Synthesis of novel uranyl salophene derivatives and evaluation as sensing molecules in chemically modified field effect transistors (CHEMFETs)

Article abstract of DOI:10.1039/a810019e

Several anion receptors have been synthesized based on the uranyl salophene moiety. The binding selectivity of the receptors can be influenced by substituents near the uranyl binding site of the receptor, which change the electron density of the uranyl ce

Full text of DOI:10.1039/a810019e

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Synthesis of novel uranyl salophene derivatives and evaluation as
sensing molecules in chemically modified field effect transistors
(CHEMFETs)
Martijn M. G. Antonisse,† Bianca H. M. Snellink-Ruël, Alina C. Ion,‡ Johan F. J. Engbersen
and David N. Reinhoudt*
Department of Supramolecular Chemistry and Technology, MESA Research Institute,
University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
Received (in Cambridge) 24th December 1998, Accepted 25th March 1999
Several anion receptors have been synthesized based on the uranyl salophene moiety. The binding selectivity of the
receptors can be influenced by substituents near the uranyl binding site of the receptor, which change the electron
density of the uranyl center, the lipophilicity of the binding cleft, or provide sites for hydrogen bonding. The
differences in binding selectivity are reflected in the selectivity of potentiometric sensors (chemically modified field
effect transistors, CHEMFETs) developed with these receptors. The use of a uranyl salophene derivative with phenyl
substituents near the binding site yields acetate selective sensors with selectivity over much more lipophilic anions like
Pot
AcO,j
ClϪ and BrϪ (log K
= Ϫ1.2). Lipophilic N-octanamido substituents near the uranyl center provide FϪ selective
CHEMFETs. The presence of urea moieties in the proximity of the binding site results in an even stronger
FϪ binding receptor which yields CHEMFETs which can detect FϪ even in the presence of a 150-fold
Pot
F,SCN
excess of the very lipophilic SCNϪ anion (log K
= Ϫ2.2).
substituents near the uranyl binding center, substituents that
affect anion binding by electronic or steric effects have also been
included.
Introduction
The selective detection of ions requires a chemical recognition
process involving the specific interaction with a receptor mol-
ecule. Although for cations many receptors have been syn-
thesized and used in sensing devices, the number of receptors
that have been developed for selective anion binding is only
limited.1 In previous papers we have reported that neutral
uranyl salophene derivatives show anion binding properties due
to the Lewis acidic character of the uranyl center.2,3 In order to
make this class of anion receptors applicable as receptor mol-
ecules in polymeric membrane sensors like ion-selective elec-
trodes (ISEs) and chemically modified field effect transistors
(CHEMFETs), the salophene moiety has been modified with
lipophilic aliphatic substituents.4 The lipophilic uranyl salo-
Results and discussion
Synthesis and properties of lipophilic uranyl salophene derivatives
The lipophilic uranyl salophene derivatives are easily syn-
thesized by condensation of 1,2-dialkoxy-4,5-diaminobenzene
(2) with salicylaldehyde 1a–i in methanol and subsequent add-
ition of uranyl acetate (Scheme 1).4 By using salicylaldehyde
Ϫ
phene derivative 3a shows a strong interaction with the H2PO4
anion, and this receptor could be successfully applied in
CHEMFETs with selectivity towards this hydrophilic anion.4,5
By introduction of substituents at the salophene moiety in close
proximity of the anion coordination site of the uranyl center,
the binding selectivity of uranyl salophene derivatives can be
influenced. For example, the presence of the methoxy-
substituents in uranyl salophene derivative 3b results in sensors
with an improved H2PO4Ϫ sensitivity.5 When the H2PO4Ϫ anion
is bound with one of the oxygen atoms to the uranyl center a
hydrogen bond can be donated to the methoxy group and con-
sequently the binding strength is increased. On the other hand,
the presence of acetamido groups in derivative 3c reduce the
Ϫ
H2PO4 binding strength, but these hydrogen bond donating
substituents induced strong binding for the FϪ anion.4,6
This paper describes the synthesis of various new lipophilic
uranyl salophene derivatives and their evaluation as sensing
molecules in ISE and CHEMFET membranes. Besides the
incorporation of hydrogen bond donating and accepting
† Present address: DSM-Resins, Zwolle, The Netherlands.
‡ On leave from the University ‘Politechnica’ of Bucharest, Bucharest,
Romania.
Scheme 1
J. Chem. Soc., Perkin Trans. 2, 1999, 1211–1218
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derivatives with the desired substituent at the 3-position, this
substituent is introduced in the uranyl salophene receptor in
close proximity to the uranyl center. For example the use of 3-
fluorosalicylaldehyde (1d), results in the formation of derivative
3d in 70% yield. The presence of the electron-withdrawing
fluoro substituents in this compound lowers the electron dens-
ity of the uranyl center resulting in a higher electrophilicity of
the center. The opposite effect is obtained by the introduction
of methoxy substituents as these are present in the previously
synthesized methoxy-substituted derivative 3b.
trum which is present at 1608 cmϪ1 instead of 1685 cmϪ1 (as for
1g).9
The amido substituents of uranyl salophene 6 are linked via a
polyether bridge. This salophene derivative was obtained by
cyclization of dialdehyde 5 with diamine 2 in the presence of
Ba(OTf)2 as a template, followed by addition of UO2(OAc)2ؒ
1
2H2O (Scheme 3). In contrast to 3g, the H NMR spectra of
In derivative 3e the phenyl substituents form a lipophilic cleft
and a coplanar positioning of these substituents allows π–π
interactions with aromatic guests.7 The synthesis of 3e starts
with 2-hydroxy-1,1Ј-biphenyl-3-carbaldehyde (1e) which was
obtained from 2-hydroxybiphenyl by first protecting the
hydroxy moiety with a methoxy methyl ether group yielding 4,
followed by formylation with DMF and deprotection with HCl
(Scheme 2). The aldehyde 1e was reacted with 2 to give 3e in
Scheme 3
this compound do not show any indication of the formation
of dimers. The short bridge between the amido substituents
reduces the flexibility of these substituents and no inter- or
intramolecular interactions can be formed between the amido
carbonyl and the uranyl center.
Because of the successful application of derivative 3c in the
development of FϪ selective CHEMFETs, the lipophilicity of
this derivative was further enhanced by introducing octanoic
acid amido substituents (3h, 7) instead of the acetamido
moieties. Uranyl salene 7 was prepared by reaction of 1h with
cis-1,2-diaminocyclohexane. Although compound 7 lacks the
Scheme 2
69% yield. Derivative 3f was obtained from 3,5-di-tert-
butylsalicylaldehyde (1f) in 53% yield and also in this com-
pound the binding cleft is rather apolar and small due to the
presence of tert-butyl substituents.
