1,10-phenanthroline and non-symmetrical 1,3,5-triazine dipicolinamide-based ligands for group actinide extraction

Article abstract of DOI:10.1002/chem.201402266

The synthesis and evaluation of new extractants for spent nuclear fuel reprocessing are described. New bitopic ligands constituted of phenanthroline and 1,3,5-triazine cores functionalized by picolinamide groups were designed. Synthetic routes were investigated and optimized to obtain twelve new polyaza-heterocyclic ligands. In particular, an efficient and versatile methodology was developed to access non-symmetric 2-substituted-4,6-di(6- picolin-2-yl)-1,3,5-triazines from the 1,3,5-triazapentadiene precursor in the presence of anhydride reagents. Extraction studies showed the ability of both ligand series to extract and separate actinides selectively at different oxidation states (U^VI, Np^V,VI, Am^III, Cm ^III, and Pu^IV) from an acidic solution (3 M HNO ₃). Phenanthroline-based ligands show the most promising efficiency for use in the group actinide extraction (GANEX) process due to a higher number of donor nitrogen atoms and a suitable pre-organization of the dipicolinamide-1,10-phenanthroline architecture. Actinides/lanthanides extraction: The synthesis and evaluation of new bitopic ligands constituted of poly-aza-aromatic units functionalized by amide groups for spent nuclear fuel reprocessing is described. Original synthetic routes were investigated to obtain the ligands (see figure).

Full text of DOI:10.1002/chem.201402266

DOI: 10.1002/chem.201402266
Full Paper
&
Actinides
1,10-Phenanthroline and Non-Symmetrical 1,3,5-Triazine
Dipicolinamide-Based Ligands For Group Actinide Extraction
Julia Bisson,[a, b] Jꢀrꢀmy Dehaudt,[b] Marie-Christine Charbonnel,[a] Denis Guillaneux,[a]
Manuel Miguirditchian,[a] Cꢀcile Marie,[a] Nathalie Boubals,[a] Guy Dutech,[a] Muriel Pipelier,[b]
Virginie Blot,[b] and Didier Dubreuil*[b]
Abstract: The synthesis and evaluation of new extractants
for spent nuclear fuel reprocessing are described. New bi-
topic ligands constituted of phenanthroline and 1,3,5-tri-
azine cores functionalized by picolinamide groups were de-
signed. Synthetic routes were investigated and optimized to
obtain twelve new polyaza-heterocyclic ligands. In particular,
an efficient and versatile methodology was developed to
access non-symmetric 2-substituted-4,6-di(6-picolin-2-yl)-
1,3,5-triazines from the 1,3,5-triazapentadiene precursor in
the presence of anhydride reagents. Extraction studies
showed the ability of both ligand series to extract and sepa-
rate actinides selectively at different oxidation states (UVI,
NpV,VI, AmIII, CmIII, and PuIV) from an acidic solution (3m
HNO3). Phenanthroline-based ligands show the most promis-
ing efficiency for use in the group actinide extraction
(GANEX) process due to a higher number of donor nitrogen
atoms and a suitable pre-organization of the dipicolinamide-
1,10-phenanthroline architecture.
Introduction
products. The separation of light actinides (U, Np, and Pu)
from fission products can be achieved by exploiting the great-
er affinity of the higher oxidation states of the light 5f ele-
ments to hard Lewis bases (according to the Pearson Hard Soft
Acid Base (HSAB) classification),[3] to form largely electrostatic
bonds with alkylamide or alkylphosphate ligands (i.e., tri-n-
butyl phosphate).[4] However transplutonium actinides (AmIII
and CmIII) and lanthanide(III) cations display very similar physi-
cochemical properties.[5] Nevertheless, previous studies have
shown that soft sulfur,[6] and nitrogen donors like tridentate
N-donor aromatic cores, are efficient extractants for AnIII/LnIII
separations because they are expected to form bonds with
a slightly greater covalent character with actinides than with
lanthanides.[4]
The separation of actinides (U, Np, Pu, Am, and Cm) from fis-
sion products (especially actinides(III) from lanthanides(III)) is
a key step in the reduction of radiotoxicity and thermal emis-
sions of ultimate nuclear waste. Light actinides (U and Pu) are
currently separated industrially from the final waste by solvent
extraction process (PUREX) and recycled after their conversion
to produce new fuel. Minor actinides (Np, Am, Cm) are also po-
tential fissile materials that could be recovered and recycled
along with major actinides in fast neutron reactors (Gen IV re-
actors).[1] Recycling of minor actinides will also decrease the
long-term radiotoxicity of the ultimate wastes. This concept,
called homogeneous recycling of actinides, is one of the strat-
egies being considered for future radioactive-waste manage-
ment.[2] In this field, the group actinides extraction (GANEX)
solvent extraction process is currently being intensively stud-
ied.
Considering the specific physicochemical properties of
minor and major actinides, our strategy deals with the devel-
opment of new bitopic extractants that combine amide
groups and aza-aromatic rings as complementary functional
units. Amide groups with hard-oxygen donors are expected to
improve the extraction of light actinides (U, Np, Pu) from
a highly acidic medium, whereas, aromatic soft nitrogen rings
should achieve AnIII/LnIII selectivity. Our groups have recently
reported the ability of bitopic terpyridine-based ligands to se-
parate UVI, PuIV, AmIII, CmIII, and NpV–VI by solvent extraction
with some encouraging selectivity for actinides versus lantha-
nides.[7] However, the extraction efficiency for AmIII remains too
weak for development at an industrial scale.
One of the main challenges of the GANEX process is to de-
velop new solvating ligands that can selectively extract major
and minor actinides together without affinity towards fission
[a] Dr. J. Bisson, Dr. M.-C. Charbonnel, Dr. D. Guillaneux, Dr. M. Miguirditchian,
Dr. C. Marie, N. Boubals, G. Dutech
CEA-Nuclear Division Energy, Radiochemistry & Process Department
30207 Bagnols-sur-Cꢀze (France)
[b] Dr. J. Bisson, Dr. J. Dehaudt, Dr. M. Pipelier, Dr. V. Blot, Prof. D. Dubreuil
Universitꢁ de Nantes, CEISAM UMR-CNRS 6230
UFR des Sciences et Techniques
To improve the design of our ligands, we thought of replac-
ing the central pyridine moiety of the terpyridine sequence by
either a 1,10-phenanthroline or a 1,3,5-triazine unit bearing
a variable group at the C2 center (Figure 1). 1,10-Phenanthro-
line was chosen for its rigidity and the juxtaposition of two ni-
2 rue de la Houssiniere BP 92208, 44322 Nantes Cedex 3 (France)
E-mail: didier.dubreuil@univ-nantes.fr
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201402266.
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trogen donor atoms, which are known to thermodynamically
favor complexation properties.[8] Central triazine rings were se-
lected to lower the ligand affinity towards protons compared
with the pyridine heterocycle, and thus favor metal complexa-
on the electronic effects on the extraction efficiency of poly-
aza-heterocycle ligands.
Results and Discussion
Ligand synthesis
The first challenge of this work was to develop fast and effi-
cient routes to produce targeted new bitopic ligands. Al-
though only a few limitations were expected in the prepara-
tion of 2,9-di(6-picolin-2-yl)-phenanthroline derivatives, the
synthesis of 2-substituted-4,6-di(6-picolin-2-yl)-1,3,5-triazines
was far from obvious due to the limited sets of methods de-
scribing the synthesis of non-symmetrical 2,4,6-substituted de-
rivatives in the literature.[12]
Figure 1. Structure of new phenanthroline- and triazine dipicolinamide-
Phenanthroline-based extractants
based ligands.
First, four new dipicolinamide phenanthroline-based ligands
were synthesized following two different routes from commer-
cially available 1,10-phenanthroline 5 (Scheme 1). Route I in-
tion in a highly acidic medium.[9] In this field, nitrogen-donor
aromatic bases such as 2,2’:6’2’’-terpyridine (tpy) and triazine
derivatives, in particular 2,6-di(5,6-dialkyl-1,2,4-triazin-3-yl)pyri-
dine (Rbtp), 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine (tptz), and
2-amino-4,6-di(pyridin-2-yl)-1,3,5-triazine (adptz), have already
been studied as interesting ligands.[10,11]
volves
a
conventional Stille coupling reaction from
2,9-dichlorophenanthroline 8 obtained in 3 steps according to
a literature procedure.[13] Ammonium intermediate 6, formed
by adding a large excess of 1,3-dibromopropane to phenan-
throline 5 in nitrobenzene, was oxidized by using K3[Fe(CN)6]
in basic aqueous solution to give the diketone 7 in 38% over-
all yield. 2,9-Dichlorophenanthroline 8 was then obtained in
88% yield by treating the diketone 7 with PCl5 in POCl3 at
110 8C. 2-(tributylstannyl)-6-picoline 9, prepared from 6-picoline
by a usual stannylation procedure,[14] was subsequently treated
with dichloride 8, dissolved in toluene, in the presence of
In the present study, we report the synthesis and solvent ex-
traction properties of new bitopic dipicolinamide N,O-ligands
in [1,10]-phenanthroline and 2-substituted-1,3,5-triazine series
(Figure 1). In the latter triazine series, we sought to explore the
possibility of introducing variable substituents at the C2 posi-
tion of the central heterocycle ring, which should shed light
Scheme 1. Routes to the synthesis of the phenanthroline-based ligands 1a–d.
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[Pd(PPh3)4] as a catalyst. Following this procedure, the 2,9-di(6-
picolin-2-yl)-1,10-phenanthroline 10 was isolated in 85% yield.
