Water-Soluble Neutral Calix[4]arene-Lanthanide Complexes: Synthesis and Luminescence Properties

Article abstract of DOI:10.1021/jo970132j

Water-soluble calix[4]arenes 10a,b with chromophores ("antenna") attached to the lower rim via a short spacer are described. In the neutral lanthanide complexes of 10a,b photoexcitation of the antenna induces lanthanide emission via intramolecular energy transfer. Calix[4]arene 10b with a chrysene moiety as sensitizer shows strong lanthanide emission for Eu³⁺ with an excitation maximum at λ = 363 nm.

Full text of DOI:10.1021/jo970132j

J . Org. Chem. 1997, 62, 4229-4235
4229
Wa ter -Solu ble Neu tr a l Ca lix[4]a r en e-La n th a n id e Com p lexes:
Syn th esis a n d Lu m in escen ce P r op er ties
Frank J . Steemers, Hans G. Meuris, Willem Verboom, and David N. Reinhoudt*
Laboratory of Supramolecular Chemistry and Technology, University of Twente, P.O. Box 217,
7500 AE Enschede, The Netherlands
Erik B. van der Tol and J an W. Verhoeven*
Laboratory of Organic Chemistry, University of Amsterdam, Nieuwe Achtergracht 129,
1018 WS Amsterdam, The Netherlands
Received J anuary 24, 1997X
Water-soluble calix[4]arenes 10a ,b with chromophores (“antenna”) attached to the lower rim via a
short spacer are described. In the neutral lanthanide complexes of 10a ,b photoexcitation of the
antenna induces lanthanide emission via intramolecular energy transfer. Calix[4]arene 10b with
a chrysene moiety as sensitizer shows strong lanthanide emission for Eu3+ with an excitation
maximum at λ ) 363 nm.
In tr od u ction
reported the encapsulation of a lanthanide ion by a
tetraamide calix[4]arene to give a water-soluble system,
while Shinkai et al.16 prepared lanthanide complexes via
complexation of the phenolic oxygen atoms of water-
soluble calix[n]arenes. However, such lanthanide com-
plexes based on calix[4]arenes are positively charged,
which might lead to aspecific binding in biological
systems.17
There is considerable interest in the synthesis of
molecular probes for imaging or bioassay purposes.1-3
Particularly interesting are lanthanide probes because
of their unique characteristics like exceptionally large
Stoke shifts (∼200-300 nm), narrow emission line spec-
tra, long-wavelength emission (∼500-600 nm), and long
luminescence lifetimes (∼600-1000 ms).4,5 This explains
the strong motivation for the synthesis of ligands for
these lanthanide ions that form complexes with high
kinetic stability and that are soluble in water for coupling
reactions to biomolecules.6-13
Recently, we described calixarene derivatives that are
substituted with three carboxylic acid groups and which
form neutral complexes with lanthanide cations.18 When
we attached a triphenylene antenna chromophore to such
calix[4]arenes they showed a strong sensitizing ability
toward Eu3+ and Tb3+, allowing the excitation of Eu3+
and Tb3+ with wavelengths extending to 350 nm.19
Various calix[4]arene derivatives are suitable for the
complexation of trivalent cations, but in most cases they
are not soluble in water.14 Only Sabbatini et al.15
For a simple coupling to biomolecules, these calix[4]-
arene lanthanide probes should be water-soluble.20 In
the literature, different types of water-soluble calix[4]-
arenes have been reported that have hydrophilic sub-
* To whom correspondence should be addressed. (D.N.R.) Phone:
+ 31 53 4892980. Fax: + 31 4894645. E-mail: SMCT@ct.utwente.nl.
(J .W.V.) Phone: + 31 20 5255676. Fax: + 31 20 5255670. E-mail:
J WV@org.chem.uva.nl.
- 21
- 22
stituents such as SO3
,
COO-, PO3
,
SO2N(CH2CH2-
X Abstract published in Advance ACS Abstracts, J une 15, 1997.
(1) Bailey, M. P.; Rocks, B. F.; Riley, C. In Nonisotopic Immunoassay;
Ngo, T. T., Ed.; Plenum: New York, 1988; p 187.
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Photobiol. 1995, 3.
OH)2,23 N+Me3,24 or polyethyleneoxy chains.25,26 Recently,
we have reported neutral water-soluble calix[4]arenes by
(3) Mayer, A.; Neuenhofer, S. Angew. Chem., Int. Ed. Engl. 1994,
33, 1044.
(4) Horrocks, W., DeW., J r.; Sudnick, D. R. Acc. Chem. Rev. 1981,
14, 384.
(16) Sato, N.; Yoshida, I.; Shinkai, S. Chem. Lett. 1993, 1261.
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Shionoya, M.; Koike, T.; Kimura, E. J . Org. Chem. 1993, 58, 6895.
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Soc., Chem. Commun. 1995, 1879.
(8) Selvin, P. R.; Li, M. J . Am. Chem. Soc. 1995, 117, 8132.
(9) Mukkala, V.-M.; Helenius, M.; Hemmila¨, I.; Kankare, J .; Takalo,
H. Helv. Chim. Acta 1993, 76, 1361.
(10) Mikola, H.; Takalo, H.; Hemmila¨, I. Bioconjugate Chem. 1995,
6, 235.
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1996, 79, 789.
(18) Rudkevich, D. M.; Verboom, W.; van der Tol, E. B.; van
Staveren, C. J .; Kaspersen, F. M.; Verhoeven, J . W.; Reinhoudt, D. N.
J . Chem. Soc., Perkin Trans. 2 1995, 131.
