Bis(metallo) capsules based on two ionic diphosphines

Article abstract of DOI:10.1002/asia.201100073

Self-assembly and characterization of heterodimeric diphosphine capsules formed by multiple ionic interactions are described. The first type of capsules is composed of one novel tetrasulfonato-xantphos ligand and one complementary tetraammonium calix[4]arene. Encapsulation of a transition metal is achieved by self-assembly of a rhodium complex containing the tetraanionic diphosphine ligand and a tetracationic calix[4]arene. The second type of capsules is composed of two oppositely charged diphosphine ligands: one tetrasulfonato- xantphos and one tetraammonium-diphosphine (of the xantphos-, DPEphos-, and 1,2-bis(diphenylphosphino)ethane (dppe)-type). Bis(metallo) capsules, that is, simultaneous encapsulation of two different transition metals, are created by self-assembly of a palladium or platinum complex containing a tetracationic ligand and a rhodium complex containing a tetraanionic ligand. Diphosphine ligands with different flexibilities and shapes assemble into metallocapsules with a proper capsular structure, as is indicated by ¹H NMR and 1D-NOESY spectroscopy, ESIMS, and modeling studies. Copyright

Full text of DOI:10.1002/asia.201100073

DOI: 10.1002/asia.201100073
BisACTHUNRTGNEUNG(metallo) Capsules Based on Two Ionic Diphosphines
Tehila S. Koblenz,[a] ing. Henk L. Dekker,[b] Chris G. de Koster,[b]
Piet W. N. M. van Leeuwen,[a] and Joost N. H. Reek*[a]
Abstract: Self-assembly and characteri-
oppositely charged diphosphine li-
gands: one tetrasulfonato-xantphos and
one tetraammonium-diphosphine (of
the xantphos-, DPEphos-, and 1,2-bis(-
ferent transition metals, are created by
zation of heterodimeric diphosphine
capsules formed by multiple ionic inter-
actions are described. The first type of
capsules is composed of one novel tet-
rasulfonato-xantphos ligand and one
complementary tetraammonium cal-
ix[4]arene. Encapsulation of a transi-
tion metal is achieved by self-assembly
of a rhodium complex containing the
tetraanionic diphosphine ligand and a
tetracationic calix[4]arene. The second
type of capsules is composed of two
self-assembly of a palladium or plati-
num complex containing a tetracationic
ligand and a rhodium complex contain-
ing a tetraanionic ligand. Diphosphine
ligands with different flexibilities and
shapes assemble into metallocapsules
with a proper capsular structure, as is
diphenylphosphino)ethane
(dppe)-
type). Bis(metallo) capsules, that is, si-
AHCTUNGTRENNUNG
multaneous encapsulation of two dif-
1
indicated by H NMR and 1D-NOESY
Keywords: calixarenes · ionic inter-
actions · phosphine ligands · supra-
spectroscopy, ESIMS, and modeling
studies.
molecular capsules
metals
·
transition
Introduction
for metal encapsulation that involves a bifunctional diphos-
phine ligand containing a donor-atom site for metal com-
plexation and functional groups for capsule formation.[4]
Self-assembly of a tetracationic diphosphine ligand, or the
transition-metal complex thereof, with a tetraanionic cal-
ix[4]arene resulted in capsule formation and metal encapsu-
lation (Scheme 1a). The transition-metal complex is an inte-
grated part of the capsule with the transition metal located
inside the capsule. As it is not involved in the assembly pro-
cess it is available for catalytic transformations. We report a
new type of capsules that is composed of two oppositely
charged diphosphine ligands or the transition-metal com-
plexes thereof (Scheme 1b). The novel hetero bis(diphos-
Supramolecular chemistry concerns the application of pro-
grammed molecules that assemble via intermolecular nonco-
valent bonds into larger molecular architectures, such as mo-
lecular capsules.[1] The novel finite microenvironment within
nanocapsules and their reversible encapsulation properties
have stimulated their application as nanoreactors.[2] Encap-
sulation of a transition metal within these nanoreactors re-
sulted in new selectivities and activities for the transition-
metal catalyst.[3] We introduced a template-ligand approach
[a] Dr. T. S. Koblenz, Prof. Dr. P. W. N. M. van Leeuwen,
Prof. Dr. J. N. H. Reek
Homogeneous and Supramolecular Catalysis
Vanꢀt Hoff Institute for Molecular Sciences
University of Amsterdam
Postbox 94720, 1090 GS Amsterdam (The Netherlands)
Fax : (+31)020-5255604
E-mail: J.N.H.Reek@uva.nl
[b] i. H. L. Dekker, Prof. Dr. C. G. de Koster
Mass Spectrometry of Biomacromolecules
Swammerdam Institute for Life Sciences
University of Amsterdam
Postbox 94720, 1090 GS Amsterdam (The Netherlands)
Supporting information for this article, including ESIMS measured
and calculated isotope patterns of the capsules, is available on the
WWW under http://dx.doi.org/10.1002/asia.201100073.
Scheme 1. Schematic picture of a metallodiphosphine and calix[4]arene-
based capsule (a) and a bis(metallodiphosphine) capsule (b).
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FULL PAPERS
phine) capsule can simultaneously encapsulate two different
transition metals within its cavity to give a bis
sule.
ACHTUNGTREN(NUNG metallo) cap-
Results and Discussion
Synthesis
For the anionic part of the capsules a sulfonated diphos-
phine will be used. Water-soluble sulfonated phosphine li-
gands have been applied in two-phase catalysis and in aque-
ous-phase catalysis, for example, the rhodium–TPPTS (triso-
dium salt triphenylphosphine trisulfonate) catalyst for the
hydroformylation of propene in water.[5a–c] Xantphos-type li-
gands with sulfonato groups have also been reported, for ex-
ample, sulfoxantphos, which contains two sulfonato groups
on the xanthene backbone, and the aggregating amphiphilic
xantphos in which the four arylphosphines are substituted
with a para-sulfonatophenyl separated by a bridge of ali-
phatic carbon atoms.[5b–e]
We synthesized a novel tetraanionic xantphos-type ligand
by direct sulfonation of the four arylphosphine rings. The
precursor tetrakis(2-methoxyphenyl)-xantphos x is prepared
by a reaction of the lithiated product of 2-bromoanisole
with 4,5-bis(diethoxyphosphonito)-9,9-dimethylxanthene in
22% yield (Scheme 2a).[6] Sulfonation of the arylphosphine
rings of x was achieved by a reaction with concentrated sul-
furic acid. Hydrolysis of the reaction mixture with water re-
sulted in tetrakis(2-methoxy-5-sulfonicacid-phenyl)-xantphos
a’ (Scheme 2b). We observed that a’ (partly) precipitates
from the reaction mixture as a sticky white solid at tempera-
tures lower than À208C but immediately redissolves at
higher temperatures. Consequently, isolation of the tetraacid
by filtration was not successful.[7a] Neutralization of the reac-
tion mixture by sodium hydroxide and product extraction
with methanol afforded tetrakis(2-methoxy-5-sulfonatophen-
Scheme 2. Synthesis of tetrakis(2-methoxyphenyl)-xantphos x (a), tetra-
kis(2-methoxy-5-sulfonicacid-phenyl)-xantphos a’ and tetrakis(2-me-
thoxy-5-sulfonatophenyl)-xantphos tetrasodiumsalt a (b).
tion occurred exclusively on the arylphosphine rings para to
the 2-methoxy substituent and meta to the phosphorus
atom, as is confirmed by 1H NMR, H-H-COSY, and
13P{1H} NMR spectroscopy. No sulfonation of the xanthene
backbone is observed under the conditions applied and,
therefore, no alkyl groups at the 2- and 7-position of the
xanthene backbone were necessary.[5c,7a] The resonances in
the 13P{1H} NMR spectrum of the tetrasulfonicacid-xantphos
a’ (d=À25.6 ppm) are downfield-shifted relative to the reso-
nance of the sodium salt a (d=À34.8 ppm). This downfield
shift indicates that the phosphorus atoms of a’ are protonat-
ed, which is a result of the acidic environment or the bis(z-
witterionic) nature of a’, as was previously reported by Mul
and co-workers.[7] During the reaction, the phosphorus
atoms were protected as phosphonium salts by protonation
and indeed no phosphine oxide was formed.
yl)-xantphos tetrasodium salt
a in 74% yield (Sche-
me 2b).[5b–c,7b] An attempt was made to remove the trace
amounts of sodium sulfate salts from the product by re-
verse-phase silica chromatography (eluents: water/ethanol).
