PDF Archive

Easily share your PDF documents with your contacts, on the Web and Social Networks.

Share a file Manage my documents Convert Recover PDF Search Help Contact



poster (12aug10) .pdf


Original filename: poster (12aug10).pdf
Title: Microsoft PowerPoint - poster (12aug10) [Compatibility Mode]
Author: forestk

This PDF 1.5 document has been generated by PScript5.dll Version 5.2.2 / Acrobat Distiller 10.1.15 (Windows), and has been sent on pdf-archive.com on 06/11/2015 at 20:19, from IP address 71.17.x.x. The current document download page has been viewed 535 times.
File size: 140 KB (1 page).
Privacy: public file




Download original PDF file









Document preview


Theoretical studies of lanthanide and actinide ion solvation and
aqueous phase ligand binding using implicit solvent models
Kaya Forest a,* and Sierra Rayne b
a

Introduction




Results and Discussion


improved modeling of solvation behavior for
lanthanides (Ln) and actinides (An) required to
enhance ore extraction technologies and design /
optimize waste treatment technologies
most theoretical work to date has used explicit first
solvation shells either in the gas phase or in an
implicit second solvation environment:

for example, a strictly equatorial explicit solvation shell (either water or other ligands)
in gas phase does not account for solvent interactions with axial oxygen atoms
 equatorial ligand binding changes U=O bond lengths and charge distributions that are not
accounted for if additional explicit solvent molecules and/or implicit solvent model are not used
 potentially less desirable to have partial explicit first solvent shell  use implicit model (less
costly) or add more explicit solvent molecules (more costly and potential sources of error
[conformational uncertainty])








need to be able to apply reliable implicit coupled first,
second, and bulk solvation shell models for less
computational cost and better solvation coverage
covering entire solvent accessible surface areas on
Ln / An complexes
current study benchmarks several common solvation
models with multiple levels of theory against
experimental free energies of solvation for Ln / An
cations with varying oxidation states
also include representative implicit solvation model
based calculations on [UO2]2+ and [NpO2]2+ aqueous
phase coordination free energies for two model
ligands

best combination of broad convergence success and
accuracy obtained with HF/SDDAll, TPSSh/SDDAll,
and MP2/SDDAll methods and the IEFPCM-UFF
solvent model
 CPCM solvent model gives effectively equivalent
results as IEFPCM-UFF
 SMD solvent model consistently underestimates
(overly negative solvG bias) 3+ Ln / An solvation
free energies
 no improvement in 
solvG prediction performance
in moving from HF/TPSSh/MP2 (SDDAll)
frequency calculations to higher level single-point
energies with the MP3, MP4(SDQ), CCD, CCSD,
and QCISD methods
normalized solvG errors for IEFPCM-UFF
competitive with “conventional” neutral and ionic
small main group ions and molecules: mean signed
errors (MSEs) ~ 2.0% to 2.5%, mean absolute errors
(MAEs) ~ 3.0% to 3.5%, and root mean squared
errors (RMSEs) ~ 4.5%
 SMD errors higher at ~7% to 8.5% (MSE) up to
~10% (RMSE)



solvG°

-950

La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr

-700

–259.9

MP2/SDDAll

–178.4

–290.9



(b) TPSSh/SDDAll

significantly different gas and aqueous phase
geometries at MP2/SDDAll level:

solvG°

2.387 Å 1.806 Å

-950

La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr

-700

172.2

176.4

(c) MP2/SDDAll

solvG°

-900
-850





La
Ce
Pr
Nd
Pm
Sm
Eu
Gd
Tb
Dy
Ho
Er
Tm
Yb
Lu
Ac
Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm
Md
No
Lr

-750
-700

58.3
gas phase

IEFPCM-UFF
MSE=20.9 kcal/mol
MAE=28.7 kcal/mol
RMSE=36.9 kcal/mol

-800



relative solvG errors (solvG) are lower (MSE~1 to
4 kcal/mol; MAE~22 to 27 kcal/mol), and about equal
between IEFPCM-UFF and SMD models  i.e.,
within solution, both models appear to perform
equally well
negligible difference in solvG for 4+ An cations
between HF and TPSSh model chemistries
-1650

(a) HF/SDDAll

(b) TPSSh/SDDAll

-1600
-1550
-1500
-1400
-1350



(a) HF/SDDAll
IEFPCM-UFF
MSE=2.2 kcal/mol
MAE=63.7 kcal/mol
RMSE=74.1 kcal/mol



(b) TPSSh/SDDAll
IEFPCM-UFF
MSE=54.8 kcal/mol
MAE=82.2 kcal/mol
RMSE=95.5 kcal/mol

