Supramolecular copper phenanthroline racks: Structures, mechanistic insight and dynamic nature

Article abstract of DOI:10.1002/ejic.200400899

Herein, we describe the preparation of several dynamic multicomponent supramolecular racks based on copper phenanthroline complexes using the HETPHEN concept (heteroleptic bisphenanthroline complexes). This approach employs bulky aryl substituents at the

Full text of DOI:10.1002/ejic.200400899

FULL PAPER
Supramolecular Copper Phenanthroline Racks: Structures, Mechanistic Insight
and Dynamic Nature
Venkateshwarlu Kalsani,[a] Heinrich Bodenstedt,[a] Dieter Fenske,[b] and
Michael Schmittel*[a]
Keywords: Rack / HETPHEN / Self-assembly / Phenanthroline / Dynamics
Herein, we describe the preparation of several dynamic
multicomponent supramolecular racks based on copper
phenanthroline complexes using the HETPHEN concept
(heteroleptic bisphenanthroline complexes). This approach
employs bulky aryl substituents at the bisimine coordination
sites to control the coordination equilibrium. The racks were
characterised by spectroscopic methods, both in solution (1H
NMR, ESI-MS, UV/Vis, vapour pressure osmometry) and in
the solid state (X-ray). Ligand exchange studies established
the reversible nature of the aggregates, the details of which
are vital for the development of higher level multicomponent
structures. In this regard, the present rack assemblies con-
trast to the large multitude of known rack motifs that are
almost exclusively built using kinetically inert coordination
building blocks.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
nation with another rigid ligand the arrested ligand can
combine to a heteroleptic rack-pseudorotaxane motif fol-
lowing the maximum site occupancy principle.[1d] A much
easier way to dynamic multicomponent racks, however,
should emerge from the HETPHEN[5] approach (strategy
B). We have recently utilised the HETPHEN concept to es-
tablish heteroleptic bisphenanthroline copper complexes as
building blocks for large nanostructures.[6] In our approach,
heteroleptic aggregation is driven by steric and electronic
factors which do not require an endotopic macrocycle. In-
stead, steric stoppers are required at the 2,9-positions of
one of the bisimine coordination sites to prevent any homo-
leptic combination with itself. Therefore, in combination
with another bisimine ligand only hetero combinations will
result. This opens a much more facile way to heteroleptic
dynamic aggregation than in previous reports.[7]
We have recently disclosed some preliminary results on
dynamic rack structures in the context of our work on
supramolecular nanogrids.[8] Herein, we now detail the po-
tential of the HETPHEN[9] concept as a general strategy for
the construction of multicomponent dynamic racks, provide
structural insight into products and intermediates, and in-
terrogate the dynamic nature of these unique assemblies.
Introduction
Metallo-rack structures have a high standing in the bur-
geoning field of supramolecular chemistry due to their spa-
tially well-defined linear array of metal ions that is attract-
ive for many purposes, such as photoactive and electroac-
tive nanowires.[1] Therefore, facile and quantitative access
to rack aggregates is the goal of current research efforts.[1]
Racks, however, by their very nature are multi-component
structures that are most conveniently assembled under kin-
etic control, cf. the use of kinetically stable ruthenium coor-
dination complexes,[1b,1c,1e–1g] even at the price of moderate
yields. Preparation of rack structures under thermodynamic
control is much more a challenge since in a dynamic
multitopic aggregation scenario the requested heteroleptic
combinations have to compete with homoleptic ones.[1d] Re-
wardingly, dynamic aggregation should allow for self-repair
thus securing the most stable complex in very high yields if
sufficient thermodynamic bias is installed.[2] Once the proof
of principle is established one is set up to construe dynamic
aggregates at surfaces that should be very useful for sensory
purposes.[3]
At present, only one strategy is known to construct dy-
namic multicomponent rack structures (Scheme 1; strategy
A).[4] Accordingly, ring constraints are utilised to prevent
the formation of the homoleptic combination of one of the
ligands, e. g. of an endotopic macrocyclic ligand. In combi-
Results and Discussion
Following the HETPHEN concept two approaches can
be explored to prepare dynamic rack-type aggregates
(Scheme 2). In both approaches one set of the ligand has to
be instructed with the steric stoppers. In approach I, the
linear bisphenanthroline is loaded with sterically bulky aryl
[a] Center of Micro- and Nanochemistry and Engineering, Or-
ganische Chemie I, Universität Siegen,
Adolf-Reichwein-Str., 57068 Siegen, Germany
Fax: +49-271-740-3270
[b] Institut für Anorganische Chemie, Universität Karlsruhe,
Engesserstr. 3045, 76128 Karlsruhe, Germany
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DOI: 10.1002/ejic.200400899
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V. Kalsani, H. Bodenstedt, D. Fenske, M. Schmittel
FULL PAPER
Scheme 1. Strategies to prepare dynamic rack-type motifs.[1d]
Scheme 2. Two different approaches for constructing dynamic multitopic rack-type motifs along the HETPHEN concept (in the bottom:
a pictorial cartoon representation of the two approaches).