In derivative 3g the –OCH2CONH– moieties can contribute
to the binding of dihydrogen phosphate anions by hydrogen
donation from the amide hydrogen atoms and hydrogen bond
acceptance from one ether oxygen atom. Such a binding mode
was previously shown in the X-ray crystal structure of the
phosphate complex of the corresponding salophene derivative
lacking the dodecyl substituents.2 The 1H NMR spectrum of 3g
in DMSO-d6 has the appearance that is normally expected for
uranyl salophene derivatives, with a singlet signal of the imine
hydrogen atom at 9.62 ppm. However, the spectrum of 3g in
CDCl3 shows two singlets at 9.34 and 9.17 ppm, and also
double signals of the amide hydrogen atoms (at 12.78 and 10.54
ppm) and the tolyl methyl hydrogen atoms (at 1.98 and 1.65
ppm) are clearly visible, similar to the signals observed for
derivative 3c.8 This is probably due to the formation of dimers
of 3g, as is known from the X-ray crystal structure of the cor-
responding non-lipophilic derivative.2 In this structure one
amido oxygen atom is coordinated to the uranyl center of a
second uranyl salophene molecule and vice versa. No change in
NMR spectrum is observed upon dilution, indicating a high
association constant. Alternatively, Corey–Pauling–Koltun
(CPK) models show that the asymmetry in molecule 3g can also
be caused by intramolecular coordination of one of the amido
carbonyl oxygens with the uranyl center. This is in contrast to
derivative 3c which can only form intermolecular interactions.
Coordination of the carbonyl oxygen of 3g to the uranyl center
lipophilic dodecyloxy substituents, the octanoic acid amido
substituents make this salene well soluble in for example chloro-
form. Like compound 3c, derivatives 3h and 7 also form dimers
1
and double signals are present in the H NMR spectra. Even
the methyl hydrogen atoms of the octanoyl group of 3h, which
are located at a large distance from the coordinating carbonyl
moiety, show a pair of triplets at 0.71 and 0.53 ppm.
In uranyl salophene derivative 3i the presence of the urea
moieties results in an increased number of donating hydrogen
atoms in this receptor. The N-propylurea substituted salicyl-
aldehyde derivative was obtained by first treatment of salicyl-
aldehyde derivative 1c with hydrazine (Scheme 4). In this
procedure in one step the carbonyl moieties are protected and
the acetyl moieties are removed by trans-amidation. Treatment
with propyl isocyanate and HCl results in salicylaldehyde
derivative 1i.
is also reflected in a shift of the C᎐O vibration in the IR spec-
᎐
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Fig. 1 SSM selectivity coefficients of ISEs with uranyl salophene derivatives 3a–i, 6, or 7 (1 wt% and 20 mol% TOAB in NPOE plasticized PVC
2Ϫ
membranes) or with 0.1 wt% of TOAB (Hofmeister series). 1: ClO4Ϫ, 2: SCNϪ, 3: SalϪ, 4: BrϪ, 5: ClϪ, 6: FϪ, 7: AcOϪ, 8: H2PO4Ϫ, 9: SO4
.
comparison also the data of ISEs with salophene derivatives
3a–c and the Hofmeister selectivity sequence obtained with
ISE membranes with only TOAB are included. Several of the
salophene receptors induce a different sensor selectivity. The
ISEs with uranyl salophene derivatives 3c–g all show increased
selectivity towards the FϪ anion and among the lipophilic
anions enhanced selectivity is observed towards the small SCNϪ
anion with receptors 3e and 3f. The electron-withdrawing
fluoro substituents of 3d induce a decrease in sensor sensitivity
Ϫ
towards NO3 . Consequently most SSM selectivity values are
shifted to more positive values compared to receptors 3a and
3b. Furthermore, the apolar cleft formed by the phenyl sub-
stituents of salophene 3e results in selectivity for AcOϪ over
Ϫ
NO3 , which is a remarkable result as the acetate ion is a hydro-
Ϫ
2Ϫ
philic anion which is close to H2PO4 and SO4 in the
Hofmeister series (see Fig. 1, TOAB). Remarkably, membranes
with salophene 3g do not show any preference for H2PO4Ϫ and
an equal sensitivity is obtained as for SO42Ϫ. This latter result
was not expected on the basis of the previously determined
association constants in DMSO-d6 for salene derivatives related
to 3g (and 3b) based on diaminocyclohexane (Ka = 8.0 × 103
MϪ1 and 5.1 × 102 MϪ1, respectively).2 Dimerization of 3g, as
was observed in media like CDCl3 and in the solid state, might
reduce the binding properties of this receptor in the ion-
selective membrane. A strong interaction between the amido
oxygen atom and the uranyl center then competes with the
interaction of the uranyl salophene with the H2PO4Ϫ anion.
Compared to the FϪ binding uranyl salophene 3c, the related
but more lipophilic compounds 3h and 7 give an even better
Ϫ
Scheme 4
selectivity over other hydrophilic anions and ClO4 , although
the lipophilic SCNϪ still severely interferes at equal or higher
concentrations. By increasing the number of hydrogen bond
donating sites, as in 3i, even selectivity over this generally
strongly interfering anion is obtained. Compared to the Hof-
meister selectivities the presence of receptor 3i in the membrane
results in an increase in the FϪ selectivity over SCNϪ with a
factor of 105.
Evaluation of the receptor properties in ion-selective membranes
The applicability of the novel lipophilic uranyl salophene
derivatives in potentiometric sensor devices was first studied in
ion-selective electrodes. For this purpose plasticized poly(vinyl
chloride) (PVC) membranes were made containing 1 mg of the
receptor, 33 mg of PVC, 66 mg of o-nitrophenyl n-octyl ether
(NPOE) and 20 mol% (with respect to the receptor) of tetra-
octylammonium bromide (TOAB). All compounds, with the
exception of macrocycle 6, are well soluble in the membrane at
this concentration with the result that clear, homogeneous,
orange membranes were formed. The sensor selectivity of the
ISEs was evaluated according to the separate solution method
(SSM) at pH 6 (0.01 M 2-morpholinoethanesulfonic acid
(MES)) buffer and the results are depicted in Fig. 1. For
The various ISEs were also investigated for selectivity
towards anions that are only present in alkaline solutions,
2Ϫ
Ϫ
for example HPO4 and HCO3 . Equal selectivity towards
HPO42Ϫ, HCO3 , NO3 , ClϪ, and FϪ was observed for these
sensors at pH 8, with the exception of the ISEs based on the
uranyl sal(oph)enes 3h–i and 7 which show an increased select-
ivity towards FϪ even at this pH. Probably, at pH 8 for most
sensors the interference of OHϪ becomes dominant, thereby
masking any other preferential binding of the receptor.5
Ϫ
Ϫ
J. Chem. Soc., Perkin Trans. 2, 1999, 1211–1218
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Table 1 Sensor characteristics of acetate selective CHEMFETs with receptor 3e
a
log KPAoctO,j [slope mV decadeϪ1
]
Ϫ
Ϫ
2Ϫ
Receptor
Det. limitb
NO3
BrϪ
ClϪ
H2PO4
SO4
3e
Ϫ3.5 [Ϫ56]
Ϫ0.3 [Ϫ49]c
Ϫ1.2 [Ϫ49]
1.2 [Ϫ52]
Ϫ2.4 [Ϫ54]
Ϫ2.5 [Ϫ51]
a [j] = 0.1 M in 0.01 M MES, pH = 6.0. b log [AcOϪ] in 0.01 M MES, pH = 6.0. c [j] = 0.01 M in 0.01 M MES, pH = 6.0.
