Synthesis and binding properties of dendritic oxybathophenanthroline ligands towards copper(II)

Article abstract of DOI:10.1002/ejic.200500176

Dendritic oxybathophenanthroline ligands (generation 0 to 3) have been synthesized by treatment of 4,7-bis(4′-hydroxyphenyl)-1,10-phenanthroline with the corresponding Frechet-type dendrons carrying a benzylic bromide function at the focal point. The comp

Full text of DOI:10.1002/ejic.200500176

FULL PAPER
Synthesis and Binding Properties of Dendritic Oxybathophenanthroline
Ligands towards Copper(II
)
Holger Stephan,*[a] Gerhard Geipel,[b] Gert Bernhard,[b] Peter Comba,[c]
Gopalan Rajaraman,[c] Uwe Hahn,[d] and Fritz Vögtle*[d]
Keywords: Dendrimers / Phenanthroline / Copper() / Solvent extraction / Laser fluorescence spectroscopy
Dendritic oxybathophenanthroline ligands (generation 0 to
3) have been synthesized by treatment of 4,7-bis(4Ј-hy-
droxyphenyl)-1,10-phenanthroline with the corresponding
Fréchet-type dendrons carrying a benzylic bromide function
at the focal point. The complexation of copper(II) has been
studied by liquid–liquid extraction using the radioisotope
64Cu and time-resolved laser-induced fluorescence spec-
troscopy (TRLFS) in organic media indicating the formation
of 1:3 complexes (Cu:dendritic ligand). Electronic and EPR
spectroscopy were used to characterize the copper(II) chro-
mophore, which is shown to have the expected distorted
square-planar geometry with two phenanthroline donors co-
ordinated to the copper(II) center. The third dendritic ligand
therefore is proposed to be bound by secondary interactions.
The stability constants of the 1:3 complexes were found to be
in the order of log K Ϸ 16 in CHCl3. On the other hand, in-
creasing generation of the dendritic Fréchet-type branches
leads to enhanced shielding of the copper ion from the envi-
ronment. Additional information about this behaviour was
obtained by the fluorescence lifetimes, which are much less
influenced upon addition of copper(II) salt to solutions of the
higher generation ligands.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
(complex stability, kinetics of formation) in manifold direc-
tions.[5] Due to steric reasons, the attachment of highly
branched units particularly in the 4,7- and 3,8-positions of
the 1,10-phenanthroline core seems to be suited in this re-
spect (Scheme 1). In addition Fréchet-type dendrons being
attached adjacent to the metal coordination centre (2,9-po-
sitions) have also been presented.[6]
Introduction
Derivatives of 1,10-phenanthroline and their metal com-
plexes are of considerable interest in bioinorganic chemis-
try, biology and medicine.[1] Oxidative substitutions of 1,10-
phenanthroline give versatile 5,6-disubstituted intermedi-
ates for the introduction of less bulky groups into the che-
lating unit. Such 5,6-substituted phenanthrolines play an
important role as hydrophobic DNA intercalators (dipyri-
dophenazine[2]), and most representatives of chromophore-
containing derivatives base on this substitution pattern.[3]
Also, metallodendrimers consisting of ruthenium() com-
plexes with bisphenanthroline ligands bridged in the 5,6-
positions have been described as robust, structurally rigid
and well-defined nanoscopic complexes.[4] Dendritic modifi-
cations gain in importance as they open the way for tailor-
ing nano dimension, solubility or complexation behaviour
[a] Institut für Bioanorganische und Radiopharmazeutische
Chemie, Forschungszentrum Rossendorf,
Postfach 510119, 01314 Dresden, Germany
Fax: +49-351-260-3232
E-mail: h.Stephan@fz-rossendorf.de
[b] Institut für Radiochemie, Forschungszentrum Rossendorf,
Postfach 510119, 01314 Dresden, Germany
[c] Anorganisch-Chemisches Institut, Universität Heidelberg,
Im Neuenheimer Feld 270, 69120 Heidelberg
[d] Kekulé-Institut für Organische Chemie und Biochemie, Uni-
versität Bonn,
Scheme 1. Suitable positions for dendritic modification of 1,10-
phenanthroline.
Gerhard-Domagk-Str. 1, 53121 Bonn, Germany
Fax: +49-228-73-3495
E-mail: voegtle@uni-bonn.de
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Ruthenium() complexes containing 4,7-bis(benzyloxy)-
1,10-phenanthroline units[7] and also dendritic rutheni-
Eur. J. Inorg. Chem. 2005, 4501–4508
DOI: 10.1002/ejic.200500176
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H. Stephan, G. Geipel, G. Bernhard, P. Comba, G. Rajaraman, U. Hahn, F. Vögtle
FULL PAPER
um() complexes bearing bis-substituted 2,2Ј-bipyridine sized in a multi-step sequence (Scheme 3).[11] The β-chloro
moieties have been reported to exhibit interesting lumines- ketone 3 was prepared by a Friedel–Crafts acylation of 3-
cence and redox properties.[8] Ruthenium() dendrimers chloropropionyl chloride (2) and anisole (1) in dry 1,2-
containing carbazole-based chromophores as branches in dichloroethane at 0 °C in the presence of anhydrous alumi-
the 4,7-positions of phenanthroline exhibit significant ab- num chloride to yield a colourless solid. The reaction of the
sorption and luminescence characteristics.[9] Complexation β-chloro ketone 3 with o-nitroaniline (4) under the condi-
of appropriate metals with phenanthroline ligands carrying tions of the Yale modification of the Skraup quinoline syn-
branched units in the 3,8-positions induces the formation of thesis, gave the 4-substituted 8-nitroquinoline 5 as a yellow
supramolecular self-assemblies with tuneable coordination solid. The nitro group was subsequently reduced with tin()
geometry.[10] In this respect, we are interested to character- chloride dihydrate in dry ethanol under reflux conditions
ize the self-assembly system involving novel dendritic com- to form the 4-(4Ј-methoxyphenyl)-8-aminoquinoline 6 as a
pounds and copper(). Here, we report the synthesis of yellow solid. The 4,7-disubstituted 1,10-phenanthroline 7
1,10-phenanthroline ligands
L
G0–LG3 with attached was obtained by a second Skraup reaction of aminoquino-
Fréchet-type dendrons (generation 0 to 3) in the 4,7-posi- line 6 and β-chloro ketone 3 using again the conditions of
tions (Scheme 2). The complexation behaviour of these the Yale modification. Demethylation of the bisanisyl-1,10-
hydrophobic dendritic oxybathophenanthroline derivatives phenanthroline (7) was performed in dry dichloromethane
towards CuII has been studied by liquid-liquid extraction at –20 °C by treatment with boron tribromide to yield the
experiments, time-resolved laser-induced fluorescence spec- phenanthroline building block 8 carrying two hydroxy func-
troscopy and electronic as well as EPR spectroscopy.
tions to which the various dendritic wedges could be at-
tached.[12]
Scheme 3. Preparation of the 4,7-bis(p-hydroxyphenyl)-1,10-phen-
anthroline (8); (i) 0 °C, 3 h, 1,2-dichloroethane; (ii) addition of 3
at 100–120 °C, aq. As2O5 (80%), concd. H3PO4, 140 °C, 1 h, (iii)
SnCl2·2H2O, reflux, 4 h, EtOH, (iv) addition of BBr3 at –20 °C,
2 h, room temp., CH2Cl2.