groups at the 2,9-positions of each phenanthroline site. In in presence of metal ions of tetrahedral coordination geom-
contrast, approach II makes use of monophenanthrolines etry, such as copper(i) or silver(i) ions, is expected to yield
that are equipped with the steric stoppers, while the linear the desired dynamic multicomponent racks.
bisphenanthroline is devoid of them.
To illustrate the need for control in the formation of dy-
The linear bisphenanthrolines 1a,[10] 1b[10] and 2,[11] as namic rack assemblies using a coordination approach bi-
well as the monophenanthrolines 3a, 3b,[13] 4a,[6c] 4b[12] and sphenanthroline 1a was treated with 3a in the presence of
4c[13] were chosen for this study. Assembly of 1,2 with 3,4 [Cu(MeCN)4]PF6. The desired rack was obtained only as a
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Supramolecular Copper Phenanthroline Racks
FULL PAPER
and CuI salt should result in heteroleptic racks.[8] Indeed,
upon addition of [Cu(MeCN)4]PF6 to a dichloromethane
solution of 2 and 3 the rack structures R1,R2 were exclu-
1
sively furnished as demonstrated by H NMR, 13C NMR,
ESI-MS, and elemental analysis.
Mechanistic Tests on the Formation of [Cu2(2)]2+. Rack
R1 [Cu2(2)(3a)2]2+ was selected as a model system and its
formation systematically investigated using a variety of
1
spectroscopic techniques (by, H NMR, ESI-MS and spec-
trophotometric titrations). Treatment of ligand 2 with 2
equiv. of [Cu(MeCN)4]PF6 resulted in a yellow solution, the
analysis of which by UV/Vis (absence of a MLCT band at
430–550 nm of a [Cu(phenanthroline)2]+ complex), ESI-MS
and 1H NMR suggested the formation of [Cu2(2)(Me-
CN)2]2+ as the sole species. As expected, ligand 2 acts as
a HETPHEN ligand that is not able to self-assemble to a
homoleptic grid.
1
minor component as evidenced by ESI-MS and H NMR
spectroscopy. Rather, a complex mixture formed showing
signals corresponding to the triangular-grid and signals
corresponding to the homoleptic complex of 3a as depicted
in Scheme 3. 1H NMR showed various sets of signals which
arise from the resulting different aggregates. It is clear from
the above experiment that cooperativity7 can not be used
solely to build dynamic heteroleptic aggregates.
Progressive addition of [Cu(MeCN)4]PF6 to 2 (in dichlo-
romethane) provided valuable information about the inter-
1
mediates as they could be readily detected by ESI-MS, H
NMR, and UV/Vis spectroscopy. In the 1H NMR spec-
trum, for example, the mesityl protons Mes-H can be used
as a diagnostic marker to assign the composition of the
intermediate species present in the equilibrium. Addition of
CuI salt to 2 in dichloromethane resulted in two new sets
of signals, one of which built up at the initial stage of the
titration and disappeared as the titration proceeded. The
Approach I
As discussed above, approach I uses a bisphenanthroline first set of signals, formed during addition of the first equiv.
that has steric stoppers (as in ligand 2) in combination with of CuI salt, was assigned to [Cu(2)(MeCN)]+. After ad-
any phenanthroline with no steric stoppers at 2,9-positions dition of 2 equiv. of CuI salt a single set of signals resulted
(i.e. 3a–3b). The combination of these two building blocks which could be readily assigned to [Cu2(2)(MeCN)2]2+. Im-
Scheme 3. Cartoon representation of the self-assembly of linear bisphenanthrolines and monophenanthrolines that are not instructed
along the HETPHEN concept.
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portantly, during the whole process no signals were detect- Table 1. Selected Bond Lengths [Å] and Angles [°] for [Cu2(2)(-
2+
MeCN)2]
.
able at 5–6 ppm, which is considered to be a characteristic
range for mesityl protons of a [Cu(phenanthroline)2]+ com-
plex.[9] ESI-MS titration results further supported the above
assignments.