(19) Steemers, F. J .; Verboom, W.; Reinhoudt, D. N.; van der Tol,
E. B.; Verhoeven, J . W. J . Am. Chem. Soc. 1995, 117, 9408.
(20) Iwema Bakker, W. I.; Haas, M.; Khoo-Beattie, C.; Ostaszewski,
R.; Franken, S. M.; Den Hertog, J r., H. J .; Verboom, W.; de Zeeuw, D.;
Harkema, S.; Reinhoudt, D. N. J . Am. Chem. Soc. 1994, 116, 123.
(21) (a) Shinkai, S.; Mori, S.; Tsubaki, T.; Sone, T.; Manabe, O.
Tetrahedron Lett. 1984, 24, 5315. (b) Shinkai, S.; Mori, S.; Koreishi,
H.; Tsubaki, T.; Manabe, O. J . Am. Chem. Soc. 1984, 108, 2409. (c)
Arduini, A.; Pochini, A.; Reverberi, S.; Ungaro, R. J . Chem. Soc., Chem.
Commun. 1984, 981.
(22) Almi, M.; Arduini, A.; Casnati, A.; Pochini, A.; Ungaro, R.
Tetrahedron 1989, 45, 2177.
(23) (a) Newkome, G. R.; Hu, Y.; Saunders, M. J . Tetrahedron Lett.
1991, 32, 1133. (b) Grote Gansey, M. H. B.; Verboom, W.; Reinhoudt,
D. N. Tetrahedron Lett. 1994, 35, 7127.
(24) Shinkai, S.; Shirahama, Y.; Tsubaki, T.; Manabe, O. J . Chem.
Soc., Perkin Trans. 1 1989 1859.
(25) Shi, Y.; Zhang, Z. J . Chem. Soc., Chem. Commun. 1994, 375.
(26) (a) Arduini, A.; Riverberi, S.; Ungaro, R. J . Chem. Soc., Chem.
Commun. 1984, 981. (b) Gutsche, C. D.; Alam, I. Tetrahedron 1988,
44, 4689.
(12) Parker, D.; Williams, J . A. G. J . Chem., Dalton Trans. 2 1996,
3613.
(13) Hemmila¨, I.; Sta˚hlberg, T.; Mottram, P. Bioanalytical Applica-
tions of Labelling Technologies; Wallac Oy: Turku, 1994.
(14) (a) Sabbatini, N.; Guardigli, M.; Manet, I.; Ziessel, R.; Ulrich,
G.; Ungaro, R.; Casnati, A.; Fischer, C. New J . Chem. 1995, 19, 137
and references cited therein. (b) Casnati, A.; Ting, Y.; Berti, D.; Fabbi,
M.; Pochini, A.; Ungaro, R.; Sciotto, D.; Lombardo, G. G. Tetrahedron
1993, 49, 9815. (c) Matsumoto, H.; Shinkai, S. Chem. Lett. 1994, 901.
(15) Sabbatini, N.; Guardighi, M.; Mecati, A.; Balzani, V.; Ungaro,
R.; Ghidini, E.; Casnati, A.; Pochini, A. J . Chem. Soc., Chem. Commun.
1990, 878.
S0022-3263(97)00132-1 CCC: $14.00 © 1997 American Chemical Society

4230 J . Org. Chem., Vol. 62, No. 13, 1997
Steemers et al.
Sch em e 1
Ch a r t 1
[[(tert-butyldimethylsilyl)oxy]methyl]methane]-2-aminoac-
etamide (3)27 (Chart 1) was coupled to calix[4]arene 6 to
afford the tetrasulfonamide 7 in 82% yield. This inter-
mediate can be used to introduce different amino-
substituted residues. Substitution31 of the trichloroethyl
group in 7 with 6-(aminomethyl)chrysene (1f) or S-(2-
pyridylthio)cysteamine (2)32 (Chart 1) and DBU as a base
in acetonitrile gave the corresponding amides 8a ,b in 63
and 67% yield, respectively. These sulfonamides (8a ,b)
were purified by chromatography over a NaCl-saturated
silica column.33
6-(Aminomethyl)chrysene (1f) was prepared from the
known 6-(bromomethyl)chrysene34 (1d ) via the phthal-
imide 1e. A Gabriel reaction of 1d afforded the phthal-
imide 1e, which after deprotection with hydrazine mono-
hydrate gave the desired 6-(aminomethyl)chrysene (1f)
in an overall yield of 95%. The precursor of 1d , 6-(hy-
droxymethyl)chrysene (1c),35 was obtained in 94% yield
the attachment of polyalcohol residues at the upper rim
of the calix[4]arene.27
In this paper, we report the synthesis and photophysi-
cal characterization of neutral, water-soluble Eu3+ and
Tb3+ complexes substituted with two aromatic sensitizer
groups (chrysene or 2-pyridyl disulfide).
(29) CHCl3 was made ethanol free by passing it through an Al2O3
column in order to prevent the substitution of the trichloroethyl ester
for an ethyl ester leading to the tetraethyl ester of tetrakis(chlorosul-
fonyl) calix[4]arene. To overcome the problem CH2Cl2 can also be used
as a solvent.
(30) Morzherin, Y.; Rudkevich, D. M.; Verboom, W.; Reinhoudt, D.
N. J . Org. Chem. 1993, 58, 7602.
Resu lts a n d Discu ssion
(31) Reductive removal of the trichloroethyl protecting group using
Zn in a 1.0 M buffered Na2PO4/NaHPO4/THF solution (1:5) yielded the
carboxylic acid derivative of 7 in 86% yield. Attempts to activate the
carboxylic acid group with various activating agents like DCC or CDI
(and catalysts: HOBT (1-hydroxybenzatriazole) or dimethylaminopy-
ridine (DMAP)) in reaction with S-(2-pyridylthio)cysteamine (2) were
unsuccessful. The 1H NMR spectrum of this carboxylic acid derivative
shows two characteristic signals for the tert-butyl groups and dimethyl
groups, indicating a partial cone conformation of the calix[4]arene,
which could explain the reduced reactivity of the carboxylic acid
functionality.