Despite the moderate yield of the oxidation step giving the
ketone 7 from 6, compound 10 could be relatively easily pre-
pared on a multigram scale.
the lack of a general efficient method to facilitate their
access.[12] Nevertheless, a few derivatives such as 2-amino-,[18]
2-hydroxy-,[18b] and 2-aryl-4,6-di(pyridin-2-yl)-1,3,5-triazine[19]
have been described in the literature from a common 2-cyano-
pyridine precursor and the procedures used were logically
evaluated to reach targeted 2-substituted-4,6-di(6-picolin-2-yl)-
1,3,5-triazine derivatives 15a–g from the 2-cyano-6-picoline
precursor (Scheme 2). As expected, Route III successfully afford-
Alternatively, the synthesis of dipicoline phenanthroline 10
was envisioned in a shorter route (two reaction steps) from
1,10-phenanthroline (Route II) following a similar procedure de-
scribed earlier by Sauvage and co-workers in the
pyridine series.[15] A first picoline residue was directly
introduced on the 1,10-phenanthroline 5 by reaction
of a slight excess of the 2-picoline-lithium reagent
11 and, re-aromatization, after hydrolysis, of the re-
sulting mono-substituted intermediate formed with
MnO2. The same procedure repeated from the result-
ing mono-substituted phenanthroline 12 led to the
expected dipicoline compound 10 in 34% overall
yield. In this reaction sequence, the 2-picoline-lithi-
um 11 was generated in situ from the 2-bromo-6-pi-
coline by halogen–metal exchange with n-BuLi at
À788C. Although disubstituted phenanthroline 10 is
advantageously accessible by Route II in only two
steps, unfortunately, in our hands, this procedure
cannot be scaled up at multigram scale because the
second arylation reaction proceeded with a signifi-
cant decrease in yield. Furthermore, attempts at the
direct diarylation organo-coupling in the presence of
almost 2 equivalents of picoline-lithium reagent 11
also failed.
Scheme 2. Synthesis of the 1,3,5-triazine-based 4,6-dipicoline derivatives 15a–g.
We thus pursued our investigation by the oxida-
tion of dipicoline phenanthroline 10 in the presence
of a large excess of SeO2 in pyridine affording the expected
diacid 13 in an almost quantitative manner after 5 days,
whereas a Jones oxidation using CrO3 in sulfuric acid solvent
did not result in the bis-oxidation of the dipicoline precursor
10.
From the 6,6’-(1,10-phenanthrolin-2,9-diyl)-2,2’-dipicolinic
acid 13, access to two series of dipicolinamide phenanthroline
ligands 1a–d bearing two identical N-alkyl groups, or an alkyl
and an aryl groups, was pursued. For this purpose a conven-
tional peptide coupling procedure was used involving activa-
tion of dicarboxylic acid 13 as acid chloride, by SOCl2 treat-
ment, prior to adding 2 equivalents of the corresponding
amine reagent in the presence of Et3N in CH2Cl2. The four new
dipicolinamide phenanthroline ligands 1a–d were then isolat-
ed after flash chromatography on silica gel in 52, 31, 58, and
58% yields, respectively.
ed the 2-phenyl-triazine derivative 15a (R=Ph) in 82% yield,
by treating 2-cyano-picoline 16 (2 equivalents) with the lithium
amidine salt of benzonitrile 14, generated in situ from benzoni-
trile and lithium dimethylamine (2m in THF) in Et2O.[19] Rou-
te IV, proposed by Wieprecht for the preparation of 2-amino-
and 2-hydroxy-dipyridinyltriazine derivatives,[18a] provided the
corresponding dipicoline triazine analogues 15b (R=NH2) and
15c (R=OH) in 71 and 54% yield, respectively, by reaction of
the corresponding amidine (e.g., guanidine for amino- and
urea for hydroxy-derivatives) with 2 equivalents of 2-cyano-
picoline 16.
Despite the possible access to triazines 15a and 15b–c by
Routes III and IV, respectively, unfortunately, both pathways are
limited by the poor diversity of commercially available re-
agents (nitriles and amidines) and therefore cannot be extend-
ed further to a large variety of 2-substituted-4,6-di(6-picolin-2-
yl)-1,3,5-triazines. For instance, procedure IV applied with tri-
fluoroacetamidine reagent gave the corresponding 2-trifluoro-
methyl-4,6-di(6-picolin-2-yl)-1,3,5-triazine 15d in a disappoint-
ingly low yield (6%).
Triazine-based extractants
Over the past 10 years, increasing attention has been paid to
pyridinyl-substituted triazine ligands and their complexes,
mostly due to their promising photophysical properties.[16]
Among them, particular interest has been focused on symme-
tric 2,4,6-tris-pyridine-1,3,5-triazine (TPTZ) ligands.[17] However,
heterocycle sequences containing a non-symmetrically substi-
tuted triazine ring have been rarely studied mainly because of
To develop a general method to access di(6-picolin-2-yl)-
1,3,5-triazines bearing variable groups at the C2 position, we
first investigated Pd-catalyzed cross-coupling methodologies,
widely applied to trichloro-s-triazine or 2,4-dichloro-6-methoxy-
s-triazine precursors.[20] However, in our hands, coupling reac-
tions using the 2-picoline metallic reagents in Stille, Suzuki–
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Miyaura, and Negishi processes failed to produce the disubti-
tuted target compounds in good yield (i.e., 6% by Stille cou-
pling).
Finally, Route V was found to be the best way to reach our
goal and was successfully extended to prepare 2-substituted-
4,6-dipicoline 1,3,5-triazines 15a–g. The strategy was inspired
by a procedure described by Stamford and Schaefer[21] in 1965
providing access to 2-, 4-, and 6-substituted-1,3,5-triazines by
treatment of acetic anhydride with trichloromethyltriazapenta-
diene intermediates. The preparation of the transient key-spe-
cies 2,4-di(6-picolin-2-yl)-1,3,5-triazapentadiene 19 was carried
out in two steps from the readily available 2-cyano-6-picoline
16 as shown in Scheme 2. Cyano-picoline 16 was first convert-
ed into the corresponding carboxamidine 18 in 80% yield by
treatment with sodium methoxide in methanol at room tem-
perature prior to the addition of ammonium chloride.[22] The
carboxamidine 18 was then treated with another equivalent of
2-cyano-6-picoline 16 in the presence of NaH, in DMSO at
room temperature, to give the expected 2,4-di(6-picolin-2-yl)-
1,3,5-triazapentadiene 19 in 62% yield. Following this process,
a number of C2-substituted dipicoline triazines can be ob-
tained from the same 1,3,5-triazapentadiene precursor 19 de-
pending on available anhydride reagents. To illustrate the pur-
pose, five 2-substituted-4,6-di(6-picolin-2-yl)-1,3,5-triazines
15a–g were formed (Table 1) using alkyl- (entries 4 and 5), het-
eroalkyl- (entry 3), aryl- (entry 1), and heteroaryl-anhydrides
Scheme 3. Preparation of 2-methoxy-4,6-(6-picolin-2-yl)-1,3,5-triazine 15i
from hydroxytriazine 15c.
The substitution of the chlorine group on 15h by a methoxy
group proceeded after addition of NaHCO3 (2 equivalents) in
a MeOH/H2O mixture (v/v=10:1) at 358C, allowing complete
conversion into the 2-methoxy-triazine 15i in 85% yield.
To summarize, Routes III, IV, and V have enabled the prepara-
tion of nine new di(6-picolin-2-yl)-1,3,5-triazine derivatives
bearing different substituents at the C2 position in good
yields. It has to be noted that obviously the developed proce-
dure should allow the preparation of trisubtituted 1,3,5-triazine
derivatives bearing differentiated groups at 2, 4, and 6 posi-
tions.
Table 1. Route V: Synthesis of 2-substituted-4,6-di(6-picolin-2-yl)-1,3,5-tri-
azines 15.
With a view to obtain the corresponding dicarboxylic acids
20a–i, two oxidation procedures were evaluated on the dipi-
colinyl-triazine derivatives 15a–i: in the presence of SeO2 or
through a Jones procedure using CrO3 in sulfuric acid (proce-
dures B and C, respectively, Scheme 4). Both methods were
Entry
Anhydride
Product
Yield
[%]
1
2
3
4
5
6
(C6H5ÀCO)2O
(CH3OÀCO)2O
(CF3ÀCO)2O
(CH3ÀCO)2O
(tBuÀCO)2O
(C5H4NÀCO)2O
15a R=Ph
15c R=OH
15d R=CF3
15e R=CH3
15 f R=tBu
15g R=C5H4N
93
81
86
95
90
82
(entry 6). All compounds were formed as a sole reaction prod-
uct isolated in good yields (81 to 95%) after purification by
chromatography on silica gel. The later procedure takes ad-
vantage of the fact that when the corresponding anhydride is
not commercially available (i.e., picolinic anhydride), simple ex-
isting synthetic methods can be used to prepare it.[23]
Scheme 4. Oxidation of 2-substituted-4,6-(dipicolin-2-yl)-1,3,5-triazines 15.
The use of dimethyldicarbonate (Table 1, entry 2), expected
to introduce a methoxy group at the C2 position of the tri-
azine, gave the hydroxytriazine derivative 15c, isolated as the
sole product of the reaction (81% yield). This result prompted
us to overcome the problem by using a halogeno intermedi-
ate. Thus, treating hydroxytriazine 15c in phosphoryl chloride
heated at reflux in the presence of N,N-diethylaniline for 3 h,
led to the formation of the 2-chloro-4,6-di(picolin-2-yl)-1,3,5-tri-
azine 15h in 51% yield (Scheme 3).[24] Triazine chloride 15h is
quite sensitive to hydrolysis and must be readily engaged in
the next step to avoid its degradation.
compared and the results are summarized in Table 2. Whereas
di-oxidation of dipicoline phenanthroline 10 by SeO2 was com-
pleted in pyridine heated at reflux (98% yield, see Scheme 2),
triazine substrates appeared much more sensitive depending
on the nature of the C2 substituent. Success was encountered
with SeO2 when the reactions were run at 808C (Table 2, en-
tries 1 and 7, 15a R=Ph and 15d R=CF3) avoiding the sub-
stantial degradation that occurs above this temperature.