Bond
Length [Å]
Angle
Angle [°]
N1–Cu1
N2–Cu1
2.016(17)
2.050(9)
1.856(18)
2.071(7)
2.017(21)
1.861(20)
N1–Cu1–N5
N2–Cu1–N5
N2–Cu1–N1
N3–Cu2–N6
N4–Cu2–N6
N3–Cu2–N4
146.14(1)
130.10(1)
82.91(2)
131.88(1)
142.61(2)
82.54(2)
The UV/Vis titration revealed the absence of a band at N5–Cu1
N3–Cu2
ca. 500 nm, indicating that formation of a [Cu(phenanthro-
N4–Cu2
line)2]+ complex with its characteristic MLCT had not oc-
N6–Cu2
curred. These results indicate that in line with the behaviour
of monophenanthroline analogs[9] ligand 2 has been suc-
cessfully instructed not to assemble with itself.
species (Figure 2). The distinct high field shifts for the me-
sitylene protons (6.76 to 5.89 ppm) of 2 clearly indicated
the formation of a bisheteroleptic complex.
Most convincingly the structure of [Cu2(2)(MeCN)2]2+
was supported by a single crystal structure analysis (Fig-
ure 1). It is worthwhile to note that, though the present sys-
tem is a simple one, the solid state characterisation of such
an intermediate in a coordination equilibrium is quite
unique. [Cu2(2)(MeCN)2]2+ has neither a syn or anti confor-
mation with regard to the two phenanthroline binding sites.
Instead, the two sites comprise a dihedral angle of ca. 122
deg. Each copper(i) center is coordinated to one phenan-
throline and a single acetonitrile molecule. The average Cu–
Nphen bond length is 204 3 pm, while the Cu–NMeCN dis-
tance is much shorter with 186 pm (Table 1). In conclusion,
1
the solid-state structure along with the H NMR, ESI-MS
and UV/Vis studies proves unequivocally that the
HETPHEN concept allows to control the coordination
equilibrium of specially designed phenanthroline ligands
and to prevent formation of any bishomoleptic complex
formation.
Figure 2. 1H NMR changes in the aromatic region of 2 upon com-
plexation with 3a. a) free 2; b) [Cu2(2)(MeCN)2]2+; c) [Cu2(2)-
(3a)2]2+. Signals in Figure c being marked by filled spheres belong
to phenanthroline (3a) protons.
For further understanding, a titration was performed, in
which 3a was added to a dichloromethane solution of [Cu2-
(2)(MeCN)2]2+ leading to pronounced changes in the 1H
NMR spectra. With the titration proceeding, two different
sets of signals evolved for the mesityl protons that were
readily assigned to [Cu(2)(3a)]+ and [Cu2(2)(3a)2]2+ using
1
parallel ESI-MS results. While ESI-MS and H NMR ti-
trations proposed a qualitative picture of the mechanism of
the self-assembly process, a UV/Vis titration was under-
taken to determine the binding constants. It was performed
by titrating 2 (1.210–6 m) and 3a (2.410–6 m) with aliquot
Figure 1. a) Space filling and b) stick representation of the crystal
2+
structure of [Cu2(2)(MeCN)2]
.
Mechanistic Tests on Formation of [Cu2(2)(3a)2]2+. Upon amounts of CuI solution in 20 additions (total 4 equiv. of
addition of a second phenanthroline, such as 3a or 3b, to Cu+). Figure 3 displays the UV/Vis changes upon CuI salt
the intermediate [Cu2(2)(MeCN)2]2+ in dichloromethane, addition showing the emerging MLCT transition at ca.
the racks R1 or R2 were afforded in basically quantitative 490 nm that is responsible for the red color. As shown in
1
yield as evidenced by H-NMR and ESI-MS. For example, Scheme 4 a two step pathway seems most reasonable for the
in case of R1 ESI-MS showed the presence of one single rack assembly process: it starts out with the formation of
species at m/z = 814.5 which corresponds to R12+. Equally, [Cu(2)(3a)]+ taking up one more ligand 3a and CuI to fur-
1
the H-NMR illustrated the presence of a single symmetric nish the [Cu2(2)(3a)2]2+ complex. The structure of
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Supramolecular Copper Phenanthroline Racks
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[Cu2(2)(3a)2]2+ was confirmed by its single crystal analy-
sis.[8] Upon fitting this model with UV/Vis data using the
SPECFIT program[14] binding constants could readily be
extracted for complexes [Cu(2)(3a)]+ (log K111 = 11.6) and
[Cu2(2)(3a)2]2+ (log β212 = 23.1). Models that did not fit
were rejected.
Scheme 5.
Apart from conventional characterisation techniques (1H
NMR, ESI-MS, UV/Vis, and elemental analysis), vapour
pressure osmometry (VPO) was applied to characterise R3
as one of the aggregates. VPO is a very useful method to
analyse self assembled systems even if they are dynamic;[15]
unfortunately, this technique has not been utilised fre-
quently. For R3 VPO provided a molar mass of 2417 Da,
which is in excellent agreement (–2%) with the mass ob-
tained from ESI-MS (2473). The characterisation of even
larger dynamic structures by VPO is currently under investi-
gation in our laboratory.