-1450

[1] Gaussian 09, Revision A.02, Frisch, M.J.; Trucks, G.W.; Schlegel, H.B.; Scuseria, G.E.; Robb, M.A.; Cheeseman, J.R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G.A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.P.; Izmaylov, A.F.; Bloino, J.; Zheng, G.;
Sonnenberg, J.L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J.A.; Peralta, J.E.; Ogliaro, F.; Bearpark, M.; Heyd, J.J.; Brothers, E.; Kudin, K.N.; Staroverov, V.N.;
Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J.C.; Iyengar, S.S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, N.J.; Klene, M.; Knox, J.E.; Cross, J.B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R.E.; Yazyev, O.; Austin, A.J.;
Cammi, R.; Pomelli, C.; Ochterski, J.W.; Martin, R.L.; Morokuma, K.; Zakrzewski, V.G.; Voth, G.A.; Salvador, P.; Dannenberg, J.J.; Dapprich, S.; Daniels, A.D.; Farkas, O.; Foresman, J.B.; Ortiz, J.V.; Cioslowski, J.; Fox, D.J. Gaussian, Inc., Wallingford CT, 2009.

1.46

n-octanol
bromobenzene

log10 K(nap)a

solvent
diethyl ether

0.59

1.13

fluorobenzene

0.35

1.09

carbon tetrachloride

0.10

chloroform

0.88

n-nonane

–0.32

benzene

0.63

n-perfluorohexane

–1.76



addition of meta / para halogens on (nap) will
increase hydrophobicity (extraction efficiency), and
will only modestly reduce favorability of [UO2(nap)n]2+
complex formation:

Table 2. SPARC estimated meta- and para-halogenated
(nap-X) derivative partitioning constants (log K(nap-X))
between various organic solvents and water.
log10 K(nap-X)a
para-Cl
3.02

para-Br
3.36

meta-F
2.18

meta-Cl
3.06

meta-Br
3.40

2.38

2.74

1.53

2.39

2.76

bromobenzene

1.85

2.96

3.42

1.89

3.00

3.46

chloroform

1.69

2.62

2.97

1.73

2.66

3.01

benzene

1.41

2.45

2.86

1.45

2.49

2.90

(nap-X) derivative

2.508 Å 1.816 Å

IEFPCM-UFF
MSE=18.2 kcal/mol
MAE=26.8 kcal/mol
RMSE=35.5 kcal/mol

-750

log10 K(nap)a

dichloromethane

para-F
dichloromethane 2.14
1.51
n-octanol

much weaker complexation in aqueous phase, but
still favorable, using SMD implicit solvation model at
MP2/SDDAll level:

-850
-800

solvent

solvent

-900

experimental solvG taken from ref. [2-5]

References
and Notes

[UO2(nap)2]2+

–159.4

IEFPCM-UFF
MSE=17.9 kcal/mol
MAE=27.8 kcal/mol
RMSE=36.1 kcal/mol

-800

best solvents for [AnO2(nap)n]2+ (An=U, Np; n=1 ,2)
complex extraction from near-neutral aqueous
solution likely polar halogenated and alcohol
derivatives:

Table 3. Gas phase standard state (298.15 K, 1 atm)
coordination energies (coordE(g)) for [UO2(nap-X)]2+
complexes at the MP4(SDQ)/SDDAll//HF/SDDAll level of
theory. Values are in kcal/mol.

Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm

substantial number of DFT methods did not readily
converge many of the Ln / An cations in the solvent
models with the SDDAll basis set at expected
multiplicities and/or yielded consistently lower quality
solvG estimates for all solvent models: BHandH, BMK,
B3LYP, B3P86, CAM-B3LYP, HCTH407, LC-wPBE,
M06HF, M06L, M062X, MPW91PW91, PBE1PBE,
SVWN5, and tHCTH

[UO2(nap)]2+

HF/SDDAll





[UO2(nap)n]2+ (n=1, 2) complexes strongly favored in
gas phase:

Table 1. Gas phase standard state (298.15 K, 1 atm)
coordination free energies (coordG(g)) for [UO2(nap)n]2+
(n=1, 2) complexes. Values are in kcal/mol.

expt
IEFPCM-UFF
SMD

Th
Pa
U
Np
Pu
Am
Cm
Bk
Cf
Es
Fm



standard state (298.15 K) gas phase (1 atm) to
aqueous phase (1 M) solvation free energies (solvG)
were calculated for lanthanide (Ln) and actinide (An)
bare 3+ and 4+ cations having available experimental
data using various Hartree-Fock (HF), density
functional theory (BHandH, BMK, B3LYP, B3P86, CAMB3LYP, HCTH407, LC-wPBE, M06HF, M06L, M062X,
MPW91PW91, PBE1PBE, SVWN5, tHCTH, and
TPSSh), and Møller–Plesset perturbation theory (MP2,
MP3, and MP4(SDQ)) model chemistries, CCD and
CCSD coupled cluster approaches, and Quadratic CI
calculations with single and double substitutions
(QCISD) using several basis sets (SDD, SDDAll,
CRENBL ECP 1D Uncontracted, ANO-RCC, Stuttgart
RSC 1997 ECP Double Zeta, and Stuttgart RSC
Segmented/ECP Quadruple Zeta) and the IEFPCMUFF, CPCM, and SMD implicit solvation models



solvG for UO2 at HF/SDDAll and MP2/SDDAll
using SMD solvation model are –419.2 and –391.9
kcal/mol, respectively
 excellent agreement with experimental values of
–40260 and –42115 kcal/mol [6-8]
 PCM/CPCM 
solvG = –394.5 (HF) and –371.5
(MP2) kcal/mol
HF/SDDAll solvG for NpO22+ range from –394
(IEFPCM-UFF/CPCM) to –534 kcal/mol (SMD)
1,8-naphthyridine (“nap”) used as a model bidentate
ligand for gas and aqueous phase complexes with
[AnO2]2+ (An=U, Np)