However, selenium dioxide failed to oxidize electron-donat-
ing 2-substituted triazines (Table 2, entries 5, 9 and 11; 15c R=
OH, 15h R=Cl and 15i R=OMe, respectively) and CrO3 was
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azine 2c (10%) was mostly due to some purification difficulties
on silica gel due to the high lipophilicity of dioctylamine
groups. However, the method previously used in the phenan-
throline series provided the dipicolinamide triazine ligands 3a–
c and 4a–c in better yields from diacids 20a and 20d, respec-
tively (Table 3; entries 4–8). For this purpose, the latter dicar-
boxylic acids were dissolved in SOCl2, 2 h at 908C, prior to
adding the amine partners in the presence of Et3N (procedure
E).
Table 2. Results of oxidation procedures on 15a–i.
Entry
Substrate 15a–i
Product
Oxidation
procedure
Yield [%]
20a–i
1
2
3
4
5
6
7
8
B
C
B
C
B
C
B
C
B
C
B
C
91
–
–
76
15a R=Ph
15b R=NH2
15c R=OH
15d R=CF3
15h R=Cl
20a
20b
Not attempted
–
81
Not attempted
–
–
–
Eight new dipicolinamide triazine-based ligands 2a–c, 3a–
c and 4a,b were obtained in 44 to 58% yields.
20d
9
10
11
12
Solvent-extraction studies
15i R=OMe
Not attempted
Preliminary stability studies in an alcohol/water medium
Prior to extraction studies, ligand stability was evaluated in an
alcohol/water medium (MeOH/H2O) by UV/Visible and NMR
spectroscopic analyses recorded for each diethylamide deriva-
tives 2a, 3a, 4a, and 1a. Whereas no change was observed in
phenanthroline, in the amino-triazine and phenyl-triazine
series, the UV profile of both trifluoromethyl-triazine ligands
4a and 4b varied during the experiment time. A kinetic study
on 4a using 1H and 19F NMR spectroscopy in deuterated
MeOD/D2O medium confirms this phenomenon with appear-
ance of two new products. The similar chemical shifts of both
formed species suggested a similar structure (see data in the
Supporting Information). The nature of each species was deter-
mined by ESI-MS spectroscopy (see data in the Supporting In-
formation) indicating that, in a MeOH/H2O medium, regioselec-
tive nucleophilic addition of a methoxy or a hydroxyl residue
occurred on the C2 aromatic bond activated by the trifluoro-
methyl group (Figure 2). Consequently, these medium-sensitive
ligands cannot be useful in the extraction evaluations.
only efficient at room temperature on the 2-amino-di(6-picolin-
2-yl)-1,3,5-triazine 15b (entry 4; R=NH2) giving the corre-
sponding amino-triazine dicarboxylic acid 20b in a good 76%
yield.
Finally, the targeted dipicolinamide triazine ligands were ob-
tained from the corresponding dipicolinic acids 20a, 20b, and
20d by using two peptide-coupling procedures (Scheme 5).
The access to the dipicolinamide triazines 2a–c, in the amino-
Scheme 5. Procedures for amide formation on triazine ligands.
triazine series, was only performed in moderated yields follow-
ing an activation of the diacid 20b with a mixture of N-ethyl-
N’-(3-dimethylaminopropyl)carbodiimide (EDC) and 1-hydroxy-
benzotriazole (HOBt; procedure D), in the presence of amine
partners (diethylamine a, ethylphenylamine b or dioctylamine
c; Table 3; entries 1–3). The poor yield in the dipicolinamide tri-
Figure 2. Byproducts obtained when 4a stands in a MeOH/H2O medium.
Extraction tests on AmIII, CmIII, EuIII, and PuIV
Table 3. Amide formation on 6,6’-(2-substituted-1,3,5-triazine-4,6-diyl)-
2,2’-dipicolinic acid.
The extraction of actinides at different oxidation states (241AmIII,
244CmIII, and 239–240PuIV) from a 3m HNO3 solution was measured
with the lipophilic ligands 1c, 1d, 2c, and 3c dissolved in
n-octanol. Unfortunately, other ligands are not soluble enough
in n-octanol to be evaluated in such experiment. 152EuIII extrac-
tion was also tested to establish ligand selectivity towards lan-
thanides. The extraction data are summarized in Table 4 and
compared with those of N,N,N’,N’-tetraoctyl-6,6’-2,2’:6’,2“-ter-
pyridine diamide (te-tpyda). This ligand, previously studied in
our group,[7] was chosen as a reference due to its comparable
molecular structure.
Entry
Substrate Triazine
ligand
R
R1/R2
Procedure Yield
[%][a]
1
2
3
4
5
6
7
8
2a
NH2 ethyl/ethyl
NH2 ethyl/phenyl
NH2 octyl/octyl
D/E
D
D
E
E
E
58/0
54
10
44
59
56
55
58
20b
2b
2c
3a
3b
3c
4a
4b
Ph
ethyl/ethyl
ethyl/phenyl
octyl/octyl
ethyl/ethyl
ethyl/phenyl
20a
20d
Ph
Ph
CF3
CF3
E
E
[a] Purified product.
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with the extractant concentration was measured as previous
studies with similar molecules (diamidoterpyridines) have been
already reported with PuIV, AmIII, and CmIII, all consistent with
a 1:1 stoichiometry M ligand.[7] The acidity of the aqueous
phase was 2.6m after equilibrium, which gives a distribution of
HNO3 of 0.16 (mainly due to the partition between aqueous
HNO3 and n-octanol), which is consistent with previous data.[27]
Table 4. Distribution coefficients of actinides and EuIII by diamidopolyni-
trogen ligands and related separation factors.[a]
Extractant
1c
1d
2c
3c
te-tpyda[7]
[HNO3]eq [M]
DEu(III)
DAm(III)
DCm(III)
DPu(IV)
2.6
2.6
2.6
2.6
2.5
6.3ꢂ10À3 0.091
3.5ꢂ10À3 3.4ꢂ10À3 1.1ꢂ10À3
0.17
0.07
2.2
1.8
0.74
14.8
0.043
0.013
0.47
0.042
0.016
0.18
4.6ꢂ10À3
2.6ꢂ10À3
0.35
The range of ligand concentration was from 10À4 to 10À2
m
(limit of solubility in n-octanol).
SFAm/Eu/SFPu/Eu 27/350
20/162 12/157
12/53
5/320
The plot of the logarithms of DAm and DPu as a function of
the logarithm of the ligand concentration is presented in
Figure 3. As anticipated, the slopes close to 1, 0.95, and 1.06,
respectively, imply a 1:1 species for the extracted complexes.
init
[a] Extractant 0.01 molLÀ1 in n-octanol; cations as traces; [HNO3]aq.
3 molLÀ1, 25.08C)
=
Results shown that PuIV is the element most efficiently ex-
tracted (0.2<DPu(IV) <15) by all ligands and that AmIII and CmIII
are 10 to 400 times less extracted than PuIV. This higher affinity
towards Pu4+ could be related to the charge of the cation. The
replacement of the central pyridine by a triazine unit leads to
better extraction of AmIII and CmIII (10 fold higher than with
te-tpyda) whereas affinity towards EuIII and PuIV remains simi-
lar. A positive effect on PuIV extraction is also observed when
the triazine core is functionalized by a donor group (R=NH2
vs. Ph, see Scheme 5). The presence of a phenanthroline cen-
tral unit leads to better extraction of all actinides (for example,
DPu =2.2 and 14.8 vs. 0.35 for te-tpyda). This feature could be
explained by an increasing number of accessible nitrogen
donor atoms (4 for dipicoline phenanthroline instead of 3 for
the terpyridine sequence) associated with a suitable preorgani-
zation of the 2,9-di(6-picolin-2-yl)-[1,10]-phenanthroline archi-
tecture, inasmuch as the cis-locked [1,10]-phenantroline motif
is already favorable for cation complexation.[14]
Substituting an ethyl chain for a phenyl group on each
amide function, significantly enhanced the cation extraction ef-
ficiency as observed with 1c and 1d. The positive effect of
phenyl groups, known as “anomalous aryl strengthening”, has
already been observed with bidentate organophosphorous re-
agents such as R2P(O)ÀCH2ÀP(O)R2.[25] It was supposed that re-
placing an R alkyl group by a conjugated group, such as
a phenyl, in the methylene bisphosphine favors electron deloc-
alization through the carbamide functions by enhancing the
donating effect from the lone pair of the nitrogen to the
oxygen atom. Our results represent a striking illustration of the
contribution of an aryl group, which shed light on the influ-
ence of the hard O-amide group in combination with N-donor
atoms on the selection of the metal cation.
AmIII/EuIII selectivity with a dipicoline triazine core is almost
2-fold higher than with a pyridine one (SFAm/Eu over 10 for 2c
and 3c vs. 5 for te-tpyda). The presence of the phenanthroline
moiety also enhances the AmIII/EuIII selectivity (SFAm/Eu =26 and
19 for 1c and 1d, respectively). These interesting separation
factors are comparable to the value of PTA presented by Yaita
(SFAm/Eu =20, 1m HNO3),[26] and confirm the interest of dipicoli-
namide phenanthroline structures for the design of a powerful
GANEX process extractant.
Figure 3. Extraction of AmIII and PuIV by 1d in n-octanol. T=258C; 239Pu and
241Am as traces.
Extraction tests on UVI and NpV–VI
Regarding the potential of 1c and 1d ligands in a new GANEX
extraction process, two complementary experiments were car-
ried out to determine their ability to extract 238UVI and 237NpV–VI
from a 3m nitric acid solution. Data are presented in Table 5.
