CMP(O) tripodands: Synthesis, potentiometric studies and extractions

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CMP(O) tripodands: synthesis, potentiometric studies and extractions

a

´

Marta M. Reinoso-Garcıa, Dominik Janczewski, David N. Reinhoudt,

Willem Verboom,*^aEl(bieta Malinowska,^bMariusz Pietrzak,^bClement Hill,^c

Jirı Baca, Bohumır Gruner, Pavel Selucky and Cordula Gruttner

´ ´ ¨ ¨

´

d

e

f

Received (in Montpellier, France) 11th January 2006, Accepted 23rd February 2006

First published as an Advance Article on the web 21st March 2006

DOI: 10.1039/b600412a

Ligand systems containing three carbamoylmethylphosphonate (CMP) or -phosphine oxide

(CMPO) moieties attached to a tripodal platform have been synthesized for metal complexation

and subsequent extraction from HNO₃solutions. The incorporation into ion selective electrodes

(ISE) and picrate extractions with Na⁺, K⁺, Ag⁺, Ca²⁺, Cd²⁺, Hg²⁺, Pb²⁺, Cu²⁺, Eu³⁺and

Fe³⁺shows that CMPO tripodand 3 is very selective for Eu³⁺and forms a very stable complex

(log b_ML= 28.3). Liquid–liquid extractions performed with Eu³⁺and Am³⁺show reasonable

extraction properties of the CMP(O) tripodands 3, 11 and 13 in 1,1,2,2-tetrachloroethane, while

in 1-octanol for all tripodands studied the distribution coeﬃcients are low. Upon addition of the

synergistic agent hexabrominated cobalt bis(dicarbollide) anion (bromo-COSAN) the distribution

coeﬃcients for Am³⁺and Eu³⁺extraction increase considerably for CMP(O) tripodands 3 and 4.

Covalently linked COSAN only enhances the extraction of Am³⁺and Eu³⁺at 0.001–0.01 M

HNO₃. The functionalization of dendrimer coated magnetic silica particles with CMP(O)

tripodands led to very eﬀective particles (31 and 32) for Am³⁺and Eu³⁺removal from 0.01 M

HNO₃solutions.

Introduction

Results and discussion

Carbamoylmethylphosphonate (CMP) and -phosphine oxide

(CMPO) ligands are well known for the extraction of Am³⁺

and Eu³⁺from nuclear waste.¹Their attachment to molecular

platforms as calixarenes^2–4and cavitands⁵led to high extrac-

tion eﬃciencies and selectivities. In most cases these platforms

contain four ligating sites. However, only three CMPO moi-

eties are necessary for the coordination of a metal ion. To the

best of our knowledge, there is only one example of a tripodal

platform, viz. a trityl skeleton, with CMPO moieties,⁶while in

general the number of tripodal ligands for actinide and/or

lanthanide complexation is limited.⁷

Synthesis

The synthesis of the tripodal CMP(O) compounds is depicted

in Scheme 1. The ligating sites are introduced on the tripodal

scaﬀold via two steps starting from 1,1,1-tris[(aminopropoxy)

methyl]propane (1), the synthesis of which has been described

previously.⁸Acylation of amine 1 with chloroacetyl chloride

and Et₃N as a base in CH₂Cl₂aﬀorded 1,1,1-tris[(chloro-

acetamidopropoxy)methyl]propane (2) in 54% yield. Arbusov

reaction of

2 with ethyl diphenylphosphinite gave tris

[(diphenylcarbamoyl)methylphosphine oxide N-propoxy)-

methyl]propane (3) (CMPO tripodand) as a brown solid in

83% yield. Tris[(diethylcarbamoylmethylphosphonate N-pro-

poxy)methyl]propane (4) (CMP tripodand) was obtained in

89% yield via an Arbusov reaction with triethyl phosphite.

The ¹H NMR spectra of CMPO tripodand 3 and CMP

tripodand 4 exhibit characteristic signals for the CMP(O)

methylene hydrogens at 3.40 ppm (²J_PH= 13.2 Hz) and

2.85 ppm (²J_PH= 20.8 Hz), respectively.

Recently, we reported the synthesis, extraction and sensing

behaviour of trimethylolpropane-based tripodal ionophores

with picolin(thio)amide and N-acyl(thio)urea ligating

sites.⁸This paper mainly deals with the behavior of the

corresponding CMP(O) derivatives 3 and 4 and some deriva-

tives thereof. In addition, the use of CMP(O) tripodands on

magnetic silica particles is studied in magnetically assisted

chemical separation.

In order to introduce an extra functionality, which can be

used as a handle for the coupling to COSAN moieties or mag-

netic silica particles, carbamate 5 was prepared following a

literature procedure, starting from the commercially available

1,1,1-tris(hydroxymethyl)aminomethane.⁹For the introduc-

tion of the CMP(O) moieties the same strategy as for CMP(O)

tripodands 3 and 4 was followed. Acylation of carbamate 5

followed by an Arbusov reaction gave 7 and 8 in 94 and 60%

yield, respectively. The terminal amino group, which was

protected by the Cbz (benzyloxycarbonyl) group, was depro-

tected by catalytic hydrogenation aﬀording the target com-

pounds 9 and 10 in 87 and 85% yield, respectively (Scheme 2).

^aLaboratory of Supramolecular Chemistry and Technology, Mesa⁺

Research Institute for Nanotechnology, University of Twente, P. O.

Box 217, 7500 AE Enschede, The Netherlands. E-mail:

w.verboom@utwente.nl

^bDepartment of Analytical Chemistry, Faculty of Chemistry, Warsaw

University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland

c

`

Commissariat al’ Energie Atomique, CEA-Valrho, DRCP/SCPS/

LCSE, baˆt. 399, BP 17171, 30207 Bagnols-sur-Ceze, France

`

^dInstitute of Inorganic Chemistry, Academy of Sciences of the Czech

ˇ

Republic, 250 68 Husinec-Rezꢀ near Prague, Czech Republic

^eNuclear Research Institute REZ, CZ-250 68 Rez, Czech Republic

^fMicromod Partikeltechnologie GmbH, D-18119 Rostock, Germany

ꢀc

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Scheme 1

¹H NMR spectroscopy conﬁrmed the formation of 9 and 10

by the absence of the signal at B5.3 ppm of the CH₂of the

Cbz groups in 7 and 8, and the presence of aromatic signals for

CMPO tripodand 9 and ethoxy signals of CMP tripodand 10.

In order to increase the solubility of compounds 3 and 4,

especially CMP tripodand 4, long alkyl chains were attached

via the terminal amino group of CMP(O) tripodands 9 and 10

(Scheme 3). The terminal amino group is at a sterically

hindered position, which inﬂuences its reactivity. A nine

carbon chain was introduced via an acylation reaction with

nonanoyl chloride to give CMPO tripodand 11 and CMP

tripodand 12 in 30 and 34% yield, respectively. CMP(O)

tripodands 13 and 14, which have a fourteen carbon chain,

were obtained in 23 and 33% yield, respectively, by reaction of

CMPO tripodand 9 and CMP tripodand 10 with myristoyl

chloride. The tripodands 15 and 16, which have a handle for

the connection of COSAN moieties, were prepared by reaction

of 9 and 10 with 6-chlorohexanoyl chloride in 68 and 27%

yield, respectively. The formation of CMP(O) tripodands

11–14 was conﬁrmed, in addition to the FAB mass spectra,

by the appearance in the ¹H NMR spectra of two signals

belonging to the alkyl chain, viz. a multiplet of the methylene

groups at B1.2–1.3 ppm and a triplet of the methyl groups at

Using a modiﬁed literature procedure, trimethylolpropane

17, was converted in two steps to methyl ester 19¹⁰in 83%

overall yield. Amidation of ester 19 with ammonia in methanol

aﬀorded tripodal amide 20 in 69% yield, which subsequently

was reduced to tripodal amine 21 in 98% yield. Acylation of

amine 21 followed by an Arbusov reaction resulted in the

introduction of the desired CMP(O) moieties to give 23 and 24

in 38 and 56% yield, respectively.

Potentiometric measurements

Recently, we reported potentiometric measurements with N-

acyl(thio)urea- and picolin(thio)amide-functionalized tripo-

dands.⁸Similar measurements, concerning complex formation

within the polymeric membrane phase and the potentiometric

selectivity of ion selective electrodes (ISEs), were performed

with tripodands 3 and 4. The studied cations (Eu³⁺, Cu²⁺

,

Cd²⁺, Pb²⁺, UO₂

and Na⁺) were selected for their pre-

2+

sence in nuclear waste, as well as for their diﬀerence in charge

and physical properties.

The complex formation constants were determined by

means of the segmented sandwich method.¹¹The values of

the complex formation constants (expressed as log b_ML) for

ionophores 3 and 4 and selected cations are collected in Table

1. They show that CMPO tripodand 3 forms stronger com-

plexes than CMP tripodand 4 with all the examined cations,

following the expected trend of the complexation properties

for P-containing compounds: phosphine oxide > phosphate

> phosphonate.¹²The largest complex formation constant,

log b_ML, of CMPO tripodand 3 was found for Eu³⁺, which

was taken as a general representative for the trivalent actinides

1

B0.8 ppm. The H NMR spectrum of 15 exhibits a triplet at

3.39 ppm for the CH₂Cl group, while in the case of 16 this

signal is hidden under the multiplet at 3.29–3.58 ppm.

To study the possible inﬂuence of the spacer length between

the oxygen and the amide atom on the complexation behavior,

the tripodal derivatives 23 and 24 were prepared (Scheme 4).

These compounds have one carbon atom shorter spacers

compared to the corresponding CMP(O) tripodands 3 and 4.