The dendritic oxybathophenanthroline (OBP) ligands
L
G0–LG3 were synthesized according to Scheme 4. Thus,
1 equiv. of 4,7-bis(4Ј-hydroxyphenyl)-1,10-phenanthroline
(8) was dissolved in DMF and deprotonated by treatment
with sodium hydride. Addition of 2 equiv. of benzyl bro-
mide (9) or the corresponding dendritic benzyl bromides[13]
10–12 followed by purification on silica gel gave the prod-
ucts in medium to high yields as colourless solids in the case
of the benzyl derivative, or as viscous oils for the higher
Scheme 2. Constitutions of the investigated dendritic OBP ligands
L
G0–LG3
.
Results and Discussion
Syntheses
The parent phenanthroline ligand 8 with two p-hy- generations. The medium yield for the benzyl-substituted
droxyphenyl groups in the positions 4 and 7 was synthe- derivative LG0 may be explained by the formation of a N,O-
4502
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Eur. J. Inorg. Chem. 2005, 4501–4508

Dendritic Oxybathophenanthroline Ligands towards CoII
FULL PAPER
Scheme 4. Schematic representation for the preparation of the dendritic oxybathophenanthroline (OBP) ligands; (i) NaH (60% in paraf-
fin), room temp., 1 d, DMF.
dibenzyl derivative, in which one nitrogen of the phenan-
throline unit is substituted by a benzylic moiety.[14] Due to
the small size of benzyl bromide such a cyclohexa-2,5-dien-
one derivative can be formed in higher quantities. But for
the dendritic generations with an increased steric demand
this side reaction seems to be less favoured and leads there-
fore to higher yields. Additionally, the purification of LG0
on silica gel was more difficult as a result of the higher
polarity of the phenanthroline unit. Substitution of the
phenanthroline building block 8 with dendritic units of a
various size leads to an increased lipophilicity of the ligands
and thus to easier purification by column chromatography.
Figure 1. Extractability of copper() by dendritic OBP ligands
L
G0–LG3; black bars cCu(NO ) = 1×10–4 , cHPic = 5×10–3 , pH
The structures of all new oxybathophenanthroline ligands
2
= 5.3 (MES/NaOH); white 3bars cCu(NO ) = 1×10–4 , pH = 5.3
1
could be readily deduced from H and 13C NMR spectra
(MES/NaOH); cdendritic ligand = 1×10–3  i2n CHCl3, time = 30 min-
3
as well as from mass spectrometric analysis.
utes.
Interestingly, a rapid attainment of extraction equilib-
rium (within few minutes) was observed. Even in the case
of the most bulky ligand LG3 the equilibrium was attained
after 10 minutes.[17] As expected, the CuII extraction is en-
hanced with increasing pH accompanied by decreasing pro-
tonation of the chelating moiety.[18] Information about the
overall stoichiometry of the complexation was obtained by
measuring the distribution ratio DCu[19] as a function of the
ligand concentration in the organic solvent (Figure 2).
Liquid–Liquid Extraction
1,10-Phenanthroline is known to form strong complexes
with copper(). Depending on the experimental conditions,
the resulting complexes may have 1:1, 1:2 or 1:3 stoichiome-
try (metal/ligand), and show different coordination geome-
tries.[15] Due to the Jahn–Teller lability 1:3 stoichiometry
(pseudo-octahedral coordination geometry) is unlikely with
the rigid phenanthroline-type chelates. By virtue of the high
lipophilicity of the dendritic oxybathophenanthrolines, li-
quid–liquid extraction experiments have been chosen to
characterise the binding properties of the OBP ligands LG0
–
LG3 towards CuII in the aqueous-organic system Cu(NO3)2/
buffer/H2O/dendritic ligand/CHCl3. Precise data of the
efficiency of complex formation and the stoichiometry of
the copper() complexes with the ligands investigated were
obtained using the radiotracer technique with 64Cu as ra-
dioisotope.[16] First extraction experiments have been per-
formed in the presence of the lipophilic picrate anion (Fig-
ure 1). In this case the extractability of CuII is almost quan-
titative for all ligands. But also in the absence of the picrate
anion, CuII is very efficiently extracted into the organic
phase. Here, a dendritic effect is clearly visible caused most
likely by the increasing lipophilicity of the complexes
formed.
Figure 2. Variation of log DCu with ligand concentration for the
extraction of copper() with dendritic OBP ligands LG1–LG3
;
cCu(NO ) = 1×10–4 , pH = 5.3 (MES/NaOH), time = 30 minutes,
3
2
cdendritic ligand = 2×10–4  to 1×10–3  in CHCl3.
Eur. J. Inorg. Chem. 2005, 4501–4508
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H. Stephan, G. Geipel, G. Bernhard, P. Comba, G. Rajaraman, U. Hahn, F. Vögtle
FULL PAPER
Surprisingly, in all cases, the slopes of the lines in the log 430 nm component disappears. This behaviour is in agree-
DCu/logcligand plots were 3 if the ligand excess is high ment with the results of the liquid–liquid extraction (1:3
enough compared to the copper concentration. This finding complexes). The ligand LG2 shows a somewhat different be-
indicates the formation of 1:3 complexes (CuII: dendritic haviour. Here, the fluorescence disappears at a 1:2 ratio of
ligand).[20] However, this is not an indication for three phen- CuII to ligand. In a separate measurement with a metal to
anthroline donors, coordinated to the copper() centers (see ligand ratio of 1:3 only a monoexponential fluorescence de-
below).[21]
cay with the longer fluorescence lifetime was observed. This
is strong evidence that also a 1:3 adduct is formed.