Results show that 1c and 1d are both able to extract 237Np
and 238UVI with good distribution coefficients (D>2 for urani-
um and >10 for neptunium). Unfortunately, formation of
a third phase was observed during uranium extraction with 1d
due to its poor solubility in n-octanol. However, the ligands
Table 5. Distribution coefficients of NpV–VI and UVI by diamidopolynitro-
gen ligands.[a]
Extractant
1c
1d
2.6
16.6
>2[b]
[HNO3]eq [M]
DNp(V–VI)
DU(VI)
2.6
11
1.9
[a] Extractant: 0.01 molLÀ1 in n-octanol; [237NpV–VI]=6.5ꢂ10À4 molLÀ1 or
238UVI]=4.10À3 molLÀ1; [HNO3]aq.init =3 molLÀ1, 25.08C. [b] 3rd Phase for-
mation: [U]aq,eq =10% [U]ini.
To check the stoichiometry of the extracted complexes, stud-
ies were performed with a representative molecule of the
series, namely 1d. Only the variation in Am and Pu extraction
[
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vent signal as lock. Chemical shifts (d) are given in ppm and cou-
pling constants (J) in Hz with the following abbreviation for signal
multiplicity: s (singlet), d (doublet), dd (doublet of doublets), dt
(doublet of triplets), t (triplet), td (triplet of doublets), q (quartet),
qd (quartet of doublets), quint (quintuplet), st (sextuplet), m (mul-
tiplet), and further qualified as b (broad). HRMS (EI and ESI) were
measured on a MAT95XL Thermofinnigan spectrometer and were
performed at the “Centre Commun de Spectromꢀtrie de Masse”,
Universitꢀ Claude Bernard Lyon 1, France. HRMS (MALDI) were
measured on a MALDI-TOF-TOF (Autoflex III from Bruker) and were
performed at INRA in Nantes.
ability to extract neptunium from a mixture of V and VI oxida-
tion states is of particular interest as both are found in fuel dis-
solution solutions. These results confirm the interest in
dipicolinamide phenanthroline sequences to explore a GANEX-
based process.
Conclusion
In this study, we have reported the synthesis of 12 new bitopic
molecules designed for the GANEX process: 6,6’-(1,10-phenan-
trolin-2,9-diyl)-2,2’-dipicolinamides 1a–1d and 6,6’-(2-substitut-
ed-1,3,5-triazine-4,6-diyl)-2,2’-dipicolinamides 2a–4b. Improved
synthesis pathways were developed to prepare these mole-
cules. Obviously, the developed procedure to reach 4,6-dipico-
linamide 1,3,6-triazines should allow the preparation of
number of trisubstituted 1,3,5-triazine derivatives bearing dif-
ferentiated groups at either the 2-, 4-, and 6 positions.
2,9-Di(6-picolin-2-yl)-1,10-phenanthroline (10): Route I: A mixture
of 2,9-dichloro-1,10-phenanthroline (685 mg, 2.7 mmol), 2-tributyl-
stannyl-6-picoline (4.2 g, 4.0 equiv), [Pd(PPh3)4] (322 mg, 0.1 equiv),
and freshly distilled and degassed toluene (100 mL) was heated at
reflux for 24 h under argon. The solvent was evaporated and the
residue was dissolved in CH2Cl2. The resulting solution was then fil-
tered on Celiteꢃ and successively washed with water, an aqueous
solution of KF, and an aqueous saturated solution of NaHCO3. The
organic phase was dried with Na2SO4, filtered, and the solvent
evaporated. The crude product was then dissolved in a small
amount of CH2Cl2 and the resulting white precipitate was filtered.
The filtrate was evaporated and purified by chromatography on
silica gel (eluent PE (Petroleum Ether)/AcOEt 50:50). The expected
phenanthroline 10 was obtained in 85% yield (850 mg) as a yellow
Four of these lipophilic molecules 1c, 1d, 2c, and 3c were
retained for extraction investigations mostly because of their
good solubility in n-octanol solvent. Unfortunately, trifluoro-
methyl-triazine-based ligands 4a and 4b were rejected for this
purpose due to their sensitive electrophilic behavior in an alco-
hol/water medium.
1
3
powder. M.p. 2238C; H NMR (CDCl3): d=8.96 (d, J=8.4, 2H, H3),
3
3
3
Extraction results show that these new ligands can extract
actinides at different oxidation states from a highly acidic
medium (3m HNO3) with the order of affinity PuIV >AmIII >CmIII
whereas EuIII, representative of lanthanides(III), remains in the
aqueous phase. Introduction of a donor group on the poly-ni-
trogen ring sequence provides a better extraction of PuIV as al-
ready described with amidoterpyridines.[7] The combination of
a rigid pre-organized conformation and an increasing number
of nitrogen-donor atoms presented by the dipicolinamide phe-
nanthroline series leads to a better extraction efficiency in
comparison with known dipyridinyl-triazine- or terpyridine-
based ligands. Furthermore, compound 1d appears the best
candidate for the group separation of actinides from a spent
fuel dissolution solution. The presence of a phenyl group on
amide functions leads to higher performances despite a de-
creasing solubility in the organic phase, which limits its exploi-
tation in the GANEX process. The introduction of lipophilic
chains on the phenanthroline core could thus be proposed to
improve the design of more efficient extractants in this series
and studies are now currently ongoing in our laboratory.
8.91 (d, J=7.8, 2H, H3’), 8.41 (d, J=8.4, 2H, H4), 7.90 (t, J=7.8,
2H, H4’), 7.86 (s, 2H, H5), 7.29 (d, J=7.8, 2H, H5’), 2.73 ppm (s, 6H,
3
2CH3); 13C NMR (CDCl3): d=157.8 (2Cq), 156.1 (2Cq), 155.5 (2Cq),
145.6 (2Cq), 137.2 (2C4’), 137.2 (2C4), 129.0 (2Cq), 126.6 (2C5), 123.8
(2C5’), 120.6 (2C3), 119.2 (2C3’), 24.7 ppm (2CH3); HRMS (EI): m/z
calcd for C24H18N4: 362.1531 [M]+; found: 362.1533. Compound 10
was also obtained by Route II: See the Supporting Information.
6,6’-(1,10-Phenanthrolin-2,9-diyl)-2,2’-dipicolinic acid (13): SeO2
(1.96 g, 8.0 mmol, 8 equiv) was added to a solution of 10 in pyri-
dine (790 mg in 60 mL). After 5 days of heating at reflux, the hot
crude product was filtrated through a pad of Celite that was
washed with methanol. The filtrate was allowed to warm to RT and
a part of solvents were evaporated. Then, dichloromethane was
added and the expected product 13 was isolated by filtration in
98% yield (0.91 g) as a yellow powder. M.p.>2308C; 1H NMR
(DMSO): d=9.21 (dd, 3J=7.6, 4J=0.8 Hz, 2H), 9.00 (d, 3J=8.4 Hz,
3
3
3
2H), 8.72 (d, J=8.4 Hz, 2H), 8.33 (t, J=7.6 Hz, 2H), 8.22 (d, J=
7.6 Hz, 2H), 8.12 ppm (s, 2H, H5); 13C NMR (DMSO): d=166.0 (2CO),
155.4 (2Cq), 154.1 (2Cq), 149.1 (2Cq), 145.0 (2Cq), 139.1 (2C4’), 137.6
(2C4), 129.2 (2Cq), 127.1 (2C5), 125.3 (2C5’), 124.6 (2C3’), 120.5 ppm
(2C3); HRMS (ESI+): m/z calcd for C24H15N4O4 423.1091 [M+H]+;
found: 423.10936
6-Picolinyl-2-carboxamidine (18): 2-Cyano-6-picoline 16 (4.0 g,
34.90 mmol) was added to a solution of NaOMe (36.65 mmol,
1.05 equiv) in MeOH (40 mL). After 3 h at RT, NH4Cl (4.19 g,
76.8 mmol, 2.2 equiv) was added in portions and the mixture was
heated at reflux for 3 h. The NaCl formed was then filtered and the
solvent evaporated. CH2Cl2 was added to the resulting crude prod-
uct and the precipitate was filtered and dried to yield 80% of the
expected carboxamidine 18 (3.76 g) as a white powder. M.p. 858C;
Experimental Section
Synthesis of the ligands
General: Solvents were purified and dried by standard methods
prior to use. n-BuLi (2,5m in hexanes) was purchased from ACROS.
NaH (60% dispersion in mineral oil) was purchased from ALDRICH
and was washed with petroleum ether prior to use. All reactions
were monitored by TLC on commercially available pre-coated
plates (Kieselgel 60 F254) and the products were visualized with
a Mohr solution (10 g of FeSO4 in 100 mL of H2O). Kieselgel 60,
230–400 mesh (Merck) or neutral alumina was used for column
chromatography with compressed air. 1H and 13C NMR spectra
were recorded on a Bruker AC 300 MHz using the deuterated sol-
3
3
1H NMR (DMSO): d=8.07 (d, J=7.8 Hz, 1H, H3), 7.90 (t, J=7.5 Hz,
3
1H, H4), 7.48 (d, J=7.5 Hz, 1H, H5), 2.55 ppm (s, 3H, CH3); 13C NMR
(DMSO): d=160.9 (Cq), 157.6 (Cq), 146.9 (Cq), 137.7 (C4), 126.2 (C5),
119.0 (C3), 23.9 ppm (CH3); HRMS (ESI+): m/z calcd for C7H10N3
136.0869 [M+H]+; found: 136.0867.
2,4-Di(6-picolin-2-yl)-1,3,5-triazapentadiene (19): NaH (1.5 equiv)
was added in portions to a solution of 2-cyano-6-picoline 16
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Full Paper
(344 mg, 2.91 mmol, 1.0 equiv) and carboxamidine 18 (500 mg,
2.91 mmol, 1.0 equiv) in DMSO (6 mL). After stirring overnight at
RT, CH2Cl2 was added and the mixture was washed with water,
dried on Na2SO4, filtered, and the solvent evaporated. The crude
product was purified by chromatography on silica gel (eluent: EP/
AcOEt 80:20). The expected product 19 was obtained with 62%
118.8 (q, CFJ=275.3, CF3), 24.4 ppm (2CH3); 19F NMR (CDCl3): d=
À71.91 ppm (s, CF3); HRMS (MALDI): m/z calcd for C16H12N5F3Na:
354.0937 [M+Na]+; found: 354.0952.