The salt rests were removed but the diphosphine was oxi-
dized during column chromatography because no air-free
conditions were used (in reverse-phase silica chromatogra-
phy the solvent flow is restricted and, therefore, a pump or
pressurized gas is required to drive the solvent through the
column). Consequently, the tetrasulfonato-xantphos a con-
tained trace amounts of sodium sulfate salts. All new com-
pounds described here have
Reaction of rhodium(I) dimer [RhACTHNUTRGNEU(GN m-Cl)(CO)2]2 with two
equivalents of tetraanionic diphosphine a in methanol re-
sulted in the formation of the corresponding RhI carbonyl
chloride complex [Rh(a)Cl(CO)] (1a) (Scheme 3). The bi-
dentate ligand a of the distorted square-planar RhI-complex
been characterized by NMR
spectroscopy, IR spectroscopy,
and mass spectrometry tech-
niques (see the Experimental
Section).
Methoxy groups are ortho-
and para-directing groups in
electrophilic aromatic substitu-
tion reactions. Indeed, sulfona- Scheme 3. Synthesis of trans-[Rh(a)Cl(CO)] (1a).
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BisACHTUNGTRENNUNG(metallo) Capsules Based on Two Ionic Diphosphines
1a coordinates to the rhodium atom in a trans fashion, as is
indicated by 31P{1H} NMR spectroscopy: d=22.7 ppm (d),
J
A Metallocapsule Based on One Diphosphine and One
Calix[4]arene
RhP =130.6 Hz.[8] The tetracationic tetrakis(ammoniumchlor-
ide) calix[4]arene z was synthesized by N protonation of
We have previously reported metallocapsules composed of
one tetracationic diphosphine, or the transition-metal com-
plex thereof, and one tetraanionic calix[4]arene.[4] We were
interested to know if capsules composed of one tetraanionic
diphosphine, or the transition-metal complex thereof, and
one tetracationic calix[4]arene will also be formed. The ex-
periments below describe the diphosphine capsule z·a, which
is composed of the tetraanionic xantphos-type diphosphine
a and the tetracationic calix[4]arene z, and metallocapsule
z·1a, which is composed of the rhodium complex 1a con-
taining the tetraanionic ligand and z (Figure 1). Encapsula-
tion of a transition metal within capsule z·a is achieved by
using the rhodium complex 1a.
tetrakisACHTUNGTRENNUNG(amino) calix[4]arene by HCl in diethyl ether
(Scheme 4).[9]
Scheme 4. Synthesis of tetraammonium-calix[4]arene z.
Self-Assembly
Characterization
1
All heterodimeric capsules reported here are formed by
ionic interactions and are composed of one tetraanionic
building block and one complementary tetracationic build-
ing block. Self-assembly of these capsules is simply achieved
by mixing methanol solutions containing these building
blocks (Scheme 5). The tetracationic building block p, that
The H NMR spectra of capsules z·a and z·1a in CD3OD at
208C show sharp resonances, with the exception of the
broad singlet resonance of the aromatic protons of the cal-
ix[4]arene z (Figure 2). Capsules z·a and z·1a show signifi-
cant upfield shifts for the aromatic proton of z, with respect
to that of the corresponding free z: Ddz·a =0.42 and Ddz·1a
=
0.21 ppm. The observed upfield
shifts are likely caused by inter-
action with the sulfonato
groups of a and 1a and support
capsule formation. Additional
evidence for capsule formation
and their stabilities in the gas
phase is obtained by ESIMS.[10]
The ESIMS spectra of capsules
z·a and z·1a in CH3OH show
prominent ion peaks of the cap-
sules at m/z: 892.83 for
[z·a+2H]2+ and 957.80 for
[z·1aÀCl+H]2+ (see Figure 3,
the Experimental Section, and
Scheme 5. Self-assembly of ionic-based supramolecular capsule p·n (schematic picture).
is, [p]4+
N
the Supporting Information). All the capsules ion peaks cor-
respond to 1:1 complexes and no ion peaks for higher aggre-
gates were detected.
is, [n]
ACHTUNGTRENNUNG
p·n and four equivalents of the sodium chloride salt. The
capsules are formed instantaneously and are in equilibrium
with the building blocks in monomeric form containing the
original counter ions. Formation of all the capsules de-
scribed here is evidenced by proton NMR spectroscopy and
by mass spectrometry (see the Experimental Section and
Supporting Information). Additional evidence for the for-
mation of capsules c·a and d·a is obtained by 1D-NOESY
measurements. A single set of proton resonances for the
free and associated building blocks was observed in the
1H NMR spectra for all the capsules described here. This in-
dicates a fast exchange process on the NMR timescale be-
tween the building blocks that are in the monomeric form
(free) and those in the capsular form (bound).
Molecular Modeling
The four negative charges of tetrasulfonato-xantphos a are
located at the meta-position of its arylphosphine rings and
the four positive charges of the calix[4]arene z are located
at the para-position of its aryl rings. The modeled structure
(PM3 level) of capsule z·a shows that the rigid tetrasulfona-
to-xantphos a and the rigid concave calix[4]arene z are com-
plementary in shape and that the 1:1 assembly has a highly
symmetrical capsular structure (Figure 1a). The methoxy
groups of a do not interfere with capsule formation. The
four aryl groups of a are situated perpendicularly to the cap-
sule equator with the sulfonato groups pointing down, and
the charges of a and z are arranged in an array around the
capsule equator. The structure of capsule z·a is similar to
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Figure 3. ESIMS spectrum of capsule z·1a in CH3OH (inset: measured
isotope pattern).
is located inside the capsule and the chloride and carbonyl
groups of 1a are sticking out of the capsule (Figure 1b).
Bis(diphosphine) Capsules
All capsules described by us so far are formed by ionic inter-
actions and are composed of one calix[4]arene and one di-
phosphine. Our next challenge is to form capsules composed
of two oppositely charged diphosphine ligands. To this end,
we studied the bis(diphosphine) capsules b·a, c·a, and d·a,
which are based on the tetraanionic diphosphine a and on a
tetracationic
tetrakis(para-diethylbenzylammoniumchlori-
Figure 1. Modeled and molecular structures of diphosphine capsule a) z·a
and b) metallocapsule z·1a. The NH hydrogen atoms are visible.
de)diphosphine with an ethylene (b) diphenyl ether (c), or
xanthene (d) backbone (Figure 4). The three tetracationic
diphosphines b, c, and d have different flexibilities and
shapes but all form a heterodimeric capsule with a concave
rigid tetrasulfonato calix[4]arene, as we previously report-
ed.[4] The xantphos-type ligand a is less rigid than calix[4]ar-
ene, and thus we were interested to know if this xantphos-
type ligand will form a 1:1 capsule with a second diphos-
phine that is equally or less rigid.
Characterization
1
The H NMR spectra of capsules b·a, c·a, and d·a in CD3OD
at 208C show significant upfield shifts for the diethylammo-
niummethyl substituents, CH2NH
to those of the corresponding free diphosphines b, c, and d:
Dd(CH2CH3)2 =0.21–0.23, Dd(CH2CH3)2 =0.31–0.35, Dd-
(CH2N)=0.34–0.39 ppm (see Figures 5 and 6 and the Sup-
+A
CHTUGNTRENN(UGN CH2CH3)3, with respect
Figure 2. 1H NMR spectra in CD3OD at 208C. Top: calix z, middle: cap-
sule z·a (z/a 1:2, [a]=4 mm), bottom: diphosphine a.