(32) Ebright, Y. W.; Chen, Y.; Pendergrast, P. S.; Ebright, R. H.
Biochemistry 1992, 31, 10664.
(33) Danks, I. P.; Sutherland, I. O. J . Inclusion Phenom. Mol. Recog.
Chem. 1992, 12, 223.
(34) Akiyama, S.; Nakasuji, K.; Nakagawa, M. Bull. Chem. Soc. J pn.
1971, 44, 2231. An alternative to prepare 6-chrysenecarboxaldehyde
(1b) is the oxidation of 6-(hydroxymethyl)chrysene. Akiyama, S.;
Nakagawa, M. Bull. Chem. Soc. J pn. 1972, 45, 259.
(35) Dewar, M. J . S.; Sampson, R. J . Bull Chem. Soc. J pn. 1957,
2946.
Syn th esis. The synthesis of water-soluble ionophores
10a ,b is depicted in Scheme 1. The water-solubility is
introduced only in the last step of the synthesis because
this facilitates handling and purification of the interme-
diates during the synthesis.
Reaction of triester-monoacid chloride calix[4]arene
5b, prepared from the monocarboxylic acid 5a ,19 with
2,2,2-trichloroethanol28 in CH2Cl2 gave the trichloroethyl
ester 5c in 96% yield. Reaction of trichloroethyl ester
29
5c with chlorosulfonic acid in CHCl3 afforded the
tetrasulfonyl calix[4]arene 6 in 61% yield.30 N-[Tris-
(27) Grote Gansey, M. H. G.; Steemers, F. J .; Verboom, W.; Rein-
houdt, D. N. Synthesis, in press.
(28) Windholz, T. B.; J ohnston, D. B. R. Tetrahedron Lett. 1967,
2555.

H2O-Soluble Neutral Calix[4]arene-Lanthanide Complexes
J . Org. Chem., Vol. 62, No. 13, 1997 4231
F igu r e 2. Energy scheme for the sensitized emission of Eu3+
and Tb3+ by chrysene. Depicted are the main luminescent
levels of Eu3+ (5D0) and Tb3+ (5D4).
F igu r e 1. Corrected excitation spectra of Eu(10a ) (‚‚‚) and
Eu(10b) (s) in Tris-HCl buffer (pH 8.0); λem ) 615 nm. The
spectra are normalized on the F0-5L6 Eu3+ transition around
7
mophore around 365 nm (see Figure 1). As we discussed
before,19 this value must come close to the longest
393 nm.
excitation wavelength possible for sensitization of Eu3+
,
in an alternative way via reduction of 6-chrysenecarbox-
aldehyde (1b)36 with BH3‚THF.
since after excitation of the chromophore first intersystem
crossing to the lowest triplet state is assumed to occur,
which can subsequently give energy transfer to the
luminescent lanthanide level (see Figure 2). For organic
(poly)aromatic systems, a minimal single-triplet energy
gap (1E00-3E00) of 5000 cm-1 may be assumed (in chry-
sene this is 7800 cm-1), while the triplet must still have
high enough energy to make the energy transfer fast and
to exclude possible (thermal) back-energy transfer. For
The selective hydrolysis of the three ethyl esters
without cleavage of the amide bonds in 8a ,b, was
achieved with K2CO3 in refluxing MeOH-H2O-THF (5:
1:2) to give the triacid derivatives 9a ,b in quantitative
yield. Removal of the TBDMS-protective groups in 9a ,b
with trifluoroacetic acid (TFA) gave the water-soluble
derivatives 10a ,b in quantitative yield. Satisfactory
mass spectra could be obtained with FRIT-FAB mass
spectrometry. The 1H NMR spectra of compounds 10a ,b
are broad at room temperature but exhibit sharp signals
at 80 °C, showing the characteristic AB system of the
methylene bridges. This points to aggregation of the
calix[4]arenes 10a ,b at room temperature.37,38 The maxi-
mum solubility of 10a in water, determined by UV
spectroscopy, is 8.0 mM at room temperature, and this
is sufficient to couple 10a to biomolecules.20
P h otop h ysica l P r op er ties. In order to investigate
the sensitizing ability of 10a and 10b in aqueous solution,
equivalent amounts of lanthanide ions (in the form of Eu-
(NO3)3‚5H2O or Tb(NO3)3‚5H2O) were added to a 1.5 ×
10-4 M solution of 10a or 10b in Tris-HCl buffer pH 8.0.
After deoxygenation by purging with argon for 15 min,
the excitation spectra of these solutions were measured
with the detection set at the emission wavelength of the
lanthanide ion (615 nm for Eu3+ and 545 nm for Tb3+).
The results for the Eu3+ complexes are shown in Figure
1. In this case, the excitation spectra in fact closely
match the respective absorption spectra. Thus, efficient
energy transfer occurs from both the 2-pyridyl disulfide
and the chrysene “antenna” leading to population of the
Eu3+ emissive state. The chrysene antenna in 10b is
particularly interesting because it allows excitation at
wavelengths compatible with readily available light
sources (e.g., a mercury arc) and with standard fluores-
cence microscope optics.
chrysene the triplet energy is 20 000 cm-1 39
only 2500
,
cm-1 above the luminescent Eu3+ level, implying that in
compound Eu(10b) probably already some back energy
transfer occurs at room temperature.
Not unexpectedly, with Tb3+ it was found that 10b does
not allow sensitized luminescence to be observed. This
again can readily be explained from the energy diagram
depicted in Figure 2, assuming that energy transfer to
the lanthanide ion occurs from the antenna triplet.
