Ab initio computation of the enthalpies of some gas-phase hydration reactions

Bene, Janet E. Del; Mettee, Howard D.; Frisch, Michael J.; Luke, Brian T.; Pople, John A.

doi:10.1021/j100240a020

Cited by 147 publications

(51 citation statements)

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“…This gives a best estimate of 14.3 kcal/mol for the desorption energy of H 2 0 in H-ZSM-5 at 0 K. Thermal effects will cause this value to decrease, but it is unclear if the usual ideal gas corrections used in theoretical enthalpy calculations [19] are valid in the restricted environment of the zeolite i n t e r i o r . By comparison, the experimental enthalpy of adsorption, which was obtained from a Clausius-Clapeyron analysis of p(T) data between 357 and 435 K for a coverage of less than one molecule per acid site, was found to be 1 2 f l kcal/mol [SI.…”

Section: Cluster 3 Ismentioning

confidence: 97%

Computational studies of water adsorption in zeolites

Zygmunt

Curtiss

Iton

1995

Zeolites: A Refined Tool for Designing Catalytic Sites, Proceedings of the International Zeolite Symposium

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(email:We have performed high-level ab initio calculations using Hartree-Fock (HF) theory, MZller-Plesset perturbation theory (MP2), and density-functional theory (DFT) to study the geometry and energetics of the adsorption complex involving H 2 0 and the Brgnsted acid site in the zeolite H-ZSM-5. These calculations use aluminosilicate cluster models for the zeolite framework with as many as 28 T atoms (T=Si, Al). -We included geometry optimization in the local vicinity of the acid site at the MP2 and DFT levels of theory for the smallest cluster, while in the larger clusters this was done at the HF/6-31G(d) level of theory. We have also calculated corrections for zero-point energies, extensions to higher basis sets, and higher levels of electron correlation.Results for the adsorption energy and geometry of this complex are reported and compared with previous theoretical and experimental values.

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Section: Cluster 3 Ismentioning

confidence: 97%

Computational studies of water adsorption in zeolites

Zygmunt

Curtiss

Iton

1995

Zeolites: A Refined Tool for Designing Catalytic Sites, Proceedings of the International Zeolite Symposium

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“…The effect of zero point energy (ZPE) was corrected by using the HF/6-31G(d) frequencies, scaled by 0.8929. The theoretical values at 0 K (DH 0 ) were converted into affinities at 298 K (DH 298 ) by standard statistical thermodynamics relationships [32] calculated from the scaled HF/6-31G(d) vibrational frequencies.…”

Section: S)mentioning

confidence: 99%

Competition between π and Non‐π Cation‐Binding Sites in Aromatic Amino Acids: A Theoretical Study of Alkali Metal Cation (Li⁺, Na⁺, K⁺)–Phenylalanine Complexes

Siu

Ling

Tsang

2004

Chemistry A European J

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To understand the cation-pi interaction in aromatic amino acids and peptides, the binding of M(+) (where M(+) = Li(+), Na(+), and K(+)) to phenylalanine (Phe) is studied at the best level of density functional theory reported so far. The different modes of M(+) binding show the same order of binding affinity (Li(+)>Na(+)>K(+)), in the approximate ratio of 2.2:1.5:1.0. The most stable binding mode is one in which the M(+) is stabilized by a tridentate interaction between the cation and the carbonyl oxygen (O[double bond]C), amino nitrogen (--NH(2)), and aromatic pi ring; the absolute Li(+), Na(+), and K(+) affinities are estimated theoretically to be 275, 201, and 141 kJ mol(-1), respectively. Factors affecting the relative stabilities of various M(+)-Phe binding modes and conformers have been identified, with ion-dipole interaction playing an important role. We found that the trend of pi and non-pi cation bonding distances (Na(+)-pi>Na(+)-N>Na(+)-O and K(+)-pi>K(+)-N>K(+)-O) in our theoretical Na(+)/K(+)-Phe structures are in agreement with the reported X-ray crystal structures of model synthetic receptors (sodium and potassium bound lariat ether complexes), even though the average alkali metal cation-pi distance found in the crystal structures is longer. This difference between the solid and the gas-phase structures can be reconciled by taking the higher coordination number of the cations in the lariat ether complexes into account.

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“…[25] All thermodynamic values reported in this work were obtained under standard conditions with Gaussian 03W. [20] Corrections to basis set superposition errors (BSSE) are not reported for the following reasons: 1) the ultimate goal of this work is to identify qualitative correlations of relative interaction energies; 2) the basis functions of Equation (4) are wellbalanced; 3) complete counterpoise corrections of geometries and frequencies of this system are beyond the physical limit of 32-bit Gaussian 03W; and 4) counterpoise corrections do not systematically improve the accuracy of the calculations.…”

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confidence: 99%

First Principles Investigation of Noncovalent Complexation: A [2.2.2]‐Cryptand Ion‐Binding Selectivity Study

Burnette

2008

ChemPhysChem

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A first principles methodology, aimed at understanding the roles of molecular conformation and energetics in host-guest binding interactions, is developed and tested on a system that pushes the practical limits of ab initio methods. The binding behavior between the [2.2.2]-cryptand host (4,7,13,16,21,24-hexaoxa-1,10-diaza-bicyclo[8.8.8]hexacosane) and alkali metal cations (Li(+), Na(+), and K(+)) in gas, water, methanol, and acetonitrile is characterized. Hartree-Fock and density functional theory methods are used in concert with crystallographic information to identify gas phase, energy-minimized conformations. Gas phase free energies of binding, with vibrational contributions, are compared to solution-state binding constants through relative binding selectivity analysis. Calculated relative binding free energies qualitatively correlated with solution state experiments only after gas phase metal desolvation is considered. The B3LYP exchange-correlation functional improves theoretical correlations with experimental relative binding free energies. The relevance of gas phase calculations towards understanding binding in condensed phases is discussed. Natural bond orbital methods highlights previously unidentified intramolecular and intermolecular M(+)(222) chemistries, such as an intramolecular n'(O)-->sigma*(CH) hydrogen bond.

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Ab initio computation of the enthalpies of some gas-phase hydration reactions

Cited by 147 publications

References 2 publications

Computational studies of water adsorption in zeolites

Computational studies of water adsorption in zeolites

Competition between π and Non‐π Cation‐Binding Sites in Aromatic Amino Acids: A Theoretical Study of Alkali Metal Cation (Li⁺, Na⁺, K⁺)–Phenylalanine Complexes

First Principles Investigation of Noncovalent Complexation: A [2.2.2]‐Cryptand Ion‐Binding Selectivity Study

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Ab initio computation of the enthalpies of some gas-phase hydration reactions

Cited by 147 publications

References 2 publications

Computational studies of water adsorption in zeolites

Computational studies of water adsorption in zeolites

Competition between π and Non‐π Cation‐Binding Sites in Aromatic Amino Acids: A Theoretical Study of Alkali Metal Cation (Li+, Na+, K+)–Phenylalanine Complexes

First Principles Investigation of Noncovalent Complexation: A [2.2.2]‐Cryptand Ion‐Binding Selectivity Study

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Competition between π and Non‐π Cation‐Binding Sites in Aromatic Amino Acids: A Theoretical Study of Alkali Metal Cation (Li⁺, Na⁺, K⁺)–Phenylalanine Complexes