G
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
porting Information). The upfield shifts point to partial in-
clusion of the diethylammoniummethyl substituents inside
the hydrophobic cavity of the capsules.[4,11] The capsuleꢂs
proton resonances are relatively sharp. The 1D-NOESY
spectrum of the heterodimeric capsule c·a in CD3OD display
small but significant negative intermolecular NOE contacts
that of a capsule composed of a xantphos-m-anilinium and a
sulfonato calix[4]arene, previously described by us.[4b] Rho-
dium complex [Rh(a)Cl(CO)] (1a) adopts
a distorted
square-planar geometry with the ligand coordinating in a
trans fashion. The modeled structure (PM3 level) of the
metallocapsule z·1a illustrates that 1a and z fit nicely and
can form a capsule through interaction between the ammo-
nium and sulfonato groups. In addition, the rhodium metal
+A
between the NH CTHNUGTNRE(UNG CH2CH3)2 protons of c, and the aromatic
proton of a, that is, H6 of PAr2, upon selective saturation of
the methyl protons of c (Figure 7). Another NOE contact is
+A
observed between the NH CHTNUGTRNE(NGU CH2CH3)2 protons of c and the
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BisACHTUNGTRENNUNG(metallo) Capsules Based on Two Ionic Diphosphines
Figure 4. Modeled and molecular structures of the bis(diphosphine) capsules a) b·a, b) c·a, and c) d·a.
Figure 5. 1H NMR spectra in CD3OD at 208C. Top: diphosphine b, mid-
dle: capsule b·a (b/a 1:2, [a]=4 mm), bottom: diphosphine a. Asterisks in-
dicate solvent signals.
Figure 6. 1H NMR spectra in CD3OD at 208C. Top: diphosphine c, mid-
dle: capsule c·a (c/a 1:2, [a]=4 mm), bottom: diphosphine a. Asterisks in-
dicate solvent signals.
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Figure 7. 1D-NOESY spectrum of bis(diphosphine) capsule c·a in
CD3OD (c/a 1:2, [a]=4 mm; inset: 1D-NOESY spectrum enlargement).
Figure 9. ESIMS spectra: isolation of a) bis(diphosphine) capsule c·a and
b) collision-induced dissociation of capsule c·a (ESIMS/MS).
OMe group of a. This illustrates that the aryl substituents of
the two diphosphines are facing one another to form the di-
meric 1:1 capsular structure. The observed negative NOE
enhancements confirm the large size of the capsules.[12] For
the heterodimeric capsule d·a, similar NOE contacts are ob-
served.
Additional evidence for capsule formation and their sta-
bilities in the gas phase is obtained by ESIMS. The ESIMS
spectra of the bis(diphosphine) capsules b·a, c·a, and d·a in
CH3OH show prominent ion peaks of the capsules at m/z:
879.80 for [b·a+2H]2+, at 963.89 for [c·a+2H]2+, and at
969.82 for [d·a+2H]2+ (see Figure 8, the Experimental Sec-
tion, and the Supporting Information). All the capsuleꢂs ion
peaks correspond to 1:1 complexes and no ion peaks for
higher aggregates were detected. The assignment of the cap-
suleꢂs ion peaks is in agreement with the ESIMS/MS colli-
sion-induced dissociation, upon which the isolated capsuleꢂs
ion peak (partly) disappeared and product ion peaks ap-
peared that correspond to the capsule building blocks
(Figure 9).
Molecular Modeling
Self-assembly of capsules b·a, c·a, and d·a is primarily driven
by the formation of multiple intermolecular ionic interac-
tions between the oppositely charged diphosphine ligands.
The tetracationic diphosphines contain the same para-dieth-
ylbenzylammonium groups but have different backbones:
ethylene b, diphenyl ether c, and xanthene d. According to
modeling studies (PM3 level), the molecular sizes of b, c,
and d are similar to a, but their shapes and conformational
rigidity differ. The xantphos-type ligands a and d have a
rigid backbone and a concavelike structure, whereas dppe-
based b and DPEphos-based c have more flexible back-
bones and no concave structures.[4b] The modeled structures
of capsules b·a, c·a, and d·a show that the diphosphines are
facing one another and that their opposite charges are ar-
ranged in an array around the capsule equator (Figure 4).
The cavities of the capsules are defined by the eight phos-
phorus aryl rings. The rigid and concavelike xantphos-type
ligand a fixes the flexible diphosphines b and c into the
proper conformation needed to form a capsule. Hence, one
rigid building block is sufficient to form an ionic-based cap-
sule.[13] Interestingly, the free electron pairs on the phospho-
rus atoms of b·a are pointing away from the capsule, unlike
in c·a and d·a in which they are pointing to the capsuleꢂs in-
terior. To form the corresponding bis
ACHTUNGERTN(NUNG metallo) capsule, cap-
sule b·a will have to undergo a conformational change.
BisACTHNUTRGNEU(GN metallo) Capsules Based on Two Diphosphines
We described the encapsulation of one transition metal
within capsule z·a composed of a tetraanionic diphosphine a
and a tetracationic calix[4]arene z by using the correspond-
ing rhodium complex 1a. We anticipated that simultaneous
encapsulation of two transition metals in the bis(diphos-
phine) capsules would provide a new class of easily accessi-
ble bisACHTNUTRGNE(NUG metallo) capsules. Simultaneous encapsulation of
two metals can be achieved by mixing solutions of a transi-
tion-metal complex containing a tetraanionic diphosphine
Figure 8. ESIMS spectrum of bis(diphosphine) capsule c·a in CH3OH
(inset: isotope pattern).
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BisACHTUNGTRENNUNG(metallo) Capsules Based on Two Ionic Diphosphines
and a transition-metal complex containing a tetracationic di-
phosphine. We used the rhodium complex 1a as the tetraa-
nionic building block, and the palladium and platinum com-
plexes trans-[Pd(Br)(d)
(3d), and cis-[Pd(b)Cl2] (4b) as the tetracationic building
blocks.[4,14] The bis
(metallo) capsules 2d·1a and 4b·1a en-
ACHTUGNTREN(NUNG p-C6H4CN)] (2d), cis-[PtCl2(d)]
ACHTUNGTRENNUNG
capsulate one palladium atom and one rhodium atom, and
capsule 3d·1a encapsulates one platinum atom and one rho-
dium atom (Figure 10). Complexes 2d, 3d, and 4b contain
tetrakis(para-diethylbenzylammoniumchloride)-xantphos d-
4HCl, tetrakis(para-diethylbenzylammoniumtosylate)-xant-
phos d-4HOTs, and tetrakis(para-diethylbenzylammonium-
tosylate)-dppe b-4HOTs, respectively.
Characterization
Figure 11. 1H NMR spectra in CD3OD/CD2Cl2 (8:2 v/v) at 208C. Top:
palladium complex 2d, middle: capsule 2d·1a (2d/1a 1:2, [1a]=4 mm,
bottom: rhodium complex 1a. Asterisks indicate solvent signals.
The bisACHTUNGTRENNUNG(metallo) capsules hardly dissolve in methanol but
addition of 10–20% (v) of dichloromethane resulted in a
better solubility of the capsules. As can be seen in Figure 11,
the 1H NMR spectra of the bis
ACTHNUTRGNE(UNG metallo) capsules 2d·1a,
3d·1a, and 4b·1a in CD3OD/
CD2Cl2 (80:20 v) at 208C show
significant upfield shifts for the
diethylammoniummethyl sub-
+A
stituents, CH2NH CTHNUGTREN(NUG CH2CH3)3,
with respect to those of the cor-
responding free-metal com-
plexes 2d, 3d, and 4b: Dd-
A
Dd-
Dd-
(see
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
the Experimental Section).
These upfield shifts point to
partial inclusion of the diethy-
lammoniummethyl substituents
inside the hydrophobic cavity
of the capsules. Variable tem-
perature 1H NMR spectra of
the bis
line-broadening only for the
CH2N and N(CH2CH3)2 protons
ACHTUNGERTN(NUNG metallo) capsules show
AHCTUNGTRENNUNG
of 2d, 3d, and 4b at 208C and
sharper resonances for these
protons at higher temperatures
(40 and 608C).[4,11] Additional
evidence for capsule formation
and their stabilities in the gas
phase was obtained by ESIMS.
The ESIMS spectra of the bis-
A
capsules
2d·1a,
3d·1a, and 4b·1a in CH3OH
show prominent ion peaks of
the capsules at m/z: 759.52 for
[2d·1aÀBrÀCl+H]3+
,
754.53
for [3d·1aÀ3Cl]3+, and 664.52
for
[4b·1aÀ3Cl]3+
(see
Figure 12, the Experimental
Section, and the Supporting In-
Figure 10. Modeled and molecular structures of a) bisACTHUNTGRENNG(U metallo) capsules 2d·1a and b) 4b·1a.
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J. N. H. Reek et al.