Figure 3. Spectrophotometric titration of 2 and 1,10-phenan-
throline (3a) by aliquot amounts of CuI salt in 20 additions. Sol-
vent: dichloromethane. T = 25(1) °C. [2] = 1.20×10–6 m and [3a] =
2.40×10–6 m.
The structure of R6 was solved by single-crystal X-ray
analysis. The stick representation of the solid-state structure
of R6 is depicted in Figure 4. Unlike a previous structure[8]
this rack has some deviation from prefect transoid confor-
mation. Each copper(i) centre exhibits a pseudotetrahedral
coordination geometry (N1–Cu1–N4 108.4°, N2–Cu1–N3
125.0°, N5–Cu2–N8 123.1°, N6–Cu2–N7 120.1°) and finds
itself encapsulated by two bromoduryl rings of the bisphen-
anthroline (Table 2). The duryl groups of 4a and the phen-
Scheme 4. Self-assembly path for R1.
Figure 4. Single crystal structure of R6; stick representation.
Table 2. Selected bond lengths [Å] and angles [°] for R6.
Approach II
Bond
Length [Å] Angle
Angle (in degrees)
As suggested above, rack motifs should also be accessible
by approach II. 4a–c were designed according to the
HETPHEN strategy, i.e. the 2,9-positions of all monophen-
anthrolines were loaded with steric stoppers while bisphen-
anthroline 1a and 1b were devoid of this element. Notably,
racks R3–R5 were readily afforded upon reacting 1a with
4a–c in presence of [Cu(MeCN)4]PF6 (Scheme 5). Similarly,
R6 was obtained by reacting 1b, 4a and CuI salt in dichloro-
methane (1:2:2 equiv.). All spectroscopic data was consis-
tent with the proposed composition (see experimental sec-
tion).
Cu1–N4
Cu1–N3
Cu1–N2
Cu1–N1
N2–Cu1–N1
N3–Cu1–N1
Cu2–N8
Cu2–N7
Cu2–N5
1.998
2.038
2.063
2.092
81.0(5)
135.0(4)
2.062
2.006
2.029
2.069
N4–Cu1–N2
131.9(4)
81.5(4)
125.0(4)
108.0(4)
N4–Cu1–N3
N2–Cu1–N3
N4–Cu1–N1
N7–Cu2–N8
N7–Cu2–N6
N8–Cu2–N6
N7–Cu2–N5
N8–Cu2–N5
N6–Cu2–N5
80.0(5)
119.5(4)
127.5(4)
129.0(4)
123.0(4)
82.5(4)
Cu2–N6
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V. Kalsani, H. Bodenstedt, D. Fenske, M. Schmittel
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anthroline plane of the second ligand 1b are oriented face- gand exchange between R3 and R4 by using ESI-MS, with
to-face separated by 3.5 Å, suggesting π-stacking.
ligand 1a being common in both R3 and R4 (Scheme 6).
1H NMR experiments on the R3 + R4 w R7 equilibration
could not be performed due to signal overlap. However, the
present example was studied by ESI-MS furnishing sensible
insight into the dynamics of such aggregates. Such investi-
gations are very informative when NMR application is lim-
ited.
Dynamic Nature of Rack Motifs
The dynamic nature of the rack motifs was tested by an
exchange experiment.[16] Specifically, we monitored the li-
R3 and R4 in dry dichloromethane were reacted in a 1:1
stoichiometric ratio. The ligand exchange process was ob-
served readily (within ca. 5 min) by ESI-MS exhibiting sig-
nals corresponding to a mixture of the three racks R3, R4
and R7 in a %-ratio of 55, 55 and 100, respectively. This
ratio did not change after longer times, indicating that equi-
librium had been established at room temp. within less than
5 min (Figure 5). Analgous results were obtained when the
racks were generated in one pot by reacting 1a, 4a and 4b
in presence of CuI salt. Isotopic distributions of R3, R4 and
R7 were in excellent agreement with the calculated ones.
The composition was further confirmed by collisional
fragmentation experiments. At higher voltages and tem-
perature the ESI-MS is dominated by [Cu(4a or 4b)(1a)]+
Scheme 6. Cartoon representation of ligand exchange equilibrium
in solution after mixing R3 and R4.
Figure 5. ESI-MS of the reaction mixture obtained when 1a, 4a, 4b are treated with CuI salt in dichloromethane.
Scheme 7. Mechanism of the dynamic ligand exchange in the interconversion of racks.