In addition the fluorescence intensities were used to con-
firm complex formation. Due to the observation that
mainly the fluorescence intensity of the component with the
shorter fluorescence lifetime is influenced by the complex
formation these data were evaluated for the stability of the
complexes. The species concentration can be calculated
from the fluorescence intensities of the free ligand. The re-
sulting stability constants are summarized in Table 2.
Luminescence Characteristics
The fluorescence properties of the ligands LG0–LG3 are
summarized in Table 1. The time-resolved fluorescence
spectrum of LG0 is shown in Figure 3 as an example.
Table 2. Stability constants of the formed CuII complexes.
Ligand
Metal
Stoichiometry
log K
Solvent
LG0
LG1
LG2
LG3
CuII
CuII
CuII
CuII
3:1
3:1
3:1
3:1
16.4 0.8
17.5 0.9
15.6 0.7
16.6 0.7
CHCl3
CHCl3
CHCl3
CHCl3
It was found that the fluorescence decay times of the
longer decay component decrease with increasing size of the
dendritic branches if no copper() is added. The addition of
copper() influences the fluorescence lifetime (Supporting
Information, Table 2). However, this effect decreases with
increasing size of the dendritic wedge. The longer fluores-
cence lifetime as function of the cooper() concentration
shows no clear behaviour. For the ligand LG0 a clear dy-
namic quench effect was observed, which is much less re-
markable for the ligand LG1. The ligand LG2 shows an in-
crease of the fluorescence lifetime. For the ligand LG3 ad-
dition of copper() resulted in much less influence. How-
ever, also intermediate deviations from this trend were ob-
served. A profound explanation of this behaviour is not
possible at this time. The fluorescence lifetime of the second
component with the shorter lifetime is also influenced by
the addition of CuII. This behaviour can be explained by a
less pronounced dynamic quenching effect of the CuII or
in reverse, that the increasing generation of the dendritic
structure leads to an increased shielding effect on the deex-
citation channels of the copper().
Figure 3. Time-resolved fluorescence spectrum of the dendritic
OBP ligand LG0, cdendritic ligand = 1×10–5  in CHCl3.
For all four ligands a two-exponential fluorescence decay
behaviour was observed in the absence of CuII. The compo-
nent with the shorter fluorescence decay time shows the
higher fluorescence intensity. The maximum of this fluores-
cence emission is located at ca. 430 nm. The fluorescence
maximum for the second emitting component was found at
ca. 420 nm. Additionally the fluorescence decay time of this
component depends on the size of the dendritic wedges.
Going to higher generations the fluorescence decay times
decrease. This may be due to an increasing number of deac-
tivation channels.
Addition of copper() to the solution of the ligands leads
to a decrease in fluorescence intensity (static fluorescence
quenching). As expected, the complexes formed do not
show any fluorescence. The fluorescence with the shorter
fluorescence lifetime was mainly influenced by the forma-
tion of the complexes (see Table 1 in the Supporting Infor-
mation; for details see the footnote on the first page of this
Geometry of the Copper(II) Chromophores
Due to the Jahn–Teller lability of the d9 copper() ions
article). At CuII/ligand ratios of 1:3 the fluorescence of the the formation of stable [Cu(L)3]2+ complexes, where L is a
Table 1. Fluorescence properties of the dendritic OBP ligands.
Ligand
Center of gravity Fluorescence decay
Center of gravity
Fluorescence decay
Intensity ratio
(1)/(2)
Intensity relative
to L0
(1)
time (1)
ps
(2)
nm
time (2)
s
nm
LG0
LG1
LG2
LG3
430.1
430.3
431.8
430.1
160
270
240
260
2
2
2
2
423.7
417.0
419.9
417.2
1860 10
1080 10
990 10
890 10
22.6
3.3
3.6
3.3
1
1.45
1.57
1.05
4504
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Dendritic Oxybathophenanthroline Ligands towards CoII
FULL PAPER
bidentate ligand, is not likely, specifically with L = 1,10- ligand probably is bound by secondary interactions. The
phenanthroline derivatives. One would rather expect the dendritic ligands are capable to extract CuII with high effi-
stabilization of a distorted square planar (tetragonally dis- ciency. For extraction experiments a dendritic effect was
torted octahedral or square pyramidal) chromophore de- found most likely caused by the increasing lipophilicity
rived from [Cu(L)2(X)n]2+, where X may be OH2 and n = when going to higher generations. As obtained by titration
0, 1, 2. The third dendritic phenanthroline ligand found in experiments using TRLFS, the dendritic ligands LG0–LG3
the extraction and luminescence experiments may then be form strong 1:3 adducts with copper() in CHCl3 (log K Ϸ
bound by secondary interactions (outer sphere coordina- 16). Studies of the fluorescence lifetimes show an increased
tion) to the distorted square-planar complex. The type of shielding effect with increasing generation of the dendritic
chromophore was analyzed by electronic and EPR spec- wedge attached to the phenanthroline unit. The results ob-
troscopy and supported by molecular mechanics modeling. tained for the copper() complexation with hydrophobic
Solutions for the UV/Vis-NIR and EPR spectra (LG0 and dendritic phenanthroline ligands have encouraged us to de-
L
G3) were prepared as those for the liquid–liquid extrac- velop water-soluble analogues having targeting units at the
tions ([Cu(trif)2]2+, H2O/L, CHCl3; [Cu2+] Ϸ 1.0 m, periphery in view of binding and selective transport of the
[Cu2+]:[L] = 1:3). The electronic spectra (Supporting Infor- diagnostically and therapeutically relevant radioisotopes
mation) show two broad transitions centered at approx. 64Cu and 67Cu.
708 nm and 925 nm for LG0, and 734 nm and 925 nm for
L
G3, respectively. The lower energy band is due to the dz2
– y2
Ǟ dx2
transition and was not well resolved in our spectra
Experimental Section
(relatively low concentration), the feature at higher energy
is due to transitions from dxy, dxz, dyz and therefore is, as
expected, very broad. While [Cu(phen)3]2+ (phen = 1,10-
phenanthroline) was reported to have transitions at 680 nm
and 1250 nm,[22] [Cu(phen)2(OH2)n]2+ (n = 0, 1, 2) has tran-
sitions at 750–800 nm and ca. 980 nm.[22,23] Addition of up
to 3 equiv. of phen did not change the spectroscopic param-
eters. The assignment of these transitions to CuN4On (n =
0, 1, 2) chromophores is supported by EPR spectra (iden-
tical solutions, T = 100 K). The analysis of the spin Hamil-
tonian parameters (gx = 2.06, gy = 2.08, gz = 2.22, Ax = Ay
= 45 G, Az = 128 G) supports this conclusion (experimental
and simulated spectra are given in the Supporting Infor-
mation): the major features are similar to those reported for
General Remarks: All starting materials were purchased from com-
mercial sources and used without further purification. The den-
dritic bromides[13] 9–12 and the 4,7-(bisanisyl)phenanthroline[11] (7)
have been prepared according to literature. The solvents were dried
using standard techniques. Reactions were monitored by thin-layer
chromatography using TLC plates pre-coated with silica gel 60F254
(Merck) and compounds detected by UV light (254 nm). Column
chromatography was carried out using silica gel (Merck 15101).
