Synthesis and self-assembly of a rigid exotopic bisphenanthroline macrocycle: Surface patterning and a supramolecular nanobasket

Article abstract of DOI:10.1002/chem.200305770

The synthesis and characterisation of a rigid nanoscale macrocycle with two exotopic phenanthroline binding sites is reported. Scanning tunnelling microscopy (STM) at the solid-liquid interface reveals the formation of highly ordered monolayers of macrocy

Full text of DOI:10.1002/chem.200305770

FULL PAPER
Synthesis and Self-Assembly of a Rigid Exotopic Bisphenanthroline
Macrocycle: Surface Patterning and a Supramolecular Nanobasket
[a]
Venkateshwarlu Kalsani, Horst Ammon,[b] Frank Jäckel,[c] Jürgen P. Rabe,[c] and
Michael Schmittel*[a]
Abstract: The synthesis and characteri-
sation of a rigid nanoscale macrocycle
with two exotopic phenanthroline bind-
ing sites is reported. Scanning tunnel-
ling microscopy (STM) at the solid–
liquid interface reveals the formation
of highly ordered monolayers of mac-
rocycles with dimensions that are in
good agreement with the calculated
structure. Using the HETPHEN con-
cept several bisheteroleptic coordina-
tion complexes with other phenanthro-
lines and a nanoscale basket assembly
were prepared in presence of copper(i)
ions. NMR spectroscopy, mass spectro-
metric data and elemental analysis
point to three distinct isomers of the
basket assembly in solution. A silver
basket was prepared and readily con-
verted to its copper analogue. Electro-
spray ionisation (ESI)-MS and spectro-
photometric investigations provided
additional mechanistic insight into the
assembly process. Hence, the exotopic
bisphenanthroline macrocycle in com-
bination with HETPHEN concept
proves to be very effective in control-
ling the compositional aspects of multi-
component self-assembly.
Keywords: copper · macrocycles ·
N
ligands
·
scanning probe
microscopy · self-assembly
Introduction
Recently, the synthesis of rigid or shape-persistent macro-
cycles of nanometer scale has become an important avenue
of research.[6] In contrast to ring systems with flexible link-
ages, a macrocycle with a rigid back bone is an attractive
building block for supramolecular architectures to address
defined interior and exterior spatial arrangements and rela-
tionships. Over the years, rigid macrocycles with or without
coordinating ligand sites have been reported.[6] In particular,
macrocycles incorporating polypyridyl units have received
ample interest due to their coordination properties in pres-
ence of suitable metal ions.[7] Schlüter and Grave have re-
viewed the recent developments on rigid nanosized macro-
cycles and outlined their assets.[6h] Although many of the
rigid macrocycles reported to date contain bipyridine and
terpyridine units, most of them (bipyridine) still lack direc-
tionality in their coordination behaviour (Figure 1) due to
rotational movements, thus allowing for both exo and endo
coordination. For defined exo or endo coordination phenan-
throlines appear superior to bipyridines as a free rotating
bond in between chelating nitrogens is fixed. Sauvage,
Lüning and others have used flexible macrocycles incorpo-
rating endotopic phenanthrolines to engineer functional cat-
enanes, rotaxanes,[8] concave reagents[9] and molecular
knots.[10] To the best of our knowledge, the only rigid macro-
cycle with phenanthroline units has been reported by
Rehahn.[11] This macrocycle, however, exhibits endotopic co-
ordination sites, hence prohibiting any access to extended
oligomeric structures. Therefore we envisaged the synthesis
Macrocycles[1] have attracted increasing attention over the
last years due to their applicability for surface patterning
and as components of supramolecular assemblies. Monolay-
ers of macrocycles on solid supports or interfaces have been
suggested to serve as 2D templates for the construction of
larger supramolecular 3D assemblies and as matrices for the
incorporation of guest molecules.[2–4] These monolayers have
been characterised by scanning tunnelling microscopy
(STM), Langmuir–Blodgett techniques, X-ray diffraction,
photoelectron and infrared spectroscopy as well as ellipsom-
etry.[2–5]
[a] V. Kalsani, Prof. Dr. M. Schmittel
Center of Micro and Nanochemistry and Engineering
Organische Chemie I, Universität Siegen
Adolf-Reichwein-Str., 57068 Siegen (Germany)
Fax :(+49)271-740-4356
E-mail: schmittel@chemie.uni-siegen.de
[b] Dr. H. Ammon
Institut für Organische Chemie der Universität Würzburg
Am Hubland, 97074 Würzburg (Germany)
[c] Dipl-Phys. F. Jäckel, Prof. Dr. J. P. Rabe
Humboldt University Berlin, Department of Physics
Newtonstraße 15, 12489 Berlin (Germany)
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
Chem. Eur. J. 2004, 10, 5481 – 5492
DOI: 10.1002/chem.200305770
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5481

FULL PAPER
Figure 1. Schematic representation of binding motifs in macrocycles con-
taining bipyridines and phenanthrolines as the coordinating ligands.
of a rigid macrocycle with phenanthrolines that has exotopic
coordination sites.
Herein, we present the experimental details of the synthe-
sis[12] of the rigid, nanosized (ca. 2.70 nm length) macrocycle
1 with opposite exotopic phenanthroline sites, its self-assem-
bly studied with scanning tunneling microscopy (STM) at a
solid liquid interface and its potential as a useful building
block for engineering a heteroleptic supramolecular basket
structure through self-assembly in solution along the strat-
egy outlined in Scheme 1.
Scheme 1. Schematic representation of the strategy for the self-assembly
of a three-component supramolecular basket.
Results and Discussion
Synthesis: Macrocycle 1 was prepared by combining three
building blocks by a series of Sonogashira couplings as de-
picted in Scheme 2 and as communicated earlier.[12] The key
building block 3, equipped with solubilizing hexyl chains in
the 3,8-positions,[13] served as source of the exotopic phenan-
throline site. Following the synthetic protocol, phenanthro-
line 3 was first connected with the bisalkyne spacer 4. After
deprotection of 5a, product 5b was subsequently linked to
two 1,3-diiodobenzene units 6. Finally, the resultant com-
pound 7 was coupled with 5b to afford the macrocycle 1.
Macrocycle 1 precipitated as pale yellow microcrystals in
trichloromethane, the structure of which was unambiguously
1
assigned by elemental analysis, H NMR spectroscopy, and
ESI MS. The ring structure was convincingly visualised by
STM.
Synthesis of a handle for a supramolecular basket assembly:
The construction of well-defined basket-shaped molecules is
of interest, not only because of their potential use in host–
guest chemistry, but also to place defined functionalities
Scheme 2. Preparation of macrocycle 1.
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Supramolecular Nanobaskets
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above a nanoscale array. While some first cyclophane assem-
blies have been reported to date,[14] these are well below the
nanoscale dimensions. Owing to our earlier results with the
HETPHEN concept (allowing for the selective preparation
of heteroleptic bisphenanthroline copper/silver complexes),
we chose 2 as a counter part to the macrocycle to prepare
the nanoscale basket assembly. The HETPHEN approach[15]
utilises steric and electronic effects originating from bulky
aryl substituents at one of the two phenanthroline ligands
(as seen in 2 and in 10 and 11) to steer the coordination
equilibrium both kinetically and thermodynamically towards
the heteroleptic bisphenanthroline complex. Ligands 2, 10
and 11 are designed to carry steric stoppers at the 2- and 9-
positions of the phenanthroline. Ligand 2 was obtained in
four steps starting from the parent 1,10-phenanthroline (8).
The arene groups were added in 2- and 9-position according
to Sauvage[16] in a stepwise fashion as depicted in Scheme 3.
and hydrochloric acid, we obtained the free phenol 12,
which was subsequently treated with 13 to yield 2 in 73%.
Ligand 2 has a H NMR spectrum with a singlet at d=
6.85 ppm for the four protons of the 1,4-phenylene unit and
a ESI MS spectrum with only two signals, one being centred
at 1175.7 (25%) [2+H]+ and the other at 588.8 (100%)
[2+2H]2+. The isotopic patterns are in agreement with the
calculated ones. All other data is also in accordance with its
structure (see Experimental Section).