Interestingly, in the case of 10b the effect of complex-
ation with lanthanide ions is not restricted to quenching
of the chrysene triplet. This becomes evident from the
effect of adding Eu(NO3)3‚5H2O to an aqueous solution
of 10b (8.5 × 10-5 M) on the total luminescence spectrum
(see Figure 3a). In the absence of Eu3+, 10b displays the
typical fluorescence spectrum of the chrysene unit (Φfluor
) 0.15, ΦISC ) 0.85 reported for chrysene39). Upon
addition of Eu3+, the sensitized lanthanide emission
appears, and its concentration dependence (see Figure
3b) nicely confirms formation of a 1:1 complex between
10b and Eu3+. However, at the same time, the chrysene
fluorescence diminishes to about 10% of its orginal
intensity. This fluorescence quenching seems to occur
via nonspecific (dynamic) quenching and is not limited
to a 1:1 stoichiometry. For the fluorescence quenching
both direct energy transfer from the chrysene singlet
excited state to the lanthanide ion and enhanced inter-
system crossing of chrysene under the influence of a
“heavy atom effect” of the lanthanide are viable mecha-
nisms.40 However, charge-transfer interaction between
the singlet state of chrysene and the lanthanide also may
be involved. The excited-state oxidation potential of
The spectral excitation region for compound Eu(10b)
extends to the 0-0 transition of the chrysene chro-
(36) 6-Chrysenecarboxaldehyde (1b) was prepared in 71% yield from
chrysene (1a ) and R,R′-dichloromethyl methyl ether/TiCl4. An alterna-
tive to prepare the aldehyde 1b is the oxidation of 6-(hydroxymethyl)-
chrysene. Akiyama, S.; Nakagawa, M. Bull. Chem. Soc. J pn. 1972, 45,
259.
1
chrysene is estimated to be Eox* ) -2.1 V (calculated
as the ground state oxidation potential Eox ) 1.35 V vs
(37) Escamilla, G. H.; Newkome, G. R. Angew. Chem., Int. Ed. Engl.
1994, 33, 1937.
(38) Arimori, S.; Nagasaki, T.; Shinkai, S. J . Chem. Soc., Perkin.
Trans. 2 1995, 679.
(39) Murov, S. L., Carmichael, I., Hug, G. L., Eds. Handbook of
Photochemistry; Marcel Dekker, Inc.: New York, 1993.
(40) Kleinerman, M. J . Chem. Phys. 1969, 31, 2370.

4232 J . Org. Chem., Vol. 62, No. 13, 1997
Steemers et al.
F igu r e 3. (a) Total luminescence spectra of 10b (8.5 × 10-5 M) upon addition of increasing amounts of Eu(NO3)3‚5H2O in Tris-
HCl buffer (pH 8.0); deoxygenated, λex ) 363 nm. (b) Relative luminescence intensities of the chrysene fluorescence (384 nm) and
Eu3+ luminescence (614 nm) upon addition of increasing amounts of Eu(NO3)3‚5H2O or Tb(NO3)3‚5H2O to 10b in Tris-HCl buffer
(pH 8.0) for both aerated (ox) and deoxygenated (deox) solutions; λex ) 363 nm.
SCE minus the 0-0 energy E00 ) 3.45 V),39 which allows
electron transfer to Eu3+ (Ered ) -0.6 V vs SCE)41 to
occur. This conclusion is supported by the fact that the
fluoresence of 10b is quenched to a much lesser degree
by Tb3+ (see Figure 3b). Tb3+ is very hard to reduce (Ered
luminescent lifetime for Eu(10b) is 0.11 and 0.14 ms in
aerated and deoxygenated aqueous solutions, respec-
tively. These lifetimes are shorter than those observed
previously for calix[4]arene/Eu3+ complexes in methanol
(0.23-1.3 ms),18,19 thus demonstrating the stronger
quenching ability of water. However, the present lumi-
nescence lifetimes are also certainly useful in schemes
employing time-gated emission measurements to sup-
press the influence of the general background fluores-
cence of biological material, which usually has a lifetime
in the nanosecond region.
) -3.9 V vs SCE)41 and also very hard to oxidize (Eox
)
2.9 V vs SCE),41 making photoinduced electron transfer
1
between Tb3+ and chrysene* impossible.
We have reported previously on sensitized lumines-
cence of calix[4]arene/lanthanide complexes containing
an antenna chromophore attached to the lower rim of the
calixarene cage, to a complexed lanthanide ion, and
employing three carboxylic acid groups as the complexing
moieties, which resulted in overall neutral lanthanide
complexes.18,19 Depending on the chromophore used,
excitation wavelengths up to 350 nm could be achieved.
However, these complexes could only be studied in
organic solvents (e.g., methanol) because of their insolu-
bility in aqueous media.
While the 2-pyridyl disulfide group in 10a only allows
short wavelength excitation, it can be used as a coupling
reagent toward SH functionalities in biological material.
Con clu sion s
We have developed a facile route to neutral, water-
soluble calix[4]arene-based lanthanide complexes. More-
over, our approach has the potential for variation of
substituents in the carboxamido fragment at the lower
rim. Chrysene gave high energy transfer from a 1:1
complex ligand/Eu3+ at wavelengths extending to 363 nm.
Currently, we are investigating the possibility of intro-
ducing both a sensitizer and a handle for coupling to
biomolecules in the synthesis route.
The present lanthanide complexes combine long-
wavelength excitation (i.e., 10b) and overall electroneu-
trality with water solubility via introduction of substit-
uents at the upper rim of the calix[4]arene cage. The
(41) Morss, L. R. Chem. Rev. 1976, 76, 827.