General procedure B: Triazine oxidation with SeO2
1
SeO2 (16 equiv) was added to a solution of triazine 15 in pyridine
(0.05m). After 5 days at 808C, the hot crude product was filtrated
through a pad of Celite that was washed with methanol. The fil-
trate was allowed to warm to RT and a part of solvents were
evaporated. Then, H2O was added and the expected product was
isolated by filtration and drying under vacuum.
yield (456 mg) as a white powder. M.p.1198C; H NMR (CDCl3): d=
3
11.33 (b, 1H, NH), 9.56 (b, 2H, 2NH), 8.36 (d, J=7.8 Hz, 2H, H3),
3
3
7.72 (t, J=7.8 Hz, 2H, H4), 7.23 (d, J=7.8 Hz, 2H, H5), 2.66 ppm (s,
6H, 2CH3); 13C NMR (DMSO): d=165.1 (2Cq), 157.4 (2Cq), 151.5
(2Cq), 137.1 (2C4), 124.7 (2C5), 118.9 (2C3), 24.4 ppm (2CH3); HRMS
(MALDI): m/z calcd for C14H16N5 254.1400 [M+H]+; found:
254.1408.
6,6’-(2-Phenyl-1,3,5-triazine-4,6-diyl)-2,2’-dipicolinic acid (20a):
Compound 20a was obtained by the General Procedure B with tri-
azine 15a (600 mg, 1.8 mmol, 1.0 equiv), pyridine (45 mL), and
SeO2 (3.20 g, 28.3 mmol, 16.0 equiv) in 91% yield (0.62 g) as
a white powder. M.p.>2308C; 1H NMR (DMSO): d=8.93 (m, 2H),
General procedure A (Route V) to compounds 15a–i: Cycli-
zation of 19 with an anhydride
3
4
8.76 (dd, J=8.1, J=1.5 Hz, 2H), 8.32 (m, 4H), 7.73 ppm (m, 3H);
13C NMR (DMSO): d=171.9 (Ph-CqTz), 170.9 (2CO), 166.0 (2Cq),
153.0 (2Cq), 149.2 (2Cq), 138.9 (2C3 or 2C4), 134.9 (Cq-Ph), 133.4
(C4’), 129.1 (2C3’), 128.9 (2C5), 127.8 (2C2’), 127.3 ppm (2C3 or 2C4);
HRMS (MALDI): m/z calcd for C21H13N5O4Na: 422.0860 [M+Na]+;
found: 442.0850.
The anhydride (2.0 equiv) was added in three portions to a vigo-
rously stirred solution of triazapentadiene 19 at 08C in Et2O (0.3m).
After 3 h at RT, the solvent was removed and the residue was dis-
solved in CH2Cl2, washed with NaOH (3m) and water, dried on
Na2SO4, filtered, and the solvent evaporated. The expected triazine
was purified by flash chromatography on silica gel.
6,6’-(2-Trifluoromethyl-1,3,5-triazine-4,6-diyl)-2,2’-dipicolinic acid
(20d): Compound 20d was obtained by the General Procedure B
with triazine 15d (500 mg, 1.5 mmol, 1.0 equiv), pyridine (37 mL),
and SeO2 (2.68 g, 24.2 mmol, 16.0 equiv) with 81% yield (473 mg)
as a whitish powder. M.p.>2308C; 1H NMR (DMSO): d=8.88 (dd,
3J=6.4, 4J=2.4 Hz, 2H), 8.34 ppm (m, 4H); 13C NMR (DMSO): d=
171.8 (2Cq), 165.0 (2Cq), 164.4 (q, CFJ=37.0 Hz, CF3-CqTz), 151.6
(2Cq), 149.6 (2Cq), 139.2 (2C3 or 2C4), 128.1 (2C5), 127.9 (2C3 or 2C4),
119.0 ppm (q, CFJ=275.0 Hz, CF3); 19F NMR (DMSO): d=
À70.66 ppm (s, CF3); HRMS (MALDI): m/z calcd for C16H8N5O4F3Na:
414.0421 [M+Na]+; found: 414.0421.
2-Phenyl-4,6-di(6-picolin-2-yl)-1,3,5-triazine (15a): Compound
15a was obtained by the General Procedure A with triazapenta-
diene derivative 19 (200 mg, 0.73 mmol), benzoic anhydride
(365 mg, 1.58 mmol, 2.0 equiv) in Et2O (3 mL). The crude product
was purified on flash chromatography (eluent: PE/AcOEt 10:90) to
yield 93% of the expected triazine 15a (231 mg) as a white
powder. M.p. 1768C; 1H NMR (CDCl3): d=8.81 (dd, 3J=6.0, 4J=
1.5 Hz, 2H), 8.64 (d, 3J=7.8 Hz, 2H), 7.84 (t, 3J=7.8 Hz, 2H), 7.60
3
(m, 3H), 7.39 (d, J=7.8 Hz, 2H), 2.79 ppm (s, 6H, 2CH3); 13C NMR
(CDCl3): d=172.6 (Ph-CqTz), 171.7 (2Cq), 159.4 (2Cq), 152.8 (2Cq),
137.1 (2C4), 135.5 (Cq-Ph), 132.9 (C4’), 129.3 (2C2’), 128.6 (2C3’), 126.2
(2C5), 122.2 (2C3), 24.6 ppm (2CH3); HRMS (EI): m/z calcd for
C21H17N5: 339.1484 [M]+; found: 339.1485. Compound 15a was
also obtained by Route III (see the Supporting Information).
Procedure C: Triazine oxidation with CrO3
6,6’-(2-Amino-1,3,5-triazine-4,6-diyl)-2,2’-dipicolinic acid (20b):
CrO3 (0.80 g, 8.1 mmol, 6.0 equiv) was added in 0.10 g portions
over 3 h to a solution of amino-triazine 15b (0.35 g, 1.3 mmol) in
concentrated H2SO4 (10 mL) cooled to 08C. After complete addition
of CrO3, the mixture was stirred for 8 h at 0–58C, and 36 h at RT.
The viscous reaction solution was then poured onto ice with stir-
ring. The precipitated product was finally isolated by filtration,
washed with water, and dried under vacuum to yield 61% (0.26 g)
of the triazine 20b as a yellow powder. M.p.>2308C; 1H NMR
(CDCl3): d=8.67 (dd, 3J=6.8, 4J=1.6 Hz, 2H), 8.23 (m, 4H, H3),
8.14 ppm (s, 2H, NH2); 13C NMR (CDCl3): d=170.2 (2Cq), 167.9 (NH2-
CqTz), 166.0 (2CO), 153.6 (2Cq), 148.7 (2Cq), 138.6 (2C3 or 2C4),
126.9 (2C5), 126.7 ppm (2C3 or 2C4); HRMS (MALDI): m/z calcd for
C15H10N6O4Na: 361.0656 [M+Na]+; found: 361.0653.
2-Amino-4,6-di(6-picolin-2-yl)-1,3,5-triazine (15b): NaH was
added in portions (2.5 mmol, 1.0 equiv) to a solution of 2-cyano-6-
methylpyridine 16 (0.60 g, 5.1 mmol, 2.0 equiv) and guanidine hy-
drochloride (350 mg, 3.7 mmol, 1.4 equiv) in freshly distilled EtOH
(10 mL). The mixture was then stirred for 2 h at RT and heated at
reflux for 24 h under an Ar atmosphere. After cooling of the mix-
ture to RT, the expected product was isolated by filtration and
washed with water. The pure triazine 15b was obtained in 77%
yield (0.79 g) as a white powder. M.p.>2308C; 1H NMR (DMSO):
d=8.34 (d, J=7.8 Hz, 2H, H3), 8.13 (s, 2H, NH2), 7.97 (t, J=7.8 Hz,
2H, H4), 7.52 (d, 3J=7.8 Hz, 2H, H5), 2.59 ppm (s, 6H, 2CH3);
13C NMR (DMSO): d=170.1 (2Cq), 167.8 (NH2-CqTz), 158.5 (2Cq),
152.4 (2Cq), 137.9 (2C4), 126.2 (2C5), 121.0 (2C3), 24.0 ppm (2CH3);
HRMS (EI): m/z calcd for C15H14N6 278.1280 [M]+; found: 278.1279.
3
3
For the synthesis of triazine 15c, 15e, 15 f, 15g, 15h, and 15i see
the Supporting Information.
General procedure D: Peptide coupling route to amides
HOBt (0.3 equiv per acid functional group), the corresponding
amine (3 equiv per acid functional group), and EDC (1.05 equiv per
acid functional group) were successively added to a solution of
carboxylic acid in DMF (0.05m). After 48 h at RT, DMF was evapo-
rated and dichloromethane was added. The solution was washed 3
times with water, dried (Na2SO4) and evaporated under reduced
pressure. The expected amide was purified by flash chromatogra-
phy on silica gel.