Scheme 2

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Scheme 3

2+

(Am³⁺and Cm³⁺) and lanthanides. In contrary, the aﬃnity

of CMP 4 to Eu³⁺is quite weak.

of ions). This is especially seen for UO₂

and Na⁺. The

CMP(O) tripodands 3 and 4 exhibit the highest selectivity

towards UO₂²⁺, which is in agreement with the essentially

2+

greater stability constants for complexes with UO₂

Pb²⁺(see Table 1). The selectivity found for UO₂

Pb²⁺ions for membranes based on 3 and 4 is even better than

that reported for CMP(O) tetrakis-functionalized cavitands.¹⁴

The much weaker, compared to Pb²⁺, interaction between

Na⁺and tripodands 3 and 4 results in a signiﬁcantly increased

selectivity of the electrodes for Pb²⁺over Na⁺compared to

CMP(O) tripodands 3 and 4 were examined as ionophores

in o-NPOE/PVC membranes also containing 30% mol of

lipophilic anionic additives. The unbiased selectivity coeﬃ-

cients, K^p_I,^o_J^t, values were obtained in the same way as described

than

2+

over

earlier.⁸The logarithmic values of the selectivity coeﬃcients,

pot

Pb,J

calculated for Pb²⁺as the primary cation (log K ) and Na⁺,

Cu²⁺, Cd²⁺and UO₂as interfering ions, are presented in

2+

Fig. 1. It is well known that the ion-ionophore interactions,

that can be expressed by the relative stability constants of

complexes formed by an ionophore with primary and inter-

fering ions within the membrane phase, are the main factor

that is primarily responsible for the selectivity of polymeric

membranes without ionophore. The much less pronounced

values in the case of Cu²⁺and Cd²⁺

,

pot

changes in log K

Pb,J

observed for membranes doped with CMPO 3 or CMP 4, can

be explained by a similar stability of the complexes formed by

these tripodands with Cu²⁺, Cd²⁺and Pb²⁺

.

membrane electrodes.¹³The obtained selectivity patterns:

2+

UO₂

> Pb²⁺> Cd²⁺> Cu²⁺c Na⁺for CMPO

Extraction experiments

2+

tripodand 3 and UO₂> Pb²⁺> Cu²⁺> Cd²⁺> Na⁺

for CMP tripodand 4 clearly reﬂect this statement. Compar-

ison of the results obtained for membranes only doped with

ion-exchanger (KTFPB) and those containing CMP(O) tripo-

dands 3 or 4 as ionophore, reveals that the examined tripo-

dands are able to induce selectivities that diﬀer from the so-

called Hofmeister series (based on the relative hydrophobicity

Extraction of diﬀerent types of cations. To obtain initial

insight into the extraction properties of the CMP(O) tripo-

dands 3 and 4, the extraction of a number of cations (Na⁺,

K⁺, Ag⁺, Ca²⁺, Cd²⁺, Hg²⁺, Pb²⁺, Cu²⁺, Eu³⁺and Fe³⁺

was investigated. In the extraction studies, Eu³⁺was selected

)

as a general representative for the trivalent actinides (e.g.

Scheme 4

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Table 1 Formal complex formation constants, log b_ML, obtained

with ionophores 3 and 4 in PVC/o-NPOE (1 : 2) membranes, using

the segmented sandwich method

a

log b_ML

Cation

CMPO (3)

CMP (4)

Na⁺

8.4

19.8

19.1

17.4

21.5

28.3

4.8

11.8

9.3

9.0

12.3

7.9

Cu²⁺

Cd²⁺

Pb²⁺

2+

UO₂

Eu³⁺

a

Standard deviations r0.3 (from at least three replicate measure-

ments). The stoichiometries of the ion : ionophore was assumed to be

1 : 1.

Fig. 2 Extraction results of CMP(O) tripodands 3 and 4. Conditions:

[L]_o,j= 10^ꢂ3M in CH₂Cl₂; [Mⁿ⁺

[HNO₃]_w= 10^ꢂ3M; pH 3.

]

= 10^ꢂ3M; [LiPic]_w= 10^ꢂ4M;

w,j

Am³⁺and Cm³⁺) and lanthanides, while the other cations

were selected for their diﬀerence in charge and physical

properties. The results of the picrate extractions¹⁵are sum-

marized in Fig. 2.

CMP(O) tripodands 11–14 have a long alkyl chain to enhance

the solubility. However, CMP tripodands 4, 12 and 14 form

precipitates when dissolved in TCE and contacted with acidic

aqueous solutions.

The extraction percentages (%E values) reported in Fig. 2

show that CMP tripodand 4 has a very similar extraction

behavior towards the diﬀerent cations used. CMPO tripodand

3 has a higher aﬃnity for Eu³⁺than for the other cations,

while it has the lowest aﬃnity for Ag⁺. The reason for this is

that the CMPO ligating groups of 3 have hard donor atoms,

while Ag⁺is a soft donor cation (Pearson’s principle).¹⁶

Table 2 shows the Eu³⁺and Am³⁺extraction data of the

CMPO tripodands 3, 11 and 13. The data show that the

introduction of a long alkyl chain does not enhance the

extraction properties of CMPO tripodand 3 (3 vs. 11 and 13)

due to a better complex solubility. The extraction properties

are comparable to those of the malonamides used in the

DIAMEX process (0.65 M N,N⁰-dimethyl-N,N⁰-dioctyl-2-hex-

ylethoxymalonamide (DMDOHEMA) in hydrogenated

tetrapropene (TPH) at 1 M HNO₃), with D_Am= 0.2 and

D_Eu= 0.1.

Extraction of americium and europium. Extraction experi-

ments of Am³⁺and Eu³⁺were performed at ﬁrst instance

with o-nitrophenyl octyl ether (NPOE) as the organic phase at

varying nitric acid concentrations, imposed by the need to

simulate the strongly acidic conditions required in the repro-

cessing of nuclear waste. However, with NPOE as a solvent no

reliable extraction data could be obtained due to the occur-

rence of precipitates. In a few cases precipitation was assumed

based on the bad activity mass balances.

More diluted TCE solutions of the CMP tripodands 4, 12

and 14 were also tested to prevent third phase formation. Even

at a low concentration of 6.8 ꢁ 10^ꢂ4M CMP tripodand 4

could not be measured due to the appearance of a precipitate,

when the organic layer is mixed with the HNO₃solution.

However, in the case of compound 12, at a ligand concentra-

tion of 5.6 ꢁ 10^ꢂ4M in TCE, extraction of Am³⁺and Eu³⁺

from 0.1–3 M HNO₃was possible, although the distribution

coeﬃcients were very low (1.1 ꢁ 10^ꢂ3–3.9 ꢁ 10^ꢂ3). The

extraction eﬃciency of CMP tripodand 14 could be measured

at a somewhat higher concentration (1.9 ꢁ 10^ꢂ3M) to give

distribution coeﬃcients for Eu³⁺and Am³⁺of 2.1 ꢁ 10^ꢂ3and

3 ꢁ 10^ꢂ3, respectively, at 3 M HNO₃(precipitation occurred at

lower concentrations).

In order to avoid third phase formation, similar extractions

were performed from 1 M HNO₃into 1,1,2,2-tetrachloro-

ethane (TCE) with CMP(O) tripodands 3, 4 and 11–14.

All ionophores are well-soluble in 1-octanol. However, from

the extraction data collected in Table 3, it is clear that the

Table 2 Distribution coeﬃcients and separation factors for the

extraction of Eu³⁺and Am³⁺by CMPO tripodands 3, 11 and 13 in

TCE^a

Ionophore

Cation

3

11

13

Eu³⁺

Am³⁺

S_Am/Eu

a

0.26

0.51

2.0

0.33

0.64

1.9

0.27

0.52

1.9

Fig. 1 Selectivity coeﬃcients for electrodes prepared with PVC/

o-NPOE (1 : 2 by weight) membranes containing CMP(O) tripodands

3, 4 and lipophilic sites (KTFPB) as well as membranes with ion-

exchanger only, with Pb²⁺as the primary ion.

Aqueous phase: ¹⁵²Eu and ²⁴¹Am trace level in 1 M [HNO₃]. Organic

phase: ligand (1.4 ꢁ 10^ꢂ2M 3, 1.7 ꢁ 10^ꢂ2M 11 and 1.2 ꢁ 10^ꢂ2M 13)

in TCE.

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Table 3 Distribution coeﬃcients and separation factors for the extraction of Eu³⁺and Am³⁺by CMP(O) tripodands 3, 11–14, 23 and 24 in

1-octanol^a

HNO₃/M

1.37

HNO₃/M

0.98

Ionophore

Cation

2.70

Ionophore

Cation

3.07

3

Eu³⁺

3.6 ꢁ 10^ꢂ3

6.9 ꢁ 10^ꢂ3

1.9

1.3 ꢁ 10^ꢂ3

2.1 ꢁ 10^ꢂ2

1.6

4

Eu³⁺

o10^ꢂ3

—

9.9 ꢁ 10^ꢂ2

1.0 ꢁ 10^ꢂ2

1.0

Am³⁺

S_Am/Eu

Am³⁺

S_Am/Eu

11

13

Eu³⁺

3.5 ꢁ 10^ꢂ3

6.8 ꢁ 10^ꢂ3

1.9

1.1 ꢁ 10^ꢂ2

1.7 ꢁ 10^ꢂ2

1.6

12

14

24

Eu³⁺

o10^ꢂ3

—

2.6 ꢁ 10^ꢂ3

3.0 ꢁ 10^ꢂ3

1.1

Am³⁺

S_Am/Eu

Am³⁺

S_Am/Eu

Eu³⁺

4.2 ꢁ 10^ꢂ3

8.9 ꢁ 10^ꢂ3

2.1

1.1 ꢁ 10^ꢂ2

1.9 ꢁ 10^ꢂ2

1.8

Eu³⁺

o10^ꢂ3

—

1.6 ꢁ 10^ꢂ3

1.5 ꢁ 10^ꢂ3

0.9

Am³⁺

S_Am/Eu

Am³⁺

S_Am/Eu

23

Eu³⁺

2.4 ꢁ 10^ꢂ3

4.5 ꢁ 10^ꢂ3

1.9

6.7 ꢁ 10^ꢂ3

1.1 ꢁ 10^ꢂ2

1.6

Eu³⁺

o10^ꢂ3

—

o10^ꢂ3

—

Am³⁺

S_Am/Eu

Am³⁺

S_Am/Eu

a

In all cases the ligand concentration is 10^ꢂ3M.

distribution coeﬃcients (of 3, 11 and 13) are much lower in the

polar 1-octanol than in TCE. Furthermore, gel formation

occurred when using a higher concentration of CMPO tripo-

dand 3 in 1-octanol (10^ꢂ2M).

tripodands 9 and 10. As can be expected, only uncharged

zwitterionic compounds result, in which the tripodal part is

separated from the COSAN anion by a protonated amino

group and the eﬀect of the anionic charge is shielded. Com-

pounds 28 and 29 were prepared in moderate yields by

alkylation of the terminal OH group of the diethyleneglyco-

lyl-substituted COSAN 25b (reacted as dry disodium salt

generated from the corresponding Me₃NH⁺salt in THF by

addition of two equivalents of NaH) with chloroalkyl group-

containing tripodands 15 and 16, respectively (Scheme 5). Due

to the presence of the carboxamide group in the connecting

arm, these compounds tend to be protonated to give the

respective uncharged enol-forms. Nevertheless, it can be as-

sumed that compounds 28 and 29 can act as real anions in

extractions at low acidity. This can be concluded from the

COSAN moieties covalently linked to CMP(O) tripodands.