1
Self-assembly at the solid–liquid interface: Figure 2 displays
an STM current image of a highly ordered monolayer of the
macrocycle 1 at the solution–HOPG interface (HOPG=
highly oriented pyrolytic graphite). The arrangement is char-
acterised by an oblique unit cell containing one molecule
(a=2.98ꢀ0.15 nm, b=3.08ꢀ0.13 nm and a=47ꢀ68). The
area of the unit cell of A=6.6ꢀ0.3 nm2 is in good agree-
ment with the space require-
ments of a single molecule lying
completely flat on the substrate
(~6.3 nm2). The bright areas of
the image can be attributed to
the conjugated parts of the
macrocycle, since the energy
difference between the frontier
orbital and the Fermi level of
the graphite substrate is rather
small.[17] The dark areas of the
image between the rings can be
assigned to the aliphatic side
chains that could not be visual-
ised, probably due to their high
conformational mobility on a
timescale faster than the STM
imaging. Notably, also the area
inside the rings could be
imaged and is probably dynami-
cally occupied by solvent mole-
Scheme 3. Synthetic Scheme for the preparation of 2.
cules. Owing to the orientation
and spacing of the phenanthro-
The addition products were isolated and oxidised with acti-
vated manganese dioxide to afford the 2,9-disubstituted
1,10-phenanthroline. After deprotection of 10 with pyridine
line units being ideal for metal ion coordination, one might
envisage using these monolayers to study the formation and
the electronic properties of coordination polymers.
Figure 2. STM current image of a highly ordered monolayer of macrocycle 1. Parameters were ꢁ1.4 V sample bias and 100 pA average tunneling current.
Unit cell and macrocycle structure are indicated. a) Model for the arrangement. b) PM3 minimized dimensions of the macrocycle.
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Self-assembly in solution
In the following we probed the complexation behaviour
of the handle 2. A mixture of 2 and [Cu(MeCN)4]PF6 (1:1)
resulted in a yellow solution, the analysis of which by ESI-
MS and 1H NMR spectroscopy indicated the presence of
mainly [Cu(2)]+ along with unreacted (protonated in case of
ESI MS) phenanthroline (Supporting Information: Figure
S1a). The isotopic distribution of [Cu(2)]+ is in excellent
agreement with the calculated one. However, it is evident
from the yellow colour and the absence of any metal-to-
ligand charge transfer (MLCT) band in the region of 450–
500 nm that no macrocyclic structure with a [Phen-Cu-
Phen]+ complex has formed (Supporting Information: Fig-
ure S1b).[18] From these experiments it is clear that the two
shielded phenanthroline sites act as expected, not allowing
for ring closure by formation of a homoleptic ring architec-
ture or any other oligomeric
Complexation behaviour of the macrocycle and of the
handle: The presence of two rigid exotopic binding sites ren-
ders macrocycle 1 an attractive building block for nanoscale
assemblies, particularly in combination with tetrahedrally
coordinating metal ions (Cu+ or Ag+)[7a] and HETPHEN li-
gands 2, 10 and 11, which contain steric stopper groups in
2,9-position.[15] First, the ability of macrocycle 1 to form
complexes with 10 and 11 was probed in presence of Cu+
(Scheme 4). Rewardingly, only complexes C1 and C2, but no
oligomers of macrocycle, could be detected by both ESI-MS
and 1H NMR spectroscopy, highlighting the utility of the
HETPHEN concept in engineering heteroleptic supramolec-
ular assemblies.
structures.
To create a model complex
for comparison with the target
basket (Scheme 2), we reacted
2 with 5a in presence of [Cu-
(MeCN)4]PF6 (1:2:2) to furnish
1
C3 (Scheme 5). H NMR spec-
troscopy, ESI-MS and other
spectroscopic data are in good
agreement with the proposed
structure (see Experimental
Section).
ESI MS shows a signal cen-
tred at m/z 1560.2 Da corre-
Scheme 4. Formation of complexes C1 and C2.
sponding to the C3 complex
[Cu2(2)(5a)2]2+. Again, the ex-
perimental isotopic distribution
In the ESI-MS characteristic signals are observed corre-
sponding to C1 and C2, with the experimental isotopic dis-
tributions being in good agreement with the calculated ones
(Supporting Information: Figure S2). Because of the sym-
is in good agreement with the calculated one. Formation of
complex C3 is further confirmed by collisional fragmenta-
tion of C3 producing the fragment [Cu2(2)(5a)]2+, whose
isotopic distribution is in agreement with its proposed com-
position (Supporting Information: Figure S3).
1
metric structure and the sharp signals, the H NMR spectra
is readily rationalised. Characteristic high-field shifts were
observed for aryl protons of ligands 10 and 11 in the com-
plexes C1 or C2, respectively, a clear indication for forma-
tion of heteroleptic complexes as demonstrated earlier.[15]
Self-assembly of a nanoscale basket assembly and its metal
exchange: Following the proposal depicted in Scheme 1,
complexation of 1 and 2 with appropriate metal ions such as
Scheme 5. Assembly of C3 complex from 2 and 5a.
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Supramolecular Nanobaskets
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CuI or AgI ions should furnish a
basket-shaped heteroleptic met-
allo assembly. Upon addition of
macrocycle 1 to 2 and [Cu-
(MeCN)4]PF6 (1:1:2), the so-
lution turned deep red. The
analysis of this solution by ESI-
MS indicated the formation of
[Cu2(1)(2)]2+ (C4) as the exclu-
sive species. The isotopic split-
ting pointing to a doubly charg-
ed species is in perfect agree-
ment with its proposed compo-
1
sition (Figure 3). The H NMR
spectrum shows that a hetero-
leptic bisphenanthroline com-
plex has formed at the copper
ions, as can be seen from typi-
cal high-field shifts of the mesi-
tyl and dimethylphenoxy pro-
tons at about 5.5–6.3 ppm
(Figure 4). The sharp signals in
1
the H NMR spectrum rule out
the existence of any higher ag-
gregates or oligomers.
Spectral comparison of C4 with
C1 and C2: The absorption
Figure 4. Parts of the NMR spectra (600 MHz) of C2, C3 and C4. Complex C3 shows signals of conformational
isomers at Hc and Ha (*=impurity).
Figure 3. Positive ESI-MS spectrum of [(1)(2)(Cu)2]2+ (C4) in dichloromethane. The insert shows the calculated (bottom) and experimental isotopic split-
tings (top).
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M. Schmittel et al.
FULL PAPER
spectra of the heteroleptic complexes C1, C2 and C4
(Figure 5) show the presence of similar bands. The strong
bands at 250–400 nm correspond to ligand p–p transitions.[19]
Figure 6. Energy-minimised structure of the basket assembly C4z (top),
indicating that Hzc of 2 and Hzd of 1 are far away from each other in line
with NOESY data. The structure of C4xy is expected to look like the
isomer shown in the two bottom pictures (left=side view; right=top
view). Conformational motions of the entangled polyether chain in C4xy
to generate C4z are prevented by a high barrier due to the restricted
space in the core of the macrocycle.
Figure 5. UV-visible absorption spectra of C1, C2 and C4 (basket assem-
bly) in dichloromethane (2.6”10ꢁ6 m).
The absorption band at 491 nm is assigned to the MLCT
state that is responsible for the red colour of the complexes.
These absorptions are in good agreement with those of
other Cu+ heteroleptic bisphenanthroline assemblies.[20] The
good match of the MLCTband for all three complexes is in-
dicative of a similar environment at the metal centre. More-
over, the oscillator strength of the MLCTband at l=
491 nm (emax =23113, 21395 and 18608mꢁ1 cmꢁ1 for C1, C2
and C4, respectively) is in good agreement with the pro-
posed two Cu+ ions per complex. Analogous Cu+-contain-
Scheme 6. Cartoon representation of possible isomers of [Cu2(1)(2)]2+
(C4).
ing systems in which one Cu+ is present[21] exhibit emax
8500mꢁ1 cmꢁ1.
=
By chromatography we could separate C4z from C4x,y (1H
NMR spectra of isolated C4x,y and C4z are included in the
Supporting Information: Figure S8) and confirm the compo-
sition [(1)(2)(Cu)2]2+ for both fractions by ESI-MS.
