected to combine with molecular dynamics simulation methods in future studies .…”

Section: Discussionmentioning

confidence: 99%

²⁷Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al³⁺ Hydrolytic Species with Different Coordination Structures

Dong

Shi

Zhang

et al. 2019

ACS Earth Space Chem.

Self Cite

View full text Add to dashboard Cite

In this study, the 27 Al NMR chemical shifts and relative stabilities of monomeric Al 3+ hydrolytic species with different coordination structures in aqueous solution are systematically investigated by using the density functional theory quantum chemical cluster model (DFT-CM) at the B3LYP/6-311+G(d,p) level. The main work includes: the static configurations of 20 possible existing monomeric Al 3+ hydrolytic species from Al 3+ to Al(OH) 4 − are optimized, and their 27 Al NMR shieldings are calculated; the dehydration reaction pathways for typical monomeric Al 3+ hydrolytic species are modeled, and the dominant forms of the intermediate hydrolytic species of Al(OH) 2+ , Al(OH) 2 + , and Al(OH) 3 0 are analyzed based on the Gibbs free energy changes of the dehydration reactions. The important role of the tetracoordinated Al(H 2 O)-(OH) 3 0 in the formation mechanism of the polynuclear Keggin-Al 13 is discussed. This work provides valuable references for further studying the formation and transformation mechanisms of the aqueous monomeric and polymeric Al species.

show abstract

Section: Discussionmentioning

confidence: 99%

²⁷Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al³⁺ Hydrolytic Species with Different Coordination Structures

Dong

Shi

Zhang

et al. 2019

ACS Earth Space Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our recent DFT calculation study of the self‐hydrolysis reaction of Al 3+ (aq), a water‐assisted synergistic proton dissociation mechanism without the influence of external OH − is obtained . The energy barrier for this self‐hydrolysis pathway is calculated to be Δ

G_{298, normala}^{\neq}

= 44.2 kJ mol −1 , which is larger than the negative Δ

G_{298, normala}^{\neq}

for the OH − ‐induced deprotonation pathways in this work. Accordingly, the rapid external OH − ‐induced barrierless proton dissociation is proposed as the main reaction pathway for the forced hydrolysis of Al 3+ (aq).…”

Section: Resultsmentioning

confidence: 99%

Density functional theory studies on the external OH⁻‐induced barrierless proton dissociation mechanism for the forced hydrolysis reaction of Al³⁺(aq)

Dong

Shi

Zhang

et al. 2018

Int J of Quantum Chemistry

Self Cite

View full text Add to dashboard Cite

The forced hydrolysis reaction of aqueous aluminum ion (Al 3+ ) is of critical importance in Al chemistry, but its microscopic mechanism has long been neglected. Herein, density functional calculations reveal an external OH − -induced barrierless proton dissociation mechanism for the forced hydrolysis of Al 3+ (aq). Dynamic reaction pathway modeling results show that the barrierless deprotonations induced by the second-or third-shell external OH − proceed via the concerted proton transfer through H-bond wires connected to the coordinated waters, and the inducing ability of the external OH − decreases with increasing hydration layers between Al(H 2 O) 6 3+ and the external OH − . The OH − -induced forced hydrolysis mechanism of Al 3+ (aq) is quite different from its self-hydrolysis mechanism without OH − . The inducing ability is a unique characteristic of OH − , rather than other anions such as F − or Cl − .aluminium ion, barrierless proton dissociation, density functional theory, forced hydrolysis,The hydrolysis chemistry of aluminum (Al) is central to environmental science, human health and industry activities. [1][2][3] Extensive efforts have been devoted to exploring the self and forced hydrolysis reactions of Al 3+ (aq) in aqueous solution that form various monomeric and polymeric hydrolytic Al species. [4] Unlike the self-hydrolysis of Al 3+ (aq) in acidic solutions whose detailed reaction steps have been carefully studied using both experimental [5,6] and theoretical [7][8][9][10][11] methods, the microscopic reaction kinetics for the forced hydrolysis of Al 3+ (aq) under elevated pH conditions such as base titration is rarely considered, and the role of hydroxyl in the formation mechanisms of the hydrolytic Al species remains poorly understood. This has hindered the precision studies of the hydrolysis-polymerization mechanisms of Al species.Conventionally, the self-hydrolysis of Al 3+ (aq) is viewed as the spontaneous proton removal on Al 3+ inner-shell coordinated waters with the assistance of adjacent solvent water molecules, [12] while the forced hydrolysis of Al 3+ (aq) involves the participation of external OH − . The firstorder forced hydrolysis of Al 3+ (aq), which acts as the first reaction step in forming polymeric hydroxyl Al species upon base titration, is usually expressed as: [13,14] Al 3 + + OH − ! AlðOHÞ 2 +AlðH 2 OÞ 6 3 + + OH − ! AlðOHÞðH 2 OÞ 5 2 + + H 2 O:In aqueous solution, the Al 3+ ion exists mainly in the hydrated form of Al(H 2 O) 6 3+ rather than the naked Al 3+ , thus, Equation (2) is more suitable to describe the reaction in aqueous solution. The reaction may proceed via the pathway that a proton on an Al(H 2 O) 6 3+ inner-shell coordinated water dissociates and moves into OH − , or in other words, the external OH − captures the proton. Herein, this possible reaction pathway is modeled using the density functional theory-quantum chemical cluster model (DFT-CM) method, [15,16] in order to elucidate the molecular mechanism of the forced hydrolysis reaction of Al 3+ (aq) in aqueou...