FULL PAPERS
formation). All the capsule ion peaks correspond to 1:1
complexes and no ion peaks for higher aggregates were de-
tected.
with one another, that is, form a metal–metal bond. Howev-
er, interaction between, for example, a cationic metal center
and a cyanophenyl group (located inside the capsule) of the
second metal might be possible.
MonoACTHNUTRGNE(NUG metallo) Capsule Based on Two Diphosphines
We described the encapsulation of two transition metals
within a bis(diphosphine) capsule. Encapsulation of only
one transition metal within a bis(diphosphine) capsule can
also be achieved, for example, by mixing solutions of a tran-
sition-metal complex containing a tetracationic ligand and a
tetraanionic diphosphine. To this end, the formation of the
monoACTHNUGRTENNUG(metallo) capsule 2d·a based on trans-[Pd(Br)(d)ACHTUNGTRENNUNG(p-
C6H4CN)] (2d) and on the tetrasulfonato-xantphos ligand a
was studied (Scheme 6).
Figure 12. ESIMS spectrum of capsule 4b·1a in CH3OH (inset: isotope
pattern).
Molecular Modeling
According to modeling studies (PM3 level), in line with lit-
erature, the palladium complex [Pd(Br)(d)ACTHUNTRGNE(UNG p-C6H4CN)]
(2d) adopts a distorted square-planar geometry with the
oxygen atom of the xanthene backbone in the apical posi-
tion and the diphosphine ligand coordinated in a trans fash-
ion.[4a,15] The palladium dichloride complex [PdCl2(b)] (4b)
adopts a square-planar geometry with the diphosphine
ligand coordinated in a cis fashion.[4b,16] The modeled struc-
tures of the bisACHTUNGTRENNUNG(metallo) capsules 2d·1a and 4b·1a illustrate
that the Pd complexes 2d and 4b and the square-planar
trans-Rh-complex 1a fit nicely and are facing one another
(Figure 10). In each capsule, the two transition metals are
located inside the capsule. The chloride and carbonyl groups
of 1a and aryl and bromide groups of 2d are sticking out of
the capsule, whereas the two chlorides of 4b are pointing
into the capsuleꢂs interior. The modeled structures of the
Scheme 6. Molecular structure of mono
sulting capsules upon metal exchange.
ACHTUNGTRNE(NUNG metallo) capsule 2d·a and the re-
1H NMR Spectroscopic Study
1
As can be seen in Figure 13, top, the H NMR spectrum of
capsule 2d·a (at a 2d/a ratio of 1:2) shows significant upfield
shifts for the diethylammoniummethyl substituents,
bis
ACHTUNGTRENNUNG
two metals is 8.5 ꢃ for the bisAHCTNUGTRENNNUG
2d·1a and 4.9 ꢃ for the dppe- and xantphos-based capsule
4b·1a.
CH2NH
A
(CH2CH3)2, with respect to those of 2d: Dd-
Dd(CH2CH3)2 =0.44, Dd(CH2N)=
N
ACHTUNGTRENNUNG
0.47 ppm. We observed that upon leaving the NMR tube at
208C or heating it to 408C, another set of signals started to
appear for the diethylammoniummethyl substituents
(Figure 13). The ratio between the two signal sets did not
change anymore after 3.5 h at 408C (’2d’/’d’ 3:7, vide infra).
The chemical shifts of the new set of signals resemble that
of the bis(diphosphine) capsule d·a (Figure 13, bottom).
Metal exchange between palladium complex 2d and diphos-
phine a resulted in the formation of diphosphine d and Pd-
complex 2a, as supported by ESIMS (vide infra). The simul-
taneous presence of the tetracationic building blocks d and
2d, and the tetraanionic building blocks a and 2a in solution
1H NMR Spectroscopic Study
The two transition metals within the bisACHTNUTRGNEUNG(metallo) capsule
are situated close to one another. We were interested to
know if this will promote a metal exchange reaction or if
the two metals interact. The variable temperature H NMR
spectra of the bisACHTUNGTRENNUNG(metallo) capsules remain unchanged (at
least for 1 h at 20, 40, and 608C), which indicates that no
metal exchange occurred under these conditions. Consider-
ing the calculated distances between the two metals of the
1
bis
ACHTUNGTRENNUNG(metallo) capsules 2d·1a and 4b·1a (8.5 and 4.9 ꢃ, re-
spectively), it is unlikely that the two metals will interact
2438
www.chemasianj.org
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2011, 6, 2431 – 2443

BisACHTUNGTRENNUNG(metallo) Capsules Based on Two Ionic Diphosphines
Figure 13. 1H NMR spectra in CD3OD/CD2Cl2 (8:2 v/v). Top) capsule
2d·a (2d/a 1:2, [a]=4 mm); middle) stirring capsule 2d·a at 408C for 1–
3 h; bottom) capsule d·a. Asterisks indicate solvent signals.
resulted in the formation of four capsules: the mono-
ACHTUNGTRENNUNG(metallo) capsules 2d·a and d·2a, the bisACHTUNGTRNE(NUGN metallo) capsule
2d·2a, and the bis(diphosphine) capsule d·a (Scheme 6).
The remaining question is how can four different capsules
that are simultaneously present in solution give only two
1
signal sets in the H NMR spectrum. The free and bound
building blocks of the ionic-based capsules are in a fast ex-
change on the NMR spectroscopic timescale. Consequently,
the free- and bound building blocks give a single set of
proton resonances that represents their average.[4] The same
fast exchange process also occurs between the four capsules,
which results in this case in two sets of signals for the
+A
CH2NH CHTUNGTRENNUNG(CH2CH3)3 protons of d and 2d: one signal set for
the protons of free d, capsule d·a, and capsule d·2a, and an-
other signal set for the protons of free 2d, capsule 2d·a, and
capsule 2d·2a (Figure 13).
The exchange rate of the building blocks between various
capsules is much faster than the metal exchange rate be-
tween the ligands (which is slow on the NMR spectroscopic
1
timescale). Consequently, the H NMR spectroscopic signals
of (free and bound) d and 2d, as well as those of (free and
bound) a and 2a are not averaged and appear as separate
Figure 14. ESIMS spectra of a) capsules 2ACTHNUTRGNEU(GN d·a), b) d·a, and c) 2d·2a in
CH3OH: measured isotope patterns (see the Supporting Information).
signals (two sets of signals for the CH2NH
G
1
tons of d and 2d in the H NMR spectra.
ESIMS also support the occurrence of metal exchange be-
tween 2d and a, and consequently the formation of four
capsules. The ESIMS spectrum of capsule 2d·a in CH3OH,
after being stirred overnight at room temperature, showed
prominent ion peaks of the four capsules at m/z: 716.30 for
We were interested to know if the capsule effects the rate
and product distribution of the metal-exchange reaction.
Heating a solution containing two building blocks that
cannot form a capsule, that is, a and 2d’ (d’ is the neutral
tetraamine-xantphos ligand) also resulted in metal exchange
to give 2d’, 2a, d’, and a, as is evidenced by an NMR spec-
troscopic study. Comparison of the metal-exchange reaction
between a and 2d with that between a and 2d’ suggests that
the capsule does not effect the reaction rate and product
distribution.
[2ACHTUNGTRENNUNG
for [2d·2aÀ2Br+Na]3+ (see Figure 14, the Experimental
Section, and the Supporting Information). The ion peaks of
capsule 2d·2a clearly support the formation of 2a, and the
ion peaks of capsule d·a clearly support the formation of d.
Worth noting is that the mono
d·2a have the same elemental composition and hence give
the same m/z (these capsules are designated as 2(d·a)).
ACHTUNGTNER(NUNG metallo) capsules 2d·a and
AHCTUNGTRENNUNG
Chem. Asian J. 2011, 6, 2431 – 2443
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
2439

J. N. H. Reek et al.
FULL PAPERS
many, Version 1.0.125.0) and the calculated isotope patterns shown in the
Supporting Information are calculated by using the IsoPro 3.1 software
program. IR spectra were recorded on a Nicolet 510 FTIR spectropho-
tometer. Molecular modeling calculations were performed by using Spar-
tan ꢀ04V1.0.3 software, on the semi-empirical PM3-level.
Conclusions
We have demonstrated that the scope of ionic-based capsu-
les based on functionalized diphosphine ligands, or metal
complexes thereof, can easily be extended. The first type of
capsules is composed of one novel tetraanionic diphosphine
ligand and one complementary tetracationic calix[4]arene.