H2O-Soluble Neutral Calix[4]arene-Lanthanide Complexes
J . Org. Chem., Vol. 62, No. 13, 1997 4233
25,26,27-T r is [(e t h o x y c a r b o n y l)m e t h o x y ]-28-[(h y -
d r oxyca r bon yl)m eth oxy]ca lix[4]a r en e (5a ) was prepared
similarly to a literature procedure for the p-tert-butylcalix[4]-
arene analogue:19 white solid; yield 91%; mp 65-66 °C; 1H
NMR δ 7.13 (d, 4 H, J ) 8.3 Hz), 7.0-6.8 (m, 2 H), 6.6-6.5
(m, 2 H), 6.5-6.4 (m, 4 H), 4.90 (d, 2 H, J ) 15.0 Hz), 4.90,
4.85 (s, 4 H), 4.8-4.6 (m, 4 H), 4.40 (d, 2 H, J ) 15.9 Hz),
4.3-4.2 (m, 6 H), 3.33 (d, 2 H, J ) 12.5 Hz), 3.30 (d, 2 H, J )
12.5 Hz), 1.31 (t, 9 H, J ) 8.3 Hz); FAB mass spectrum m/z
764.0 ([M + Na]+, calcd 764.3), m/z 739.5 (M+, calcd 739.3).
Anal. Calcd for C42H44O12: C, 68.10; H, 5.99. Found: C, 67.80;
H, 5.95.
Exp er im en ta l Section
Syn th esis. Gen er a l P r oced u r e. Melting points are
uncorrected. 1H NMR and 13C NMR spectra were recorded in
CDCl3 with Me4Si as the internal standard unless stated
otherwise. Preparative column chromatography separations
were performed on Merck silica gel 60 (230-400 mesh), while
precoated silica gel plates (Merck, 60 F254) were used for
analytical TLC. FAB mass spectra were performed with
m-nitrobenzyl alcohol as a matrix unless stated otherwise.
CHCl3, used in the chlorosulfonylation reaction, was flushed
over an Al2O3 column and dried on molecular sieves (4 Å). All
other chemicals were analytically pure and were used without
further purification. Hexane refers to the fraction with bp 40-
60 °C. All reactions were carried out under an argon atmo-
sphere. Standard workup means that the organic layers were
finally washed with water, dried over magnesium sulfate
(MgSO4), filtered, and concentrated in vacuo. The presence
of solvents in the analytical samples was confirmed by 1H NMR
spectroscopy or potentiometric titrations. Fast atom bombard-
ment (FAB) mass spectrometry for the water-soluble calix[4]-
arenes 10a ,b was carried out in a matrix solution (glycerol,
thioglycerol, m-nitrobenzyl alcohol) onto a stainless steel probe
and bombarded with xenon atoms with an energy of 3 KeV.
During the high-resolution FRIT-FAB measurements a resolv-
ing power of 10.000 (10% valley definition) was used. Cesium
iodide and/or glycerol were used to calibrate the mass spec-
trometer. S-(2-Pyridylthio)cysteamine hydrochloride,32 de-tert-
butylated calix[4]arene, and calix[4]arene tetraethyl ester were
prepared according to literature procedures.42
25,26,27-Tr is[(et h oxyca r b on yl)m et h oxy[-28-[[(2,2,2-
tr ich lor oeth oxy)ca r bon yl]m eth oxy]ca lix[4]a r en e (5c). To
a solution of triester monoacid 5a (4.49 g, 6.9 mmol) in dry
CH2Cl2 (75 mL) was added oxalyl chloride (5 mL), and the
resulting reaction mixture was refluxed for 1 h. The solvent
and excess of oxalyl chloride were removed in vacuo, where-
upon 2,2,2-trichloroethanol (1.05 g, 7.0 mmol) and triethy-
lamine (2.1 g, 20.8 mmol) were added. The mixture was
stirred overnight at rt. Water (75 mL) was added, followed
by standard workup. The crude product was separated by
column chromatography (CH2Cl2/hexane 3/1) to give 5c as a
1
white solid: yield 96%; mp 124-125 °C; H NMR δ 6.7-6.5
(m, 6 H), 6.47 (s, 6 H), 4.90 (s, 2 H), 4.89-4.65 (m, 4 H), 4.75,
4.70 (s, 4 H), 4.61 (d, 4 H, J ) 6.7 Hz), 4.2-4.0 (m, 6 H), 3.18
(d, 2 H, J ) 12.5 Hz), 3.17 (d, 2 H, J ) 12.5 Hz), 1.3-1.2 (m,
9 H); FAB mass spectrum m/z 895.1 ([M + Na]+, calcd 895.2).
Anal. Calcd for C44H45Cl3O12: C, 60.59; H, 5.20. Found: C,
60.51; H, 5.19.
Ch r ysen e-6-ca r boxa ld eh yd e (1b). To a solution of chry-
sene (1a ) (2.0 g, 8.76 mmol) and freshly distilled TiCl4 (3.30
g, 17.4 mmol) in dry CH2Cl2 (75 mL) was added dropwise bis-
(chloromethyl) ether (10.0 g, 86.8 mmol) at -10 °C. The
reaction mixture was stirred at rt for 30 min. The reaction
was quenched by the addition of crushed ice (15 g). The
organic layer was washed with 2 M HCl (2 × 100 mL), followed
by standard workup. The crude reaction product was purified
by flash column chromatography (CH2Cl2/hexanes, 50:50). The
product was crystallized from CH2Cl2/hexane to obtain a yellow
colored solid: yield 71%; mp 165-168 °C (lit.36 mp 164-166
°C).
6-(Hyd r oxym et h yl)ch r ysen e (1c). To a solution of 1b
(1.0 g, 3.9 mmol) in dry THF (75 mL) was added BH3‚THF (3
mL, 1.0 M solution) at 0 °C. The cooling bath was removed,
and the solution was stirred for 2 h at rt. HCl (1 M, 75 mL)
was added, and the precipitate was filtered off. The product
was triturated with CH2Cl2 to give pure 1c: yield 94%; mp
200-203 °C (lit.35 mp 200-202 °C).