Melting points were determined with a Reichert Thermovar micro-
scope and were not corrected. H and 13C NMR spectra were re-
1
corded using Avance 300 and AM 400 MHz Bruker instruments;
the solvent signal was used for internal calibration. Mass spectra
were recorded using a MS-50 from A.E.I., Manchester, GB (EI), a
Concept 1H from Kratos Analytical Ltd., Manchester, GB (FAB),
or a MALDI-TofSpec-E from MICROMASS, GB (MALDI). Elec-
tronic spectra were recorded with a JASCOV-570 UV/Vis-NIR
spectrophotometer and EPR spectra were obtained from a Bruker
ELEXSYS-E-500 instrument (X-band); spin-Hamiltonian param-
eters were obtained by simulation of the spectra with XSophe (ver-
sion 1.1.4).[29]
the EPR spectra of distorted square planar [Cu(phen)2]2+
-
type chromophores,[24] the minor features are similar to
those of [Cu(phen)2(OH2)](NO3)2 (gx = 2.02, gy = 2.13, gz
= 2.23).[25]
The conclusion that the extracted copper() species are
[Cu(L)2(OH2)n]2+·L is supported by strain energy mini-
mized structures, using the MOMEC program[26] and force
field[27] (for structural data and plots of the optimized struc-
tures see Supporting Information). The optimized struc-
tures ([Cu(L)2(OH2)2]2+) have Cu–N distances (ca. 1.97 Å)
and tetrahedral distortions of the CuN4 chromophores (ca.
42°) which are very similar to those of reported [Cu-
(phen)2(OH2)n]2+-type structures.[28]
3-Chloro-1-(4Ј-methoxyphenyl)propan-1-one (3): To a suspension of
powdered aluminum chloride (7.23 g, 54.2 mmol) in dry 1,2-dichlo-
roethane (40 mL) were added slowly 3-chloropropionyl chloride (2)
(4.55 mL, 47.4 mmol) at 0 °C and anisole (1) (4.91 mL, 45.2 mmol)
under cooling with water. The orange solution was stirred at room
temp. for 3 h and left standing for about 12 h. The dark orange
solution was poured onto ice (50 g), the organic phase separated
and the aqueous phase extracted two times with CH2Cl2. The col-
lected organic phases were washed with water, several times with
aqueous NaOH (2%, 50 mL) until the organic phase did not turn
back to yellow, and then twice with water. The organic phase was
dried with MgSO4 and the solvent removed under reduced pressure.
Purification by gradient column chromatography [SiO2, CH2Cl2/
petroleum ether (40/60), 20:1 to CH2Cl2] gave 9.23 g (97% yield)
of a colourless solid. Rf = 0.68 (CH2Cl2); m.p. 63–64 °C. 1H NMR
(300 MHz, CDCl3, 25 °C): δ = 3.29 (t, J = 7 Hz, 2 H, CH2Cl), 3.75
(s, 3 H, OCH3), 3.80 (t, J = 7 Hz, 2 H, COCH2), 6.82 (AAЈ part
of the AAЈBBЈ system, 2 H, Har), 7.82 (BBЈ part of the AAЈBBЈ
system, 2 H, Har) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ =
39.0, 40.9, 55.5, 113.9, 129.6, 130.4, 163.9, 195.2 ppm. MS (EI,
Conclusions
An efficient synthetic strategy has been developed for the
preparation of new dendritic ligands consisting of a 1,10-
phenanthroline core unit to which hydrophobic polybenzyl
ether dendrons are attached in the 4,7-positions. These oxy-
bathophenanthroline ligands rapidly form very stable 1:3
adducts in organic media with CuII. Electronic and EPR
spectroscopy suggest that two of the ligands are coordi-
nated to copper() by the phenanthroline donors, the third 70 eV): m/z (%) = 198 (12) [M+·].
Eur. J. Inorg. Chem. 2005, 4501–4508
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H. Stephan, G. Geipel, G. Bernhard, P. Comba, G. Rajaraman, U. Hahn, F. Vögtle
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4-(4Ј-Methoxyphenyl)-8-nitroquinoline (5): To a solution of o-nitro-
phase was dried with MgSO4 and the solvent removed under re-
aniline (4) (1.38 g, 10.0 mmol), aq. As2O5 (3.37 g, 80%) and concd. duced pressure. The remaining solid was three times suspended in
H3PO4 (9 mL) was added portionwise β-chloro ketone 3 (2.48 g,
12.5 mmol) at 100 °C in 10 min so that the temperature is not rising
above 120 °C. The solution was stirred at 120 °C for 5 min and
then heated to 140 °C for 1 h. The deep red solution was cooled to
room temp., poured onto CH2Cl2 (150 mL) and water (100 mL),
and neutralized with aq. KOH (30%). The aqueous phase was ex-
tracted several times with CH2Cl2, the collected organic phase
dried with MgSO4, and the solvent removed under reduced pres-
sure. Column chromatography (SiO2, CH2Cl2) gave 1.56 g (56%)
of a yellow coloured solid. Rf = 0.40 (CH2Cl2); m.p. 134–135 °C.
1H NMR (400 MHz, CDCl3, 25 °C): δ = 3.95 (s, 3 H, CH3), 7.09
(AAЈ part of the AAЈBBЈ system, 2 H, Har), 7.41 (BBЈ part of the
AAЈBBЈ system, 2 H, Har), 7.43 (d, J = 4 Hz, 1 H, Har), 7.55 (dd,
J = 9, J = 8 Hz, 1 H, Har), 7.98 (dd, J = 8, J = 1 Hz, 1 H, Har),
8.17 (dd, J = 9, J = 1 Hz, 1 H, Har), 9.02 (d, J = 4 Hz, 1 H, H)
ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ = 55.6, 114.5, 122.9,
123.4, 125.1, 128.1, 129.2, 130.2, 131.0, 140.2, 148.7, 149.0, 152.1,
160.5 ppm. MS (EI, 70 eV): m/z (%) = 280 (100) [M+·].