Table 2 Sensor characteristics of FϪ selecctive CHEMFETs with receptors 3h, 3i and 7
Pot
a
log K [slope mV decadeϪ1
]
F, j
Ϫ
Ϫ
Receptor
Det. limitb
SCNϪ
ClO4
NO3
BrϪ
ClϪ
3h
7
3i
Ϫ3.4 [Ϫ54]
Ϫ3.6 [Ϫ54]
Ϫ3.7 [Ϫ47]
>0
>0
Ϫ1.6 [Ϫ53]
Ϫ1.6 [Ϫ54]
Ϫ2.9 [Ϫ38]
Ϫ2.4 [Ϫ56]
Ϫ2.5 [Ϫ55]
Ϫ2.9 [Ϫ43]
Ϫ2.2 [Ϫ52]
Ϫ2.1 [Ϫ50]
Ϫ2.9 [Ϫ48]
Ϫ2.4 [Ϫ54]
Ϫ2.5 [Ϫ54]
Ϫ2.8 [Ϫ46]
Ϫ2.2 [Ϫ36]
a [j] = 0.1 M in 0.01 M MES, pH = 6.0. b log [FϪ] in 0.01 M MES, pH = 6.0. c [NO3Ϫ] = 0.01 M in 0.01 M MES, pH = 6.0.
Fig. 3 Fluoride response of a CHEMFET with receptor 3h in the
presence of 0.1 M NaNO3 (in 0.01 M MES, pH 6.0).
Fig. 2 Acetate response of a CHEMFET with receptor 3e in the
presence of 0.1 M NaH2PO4 (in 0.01 M MES, pH = 6.0).
Pot
lower selectivity for acetate over bromide (log K
= Ϫ0.6 vs.
AcO,Br
The performance of the uranyl salophene receptors in anion
sensing
Pot
Ϫ1.2) and over NO3Ϫ (log K
> 0 vs. Ϫ0.3) underlining the
AcO,NO3
beneficial interaction of the acetate anion with the phenyl sub-
stituents of 3e.
The SSM selectivity data obtained with ISEs show that the
novel uranyl salophene derivatives 3e, 3h, 3i, and 7 bind strongly
to hydrophilic anions and can result in sensors with selectivities
strongly deviating from the Hofmeister selectivity that is seen
for TOAB (Fig. 1). Therefore these receptors were applied
as the selector element in potentiometric CHEMFET micro-
sensors. To this end membrane solutions of the same com-
position as used for ISEs were cast on top of the gate of the
CHEMFETs and the response characteristics were evaluated.
It was found that ISEs with uranyl salophene receptor 3e
showed an increased selectivity towards acetate which can be
attributed to a favorable interaction between the phenyl sub-
stituents and the acetate methyl group. The acetate anion is very
hydrophilic and is located in the Hofmeister series between FϪ
Fluoride is a strong hydrogen bond acceptor and this makes
the ion very hydrophilic and difficult to extract into organic
media. Selective measurement of fluoride anions with poly-
meric membrane sensors therefore requires the presence of
extremely selective fluoride receptors in the membrane. The FϪ
selectivity observed for the uranyl salophene derivatives in sev-
eral of the developed ISEs indicates that the uranyl center has a
strong interaction with this anion and that hydrogen bond
donating sites can enhance the selectivity. Previously, well func-
tioning FϪ selective CHEMFETs have been developed4,6 based
on uranyl salophene derivative 3c. However, as already indi-
cated by the SSM selectivity data, the increased lipophilicity of
the amido binding site in 3h improves the CHEMFET charac-
Ϫ
Ϫ
and H2PO4 . CHEMFETs with 3e as anion receptor were
teristics (Table 2). The FϪ selectivity over NO3 and ClϪ is
Pot
F,Cl
investigated for their sensitivity and selectivity towards this
anion at pH 6 (Table 1). The sensors respond to acetate at con-
centrations ≥3 × 10Ϫ4 M with an almost Nernstian slope of Ϫ56
mV decadeϪ1. In spite of the high hydrophilicity of acetate,
selectivity for acetate is obtained over more lipophilic anions
increased (log K
= Ϫ2.4). As shown in Fig. 3 even in the pres-
ence of 0.1 M NO3Ϫ the sensors start to respond to FϪ with an
almost Nernstian slope of Ϫ56 mV decadeϪ1 at concentrations
≥8 × 10Ϫ4 M. Also in the presence of the other investigated
anions the response slopes are improved compared to the less
lipophilic receptor 3c. The lipophilic tert-butyl substituents
and the octanamido substituents improve the solubility of the
uranyl salophene, and also uranyl salene derivative 7, compris-
ing the cyclohexane unit, is well soluble in the ion-selective
membrane. This is reflected in the similar response slopes and
selectivities of CHEMFETs with 3c or 7.
Ϫ
Pot
AcO,j
Ϫ
like ClϪ, BrϪ, and NO3 (log K
= Ϫ1.2, Ϫ1.2, and Ϫ0.3,
respectively). Also over H2PO4 a 250-fold selectivity is
obtained (Fig. 2). Apparently, the phenyl substituents of 3e
which give a favorable interaction with the methyl group of the
Ϫ
acetate anion, unfavorably interact with the tetrahedral H2PO4
anion and consequently reduce the binding strength of the
H2PO4Ϫ anion with the uranyl center. The acetate over H2PO4
The CHEMFETs with N-propylurea substituted uranyl
salophene derivative 3i show an even higher FϪ selectivity. The
presence of 0.1 M of various anions which are more lipophilic
Ϫ
selectivity of sensors with 3e is reversed compared to CHEM-
FETs with salophene 3a. The latter sensors also show a much
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and the combined organic layers were washed with 5% NaOH,
water, and brine. After drying over Na2SO4, the solvent was
1
evaporated, yielding 2.3 g (90%) of 4 as a colorless oil. H
NMR δ 7.66 (dd, 2H, J = 8.1 Hz and 1.2 Hz, ArH), 7.56–7.33
(m, 7H, ArH), 7.25–7.20 (m, 1H, ArH), 5.21 (s, 2H,
OCH2OCH9), 3.49 (s, 3H, OCH2OCH3). 13C NMR δ 154.4 (s),
138.8 (s), 132.1 (s), 131.2 (d), 128.8 (d), 128.2 (d), 127.1 (d),
122.5 (d), 115.9 (d), 95.2 (t), 56.2 (q). MS-EI m/z 214.1 (Mϩ,
calcd. for C14H14O2 214.1).
2-Hydroxy-1,1Ј-biphenyl-3-carbaldehyde (1e)
To a solution of 1.0 g of 4 in 40 mL of dry Et2O, was added 1.1
eq n-BuLi (5.1 mL of a 1.6 M solution in hexane) at Ϫ78 ЊC.