6-(P h th a lim id om eth yl)ch r ysen e (1e). To a solution of
1d (0.50 g, 1.56 mmol) in DMF (25 mL) was added potassium
phthalimide (0.32 g, 1.72 mmol). The solution was stirred for
5 h at 50 °C. The solvent was removed in vacuo and the
residue dissolved in CH2Cl2 (50 mL) and washed with 0.1 M
NaOH (3 × 50 mL). The product was obtained as a white solid
in quantitative yield: mp 243-245 °C; 1H NMR (DMSO-d6) δ
9.1-9.0 (m, 1 H), 8.91 (d, 1 H, J ) 8.4 Hz), 8.86 (s, 1 H), 8.84
(d, 1 H, J ) 8.4 Hz), 8.5-8.4 (m, 1 H), 8.2-8.1 (m, 2 H), 8.0-
7.86 (m, 4 H), 7.86-7.7 (m, 4 H); 13C NMR (DMSO-d6) δ 166.28
(s), 42.69 (t); mass spectrum (EI) m/z 387.1 (M+, calcd for
C27H17NO2 387.1).
6-(Am in om eth yl)ch r ysen e (1f). A solution of 1e (0.50 g,
1.29 mmol) and hydrazine monohydrate (0.32 g, 6.46 mmol)
in EtOH (50 mL) was refluxed for 2 h. The solvent was
removed in vacuo, and H2O (50 mL) and CH2Cl2 (50 mL) were
added to the residue. The organic layer was washed with
NaHCO3 (saturated aqueous solution, 50 mL), followed by
standard workup: yield 95%; mp 204-206 °C; 1H NMR δ 8.84
(d, 2 H, J ) 8.3 Hz), 8.73 (d, 1 H, J ) 7.5 Hz), 8.70 (d, 1 H, J
) 7.5 Hz), 8.22 (d, 1 H, J ) 7.5 Hz), 8.00 (d, 2 H, J ) 8.3 Hz),
7.8-7.5 (m, 4 H), 4.52 (s, 2 H), 1.69 (broad s, 2 H); 13C NMR
δ 44.79; mass spectrum (EI) m/z 257.2 (M+, calcd 257.1). Anal.
Calcd for C19H15N‚0.4H2O: C, 86.26; H, 5.72; N, 5.29. Found:
C, 86.20; H, 5.49; N, 5.12.
5,11,17,23-T e t r a k is (c h lo r o s u lfo n y l)-25,26,27-t r is -
[(eth oxyca r bon yl)m eth oxy]-28-[[(2,2,2-tr ich lor oeth oxy)-
ca r bon yl]m eth oxy]ca lix[4]a r en e (6). To a solution of
trichloroethyl ester calix[4]arene 5c (5.0 g, 5.7 mmol) in CH2-
Cl2 (100 mL) was added dropwise HSO3Cl (18.7 mL, 0.23 mol)
at -10 °C. When the addition was complete, the cooling bath
was removed, and the reaction mixture was stirred at rt for 3
h. The solution was poured into a separation funnel filled with
crushed ice (50 g). To the white suspension formed was added
CH2Cl2 (100 mL), and the layers were allowed to separate for
24 h. The organic layer was concentrated, and the residue
was purified by flash column chromatography (CH2Cl2/ethyl
acetate (or THF), 90/10) to afford pure 6 as a white solid: yield
81%; mp 95-97 °C; 1H NMR δ 7.60 (s, 2 H), 7.59 (s, 2 H), 7.27
(s, 4 H), 5.15 (d, 2 H, J ) 12.5 Hz), 5.11 (d, 2 H, J ) 12.5 Hz),
4.92 (s, 2 H), 4.81 (s, 6 H), 4.5-4.1 (m, 8 H), 3.55 (d, 2 H, J )
12.5 Hz), 3.52 (d, 2 H, J ) 12.5 Hz), 1.4-1.2 (m, 9 H); FAB
mass spectrum m/z 1289.4 ([M + Na]+, calcd 1289.2). Anal.
Calcd for C44H41Cl7O20S4: C, 41.74; H, 3.26. Found: C, 41.82;
H, 3.21.
5,11,17,23-T e t r a k is [[[[[[t r is [[(t er t -b u t y ld im e t h y l-
s ily l)o x y ]m e t h y l]m e t h y l]a m in o ]c a r b o n y l]m e t h y l]-
a m in o]su lfon yl]-25,26,27-tr is[(eth oxyca r bon yl)m eth oxy]-
2 8 -[[(2 ,2 ,2 -t r i c h l o r o e t h o x y )c a r b o n y l ]m e t h o x y ]-
ca lix[4]a r en e (7). To a solution of tetrasulfonyl calix[4]arene
6 (1.62 g, 1.3 mmol) was added dropwise a mixture of amine
3 (3.30 g, 6.3 mmol) and triethylamine (0.92 g, 9.1 mmol). The
solution was stirred overnight. The solution was washed with
1 M HCl (50 mL) followed by standard workup. The crude
solid was purified by column chromatography (CH2Cl2/ethyl
acetate 97/3) to give 7 as a white solid: yield 79%; mp 102-
104 °C; 1H NMR δ 7.36 (broad s, 4 H), 6.72 (broad s, 2 H),
6.65 (broad s, 2 H), 6.48 (broad s, 4 H), 5.05 (broad s, 2 H)
5.0-4.6 (m, 12 H), 4.18 (q, 6 H, J ) 6.7 Hz), 3.81 (broad s, 24
H), 3.4-3.1 (m, 12 H), 1.3-1.2 (m, 9 H), 0.83 (s, 108 H), 0.00
(s, 72 H); FAB mass spectrum m/z 3226.0 ([M + Na]+, calcd
3226.4). Anal. Calcd for C140H261Cl3N8O36S4Si12‚H2O: C,
52.16; H, 8.24; N, 3.48. Found: C, 52.02; H, 8.21; N, 3.45.