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Supramolecular Copper Phenanthroline Racks
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and [Cu(4a or 4b)]+ as fragments. It is interesting to note
that a similar behaviour was observed for all rack struc-
tures, i.e. it is always the sterically loaded ligand that is
bound to the metal ion in fragmentation processes. Presum-
ably due to cation-π interactions between Cu+ and 2,9-aryl
groups complexes [Cu(4a or 4b)]+ are more stable than
other combinations. These findings were corroborated
through collisional fragmentation experiments of R3, R4
and R7. For example, fragmentation of R4 produced signals
corresponding to the [Cu(4b)(1a)]+ and [Cu(4b)]+ species.
If we translate these ESI-MS results onto the equilibration
process in solution then it is reasonable to assume that in
the dynamic ligand exchange any dissociation occurs with
the metal ions attached to the sterically shielded
HETPHEN ligands (Scheme 7).
vent. The wavelength region from 240 nm to 600 nm was taken into
account. Two equivalents (total) of metal salt in dichloromethane
solution were added in 20 portions. The entire data sets comprising
absorbances measured with one nanometer resolution were decom-
posed in their principal components by factor analysis. Sub-
sequently, formation constants and their standard deviations were
calculated by using the SPECFIT[14] program. Binding constants
were determined from two independent titrations.
Vapor-Pressure Osmometry: The instrument (EuroOsmo 7000) was
operated at 27 °C, dry dichloromethane was used as solvent. Cali-
bration was performed by using tetrabutylammonium hexafluoro-
phosphate as standard.
General Procedure for the Preparation of Racks R1–R6: Racks R1–
6 were prepared by mixing 1 (or 2) and 3 (or 4) with [Cu(Me-
CN)4]PF6 (1:2:2 equiv., respectively) in dichloromethane. The re-
sulting dark red compound was analysed without any further puri-
fication by ESI-MS, 1H NMR, COSY, 13C NMR, IR and elemental
analysis.
Conclusions
[Cu2(2)(3a)2](PF6)2 (R1): M.p. Ͼ 300 °C. 1H NMR (CD2Cl2,
400 MHz): δ = 8.81 (s, 2 H, phen), 8.73 (d, J = 8.1 Hz, 2 H, phen),
8.40–8.50 (m, 8 H, phen), 8.23 (dd, 4 H, J = 8.1, J = 4.0 Hz, phen),
7.94 (s, 4 H, phen), 7.92 (d, J = 8.1 Hz, 2 H, phen), 7.75 (m, 4 H,
phen), 6.93 (s, 4 H, phenyl), 6.03 (s, 4 H, mes), 1.81 (s, 12 H, CH3),
1.59 (s, 12 H, CH3), 1.57 (s, 18 H, CH3). 13C NMR (CD2Cl2,
100 MHz): δ = 161.3, 159.9, 148.1, 144.3, 143.2, 142.9, 139.9, 139.1,
138.2, 138.1, 136.9, 135.0, 134.1, 133.6, 132.5, 131.9, 129.2, 129.1,
128.7, 128.1, 127.9, 127.6, 127.3, 125.1, 122.9, 122.5, 117.5, 117.1
(arom.); 96.7, 87.7 (ethynyl); 20.6, 20.3 (2C), 18.5 (aliph.). IR
In summary, the HETPHEN concept proves its value for
the clean preparation of racks R1–R6 from various bi-
sphenanthrolines and monophenanthrolines in presence of
Cu+. X-ray and solution spectroscopic data, including ESI-
MS, UV/Vis titrations and vapour pressure osmometry, dis-
close a clear picture of the self-assembly pathway and the
products. Accordingly, ligands shielded along the
HETPHEN concept (2 and 4) bind strongly to the copper
ions but are instructed not to undergo self-association to
homoleptic complexes. In combination with unshielded li-
gands 1 and 3 racks R1–R6 are formed in a stepwise man-
ner. Racks R1–R6 are dynamic in nature as demonstrated
in exchange processes at room temperature. Since CuI-based
bisphenanthroline complexes are potential photoactive de-
vices,[17] the present results should open an easy venue to
diverse functional aggregates. Studies are in progress to in-
stall multi-functionalities into these rack motifs and to
study their properties as a function of the dynamic behav-
iour.
(KBr): ν = 3411, 3057, 2919, 2209 (νCϵC), 1718, 1655, 1636, 1509,
˜
1438, 1381, 1083, 856, 729, 550. ESI-MS: calcd. for
2+
C96H76Br2Cu2N8
[M2+]: m/z 814.3, found: m/z 814.5.
C96H76Br2Cu2N8×2PF6×2H2O (1954.54): C 58.99, H 4.13, N 5.73;
found: C 58.95, H 4.01, N 5.84.