The mixture was slowly warmed to room temperature and a
solution of 0.8 mL of DMF in 5 mL of Et2O was added and
after 2 h the solvent was evaporated. To remove the methoxy
methyl ether group the crude product was dissolved in 50 mL of
MeOH, and 6 g of NaCl and 5 g of H2SO4 were added to
produce in situ HCl. After stirring for 30 min 50 mL water was
added, and the solution was extracted with 50 mL Et2O. The
organic layer was washed with 0.1 M NaOH until the pH
reached 7, and dried over Na2SO4. Evaporation of the solvent
yielded 0.6 g (65%) of 1e. 1H NMR δ 10.30 (s, 1H, OH), 9.95 (s,
1H, CHO), 7.64 (m, 7H, ArH), 7.11 (t, 1H, J = 7.6 Hz, ArH).
Fig. 4 Fluoride response of a CHEMFET with receptor 3i in the
presence of 0.1 M NaBr (in 0.01 M MES, pH 6.0).
than FϪ has no influence on the detection limit of the sensors
and FϪ anions can be detected at concentrations ≥10Ϫ4 M (log
Pot
K
= Ϫ2.9, Table 2). Moreover, the use of this receptor results
F, j
in selectivity for FϪ over the lipophilic SCNϪ anion (log
Pot
F,SCN
K
= Ϫ2.2). This anion is generally strongly interfering in
SSM measurements with the uranyl salophene receptors as was
shown in Fig. 1. The high selectivities induced by 3i points to
a strong FϪ binding, and has the consequence that at high
FϪ concentrations coextraction takes place of FϪ anions with
sample cations (Donnan exclusion failure). This then results in
a decrease of the response slope and eventually even in a posi-
tive cation response slope. In Fig. 4 it is shown that indeed the
slope of the response starts to decrease at FϪ concentrations
above 0.05 M.
In summary, the present results illustrate that the use of the
uranyl salophene moiety opens various possibilities for the
development of anion receptors applicable in potentiometric
sensors. The salophene moiety can be modified with substitu-
ents that change the nature of the anion binding site, i.e. vary
the electron density of the uranyl binding center, vary the
lipophilicity and aromaticity of the binding cleft, or provide in
the availability of hydrogen bonding donating and accepting
sites. In this paper it is shown that besides an improvement of
the previously reported H2PO4Ϫ and FϪ selective CHEMFETs,
selectivity can be introduced towards organic acetate anions.
N-(5-tert-Butyl-3-formyl-2-hydroxyphenyl)octanamide (1h)
To a solution of 0.50 g (3.0 mmol) of 2-amino-4-tert-
butylphenol and 0.46 mL of Et3N in 50 mL of CHCl3 was
added 0.56 mL (3.3 mmol) of octanoyl chloride at 0 ЊC. After
stirring for 4 h 50 mL of water was added and the organic layer
was washed with 0.1 M HCl. After drying over MgSO4 the
solvent was evaporated, yielding crude N-(5-tert-butyl-2-
hydroxyphenyl)octanamide in quantitative yield. Mp: 74–75 ЊC.
1H NMR δ 8.75 (s, 1H, OH), 7.48 (s, 1H, NH), 7.15 (dd, 1H,
J = 8.5 and 2.3 Hz, ArH), 6.95 (d, 1H, J = 8.6 Hz, ArH), 6.92
(d, 1H, J = 2.3 Hz, ArH), 2.45 (t, 2H, J = 7.8 Hz, OCH2), 1.75–
1.70 (m, 2H, OCH2CH2), 1.45–1.26 (m, 17H, (CH2)4CH3 and
C(CH3)3), 0.88 (t, 3H, J = 6.5 Hz, CH2CH3). 13C NMR δ 173.6
(s), 146.5 (s), 143.5 (s), 124.7 (s), 124.4 (d), 119.6 (d), 119.0 (d),
37.0 (t), 34.0 (s), 31.6 (t), 31.4 (q), 29.1 (t), 29.0 (t), 25.8 (t),
22.6 (t), 14.17 (q). MS-FAB m/z 292.2 ([M ϩ H]ϩ, calcd. for
C18H29NO2 292.2). Since this intermediate compound slowly
decomposes, the crude product was used for further reactions.
According to the procedure for the synthesis of 1c,4 aldehyde 1h
was prepared starting with 0.88 g (3 mmol) of N-(5-tert-butyl-
2-hydroxyphenyl)octanamide. The crude product was purified
using column chromatography (SiO2, CH2Cl2–hexane 2:3)
yielding 0.47 g (50%) of the product as an off-white solid. Mp:
83–84 ЊC. 1H NMR δ 11.29 (s, 1H, ArOH), 9.86 (s, 1H,
ArCHO), 8.79 (d, 1H, J = 2.2 Hz, ArH), 7.71 (br s, 1H, ArNH),
7.24 (d, 1H, J = 2.3 Hz, ArH), 2.42 (t, 2H, J = 7.3 Hz,
C(O)CH2), 1.75–1.70 (m, 2H, C(O)CH2CH2), 1.32–1.24 (m,
17H, (CH2)4CH3 and C(CH3)3), 0.87 (t, 3H, J = 6.5 Hz,
CH2CH3). 13C NMR δ 197.0 (d), 171.7 (s), 147.9 (s), 143.4 (s),
127.1 (s), 124.6 (d), 123.3 (d), 119.1 (s), 37.9 (t), 34.5 (s), 31.7 (t),
31.2 (q), 29.2 (t), 29.0 (t), 25.4 (t), 22.6 (t), 14.1 (q). MS-EI m/z
319.1 (Mϩ, calcd. 319.2), 193.0 ([M ϩ H Ϫ C(O)C7H15]ϩ).
Anal. Calcd. for C19H29NO3: C, 71.4; H, 9.2; N, 4.4. Found: C,
71.6; H, 9.3; N, 4.5%.
Experimental
Synthesis
NMR spectra were recorded in CDCl3 on a Bruker AC 250
spectrometer. Residual solvent hydrogen atoms were used as
internal standard and chemical shifts are given in ppm relative
to TMS. Ion fast atom bombardment (FAB) mass spectra were
obtained with m-nitrobenzyl alcohol as a matrix. Melting
points are uncorrected. CH2Cl2 was distilled from CaCl2 and
stored over molecular sieves (4 Å). All commercially available
chemicals were of reagent grade quality from Acros, Aldrich,
or Merck, and were used without further purification. Bis-
(dodecyloxy)derivative 24 and aldehydes 1g2 and 52 were made
according to literature procedures.