Although ESI-MS and UV-visible data provide a clear
and convincing picture for the composition of C4 as
[(1)(2)(Cu)2]2+, the 1H NMR spectra of the complex be-
tween 5.5–7 ppm is much more complex than expected, re-
vealing three well-resolved sets of signals (in 59:24:17
ratio;[22] Figure 4). In particular, protons Ha, Hb, Hc and Hd
(see Scheme 1) appear well separated, indicating only very
slow interconversion between the different isomers. The iso-
mers will be depicted as C4x, C4y and C4z.
How can we rationalise the occurrence of various isomers
of the composition [(1)(2)(Cu)2]2+? Depending on the spa-
tial arrangement of the polyether chain in C4 there may
exist different isomers as depicted in Scheme 6. From these
choices the rotaxane-type model III can easily be discarded,
owing to a rather high barrier (as predicted by molecular
modelling[23]) needed for threading the bulky diarylphenan-
throline unit of 2 into macrocycle 1 (Supporting Informa-
tion: Figure S5). The high barrier is mainly due to repulsion
of the 2,6-dimethylphenyl groups at phenanthroline of 2 and
the methoxy groups in 1.
In contrast to signal set z, the other two sets of signals,
that is, for C4x,y, show notable NOE effects between Hc
and Hd protons; this indicates close proximity of the poly-
ether bridge and the macrocycle, as depicted in a cartoon-
type fashion in model II. In support of a model II type struc-
ture for both C4x and C4y, protons Hxa and Hya have signals
that are shifted down-field with respect to Hza, while the sig-
nals for protons Hxb and Hyb are shifted to high-field with re-
spect to Hzb. This can only be rationalised by a distorted ge-
ometry at the copper(i) ion, with the dimethylphenoxy unit
being closer to the phenanthroline of 1 than the mesityl
unit. This is due to a severe conformational pull exerted by
Structural aspects: Further information about the structure
of the isomers can be deduced from extensive ROESY in-
vestigations (Supporting Information: Figures S6 and S7).
For one set of the signals (indicated by z; assigned to C4z)
there is no NOE effect between Hzc and Hzd, indicating that
the ether bridge is well away from the macrocycle (>6 Š),
in agreement with a basket type structure (Figure 6, and
model I in Scheme 6) of C4z. In addition, all signals of C4z
show a remarkable similarity in the shifts with those of the
complexes C2 and C3 (Figure 4), for which we have to
assume an unconstrained polyether chain and a planar mac-
rocycle, respectively. Hence, C4z is best described by the
basket structure as depicted by an energy-minimised struc-
ture from force field calculations (Figure 6 top).[23]
However, C4z is only the minor constituent of three dif-
ferent complexes with the same composition [(1)(2)(Cu)2]2+
.
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Supramolecular Nanobaskets
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the polyether chain that is entrapped in the macrocycle as
shown in model II. It is, however, impossible to provide
exact conformational differences along the polyether chain
of 2 distinguishing the two isomers C4x and C4y, in particu-
lar, since also a slight folding of the macrocycle may be in-
volved.[24] The interconversion between C4x and C4y occur-
ring at temperatures higher than ꢁ208C precluded chroma-
tographic separation.
leaving only trajectory B to form the second copper com-
plex.
It is, however, surprising to learn that even at tempera-
tures as high as 608C interconversion between C4x,y and
C4z, that is, between model I and II isomers, remains com-
pletely shut down. Such a high barrier can only be rational-
ised if interconversion of C4x,y and C4z is not possible by
conformational changes along the polyether chain. Molecu-
lar modelling indeed proposed that the entanglement of the
cramped polyether chain within the void of the macrocycle
will preclude conformational relaxation (Figure 6). Alterna-
A key for further understanding is to picture the forma-
tion of the basket assembly. Upon formation of the mononu-
clear complex [(1)(2)(Cu)]+ (Scheme 7) the free 2,9-diaryl-
tively,
a
dissociation/association process connecting
[Cu2(1)(2)]2+Ð[Cu2(1)(2)]2+
could potentially bring
open
about the conformational flexibility needed for interconver-
sion (cf. to Scheme 7), but apparently the exergonic associa-
tion [Cu2(1)(2)]2+open![Cu2(1)(2)]2+ kinetically outruns the
slow escape of the conformationally locked polyether chain.
If the above rationale was correct, addition of ligand 14[27]
to C4 should lead to a competitive binding of 14 to
[Cu2(1)(2)]2+open, thereby freeing the hitherto kinetically
locked equilibration between C4x,y and C4z. Indeed, after
adding one mole equivalent of 14 to C4x,y,z we saw enrich-
ment of C4x,y at the expense of C4z, while parallel the new
complex [Cu2(1)(14)2]2+ was formed (Scheme 8). This result
suggests that dissociation/association at the copper phenan-
throline site in pure C4x,y,z takes place, but does not lead
to interconversion of the isomers due to entrapment of the
polyether chain in the void of the macrocycle. Moreover,
this experiments indicates that model II structures are ther-
modynamically more stable than the basket (model I) owing
to attractive interactions.[26]
Metal exchange: A silver basket was made by mixing 1 and
2 with AgBF4 in dichloromethane, affording a yellowish
solution. Analysis of this by ESI MS indicated a signal at
m/z=1452.2 with a charge 2+. Isotopic splitting was in
good agreement with its proposed composition [Ag2(1)(2)]2+
.
1
The H NMR spectrum of [Ag2(1)(2)]2+ again indicated the
presence of three isomers in a similar ratio as for the
[Cu2(1)(2)]2+ complex. Upon the addition of [Cu(MeCN)4]+
in dichloromethane (2 equiv, 8 additions, 30 min), the
Scheme 7. Cartoon representation of the formation of [Cu2(1)(2)]2+ (C4)
leading to two sets of isomers (models I and II).
[Ag2(1)(2)]2+ was quantitatively converted to [Cu2(1)(2)]2+
.
In the conversion process, signals of the intermediate species
[AgCu(2)(1)]+2 were detected (Supporting Information:
Figure S4). Importantly, the conversion of [Ag2(1)(2)]2+ to
[Cu2(1)(2)]2+ does not entail detectable changes in the com-
substituted phenanthroline site of 2 has actually only two
major trajectories[25] to move towards the second phenan-
throline of macrocycle 1: either
it stretches the polyether chain
to such an extent that approach
of the loose phenanthroline
along trajectory A is possible.
Alternatively, the polyether
chain may fold partly into the
macrocycle due to stabilizing
interactions[26] between the
handle and the unsaturated
macrocycle. This will severely
limit the translational freedom
of the loose binding site of 2 Scheme 8. Competitive binding of ligand 14.
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M. Schmittel et al.
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position C4x:C4y:C4z. Hence, metal exchange after dissoci-
ation followed by association is faster than conformational
relaxation from model I to model II.
ESI MS investigations, thermodynamic and UV-visible stud-
ies: Insight into the mechanistic pathways and thermody-
namic features of supramolecular structures is of great inter-
est to engineer well-defined, discrete architectures and to
understand the self-recognition phenomena. Very few re-
ports are at hand providing mechanistic insight into the het-
eroleptic organisation.[14a,28] The present study uses ESI MS
for qualitative analysis and spectrophotometry for quantita-
tive analysis. Both measurements were carried out in di-
chloromethane, which we have found is a good solvent for
such titrations.[29] At first, a series of ESI MS titration ex-
periments was carried out to obtain a qualitative picture
about the intermediates on the way to [Cu2(1)(2)]2+. In each
case, it was ascertained that the thermodynamic equilibrium
had been reached, as the spectra recorded proved to be con-
stant over time. A table of the results is presented in the
supplementary material.
Scheme 10. Proposed species (cartoons) in equilibrium when 1 and 2
were titrated with Cu+.
tions with macrocycle 1 being present along with Cu+, ho-
moleptic assemblies were observed in absence of 2. These,
however, readily disappeared upon addition of 2, indicating
the higher stability of the heteroleptic basket assembly
Scheme 11
Scheme 11. Proposed species (cartoons) in equilibrium when 1 and Cu+
were titrated with 2.