show abstract

“…The gas phase supermolecule polarizable continuum model (GP-SM-PCM) clusters are constructed on the basis of the gas phase (GP) configuration of the Zundel cation to model the hydration shell structures of * H + in acidic aqueous solutions. 31,44 The two water molecules in the Zundel cation are considered as the inner-shell solvent water molecules of * H + . By adding explicit solvent water molecules around the GP Zundel cation, the gas phase supermolecule model (GP-SM) clusters are constructed to describe the short-range hydration structure of * H + .…”

Section: Methodsmentioning

confidence: 99%

“…30 It is assumed that the recrossing factor and the nonequilibrium factor are unit. 31,32 ). For the * H + rattling pathways (Fig.…”

Section: Explorations On the * H + (Aq) Transfer Mechanism In Watermentioning

confidence: 99%

See 1 more Smart Citation

The Rattling and Rotation Behaviours of the Hydrated Excess Proton in Water

Bi¹

2019

Preprint

Self Cite

View full text Add to dashboard Cite

The rattling and rotation behaviours of the hydrated excess proton (H+) in water are investigated using the density functional theory–quantum chemical cluster model (DFT-CM) method. The rattling pathways for the target proton *H+ between two adjacent O atoms in the form of Zundel configurations with symmetrical solvation environments are obtained. The zero-point contribution reduces the reaction energy barrier and enables the rattling to occur spontaneously at room temperature. The rotational behaviour of *H+ in the form of *H+·H2O* is found. Upon *H+·H2O* rotation, *H+ changes its position accompanied by concerted displacement of surrounding solvent water molecules and the breaking and formation of hydrogen bonds. The “*H+·H2O* rotating migration mechanism” is proposed for the proton transfer mechanism in water — the same *H+ migrates via *H+·H2O* rotation through void in solvent water, rather than different protons hopping along water hydrogen bond chains as known as the Grotthuss mechanism.

show abstract

DFT Studies on the Water-Assisted Synergistic Proton Dissociation Mechanism for the Spontaneous Hydrolysis Reaction of Al³⁺ in Aqueous Solution

Cited by 19 publications

References 56 publications

²⁷Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al³⁺ Hydrolytic Species with Different Coordination Structures

²⁷Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al³⁺ Hydrolytic Species with Different Coordination Structures

Density functional theory studies on the external OH⁻‐induced barrierless proton dissociation mechanism for the forced hydrolysis reaction of Al³⁺(aq)

The Rattling and Rotation Behaviours of the Hydrated Excess Proton in Water

Contact Info

Product

Resources

About

DFT Studies on the Water-Assisted Synergistic Proton Dissociation Mechanism for the Spontaneous Hydrolysis Reaction of Al3+ in Aqueous Solution

Cited by 19 publications

References 56 publications

27Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al3+ Hydrolytic Species with Different Coordination Structures

27Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al3+ Hydrolytic Species with Different Coordination Structures

Density functional theory studies on the external OH−‐induced barrierless proton dissociation mechanism for the forced hydrolysis reaction of Al3+(aq)

The Rattling and Rotation Behaviours of the Hydrated Excess Proton in Water

Contact Info

Product

Resources

About

DFT Studies on the Water-Assisted Synergistic Proton Dissociation Mechanism for the Spontaneous Hydrolysis Reaction of Al³⁺ in Aqueous Solution

²⁷Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al³⁺ Hydrolytic Species with Different Coordination Structures

²⁷Al NMR Chemical Shifts and Relative Stabilities of Aqueous Monomeric Al³⁺ Hydrolytic Species with Different Coordination Structures

Density functional theory studies on the external OH⁻‐induced barrierless proton dissociation mechanism for the forced hydrolysis reaction of Al³⁺(aq)