5,11,17,23-T e t r a k is [[[[[[t r is [[(t er t -b u t y ld im e t h y l-
silyl)oxy]m eth yl]m eth yl]am in o]car bon yl]m eth yl]am in o]-
su lfon yl]-25,26,27-tr is[(eth oxycar bon yl)m eth oxy]-28-[[[[2′-
(p yr id in ed it h io)et h yl]a m in o]ca r b on yl]m et h oxy]ca lix-
[4]a r en e (8a ). A solution of 7 (0.65 g, 0.2 mmol), S-(2-
pyridylthio)cysteamine (2) (0.17 g, 0.2 mmol), triethylamine
(0.03 g, 0.2 mmol), and DBU (0.28 g, 1.8 mmol) in acetonitrile
(50 mL) was heated at 40 °C for 30 min. After removal of the
(42) Gutsche, C. D.; Lin, L.-G. Tetrahedron 1986, 42, 1633.

4234 J . Org. Chem., Vol. 62, No. 13, 1997
Steemers et al.
F igu r e 4. Corrected emission spectra of Eu(10a ) (- - -; λex ) 250 nm) and Eu(10b) (aerated: ‚‚‚; deoxygenated: s; λex ) 363 nm)
in Tris-HCl buffer (pH 8.0) at room temperature.
solvent, the residue was dissolved in CH2Cl2 (50 mL) and the
solution washed with 1 M HCl (50 mL), followed by standard
workup. After column chromatography (silica gel saturated
with NaCl, ethyl acetate), the product was obtained as a
slightly yellow solid: yield 67%; mp 95-98 °C; 1H NMR δ 8.43
(t, 1 H, J ) 4.2 Hz), 8.05 (broad s, 1 H), 7.7-7.5 (m, 3 H),
7.4-7.1 (m, 8 H), 6.69 (broad s, 4 H), 6.58 (broad s, 4H), 5.0-
4.6 (m, 16 H), 4.22 (q, 6 H, J ) 8.3 Hz), 3.81 (s, 24 H), 3.69 (m,
2 H), 3.4-3.1 (m, 12 H), 2.99 (t, 2 H, J ) 6.7 Hz), 1.3-1.2 (m,
9 H), 0.83 (s, 108 H), 0.00 (s, 72 H); FAB mass spectrum
5,11,17,23-T e t r a k is [[[[[[t r is [[(t er t -b u t y ld im e t h y l-
silyl)oxy]m eth yl]m eth yl]am in o]car bon yl]m eth yl]am in o]-
su lfon yl]-25,26,27-t r is[(h yd r oxyca r b on yl)m et h oxy]-28-
[[[[2′-(p yr id in ed it h io)et h yl]a m in o]ca r b on yl]m et h oxy]-
ca lix[4]a r en e (9a ): yield 98%; mp 143-144 °C. Anal. Calcd
for C139H256N10O35S6Si12: C, 52.89; H, 8.17; N, 4.44. Found:
C, 52.87; H, 8.34; N, 4.30.
5,11,17,23-T e t r a k is [[[[[[t r is [[(t er t -b u t y ld im e t h y l-
silyl)oxy]m eth yl]m eth yl]am in o]car bon yl]m eth yl]am in o]-
su lfon yl]-25,26,27-t r is[(h yd r oxyca r b on yl)m et h oxy]-28-
[[[(9-ch r ysen em eth yl)a m in o]ca r bon yl]m eth oxy]ca lix[4]-
a r en e (9b): yield 97%; mp 160-162 °C. Anal. Calcd for
C151H261N9O35S4Si12‚3.5H2O: C, 55.10; H, 8.11; N, 3.83.
Found: C, 54.80; H, 8.10; N, 3.72.
Gen er a l P r oced u r e for th e P r ep a r a tion of Wa ter -
Solu ble Ca lix[4]a r en es 10a ,b. A solution of triacid calix-
[4]arenes 9a ,b (0.5 g) in trifluoroacetic acid (TFA)/H2O (9/1,
25 mL) was stirred overnight, whereupon toluene (50 mL) was
added. The solution was concentrated in vacuo. Again,
toluene (50 mL) was added, and the mixture was concentrated
in vacuo. This procedure was repeated three times. The crude
white solid was dissolved in a minimum amount of H2O (5 mL).
To this solution was added dropwise acetonitrile (10a ) or
acetone (10b) until the product started to precipitate. After
the suspension was stirred for 30 min, the product was filtered.
The product was freeze-dried and analyzed. Prior to the
luminescence measurements, solutions of compounds 10a ,b in
water were dialyzed (benzoylated cellulose membrane) to
remove excess trifluoroacetic acid and again freeze-dried.
5,11,17,23-Tet r a k is[[[[[t r is[(h yd r oxym et h yl)m et h yl]-
am in o]car bon yl]m eth yl]am in o]su lfon yl]-25,26,27-tr is[(h y-
d r oxyca r bon yl)m eth oxy]-28-[[[[2′-(p yr id in ed ith io)eth yl]-
a m in o]ca r bon yl]m eth oxy]ca lix[4]a r en e (10a ). The crude
solid was triturated with EtOAc/H2O to obtain pure 10a : yield
99%; during melting point determination the compound de-
composed; 1H NMR (400 MHz, D2O, 50 °C) δ 8.57 (s, 1 H),
8.0-7.9 (m, 3 H), 7.8-7.2 (m, 8 H), 5.4-4.9 (m, 12 H), 4.6-
4.4 (m, 8 H), 4.2-3.6 (m, 24 H), 3.40 (t, 2 H, J ) 7.4 Hz), 3.28
(d, 4 H, J ) 11.4 Hz), 1.50 (t, 2 H, J ) 7.4 Hz); FAB mass
spectrum (glycerol) m/z 1785.7 [M+, calcd 1785.8]. Anal. Calcd
for C67H88N10O35S6‚3TFA: C, 41.40; H, 5.20; N, 6.20. Found:
C, 41.27; H, 5.05; N, 6.31.