Encapsulation of a transition metal is achieved by self-as-
sembly of a transition-metal complex (Rh) containing a tet-
raanionic ligand, and a tetracationic calix[4]arene. The
second type of capsules is composed of two oppositely
charged diphosphine ligands. Simultaneous encapsulation of
two different transition metals is achieved by self-assembly
of a transition-metal complex containing a tetracationic
ligand (Pd, Pt) and a transition-metal complex containing a
tetraanionic ligand (Rh). Diphosphine ligands with different
flexibilities and shapes (i.e. different backbones) assemble
into metallocapsules with a proper capsular structure, as is
indicated by 1H NMR and 1D-NOESY spectroscopy,
ESIMS, and modeling studies. This approach for encapsula-
tion of two different metals within one cavity opens up new
opportunities for bimetallic catalysis to control the activity,
stability, and selectivity of the potential homogeneous cata-
lysts.
Synthesis: 4,5-BisACTHUNRGTNE[NUG bis(2-methoxyphenyl)phosphino]-9,9-dimethylxanthene
(x)
n-Butyllithium (2.5m in hexanes, 18.34 mL, 45.84 mmol) was added
slowly to a solution of 2-bromoanisole (5.72 mL, 45.84 mmol) in diethyl
ether (60 mL) at 08C. The solution was allowed to warm slowly to room
temperature and was stirred overnight. Next morning, the solution of 2-
lithioanisol was cooled to À458C and subsequently a solution of 4,5-bis(-
diethoxyphosphonito)-9,9-dimethylxanthene (4.13 g, 9.17 mmol) in THF
(60 mL) was added slowly. The resulting green reaction mixture was al-
lowed to warm to room temperature and was stirred overnight. Next
morning, the clear-red reaction mixture was hydrolyzed with degassed
water (5 mL) and the solvents were removed in vacuo. Subsequently, the
orange viscous oil was dissolved in dichloromethane and washed with de-
gassed brine. The organic layer was separated and the aqueous layer was
extracted with dichloromethane. The combined organic layers were dried
with MgSO4 and the solvent was removed in vacuo. The crude product
was purified by column chromatography (silica gel: EtOAc/PE 40–60).
The product x was obtained as a white powder (1.42 g, 2.03 mmol, 22%).
1H NMR (300 MHz, CDCl3, 293 K): d=7.35 (d, J=7.7 Hz, 2H; PC6H3),
7.11 (t, J=7.7 Hz, 4H; PC6H4), 6.87 (t, J=7.5 Hz, 2H; PC6H3), 6.69 (brd,
J=7.7 Hz, 4H; PC6H4), 6.61 (t, J=7.3 Hz, 4H; PC6H4), 6.51 (m, 6H;
PC6H3+PC6H4), 3.61 (s, 12H; OCH3), 1.63 ppm (s, 6H;
CACHTUNGTRENNUNG(CH3)2);
31P{1H} NMR (121.5 MHz, CDCl3, 293 K): d=À34.2 ppm (s);
13C{1H} NMR (75 MHz, CDCl3, 293 K): d=161.3 (t, J=8.0 Hz; Cq, CAr),
153.3 (brs; Cq, CAr), 133.4 (s; CH, CAr), 132.2 (s; CH, CAr), 129.7 (s; Cq,
CAr), 129.3 (s; CH, CAr), 125.9 (brs; Cq, CAr), 125.6 (s; CH, CAr), 123.0 (s;
CH, CAr), 120.5 (s; CH, CAr), 110.1 (s; CH, CAr), 55.6 (s; OCH3), 34.5 (s;
Experimental Section
C
G
CACHTNGUTRENNU(G CH3)2); HRMS (FAB+): m/z: calcd for
General Remarks
All reactions were carried out under a dry, inert atmosphere of purified
nitrogen or argon by using standard Schlenk techniques, unless stated
otherwise. Solvents were dried and distilled under nitrogen prior to use.
Diethyl ether and THF were distilled from sodium/benzophenone. Di-
chloromethane and methanol were distilled from CaH2. Deuterated sol-
vents were distilled from the appropriate drying agents. Unless stated
otherwise, all chemicals were obtained from commercial suppliers and
4,5-BisACHTNUTRGNE[NUG bis(2-methoxy-5-sulfonatophenyl)phosphino]-9,9-
dimethylxanthene tetrasodium salt (a)
Concentrated sulfuric acid (96%, 2.05 mL, 38.4 mmol) was added drop-
wise to a solution of x (0.56 g, 0.80 mmol) in dichloromethane (1 mL)
cooled to À108C. After the diphosphine was completely dissolved in the
concentrated sulfuric acid, dichloromethane was removed in vacuo. The
brown reaction mixture was slowly warmed to room temperature and
was stirred for 6 days. A second portion of concentrated sulfuric acid
(2.05 mL, 38.4 mmol) was added at À108C and the reaction mixture was
stirred for 4 more days at room temperature. Next, the reaction mixture
was hydrolyzed by slow addition of degassed ice water (16 mL) at À108C
to give the tetrasulfonic acid diphosphine a’, upon which the reaction
mixture decolorized. Subsequently, the reaction mixture was carefully
neutralized with aqueous NaOH (27%, w/w) at 08C until a pH of 8–10
was reached. The solution was thoroughly evaporated to dryness at 758C
resulting in a white powder. Methanol (100 mL) was added to the crude
product and the suspension was refluxed for 2 h. After the suspension
was cooled to room temperature the white salts (Na2SO4) were allowed
to precipitate and were filtered off. After a second extraction with meth-
anol, the product a was obtained as a white powder (0.65 gr, 0.59 mmol,
74%).
used
(pentoxy)calix[4]arene,[9] 4,5-bis(diethoxyphosphonito)-9,9-dimethylxan-
thene,[4b,17] 1,2-bis
(bis{para-[(diethylammoniumchloride)-methyl]phenyl}-
phosphino)ethane (b),[4b] 2,2’-bis
(bis{para-[(diethylammoniumchloride)-
methyl]phenyl}phosphino)-4,4’-dimethyldiphenylether (c),[4b] 4,5-bis
(bis-
{para-[(diethylammoniumchloride)methyl]phenyl}phosphino)-9,9-dime-
thylxanthene (d),[4b] trans-[Pd(Br) (p-C6H4CN)] (2d),[4a] cis-
(d-4HCl)
[PtCl2A 2A
(d-4HOTs)] (3d),[14] and cis-[PdCl (b-4HOTs)] (4b)[4b] were syn-
as
received.
5,11,17,23-TetrakisACTHNGUTERNNU(G amino)-25,26,27,28-tetrakis-
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
A
ACHTUNGTRENNUNG
C
CHTUNGTRENNUNG
thesized according to reported procedures. NMR spectra were recorded
on Varian Inova 500, Bruker Avance DRX 300, and Varian Mercury 300
NMR spectrometers. Chemical shifts are given relative to TMS (1H and
13C NMR spectra) and 85% H3PO4 (31P NMR spectra). Chemical shifts
are given in ppm. 1D-NOESY measurements (1D transient NOE) were
carried out with a DPFGSE excitation (double-pulsed field gradient spin-
echo). The default length of mixing time in the 1D-NOESY NMR pro-
gram was 400 ms and this value was used in our measurements. HRMS
FAB measurements were carried out on a JEOL JMS SX/SX 102A at
the Department of Mass Spectrometry at the University of Amsterdam.