CAUTION: Care should be taken when handling uranyl-
containing compounds because of their toxicity and radio-
activity.10
2-Methoxymethoxy-1,1Ј-biphenyl (4)
Bisamine intermediate 8
To a suspension of 14.2 mmol of NaH in 20 mL of dry DMF
2 g (11.8 mmol) of 2-phenylphenol was added at 55 ЊC. After
20 min the solution was allowed to cool to 35 ЊC and 1.25 mL
of bromomethyl methyl ether (tech., 90%) was slowly added
during 15 min. After 30 min the reaction was quenched by the
addition of 1 mL of MeOH, 50 mL of toluene was added to the
solution and the reaction mixture was washed with 50 mL of
water. The aqueous layer was extracted with 50 mL of toluene,
A solution of 0.6 g (2.9 mmol) of N-(5-tert-butyl-3-formyl-2-
hydroxyphenyl)acetamide (1c) in 15 ml of hydrazine mono-
hydrate was stirred for 3 days at 70 ЊC. Evaporation yielded the
crude product which was triturated with EtOH. The product
was obtained as a yellow solid in quantitative yield. Mp 222–
1
224 ЊC. H NMR δ 8.69 (s, 2H, imine NCH), 6.93 (d, 2H,
J = 2.2 Hz, ArH), 6.79 (d, 2H, J = 2.2 Hz, ArH), 3.90 (br s, 4H,
J. Chem. Soc., Perkin Trans. 2, 1999, 1211–1218
1215

View Article Online
1
NH2), 1.32 (s, 18H, C(CH3)3). 13C NMR δ 164.5 (d), 144.7 (s),
142.3 (s), 134.3 (s), 117.9 (d), 116.0 (d), 115.4 (s), 113.3 (d), 33.5
(s), 30.9 (q). MS-FAB m/z 382.2 (Mϩ, calcd. 382.2). Anal.
Calcd. for C22H30N4O2: C, 69.1; H, 7.9; N, 14.7. Found: C, 69.7;
H, 7.9; N, 14.7%.
0.48 g (69%). Mp: 209–210 ЊC. H NMR δ 9.35 (s, 2H, imine
NCH), 7.84 (dd, 4H, J = 7.0 and 1.4 Hz, ArH), 7.68 (dd, 2H,
J = 1.7 and 7.3 Hz, ArH), 7.63 (dd, 2H, J = 7.9 and 1.6 Hz,
ArH), 7.50 (t, 4H, J = 7.0 Hz, ArH), 7.39 (t, 2H, J = 7.2 Hz,
ArH), 7.11 (s, 2H, phenylene diamine ArH), 6.81 (t, 2H, J = 7.5
Hz, ArH), 4.14 (t, 4H, J = 6.5 Hz, OCH2), 1.90–1.85 (m, 4H,
OCH2CH2), 1.60–1.20 (m, 36H, OCH2CH2(CH2)9), 0.88 (t, 6H,
J = 6.3 Hz, CH2CH3). 13C NMR δ 166.9 (s), 163.7 (d), 150.3 (s),
140.1 (s), 139.7 (s), 136.1 (d), 134.8 (d), 132.5 (s), 130.1 (d),
128.1 (d), 127.0 (d), 124.5 (s), 118.0 (d), 104.5 (d), 69.9 (t), 31.9
(t), 29.7 (t), 29.6 (t), 29.4 (t), 29.3 (t), 26.1 (t), 22.7 (t), 14.1 (q).
MS-FAB m/z 1106.0 ([M ϩ H]ϩ, calcd. 1105.6). Anal. Calcd.
for C56H70N2O6UؒH2O: C, 59.9; H, 6.5; N, 2.5. Found: C, 60.0;
H, 6.5; N, 2.6%.
Bisurea intermediate 9
To a solution of 0.18 g (0.47 mmol) of 8 in 30 ml of CH2Cl2 was
added 0.18 ml (1.88 mmol) of propyl isocyanate. After stirring
the solution overnight at room temperature water was added to
destroy the excess of isocyanate, and subsequently the solvent
was evaporated. The crude product was triturated with MeOH.
Filtration yielded 0.14 g (54%) of the product as a yellow solid.
1
Mp: 227–229 ЊC. H NMR (DMSO-d6) δ 8.66 (s, 2H, imine
NCH), 8.35 (d, 2H, J = 2.6 Hz, ArH), 7.86 (s, 2H, ArNH), 6.93
(d, 2H, J = 2.6 Hz, ArH), 6.70 (br t, 2H, CH2NH), 3.09 (q, 4H,
J = 7.0 Hz, CH2NH), 1.53–1.40 (m, 4H, CH2CH2CH3), 1.23 (s,
18H, C(CH3)3), 0.87 (t, 6H, J = 7.3 Hz, CH2CH3). 13C NMR
δ 164.2 (d), 155.8 (s), 145.2 (s), 142.0 (s), 137.5 (s), 128.1 (d),
120.0 (d), 115.5 (s), 41.5 (t), 33.9 (s), 31.4 (q), 22.8 (t), 11.1 (q).
MS-FAB m/z 553.3 ([M ϩ H]ϩ, calcd. 554.1) Anal. Calcd. for
C30H44N6O4ؒ1.5MeOH: C, 62.9; H, 8.4; N, 14.0. Found: C, 62.9;
H, 8.2; N, 13.9%.
{4,4Ј,6,6Ј-Tetra-tert-butyl-2,2Ј-[4,5-bis(dodecyloxy)-1,2-
phenylenebis(nitrilo-êN-methylene)]diphenolato-êO}dioxo-
uranium (3f). Yield 0.41 g (53%), recrystallized from CH2Cl2.
Mp: 275–278 ЊC. 1H NMR δ 9.36 (s, 2H, imine NCH), 7.75 (d,
2H, J = 2.4 Hz, phenol ArH), 7.47 (d, 2H, J = 2.3 Hz, phenol
ArH), 7.06 (s, 2H, phenylene diamine ArH), 4.13 (t, 4H, J = 6.5
Hz, phenol ArH), 1.90–1.85 (m, 4H, OCH2CH2), 1.71 (s, 9H,
C(CH3)3), 1.60–1.20 (m, 54H, OCH2CH2(CH2)9 and C(CH3)3),
0.87 (t, 6H, J = 6.3 Hz, CH3). 13C NMR δ 167.3 (d), 164.4 (s),
149.9 (s), 140.4 (s), 139.4 (s), 139.2 (s), 131.1 (d), 129.7 (d), 124.4
(s), 104.8 (d), 69.9 (t), 35.2 (s), 33.9 (s), 31.9 (t), 31.6 (q), 30.2
(q), 29.7 (t), 29.6 (t), 29.5 (t), 29.4 (t), 26.1 (t), 22.7 (t), 14.1 (q).
MS-FAB m/z 1176.7 (Mϩ, calcd. 1176.8). Anal. Calcd. for
C60H94N2O6Uؒ0.75CH2Cl2: C, 58.8; H, 7.8; N, 2.3. Found: C,
58.7; H, 8.0; N, 2.4%.