2-Trifluoromethyl-4,6-di(6-picolin-2-yl)-1,3,5-triazine (15d): Com-
pound 15d was obtained by the General Procedure A with triaza-
pentadiene derivative 19 (700 mg, 2.8 mmol), trifluoroacetic anhy-
dride (1.1 g, 0.78 mL, 2 equiv) in Et2O (5 mL). The crude product
was purified on flash chromatography (eluent: PE/AcOEt 20:80) to
yield 86% of the expected triazine 15d (800 mg) as a whitish
3
powder. M.p. 1748C; 1H NMR (CDCl3): d=8.56 (d, J=7.6 Hz, 2H),
3
3
7.83 (t, J=7.6 Hz, 2H), 7.42 (d, J=7.6 Hz, 2H), 2.77 ppm (s, 6H,
CH3); 13C NMR (CDCl3): d=173.0 (2Cq), 166.8 (q, CFJ=38.2, CF3-
CqTz), 160.0 (2Cq), 151.0 (2Cq), 137.4 (2C4), 127.3 (2C5), 123.0 (2C3),
6,6’-(2-Amino-1,3,5-triazin-4,6-diyl)-2,2’-di(N,N-diethyl)picolina-
mide (2a): Compound 2a was obtained by the general procedure
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D with acid 20 (500 mg, 1.5 mmol, 1.0 equiv), EDC (609 mg,
3.1 mmol, 2.1 equiv), HOBt (139 mg, 0.9 mmol, 0.6 equiv), N,N-di-
ethylamine (458 mL, 4.4 mmol, 6.0 equiv) in dry DMF (40 mL). The
crude product was purified by chromatography on silica gel
(eluent: AcOEt/MeOH 95:5). The expected product 2a was ob-
6,6’-(1,10-Phenanthrolin-2,9-diyl)-2,2’-di(N,N-diethyl)picolina-
mide (1a): Compound 1a was obtained by the General Procedure
E with acid 13 (298 mg, 0.7 mmol, 1.0 equiv), SOCl2 (6.0 mL), CH2Cl2
(8.0 mL), Et3N (594 mL, 4.26 mmol, 6.0 equiv), and N,N-dietylamine
(220 mL, 2.1 mmol, 3.0 equiv). The crude product was purified by
chromatography on silica gel (eluent: PE/AcOEt, 20:80). The ex-
pected product 1a was obtained pure with 52% yield (210 mg) as
a whitish powder. M.p. 2018C; 1H NMR (CDCl3): d=9.11 (dd, 3J=
7.8,4J=0.6 Hz, 2H, H3’), 8.88 (d, 3J=8.4 Hz, 2H, H3), 8.42 (d, 3J=
8.4 Hz, 2H, H4), 8.10 (t, 3J=7.8 Hz, 2H, H4’), 7.89 (s, 2H, H5), 7.72
1
tained pure with 59% yield (392 mg). M.p. 1968C; H NMR (CDCl3):
3
3
d=8.65 (dd, J=7.6,4J=0.8 Hz, 2H, H3), 7.97 (t, J=7.6 Hz, 2H, H4),
3
4
3
7.76 (dd, J=7.6, J=0.8 Hz, 2H, H5), 7.35 (m, 2H, NH2), 3.62 (q, J=
7.2 Hz, 4H, 2CH2), 3.46 (q, J=7.2 Hz, 4H, 2CH2), 1.33 (t, J=7.2 Hz,
6H, 2CH3), 1.30 ppm (t, J=7.2 Hz, 6H, 2CH3); 13C NMR (CDCl3): d=
3
3
3
3
4
3
170.9 (2Cq), 168.2 (2CO and NH2-CqTz), 154.9 (2Cq), 152.8 (2Cq),
137.6 (2C4), 125.1 (2C3), 124.9 (2C5), 43.6 (2CH2), 40.5 (2CH2), 14.4
(2CH3), 12.9 ppm (2CH3); HRMS (EI): m/z calcd for C23H28N8O2:
448.2335 [M]+; found: 448.2336.
(dd, J=7.8, J=0.6 Hz, 2H, H5’), 3.65 (q, J=6.9 Hz, 4H, 2CH2), 3.47
3
3
(q, J=6.9 Hz, 4H, 2CH2),1.34 (t, J=6.9 Hz, 6H, 2CH3), 1.27 ppm (t,
3J=6.9 Hz, 6H, 2CH3); 13C NMR (CDCl3): d=168.2 (2CO), 155.1
(2Cq), 154.2 (2Cq), 154.1 (2Cq), 145.0 (2Cq), 137.6 (2C4’), 136.9 (2C4),
128.8 (2Cq), 126.5 (2C5), 123.3 (2C5’), 122.2 (2C3’), 120.5 (2C3), 42.9
(2CH2), 39.9 (2CH2), 14.1 (2CH3), 12.5 ppm (2CH3); HRMS (EI): m/z
calcd for C32H32N6O2 532.2587 [M]+; found: 532.2587.
6,6’-(2-Amino-1,3,5-triazin-4,6-diyl)-2,2’-di(N-ethyl-N-phenyl)pico-
linamide (2b): Compound 2b was obtained by the General Proce-
dure D with acid 20b (350 mg, 1.0 mmol, 1.0 equiv), EDC (425 mg,
2.2 mmol, 2.1 equiv), HOBt (100 mg, 0.6 mmol, 0.6 equiv), N-ethyl-
aniline (389 mL, 3.1 mmol, 6.0 equiv) in dry DMF (30 mL). The crude
product was purified by chromatography on silica gel (eluent:
AcOEt/MeOH 95:5). The expected product 2b was obtained with
54% yield (248 mg) as a white powder. M.p.>2308C; 1H NMR
(CDCl3): d=8.44 (b, 2H, H5), 8.11 (b, 2H, NH2), 7.70 (b, 2H, H4), 7.43
(b, 2H, H3), 7.17 (b, 8H, HPhenyl), 7.09 (b, 2H, HPhenyl), 4.09 (q, 3J=
7.2 Hz, 4H, 2CH2), 1.30 (t, 3J=7.2, 6H, 2CH3); 13C NMR (CDCl3): d
=170.5 (2Cq), 168.2 (NH2-Cq), 168.1 (2CO), 154.2 (2Cq), 153.2 (2Cq),
142.5 (2Cq), 136.6 (2C4), 129.0 (4CPhenyl), 128.1 (4CPhenyl), 126.9
(2CPhenyl), 125.6 (2C3), 124.7 (2C5), 45.2 (2CH2), 12.9 ppm (2CH3);
HRMS (ESI+): m/z calcd for C31H28N8O2Na: 567.2233 [M+Na]+;
found: 567.2232.
6,6’-(1,10-Phenanthrolin-2,9-diyl)-2,2’-di(N-ethyl-N-phenyl)picoli-
namide (1b): Compound 1b was obtained by the General Proce-
dure E with acid 13 (500 mg, 1.2 mmol, 1.0 equiv), SOCl2 (10.0 mL),
CH2Cl2 (12.0 mL), Et3N (991 mL, 7.1 mmol, 6.0 equiv), and N-ethylani-
line (447 mL, 3.5 mmol, 3.0 equiv). The crude product was purified
by chromatography on silica gel (eluent: PE/AcOEt 40:60). The ex-
pected product 1b was obtained pure in 31% yield (230 mg) as
a whitish powder. M.p.>2308C; 1H NMR (CDCl3): d=8.90 (d, 3J=
7.8 Hz, 2H, H3’), 8.35 (m, 4H, H3, H4), 7.95 (t, 3J=7.8 Hz, 2H, H4’),
3
7.86 (s, 2H, H5), 7.77 (d, J=7.8 Hz, 2H, H5’), 7.16 (m, 8H, HPhenyl),
3
3
7.03 (m, 2H, HPhenyl), 4.11 (q, J=7.2 Hz, 4H, CH2), 1.31 ppm (t, J=
7.2 Hz, 6H, CH3); 13C NMR (CDCl3): d=167.8 (2CO), 155.2 (2Cq),
154.2 (2Cq), 153.1 (2Cq), 145.2 (2Cq), 143.4 (2Cq), 137.4 (2C4’), 136.6
(2C3 or 2 C4), 129.0 (2Cq), 128.8 (4CPhenyl), 127.7 (4CPhenyl), 126.6 (2C5),
126.5 (2CPhenyl), 124.6 (2C5’), 122.3 (2C3’), 120.8 (2C3 or 2C4), 45.5
(2CH2), 12.8 ppm (2CH3); HRMS (EI): m/z calcd for C40H32N6O2
628.2587 [M]+; found: 628.2587.
6,6’-(2-Amino-1,3,5-triazin-4,6-diyl)-2,2’-di(N,N-dioctyl)picolina-
mide (2c): Compound 2c was obtained by the General Procedure
D with acid 20b (500 mg, 1.5 mmol, 1.0 equiv), EDC (608 mg,
2.2 mmol, 2.1 equiv), HOBt (139 mg, 0.6 mmol, 0.6 equiv), and N,N-
dioctylamine (1.34 mL, 3.1 mmol, 6.0 equiv) in dry DMF (16 mL).
The crude product was purified by chromatography on silica gel
(eluent: PE/AcOEt 60:40). The expected product 2c was obtained
6,6’-(1,10-Phenanthrolin-2,9-diyl)-2,2’-di(N,N-dioctyl)picolinamide
(1c): Compound 1c was obtained by the General Procedure E with
acid 13 (395 mg, 0.9 mmol, 1.0 equiv), SOCl2 (8.0 mL), CH2Cl2
(10.0 mL), Et3N (784 mL, 5.6 mmol, 6.0 equiv), and N,N-dioctylamine
(1.06 mL, 2.8 mmol, 3.0 equiv). The crude product was purified by
chromatography on silica gel (eluent: PE/AcOEt 40:60). The expect-
ed product 1c was obtained pure with 58% yield (475 mg) as
1
pure with 10% yield (118 mg) as a yellow oil. H NMR (CDCl3): d=
3
4
3
8.67 (dd, J=7.8, J=0.9 Hz, 2H), 7.96 (t, J=7.8 Hz, 2H), 7.75 (dd,
3J=7.8, J=0.9 Hz, 2H), 6.95 (b, 2H, NH2), 3.52 (m, 4H, 2CH2), 3.41
4
(m, 4H, 2CH2), 1.71 (m, 8H, 4CH2), 1.31 (m, 20H, 10CH2), 1.09 (m,
3
3
3
a yellow oil. 1H NMR (CDCl3): d=9.12 (d, J=7.8 Hz, 2H), 8.84 (d,
20H, 10CH2), 0.87 (t, J=6.9 Hz, 6H, 2CH3), 0.77 ppm (t, J=6.9 Hz,
6H, 2CH3); 13C NMR (CDCl3): d=170.9 (2Cq), 168.4 (2CO), 168.2
(NH2-CqTz), 155.2 (2Cq), 152.7 (2Cq), 137.6 (2C4), 125.3 (2C3), 124.9
(2C5), 49.2 (2CH2), 46.4 (2CH2), 31.8 (2CH2), 31.7 (2CH2), 29.7 (2CH2),
29.4 (2CH2), 29.3 (2CH2), 29.1 (2CH2), 28.9 (2CH2), 27.6 (2CH2), 27.3
(2CH2), 26.8 (2CH2), 22.6 (2CH2), 22.5 (2CH2), 14.1 (2CH3), 14.0 ppm
(2CH3); HRMS (MALDI): m/z calcd for C47H76N8O2Na: 807.5983 [M+
Na]+; found: 807.5960.