-850

solvG°





(a) HF/SDDAll

calculations conducted with Gaussian 09 [1]
except for single point energies as noted, values are
standard state free energies (G) with zero-point and
thermal corrections; structures represent global minima
with no imaginary frequencies



Results and Discussion

2+

level of theory

-750





Figure 1. Comparison between experimental and
calculated solvG° for bare trivalent lanthanide and
actinide cations using the HF/SDDAll, TPSSh/SDDAll,
and MP2/SDDAll levels of theory with the IEFPCM-UFF
and SMD solvent models. Values are in kcal/mol.
-900

Methods

Ecologica Research
Kelowna, BC, Canada, V1Y 1R9

Results and Discussion

-950



b

Department of Chemistry, Okanagan College
Penticton, BC, Canada, V2A 8E1
* E-mail: kforest@okanagan.bc.ca

62.9
aqueous phase (SMD)

aqueous solvation increases U–N and U=O bond
lengths, expands the N–U–N angle, and linearizes
the O=U=O group

gas phase (nap) complexation with [NpO2]2+
substantially more favorable than with [UO2]2+:
–219.7 [NpO2(nap)]2+ vs. –159.4 [UO2(nap)]2+
kcal/mol at HF/SDDAll level of theory  selective
extractant?
(nap) pKa3.4  amine protonation not problematic
at near-neutral pH values
 c.f., some other aliphatic and aromatic amine
ligands: trimethylamine (pKa=9.81), pyridine
(pKa=5.14) that are fully or partially protonated
near pH 7  interferes with extraction

coordE(g)

(nap-X) derivative

coordE(g)

unsubstituted
para-F

–191.6

unsubstituted

–172.0

meta-F

–191.6
–166.2

para-Cl

–179.8

meta-Cl

–171.8

para-Br

–187.8

meta-Br

–179.4

coordE(g) increase of only 4 kcal/mol, with log K(nap-X) increase of up to 2.5
units (i.e., K(nap) extraction efficiency increase of >300-fold with minimal
energetic cost for complexation)


1,10-phenanthroline (“phen”) also potentially good
ligand for [AnO2(nap)n]2+ complexation:

Table 4. Coordination free energies (coordG(g)) for
[UO2(phen)]2+ complexes at the MP2/SDDAll level of
theory. Values are in kcal/mol.
gas phase

SMD aqueous phase

–204.8

–36.0

Acknowledgements
This work was made possible by the facilities of the Western
Canada Research Grid (WestGrid; www.westgrid.ca; project
100185), the Shared Hierarchical Academic Research
Computing Network (SHARCNET; www.sharcnet.ca; project
sn4612), and Compute/Calcul Canada.

[2] Goldman, S.; Morss, L.R. Can. J. Chem. (1975) 53, 2695-2700. [3] Choppin, G.R.; Jensen, M.P. In: Chemistry of the Actinide and Transactinide Elements; Morss, L.R., Ed.; Springer: Amsterdam, 2006. [4] Kuta, J.; Clark, A.E. Inorg. Chem. (2010) doi:10.1021/ic100623y. [5] Rizkalla, E.N.; Choppin, G.R. In:
Handbook on the Physics and Chemistry of Rare Earths; Gschneider, Jr., K. Eyring, L., Eds.: Elsevier Science Publishers: Amsterdam, 1991. [6] Cornehl, H.H.; Heinemann, C.; Marcalo, J.; Pires de Matos, A.; Schwarz, H. Angew. Chem. Int. Ed. Engl. (1996) 35, 891-894. [7] Marcus, Y. J. Inorg. Nucl. Chem.
(1975) 47, 493-501. [8] Gibson, H.K.; Haire, R.G.; Santos, G.; Marcalo, J.; Pires de Matos, A. J. Phys. Chem. A (2005) 109, 2768-2781.
a

partitioning constants for (nap) between pure water and various organic solvents estimated using SPARC (http://ibmlc2.chem.uga.edu/sparc/; September 2009 release w4.5.1529-s4.5.1529).


Document preview poster (12aug10).pdf - page 1/1

Related documents


PDF Document poster 12aug10
PDF Document environ sci technol 47 2013 4953
PDF Document khare2002
PDF Document untitled pdf document 3
PDF Document businessmodel2018
PDF Document 11n13 ijaet0313450 revised


Related keywords