N-(5-tert-Butyl-3-formyl-2-hydroxyphenyl) propyl urea (1i)
A mixture of 0.26 g (0.47 mmol) of 9, 0.09 g (0.52 mmol)
CuCl2ؒ2H2O, 1.5 mL (0.05 M) phosphate buffer, 2.5 ml H2O,
and 8 ml THF was stirred at 50 ЊC for 6 h. The reaction mixture
was evaporated and washed with water and brine. After drying
over Na2SO4, the solvent was evaporated. The crude product
could be purified using column chromatography (SiO2,
CH2Cl2–EtOAc 9:1). The product was obtained as a yellow
solid in quantitative yield. Mp 165–168 ЊC. 1H NMR δ 11.15 (s,
1H, ArOH), 9.77 (s, 1H, ArCHO), 8.44 (d, 1H, J = 2.2 Hz,
ArNH), 7.09 (d, 1H, J = 2.3 Hz, ArH), 5.26 (br t, CH2NH), 3.17
(q, 2H, J = 6.9 Hz, NHCH2), 1.57–1.42 (m, 2H, CH2CH2CH3),
1.24 (s, 9H, C(CH3)3), 0.87 (t, 3H, J = 7.4 Hz, CH3). 13C NMR
δ 197.1 (d), 155.3 (s), 147.9 (s), 143.3 (s), 128.1 (s), 124.1 (d),
122.0 (d), 119.1 (s), 42.2 (t), 34.5 (s), 31.2 (q), 23.3 (t), 11.4 (q).
MS-FAB 279.2 ([M ϩ H]ϩ 279.2). Anal. Calcd. for C15H22-
N2O3: C, 64.7; H, 8.0; N, 10.1. Found: C, 64.6; H, 8.0; N, 9.9%.
{6,6Ј-Bis[2-(4-Methylphenylamino)-2-oxoethoxy]-2,2Ј-[4,5-
bis(dodecyloxy)-1,2-phenylenebis(nitrilo-êN-methylene)]-
diphenolato-êO}dioxouranium (3g). Yield 0.24 g (30%). Mp:
172–174 ЊC. 1H NMR (DMSO-d6) δ 10.63 (s, 2H, NH), 9.62 (s,
2H, imine NCH), 7.67 (d, 4H, J = 8.4 Hz, methylphenyl ArH),
7.55–7.50 (m, 6H, phenylene diamine ArH and phenol ArH),
6.95 (d, 4H, J = 8.3 Hz, methylphenyl ArH), 6.73 (t, 2H, J = 7.8
Hz, phenol ArH), 4.98 (s, 4H, OCH2C(O)), 4.18 (t, 4H, J = 6.0
Hz, OCH2(CH2)10), 2.19 (s, 6H, ArCH3), 1.78 (m, 4H,
OCH2CH2), 1.50–1.20 (m, 36H, OCH2CH2(CH2)9), 0.86 (t, 6H,
J = 6.1 Hz, CH2CH3); (CDCl3) 12.78 (s, 1H), 10.54 (s, 1H), 9.34
(s, 1H), 9.17 (s, 1H), 7.38 (br s, 2H), 7.23 (d, 4H, J = 7.0 Hz),
7.07 (s, 2H), 7.02 (d, 1H, J = 7.6 Hz), 6.83 (d, 1H, J = 7.6 Hz),
6.60–6.55 (m, 2H), 6.44 (d, 2H, J = 8.3 Hz), 5.75 (d, 2H J = 7.0
Hz), 5.55 (d, 1H, J = 15.9 Hz), 4.70 (d, 1H, J = 17.7 Hz), 4.30–
4.05 (m, 6H), 1.98 (s, 3H), 1.90–1.85 (m, 4H), 1.65 (s, 3H), 1.51–
1.20 (m, 36H), 0.81 (t, 6H, J = 5.5 Hz). 13C NMR (DMSO-d6)
δ 167.4 (s), 164.9 (d), 160.4 (s), 149.8 (s), 149.3 (s), 139.9 (s),
135.8 (s), 132.5 (s), 129.5 (d), 129.0 (d), 125.1 (s), 122.6 (d),
119.6 (d), 116.5 (d), 105.1 (d), 71.2 (t), 68.9 (t), 31.3 (t), 29.1 (t),
29.0 (t), 28.8 (t), 28.7 (t), 25.7 (t), 22.1 (t), 20.3 (q), 13.9 (q). IR
(KBr) ν 1608 (C᎐O, C᎐N), 908 (OUO) cmϪ1. MS-FAB m/z
General procedure for the synthesis of UO2 salophenes 3d–i
A solution of 1.3 mmol of the appropriate aldehyde (3-
fluorosalicylaldehyde (1d), 1e, 3,5-di-tert-butylsalicylaldehyde
(1f), 1g, 1h, or 1i) and 0.3 g (0.65 mmol) of diamine 2 in 25 mL
of methanol was refluxed for 1 h. Subsequently 0.27 g (0.65
mmol) of UO2(OAc)2ؒ2H2O was added, and refluxing was con-
tinued for another 1 h. After the solution had cooled down, the
precipitate was filtered off and washed with cold methanol to
yield 3d–i as an orange or red solid.
᎐
᎐
1301.6 ([M ϩ Na]ϩ, calcd. 1301.6). Anal. Calcd. for C62H80N4-
{6,6Ј-Difluoro-2,2Ј-[4,5-bis(dodecyloxy)-1,2-phenylene-
O10U: C, 58.2; H, 6.3; N, 4.4. Found: C, 58.1; H, 6.1; N, 4.5%.
bis(nitrilo-êN-methylene)]diphenolato-êO}dioxouranium (3d).
1
Yield 0.45 g (70%). Mp: 155–158 ЊC. H NMR δ 9.28 (s, 2H,
{4,4Ј-Di-tert-butyl-6,6Ј-bis(octanamido)-2,2Ј-[4,5-bis-
imine NCH), 7.60–7.29 (m, 4H, phenol ArH), 7.02 (s, 2H,
phenylene diamine ArH), 6.65 (br d, 2H, phenol ArH), 4.02
(t, 4H, J = 6.3 Hz, OCH2), 1.80–1.75 (m, 4H, OCH2CH2), 1.60–
1.20 (m, 36H, OCH2CH2(CH2)9), 0.80 (t, 6H, J = 6.3 Hz, CH3).
13C NMR δ 163.5 (d), 156.5 (s), 152.6 (s), 150.4 (s), 140.1 (s),
129.8 (d), 126.3 (s), 120.6 (d), 117.2 (d), 104.7 (d), 69.9 (t), 31.9
(t), 29.8 (t), 29.7 (2 × t), 29.5 (t), 29.4 (t), 29.2 (t), 26.1 (t), 22.7
(t), 14.2 (q). MS-FAB m/z 989.9 ([M ϩ H]ϩ, calcd. 989.5). Anal.
Calcd. for C44H60F2N2O6Uؒ1.5H2O: C, 52.0; H, 6.3; N, 2.8.
Found: C, 51.8; H, 6.2; N, 2.9%.