ESI-MS titration of 2 and Cu+ with 1: In a first series of ex-
periments 2 and the CuI salt were titrated with 1. The titra-
tion was carried out in five additions and excess addition of
1 did not effect [Cu2(1)(2)]2+, indicating a high stability of
this assembly under the chosen conditions. During the
course of titration four intermediates were observed apart
from the final basket-shape assembly. All the proposed in-
termediates (see the pictorial description in Scheme 9) were
in good agreement with their isotopic splittings and served
as models for the spectrophotometric titration using SPEC-
FIT[30] program.
UV-visible titration of 2 and 1 with Cu+: The ESI-MS titra-
tions suggest a qualitative picture of the intermediates in the
self-assembly process. Though, the mechanistic pathways
vary with the type of titration, they always lead to
[Cu2(1)(2)]2+ as the final complex. Because of the simplicity
observed with the second series of titration experiments
with ESI-MS, the same type of titration was carried out for
spectrophotometric studies. Hence, these titrations were per-
formed by titrating 2 (3.3 10ꢁ6 m) and 1 (3.3 10ꢁ6 m), with ali-
quot amounts of a solution of CuI in dichloromethane for
20 additions (total 4 equiv of Cu+). Figure 7 displays
changes in UV-visible spectrum upon CuI salt addition, with
the solution turning red due to the MLCTtransitions at
~490 nm. The inset shows the plots of absorbance changes at
490 nm for 2 and 1 versus CuI salt, indicating that the com-
plexation process is finished when two equivalents of CuI
salt are added and excess addition of Cu+ does not effect
Scheme 9. Proposed species (cartoons) in equilibrium when 2 and Cu+
were titrated with 1.
ESI-MS titration of 2 and 1 with Cu+: The second series of
experiments was carried out by the titration of 2 and 1 with
the CuI salt. The CuI salt (two equivalents) was added in
five portions. Again, excess of addition did not change the
spectrum. Though it was possible to detect three intermedi-
ates in minute amounts, the final basket assembly appeared
as the major component throughout the titration, indicating
a strong tendency to form [Cu2(1)(2)]2+. The obtained re-
sults are presented in Scheme 10.
ESI-MS titration of 1 and Cu+ with 2: Finally in a third set
of titrations, 1 and the CuI salt were titrated with a solution
of 2; the obtained results are depicted in Scheme 10 along
with their proposed structures. Due to the starting condi-
Figure 7. Spectrophotometric titration of 2 and 1 by aliquot amounts of
CuI salt in 20 additions. Solvent: dichloromethane. T=25(1)8; [2] and
[1]=3.30”10ꢁ6 m. Stability constants are given down to UV-visible spec-
tra.
5488
ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Chem. Eur. J. 2004, 10, 5481 – 5492

Supramolecular Nanobaskets
5481 – 5492
changing the tunneling parameters to small tunneling impedance. This
allows in-situ x,y calibration of the piezo-scanner and drift-correction of
the images recorded.
the already formed basket assembly. Fitting the model with
[30]
UV-visible data using the SPECFITprogram,
binding
constants could readily be extracted for complexes
[Cu(2)(1)]+ and [Cu2(2)(1)]2+. As depicted in Scheme 10 a
two step pathway is postulated for the basket assembly proc-
ess. Although the logb111 value is in the range of similar Cu+
species,[25] the logb211 value is relatively high, indicating the
cooperativity in the final step.
Molecular modelling was done with the MM+ force field as implement-
ed in Hyperchem 6.02.[23]
Spectrophotometric titrations: Equilibrium constants of complexes were
determined in dichloromethane. Macrocycle 1 and 2 were titrated with
aliquot amounts of a stock solution of copper(i) tetrakisacetonitrile hexa-
fluorophosphate. All stock solutions were prepared by careful weighing
on a mg analytical balance. Absorption spectra were recorded at 25.0ꢀ
(0.1)8C. Since the formation is instantaneous as evidenced by proton
NMR spectroscopy, ESI-MS analysis, and visible colour change, the solu-
tions were immediately analysed by the spectroscopy to avoid problems
with the volatile solvent. The wavelength region from 240 nm to 600 nm
was taken into account. Two equivalents (total) of metal salt in dichloro-
methane solution were added in 20 portions. The entire data sets com-
prising absorbances measured in one nanometer steps were decomposed
in their principal components by factor analysis, and subsequently the
formation constants including their standard deviation were calculated by
using the SPECFIT[30] program. Binding constants were determined from
two independent titrations.
Conclusions
We report the synthesis of the rigid nanoscale macrocycle 1,
its self-assembly behaviour at a solid–liquid interfaces and
its usage in building a heteroleptic supramolecular nanoscale
basket through self-assembly in solution. The presence of
two rigid exotopic bidentate chelating groups makes 1 a
useful building block to create nanoscale architectures. On
one side, STM shows highly ordered monolayers of the mac-
rocyclic system 1 at the solution–HOPG interface. On the
other side, there is a strong driving force for this macrocycle
to form selectively heteroleptic Cu+ and Ag+ complexes
with other phenanthrolines. The formation of these com-
plexes is confirmed by a multitude of spectroscopic techni-
ques (see Experimental Section). Most interesting is the for-
mation of a heteroleptic self-assembled basket-shaped ag-
gregate that shows up in three different isomeric structures.
The mechanistic investigations led to the proposal of a two
step pathway for the self-assembly process. In addition, the
conversion of the silver to the copper basket demonstrates
the system to be dynamic. Further studies are in progress to
study the interface behaviour of self-assembled structures of
1 with metal ions, host–guest properties of these assemblies
and the construction of higher order supramolecular aggre-
gates.
Synthesis of 7
3,8-Dihexyl-4,7-bis-{4-[(trisisopropylsilyl)ethynyl]phenylethynyl}-1,10-
phenanthroline (5a): Compounds 3[13] (1.00 g, 1.98 mmol) and 4 (1.73 g,
6.12 mmol), [PdCl2(PPh3)2] (150 mg, 210 mmol) and CuI (300 mg,
1.60 mmol) were placed in a dry flask and dry benzene (20 mL) and dry
triethylamine (10 mL) were added in an inert atmosphere. The resulting
dark solution was refluxed for 3 d and the solvent was removed under re-
duced pressure. The residual material was dissolved in dichloromethane
(50 mL) and washed with aqueous KCN (50 mL, 20%) and later by
water. The solvent was then removed under reduced pressure. The resi-
due was purified by column chromatography with dichloromethane and
subsequently ethyl acetate as eluents to afford 1.64 g (90%) of 5a as
yellow powder. M.p. 67–708C; 1H NMR (200 MHz): d=0.87 (t, J=
6.9 Hz, 6H; hexyl), 1.05 (s, 6H; triisopropyl), 1.15 (s, 36H; triisopropyl),
1.23–1.54 (m, 12H; hexyl), 1.72–1.90 (m, 4H; hexyl), 3.07 (t, J=6.6 Hz,
4H; hexyl), 7.53 (d, J=8.6 Hz, 4H; phenyl), 7.60 (d, J=8.6 Hz, 4H;
phenyl), 8.38 (s, 2H; phenanthroline), 9.04 ppm (s, 2H; phenanthroline);
13C NMR (50 MHz): d=11.3, 14.0, 18.7, 22.6, 29.2, 30.6, 31.6, 32.6, 85.7,
93.8, 101.9, 106.4, 122.2, 124.5, 125.1, 127.6, 127.7, 131.5, 132.2, 138.9,
144.4, 151.2 ppm; IR (KBr):=2941, 2863, 2204, 2153, 1560, 1508, 1459,
1420, 1382, 1232, 996, 882, 835, 677 cmꢁ1; elemental analysis calcd (%)
for C62H80N2Si2·H2O (927.52): C 80.29, H 8.91, N 3.02; found: C 80.21, H
8.62, N 3.14.