CH2Cl2 and filtered. The solid was dried to yield a yellow solid
(3.20 g, 47%). M.p. 285–288 °C. H NMR (400 MHz, [D6]DMSO,
1
25 °C): δ = 6.98 (AAЈ part of the AAЈBBЈ system, 4 H, Har), 7.41
(BBЈ part of the AAЈBBЈ system, 4 H, Har), 7.65 (d, J = 5 Hz, 2
H, Har), 7.92 (s, 2 H, Har), 9.08 (d, J = 5 Hz, 2 H, Har) ppm. 13C
NMR (100 MHz, [D6]DMSO, 25 °C): δ = 116.1, 124.0, 124.3,
126.3, 128.0, 131.5, 145.9, 148.7, 149.5, 158.6 ppm. MS (EI, 70eV):
m/z (%) = 392 (100) [M+·].
General Procedure for the Preparation of Dendritic OBP Ligands
(LG0–LG3): To a suspension of 4,7-bis(4Ј-hydroxyphenyl)-1,10-
phenanthroline (8) (0.1 mmol) in dry DMF (10 mL) was added
NaH (0.22 mmol, 60% in paraffin). The reaction mixture turned
to red. After 5 min a solution of the corresponding bromides[13] 9–
12 (0.21 mmol) in dry DMF (5 mL) was added, and the suspension
stirred for 1 d at room temp. The residual NaH was deactivated by
slow addition of water at 0 °C. CH2Cl2 (30 mL) was added, the
suspension neutralized with aq. HCl (2 ), and the aqueous phase
extracted several times with CH2Cl2. The collected organic phase
was washed with concd. aq. NaHCO3, water, dried with MgSO4
and the solvent removed under reduced pressure. The crude prod-
uct was purified by column chromatography on silica gel.
8-Amino-4-(4Ј-methoxyphenyl)quinoline (6): A solution of nitro-
chinoline 5 (1.15 g, 4.1 mmol) and tin() chloride dihydrate (2.78 g,
12.3 mmol) in dry ethanol (30 mL) was refluxed for 4 h. The solu-
tion was cooled to room temp. and made alkaline with concd. etha-
nolic NaOH. The precipitate was filtered off, and the solvent re-
moved under reduced pressure. Purification by gradient column
chromatography (SiO2, CH2Cl2 to CH2Cl2/methanol, 30:1) gave
0.91 g (89%) of a yellow solid. Rf = 0.18 (CH2Cl2); m.p. 148–
149 °C. 1H NMR (400 MHz, CDCl3, 25 °C): δ = 3.78 (s, 3 H, CH3),
4.95 (br. s, 2 H, NH2), 6.81 (dd, J = 6, J = 3 Hz, 1 H, Har), 6.93
(AAЈ part of the AAЈBBЈ system, 2 H, Har), 7.16 (m, 3 H, Har),
7.24 (BBЈ part of the AAЈBBЈ system, 2 H, Har), 8.62 (d, J = 4 Hz,
1 H, Har) ppm. 13C NMR (100 MHz, CDCl3, 25 °C): δ = 55.4,
109.9, 114.0, 114.2, 121.7, 127.2, 127.6, 130.8, 131.0, 138.9, 144.3,
147.0, 148.1, 159.8 ppm. MS (EI, 70 eV): m/z (%) = 250 (100) [M+·].
4,7-Bis(4Ј-benzyloxyphenyl)-1,10-phenanthroline (LG0): 4,7-Bis(4Ј-
hydroxyphenyl)-1,10-phenanthroline (8) (100.0 mg, 0.27 mmol),
benzyl bromide 9 (98.6 mg, 0.58 mmol), NaH (24.2 mg, 0.60 mmol,
60% in paraffin) in dry DMF (15 mL). Column chromatography
(SiO2, CH2Cl2/MeOH, 50:1 to 20:1) gave a colourless solid
(69.8 mg, 47%). Rf = 0.42 (CH2Cl2/MeOH, 5:1); m.p. 230–231 °C.
1H NMR (400 MHz, CDCl3): δ = 5.12 (s, 4 H, OCH2), 7.10 (AAЈ
part of the AAЈBBЈ system, 4 H, Har), 7.30–7.47 (m, 14 H, Har),
7.52 (d, J = 5 Hz, 2 H, Har), 7.85 (s, 2 H, Har), 9.16 (d, J = 5 Hz,
2 H, Har) ppm. 13C NMR (100 MHz, CDCl3): δ = 70.2, 115.1,
123.5, 124.0, 126.5, 127.5, 128.1, 128.7, 130.6, 131.0, 136.7, 147.0,
148.1, 149.7, 159.2 ppm. MS (FAB, NBA): m/z (%) = 545.2 ([M +
H]+, 100), 454.1 (12), 307.0 (18).
4,7-Bis(4Ј-methoxyphenyl)-1,10-phenanthroline (7): To a solution of
the aminoquinoline 6 (1.43 g, 5.7 mmol), aq. As2O5 (1.61, 80%)
and concd. H3PO4 (9 mL) was added portionwise the β-chloro
ketone 3 (1.58 g, 7.1 mmol) at 100 °C in 10 min so that the tem-
perature is not rising above 120 °C. The solution was stirred at
120 °C for 5 min and then heated to 140 °C for 1 h. The deep red
reaction mixture was cooled to room temp., poured onto CH2Cl2
(150 mL) and water (100 mL) and neutralized with aqueous NaOH
(20%). The aqueous phase was extracted several times with
CH2Cl2, the collected organic phase dried with MgSO4 and the
solvent removed under reduced pressure. Column chromatography
(SiO2, CH2Cl2) yielded a brownish solid (1.50 g, 67%). Rf = 0.35
(CH2Cl2/MeOH, 5:1); m.p. 208–209 °C. 1H NMR (400 MHz, 1:1
CDCl3/CD3OD, 25 °C): δ = 2.41 (s, 6 H, CH3), 5.58 (AAЈ part of
the AAЈBBЈ system, 4 H, Har), 5.95 (BBЈ part of the AAЈBBЈ sys-
tem, 4 H, Har), 6.10 (d, J = 5 Hz, 2 H, Har), 6.40 (s, 2 H, Har), 7.62
(d, J = 5 Hz, 2 H, Har) ppm. 13C NMR (100 MHz, CDCl3, 25 °C):
δ = 54.9, 114.0 123.6, 123.9, 126.5, 129.7, 130.8, 146.2, 148.6, 149.1,
160.1 ppm. MS (EI, 70 eV): m/z (%) = 392 (100) [M+·].