(dodecyloxy)-1,2-phenylenebis(nitrilo-êN-methylene)]diphenol-
ato-êO} dioxouranium (3h). The crude product was purified by
column chromatochraphy (Al2O3). The impurities were
removed with CH2Cl2–EtOAc 7:3 as eluent, after which the
eluent polarity was increased to CH2Cl2–MeOH 95:5. Yield
0.53 g (60%). Mp: 123–126 ЊC. 1H NMR (DMSO-d6) δ 9.62 (s,
2H, imine NCH), 9.09 (s, 2H, NH), 8.75 (s, 2H, phenol ArH),
7.50 (br s, 4H, phenol ArH and phenylene diamine ArH), 4.16
(br t, 4H, OCH2), 2.65 (br t, 2H, NHC(O)CH2), 1.75–1.75 (m,
4H, OCH2CH2), 1.60–1.20 (m, 74H, OCH2CH2(CH2)9,
C(O)CH2(CH2)5 and C(CH3)3), 0.85 (br t, 6H, (CH2)11CH3),
0.70 (br t, 6H, (CH2)6CH3); (CDCl3) δ 11.25, 8.86 (2 × s, 2H,
NH), 9.34, 9.20 (2 × s, 2H, imine NCH), 9.00, 7.14 (2 × d, 2H,
{3,3Ј-[4,5-Bis(dodecyloxy)-1,2-phenylenebis(nitrilo-êN-meth-
ylene)]bis(1,1Ј-biphenyl-2-olato-êO)}dioxouranium (3e). Yield
1216
J. Chem. Soc., Perkin Trans. 2, 1999, 1211–1218

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J = 2.3 Hz, phenol ArH), 7.54, 7.26 (2 × d, 2H, J = 3.4 Hz
phenol ArH), 7.05, 7.06 (2 × s, 2H phenylene diamine ArH),
4.14–4.04 (m, 4H, OCH2), 2.50, 2.43 (2 × t, 4H, J = 7.3
Hz, NHC(O)CH2), 1.85–1.80, 1.75–1.70 (m, 4H, OCH2CH2),
1.50–1.10 (m, 74H, OCH2CH2(CH2)9, C(O)CH2(CH2)5 and
C(CH3)3), 0.81 (br t, 6H, (CH2)11CH3), 0.71, 0.53 (2 × t, 6H,
J = 6.9 Hz, (CH2)6CH3). 13C NMR (DMSO-d6) δ 170.9 (s),
165.3 (d), 156.5 (s), 149.2 (s), 139.8 (s), 138.4 (s), 129.4 (d), 124.8
(s), 121.9 (d), 105.0 (d), 68.9 (t), 33.7 (s), 31.4 (q), 31.3 (2 × t),
31.1 (t), 29.1 (2 × t), 28.7 (2 × t), 25.7 (t), 25.1 (t), 22.1 (t), 13.9
(2 × q). MS-FAB m/z 1347.9 ([M ϩ H]ϩ, calcd. 1348.0). Anal.
Calcd. for C68H108N4O8U: C, 60.6; H, 8.1; N, 4.2. Found: C,
60.9; H, 8.0; N, 4.3%.
(CDCl3) δ 11.02 (d, 1H , J = 7.7 Hz, NH), 9.41, 9.34 (2 × s, 2H,
imine NCH), 9.05, 7.14 (2 × d, 2H, J = 2.3 Hz, phenol ArH),
9.00 (s, 1H, NH), 7.26, 7.14 (2 × d, 2H, J = 3.4 Hz, phenol
ArH), 4.76–4.73 (br m, 2H, cyclohexyl CH), 2.56 (m, 6H,
J = 7.2 Hz, C(O)CH2, cyclohexyl CH2), 2.00–1.20 (m, 44H,
cyclohexyl CH2, C(O)CH2(CH2)5 and C(CH3)3), 0.82, 0.68 (t,
6H, J = 6.2 Hz, (CH2)11CH3); 13C NMR (DMSO-d6) δ 170.8 (s),
168.6 (d), 155.7 (s), 138.1 (s), 129.1 (s), 129.4 (d), 121.2 (s), 120.6
(d), 70.6 (d), 37.0 (t), 33.7 (s), 31.4 (q), 31.3 (t), 28.8 (t), 28.7 (t),
27.4 (t), 25.1 (t), 22.1 (t), 21.4 (t), 13.9 (q). MS-FAB m/z 985.7
([M ϩ H]ϩ, calcd. 985.6). Anal. Calcd. for C44H66N4O6Uؒ
1.5H2O: C, 52.2; H, 6.9; N, 5.5. Found: C, 51.9; H, 6.8; N, 5.4%.
ISE and CHEMFET measurements
{4,4Ј-Di-tert-butyl-6,6Ј-(propylaminocarbonylamino)-2,2Ј-
[4,5-bis(dodecyloxy)-1,2-phenylenebis(nitrilo-êN-methylene)]-
diphenolato-êO}dioxouranium (3i). The crude product was
purified by column chromatography (SiO2, CH2Cl2–MeOH
95:5). Yield 0.41 g (50%). Mp 164–167 ЊC. 1H NMR (DMSO-
d6) δ 9.49 (s, 2H, imine NCH), 8.68 (d, 2H, J = 2.6 Hz, ArH),
8.28 (s, 2H, ArNH), 7.48 (br t, NHCH2), 7.42 (s, 2H, phenylene
diamine ArH), 7.27 (d, 2H, J = 2.6 Hz, ArH), 4.17 (br t, 4H,
J = 6.2 Hz, OCH2), 3.20–3.13 (m, 4H, NHCH2), 1.81–1.74 (m,
propyl CH2CH3), 1.59–1.46 (m, 4H, CH2CH3), 1.30 (s, 36H,
(CH2)9), 1.25 (s, 18H, C(CH3)3), 0.97 (t, 6H, J = 7.3 Hz, CH3),
0.85 (t, 6H, J = 7.0 Hz, CH3). 13C NMR δ 165.2 (s), 156.3 (d),
155.3 (s), 149.1 (s), 140.2 (s), 138.0 (s), 131.1 (s), 121.8 (d), 121.1
(d), 105.0 (t), 33.5 (s), 31.3 (t), 31.1 (t), 29.1 (t), 29.0 (t), 28.8 (t),
28.7 (t), 25.6 (t), 22.0 (t), 13.5 (q), 11.2 (q). MS-FAB m/z 1287.6
([M ϩ Na]ϩ, calcd. 1287.8). Anal. Calcd. for C60H94N6O8Uؒ
MeOH: C, 56.5; H, 7.6; N, 6.5. Found: C, 56.5; H, 7.4; N, 6.8%.
Reagents. High molecular weight (HMW) PVC was obtained
from Fluka. o-Nitrophenyl n-octyl ether (NPOE) was syn-
thesized according to a literature procedure.11 Tetraoctyl-
ammonium bromide (TOAB) was purchased from Fluka. THF
was freshly distilled from sodium–benzophenone ketyl before
use. The anion sodium salts were of analytical grade (Fluka).
All solutions were made with deionized doubly distilled water.
The measurements were carried out in solution with 0.01 M
2-morpholinoethanesulfonic acid (MES, Fluka) adjusted to
the desired pH with NaOH.