[Cu2(2)(3b)2](PF6)2 (R2): M.p. Ͼ 300 °C. 1H NMR (CD2Cl2,
200 MHz): δ = 8.78 (s, 2 H, phen), 8.74 (d, 2 H, J = 8.4 Hz, phen),
8.20–8.36 (m, 10 H, phen), 7.91 (d, 2 H, J = 7.9 Hz, phen), 7.53 (s,
2 H, phen), 6.84 (s, 4 H, phenyl), 6.15 (s, 4 H, mes), 2.91–3.01 (m,
8 H, hexyl), 1.83 (s, 12 H, benzyl), 1.56 –1.65(m, 30 H, benzyl),
1.33 (s, 32 H, aliph.), 0.86 (s, 12 H, aliph.). 13C NMR (CD2Cl2,
100 MHz): δ = 161.0, 159.9, 149.2, 144.1, 142.7, 142.3, 142.1, 140.5,
139.7, 138.6, 138.4, 138.1, 138.0, 137.7, 134.9, 133.4, 132.3, 131.8,
129.9, 129.1, 128.8, 128.1, 127.6, 127.3, 126.8, 124.4, 122.8, 122.5
(arom.); 96.7, 87.5 (ethynyl); 32.1, 31.8, 30.0, 29.4, 22.9, 20.6, 20.3,
Experimental Section
Ligands, 1a,[11] 1b,[11] 2,[11] 3b,[13] 4a,[6c] 4b[12] and 4c[13] were pre-
pared according to known procedures. 1H NMR and 13C NMR
were measured on a Bruker AC 200 (200 MHz) or Bruker AC 400
(400 MHz). All 1H NMR measurements were carried at room tem-
perature in [D2]dichloromethane. ESI-MS spectra were measured
on a LCQ Deca Thermo Quest. Typically, each time 25 scans were
accumulated for one spectrum. UV/Vis spectra were recorded on a
Tidas II spectrophotometer using dichloromethane as the solvent.
20.1, 18.4, 14.2 (aliph.). IR (KBr): ν = 3439, 2926, 2857, 2212
˜
(νCϵC), 1617, 1571, 1492, 1459, 1421, 1371, 1084, 842, 727, 635,
558. ESI-MS: calcd. for C120H120Br2Cl2Cu2N82+ [M2+]: m/z 1051.5,
found: m/z 1052.3. C120H124Br2Cl4Cu2N8O2×2PF6×2H2O
(2428.96): C 59.34, H 5.15, N 4.61; found: C 59.13, H 4.95, N 4.51.
[Cu2(1a)(4a)2](PF6)2 (R3): M.p. Ͼ 300 °C. 1H NMR (CD2Cl2,
200 MHz): δ = 8.51 (d, J = 8.6 Hz, 4 H, phen), 8.43 (m, 8 H, phen),
7.99 (s, 4 H, phen), 7.91 (m, 8 H, phen), 7.75 (dd, J = 8.9, J =
4.9 Hz, 2 H, phen), 7.06 (s, 2 H, phenyl), 4.01 (t, J = 5.5 Hz, 4 H, -
OCH2-), 1.70 (m, 40 H, benzyl), 1.53 (s, 14 H, benzyl and aliph.),
1.17–1.22 (m, 34 H, aliph.), 0.86 (t, J = 5.5 Hz, 6 H, aliph.). 13C
NMR (CD2Cl2, 100 MHz): δ = 160.1, 154.2, 149.3, 148.6, 145.1,
143.3, 142.1, 141.7, 138.9, 138.4, 136.3, 134.1, 133.6, 133.1, 130.4,
129.7, 129.1, 127.5, 126.8, 126.4, 123.4, 123.1, 118.5, 113.1 (arom.);
93.5, 91.4 (ethynyl); 33.4, 29.7 (2C), 30.1 (2C), 30.9 (2C), 26.5, 23.4,
Spectrophotometric titrations: Equilibrium constants of the com-
plexes were determined in dichloromethane. Ligands 2 and 3a were
titrated with aliquot amounts of a stock solution of copper(i) tetra-
kisacetonitrile hexafluorophosphate. All stock solutions were pre-
pared by careful weighing (microgram scale) on an analytical bal-
ance. Absorption spectra were recorded at 25.0 (0.1) °C. Since the
formation is instantaneous as evidenced by proton NMR, ESI-MS
analysis and visible colour changes, the solutions were immediately
analysed spectroscopically to avoid problems with the volatile sol-
21.1 (2C), 20.4, 19.1 (2C), 14.5 (aliph.). IR (KBr): ν = 3444, 2852,
˜
2208 (νCϵC), 1618, 1579, 1498, 1459, 1426, 1388, 1221, 1164,
Eur. J. Inorg. Chem. 2005, 1841–1849
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1847

V. Kalsani, H. Bodenstedt, D. Fenske, M. Schmittel
FULL PAPER
1018, 936, 872, 843, 724, 632, 558. ESI-MS: calcd. for
C122H126Br4Cu2N8O2
(arom.); 91.9, 84.5 (ethynyl); 32.4, 32.3 (2C), 31.1 (2C), 30.1 (2C),
29.2 (2C), 26.5, 23.1 (2C), 22.3 (2C), 14.5, 14.3, 13.8 (2C) (aliph.).