In order to enhance the extraction ability of CMP(O) tripo-

dands 3 and 4, as well as the solubility in the case of 4, the

hydrophobic cobalt bis(dicarbollide) anion (COSAN) was

covalently attached to amino terminated (9, 10) and chloro-

alkyl-containing CMP(O) tripodands 15 and 16 to give 26, 27

and 28, 29, respectively (Scheme 5). Compounds 26 and 27

were prepared by ring opening of the reactive COSAN-diox-

ane 25a, which is known to serve as a versatile building block

for many applications,¹⁷by the terminal amino group of the

Scheme 5

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Table 4 Distribution coeﬃcients for the extraction of Eu³⁺and

Am³⁺by CMP(O) tripodands 3 and 4 and their synergistic mixtures

with bromo-COSAN in nitrobenzene

Table 5 Distribution coeﬃcients for the extraction of Eu³⁺and

Am³⁺by COSAN-containing CMP(O) tripodands 28 and 29 in

nitrobenzene

HNO₃/M

Compound^a

0.01

0.1

1.0

3.0

Ionophore^a

0.001 0.01

0.1

1.0

3.0

3

D_Eu0.57

D_Am1.01

0.43

0.72

1.31

2.38

4.03

6.97

28

D_Eu>10³346

D_Am>10³414

18.0 5.68 ꢁ 10^ꢂ22.05 ꢁ 10^ꢂ2

25.8 9.78 ꢁ 10^ꢂ22.76 ꢁ 10^ꢂ2

3 + HBBr D_Eu>10³

D_Am>10³

>10³

222

357

29

D_Eu>10³>10³3.55 2.48 ꢁ 10^ꢂ21.56 ꢁ 10^ꢂ2

D_Am>10³>10³4.80 6.52 ꢁ 10^ꢂ23.20 ꢁ 10^ꢂ2

1.27 ꢁ 10^ꢂ3M 28, 1.43 ꢁ 10^ꢂ3M 29.

a

4

D_Euo10^ꢂ3

o10^ꢂ3

4.50 ꢁ 10^ꢂ3

D_Am1.36 ꢁ 10^ꢂ31.25 ꢁ 10^ꢂ31.08 ꢁ 10^ꢂ38.14 ꢁ 10^ꢂ3

4 + HBBr D_Eu>10³

>10³

14.3

16.0

1.04

1.82

CMP(O) tripodand-containing magnetic particles. Recently,

a new separation technology was introduced for nuclear waste

treatment, viz. magnetically assisted chemical separation with

extractant coated particles.¹⁸It combines the selectivity of a

ligand used for liquid–liquid extractions with improved phase

separation due to the magnetic ﬁeld, resulting in an eﬀective

system that provides only a small volume of high level waste.

The magnetic particles can be directly vitriﬁed or stripped, to

enable their re-use in an automated process. Fundamental

studies have been performed by Nunez and Kaminski

et al.^19–21The better extraction properties (B12-fold)^22,23

obtained with calix[4]arenes bearing four CMPO groups cova-

lently bound to the particle surface in comparison with

particles with adsorbed CMPO moieties, inspired our alter-

native strategy of covalent attachment of CMP(O) tripodal

ionophores on the surface of magnetic particles for

Eu³⁺/Am³⁺separation from high activity liquid wastes.

In order to achieve a further increase of the lanthanide and

actinide extraction capacity of functionalized magnetic parti-

cles, starburst dendrimers have been introduced on the particle

surface. These dendrimer coated magnetic particles have a

high potential for immobilization of a large variety of selective

chelators in a very high density on the particle surface.²⁴The

extraction studies for Eu³⁺and Am³⁺were carried out under

highly acidic conditions with Eu³⁺and Am³⁺solutions found

in real waste.

D_Am>10³

>10³

a

1 ꢁ 10^ꢂ3M 3, 4 and 3 ꢁ 10^ꢂ3M HBBr (bromo-COSAN).

increase of its extraction properties in the low acidity

range, compared to those of the former couple of compounds

26 and 27.

Extraction experiments of Am³⁺and Eu³⁺from HNO₃

solutions were performed with COSAN-containing CMP(O)

tripodands 26 and 27. CMPO derivative 26 gave low distribu-

tion coeﬃcients, D_Am= 0.4 and D_Eu= 0.3 (5.6 ꢁ 10^ꢂ3M 26

in toluene, 0.1 M HNO₃). The distribution coeﬃcients for

Eu³⁺with COSAN-containing CMP tripodand 27 in nitro-

benzene (8.1 ꢁ 10^ꢂ4M) at 0.1 and 1 M HNO₃, are 311 and

4.55, respectively, indicating a good extraction ability. The

extraction results of an equimolar synergistic mixture of 3 and

4 with bromo-COSAN are given in Table 4. CMP tripodand 4

itself does not extract Eu/Am at all over the range of acidities.

In the synergistic mixture with bromo-COSAN, the distribu-

tion ratios are several orders of magnitude higher. CMPO

tripodand 3 itself exhibits a modest Eu/Am extraction, while

the presence of bromo-COSAN again leads to an enormous

increase of the extraction ability. These results demonstrate

the importance of the presence of COSAN, either in a syner-

gistic mixture or covalently bound. The attachment of

COSAN moieties to the CMP(O) tripodand derivatives, 26

and 27, gives rise to modest extraction properties at higher pH.

Due to eﬀect of the COSAN acidity, the secondary amine is

always protonated, and consequently compounds 26 and 27

are not negatively charged. This assumption is supported by

the results obtained with synergistic mixtures (no amine group

present). However, the linkage of COSAN to the CMP

tripodand 27 makes it more soluble and no precipitation was

formed during the Eu³⁺extraction experiments. In the case of

compounds 28 and 29, good extraction properties can be

observed for acidities up to 0.1 M. The consecutive increase

of the acid concentration leads in both cases to a signiﬁcant

drop of the distribution ratio, as can be seen from the results

presented in Table 5.

CMP(O) tripodand-containing magnetic particles were pre-

pared by reaction of CMP(O) tripodands 9 and 10 with

magnetic particles functionalized with third generation den-

drimers 30 (Scheme 6).

The distribution coeﬃcient K_Dfor solid/liquid extractions is

deﬁned as:

ðC_L;0ꢂ C_LÞ V_L

K_D

¼

C_L

m_s

Due to saturation phenomena, these K_Dvalues are usually not

constant and thus only values obtained under identical con-

ditions (concentration in the liquid phase, amount of solid

phase) can be compared. Therefore the distribution coeﬃ-

cients (K_D) for Eu³⁺and Am³⁺extraction with magnetic

particles (m_s) with 10 mL (V_L) of Eu³⁺or Am³⁺containing

test solution of known activity (C_L) were measured in the

supernatant. The results of the extraction experiments with

CMP(O) tripodand modiﬁed particles 31 and 32 towards

Am³⁺and Eu³⁺are given in Table 6.

The decrease of the extraction eﬀectivity at higher acidities

may be due to the length of the linker between COSAN and

the tripodand moieties or again to the presence of an amide

group (possible protonation). The separation factors D_Am/D_Eu

for 28 and 29 vary in the range 1–2.5.

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actinides (UO₂²⁺, Am³⁺) and Eu³⁺than CMP tripodand 4,

that has a very high complex formation constant for Eu³⁺

(log b_ML= 28.3).

Extractions of Am³⁺and Eu³⁺suﬀer from precipitate and

third phase formation in NPOE as the organic phase. In the

case of the CMP tripodands attachment of a long alkyl chain

and going to TCE as an organic solvent does not improve. In

the case of the CMPO tripodands 3, 11 and 13 reasonable

extraction data were obtained using TCE. However, with the

more polar 1-octanol as the extraction solvent, all tripodands

dissolved, but gave rise to poor extraction results. The dis-

tribution coeﬃcients were considerably enhanced upon addi-

tion of bromo-COSAN as a synergistic agent. However, in the

case the COSAN is covalently attached to the tripodand, the

eﬀect on the extraction is strongly dependent on the HNO₃

concentration.

Dendrimer-coated magnetic silica particles functionalized

on the surface with CMPO tripodand 31 have high distribu-

tion coeﬃcients for Am³⁺and Eu³⁺extraction at low HNO₃

concentration, which may make it a promising system for

industrial development.

Scheme 6

Experimental

The CMPO tripodand bearing particles 31 are very eﬀective

for Eu³⁺and Am³⁺at 0.01 M HNO₃and have a selectivity

factor of 3.7 at 0.1 M HNO₃. CMP tripodand bearing particles

32 are not so eﬀective as 31, but they have a higher separation

factor at 0.01 M HNO₃(2.5 vs. 1 for 31). At HNO₃concen-

trations higher than 0.01 M the distribution coeﬃcients de-

crease to values lower than 1, abruptly in the case of CMP

tripodand bearing particles 32, and gradually for CMPO

tripodand bearing particles 31. The distribution coeﬃcients

for CMPO tripodand bearing particles 31 at 3 M HNO₃are

much lower than those reported for simple CMPO-bearing

particles (K_D= 23 and 48 for Eu³⁺and Am³⁺, respec-

tively).²⁵However, the high distribution coeﬃcients of the

CMPO tripodand bearing particles at low HNO₃concentra-

tions constitute a system for potential future industrial devel-

opment.

General

¹H and ¹³C NMR spectra were recorded on a Varian Unity

INOVA (300 MHz) and a Varian Unity 400 WB NMR

spectrometer, respectively. All spectra were recorded in CDCl₃

unless otherwise stated. ¹¹B NMR spectra were recorded on a

Varian Mercury Plus 400 MHz spectrometer in deuterioace-

tone. Residual solvent protons were used as an internal

standard and chemical shifts are given in ppm relative to

tetramethylsilane (TMS). Fast atom bombardment (FAB)

mass spectra were measured on a Finnigan MAT 90 spectro-

meter using m-nitrobenzyl alcohol (NBA) as a matrix. Matrix-

assisted laser desorption ionisation time-of-ﬂight (MALDI-

TOF) mass spectra were recorded using a Perkin Elmer/

PerSpective Biosystems Voyager-DE-RP MALDI-TOF mass

spectrometer. Elemental analyses were carried out using a

1106 Carlo-Erba Strumentazione element analyser. All sol-

vents were puriﬁed by standard procedures. All other chemi-

cals were analytically pure and were used without further

puriﬁcation. All reactions were carried out under an inert

argon atmosphere. Melting points (uncorrected) of all com-

pounds were obtained on a Reichert melting point apparatus.