Fabrication of ISEs and measurements. The ion-selective
membranes were prepared by dissolving in 0.7 mL of THF
approximately 100 mg of a mixture composed of 33 wt% PVC,
66 wt% NPOE, 1 wt% receptor, and 20 mol% (with respect to
the receptor) of TOAB. This solution was poured into a glass
ring (id 24 mm) resting on a glass plate. After evaporation of
the THF overnight, disks of 7 mm id were cut. The membrane
disks were mounted in electrode bodies (Philips IS 561). As
internal filling solution 0.1 M KCl was used. Membrane poten-
tials were measured vs. a saturated calomel electrode (SCE),
connected to the stirred sample solution via a salt bridge filled
with 1.0 M LiOAc. The ISE response data were collected with
a Zeus Mux 03 14ch multiplexer. After changing the sample
the ISEs were conditioned for 5 min before measuring the
{27,28-Bis(dodecyloxy)-6,17-dioxo-6,7,8,9,11,12,15,16,17,18-
decahydro-5H,14H-tribenzo[qr,u,za1][1,7,10,16,4,13,21,24]-
tetraoxatetraazoctacosin-ê2N25,30-3a1,19a1-diolato-êO}-
dioxouranium (6). To a refluxing solution of Ba(OTf)2 (0.57 g,
1.0 mmol) in 50 mL of MeOH were added two separate sol-
utions of bisaldehyde 52 (0.24 g, 0.47 mmol) in 50 mL MeOH
and 2 (0.22 g, 0.47 mmol) in 50 mL of MeOH using a perfusor
in 0.5 h. After 0.5 h 0.20 g (0.47 mmol) of UO2(OAc)2ؒ2H2O in
10 mL of MeOH was added and reflux was maintained for 0.5
h. The reaction mixture was evaporated and washed with a
large amount of water. Recrystallization from CH2Cl2–MeOH
yielded 0.29 g (65%) of 6. Mp: 185–186 ЊC. 1H NMR δ 9.27 (s,
2H, imine NCH), 9.20 (s, 2H, NH), 7.29 (d, 2H, phenol ArH),
7.07 (s, 2H, phenylene diamine ArH), 6.87 (d, 2H, J = 7.1 Hz,
phenol ArH), 6.51 (t, 2H, J = 7.9 Hz, phenol ArH), 4.61 (s, 4H,
OCH2C(O)), 4.12 (t, 4H, J = 6.4 Hz, OCH2(CH2)10), 3.70 (br s,
8H, CH2OCH2), 3.58 (br s, 4H, NHCH2), 1.90–1.85 (m, 4H,
OCH2CH2), 1.50–1.20 (m, 36H, OCH2CH2(CH2)9), 0.87 (t, 6H,
J = 6.1 Hz, CH2CH3). 13C NMR (DMSO-d6) δ 163.3 (s), 160.1
(d), 150.4 (s), 149.6 (s), 140.3 (s), 124.4 (d), 117.7 (d), 104.6 (d),
77.2 (d) , 69.9 (t), 31.9 (t), 29.7 (2 × t), 29.4 (2 × t), 29.2 (t), 26.1
membrane potential. The potentiometric selectivity coefficients
Pot
i,j
(K ) were determined by the separate solution method
(SSM)12 with 0.1 M sodium salt solutions, 0.01 M MES,
pH = 6.0. The response towards pH changes was obtained by
the addition of small volumes of 1.0 M or 0.01 M NaOH
solution to 40 mL of an 0.1 M Na2SO4 solution pH 4.5, under
an argon atmosphere.
Fabrication of CHEMFETs and measurements. CHEMFETs
were prepared from ISFETs with dimensions of 3 × 4.5 mm
fabricated in the MESA cleanroom facilities (University of
Twente, The Netherlands), mounted on a printed circuit board,
wire bonded, and encapsulated with epoxy resin (Hysol H-W
796/C8 W795). Details of the modification of the ISFETs with
poly(hydroxyethylmethacrylate) hydrogel (polyHEMA) have
been described before.13 The membrane was deposited on the
gate area of the CHEMFET by casting this solution using a
micropipet (3 × 1.5 µl). The solvent was allowed to evaporate
overnight. The composition of the membrane solution and the
(t), 22.7 (t), 14.1 (q). IR (KBr) ν 1653 (C᎐O), 1606 (C᎐N), 903
᎐
᎐
(OUO) cmϪ1. MS-FAB m/z 1213.4 ([M ϩ H]ϩ, calcd. 1213.6).
Anal. Calcd. for C56H84N4O8Uؒ2CH2Cl2: C, 48.6; H, 6.0; N, 4.1.
Found: C, 48.8; H, 5.9; N, 4.4%.
{4,4Ј-Di-tert-butyl-6,6Ј-bis(octanamido)-2,2Ј-[1,2-cyclohexyl-
enebis(nitrilo-êN-methylene)]diphenolato-êO}dioxouranium (7).
cis-1,2-Diaminocyclohexane (0.03 g, 0.24 mmol) was reacted
with 0.15 g (0.47 mmol) of 1h, and 0.1 g (0.24 mmol) of
UO2(OAc)2ؒ2H2O according to the general procedure for the
synthesis of salophenes, yielding 0.16 g (70%) of salene 7. Mp:
measurement procedures have been described previously.4 The
potentiometric selectivity coefficients (K ) were determined by
Pot
i,j
the fixed interference method (FIM) according to IUPAC
recommendations.12 Detection limits and selectivity coefficients
were determined 0.1, slopes 2 mV decadeϪ1. The constant
background concentration of the interfering ion was 0.1 M
unless otherwise indicated. All concentrations were converted
to single-ion activities, and the mean activity coefficient
was obtained by the extended Debye–Hückel equation. The
measurements were performed at ambient temperature in an
air-conditioned room (T = 22 ЊC).
1
220–221 ЊC. H NMR (DMSO-d6) δ 9.87 (s, 2H, imine NCH),
9.07 (s, 2H, NH), 8.75 (d, 2H, J = 2.1 Hz, phenol ArH), 7.39 (d,
2H, J = 2.1 Hz, phenol ArH), 4.7 (br m, 2H, cyclohexyl CH),
2.63 (t, 2H, J = 7.2 Hz, C(O)CH2), 2.37–2.34 (br m, 2H, cyclo-
hexyl CH2), 1.90–1.20 (m, 44H, cyclohexyl CH2, C(O)CH2-
(CH2)5 and C(CH3)3), 0.88 (t, 6H, J = 6.1 Hz, (CH2)11CH3);
J. Chem. Soc., Perkin Trans. 2, 1999, 1211–1218
1217

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7 A. R. van Doorn, M. Bos, S. Harkema, J. van Eerden, W. Verboom
and D. N. Reinhoudt, J. Org. Chem., 1991, 56, 2371.
8 M. M. G. Antonisse, B. H. M. Snellink-Ruël, J. F. J. Engbersen and
D. N. Reinhoudt, J. Org. Chem., 1998, 63, 9776.
References and notes
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