ESIMS measurements were carried out on a Q-TOF (Micromass, Waters,
Whyttenshawe, UK) mass spectrometer equipped with a Z-spray orthog-
onal nanoelectrospray source, by using Econo Tips (New Objective,
Woburn, MA) to create an off-line nanospray, at the Department of
Mass Spectrometry of Biomacromolecules at the University of Amster-
dam. The MS spectra were processed with software tools embedded in
Masslynx software (Micromass, Waters, Whyttenshawe, UK), additional
isotopic pattern analysis was performed with the use of the Bruker Dal-
tonics Isotope Pattern software program (Bruker Daltonik, Bremen, Ger-
Tetrasodium Salt a
1H NMR (300 MHz, CD3OD, 293 K): d=7.76 (dd, J=8.6, J=2.2 Hz, 4H;
PC6H3-SO3Na), 7.42 (d, J=7.7 Hz, 2H; PC6H3), 7.23 (s, 4H; PC6H3-
SO3Na), 6.92 (d, J=8.6 Hz, 4H; PC6H3-SO3Na), 6.86 (t, J=7.6 Hz, 2H;
PC6H3), 6.54 (t, J=7.4 Hz, 2H; PC6H3), 3.67 (s, 12H; OCH3), 1.67 ppm
(s, 6H;
CACTHNGUTERNNUG
(CH3)2); 31P{1H} NMR (121.5 MHz, CD3OD, 293 K): d=
À34.8 ppm (s); 13C{1H} NMR (75 MHz, D2O, 293 K): d=163.1 (t, J=
7.7 Hz; Cq, CAr), 152.5 (brt; Cq, CAr), 135.3 (s; Cq, CAr), 131.4 (s; CH,
CAr), 131.0 (s; Cq, CAr), 130.4 (s; CH, CAr), 128.3 (s; CH, CAr), 127.4 (s;
CH, CAr), 124.2 (s; CH, CAr), 124.1 (s; Cq, CAr), 124.0 (s; Cq, CAr), 110.9
2440
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ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 2011, 6, 2431 – 2443

BisACHTUNGTRENNUNG(metallo) Capsules Based on Two Ionic Diphosphines
(s; CH, CAr), 56.0 (s; OCH3), 34.3 (s; C
(CH3)2), 30.2 ppm (s; C
E
Table 1. Observed upfield shifts (DdH) of the CH2NH
tons of b, c, d, 2d, 3d, and 4b upon capsule formation.[a]
+A
CHTUNGTRENNUNG
HRMS (FAB+): m/z: calcd for [C43H36Na4O17P2S4+H]+: 1106.9980;
found: 1107.0020.
b·a[b,c]
0.22
0.23
0.21
0.18
0.11
0.08
0.25
0.31
0.35
0.34
0.30
0.26
0.21
0.44
0.34
0.39
0.36
0.32
0.33
0.29
0.47
Nonisolated Tetrasulfonic Acid a’ (4,5-BisACHTNUGTRNEUNG[bis(2-methoxy-5-sulfonicacid-
phenyl)phosphino]-9,9-dimethylxanthene)
c·a[b,c]
d·a[b,c]
1H NMR (300 MHz, CD3OD, 293 K): d=8.05 (dd, J=8.7, J=2.2 Hz, 4H;
PC6H3-SO3Na), 7.84 (d, J=6.9 Hz, 2H; PC6H3), 7.43 (m, 4H; PC6H3-
SO3Na), 7.25 (m, 6H; PC6H3-SO3Na+PC6H3), 6.88 (m, 2H; PC6H3), 3.77
2d·1a[d]
3d·1a[d]
4b·1a[d]
2d·a[d]
(s, 12H; OCH3), 1.77 ppm (s, 6H; CACHTUNGTRNEUNG
(CH3)2); 31P{1H} NMR (121.5 MHz,
CD3OD, 293 K): d=À25.6 ppm (brs); ESIMS (CH3OH): m/z: calcd
[a] [a]=4 mm. PP/a 1:2. PP=b, c, d, 2d, 3d, and 4b. The NH+ proton
resonance was not visible because of H–D exchange with CD3OD.
[b] The assignment of the 1H NMR spectra of the capsules is fully sup-
ported by COSY NMR spectroscopy. [c] In CD3OD at 208C. [d] In
CD3OD/CD2Cl2 (8:2 v/v) at 208C.
C43H41O17P2S4+H: 1019.16; found: 1019.15.
trans-[Rh(a)Cl(CO)] (1a)
A solution of a (84.6 mg, 76.4 mmol) in methanol (7 mL) was added to a
clear yellow solution of [RhACHTNUTGRNEUNG(m-Cl)(CO)2]2 (14.9 mg, 38.9 mmol) in metha-
nol (1 mL). The reaction mixture was stirred for 30 min at room tempera-
ture and subsequently refluxed at 708C for 4 h. After cooling the brown
reaction mixture to room temperature, the solvent was evaporated in
vacuo. After washing with diethyl ether and drying in vacuo the product
1a was obtained as a brown powder. 1H NMR (300 MHz, CD3OD,
293 K): d=8.01 (dd, J=8.7 Hz, J=2.1 Hz, 4H; PC6H3-SO3Na), 7.96 (m,
2H; PC6H3), 7.68 (dt, J=6.2, J=2.1 Hz, 4H; PC6H3-SO3Na), 7.45 (m,
4H; PC6H3), 7.16 (dt, J=8.7, J=2.6 Hz, 4H; PC6H3-SO3Na), 3.65 (s,
measured isotope patterns of the capsules with the calculated ones con-
firm their elemental composition and charge state. The capsules ion
peaks correspond to 1:1 complexes and no ion peaks for higher aggre-
gates were detected. From the survey MS spectra individual candidate
ions were selected for collision-induced dissociation (CID) MSMS with
Argon as collision gas. The assignment of the capsuleꢂs ion peaks is con-
firmed by CID experiments: upon collision-induced dissociation of the
capsuleꢂs ion peaks, product peaks appeared that correspond to the cap-
suleꢂs building blocks. The reported m/z correspond to the 100% ion
peak (isotope with the highest intensity).
12H; OCH3), 1.81 ppm (s, 6H; C
ACHTUNGTRENNUNG
CD3OD, 293 K): d=22.7 ppm (d,
J
(75 MHz, CD3OD, 293 K): d=161.7 (t, J=3.6 Hz), 154.1 (t, J=9.3 Hz),
138.4 (t, J=4.4 Hz), 134.6 (s), 132.4 (s), 131.7 (s), 131.3 (s), 130.5 (s),
127.5 (s), 119.0 (s), 118.7 (s), 116.1 (s), 111.2 (s), 55.5 (s; OCH3), 34.1 (s;
Self-assembly of following capsules was done in CH3OH upon which the
capsules remained soluble, hence sodium cations were present in solu-
tion.
CACHTUNGTRENNUNG(CH3)2), 32.5 ppm (s, CCAHTUNGTREN(NUNG CH3)2); HRMS (FAB+): m/z: calcd for
[C44H36ClNa4O18P2RhS4ÀCl]+: 1236.8906; found: 1236.8972; IR (CH3OH,
293 K): n˜ =2013 cmÀ1 (CO).
Capsule z·a (C91H108N4O21P2S4)
ESIMS (CH3OH): m/z: calcd: 900.80 [z·a+2H+O]2+; found: 900.85;
calcd: 892.80 [z·a+2H]2+; found: 892.86.
5,11,17,23-Tetrakis(ammoniumchloride)-25,26,27,28-
tetrakis
ACHTUNGTRENNUNG(pentoxy)calix[4]arene (z)
A 2m solution of HCl in diethyl ether (1.50 mL, 3.00 mmol) was added
Capsule b·a (C89H108N4O17P4S4)
dropwise to a solution of 5,11,17,23-tetrakis(amino)-25,26,27,28-tetrakis-
ACHTUNGTRENNUNG(pentoxy)calix[4]arene (0.230 g, 300 mmol) in diethyl ether (25 mL), upon
ACHTUNGTRENNUNG
ESIMS (CH3OH): m/z: calcd: 901.77 [b·a+2Na]2+; found: 901.83; calcd:
890.78 [b·a+H+Na]2+; found: 890.81; calcd: 879.79 [b·a+2H]2+; found:
which a fine pink precipitate appeared. After stirring for 30 min, the vol-
atiles were removed in vacuo and z was obtained as a red powder in
quantitative yield. 1H NMR (300 MHz, CD3OD, 293 K): d=6.78 (s, 8H;
HAr), 5.50 (d, J=13.4 Hz, 4H; CHH’), 3.94 (t, J=7.3 Hz, 8H; OCH2),
3.36 (d, J=14.2 Hz, 4 h; CHH’), 1.92 (m, 8H; OCH2CH2), 1.42 (m, 16H;
C2H4CH3), 0.95 ppm (t, J=6.6 Hz, 12H; CH3); 13C{1H} NMR (75 MHz,
CD3OD, 293 K): d=156.2 (s), 136.2 (s), 124.6 (s), 123.0 (s), 75.6 (s;
C5H11), 30.2 (s; ArCH2Ar), 29.8 (s; C5H11), 28.2 (s; C5H11), 22.5 (s;
C5H11), 13.2 ppm (s, C5H11); HRMS (FAB+): m/z: calcd for
[C48H72O4N4Cl4À3HÀ4Cl]+ 765.5319; found: 765.5311.