Compounds 1²⁶and 5⁹were prepared following a literature

procedure. The COSAN derivatives 25a²⁷and 25b²⁸were

prepared as reported previously.

Conclusions

C₃-Symmetric tris-CMP(O) ligand systems 3, 4, 11–16, 23 and

24 were developed. Liquid–liquid extractions and ISE data

demonstrated that CMPO tripodand 3 has a higher aﬃnity for

Table 6 Distribution coeﬃcients for the extraction of Am³⁺and

Eu³⁺by microparticles 31 and 32 bearing CMP(O) tripodands on the

surface^a

Syntheses

HNO₃concentration/M

Particle type

Cation

0.01

0.1

1

3

1,1,1-Tris[(chloroacetamidopropoxy)methyl]propane (2). To

a

solution of 1,1,1-tris[(aminopropoxy)methyl]propane 1

31

Eu³⁺

1215

1359

221

59

1.5

2.1

o1

Am³⁺

(865 mg, 2.84 mmol) and Et₃N (6.4 mL, 45.6 mmol) in CH₂Cl₂

(50 mL) was added chloroacetyl chloride (2.75 mL, 34.6

mmol), and the reaction mixture was heated at reﬂux over-

night. The solution was washed with 1 M HCl (2 ꢁ 25 mL),

H₂O (2 ꢁ 25 mL), 2 M NaOH (3 ꢁ 25 mL) and 1 M HCl (2 ꢁ

25 mL) and dried over MgSO₄. Evaporation of the solvent

32

Eu³⁺

102

256

o1

Am³⁺

a

Extraction conditions: Aqueous phase: 10 mL of HNO₃+ ¹⁵²Eu +

²⁴¹Am; mass of particles 300 mg; stirring time: 1 h.

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aﬀorded 2 as a pale yellow oil. Yield 813 mg (54%); FAB-MS:

m/z 535.4 ([M + H]⁺, calc. 535.1); ¹H NMR d: 6.96–6.98 (m,

3H, NH), 4.06 (s, 6H, CH₂Cl), 3.50 (t, 6H, J = 6.0 Hz,

OCH₂), 3.43 (q, 6H, J = 6.0 Hz, CH₂NH), 3.34 (s, 6H,

CCH₂O), 1.82 (q, 6H, J = 6.0 Hz, CH₂), 1.46 (q, 2H, J =

7.7 Hz, CH₂), 0.85 (t, 3H, J = 7.7 Hz, CH₃); ¹³C NMR d:

165.8, 71.8, 70.0, 42.7, 38.2, 37.9, 29.1, 23.2, 7.7.

Cbz-CMPO-tripodand 7. In an open ﬂask compound 6 (300

mg, 0.76 mmol) was dissolved in a small amount of ethyl

diphenylphosphinite (0.6 mL, 5.0 mmol), while the tempera-

ture was gradually increased from 100 to 150 1C. Subse-

quently, the mixture was stirred for 1 h at 150 1C. After

cooling of the reaction mixture, diisopropyl ether was added

till a precipitate was formed. The precipitate was ﬁltered oﬀ

and dissolved in CH₂Cl₂in order to collect all product from

the ﬁlter. The organic solvent was evaporated to give 7 as a

light brown solid. Yield 703 mg (94%); mp 58–60 1C; FAB-

MS: m/z 1153.5 ([M + H]⁺, calc. 1153.0); ¹H NMR d:

7.70–7.80 and 7.42–7.54 (2m, 12 + 18H, P-phenyl), 7.28 (s,

5H, ArH), 5.32 (s, 2H, OCH₂Ar), 3.65 (s, 6H, CCH₂O), 3.35

(t, 6H, J = 6.0 Hz, OCH₂), 3.30 (d, 6H, J = 13.2 Hz, CH₂P),

3.25 (q, 6H, J = 6.0 Hz, CH₂NH), 1.62 (q, 6H, J = 6.0 Hz,

CH₂); ¹³C NMR d: 164.6, 155.5, 136.8, 132.2, 131.0, 130.8,

128.8, 128.7, 128.5, 128.4, 69.6, 69.3, 65.3, 46.2, 38.6, 37.5,

29.2. Anal. Calc. for C₆₃H₇₁N₄O₁₁P₃ꢃ 1/2CH₂Cl₂: C, 63.79; H,

6.07; N, 4.69. Found: C, 63.30; H, 5.93; N, 4.23%.

1,1,1-Tris[(diphenylcarbamoylmethylphosphine oxide N-pro-

poxy)methyl]propane (3). In an open ﬂask compound 2 (933

mg, 1.25 mmol) was dissolved in a small amount of ethyl

diphenylphosphinite (1 mL, 4.125 mmol), while the tempera-

ture was gradually increased from 100 to 150 1C. Subse-

quently, the mixture was stirred for 1 h at 150 1C. After

cooling of the reaction mixture, diisopropyl ether was added

till a precipitate was formed. The precipitate was ﬁltered oﬀ

and dissolved in CH₂Cl₂(50 mL) in order to take all the

compound from the ﬁlter. The organic solvent was removed in

vacuo yielding 3 as a light brown solid. Yield 1.07 g (83%); mp

130–132 1C; FAB-MS: m/z 1032.7 ([M + H]⁺, calc. 1032.4);

¹H NMR d: 7.70–7.82 and 7.45–7.51 (2m, 12 + 18H, P-

phenyl), 3.40 (d, 6H, J = 13.2 Hz, CH₂P), 3.21–3.31 (m,

12H, OCH₂+ CH₂NH), 3.15 (s, 6H, CCH₂O), 1.62 (q, 6H,

J = 6.6 Hz, CH₂), 1.33 (q, 2H, J = 7.3 Hz, CH₂), 0.79 (t, 3H,

J = 7.3 Hz, CH₃); ¹³C NMR d: 162.0, 132.0, 131.0, 130.0,

128.0, 71.0, 68.0, 42.0, 39.0, 38.0, 37.5, 36.0, 22.5, 7.0. Anal.

Calc. for C₅₇H₆₈N₃O₉P₃ꢃ 1/2CH₂Cl₂: C, 64.27; H, 6.47; N,

3.91. Found: C, 64.76; H, 6.17; N, 3.82%.

Cbz-CMP-tripodand 8. In an open ﬂask compound 8 (500

mg, 0.76 mmol) was dissolved in a small amount of triethyl

phosphite (0.86 mL, 5.01 mmol), while the temperature was

gradually increased from 100 to 150 1C. Subsequently, the

mixture was stirred for 1 h at 150 1C. After cooling of the

reaction mixture diisopropyl ether was added and left stirring

overnight. The organic solution was decanted to give com-

pound 8 as a brown oil. Yield 438 mg (60%). FAB-MS: m/z

962.3 ([M + H]⁺, calc. 962.4); ¹H NMR d: 7.31 (s, 5H, ArH),

5.29 (s, 2H, OCH₂Ar), 4.10 (q, 12H, J = 7.1 Hz, OCH₂), 3.66

(s, 6H, CCH₂O), 3.49 (t, 6H, J = 5.5 Hz, OCH₂), 3.31 (q, 6H,

J = 5.5 Hz, CH₂NH), 2.79 (d, 6H, J = 20.8 Hz, CH₂P), 1.74

1,1,1-Tris[(diethylcarbamoylmethylphosphonate N-propoxy)-

methyl]propane (4). In an open ﬂask compound 2 (813 mg, 1.52

mmol) was dissolved in a small amount of triethyl phosphite

(0.86 mL, 5.01 mmol), while the temperature was gradually

increased from 100 to 150 1C. Subsequently, the mixture was

stirred for 1 h at 150 1C. After cooling of the reaction mixture,

diisopropyl ether was added and the mixture left stirring

overnight. The organic solution was decanted remaining 4 as

a brown oil. Yield 1.13 g (89%). FAB-MS: m/z 839.4 ([M +

H]⁺, calc. 839.0); ¹H NMR d: 4.16 (q, 12H, J = 7.1 Hz,

OCH₂), 3.46 (t, 6H, J = 6.0 Hz, OCH₂), 3.35 (q, 6H, J = 6.0

Hz, CH₂NH), 3.27 (s, 6H, CCH₂O), 2.85 (d, 6H, J = 20.8 Hz,

CH₂P), 1.78 (q, 6H, J = 6.0 Hz, CH₂), 1.20–1.36 (m, 18 + 2H,

CH₃+ CH₂), 0.84 (t, 3H, J = 7.1 Hz, CH₃); ¹³C NMR

d: 163.0, 71.0, 68.0, 62.0, 42.5, 37.0, 36.0, 34.0, 28.5, 22.5,

18.0, 7.5.

(q, 6H, J = 5.5 Hz, CH₂), 1.29 (t, 18H, J = 7.1 Hz, CH₃); ¹³

C

NMR d: 163.5, 154.9, 135.9, 127.8, 127.4, 69.2, 68.8, 65.6, 61.9,

58.3, 36.9, 33.6, 28.4, 15.7.

Amino-CMPO-tripodand 9. A suspension of compound 7

(632 mg, 0.64 mmol) and 10% Pd/C (98 mg) in MeOH (25 mL)

was stirred under a hydrogen atmosphere overnight. The

reaction mixture was ﬁltered over Celite and washed thor-

oughly with small portions of MeOH. Removal of the solvent

gave a solid, which was redissolved in CH₂Cl₂. Evaporation of

CH₂Cl₂aﬀorded 9 as a light yellow solid. Yield 500 mg (87%);

mp 70–72 1C; MALDI-MS: m/z 1019.4 ([M + H]⁺, calc.

1019.0); ¹H NMR d: 7.70–7.80 and 7.42–7.54 (2m, 12 + 18H,

P-phenyl), 3.64 (s, 6H, CCH₂O), 3.36–3.39 (m, 6H, OCH₂),

3.30 (d, 6H, J = 13.2 Hz, CH₂P), 3.24–3.28 (m, 6H, CH₂NH),

1.62 (q, 6H, J = 5.7 Hz, CH₂); ¹³C NMR d: 164.2, 131.2,

130.8, 128.8, 128.0, 69.9, 62.8, 59.0, 37.7, 37.2, 29.1, 28.4.

Anal. Calc. for C₅₅H₆₅N₄O₉P₃ꢃ 3/4CH₂Cl₂: C, 61.84; H, 6.19;

N, 5.17. Found: C, 62.15; H, 5.82; N, 5.43%.