[M2+]: m/z 1091.5, found: m/z 1090.7.
2+
C122H128Br4Cu2N8O3×2PF6×H2O (2491.01): C 58.82, H 5.18, N IR (KBr): ν = 3461, 3053, 2923, 2853, 2209 (νCϵC), 1622, 1604,
˜
4.50; found: C 58.62, H 5.29, N 4.34.
1545, 1498, 1461, 1366, 1345, 1276, 1220, 1106, 1014, 958, 841,
2+
791, 736, 723, 557, 532. ESI-MS: calcd. for C162H158Cl4Cu2N8O2
[Cu2(1a)(4b)2](PF6)2 (R4): M.p. Ͼ 300 °C. 1H NMR (CD2Cl2,
200 MHz): δ = 8.62 (s, 2 H, phen), 8.58 (s, 4 H, phen), 8.39–8.8.51
(m, 6 H, phen), 8.15 (s, 4 H, phen), 7.18–7.96 (m, 8 H, phen), 7.70
(dd, J = 8.9, J = 4.1 Hz, 2 H, phen), 7.01 (s, 2 H, phenyl), 6.45 (t,
4 H, J = 8.4 Hz, phenyl), 5.71 (m, 8 H, phenyl), 3.95 (t, J = 6.7 Hz,
4 H, -OCH2-), 3.30 (s, 12 H, methoxy), 3.26 (s, 12 H, methoxy),
1.70–1.77 (m, 4 H, aliph.), 1.15–140 (m, 36 H, aliph.), 0.86 (t, J =
5.9 Hz, 6 H, aliph.). 13C NMR (CD2Cl2, 100 MHz): δ = 160.4,
159.3, 148.6, 143.5, 141.7, 141.5, 139.9, 139.2, 138.1, 137.9, 137.4,
137.1, 134.3, 132.8, 131.7, 131.2, 128.5, 128.2, 127.5, 127.0, 126.2,
123.8, 122.2, 121.9 (arom.); 96.1, 86.9 (ethynyl); 31.5, 31.3, 29.6,
29.4, 28. 8, 22.3, 20.1, 19.7, 19.6, 18.2, 18.0, 17.9, 13.6 (aliph.). IR
[M2+]:
m/z
1258.9,
found:
m/z
1257.9.
C162H164Cl4Cu2N8O5×2PF6×3H2O (2861.92): C 67.99, H 5.78, N
3.92; found: C 67.54, H 5.32, N 3.85.
[Cu2(1b)(4a)2](PF6)2 (R6): M.p. Ͼ 300 °C. 1H NMR (CD2Cl2,
400 MHz): δ = 8.75 (d, J = 8.08, 4 H, phen), 8.43–8.52 (m, 8 H,
phen), 8.25 (s, 4 H, phen), 7.91 (m, 8 H, phen), 7.75 (q, J = 4.8 Hz,
2 H, phen), 7.08 (s, 2 H, phenyl), 4.02 (t, J = 6.3 Hz, 4 H, -OCH2-
), 2.40 (s, 3 H, benzyl), 1. 95 (s, 3 H, benzyl), 1.77 (s, 16 H, aliph.),
1.65 (s, 12 H, benzyl), 1.53 (s, 12 H, benzyl), 1.45 (s, 6 H, benzyl),
1.41 (m, 6 H, benzyl), 1.20 (m, 6 H, benzyl), 0.71 (t, J = 7.08 Hz,
6 H, aliph.). 13C NMR (CD2Cl2, 100 MHz): δ = 159.1, 154.3, 149.0,
148.1, 144.6, 142.4, 141.2, 140.7, 138.7, 138.1, 135.2, 134.6, 133.1,
132.9, 132.5, 129.7, 128.8, 128.1, 127.1, 126.4, 125.2, 121.5, 116.1,
113.2 (arom.); 92.4, 91.1 (ethynyl); 31.2, 29.4, 25.4, 22.1, 21.6, 20.9,
(KBr): ν = 3443, 2924, 2851, 2208 (νCϵC), 1589, 1499, 1433, 1253,
˜
1222, 1112, 1023, 841, 777, 723, 558. ESI-MS: calcd. for
2+
C114H114N8O10Cu2
[M2+]: m/z 941.5, found: m/z 941.2.