4,7-Bis{4Ј-[3ЈЈ,5ЈЈ-bis(benzyloxy)benzyloxy]phenyl}-1,10-phen-
anthroline (LG1): 4,7-Bis(4Ј-hydroxyphenyl)-1,10-phenanthroline (8)
(120.0 mg, 0.33 mmol), dendritic Fréchet-type G1 bromide 10
(256.1 mg, 0.69 mmol), NaH (29.0 mg, 0.73 mmol, 60% in paraf-
fin) in dry DMF (15 mL). Column chromatography (SiO2, CH2Cl2/
MeOH, 50:1 to 20:1) gave a brownish viscous oil (269.5 mg, 84%).
1
Rf = 0.55 (CH2Cl2/MeOH, 10:1). H NMR (400 MHz, CDCl3): δ
= 5.05 (s, 8 H, OCH2), 5.08 (s, 4 H, OCH2), 6.58 (t, J = 2 Hz, 2
H, Har), 6.72 (d, J = 2 Hz, 4 H, Har), 7.10 (AAЈ-part of the
AAЈBBЈ-system, 4 H, Har), 7.26–7.47 (m, 24 H, Har), 7.51 (d, J =
5 Hz, 2 H, Har), 7.90 (s, 2 H, Har), 9.18 (d, J = 5 Hz, 2 H, Har)
ppm. 13C NMR (100 MHz, CDCl3): δ = 70.1, 70.2, 101.7, 106.5,
115.1, 123.5, 124.0, 126.5, 127.6, 128.6, 130.6, 131.0, 136.8, 139.3,
147.0, 148.1, 149.7, 159.1, 160.3 ppm. MS (FAB, NBA): m/z (%) =
969.5 ([M + H]+, 60), 307.1 (100).
4,7-Bis(4Ј-{3ЈЈ,5ЈЈ-bis[3ЈЈЈ,5ЈЈЈ-bis(benzyloxy)benzyloxy]benzyl}-
phenyl)-1,10-phenanthroline (LG2): 4,7-Bis(4Ј-hydroxyphenyl)-1,10-
phenanthroline (8) (70.0 mg, 0.19 mmol), dendritic Fréchet-type
G2 bromide 11 (325.9 mg, 0.40 mmol), NaH (16.9 mg, 0.42 mmol,
60% in paraffin) in dry DMF (15 mL). Column chromatography
(SiO2, CH2Cl2/MeOH, 50:1 to 20:1) gave a brownish viscous oil
(246.0 mg, 70 %). Rf = 0.51 (CH2Cl2/MeOH, 10:1). 1H NMR
(400 MHz, CDCl3): δ = 4.86 (s, 8 H, OCH2), 4.89 (s, 16 H, OCH2),
4.96 (s, 4 H, OCH2), 6.58 (t, J = 2 Hz, 6 H, Har), 6.57 (d, J = 2 Hz,
8 H, Har), 6.59 (d, J = 2 Hz, 4 H, Har), 7.00 (AAЈ part of the
AAЈBBЈ system, 4 H, Har), 7.17–7.28 (m, 40 H, Har), 7.12 (BBЈ
4,7-Bis(4Ј-hydroxyphenyl)-1,10-phenanthroline (8): To a solution of
4,7-bis(4Ј-methoxyphenyl)-1,10-phenanthroline
(7)
(6.77 g,
17.3 mmol) in dry dichloromethane (90 mL) was added dropwise
boron tribromide (4.91 mL, 51.8 mmol) at –20 °C. The red suspen-
sion was stirred at room temp. for 2 h, poured onto ice and let
stand still for 30 min. The solution was neutralized with aq. KOH
(5%), the organic phase separated and the aqueous phase extracted
several times with 10:1 CH2Cl2/MeOH. The collected organic
4506
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 4501–4508

Dendritic Oxybathophenanthroline Ligands towards CoII
FULL PAPER
Diego, San Francisco, Singapore, Sydney, Tokyo, 2004, vol. 1,
25–39; b) A. von Zelewsky, Stereochemistry of Coordination
Compounds, Wiley, Chichester, New York, 1996.
part of the AAЈBBЈ system, 4 H, Har), 7.40 (d, J = 5 Hz, 2 H, Har),
7.88 (s, 2 H, Har), 9.08 (d, J = 5 Hz, 2 H, Har) ppm. 13C NMR
(100 MHz, CDCl3): δ = 70.0, 70.1, 70.2, 101.7, 101.7, 106.5, 106.6,
115.2, 123.6, 124.0, 126.5, 127.6, 128.1, 128.3, 128.6, 130.6, 131.1,
136.8, 136.9, 139.3, 139.4, 147.0, 148.1, 149.8, 159.1, 160.1, 160.2
ppm. MS (FAB, NBA): m/z (%) = 1818.6 ([M + H]+, 17), 303.1
(100).
[2]
[3]
a) M. Yamada, Y. Tanaka, Y. Yoshimoto, S. Kuroda, I. Shi-
mao, Bull. Chem. Soc. 1992, 65, 1006–1011; b) J.-C. Chambron,
J.-P. Sauvage, E. Amouyal, P. Koffi, New J. Chem. 1985, 9, 527–
529; c) E. Amouyal, A. Homsi, J.-C. Chambron, J.-P. Sauvage,
J. Chem. Soc., Dalton Trans. 1990, 1841–1845; d) Y. Jenkins,
J. K. Barton, J. Am. Chem. Soc. 1992, 114, 8736–8738; e) V. W.-
W. Yam, K. K.-W. Lo, K.-K. Cheung, R. Y.-C. Kong, J. Chem.
Soc., Chem. Commun. 1995, 1191–1193.
a) T. Mizuno, W.-H. Wie, L. R. Eller, J. L. Sessler, J. Am. Chem.
Soc. 2002, 124, 1134–1135; b) P. Anzenbacher Jr., D. S. Tyson,
K. Jurisková, F. N. Castellano, J. Am. Chem. Soc. 2002, 124,
6232–6233; c) D. S. Tyson, C. R. Luman, X. Zhou, F. N. Cas-
tellano, Inorg. Chem. 2001, 40, 4046–4071; d) D. S. Tyson, F. N.