Cbz-chloroacetamido-tripodand 6. To a solution of carba-

mate 5 (526 mg, 1.23 mmol) and Et₃N (2.2 mL, 16 mmol) in

CH₂Cl₂(35 mL) was added chloroacetyl chloride (1.27 mL,

12.3 mmol), and the reaction mixture was reﬂuxed overnight.

The solution was washed with 1 M HCl (2 ꢁ 20 mL), H₂O (2 ꢁ

20 mL), 2 M NaOH (3 ꢁ 20 mL), and 1 M HCl (2 ꢁ 20 mL)

and dried over MgSO₄. Evaporation of the solvent aﬀorded 6

as a pale yellow oil. Yield 795 mg (98%); FAB-MS: m/z 657.5

([M + H]⁺, calc. 657.3); ¹H NMR d: 7.33 (s, 5H, ArH),

6.97–6.99 (m, 3H, NH), 5.03 (s, 2H, CH₂), 4.06 (s, 6H,

CH₂Cl), 3.69 (s, 6H, CCH₂O), 3.51 (t, 6H, J = 5.8 Hz,

OCH₂), 3.37 (q, 6H, J = 5.8 Hz, CH₂NH), 1.77 (q, 6H,

J = 5.8 Hz, CH₂); ¹³C NMR d: 165.6, 154.6, 135.1, 127.9,

127.51, 69.4, 65.8, 58.1, 42.1, 37.4, 28.4.

Amino-CMP-tripodand 10. A suspension of compound 8

(185 mg, 0.19 mmol) and 10% Pd/C (98 mg) in MeOH (20 mL)

was stirred under a hydrogen atmosphere overnight. The

reaction mixture was ﬁltered over Celite and washed thor-

oughly with small portions of MeOH. Removal of the solvent

gave 10 as a brown oil. Yield 135 mg (85%); MALDI-MS: m/z

827.2 ([M + H]⁺, calc. 827.0); ¹H NMR d: 4.16 (q, 12H, J =

7.1 Hz, OCH₂), 3.65 (s, 6H, CCH₂O), 3.58 (t, 6H, J = 5.5 Hz,

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OCH₂), 3.42 (q, 6H, J = 5.5 Hz, CH₂NH), 3.05 (d, 6H,

J = 21.2 Hz, CH₂P), 1.74 (q, 6H, J = 5.5 Hz, CH₂), 1.35

(t, 18H, J = 7.1 Hz, CH₃); ¹³C NMR d: 164.2, 70.4, 63.0, 62.7,

37.9, 34.3, 28.4, 16.3.

Myristoyl-CMP-tripodand 14. The general procedure was

applied to 10 (135 mg, 0.16 mmol), myristoyl chloride (0.045

mL, 0.18 mmol) and Et₃N (0.025 mL, 0.18 mmol) to give

compound 14 as a brownish oil. Yield 56 mg (33%); FAB-MS:

1

m/z 1024.6 ([M + Na]⁺, calc. 1024.0); H NMR d: 4.16 (q,

General procedure for the synthesis of tripodands 11–14. A

solution of compounds 9 or 10, nonanoyl chloride or myristoyl

chloride and Et₃N (1.1 equiv.) in CH₂Cl₂(25 mL) was reﬂuxed

for 24 h. Upon cooling the solution was sequentially washed

with a saturated solution of NH₄Cl (2 ꢁ 25 mL), H₂O (2 ꢁ 25

mL), 2 M NaOH (3 ꢁ 25 mL) and a saturated solution of

NH₄Cl (2 ꢁ 25 mL), and dried over MgSO₄. Evaporation of

the solvent aﬀorded the crude compounds. Final puriﬁcation

was performed by preparative TLC (SiO₂, EtOAc–MeOH =

95 : 5; the target compounds remain at the bottom of the

plate). The compounds were removed from the silica with

CH₂Cl₂. Evaporation of the solvent gave the pure compounds

11–14.

12H, J = 6.9 Hz, OCH₂), 3.72 (s, 6H, CCH₂O), 3.50 (t, 6H, J

= 5.8 Hz, OCH₂), 3.28 (q, 6H, J = 5.8 Hz, CH₂NH), 2.88 (d,

6H, J = 20.8 Hz, CH₂P), 2.16–2.19 (m, 2H, CH₂), 1.68 (q, 6H,

J = 5.8 Hz, CH₂), 1.37 (t, 18H, J = 6.9 Hz, CH₃), 1.25–1.27

(m, 22H, CH₂), 0.89 (t, 3H, J = 6.2 Hz, CH₃); ¹³C NMR d:

164.1, 69.8, 69.0, 62.7, 50.8, 37.3, 36.0, 34.3, 31.9, 29.6, 29.3,

29.1, 22.6, 16.4, 14.1.

6-Chlorohexanoyl-CMPO-tripodand 15. To a cold (0 1C)

CH₂Cl₂solution (30 mL) of 9 (751 mg, 0.74 mmol) were added

dry K₂CO₃(1.02 g, 7.38 mmol), 6-chlorohexanoyl chloride

(1.24 g, 7.38 mmol). Subsequently, H₂O (130 mg, 7.22 mmol)

was added in a few small portions over 1 h. The reaction

mixture was allowed to warm up to room temperature and left

for 24 h. After ﬁltration of the solid material and evaporation

of the solvent, the crude product was puriﬁed by column

chromatography (SiO₂, CH₂Cl₂–EtOH–hexane = 84 : 12 : 4)

resulting in pure 15. Yield 576 mg (68%); FAB-HRMS: m/z

1189.4118, ([M + H]⁺, calc. 1189.3944); ¹H NMR d:

7.65–7.72 (m, 12H, PC₆H₅), 7.54 (t, 3H, J = 5.5 Hz,

CH₂NHC(O)C), 7.36–7.49 (m, 18H, PC₆H₅), 6.93 (s, 1H,

CH₂CONHC), 3.58 (s, 6H, CCH₂OCH₂), 3.39 (t, 2H, J =

6.6 Hz, ClCH₂), 3.15–3.34 (m, 18H, C(O)CH₂PO,

Nonanoyl-CMPO-tripodand 11. The general procedure was

applied to 9 (145 mg, 0.14 mmol), nonanoyl chloride (0.03 mL,

0.15 mmol) and Et₃N (0.02 mL, 0.15 mmol) to give compound

11 as a light brown solid. Yield 49 mg (30%); mp 64–66 1C;

FAB-MS: m/z 1181.0 ([M + Na]⁺, calc. 1181.5); ¹H NMR d:

7.62–7.72 and 7.31–7.46 (2m, 12 + 18H, P-phenyl), 3.55 (s,

6H, CCH₂O), 3.15–3.31 (m, 18H, OCH₂, CH₂P, CH₂NH),

2.05–2.10 (m, 2H, CH₂), 1.53 (q, 6H, J = 5.8 Hz, CH₂),

1.13–1.20 (m, 12H, CH₂), 0.80 (t, 3H, J = 6.6 Hz, CH₃); ¹³C

NMR d: 164.0, 130.8, 129.4, 129.3, 127.1, 126.9, 69.6, 69.3,

68.7, 39.2, 38.6, 37.0, 30.0, 27.8, 21.7, 14.1. Anal. Calc. for

C₆₄H₈₁N₄O₁₀P₃ꢃ 2CH₂Cl₂: C, 59.64; H, 6.45; N, 4.22. Found:

C, 59.35; H, 6.35; N, 3.92%.

OCH₂CH₂CH₂N), 2.14 (t, 2H,

J

=

7.4 Hz,

ClCH₂C₃H₆CH₂CO), 1.46–1.69, 1.24–1.34 (m, 12H,

OCH₂CH₂CH₂N, ClCH₂C₃H₆CH₂CO); ¹³C NMR d: 173.2,

164.84, 164.78, 132.6, 132.51, 132.49, 131.2, 131.1, 130.9,

129.1, 128.9, 69.8, 69.1, 60.1, 45.1, 39.5, 38.7, 37.4, 36.8,

32.5, 29.5, 26.6, 25.1.

Nonanoyl-CMP-tripodand 12. The general procedure was

applied to 10 (183 mg, 0.22 mmol), nonanoyl chloride (0.044

mL, 0.24 mmol) and Et₃N (0.03 mL, 0.24 mmol) to give

compound 12 as a brown oil. Yield 73 mg (34%); FAB-MS:

m/z 989.6 ([M + Na]⁺, calc. 989.0); ¹H NMR d: 4.07 (q, 12H,

J = 7.1 Hz, OCH₂), 3.63 (s, 6H, CCH₂O), 3.43 (t, 6H, J = 5.9

Hz, OCH₂), 3.28 (q, 6H, J = 5.9 Hz, 6H, CH₂NH), 2.80 (d,

6H, J = 20.8 Hz, CH₂P), 2.1 (t, 2H, J = 6.9 Hz, CH₂), 1.68 (q,

6H, J = 5.9 Hz, CH₂), 1.27 (t, 18H, J = 7.1 Hz, CH₃),

1.18–1.19 (m, 12H, CH₂), 0.80 (t, 3H, J = 6.9 Hz, CH₃); ¹³C

NMR d: 164.2, 69.8, 69.2, 62.6, 59.7, 37.4, 35.8, 34.5, 31.8,

29.4, 29.2, 25.8, 22.6, 16.4, 14.0.

6-Chlorohexanoyl-CMP-tripodand 16. To a cold (0 1C)

CH₂Cl₂solution (40 mL) of 9 (482 mg, 0.58 mmol) were

added dry K₂CO₃(805 mg, 5.82 mmol) and 6-chlorohexanoyl

chloride (986 mg, 5.83 mmol). Subsequently, H₂O (100 mg,

5.55 mmol) was added in a few small portions over 1 h. The

reaction mixture was allowed to warm up to room temperature

and left for 24 h. After ﬁltration of the solid material and

evaporation of the solvent, the crude product was puriﬁed by

column chromatography (SiO₂, CH₂Cl₂–EtOH–hexane =

84 : 12 : 4) resulting in pure 16. Yield 152 mg (27%). FAB-

1

HRMS: m/z 959.3953, ([M + H]⁺, calc. 959.4080); H NMR

Myristoyl-CMPO-tripodand 13. The general procedure was

applied to 9 (147 mg, 0.14 mmol), myristoyl chloride (0.04 mL,

0.16 mmol) and Et₃N (0.02 mL, 0.16 mmol) to give compound

13 as a light brown solid. Yield 40 mg (23%); mp 60–62 1C;

d: 7.13 (br, 3H, J = 2.7 Hz, CH₂NHCO), 6.66 (s, 1H,

CH₂CONHC), 4.15 (m, 12H, POCH₂CH₃), 3.71 (s, 6H,

CCH₂OCH₂), 3.29–3.58 (m, 14H, OCH₂CH₂CH₂N, ClCH₂),

2.87 (d, 6H, J = 21 Hz, COCH₂PO), 2.23 (t, 2H, J = 7.4 Hz,

ClCH₂C₃H₆CH₂CO), 1.44–1.83 (m, 12H, OCH₂CH₂CH₂N,

ClCH₂C₃H₆CH₂CO), 1.34 (t, 18H, J = 7.1 Hz, POCH₂CH₃);

¹³C NMR d: 173.4, 164.6, 164.5, 70.1, 69.4, 63.0, 62.9, 60.1,

45.1, 37.6, 36.9, 36.2, 34.5, 32.5, 29.5, 26.6, 25.2, 16.6, 16.5.