Experimental Section
4,7-Bis-(4-ethynylphenylethynyl)-3,8-dihexyl-1,10-phenanthroline
(5b):
Tetrabutylammoniumfluoride trihydrate (1.04 g, 3.30 mmol) in THF
(50 mL) was added to a solution of 5a (1.25 g, 1.35 mmol) in THF
(50 mL). The resulting mixture was stirred at room temperature for
30 min; then the reaction was quenched by the addition of water
(100 mL). The resulting solution was extracted with dichloromethane and
the combined organic layers were dried over MgSO4. The solvent was re-
moved under reduced pressure and the residue was purified by column
chromatography with dichloromethane and then ethyl acetate as eluents
to give 750 mg of 5b (92%) as ochre coloured crystals. M.p. 173–1748C;
1H NMR (200 MHz): d=0.87 (t, J=6.9 Hz, 6H; hexyl), 1.21–1.56 (m,
12H; hexyl), 1.73–1.95 (m, 4H; hexyl), 3.08 (t, J=7.5 Hz, 4H; hexyl),
3.23 (s, 2H; ethynyl), 7.55 (d, J=8.1 Hz, 4H; phenyl), 7.63 (d, J=8.1 Hz,
4H; phenyl), 8.39 (s, 2H; phenanthroline), 9.06 ppm (s, 2H; phenanthro-
line); 13C NMR (50 MHz): d=14.0, 22.5, 29.1, 30.5, 31.6, 32.6, 79.5, 83.0,
85.7, 101.6, 123.0, 124.9, 125.0, 127.5, 131.6, 132.2, 132.5, 139.0, 144.3,
151.1 ppm; IR (KBr):=3294, 3166, 2924, 2854, 2198, 2094, 1560, 1508,
1458, 1421, 1376, 1234, 1102, 893, 837, 754 cmꢁ1; elemental analysis calcd
(%) for C44H40N2·0.5H2O (605.83): C 87.23, H 6.82, N 4.62; found: C
87.16, H 7.23, N 4.68.
Starting materials 1,10-phenanthroline, ethynyltrimethylsilane, ethynyl-
triisopropylsilane, 2-bromo-1,3,5-trimethylbenzene, 2-bromo-5-methoxy-
1,3-dimethylbenzene, 4-bromophenylamine, activated MnO2 and 4-tert-
butylphenol were purchased from Aldrich, Merck or Lancaster and used
as received. [Pd(Ph3P)2Cl2],[31] [Pd(Ph3P)4],[32] 3,[13] 9,[15a] 11,[15b] (4-bromo-
phenylethynyl)trimethylsilane[34] and 5-tert-butyl-1,3-diiodo-2-methoxy-
benzene[35] were prepared according to the literature procedures. Stan-
dard inert atmosphere and Schlenk techniques were employed for all the
Heck reactions. Solvents were dried using typical drying procedures. 1H
NMR and 13C NMR spectra were measured on
a Bruker AC200
(200 MHz) or Bruker AMX600 (600 MHz). All the 1H NMR spectra
were carried out at room temperature in deuterotrichloromethane unless
specified otherwise. ESI MS was measured on an LCQ Deca Thermo
Quest instrument. Typically, each time 25 scans were accumulated for
one spectrum. UV-visible spectra were recorded on a Tidas II spectro-
photometer with dichloromethane as the solvent. For full characterisation
of 4 and its immediate precursor see reference [33]
STM at the solid–liquid interface[34] was performed by using a home-built
beetle-type STM interfaced with a commercial controller (Omicron).
STM tips were prepared by mechanically cutting a 0.25-mm thick Pt/Ir
(80%/20%) wire. A drop of an almost saturated solution of the macrocy-
cle in 1,2,4-trichlorobenzene was applied to the basal plane of freshly
cleaved highly oriented pyrolytic graphite (HOPG). The lattice of the un-
derlying substrate could be visualised during measurements by simply
4,7-Bis-[4-(5-tert-butyl-3-iodo-2-methoxyphenylethynyl)phenylethynyl]-
3,8-dihexyl-1,10-phenanthroline (7): A mixture of 5b (200 mg (330 mmol)
and 6[35] (1.56 g, 3.75 mmol), dry benzene (7 mL), dry triethylamine
(2 mL), and [Pd(PPh3)4] (200 mg, 170 mmol) was refluxed for 3 d. Then
the solvent was removed under reduced pressure. After taking up the res-
idue in dichloromethane (100 mL) it was washed with aqueous KCN
Chem. Eur. J. 2004, 10, 5481 – 5492
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ꢀ 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
5489

M. Schmittel et al.
FULL PAPER
(100 mL, 2%) and later with water. The organic layer was dried over
MgSO4 and the residual material subjected to column chromatography
with first dichloromethane and later methyl-tert-butylether as eluents to
give 340 mg of 7 (88%) as colourless powder. M.p. 208–2108C; 1H NMR
(200 MHz): d=0.89 (t, J=6.9 Hz, 6H; hexyl), 1.24–1.57 (m, 12H; hexyl),
1.31 (s, 18H; tert-butyl), 1.72–1.97 (m, 4H; hexyl), 3.09 (t, J=8.3 Hz, 4H;
hexyl), 4.02 (s, 6H; methoxy), 7.51 (d, J=2.3 Hz, 2H; phenyl), 7.62 (d,
J=8.6 Hz, 4H; phenyl), 7.69 (d, J=8.6 Hz, 4H; phenyl), 7.77 (d, J=
2.3 Hz, 2H; phenyl), 8.38 (s, 2H; phenanthroline), 9.05 ppm (s, 2H; phe-
nanthroline); 13C NMR (50 MHz): d=14.0, 22.5, 29.1, 30.6, 31.2, 31.6,
32.6, 34.2, 61.0, 85.8, 88.1, 91.7, 93.2, 101.7, 116.2, 122.4, 124.0, 125.0,
127.5, 130.9, 131.6, 131.7, 131.9, 137.2, 138.9, 144.4, 148.6, 151.2,
158.1 ppm; IR (KBr):=3054, 2924, 2855, 2202, 1560, 1509, 1466, 1435,
1420, 1256, 1097, 1000, 835, 746, 693 cmꢁ1; elemental analysis calcd (%)
for; C66H66I2N2O2 (1173.07): C 67.58, H 5.67, N 2.39; found: C 67.68, H
5.86, N 2.41.
3,5-Dimethyl-4-[9-(2,4,6-trimethylphenyl)-1,10-phenanthrolin-2-yl]phenol
(12): Pyridine (9 mL) was added to conc. HCl (10.5 mL) and the resultant
mixture was heated to reflux at 2008C (water was removed completely).
After cooling the mixture to 1408C, 10 (400 mg, 906 mmol) was added.
The mixture was heated to 215–2208C and kept there for 2.5 h. Subse-
quently, the mixture was cooled to 1308C and a solution of water
(20 mL) and conc. HCl (5 mL) was added affording a yellow solution.
After cooling to room temperature, the reaction mixture was extracted
several times with dichloromethane. The organic phases were combined,
washed with water and finally neutralised with conc. KOH. The organic
layer was dried over MgSO4 and the solvent was removed under reduced
pressure. The residue was then purified by column chromatography with
dichloromethane as eluent, furnishing 370 mg of 12 (96%) as a colourless
powder. M.p. >2808C; 1H NMR (200 MHz): d=1.90 (s, 6H; benzyl),
2.12 (s, 6H; benzyl), 2.29 (s, 3H; benzyl), 6.30 (s, 2H; phenyl), 6.91 (s,
2H; phenyl), 7.51 (d, J=8.1 Hz, 1H; phenanthroline), 7.58 (d, J=8.3 Hz,
1H; phenanthroline), 7.86 (s, 2H; phenanthroline), 8.23 (d, J=8.3 Hz,
1H; phenanthroline), 8.34 ppm (d, J=8.1 Hz, 1H; phenanthroline);
13C NMR (50 MHz): d=20.3, 20.4, 21.1, 114.8, 123.8, 124.7, 125.5, 125.6,
126.4, 126.8, 127.1, 128.2, 131.2, 135.4, 135.8, 136.1, 136.4, 137.7, 145.6,
146.0, 156.9, 160.5, 161.1 ppm; IR (KBr):=3258,.3033, 2952, 2917, 2856,
1614, 1586, 1542, 1479, 1318, 1159, 1101, 1033, 887, 857, 756, 636 cmꢁ1; el-
emental analysis calcd (%) for C29H26N2O·0.5H2O (427.55): C 81.47, H
6.37, N 6.55; found: C 81.21, H 6.67, N 6.34.