Castellano, Inorg. Chem. 1999, 38, 4382–4383; e) D. S. Tyson,
I. Gryczynski, F. N. Castellano, J. Phys. Chem. A 2000, 104,
2919–2924; f) W. E. Ford, M. A. J. Rodgers, J. Phys. Chem.
1992, 96, 2917–2920; g) N. Armaroli, Chem. Soc. Rev. 2001,
30, 113–124.
a) F. M. MacDonnel, S. Bodige, Inorg. Chem. 1996, 35, 5758–
5759; b) S. Bodige, A. S. Torres, D. J. Maloney, D. Tate, G. R.
Kinsel, A. K. Walker, F. M. MacDonnel, J. Am. Chem. Soc.
1997, 119, 10364–10369; c) F. M. MacDonnel, M.-J. Kim, S.
Bodige, Coord. Chem. Rev. 1999, 185/186, 535–549; d) M.-J.
Kim, F.-M. MacDonnel, M. E. Gimon-Kinsel, T. Du Bois, N.
Asgharian, J. C. Griener, Angew. Chem. Int. Ed. 2000, 39, 615–
619; e) F. M. MacDonnel, M. D. Meser Ali, M.-J. Kim, Inorg.
Chem. 2000, 39, 203–225.
a) G. R. Newkome, C. N. Moorefield, F. Vögtle, Dendrimers
and Dendrons, Wiley-VCH, Weinheim 2001; b) J. M. J. Fréchet,
D. A. Tomalia, Dendrimers and Other Dendritic Polymers,
Wiley, Chichester 2001; c) Dendrimers, V: C. A. Schalley, F.
Vögtle, Top. Curr. Chem. 2003, 228, and previous volumes I–
IV.
a) J.-F. Nierengarten, D. Felder, J.-F. Nicoud, Tetrahedron Lett.
1999, 40, 273–276; b) J.-F. Nierengarten, C. R. Chim. 2003, 6,
725–733; c) E. Gumienna-Kontecka, Y. Rio, C. Bourgogne, M.
Elhabiri, R. Louis, A.-M. Albrecht-Gary, J.-F. Nierengarten,
Inorg. Chem. 2004, 43, 3200–3209.
S. Serroni, S. Campagna, A. Juris, M. Venturi, V. Balzani, D.
Denti, Gazz. Chim. Ital. 1994, 124, 423–427.
a) F. Vögtle, M. Plevoets, M. Nieger, G. C. Azzellini, A. Credi,
L. De Cola, V. De Marchis, M. Venturi, V. Balzani, J. Am.
Chem. Soc. 1999, 121, 6290–6298; b) M. Plevoets, F. Vögtle, L.
De Cola, V. Balzani, New J. Chem. 1999, 23, 63–69; c) D. S.
Tyson, C. R. Luman, F. N. Castellano, Inorg. Chem. 2002, 41,
3578–3586; d) T. H. Ghaddar, J. F. Wishart, J. P. Kirby, J. K.
Whitesell, M. A. Fox, J. Am. Chem. Soc. 2001, 123, 12832–
12836; e) J. Issberner, F. Vögtle, L. De Cola, V. Balzani, Chem.
Eur. J. 1997, 3, 706–712.
4,7-Bis[4Ј-(3ЈЈ,5ЈЈ-bis{3ЈЈЈ,5ЈЈЈ-bis[3ЈЈЈЈ,5ЈЈЈЈ-bis(benzyloxy)benzyl-
oxy]benzyloxy}benzyl)phenyl]-1,10-phenanthroline (L3G): 4,7-Bis(4Ј-
hydroxyphenyl)-1,10-phenanthroline (8) (40.0 mg, 0.11 mmol), den-
dritic Fréchet-type G3 bromide 12 (381.9 mg, 0.23 mmol), NaH
(9.7 mg, 0.24 mmol, 60% in paraffin) in dry DMF (15 mL). Col-
umn chromatography (SiO2, CH2Cl2/MeOH, 50:1 to 20:1) gave a
brownish viscous oil (360.0 mg, 93%). Rf = 0.55 (CH2Cl2/MeOH,
10:1). 1H NMR (400 MHz, CDCl3): δ = 4.86 (s, 16 H, OCH2), 4.89
(s, 8 H, OCH2), 4.92 (s, 32 H, OCH2), 4.95 (s, 4 H, OCH2), 6.49
(m, 12 H, Har), 6.61 (m, 26 H, Har), 6.65 (d, J = 2 Hz, 4 H, Har),
7.03 (AAЈ part of the AAЈBBЈ system, 4 H, Har), 7.18–7.34 (m, 80
H, Har), 7.36 (BBЈ part of the AAЈBBЈ system, 4 H, Har), 7.42 (d,
J = 5 Hz, 2 H, Har), 7.84 (s, 2 H, Har), 9.11 (d, J = 5 Hz, 2 H, Har)
ppm. 13C NMR (100 MHz, CDCl3): δ = 70.0, 70.1, 70.2, 70.3,
101.6, 101.7, 101.8 106.5, 106.6, 106.8, 115.2, 123.6, 124.0, 126.5,
127.6, 128.0, 128.6, 130.6, 131.1, 136.9, 139.3, 139.4, 139.5, 147.0,
148.1, 149.8, 159.1, 160.1, 160.2, 160.3 ppm. MS (MALDI-TOF,
DHB): m/z = 3515.9 (34) [M + H]+ , 1940.7 (24), 1621.5 (100).
[4]
Liquid–Liquid Extraction Procedure: Extraction studies were per-
formed at 25 1 °C in 2 cm3 microcentrifuge tubes by mechanical
shaking. The phase ratio V(org):V(w) was 1:1 (0.5 cm3 each); the
shaking period was 30 min. The extraction equilibrium was
achieved during this period. All samples were centrifuged after ex-
traction. The copper concentration in both phases was determined
radiometrically using γ-radiation [64Cu, NaI(Tl) scintillation
counter Cobra II/Canberra Packard]. The aqueous solution was
adjusted using 0.05 mol·dm–3 2-[N-morpholino]ethanesulfonic acid
(MES)/ NaOH (pH = 5.3–5.9).