(ONPOE) m/z 3238.0 (M+, calcd 3237.5), 3128.6 ([M+
-
S-pyridine]). Anal. Calcd for C145H268N10O35S6Si12: C, 53.44;
H, 8.36; N, 4.30. Found: C, 53.30; H, 8.51; N, 4.17.
5,11,17,23-T e t r a k is [[[[[[t r is [[(t er t -b u t y ld im e t h y l-
silyl)oxy]m eth yl]m eth yl]am in o]car bon yl]m eth yl]am in o]-
su lfon yl]-25,26,27-tr is[(eth oxycar bon yl)m eth oxy]-28-[[[(9-
c h r y s e n e m e t h y l)a m in o ]c a r b o n y l]m e t h o x y ]c a lix [4]-
a r en e (8b) was prepared similarly as compound 8a starting
from the trichloroethyl ester 7 (1.65 g, 0.5 mmol), 6-(aminom-
ethyl)chrysene (1f) (0.15 g, 0.6 mmol) and DBU (0.71 g, 4.6
mmol). The crude solid was purified by column chromatog-
raphy (silica gel saturated with NaCl, ethyl acetate/CH2Cl2
1
5/95): yield 63%; mp 115-117 °C; H NMR δ 8.8-8.7 (m, 3
H), 8.66 (d, 1 H, J ) 9.3 Hz), 8.17 (d, 1 H, J ) 7.5 Hz), 8.09
(broad s, 1 H), 8.0-7.9 (m, 2 H), 7.8-7.5 (m, 4 H), 7.4-7.2 (m,
4 H coincides with CDCl3), 6.8-6.5 (m, 8 H), 6.40 (broad s, 4
H), 5.20 (d, 2 H, J ) 6.2 Hz), 4.9-4.4 (m, 12 H), 4.07 (q, 6 H,
J ) 7.2 Hz), 3.81 (broad s, 24 H), 3.4-3.2 (broad s, 12 H), 1.08
(t, 9 H, J ) 7.1 Hz), 0.85 (s, 108 H), 0.01 (s, 72 H); FAB mass
spectrum m/z 3333.6 ([M - H]+, calcd 3333.6). Anal. Calcd
for C157H273N9O35S4Si12‚2H2O: C, 56.32; H, 8.34; N, 3.76.
Found: C, 55.93; H, 8.41; N, 3.58.
Gen er a l P r oced u r e for th e P r ep a r a tion of Tr ia cid
Ca lix[4]a r en es 9a ,b. To a solution of 8a ,b (5 mmol) in
MeOH/H2O 5/1 (50 mL) and a minimum amount of THF, for
solubility reasons, was added K2CO3 (50 mmol). After the
solution was refluxed for 15 min, CH2Cl2 (50 mL) was added,
and the solution was acidified with 1 M HCl to pH 7. The
aqueous layer was extracted with CH2Cl2 (2 × 50 mL). The
combined layers were dried over MgSO4, filtered, and concen-
trated in vacuo to give the pure products.
The characterization of the derivatives 9a ,b with 1H NMR
spectroscopy was difficult because of line broadening. Ad-
ditionally, the relative intensity of the 1H CH3-resonances
(TBDMS) compared to the other 1H-resonances is large. No
satisfactory mass spectrum (FAB and FRIT-FAB) could be
obtained for the triacid derivatives 9a ,b. Therefore, charac-
terization was done by melting point determination and
elemental analysis.
5,11,17,23-Tet r a k is[[[[[t r is[(h yd r oxym et h yl)m et h yl]-
a m in o]ca r b on yl]m et h yl]a m in o]su lfon yl]-25,26,27-t r is-
[(h yd r oxyca r bon yl)m eth oxy]-28-[[[(9-ch r ysen em eth yl)-
a m in o] ca r bon yl]m eth oxy]ca lix[4]a r en e (10b). The crude
solid was triturated with ethyl acetate/H2O to obtain 10b as
a white pure solid: yield 99%; during melting point determi-
nation the compound decomposed; 1H NMR (D2O, 80 °C) δ 9.0-

H2O-Soluble Neutral Calix[4]arene-Lanthanide Complexes
J . Org. Chem., Vol. 62, No. 13, 1997 4235
7.2 (m, 19 H), 5.4-4.8 (m, 18 H), 4.69 (broad s, 24 H), 3.82 (d,
4 H, J ) 9.3 Hz), 3.27 (d, 4 H, J ) 11.5 Hz); FAB mass
spectrum (glycerol) m/z 1857.8 [(M + H)+, calcd 1856.8]; exact
FRIT-FAB m/z 1856.4735 [M+, calcd 1856.4761], the fragmen-
tation pattern corresponds with the proposed structure. Anal.
Calcd for C79H93N9O35S4‚4TFA: C, 45.10; H, 4.01; N, 5.43.
Found: C, 45.18; H, 4.23; N, 5.45.
of about 0.5 µs relative to the laser pulse maximum, and 50
µs increment delay between spectra. At each delay, spectra
were averaged over 50 laser shots to improve the signal to
noise ratio. From these data, luminescent lifetimes were
calculated by fitting the wavelength integrated signal in time.
Monoexponential decay was observed in all cases.
All measurements were done in Tris-HCl buffer (0.05 M,
pH 8.0).
Lu m in escen ce Mea su r em en ts. Continuous emission and
excitation spectra were recorded on
a Spex Fluorolog 2
spectrofluorimeter. Figure 4 gives representative results of
such spectra.
Ack n ow led gm en t. The research described in this
paper was supported by the Technology Foundation
(S.T.W.), Technical Science Branch of the Netherlands
Organization for Scientific Research (NWO).
Time-resolved emission spectra were obtained using a
Lumonics EX700 XeCl excimer laser (308 nm) as excitation
source. The resulting luminescence was observed by a gated,
intensified CCD camera from Princeton Instruments. Spectra
were taken with a typical gatewidth of 25 µs, an initial delay
J O970132J