1

FAB-MS: m/z 1229.8 ([M + H]⁺, calc. 1229.6); H NMR d:

7.61–7.68 and 7.35–7.42 (2m, 12 + 18H, P-phenyl), 3.55 (s,

6H, CCH₂O), 3.31 (t, 6H, J = 6.2 Hz, OCH₂), 3.22 (d, 6H, J

= 13.6 Hz, CH₂P), 3.16 (q, 6H, J = 6.2 Hz, CH₂NH),

1.82–2.00 (m, 2H, CH₂), 1.53 (q, 6H, J = 6.2 Hz, CH₂),

1.13–1.18 (m, 22H, CH₂), 0.80 (t, 3H, J = 6.5 Hz, CH₃); ¹³C

NMR d: 164.6, 132.3, 130.9, 130.8, 128.8, 128.7, 69.6, 69.3,

68.7, 39.2, 38.6, 37.0, 31.8, 29.2, 22.6, 14.1. Anal. Calc. for

C₆₉H₉₁N₄O₁₀P₃ꢃ 5/4CH₂Cl₂: C, 63.18; H, 7.06; N, 4.91.

Found: C, 63.20; H, 6.85; N, 4.73%.

1,1,1-Tris[(carboxymethoxy)methyl]propane (18). A mixture

of trimethylopropane 17 (6.99 g, 52 mmol) and potassium tert-

butoxide (70.0 g, 624 mmol) in tert-butanol (250 mL) was

reﬂuxed for 3 h. Subsequently, bromoacetic acid (43.3 g, 312

mmol) was added dropwise to the mixture over a period of 4 h,

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whereupon the mixture was reﬂuxed for another 140 h. After

solvent evaporation, CH₂Cl₂(100 mL) was added to the

residue and the mixture was acidiﬁed to pH 1 with conc.

HCl. After ﬁltration of the insoluble precipitate, the solvent

was evaporated giving 37.5 g of crude 18, which was used for

the next step without further puriﬁcation.

was decanted to give 23 as a yellow oil, which was puriﬁed by

column chromatography (SiO₂, CH₂Cl₂–MeOH = 10 : 1 -

10 : 2). Yield 229 mg (38%); mp 189–190 1C; ¹H NMR d:

7.70–7.77 (m, 12H, PC₆H₅), 7.65 (br, CH₂NHCO), 7.43–7.56

(m, 18H, PC₆H₅), 3.87 (s, 12H, OCH₂CH₂N), 3.33 (d, 6H, J =

13.2 Hz, CH₂PO), 3.27 (s, 6H, CCH₂O), 1.34 (q, 2H, J = 7.5

Hz, CH₃CH₂), 0.81 (t, 3H, J = 7.5 Hz, CH₃CH₂); ¹³C NMR

d: 165.0, 132.7, 132.5, 131.4, 131.2, 131.0, 129.1, 128.9, 71.3,

69.9, 43.5, 40.0, 38.7, 33.6, 26.6, 8.0. Anal. Calc. for

C₅₄H₆₂N₃O₉ꢃ 1/3 CH₂Cl₂: C, 64.10; H, 6.20; N, 4.13. Found:

C, 64.23; H, 5.99; N, 3.98%.

1,1,1-Tris[(methoxycarbonyl)methyl]propane (19). A solu-

tion of crude 18 and a catalytic amount of H₂SO₄(0.05 mL)

in methanol (250 mL) was reﬂuxed for 48 h (reﬂux passed

through a bed of molecular sieves 3A). After evaporation of

the methanol, the residue was dissolved in CH₂Cl₂(10 mL)

and passed through a layer of silica gel. Evaporation of the

solvent aﬀorded crude ester 19 as a yellow oil, which was used

in the next step without further puriﬁcation. Yield 15.2 g (83%

based on alcohol 17).

1,1,1-Tris[(diethylcarbamoylmethylphosphonate N- ethoxy)-

methyl]propane (24). In an open ﬂask compound 22 (438 mg,

0.889 mmol) was dissolved in a small amount of triethyl

phosphite (0.78 mL, 4.46 mmol), while the temperature was

gradually increased from 100 to 150 1C. Subsequently, the

mixture was stirred for 1 h at 150 1C. After cooling of the

reaction mixture, diisopropyl ether was added and the mixture

left stirring overnight. The organic solution was decanted

remaining a yellow oil, which was puriﬁed by column chro-

matography (SiO₂, CH₂Cl₂–i-PrOH = 10 : 2). Yield 400 mg

(56%). FAB-HRMS: m/z 798.3533, ([M + H]⁺, calc.

798.3472); ¹H NMR d: 7.14 (t, 3H, J = 4.8 Hz, CH₂NH),

4.14 (dq, 12H, J_q= 7.2 Hz, J_d= 8.1 Hz, POCH₂CH₃),

3.15–3.42 (m, 12H, OCH₂CH₂NH), 3.32 (s, 6H, CCH₂O), 2.86

(d, 6H, J = 20.7 Hz, CH₂PO), 1.39 (q, 2H, J = 7.5 Hz,

CH₃CH₂), 1.36 (t, 18H, J = 7.2 Hz, POCH₂CH₃), 0.83 (t, 3H,

J = 7.5 Hz, CH₃CH₂); ¹³C NMR d: 164.41, 164.37, 71.4, 70.0,

62.94, 62.87, 43.5, 40.0, 36.0, 34.7, 23.1, 16.36, 16.30, 7.8.

1,1,1-Tris[(carbamoyl)methyl]propane (20). In an open ﬂask

ester 19 (5.73 g, 13 mmol) was dissolved in a cold mixture of

MeOH (60 mL) and liquid ammonia (100 mL). The mixture

was allowed to warm up to room temperature and left for 72 h.

After solvent evaporation the crude product was puriﬁed by

column chromatography (SiO₂, CH₂Cl₂–EtOH–NH₃

=

65 : 32 : 3) to give pure 20. Yield 2.77 g (69%); mp 107 1C;

FAB-MS: m/z 306.2 ([M + H]⁺, calc. 306.2); ¹H NMR d: 3.78

(s, 6H, OCH₂CO), 3.36 (s, 6H, CCH₂O), 1.40 (q, 2H, J = 7.6

Hz, CH₃CH₂), 0.81 (t, 3H, J=7.6 Hz, CH₃CH₂); ¹³C NMR d:

174.4, 71.2, 70.2, 42.6, 22.4, 7.4.

1,1,1-Tris[(2-aminoethoxymethyl]propane (21). To a suspen-

sion of 20 (1.00 g, 3.27 mmol) in dry THF (100 mL) was added

1 M BH₃(60 mL, 60 mmol) and the mixture was reﬂuxed for

48 h. After acidiﬁcation at room temperature with 32% HCl to

pH 1, the solvent was evaporated with a rotavapor. The

remaining solid was suspended in a 25% aqueous NH₃solu-

tion and extracted with CHCl₃(4 ꢁ 20 mL). The organic layer

was dried with MgSO₄and evaporation of the solvent gave

crude 21, which was used in the next step without further

puriﬁcation. Yield 840 mg (98%).

Cosan-containing CMPO tripodand 26. CMPO tripodand 9

(95 mg, 0.115 mmol) was dissolved under stirring in DME (5

mL) in a two necked 25 mL Schlenk ﬂask, equipped with a

nitrogen inlet and a rubber septum. Then solid NaH (12 mg,

0.5 mmol) was added in one portion and the content of the

ﬂask was stirred for 2 h. A solution of COSAN-dioxane 25a

(47 mg, 0.115 mmol) in toluene (4.5 mL) was dropwise added

with a syringe through the septum, and the reaction mixture

was stirred at ambient temperature for 7 days. 50% Aqueous

ethanol (1 mL) was added to the reaction mixture followed by

three drops of acetic acid (3 M), whereupon the solvents were

evaporated. The residue was dissolved in diethyl ether and

treated with 3 M HCl (3 ꢁ 10 mL). The organic phase was

separated and the solvents evaporated. The crude product was

puriﬁed by column chromatography (SiO₂, CH₃CN–CH₂Cl₂

= 1 : 3). The fraction corresponding to R_f0.07 on TLC

(Silufol^s, CH₃CN–CH₂Cl₂= 1 : 3) was collected to give 26

as an orange semi-solid material. Yield 30 mg (21%). ¹¹B

NMR (128 MHz, acetone-d₆, 25 1C, BF₃ꢃ Et₂O) d: 23.4 (s, 1B,

B8), 4.4 (d, ¹J(B,H) = 125 Hz, 1B, B8⁰), 0.4 (d, ¹J(B,H) = 129

Hz, 1B, B10⁰), ꢂ2.5 (d, ¹J(B,H) = 142 Hz, 1B, B10), ꢂ4.1 (d,

¹J(B,H) = 153 Hz, 2B, B4⁰,7⁰), ꢂ7.5 (2d, overlap, 6B,

Chloroacetamido tripodand 22. To a cold (0 1C) CH₂Cl₂

solution (50 mL) of 21 (840 mg, 3.19 mmol) were added dry

K₂CO₃(4.41 g, 32 mmol) and 6-chlorohexanoyl chloride (5.41

g, 32 mmol). Subsequently, H₂O (0.58 g, 32 mmol) was added

in a few small portions over 1 h. The reaction mixture was

allowed to warm up to room temperature and left for 24 h.

After ﬁltration of solid material, evaporation of the solvent

resulted in crude 22, which was used in the next step without

puriﬁcation. Yield 1.53 g (98%). ¹H NMR d: 4.07 (s, 6H,

COCH₂Cl), 3.51 (m, 12H, OCH₂CH₂N), 3.35 (s, 6H,

CCH₂O), 1.44 (q, 2H, J = 7.5 Hz, CH₃CH₂), 0.87 (t, 3H,

J = 7.5 Hz, CH₃CH₂).