3J=8.4 Hz, 2H), 8.38 (d, 3J=8.4 Hz, 2H), 8.08 (t, 3J=7.8 Hz, 2H),
3
3
7.87 (s, 2H), 7.69 (d, J=7.8 Hz, 2H), 3.56 (q, J=7.8 Hz, 4H, 2CH2),
3.38 (q, 3J=7.8 Hz, 4H, 2CH2), 1.73 (m, 8H, 4CH2), 1.37 (m, 20H,
3
10CH2), 1.27 (m, 20H, 10CH2), 1.09 (t, J=6.9, 6H, 2CH3), 0.74 ppm
3
(t, J=6.9, 6H, 2CH3); 13C NMR (CDCl3): d=168.8 (2CO), 155.6 (2Cq),
154.7 (2Cq), 154.6 (2Cq), 145.6 (2Cq), 137.9 (2C4’), 137.0 (2C4), 129.2
(2Cq), 126.8 (2C5), 123.7 (2C5’), 122.4 (2C3’), 120.8 (2C3), 49.1 (2CH2),
46.0 (2CH2), 31.8 (2CH2), 31.6 (2CH2), 29.4 (2CH2), 29.3 (2CH2), 29.2
(4CH2), 29.1 (2CH2), 27.6 (2CH2), 27.1 (2CH2), 26.7 (2CH2), 22.6
(2CH2), 22.5 (2CH2), 14.1 (2CH3), 13.9 ppm (2CH3); HRMS (MALDI):
m/z calcd for C56H80N6O2Na: 891.6235 [M+Na]+; found: 891.6237.
General procedure E: Acid chloride route to amides
Carboxylic acid was dissolved in SOCl2 and the mixture was heated
at 908C for 2 h. SOCl2 was eliminated by evaporation and the ob-
tained acid chloride was dissolved in freshly distilled dichlorome-
thane. After cooling at 08C, triethylamine (1.5 equiv per acid func-
tional group) and the corresponding amine (3 equiv per acid func-
tional group) were successively added and the mixture was stirred
at RT until total consumption of the corresponding acid chloride as
monitored by TLC. The mixture was diluted in dichloromethane,
washed with water, dried (Na2SO4), filtered and evaporated under
reduced pressure. The expected amide was purified by flash chro-
matography on silica gel.
6,6’-(1,10-Phenanthrolin-2,9-diyl)-2,2’-di(N-hexyl-N-phenyl)picoli-
namide (1d): Compound 1d was obtained by the General Proce-
dure E with acid 13 (500 mg, 1.2 mmol, 1.0 equiv), SOCl2 (10.0 mL),
CH2Cl2 (12.0 mL), Et3N (719 mg, 7.1 mmol, 6.0 equiv), and N-hexyla-
niline (642 mg, 3.5 mmol, 3.0 equiv). The crude product was puri-
fied by chromatography on silica gel (eluent: CH2Cl2/MeOH 98:2).
The expected product 1d was obtained pure with 58% yield
(508 mg) as a whitish powder. M.p. 1688C; 1H NMR (CDCl3): d=
3
8.85 (d, J=7.2 ppm, 2H), 8.20 (m, 4H, H3), 7.91 (m, 2H), 7.79 (s,
3
2H), 7.75 (d, J=7.2 ppm, 2H), 7.15 (m, 8H, HPhenyl), 7.01 (m, 2H,
Chem. Eur. J. 2014, 20, 7819 – 7829
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HPhenyl), 4.01 (m, 4H, 2CH2), 1.70 (m, 4H, 2CH2), 1.31 (m, 12H, 6CH2),
0.88 ppm (m, 6H, 2CH3); 13C NMR (CDCl3): d=168.0 (2CO), 155.1
(2Cq), 154.0 (2Cq), 153.2 (2Cq), 145.1 (2Cq), 143.6 (2Cq), 137.4
(2C4’), 136.7 (2C3 or 2C4), 129.0 (2Cq), 128.7 (4CPhenyl), 127.6 (4CPhenyl),
126.6 (2C5), 126.4 (2CPhenyl), 124.6 (2C5’), 122.2 (2C3’), 120.8 (2C3 or
2C4), 50.5 (2CH2), 31.5 (2CH2), 27.5 (2CH2), 26.6 (2CH2), 22.5 (2CH2),
14.0 ppm (2CH3); HRMS (MALDI): m/z calcd for C48H48N6O2Na:
763.3731 [M+Na]+; found: 763.3727.
(11.0 mL), CH2Cl2 (15.0 mL), Et3N (853 mL, 6.1 mmol, 6.0 equiv), and
diethylamine (317 mL, 3.1 mmol, 3.0 equiv). The crude product was
purified by chromatography on silica gel (eluent: PE/AcOEt 30:70).
The expected product 4a was obtained with 58% yield (290 mg)
as a whitish powder. M.p. 1658C; H NMR (CDCl3): d=8.78 (dd, J=
7.8, 4J=1.8 Hz, 2H, H3), 8.04 (m, 4H, H4, H5), 3.57 (m, 8H, 4CH2),
1.46 (t, 3J=7.2 Hz, 6H, 2CH3), 1.31 ppm (t, 3J=7.2 Hz, 6H, 2CH3);
13C NMR (CDCl3): d=172.7 (2Cq), 167.1 (2CO), 166.3 (q, CFJ=
38.4 Hz, CF3-CqTz), 155.5 (2Cq), 149.9 (2Cq), 138.2 (2C4), 127.8 (2C5),
126.0 (2C3), 118.9 (q, CFJ=276.5 Hz, CF3), 44.0 (2CH2), 41.1 (2CH2),
14.3 (2CH3), 12.7 ppm (2CH3); 19F NMR (CDCl3): d=À72.04 ppm (s,
CF3); HRMS (MALDI): m/z calcd for C24H27F3N7O2: 502.2173 [M+H]+;
found: 502.2175.
1
3
6,6’-(2-Phenyl-1,3,5-triazin-4,6-diyl)-2,2’-di(N,N-diethyl)picolina-
mide (3a): Compound 3a was obtained by the General Procedure
E with acid 20a (540 mg, 1.4 mmol, 1.0 equiv), SOCl2 (15.0 mL),
CH2Cl2 (17.0 mL), Et3N (1.14 mL, 8.2 mmol, 6.0 equiv) and diethyla-
mine (423 mL, 4.1 mmol, 3.0 equiv). The crude product was purified
by chromatography on silica gel (eluent: PE/AcOEt 30:70). The ex-
pected product 3a was obtained pure with 44% yield (308 mg) as
6,6’-(2-Trifluoromethyl-1,3,5-triazin-4,6-diyl)-2,2’-di(N-ethyl-N-
phenyl)picolinamide (4b): Compound 4b was obtained by the
General Procedure E with acid 20d (500 mg, 1.0 mmol, 1.0 equiv),
SOCl2 (14.0 mL), CH2Cl2 (20.0 mL), Et3N (1.07 mL, 7.7 mmol,
6.0 equiv), and N-ethylaniline (492 mL, 3.8 mmol, 3.0 equiv). The
crude product was purified by chromatography on silica gel
(eluent: PE/AcOEt 50:50). The expected product 4b was obtained
1
a white powder. M.p. 1948C; H NMR (CDCl3): d=8.80 (m, 4H, H3,
3
3
4
H2’), 8.05 (t, J=7.8 Hz, 2H, H4), 7.96 (dd, J=7.8 Hz, J=0.8 Hz, 2H,
3
3
H5), 7.61 (m, 3H, H3’, H4’), 3.62 (q, J=7.2 Hz, 8H, 4CH2), 1.33 (t, J=
7.2 Hz, 6H, 2CH3), 1.49 ppm (t, 3J=7.2 Hz, 6H, 2CH3); 13C NMR
(CDCl3): d=173.1 (Ph-CqTz), 171.4 (2Cq), 167.7 (2CO), 155.3 (2Cq),
152.0 (2Cq), 137.9 (2C4), 135.6 (Cq-Ph), 133.0 (C4’), 129.3 (2C2’), 128.7
(2C3’), 126.6 (2C5), 125.4 (2C3), 43.8 (2CH2), 41.0 (2CH2), 14.7 (2CH3),
12.9 ppm (2CH3); HRMS (EI): m/z calcd for C29H31N7O2: 509.2539
[M]+; found: 509.2536.