879.80; calcd: 608.84 [b·a+3Na]3+
; found: 608.89; calcd: 601.51
[b·a+H+2Na]3+; found: 601.56; calcd: 594.19 [b·a+2H+Na]3+; found:
594.22; calcd: 586.86 [b·a+3H]3+; found: 586.89.
Capsule c·a (C101H116N4O18P4S4)
ESIMS (CH3OH): m/z: calcd: 985.80 [c·a+2Na]2+; found: 985.88; calcd:
974.81 [c·a+Na+H]2+; found: 974.91; calcd: 963.81 [c·a+2H]2+; found:
963.89; calcd: 664.86 [c·a+3Na]3+
; found: 664.92; calcd: 657.53
[c·a+H+2Na]3+; found: 657.59; calcd: 650.21 [c·a+2H+Na]3+; found:
650.27; calcd: 642.88 [c·a+3H]3+; found: 642.93.
General Procedure for Capsule Self-Assembly
Capsule d·a (C102H116N4O18P4S4)
Capsule self-assembly was done in situ. Equimolar methanol, methanol/
dichloromethane (80–90% (v) methanol), DMSO, or water solutions of
the tetracationic building block and the tetraanionic building block were
mixed at room temperature and stirred for 5–20 min., resulting in the for-
mation of the corresponding capsules.
ESIMS (CH3OH): m/z: calcd: 991.80 [d·a+2Na]2+; found: 991.84; calcd:
980.81 [d·a+Na+H]2+; found: 980.80; calcd: 969.81 [d·a+2H]2+; found:
969.82; calcd: 668.83 [d·a+3Na]3+
; found: 668.86; calcd: 661.53
[d·a+2Na+H]3+; found: 661.54; calcd: 653.87 [d·a+Na+2H]3+; found
653.89; calcd: 646.88 [d·a+3H]3+; found: 646.89.
1H NMR Spectroscopic Characterization of the Capsules
Self-assembly of the following capsules was done in H2O, upon which the
capsules precipitated. Subsequently, the capsules were isolated from the
water layer and redissolved in CH3OH, hence no sodium cations were
present in solution.
Upfield shifts (DdH) upon capsule formation are given for the protons of
the bound building blocks, with respect to those of the corresponding
free building blocks (Table 1).
Capsule z·a: Dd
ACHTUNGTRENNUNG
Capsule z·1a (C92H108N4O22P2RhS4Cl)
Capsule z·1a: Dd
4 mm).
ACHTUNGTRENNUNG
ESIMS (CH3OH): m/z: calcd: 957.75 [z·1aÀCl+H]2+; found: 957.80;
calcd: 638.84 [z·1aÀCl+2H]3+; found: 638.88.
ESIMS Measurements
Samples of the capsules with initial concentrations of 100–250 mm were
diluted in MeOH to a final concentration of 1%. Comparison of the
Chem. Asian J. 2011, 6, 2431 – 2443
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J. N. H. Reek et al.
FULL PAPERS
Capsule 2d·1a (C110H120N5O19P4PdRhS4ClBr)
Leeuwen, J. N. H. Reek, Chem. Asian J. 2011, DOI:10.1002/
asia.201100092.
ESIMS (CH3OH): m/z: calcd: 1138.73 [2d·1aÀBrÀCl]2+; found: 1138.78;
[5] a) E. G. Kuntz, CHEMTECH 1987, 17, 570–575; b) M. Schreuder
Goedheijt, P. C. J. Kamer, P. W. N. M. Van Leeuwen, J. Mol. Catal. A
1998, 134, 243–249; c) M. Schreuder Goedheijt, B. E. Hanson,
J. N. H. Reek, P. C. J. Kamer, P. W. N. M. Van Leeuwen, J. Am.
Chem. Soc. 2000, 122, 1650–1657; d) L. Leclercq, F. Hapiot, S.
Tilloy, K. Ramkisoensing, J. N. H. Reek, P. W. N. M. Van Leeuwen,
E. Monflier, Organometallics 2005, 24, 2070–2075; e) K. Ramki-
soensing, PhD thesis, University of Amsterdam, The Netherlands,
2005.
[6] a) R. L. Wife, A. B. Van Oort, J. A. Van Doorn, P. W. N. M. Van
Leeuwen, Synthesis 1983, 71–73; b) A. G. Sergeev, G. A. Artamkina,
I. P. Beletskaya, Russ. J. Org. Chem. 2003, 39, 1741–1752.
[7] a) W. P. Mul, K. Ramkisoensing, P. C. J. Kamer, J. N. H. Reek, A. J.
Van der Linden, A. Marson, P. W. N. M. Van Leeuwen, Adv. Synth.
Catal. 2002, 344, 293–298; b) W. P. Mul, H. Dirkzwager, A. A. Broe-
khuis, H. J. Heeres, A. J. Van der Linden, A. Guy Orpen, Inorg.
Chim. Acta 2002, 327, 147–159.
[8] a) C. Mꢄller, Z. Freixa, M. Lutz, A. L. Spek, D. Vogt, P. W. N. M.
Van Leeuwen, Organometallics 2008, 27, 834–838; b) H. Gulyꢅs, J.
BenetBuchholz, E. C. Escudero-Adan, Z. Freixa, P. W. N. M. Van
Leeuwen, Chem. Eur. J. 2007, 13, 3424–3430; c) Z. Freixa, P. C. J.
Kamer, M. Lutz, A. L. Spek, P. W. N. M. Van Leeuwen, Angew.
Chem. 2005, 117, 4459–4462; Angew. Chem. Int. Ed. 2005, 44, 4385–
4388; d) J. I. Van der Vlugt, R. Sablong, P. C. M. M. Magusin, A. M.
Mills, A. L. Spek, D. Vogt, Organometallics 2004, 23, 3177–3183;
e) A. J. Sandee, J. N. H. Reek, P. C. J. Kamer, P. W. N. M. Van Leeu-
wen, J. Am. Chem. Soc. 2001, 123, 8468–8476; f) L. Poorters, D.
Armspach, D. Matt, L. Toupet, S. Choua, P. Turek, Chem. Eur. J.
2007, 13, 9448–9461.
calcd: 1124.73 [2d·1aÀBrÀClÀCO]2+
[2d·1aÀBrÀCl+H]3+; found: 759.52.
; found: 1124.84; calcd: 759.49
Capsule 3d·1a (C103H116N4O19P4PtRhS4L3)
ESIMS (CH3OH): m/z: calcd: 1149.22 [3d·1aÀ2Cl]2+; found: 1149.30;
calcd: 1167.71 [3d·1aÀCl+H]2+; found: 1167.80; [3d·1aÀ3ClÀCO]3+
;
calcd: 745.16 [3d·1aÀ3Cl]3+
;
found: 745.19, calcd: 754.49
[3d·1aÀ2Cl+H]3+; found: 754.53; calcd: 766.48; found: 766.53.
Capsule 4b·1a (C90H108ClN4O18P4PdRhS4L2)
ESIMS (CH3OH): m/z: calcd: 1015.16 [4b·1aÀ2Cl]2+; found: 1015.27;
calcd: 1033.15 [4b·1aÀCl+H]2+
;
found: 1033.23; calcd: 677.11
[4b·1aÀ2Cl+H]3+; found: 677.19; calcd: 664.45 [4b·1aÀ3Cl]3+: found:
664.52; calcd: 655.12 [4b·1aÀ3ClÀCO]3+; found: 655.19.
Stirring a CH3OH solution of capsule 2d·a overnight at room tempera-
ture resulted in a mixture of four capsules (2d·a, d·2a, 2d·2a, and d·a) as
is indicated by ESIMS (CH3OH). Capsules 2d·a and d·2a have the same
elemental composition and hence can give the same m/z, we have desig-
nated these capsules as 2
Capsules 2(d·a) (C109H120N5O18P4PdS4Br)
calcd: 1084.77 [2 found: 1084.98; calcd: 1073.78 [2-
(d·a)ÀBr+Na]2+
ACHTUNGTRNE(NUNG d·a).