1,1,1-Tris[(diphenylcarbamoylmethylphosphine oxide N-

ethoxy)methyl]propane (23). In an open ﬂask compound 22

(296 mg, 0.60 mmol) was dissolved in a small amount of ethyl

diphenylphosphinite (0.45 mL, 2.08 mmol), while the tempera-

ture was gradually increased from 100 to 150 1C. Subse-

quently, the mixture was stirred for 1 h at 150 1C. After

cooling of the reaction mixture, diisopropyl ether was added

and the mixture left stirring overnight. The organic solution

1

B4,7,9,12, 9⁰,12⁰), ꢂ17.3 (d, J(B,H) = 131 Hz, 2B, B5⁰,11⁰),

1

ꢂ20.3 (d, J(B,H) = 144 Hz, 2B, B5,11), ꢂ21.7 (d, overlap,

1B, B6⁰), ꢂ28.1 (d, ¹J(B,H) = 139 Hz, 1B, B6); ¹H NMR

(acetone-d₆) d: 7.87–7.91 and 7.28–7.59 (4m, 12 + 18H,

PC₆H₅), 4.22–4.25 (m, 6H, OCH₂CH₂O, CH₂O), 3.79, 4.06

(2s, 4H, CH_carborane), 3.53–3.71 (m, 18H, CH₂O, CH₂P,

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CH₂NH), 3.27–3.29 (m, 2H, CH₂NH), 1.27–1.30 (m, 6H,

CH₂NHC(O)C), 6.23 (s, 1H, CH₂CONHC), 4.08, 4.21 (2s,

4H, CH_carborane), 3.82–3.95 (m, 6H, CCH₂OCH₂, CH₂O), 3.71

(t, 4H, J = 5.6 Hz, OCH₂), 3.59 (t, 2H, J = 5.0 Hz, OCH₂),

3.44 (t, 4H, J = 5.1 Hz, OCH₂), 3.31–3.32 (m, 6H, OCH₂),

3.28 (m, 12H, C(O)CH₂PO, OCH₂CH₂CH₂N), 2.13 (t, 2H,

CH₂).

Cosan-containing CMP tripodand 27. Compound 27 was

prepared analogously to the previous procedure, but without

addition of NaH in the ﬁrst step. A solution of CMP tripo-

dand 10 (48 mg, 0.0471 mmol) in DME (5 mL) was reacted

with a solution of COSAN-dioxane 25a (23 mg, 0.506 mmol)

in toluene at ambient temperature for 6 days. After evapora-

tion of the solvent the resulting residue was puriﬁed by ﬂash

chromatography (SiO₂, CH₃CN–CH₂Cl₂= 1 : 4). The frac-

tion corresponding to R_F0.24 on TLC (Silufol^s,

CH₃CN–CH₂Cl₂= 1 : 6) was collected to give 27 as an orange

semi-solid material. Yield 40 mg (58%). ¹¹B NMR (128 MHz,

acetone-d₆, 25 1C, BF₃ꢃ Et₂O) d: 23.8 (s, 1B, B8), 4.5 (d,

J

= 7.4 Hz, OCH₂C₃H₆CH₂CO), 1.79–1.91 (m, 8H,

OCH₂CH₂CH₂N, OCH₂C₃H₆CH₂CO), 1.70–1.72, 1.46–1.50

(m, 6H, OCH₂C₃H₆CH₂CO).

Cosan-containing CMP tripodand 29. A stirred solution of

[8-(HO(CH₂CH₂O)-COSAN]Me₃NH 25b (39 mg, 0.08 mmol)

in THF (5 mL) was treated with NaH (12 mg, 0.5 mmol). The

slurry was stirred for 4 h and then evaporated on a vacuum

line almost to dryness to remove the solvent and the trimethyl-

amine. Then freshly distilled THF was injected (5 mL). A

solution of 16 (78 mg, 0.08 mmol) in THF (5 mL) was

dropwise added with a syringe through a septum during 2 h,

and the reaction mixture was stirred at 60 1C for 72 h. After

cooling down, the reaction was quenched by addition of 50%

aqueous ethanol (1 mL), followed by three drops of acetic acid

(3 M). Silica gel (2 g) was added and the solvents were

evaporated. The silica gel containing crude product was

poured on top of a chromatographic column and puriﬁed by

column chromatography (SiO₂, CH₃CN–CH₂Cl₂= 1 : 3 fol-

lowed by CH₃CN–MeOH = 1 : 1). The fraction corresponding

to R_F0.01 on TLC (Silufol^s, CH₃CN–CH₂Cl₂= 1 : 3) was

collected to give 29 as an orange semi-solid material. Yield 49

mg (44%). ¹¹B NMR (128 MHz, acetone-d₆, 25 1C,

BF₃ꢃ Et₂O) d: 23.3 (s, 1B, B8), 4.6 (d, ¹J(B,H) = 125 Hz,

1B, B8⁰), 0.5 (d, ¹J(B,H) = 129 Hz, 1B, B10⁰), ꢂ2.6 (d, ¹J(B,H)

= 142 Hz, 1B, B10), ꢂ4.3 (d, ¹J(B,H) = 153 Hz, 2B, B4⁰,7⁰),

ꢂ7.2 to ꢂ8.1 (2d, overlap, 6B, B4,7,9,12, 9⁰,12⁰), ꢂ17.3 (d,

¹J(B,H) = 131 Hz, 2B, B5⁰,11⁰), ꢂ20.3 (d, ¹J(B,H) = 144 Hz,

1

¹J(B,H) = 125 Hz, 1B, B8⁰), 0.4 (d, J(B,H) = 129 Hz, 1B,

B10⁰), ꢂ2.5 (d, ¹J(B,H) = 142 Hz, 1B, B10), ꢂ4.1 (d, ¹J(B,H)

= 153 Hz, 2B, B4⁰,7⁰), ꢂ7.3 (2d, overlap, 6B, B4,7,9,12,

1

9⁰,12⁰), ꢂ17.3 (d, J(B,H) = 131 Hz, 2B, B5⁰,11⁰), ꢂ20.3 (d,

¹J(B,H) = 144 Hz, 2B, B5,11), ꢂ21.7 (d, overlap, 1B, B6⁰),

ꢂ28.1 (d, ¹J(B,H) = 139 Hz, 1B, B6); ¹H NMR (acetone-d₆) d:

4.07–4.17 (m, 18H, OCH₂CH₂O, OCH₂), 3.86, 4.05 (4H,

CH_carborane), 3.45–3.64 (m, 6H, OCH₂), 3.41–3.65 (m, 14H,

CH₂NH, CCH₂O, CH₂NH), 2.95 (br d, 6H, CH₂P), 1.82–1.96

(m, 6H, CH₂), 1.29–1.31 (m, 18H, CH₃).

Cosan-containing CMPO tripodand 28. A stirred solution of

[8-(HO(CH₂CH₂O)-COSAN]Me₃NH 25b (22 mg, 0.045

mmol) in THF (5 mL) was treated with NaH (6 mg, 0.25

mmol). The slurry was stirred for 4 h and then the solvent and

the trimethylamine were evaporated on a vacuum line almost

to dryness. Subsequently, freshly distilled THF was injected (5

mL). A solution of 15 (52 mg, 0.045 mmol) in THF (5 mL) was

dropwise added with a syringe through a septum during 2 h,

and the reaction mixture was stirred at 50 1C for 24 h. NaH (6

mg, 0.25 mmol) was added and the reaction mixture was

stirred at 50 1C for an additional 48 h. After cooling down,

the reaction mixture was quenched by addition of 50% aqu-

eous ethanol (1 mL) followed by three drops of acetic acid (3

M), whereupon the solvents were evaporated. The residue was

dissolved in ethyl acetate and treated with 3 M HCl (3 ꢁ 10

mL), cold (0 1C) 5% Na₂CO₃solutions (3 ꢁ 10 mL), and with

brine (4 ꢁ 10 mL). After evaporation of the solvent, the crude

product was puriﬁed by column chromatography (SiO₂,

CH₃CN–CH₂Cl₂= 1 : 3 followed by CH₃CN–MeOH =

1 : 1). The fraction corresponding to R_F0.03 on TLC (Silu-

fol^s, CH₃CN–CH₂Cl₂= 1 : 3) was collected, the solvent

evaporated, dried in vacuum, the residue redissolved in dry

CH₃CN, ﬁltered, and the solvent evaporated to give 28 as an

orange semi-solid material. Yield 45 mg (63%). ¹¹B NMR (128

MHz, acetone-d₆, 25 1C, BF₃ꢃ Et₂O) d: 23.3 (s, 1B, B8), 4.5 (d,

1

2B, B5,11), ꢂ21.7 (d, overlap, 1B, B6⁰), ꢂ28.4 (d, J(B,H) =

139 Hz, 1B, B6); ¹H NMR d: 7.61 (br s, 3H, CH₂NHCO), 7.90

(s, 1H, CH₂CONHC), 4.15 (m, 12H, POCH₂CH₃), 3.80, 3.89

(2s, 4H, CH_carborane), 3.74 (s, 6H, CCH₂OCH₂), 3.61–3.80 (m,

4H, OCH₂), 3.32–3.39 (m, 6H, OCH₂CH₂CH₂N), 3.32–3.39

(m, 4H, OCH₂), 3.02 (d, 6H, J = 18 Hz, COCH₂PO), 2.24 (t,

2H, J = 5.2 Hz, OCH₂C₃H₆CH₂CO), 1.45–1.82 (m, 12 H,

OCH₂CH₂CH₂N, OCH₂C₃H₆CH₂CO), 1.31 (t, 18H, J = 7.2

Hz, POCH₂CH₃).

Picrate extractions

Solutions. The 10–4 M salt stock solutions were prepared by

dissolving the required amounts of the appropriate metal

ꢂ

nitrate Mⁿ⁺(NO₃

)

and LiPic in 10^ꢂ3M HNO₃adjusting

n

the total volume of the solution to 100 mL using volumetric

glassware. The pH of the solutions was close to pH 3, and

adjusted to pH 3 by adding small amounts of LiOH. The 10^ꢂ3

M stock solutions of the ligands were prepared by dissolving

the appropriate amount of ligands in 20 mL of CH₂Cl₂.