Synthesis of macrocycle 1: A solution of 7 (400 mg, 341 mmol) and 5b
(200 mg, 330 mmol) in dry benzene (20 mL) was added to a flask contain-
ing a mixture of [Pd(PPh3)4] (350 mg, 300 mmol), dry benzene (60 mL)
and dry triethylamine (20 mL) over a period of 32 h by means of an in-
jection pump, while keeping at reflux. The resulting dark solution was re-
fluxed for 8 h and the solvent was removed under reduced pressure. The
obtained dark residue was suspended in trichloromethane and washed
with aqueous KCN (100 mL, 2%). The aqueous phase was extracted sev-
eral times with trichloromethane. The combined organic phases were
evaporated to dryness under reduced pressure affording a residue which
was then extracted twice with hot n-hexane (2”20 mL) and dried under
reduced pressure. Subsequently, trichloromethane (5 mL) was added and
after one night at room temperature colourless thin needles resulted,
which were washed several times with trichloromethane to yield analyti-
cally pure 1 (80.0 mg, 16%). M.p. >3008C; 1H NMR (200 MHz, CDCl3/
5% TFA): d=0.93 (t, J=6.9 Hz, 12H; hexyl), 1.33–1.64 (m, 24H; hexyl),
1.40 (s, 18H; tert-butyl), 1.80–2.00 (m, 8H; hexyl), 3.25 (t, J=6.0 Hz, 8H;
hexyl), 4.30 (s, 6H; methoxy), 7.61 (s, 4H; phenyl), 7.72 (d, J=8.6 Hz,
8H; phenyl), 7.80 (d, J=8.6 Hz, 8H; phenyl), 8.74 (s, 4H; phenanthro-
line), 9.10 ppm (s, 4H; phenanthroline); 13C NMR (CDCl3/5% TFA,
50 MHz): d=13.9, 22.5, 29.2, 30.2, 31.2, 31.5, 32.8, 34.6, 62.1, 84.2, 88.6,
93.2, 109.8, 120.6, 126.0, 126.3, 126.4, 129.3, 131.3, 132.0, 132.5, 134.9,
135.0, 142.4, 146.8, 148.1, 160.1 ppm; IR (KBr):=3064, 3038, 2954, 2925,
Synthesis of 2: Anhydrous K2CO3 (300 mg, 2.17 mmol) was added at
room temperature and in an inert atmosphere to a solution of 12
(600 mg, 1.43 mmol) and 13[37] (410 mg, 610 mmol) in dry DMF (50 mL).
The resulting dark brown solution was stirred for 1 h at room tempera-
ture and then for 3 d at 60–708C. The solvent was evaporated under re-
duced pressure and taken up in a mixture of dichloromethane (100 mL)
and water (100 mL). The organic layers were washed with water and
dried over MgSO4, then the solvent was evaporated to dryness. The resi-
due was then subjected to column chromatography with first diethyl
ether and later ethyl acetate as eluents to afford 520 mg (69%) of a
beige powder. M.p. 87–898C; 1H NMR (200 MHz): d=2.14 (s, 12H;
benzyl), 2.15 (s, 12H; benzyl), 2.31 (s, 6H; benzyl), 3.65–3.78 (m, 8H;
ethoxy), 3.80–3.94 (m, 8H; ethoxy), 4.02–4.19 (m, 8H; ethoxy), 6.66 (s,
4H; phenyl), 6.85 (s, 4H; phenyl), 6.93 (s, 4H; phenyl), 7.55 (d, J=
8.1 Hz, 2H; phenanthroline), 7.57 (d, J=8.1 Hz, 2H; phenanthroline),
7.84 (s, 4H; phenanthroline), 8.26 (d, J=8.1 Hz, 2H; phenanthroline),
8.27 ppm (d, J=8.1 Hz, 2H; phenanthroline); 13C NMR (50 MHz): d=
20.5, 20.9, 21.0, 67.3, 68.1, 69.7, 69.8, 70.7, 70.8, 113.9, 115.6, 124.9, 125.2,
126.1, 127.0, 128.4, 134.0, 135.6, 136.1, 137.3, 137.9, 138, 146, 153.1, 158.1,
159.7, 160.1 ppm; IR (KBr):=3036, 2917, 2856, 1604, 1585, 1508, 1476,
1317, 1231, 1164, 1125, 1069, 857, 634 cmꢁ1; elemental analysis calcd (%)
for C76H78N4O8·3H2O (1229.52): C 74.24, H 6.89, N 4.56; found: C 74.50,
H 6.51, N 4.30.
2855, 2202, 1560, 1510, 1466, 1420, 1245, 1110, 1005, 880, 832, 752 cmꢁ1
ESI MS: m/z (%): 1515 (100) [M+H]+; elemental analysis calcd (%) for
110H104N4O2 (1514.06): C 87.26, H 6.92, N 3.70; found: C 87.08, H 7.11,
;
C
N 3.68.
2-(4-Methoxy-2,6-dimethylphenyl)-9-(2,4,6-trimethylphenyl)-1,10-phenan-
throline (10): n-Butyllithium (2.5m solution in hexane, 24.0 mL,
60.0 mmol) was added to a solution of 2-bromo-5-methoxy-1,3-dimethyl-
benzene (1.80 g, 8.37 mmol) in dry diethyl ether (20 mL) at 08C. The
yellow solution was stirred at room temperature for 1 h providing a col-
ourless turbid mixture. Compound 9[36] (1.00 g, 3.35 mmol) was then
added slowly under nitrogen atmosphere over 15 min. The solution
turned dark violet and was stirred for 18 h at room temperature. After
quenching the reaction with H2O (50 mL), the organic phase was separat-
ed. The aqueous phase layer was extracted with dichloromethane
(50 mL), and the combined organic phases were dried over magnesium
sulfate. The concentrated reaction mixture (volume: 50 mL) was subse-
quently oxidised with excess of activated MnO2 (10 g) for 1 h and filtered
through a pad of Celite with dichloromethane as eluent. After concentra-
tion of the filtrate the crude product was purified by column chromatog-
raphy with first dichloromethane and then diethyl ether to give a 770 mg
Synthesis of complex C1: Tetrakis(acetonitrile)copper(i) hexafluorophos-
phate (25.0 mg, 67.0 mmol) in dichloromethane (10 mL) was added to a
mixture of macrocycle
1
(50.7 mg, 33.5 mmol) and 11[15b] (28.0 mg,
67.0 mmol). The resulting dark red solution was heated for several sec-
onds, and the solvent was evaporated to give C1. After chromatography
(silica gel; dichoromethane/methanol=10:1) 40.0 mg (43%) of a dark
red powder were obtained. M.p. >3008C; 1H NMR (600 MHz, CD2Cl2):
d=0.90 (t, J=7.1 Hz, 12H; hexyl), 1.32–1.44 (m, 16H; hexyl), 1.38 (s,
18H; tert-butyl), 1.45–1.52 (m, 8H; hexyl), 1.72 (s, 12H; benzyl), 1.74 (s,
24H; benzyl), 1.77–1.85 (m, 8H; hexyl), 3.08 (t, J=6.9 Hz, 8H; hexyl),
4.27 (s, 6H; methoxy), 6.05 (s, 8H; phenyl), 7.58 (s, 4H; phenyl), 7.73 (d,
J=7.9 Hz, 8H; phenyl), 7.81 (d, J=7.9 Hz, 8H; phenyl), 7.82 (d, J=
8.1 Hz, 4H; phenanthroline), 8.27 (s, 4H; phenanthroline), 8.37 (s, 4H;
phenanthroline), 8.50 (s, 4H; phenanthroline), 8.74 ppm (d, J=8.1 Hz,
4H; phenanthroline); 13C NMR (CD2Cl2, 151 MHz): d=14.0, 20.0, 20.7,
22.5, 29.1, 30.7, 31.2, 31.6, 32.5, 34.4, 61.7, 84.7, 88.7, 92.9, 104.6, 116.5,
121.3, 125.1, 125.2, 126.4, 127.0, 127.9, 128.1, 131.0, 131.9, 132.1, 134.4,
137.0, 137.7, 137.8, 140.5, 141.4, 143.8, 146.7, 147.9, 158.7, 160.2 ppm; IR
(KBr):=2965, 2922, 2854, 2194, 1582, 1509, 1458, 1420, 1244, 1105, 1008,
840, 557 cmꢁ1; ESI MS: m/z (%): 1236.4 (100) [Mꢁ2PF6]+; elemental
analysis calcd (%) for C170H160N8O2Cu2P2F12 (2764.21): C 73.87, H 5.83, N
4.05; found: C 73.41, H 6.22, N 4.07.