ACHTUNGTRENNUNG
A
;
A
;
G
;
AHCTUNGTRENNUNG
ACHTUNGTRENNUNG
Capsule 2d·2a (C116H124N6O18P4Pd2S4Br2)
calcd: 1177.45 [2d·2aÀ2Br]2+
;
found: 1177.25; calcd: 827.13
[9] R. A. Jakobi, V. Bçhmer, C. Gruettner, D. Kraft, W. Vogt, New J.
Chem. 1996, 20, 493–501.
[2d·2aÀBr+2Na]3+
;
found: 826.95; calcd: 812.48 [2d·2aÀBr+2H]3+
;
found: 812.32; calcd: 792.49 [2d·2aÀ2Br+Na]3+; found: 792.60; calcd:
[10] a) C. A. Schalley, R. K. Castellano, M. S. Brody, D. M. Rudkevich,
G. Siuzdak, J., Jr. Rebek, J. Am. Chem. Soc. 1999, 121, 4568–4579;
b) R. Zadmard, A. Kraft, T. Schrader, U. Linne, Chem. Eur. J. 2004,
10, 4233–4239; c) D. P. Weimann, C. A. Schalley, Supramol. Chem.
2008, 20, 117–128.
[11] F. Corbellini, R. Fiammengo, P. Timmerman, M. Crego-Calama, K.
Versluis, A. J. R. Heck, I. Luyten, D. N. Reinhoudt, J. Am. Chem.
Soc. 2002, 124, 6569–6575.
785.17 [2d·2aÀ2Br+H]3+; found: 785.28.
Capsule d·a (C102H116N4O18P4S4)
calcd: 991.80 [d·a+2Na]2+; found: 991.93; calcd: 980.81 [d·a+Na+H]2+
;
found: 980.96; calcd: 969.82 [d·a+2H]2+; found: 969.98; calcd: 654.21
[d·a+Na+2H]3+; found: 654.33; calcd: 646.88 [d·a+3H]3+; found: 646.99.
[12] a) High-Resolution NMR Techniques in Organic Chemistry (Ed.: T.
Claridge), Elsevier, Amsterdam, 2000; b) D. Neuhaus, M. P. Wil-
liamson, The Nuclear Overhauser Effect in Structural and Conforma-
tional Analysis, Second Edition, Wiley-VCH, New York, 2000; c) A.
Shivanyuk, J. Rebek, Jr., J. Am. Chem. Soc. 2003, 125, 3432–3433;
d) A. Shivanyuk, M. Saadioui, F. Broda, I. Thondorf, M. O. Vysot-
sky, K. Rissanen, E. Kolehmainen, V. Bçhmer, Chem. Eur. J. 2004,
10, 2138–2148.
[13] a) R. Zadmard, M. Junkers, T. Schrader, T. Grawe, A. Kraft, J. Org.
Chem. 2003, 68, 6511–6521; b) R. Zadmard, T. Schrader, T. Grawe,
A. Kraft, Org. Lett. 2002, 4, 1687–1690; c) T. Grawe, T. Schrader,
M. Gurrath, A. Kraft, F. Osterod, Org. Lett. 2000, 2, 29–32; d) T.
Grawe, T. Schrader, R. Zadmard, A. Kraft, J. Org. Chem. 2002, 67,
3755–3763; e) B. M. OꢂLeary, T. Szabo, N. Svenstrup, C. A. Schalley,
A. Lꢄtzen, M. Schaefer, J. Rebek, Jr., J. Am. Chem. Soc. 2001, 123,
11519–11533.
[14] T. S. Koblenz, PhD thesis, University of Amsterdam, The Nether-
lands, 2010.
[15] M. A. Zuideveld, B. H. G. Swennenhuis, M. D. K. Boele, Y. Guari,
G. P. F. Van Strijdonck, J. N. H. Reek, P. C. J. Kamer, K. Goubitz, J.
Fraanje, M. Lutz, A. L. Spek, P. W. N. M. Van Leeuwen, J. Chem.
Soc. Dalton Trans. 2002, 2308–2317.
[16] a) G. Petocz, Z. Berente, T. Kegl, L. Kollar, J. Organomet. Chem.
2004, 689, 1188–1193; b) L. A. Van der Veen, P. K. Keeven, P. C. J.
Kamer, P. W. N. M. Van Leeuwen, Dalton Trans. 2000, 13, 2105–
2112; c) R. Van Duren, J. I. Van der Vlugt, H. Kooijman, A. L. Spek,
D. Vogt, Dalton Trans. 2007, 10, 1053–1059; d) C. Bianchini, A.
Meli, W. Oberhauser, A. M. Segarra, C. Claver, E. J. G. Suarez, J.
[1] a) J. M. Lehn, Supramolecular Chemistry: Concepts and Perspectives.
1995, Wiley-VCH, Weinheim; b) L. R. MacGillivray, J. L. Atwood,
Angew. Chem. 1999, 111, 1080–1096; Angew. Chem. Int. Ed. 1999,
38, 1018–1033.
[2] a) T. S. Koblenz, J. Wassenaar, J. N. H. Reek, Chem. Soc. Rev. 2008,
37, 247–262; b) Chemistry in Self-Assembled Nanoreactors, J. I.
Van Der Vlugt, T. S. Koblenz, J. Wassenaar, J. N. H. Reek in Molec-
ular Encapsulation: Organic Reactions in Constrained Systems (Eds.:
U. H. Brinker and J.-L. Mieusset), Wiley, Chichester, UK, 2010,
p. 145–174; c) D. M. Vriezema, M. C. Aragones, J. A. A. W. Ele-
mans, J. J. L. M. Cornelissen, A. E. Rowan, R. J. M. Nolte, Chem.
Rev. 2005, 105, 1445–1489; d) Supramolecular Catalysis (Ed.:
P. W. N. M. Van Leeuwen), Wiley-VCH, Weinheim, 2008.
[3] a) D. H. Leung, R. G. Bergman, K. N. Raymond, J. Am. Chem. Soc.
2006, 128, 9781–9797; b) D. H. Leung, R. G. Bergman, K. N. Ray-
mond, J. Am. Chem. Soc. 2007, 129, 2746–2747; c) M. L. Merlau, M.
Del Pilar Mejia, S. T. Nguyen, J. T. Hupp, Angew. Chem. 2001, 113,
4369–4372; Angew. Chem. Int. Ed. 2001, 40, 4239–4242; d) M. Kuil,
T. Soltner, P. W. N. M. Van Leeuwen, J. N. H. Reek, J. Am. Chem.
Soc. 2006, 128, 11344–11345; e) A. W. Kleij, M. Lutz, A. L. Spek,
P. W. N. M. Van Leeuwen, J. N. H. Reek, Chem. Commun. 2005,
3661–3663; f) V. F. Slagt, P. C. J. Kamer, P. W. N. M. Van Leeuwen,
J. N. H. Reek, J. Am. Chem. Soc. 2004, 126, 1526–1536.
[4] a) T. S. Koblenz, H. L. Dekker, C. G. De Koster, P. W. N. M. Van
Leeuwen, J. N. H. Reek, Chem. Commun. 2006, 16, 1700–1702;
b) T. S. Koblenz, H. L. Dekker, C. G. De Koster, P. W. N. M. Van
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Chem. Asian J. 2011, 6, 2431 – 2443

BisACHTUNGTRENNUNG(metallo) Capsules Based on Two Ionic Diphosphines
Mol. Catal. A 2007, 265, 292–305; e) W. L. Steffen, G. J. Palenik,
Inorg. Chem. 1976, 15, 2432–2439.
[17] a) P. Dierkes, S. Ramdeehul, L. Barloy, A. De Cian, J. Fischer,
P. C. J. Kamer, P. W. N. M. Van Leeuwen, J. A. Osborn, Angew.
Chem. 1998, 110, 3299–3301; Angew. Chem. Int. Ed. 1998, 37, 3116–
3118; b) H. Ito, A. Watanabe, M. Sawamura, Org. Lett. 2005, 7,
1869–1871; c) M. Schreuder Goedheijt, B. E. Hanson, J. N. H. Reek,
P. C. J. Kamer, P. W. N. M. Van Leeuwen, J. Am. Chem. Soc. 2000,
122, 1650–1657.
Received: January 28, 2011
Published online: July 4, 2011
Chem. Asian J. 2011, 6, 2431 – 2443
ꢁ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
2443