1

¹J(B,H) = 125 Hz, 1B, B8⁰), 0.4 (d, J(B,H) = 129 Hz, 1B,

B10⁰), ꢂ2.5 (d, ¹J(B,H) = 142 Hz, 1B, B10), ꢂ4.3 (d, ¹J(B,H)

= 153 Hz, 2B, B4⁰,7⁰), ꢂ7.3 to ꢂ8.0 (2d, overlap, 6B,

Procedure. Equal volumes (1.0 mL) of the organic and the

aqueous solutions were transferred into a stoppered glass vial

and stirred at ambient temperatures (about 23 1C) for 17 h.

The two phases were separated by centrifugation (1600 rpm

for 10 min). The concentration of picrate ion in the aqueous

and organic phase was determined spectrophotometrically

1

B4,7,9,12, 9⁰,12⁰), ꢂ17.2 (d, J(B,H) = 131 Hz, 2B, B5⁰,11⁰),

1

ꢂ20.4 (d, J(B,H) = 144 Hz, 2B, B5,11), ꢂ21.7 (d, overlap,

1

1B, B6⁰), ꢂ28.4 (d, J(B,H) = 139 Hz, 1B, B6); H NMR d:

7.71–7.85 (m, 12H, PC₆H₅), 7.48–7.54 (m, 6H, PC₆H₅),

7.21–7.28 (m, 12H, PC₆H₅), 7.03 (t, 3H, J = 5.5 Hz,

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(l_max= 355 nm). Each measurement was repeated three times.

Blank experiments showed that no picrate extraction occurred

in the absence of ionophore. The percentage of the cation

extracted into the organic phase (%E = E ꢁ 100%), deﬁned

as the ratio of the activity in the organic phase (A_o) and the

total activity in both the organic and the aqueous phase (A_w),

is expressed by the following equation:

where R, T and F are the gas constant, absolute temperature

and the Faraday constant, respectively. The charge of the

primary ion, i, is indicated as z_iand the measured potentials

for primary and interfering ions are put as E⁰_iand E_j⁰,

respectively.

Determination of the stability constants. Experiments were

carried out according to the procedure described in litera-

ture.¹¹Two sets of membranes were prepared: membranes

with and without ionophore. A series of 7 mm i.d. membrane

discs were cut from the parent membrane, and these disks were

conditioned over 2–3 days in appropriate salt solutions (10^ꢂ1

M NaCl, 10^ꢂ2M CuCl₂, 10^ꢂ2M CdCl₂, 5 ꢁ 10^ꢂ3M PbCl₂,

10^ꢂ3M UO₂(NO₃)₂/10^ꢂ3M NaCl (pH = 4)). After drying of

the individual membranes, the sandwich membrane was made

by attaching of the membrane with ionophore to the mem-

brane without ionophore. The segmented membrane was than

mounted into a Philips electrode body (membrane with iono-

phore faced the sample solution) and immediately immersed

into an appropriate salt solution (identical as for conditioning

of the membrane). The potential was recorded as the mean of

the last minute of a 10 min measurement period in the

appropriate salt solution. The potential of the electrodes with

sandwich membranes remained free of diﬀusion-induced drifts

for 20–50 min, depending on the ionophore incorporated

within the membrane and the ion measured. Membrane

potential values DEMF were calculated by subtracting the cell

potential for a membrane without ionophore from that of the

%E = (A_o/(A_o+ A_w)) ꢁ 100%

Potentiometric measurements

Reagents. The salts and membrane components potas-

sium tetrakis[3,4-bis(triﬂuoromethyl)phenyl]borate (KTFPB),

o-nitrophenyl octyl ether (o-NPOE), high molecular weight poly

(vinyl chloride) (PVC) and tetrahydrofuran (THF, distilled

prior to use) and all salts were purchased from Fluka (Ron-

konkoma, NY). Aqueous solutions were obtained by dissol-

ving the appropriate salts in Nanopure puriﬁed distilled water.

Membrane preparation. The polymeric membranes used for

the determination of the stability constants contained iono-

phore (20 mmol/kg), KTFPB (2 mmol kg^ꢂ1) in PVC/o-NPOE

(1 : 2 by weight) polymeric matrix (unless otherwise indicated

in the text). The membrane components (total 140 mg) were

dissolved in freshly distilled THF (1.4 mL). The solution was

placed in a glass ring (22 mm i.d.) mounted over a glass plate

and than covered with another glass plate to slow down the

solvent evaporation. After 24 h, the resulting membrane was

peeled from the glass plate and discs of 7 mm diameter were

cut out. The procedure for the preparation of the polymeric

membranes evaluated for the potentiometric ion response was

similar to that described above. The total amount of mem-

brane components was 200 mg and the membranes consisted

of 1 wt% of ionophore, 30 mol% of KTFPB and PVC/o-

NPOE (1 : 2 by weight).

sandwich membrane. The formation constant, b_IL, was cal-

culated from the following equation:

n

ꢂ

ꢃ_ꢂn

ꢂ

ꢃ

n

L_Tꢂ R^ꢂ_T

z_i

z_iF

RT

b_IL

¼

exp

DEMF

n

where: n is the complex stoichiometry, L_Tand R_Tare the

concentrations of ionophore and ionic site additives in the

membrane, respectively.

Potentiometric response to cations and selectivity measure-

ments. Membrane discs were mounted in conventional ISE

electrode bodies (Type IS 561; Philips, Eindhoven, The Nether-

lands) for electromotive force (EMF) measurements. All mea-

surements were made at ambient temperature (22 ꢄ 1 1C)

using a galvanic cell of the following type: Ag|AgCl_(s)|3 M

KCl|bridge electrolyte|sample|ion-selective membrane|inner

ﬁlling solution|AgCl_(s)/Ag. The bridge electrolyte consisted

of 1 M lithium acetate. The inner ﬁlling solution of the ISEs

was a 0.01 M NaCl solution. The EMF values were measured

using a custom made 16-channel electrode monitor. Details of

this equipment have been described previously.²⁹

Extractions

Liquid–liquid extractions of europium and americium by

CMP(O) tripodands 3, 4, 11–14, 23 and 24. Organic and

aqueous phases (V_org= V_aq= 200 mL) were mixed in 2 mL

Eppendorf micro-tubes, thermostated at (25 ꢄ 0.5) 1C and

shaken for 60 min with a vortex IKA device (Vibrax VXR).

Tubes were centrifuged and 40 mL of each phase were diluted

either in 560 mL of 1,1,2,2-tetrachloroethane or 1-octanol for

the organic samples, or in 560 mL of 1 or 3 M nitric acid for the

aqueous samples. 550 mL of each sample were used for radio-

metric (gamma) analyses. All extractions were performed in

duplicate. The accuracy of the D values of Table 2 is about

20%. The D values (10^ꢂ2and lower) in Table 3, when

1-octanol is used as a solvent, were determined with a surpris-

ingly high accuracy (about 10%). The reason is that the

organic phase, although of low activity, cannot be contami-

nated when sampling it.

The performance of the electrodes was examined by mea-

suring the EMF for solutions of the examined cations over the

concentration range of 10^ꢂ7–10^ꢂ1M. Activity coeﬃcients were

calculated according to the Debye–Huckel approximation.³⁰

¨

Potentiometric selectivity coeﬃcients were determined by the

separate solution method (SSM) according to the modiﬁcation

of the method described in literature.¹³Selectivity coeﬃcient

pot

I,J

K

values were obtained from adequate, unbiased E⁰mea-

The acidity of the initial and ﬁnal aqueous solutions was

determined by potentiometric titration on 100 mL samples,

using a METROHM 751 GPD Titrino device and a [NaOH]

= 0.1 mol L^ꢂ1solution.

surements for each ion, according to the equation:

ꢀ

ꢁ

z_iF

RT

pot

i;j

K

¼ exp

ðE_j⁰ꢂ E_i⁰Þ

ꢀc

This journal is the Royal Society of Chemistry and the Centre National de la Recherche Scientiﬁque 2006

New J. Chem., 2006, 30, 1480–1492 | 1491

View Article Online

Liquid–liquid extractions of europium and americium by the

COSAN-containing samples. All extraction experiments were

executed in polypropylene test tubes at 25 ꢄ 0.5 1C. The

volume of both phases was 1 mL. The samples were shaken for

1 h on a rotating apparatus. The organic and aqueous phases

were separated by centrifugation. All reagents and solvents

used were of AR purity. ¹⁵²Eu and ²⁴¹Am tracers (radio-

chemical purity) were used for the measurement of the

Eu/Am distribution. Their g activity was measured by a single

channel analyzer with a NaI-Tl well-type detector. All extrac-

tions were performed in duplicate. In the range of 0.1–10 the

error in the D values is about 5%, while in the ranges of

0.01–0.1 and 10–100 the error is about 10%. For higher and

lower D values the error may increase to 30–40%.

Schmidt, V. Bohmer, V. Host, J.-F. Desreux and J.-F. Dozol,

¨

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Extractions of Am³⁺and Eu³⁺with CMP(O) tripodand-

containing magnetic particles. In aqueous phase was prepared

at varying HNO₃concentrations (0.01–3 M). Europium, as

radioisotope ¹⁵²Eu, and americium, as radioisotope ²⁴¹Am,

were added at an activity around 1500 kBq dm^ꢂ3, which

corresponds approximately to a concentration of 5 ꢁ 10^ꢂ8

M for Am³⁺and 1.5 ꢁ 10^ꢂ9M for Eu³⁺. 10 mL of the

aqueous phase was shaken with particles (300 mg) for 1 h and

than separated by magnetic techniques. The initial and ﬁnal

concentrations of the lanthanides and actinides in the aqueous

phases were determined using a single-channel g analyzer with

a NaI (Tl) well detector. All experiments were carried out in

duplicate. The error in the D values is about 10%.

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1127; (b) E. Bakker, P. Buhlman and E. Pretsch, Chem. Rev., 1997,

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rski, D. Wojciechowska, M. M. Reinoso-

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sek, J. Ba

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ca, I. Cısarova, V. Bohmer, C.

´ ´ ´

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Danila, M. M. Reinoso-Garcıa, W. Verboom, D. N. Reinhoudt,

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We gratefully acknowledge the ﬁnancial support from the

EEC (contracts FIKW-CT-2000-00088 and F16W-CT-2003-

508854). The part of this work related to the potentiometric

studies was ﬁnancially supported by the Warsaw University of

Technology.

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1492 | New J. Chem., 2006, 30, 1480–1492

Article Doi

CMP(O) tripodands: Synthesis, potentiometric studies and extractions

DOI: 10.1039/b600412a

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Article abstract of DOI:10.1039/b600412a

Full text of DOI:10.1039/b600412a

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