1
with 71% yield (540 mg) as a whitish powder. M.p. 1788C; H NMR
(CDCl3): d=8.54 (b, 2H, H3), 7.89 (b, 4H, H1, H2), 7.16 (b, 8H, H4, H5),
6.98 (m, 2H, H6), 4.05 (q, 3J=6.9 Hz, 4H, 2CH2), 1.29 ppm (t, 3J=
6.9 Hz, 6H, 2CH3); 13C NMR (CDCl3): d=172.0 (2Cq), 167.2 (2CO),
165.8 (q, CFJ=38.6 Hz, CF3-CqTz), 155.1 (2Cq), 149.9 (2Cq), 142.5
(2Cq), 137.6 (2C2), 129.2 (4C4 or 4C5), 128.7 (4C4 or 4C5), 128.2 (2C1),
127.4 (2C6), 126.7 (2H3), 119.1 (q, CFJ=264.8 Hz, CF3), 45.3 (2CH2),
12.7 ppm (2CH3); 19F NMR (CDCl3): d=À71.69 ppm (s, CF3); HRMS
(MALDI): m/z calcd for C32H26F3N7O2Na: 620.1992 [M+Na]+; found:
620.1995.
6,6’-(2-Phenyl-1,3,5-triazin-4,6-diyl)-2,2’-di(N-ethyl-N-phenyl)pi-
colinamide (3b): Compound 3b was obtained by the General Pro-
cedure E with acid 20a (500 mg, 1.2 mmol, 1.0 equiv), SOCl2
(14.0 mL), CH2Cl2 (16.0 mL), Et3N (1.05 mL, 7.5 mmol, 6.0 equiv), and
N-ethylaniline (482 mL, 3.7 mmol, 3.0 equiv). The crude product was
purified by chromatography on silica gel (eluent: PE/AcOEt, 20:80).
The expected product 3b was obtained pure with 59% yield
1
(450 mg) as a white powder. M.p. 2048C; H NMR (CDCl3): d=8.75
3
Solvent-extraction tests
(d, J=7.2 Hz, 2H, H2’), 8.58 (b, 2H, H3), 7.89 (b, 2H, H4), 7.80 (b,
2H, H5), 7.64 (m, 3H, H3’, H4’), 7.17 (b, 8H, HPhenyl), 6.99 (b, 2H,
H
Chemical and solutions: n-Octanol was purchased from Aldrich.
Depleted uranyl nitrate from Prolabo, purity 99.9%, was used with-
out further purification. 239–240PuIV solution was purified by fixation
on a DOWEX anion exchange resin at 7m HNO3 and elution with
0.5m HNO3. 237NpV stock solution was prepared from a 237NpV–VI
mixture solution by treating with NaNO2. NpV was then precipitat-
ed by the addition of sodium hydroxide. The NpO2OH, xH2O green
solid was then washed with water, dried and dissolved in 1m HCl.
241AmIII stock solution was obtained by dissolution of AmO2 in
HNO3 followed by AmIII purification on a DOWEX-50 cation ex-
change resin. Am3+ in 0.1m HNO3 was sorbed on the resin,
washed several times with 0.1m HNO3 and eluted with 5m HNO3.
Americium hydroxide was then precipitated by adding sodium hy-
droxide, washed and redissolved in 1m HNO3. 244CmIII stock solu-
tion was obtained from the raffinate of the Am/Cm separation pro-
cess performed in Atalante facility in 2002.[27] 152Eu was purchased
from CERCA-LEA and used without further purification. All these ra-
dioactive solutions were manipulated in gloveboxes.
Phenyl), 4.08 (q, 3J=7.2 Hz, 4H, 2CH2), 1.30 ppm (b, 6H, 2CH3);
13C NMR (CDCl3): d=172.8 (Ph-CqTz), 170.7 (2Cq), 167.8 (2CO),
154.9 (2Cq), 152.0 (2Cq), 142.7 (2Cq), 137.2 (2C4), 135.5 (Cq-Ph),
133.0 (C4’), 129.4 (2C2’), 128.8 (4CPhenyl), 128.5 (4CPhenyl), 128.1 (2C3’),
126.7 (2CPhenyl), 126.5 (2C5), 125.0 (2C3), 45.2 (2CH2), 12.8 ppm
(2CH3); HRMS (EI): m/z calcd for C37H31N7O2 605.2539 [M]+; found:
605.2539.
6,6’-(2-Phenyl-1,3,5-triazin-4,6-diyl)-2,2’-di(N,N-dioctyl)picolina-
mide (3c): Compound 3c was obtained by the General Procedure
E with acid 20a (200 mg, 0.5 mmol, 1.0 equiv), SOCl2 (6.0 mL),
CH2Cl2 (10.0 mL), Et3N (418 mL, 3.0 mmol, 6.0 equiv), and N,N-dio-
ctylamine (452 mL, 1.5 mmol, 3.0 equiv). The crude product was pu-
rified by chromatography on silica gel (eluent: PE/AcOEt 30:70).
The expected product 3c was obtained pure with 56% yield
1
(236 mg) as a yellow oil. H NMR (CDCl3): d=8.80 (m, 4H, H3 and
H2’), 8.03 (t, 3J=7.8 Hz, 2H, H4), 7.92 (dd, 3J=7.8, 4J=0.9 Hz, 2H,
H5), 7.60 (m, 3H, H3’, H4’), 3.60 (m, 8H, 4CH2), 1.78 (m, 8H, 4CH2),
3
1.32 (m, 20H, 10CH2), 1.06 (m, 20H, 10CH2), 0.88 (t, J=6.9 Hz, 6H,
General procedures: Aqueous solutions of nitric acid ([HNO3]=
3m), spiked with radionuclides were contacted for 60 min by
means of an automatic vortex shaker with organic solutions (Vaq =
Vorg), containing the ligand diluted in n-octanol. Aqueous and or-
ganic solutions were mixed in Nalgene tubes thermostated at
258C. After the phase separation by centrifugation and dilution,
500 mL samples of both diluted phases were analyzed using
a gamma-counting spectrometer (HPGe detector, CANBERRA) to
measure activities of 241Am and 152Eu. Activities of 239+240Pu, 237Np,
241Am, and 244Cm were measured using an alpha counting spec-
trometer (silicon detector, CANBERRA). Samples for alpha analysis
were prepared by calcinations of 10 mL of the solution on a stain-
2CH3), 0.72 ppm (t, 3J=6.9 Hz, 6H, 2CH3); 13C NMR (CDCl3): d=
173.1 (Ph-CqTz), 171.2 (2Cq), 167.8 (2CO), 155.5 (2Cq), 151.8 (2Cq),
137.9 (2C4), 135.5 (Cq-Ph), 133.1 (C4’), 129.4 (2C2’), 128.7 (2C3’), 126.6
(2C5), 125.3 (2C3), 49.3 (2CH2), 46.8 (2CH2), 31.8 (2CH2), 31.6 (2CH2),
29.5 (2CH2), 29.3 (2CH2), 29.1 (4CH2), 29.0 (2CH2), 27.6 (2CH2), 27.3
(2CH2), 26.8 (2CH2), 22.6 (2CH2), 22.4 (2CH2), 14.1 (2CH3), 14.0 ppm
(2CH3); HRMS (MALDI): m/z calcd for C53H79N7NaO2: 868.6187 [M+
Na]+; found: 868.6195.
6,6’-(2-Trifluoromethyl-1,3,5-triazin-4,6-diyl)-2,2’-di(N,N-diethyl)-
picolinamide (4a): Compound 4a was obtained by the General
Procedure E with acid 20d (400 mg, 1.0 mmol, 1.0 equiv), SOCl2
Chem. Eur. J. 2014, 20, 7819 – 7829
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ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

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[10] Z. Kolarik, Chem. Rev. 2008, 108, 4208–4252.
less steel disk and carried out in triplicate to reduce uncertainties
in these measurements. 238UVI concentration was analyzed by X-ray
fluorescence (METOREX International) in aqueous phases only,
using 241Am as a source for X-rays. For all samples, the analysis was
repeated three times. The concentration of nitric acid in the aque-
ous phase at equilibrium ([HNO3]eq) was determined by automatic
titration with NaOH 0.1m. The distribution ratio DM for a metallic
cation M is defined as the ratio of the concentration of the metallic
species in the organic phase at equilibrium over its concentration
in the aqueous phase at equilibrium. The separation factor SFM1/M2
for two metallic cations M1 and M2 is defined as the ratio of their
distribution ratios.
Extraction of 239+240PuIV, 241Am, 244Cm and 152Eu: An aqueous
stock solution was spiked with trace amounts of 239+240PuIV, 241Am,
244Cm and 152Eu ([cations]<10À4 molLÀ1). The aqueous and the or-
ganic solution (750 mL) were contacted and were then analyzed
without dilution.
Extraction of 238UVI: The uranium stock solution was prepared by
dissolution of uranium nitrate in nitric acid ([UO22+]=
4.5.10À3 molLÀ1). The aqueous and the organic solutions ([L]=
0.01 molLÀ1) were contacted (950 mL). The aqueous phase was di-
luted 10 times in HNO3 1m and the organic phase 10 times in
a suitable organic media before analysis. HRMS (MALDI): m/z calcd
for C32H26F3N7O2Na: 620.1992; found: 620.199.
[11] P. J. Panak, A. Geist, Chem. Rev. 2013, 113, 1199–1236.
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Iveson, C. Madic, M. L. Russell, T. G. A. Youngs, J. Chem. Soc. Dalton
Trans. 2002, 55–62.
[13] M. Yamada, Y. Nakamura, S. Kuroda, I. Shimao, Bull. Chem. Soc. Jpn.
1990, 63, 2710–2712.
[14] a) R. F. Zong, R. P. Thummel, J. Am. Chem. Soc. 2004, 126, 10800–10801;
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Extraction of 237NpV–VI 237Np stock solution was prepared from an
:
0.1 molLÀ1 in 1m HCl stock solution by a 170 times dilution in
HNO3 3m ([Np]=5.8.10À4 molLÀ1). The aqueous and the organic
solutions (300 mL; [L]=0.01 molLÀ1) were contacted and then ana-
lyzed by alpha spectrometry without further dilution.
Keywords: actinides · lanthanides · ligands · heterocycles ·
synthetic methods
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Received: February 20, 2014
Chem. Eur. J. 2014, 20, 7819 – 7829
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