C114H118Cu2N8O12×2PF6×2H2O (2209.22): C 61.98, H 5.38, N
19.6, 14.1 (aliph.). IR (KBr): ν = 3394, 2921, 2301 (νCϵC), 1736,
˜
5.07; found: C 61.85, H 4.35, N 5.04.
1618, 1495, 1427, 1426, 1368, 1018, 956, 842, 724, 633, 557. ESI-
MS: calcd. for C110H102Br4Cu2N8O2 [M2+]: m/z 1007.3, found:
2+
[Cu2(1a)(4c)2](PF6)2 (R5): M.p. Ͼ 300 °C. 1H NMR (CD2Cl2,
200 MHz): δ = 8.80 (s, 4 H, phen), 7.93 (s, 2 H, phen), 7.83 (d, 2
H, J = 7.9 Hz, phen), 7.61 (dd, J = 8.8, J = 4.1 Hz, 4 H, phen),
6.85–7.22 (m, 40 H, phen and anthracene), 6.64 (m, 4 H, phen and
phenyl), 4.19 (t, J = 6.4 Hz, 8 H, -OCH2-), 2.78 (m, 8 H, aliph.
and benzyl), 1.24–1.63 (m, 50 H, benzyl), 0.76–0.93 (m, 24 H, al-
iph.), 0.49 (t, J = 5.9 Hz, 12 H, aliph.). 13C NMR (CD2Cl2,
100 MHz): δ = 158.4, 158.4, 154.5, 155.2, 149.1, 147.3, 143.7, 143.1,
141.6, 140.9, 140.4, 139.6, 138.4, 136.6, 135.1, 133.5, 130.4, 129.4,
128.3, 127.4, 126.8, 125.9, 125.3, 124.9, 121.3, 117.5, 114.3, 103.9
m/z 1006.2; X-ray structure see Figure 4.
Crystal Structure Determinations: Crystals were obtained by slow
diffusion of toluene into a solution of the complexes in dichloro-
methane. Due to the poor quality of the crystals the crystal data
are not excellent. Solvent molecules are severely disordered. The
measurements were carried out with a STOE-IPDS2 diffractometer
with graphite-monochromatised Mo-Kα radiation. Table 3 summa-
rises the crystal data, data collection, and refinement parameters.
All calculations were performed with the SHELXS-97 package.
Table 3. X-ray experimental data for [Cu2(2)(MeCN)2×2PF6] and [Cu2(1b)(4a)×2PF6].
Formula
[Cu2(2)(MeCN)2×2PF6]
C76H66Br2Cu2F12N6P2
[Cu2(1b)(4a)2×2PF6]
C110H102Br4Cu2F12N8O2P2
Mw
1640.21
monoclinic
P1 21/c 1 (no. 14)
21.297(4)
2304.68
triclinic
P–1 (no. 2)
13.0625(80)
Crystal system
Space group
a [A°]
b [A°]
c [A°]
22.658(5)
17.044(3)
21.250(15)
23.75(2)
α [°]
β [°]
90.00
104.29(3)
113.00(3)
95.00(3)
γ [°]
90.00
7970(3)
94.00(3)
6006.46(800)
V [A3]
Z
Color
4
2
red
yellow
Crystal shape
Crystal dimensions
Dcalcd. [gcm–3]
F(000)
needle
0.3×0.15×0.1
1.367
3656
needle
0.3×0.15×0.1
1.274
2656
Radiation
Mo-Kα, graphite-monochromated
Mo-Kα, graphite-monochromated
Device type
Reflections collected
R(int.)
Independent reflections
Data/parameters
GOF on F2
Rreflections threshold expression
hkl limits (max./min.)
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
IPDS2 STOE
44882
0.0543
20487
20487/900
1.564
Ͼ2σ(I)
–23/29, –26/31, –23/21
R1 = 0.0919, wR2 = 0.2404
R1 = 0.1259, wR2 = 0.2558
IPDS2 STOE
43551
0.1144
22023
22023/1285
1.234
Ͼ2σ(I)
–16/16, –26/26, –29/29
R1 = 0.1281, wR2 = 0.2960
R1 = 0.2317, wR2 = 0.3352
1848
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1841–1849

Supramolecular Copper Phenanthroline Racks
FULL PAPER
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We would like to express our gratitude to the Deutsche Forschungs-
gemeinschaft (Schm 647/12-1 and -/13-1) and the Fonds der Chem-
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Received: October 25, 2004
Eur. J. Inorg. Chem. 2005, 1841–1849
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1849