1
of a colourless solid (52%) M.p. 2628C; H NMR (200 MHz): d=2.17 (s,
6H; benzyl), 2.20 (s, 6H; benzyl), 2.33 (s, 3H; benzyl), 3.82 (s, 3H; me-
thoxy), 6.68 (s, 2H; phenyl), 6.94 (s, 2H; phenyl), 7.57 (d, J=8.1 Hz, 1H;
phenanthroline), 7.58 (d, J=8.3 Hz, 1H; phenanthroline), 7.84 (s, 2H;
phenanthroline), 8.27 (d, J=8.1 Hz, 1H; phenanthroline), 8.28 ppm (d,
J=8.3 Hz, 1H; phenanthroline); 13C NMR (50 MHz): d=20.5, 20.9, 21.0,
55.1, 113.1, 124.9, 125.2, 126.1, 127.0, 128.4, 133.9, 135.6, 136.2, 137.3,
137.9, 138.1, 146.2, 158.9, 159.8, 160.1 ppm; IR (KBr):=2953, 2915, 1606,
1583, 1541, 1479, 1375, 1356, 1319, 1194, 1156, 1100, 1074, 1039, 885, 858,
634 cmꢁ1; elemental analysis calcd (%) for C30H28N2O·0.5H2O (441.56):
C 81.60, H 6.62, N 6.34; found: C 81.3, H 6.54, N 6.03.
Synthesis of complex C2: Compound 10 (33.9 mg, 78.3 mmol),
[Cu(CH3CN)4]PF6 (29.2 mg, 78.3 mmol), and macrocycle
1 (59.3 mg,
5490
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Supramolecular Nanobaskets
5481 – 5492
39.1 mmol) were stirred for 1 h in dichloromethane (10 mL). The resulting
dark red solution was evaporated to dryness to furnish C2. After chroma-
tography (silica gel; dichoromethane/methanol=10:1) 87.0 mg (80%) of
a dark red powder containing water were obtained. M.p. >3008C;
1H NMR (600 MHz, CD2Cl2): d=0.91 (t, J=7.2 Hz, 12H; hexyl), 1.33–
1.45 (m, 16H; hexyl), 1.40 (s, 18H; tert-butyl), 1.48–1.54 (m, 8H; hexyl),
1.73 (s, 12H; benzyl), 1.75 (s, 12H; benzyl), 1.81 (s, 12H; benzyl), 1.82–
1.86 (m, 8H; hexyl), 3.11 (t, J=7.5 Hz, 8H; hexyl), 3.34 (s, 6H; me-
thoxy), 4.27 (s, 6H; methoxy), 5.83 (s, 4H; phenyl), 6.07 (s, 4H; phenyl),
7.63 (s, 4H; phenyl), 7.77 (d, J=8.1 Hz, 8H; phenyl), 7.85 (d, J=8.1 Hz,
8H; phenyl), 7.86 (d, J=8.0 Hz, 2H; phenanthroline), 7.87 (d, J=8.0 Hz,
2H; phenanthroline), 8.25 (s, 4H; phenanthroline), 8.40 (s, 4H; phenan-
throline), 8.53 (s, 4H; phenanthroline), 8.72 (d, J=8.0 Hz, 2H; phenan-
throline), 8.73 ppm (d, J=8.0 Hz, 2H; phenanthroline); 13C NMR
(CD2Cl2, 151 MHz): d=14.2, 20.2, 20.6, 20.8, 23.0, 29.6, 31.1, 31.3, 32.0,
33.0, 34.7, 55.0, 62.0, 85.3, 89.1, 93.1, 104.8, 112.0, 116.9, 122.0, 125.5,
125.6, 126.9, 127.1, 127.4, 128.4, 128.5, 128.6, 131.6, 132.3, 132.5, 133.1,
134.9, 136.7, 137.5, 137.9, 138.3, 141.2, 141.9, 144.4, 147.4, 148.5, 159.2,
159.3, 159.5, 160.6 ppm; IR (KBr):=2954, 2923, 2855, 2195, 1654, 1570,
1508, 1475, 1458, 1420, 1320, 1245, 1156, 1104, 1011, 839, 558 cmꢁ1; ESI
MS: m/z (%): 1253.2 (100) [Mꢁ2PF6]+; elemental analysis calcd (%) for
C170H160N8O4Cu2P2F12·3H2O (2796.21): C 71.64, H 5.87, N 3.93; found: C
71.75, H 5.93, N 4.29.
(m, 8H; phenyl), 7.93 (d, J=8.2 Hz, 2H; phenanthroline), 8.21 (d, J=
9.3 Hz, 2H; phenanthroline; HX6’), 8.24 (d, J=9.3 Hz, 2H; phenanthro-
line; HX6’), 8.40 (s, 4H; phenanthroline), 8.52 (s, 4H; phenanthroline),
8.70 (d, J=8.0 Hz, 2H; phenanthroline), 8.74 ppm (d, J=8.2 Hz, 2H;
phenanthroline); 13C NMR (CD2Cl2, 151 MHz): d=14.0, 20.0, 20.3, 20.4,
23.0, 29.1, 29.3, 30.9, 31.7, 32.7, 34.5, 61.7, 66.7, 68.0, 68.1, 69.3, 70.5, 70.9,
85.0, 88.9, 92.8, 104.6, 111.8, 115.5, 116.6, 121.7, 125.2, 125.4, 126.8, 126.9,
127.3, 128.0, 128.1, 128.3, 131.4, 132.0, 132.2, 132.6, 132.9, 134.7, 136.2,
136.4, 137.5, 137.6, 138.1, 140.9, 141.6, 144.1, 147.2, 148.2, 153.2, 153.3,
157.8, 158.7, 160.3 ppm.
Isomer C4y: 1H NMR (600 MHz, CD2Cl2): d=0.88–0.93 (m, 12H;
hexyl), 1.32–1.45 (m, 16H; hexyl), 1.38 (s, 18H; tert-butyl), 1.47–1.56 (m,
8H; hexyl), 1.70 (s, 12H; benzyl), 1.74 (s, 6H; benzyl), 1.80–1.86 (m, 8H;
hexyl), 1.99 (s, 12H; benzyl), 3.02–3.20 (m, 8H; hexyl), 3.61–3.62 (m,
4H; ethoxy), 3.63–3.65 (m, 4H; ethoxy), 3.70–3.72 (m, 4H; ethoxy),
3.78–3.80 (m, 4H; ethoxy), 3.89–3.90 (m, 4H; ethoxy), 3.96–3.98 (m, 4H;
ethoxy), 4.14 (s, 6H; methoxy; HYc), 5.49 (s, 4H; phenyl; HYb), 6.33 (s,
4H; phenyl; HYa), 7.07 (s, 4H; phenyl; HYc), 7.62 (s, 4H; phenyl), 7.74–
7.76 (m, 8H; phenyl), 7.77 (d, J=8.1 Hz, 2H; phenanthroline), 7.87–7.88
(m, 8H; phenyl), 7.97 (d, J=8.2 Hz, 2H; phenanthroline), 8.21 (d, J=
9.3 Hz, 2H; phenanthroline; HY6’), 8.24 (d, J=9.3 Hz, 2H; phenanthro-
line; HY5’), 8.40 (s, 4H; phenanthroline), 8.55 (s, 4H; phenanthroline),
8.67 (d, J=8.1 Hz, 2H; phenanthroline), 8.76 ppm (d, J=8.2 Hz, 2H;
phenanthroline); 13C NMR (CD2Cl2, 151 MHz): d=13.9, 20.1, 20.3, 20.4,
23.0, 29.1, 29.3, 30.9, 31.7, 32.7, 34.5, 61.6, 66.6, 69.8, 70.5, 70.8, 71.2, 71.3,
85.0, 88.9, 92.8, 104.6, 111.5, 115.7, 116.6, 121.8, 125.3, 125.4, 126.8, 127.6,
128.0, 128.1, 128.3, 131.3, 132.0, 132.2, 132.6, 132.9, 134.7, 136.2, 136.4,
137.5, 137.8, 138.1, 140.9, 141.6, 144.1, 147.2, 148.2, 153.2, 153.3, 157.8,
159.3, 160.4 ppm.
Synthesis of complex C3: Compound 2 (49.0 mg, 40.9 mmol), 5a (74.4 mg,
81.8 mmol) and [Cu(CH3CN)4]PF6 (30.5 mg (81.8 mmol) were stirred in
dry dichloromethane (10 mL) for 2 h. The resulting dark red solution was
evaporated to afford crude C3. After chromatography (silica gel; di-
choromethane/methanol=10:1) 130 mg (85%) of a dark red powder con-
taining dichloromethane were obtained. M.p. >122–1248C; 1H NMR
(600 MHz, CD2Cl2): d=0.86–0.90 (m, 12H; hexyl), 1.15–1.20 (m, 84H;
triisopropyl), 1.31–1.40 (m, 16H; hexyl), 1.43–1.49 (m, 8H; hexyl), 1.70–
1.72 (m, 6H; benzyl), 1.72–1.74 (m, 12H; benzyl), 1.77–1.82 (m, 8H;
hexyl), 1.79 (s, 12H; benzyl), 3.07 (t, J=7.6 Hz, 8H; hexyl), 3.55–3.56 (m,
4H; ethoxy), 3.57 (s, 4H; ethoxy), 3.58 (s, 4H; ethoxy), 3.60–3.68 (m,
4H; ethoxy), 3.69–3.81 (m, 4H; ethoxy), 3.95–4.05 (m, 4H; ethoxy), 5.84
(s, 4H; phenyl), 6.02–6.06 (m, 4H; phenyl), 6.75–6.80 (m, 4H; phenyl),
7.59–7.63 (m, 8H; phenyl), 7.71–7.74 (m, 8H; phenyl), 7.85–7.94 (m, 4H;
phenanthroline), 8.24 (s, 4H; phenanthroline), 8.38–8.40 (m, 4H; phenan-
throline), 8.47–8.52 (m, 4H; phenanthroline), 8.70–8.74 ppm (m, 4H;
phenanthroline); 13C NMR (151 MHz): d=11.7, 14.2, 18.8, 20.3, 20.6,
20.8, 23.0, 29.6, 31.1, 32.0, 33.0, 67.2, 68.3, 69.8, 70.1, 71.0, 71.1, 85.2, 94.9,
104.7, 106.6, 112.6, 115.7, 122.0, 125.6, 127.0, 127.2, 127.4, 128.3, 128.4,
128.6, 129.1, 132.2, 132.7, 133.3, 134.8, 136.7, 137.4, 137.9, 138.2, 141.4,
141.9, 144.4, 148.4, 153.4, 158.3, 159.2, 159.4 ppm; IR (KBr):=2924, 2862,
2198, 2152, 1618, 1578, 1542, 1508, 1458, 1376, 1232, 1164, 1124, 1071,
839, 747, 557 cmꢁ1; ESI MS: m/z (%): 1560.3 (100) [Mꢁ2PF6]+; elemen-
tal analysis calcd (%) for C200H238N8O8Si4Cu2P2F12·4CH2Cl2 (3751.23): C
65.40, H 6.62, N 2.99; found: C 65.11, H 6.44, N 2.90.
1
Isomer C4z: H NMR (400 MHz, CD2Cl2): d=0.79–0.83 (m, 12H; hexyl),
1.32–1.45 (m, 16H; hexyl), 1.38 (s, 18H; tert-butyl), 1.47–1.56 (m, 8H;
hexyl), 1.70 (s, 12H; benzyl), 1.74 (s, 6H; benzyl), 1.80–1.86 (m, 8H;
hexyl), 1.99 (s, 12H; benzyl), 2.91–3.01 (m, 8H; hexyl), 3.61–3.62 (m,
4H; ethoxy), 3.63–3.65 (m, 4H; ethoxy), 3.70–3.72 (m, 4H; ethoxy),
3.78–3.80 (m, 4H; ethoxy), 3.89–3.90 (m, 4H; ethoxy), 3.96–3.98 (m, 4H;
ethoxy), 4.24 (s, 6H; methoxy; Hza), 5.85 (s, 4H; phenyl; HZb), 6.06 (s,
4H; phenyl), 6.75 (s, 4H; phenyl; HZc), 7.61 (s, 4H; phenyl), 7.75–7.77
(m, 8H; phenyl), 7.77 (d, J=8.1 Hz, 2H; phenanthroline), 7.87–7.88 (m,
8H; phenyl), 7.97 (d, J=8.2 Hz, 2H; phenanthroline), 8.21 (d, J=9.3 Hz,
2H; phenanthroline; HZ5’), 8.23 (s, 2H; phenanthroline; HZ6’), 8.38 (s,
4H; phenanthroline), 8.53 (s, 4H; phenanthroline), 8.67 (d, J=8.1 Hz,
2H; phenanthroline), 8.76 ppm (d, J=8.2 Hz, 2H; phenanthroline).
Acknowledgement
We are indebted to the financial support from the DFG, the Fonds der
Deutschen Chemie and the European Union (MAC-MES).
Preparation of heteroleptic basket assembly C4: Tetrakis(acetonitrile)-
copper(i) hexafluorophosphate (12.0 mg, 32.2 mmol) in dichloromethane
(10 mL) was added to a mixture of 1 (24.2 mg, 16.1 mmol) and 2 (18.7 mg,
16.1 mmol). The resulting dark red solution was heated (~358C) for sever-
al seconds and then the solvent was evaporated to afford the basket as-
sembly (C4xyz) quantitatively as dark red powder (containing water). M.p.
2258C; IR (KBr):=2924, 2855, 2195, 1605, 1509, 1462, 1260, 1101, 1026,
839, 555 cmꢁ1; ESI MS (C4xyz): m/z (%): 1408.4 (100) [Mꢁ2PF6]+; ele-
mental analysis calcd (%) for C186H182N8O10Cu2P2F12·2H2O (3142.59): C
71.09, H 5.97, N 3.57; found: C 71.02, H 5.89, N 3.46. C4x:C4y:C4z were
formed in a 59:24:17 ratio. C4x,y could be separated from C4z by chro-
matography (silica gel, dichloromethane/methanol=100:1). Initial frac-
tions contained C4x,y as the sole products while later fractions furnished
enriched C4z (80%).
Isomer C4x: 1H NMR (600 MHz, CD2Cl2): d=0.88–0.93 (m, 12H;
hexyl), 1.32–1.45 (m, 16H; hexyl), 1.39 (s, 18H; tert-butyl), 1.47–1.56 (m,
8H; hexyl), 1.58 (s, 6H; benzyl), 1.68 (s, 12H; benzyl), 1.80–1.86 (m, 8H;
hexyl), 1.87 (s, 12H; benzyl), 3.02–3.20 (m, 8H; hexyl), 3.50–3.52 (m,
4H; ethoxy), 3.53–3.56 (m, 4H; ethoxy), 3.57–3.59 (m, 4H; ethoxy),
3.69–3.70 (m, 4H; ethoxy), 4.01–4.02 (m, 4H; ethoxy), 4.16–4.20 (m, 4H;
ethoxy), 4.21 (s, 6H; methoxy; HXd), 5.64 (s, 4H; phenyl; HXb), 6.19 (s,
4H; phenyl; HXa), 6.87 (s, 4H; phenyl; HXc), 7.63 (s, 4H; phenyl), 7.76–
7.77 (m, 8H; phenyl), 7.83 (d, J=8.0 Hz, 2H; phenanthroline), 7.84–7.86
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5492
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www.chemeurj.org
Chem. Eur. J. 2004, 10, 5481 – 5492