[5]
[6]
Time-Resolved Laser-Induced Fluorescence Spectroscopy (TRLFS):
Fluorescence measurements were carried out by use of a spectrom-
eter system described elsewhere.[30] The ligands (L0G–L3G) were dis-
solved in CHCl3. The total concentration of the ligand was 1·10–5
mol·dm–3. The fluorescence of solutions with increasing concentra-
tion of added CuII trifluoromethanesulfonate were measured. The
ligand to CuII ratio was varied from 10:1 to 1:1. The fluorescence
of the non-complexed ligand was excited by 130 fs laserpulses at
266 nm. The repetition rate of the laser system was 1 kHz. The
emitted fluorescence was focussed into a 270 mm spectrograph (Ac-
ton Research) and the spectrum was measured by an intensified
CCD (charged coupled device) camera (LaVision). The gate of the
camera system was set to be 120 ps and the observed wavelength
range was set from 350 nm to 510 nm. The range for time-resolved
measurements was limited from 0 to 4000 ps with steps of 25 ps.
[7]
[8]
[9]
N. D. McClenaghan, R. Passalacqua, F. Loiseau, S. Cam-
pagna, B. Verheyde, A. Hameurlaine, W. Dehaen, J. Am. Chem.
Soc. 2003, 125, 5356–5365.
a) D. Tzalis, Y. Tor, Tetrahedron Lett. 1996, 37, 8293–8296; b)
Y. To r, C. R. Chim. 2003, 6, 755–766.
a) P. C. Alford, M. J. Cook, A. P. Lewis, G. S. G. McAuliffe, V.
Skarda, A. J. Thomson, J. L. Glasper, D. J. Robbins, J. Chem.
Soc., Perkin Trans. 2 1985, 705–709; b) F. H. Case, P. F.
Strohm, J. Org. Chem. 1962, 27, 1641–1643; c) F. H. Case, J.
Org. Chem. 1951, 16, 1541–1545.
E. H. Vickery, L. F. Pahler, E. J. Eisenbraun, J. Org. Chem.
1979, 44, 4444–4446.
a) C. J. Hawker, J. M. J. Fréchet, J. Am. Chem. Soc. 1990, 112,
7638–7647; b) C. J. Hawker, J. M. J. Fréchet, J. Chem. Soc.
Chem. Commun. 1990, 1010–1013.
a) P. Ballesteros, R. M. Claramunt, J. Elguero, Tetrahedron
1987, 43, 2557–2564; b) S. Strömberg, M. Oksman, L. Zhang,
K. Zetterberg, Acta Chem. Scan. 1995, 49, 689–695; c) S. Ser-
[10]
[11]
Acknowledgments
Financial support by the Saxon State Ministry of Science and Art
(project 4–7531.50–03–0370–01/4) is acknowledged with thanks.
We are grateful for advice by Dr. H.-J. Josel (Roche Diagnostics)
during earlier studies on luminescent complexes.
[12]
[13]
[1] a) C. R. Luman, F. N. Castellano, in: Comprehensive Coordina-
tion Chemistry II: From Biology to Nanotechnology (Eds: J. A.
McCleverty, T. J. Meyer), Elsevier-Pergamon, Amsterdam,
Boston, Heidelberg, London, New York, Oxford, Paris, San
[14]
Eur. J. Inorg. Chem. 2005, 4501–4508
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4507

H. Stephan, G. Geipel, G. Bernhard, P. Comba, G. Rajaraman, U. Hahn, F. Vögtle
FULL PAPER
roni, S. Campagna, A. Juris, M. Venturi, V. Balzani, G. Denti,
Gazz. Chim. Ital. 1994, 124, 423–427; d) P. Maslak, R. D.
Guthrie, J. Am. Chem. Soc. 1986, 108, 2628–2636.
[23] S. Tyagi, B. J. Hathaway, J. Chem. Soc. Dalton Trans. 1983,
199–203.
[24] M. F. Ottaviani, S. Bossmann, N. J. Turro, D. A. Tomalia, J.
Am. Chem. Soc. 1994, 116, 661–671.
[15] a) B. J. Hathaway, in: Comprehensive Coordination Chemistry
(Eds.: G. Wilkinson, R. D. Gillard, J. A. McCleverty), Perga- [25] G. Murphy, C. Murphy, B. Murphy, B. Hathaway, J. Chem.
mon, Oxford, 1987, vol. 5, 533–594; b) R. Mukherjee, in: Com-
prehensive Coordination Chemistry II: From Biology to Nano-
technology (Eds: J. A. McCleverty, T. J. Meyer), Elsevier-Perga-
mon, Amsterdam, Boston, Heidelberg, London, New York,
Oxford, Paris, San Diego, San Francisco, Singapore, Sydney,
Tokyo, 2004, vol. 5, 747–910.
Soc. Dalton Trans. 1997, 2653–2660.
[26] P. Comba, T. W. Hambley, N. Okon, “MOMEC, a molecular
modeling package for inorganic compounds”, University of
Heidelberg, www.comba-group.uni-hd.de, 1997.
[27] P. V. Bernhardt, P. Comba, Inorg. Chem. 1992, 31, 2638–2644.
[28] a) K. Amournjarusiri, B. J. Hathaway, Acta Crystallogr. Sect.
C 1991, 47, 1383–1385; b) M. T. Miller, P. K. Gantzel, T. B.
Karpishin, Inorg. Chem. 1998, 37, 2285–2290; c) K. J. Catalan,
S. Jackson, J. D. Zubkowski, D. L. Perry, E. J. Valente, L. A.
Felin, A. Polanco, Polyhedron 1995, 14, 2165–2171.
[29] a) D. Wang, G. R. Hanson, J. Magn. Reson. A. 1995, 117, 1–
8; b) D. Wang, G. R. Hanson, Appl. Magn. Reson. 1996, 11,
401–415.
[16] K. Gloe, P. Mühl, Isotopenpraxis 1983, 19, 257–260.
[17] Graphs about influence of time and pH on the CuII extraction
with dendritic ligands are available as Supporting Information.
[18] pKa of 1,10-phenanthroline = 4.93; D. A. Brisbin, W. A. E.
McBryde, Can. J. Chem. 1963, 41, 1135–1141.
[19] DCu is defined as the quotient of the relative amounts of the
CuII species present in the organic and aqueous phase.
[20] K. Gloe, P. Mühl, Isotopenpraxis 1979, 15, 236–239.
[21] Optimized structures of copper() complexes with dendritic
oxybathophenanthroline ligands LG0–LG3 as obtained by me-
chanics calculations are available as Supporting Information.
[22] C. K. Jørgensen, Acta Chem. Scand. 1955, 9, 1362–1377.
[30] G. Geipel, M. Acker, D. Vulpius, G. Bernhard, H. Nitsche, T.
Fanghänel, Spectrochim. Part A 2004, 60/1–2, 417–424.
Received: February 28, 2005
Published Online: October 5, 2005
4508
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 4501–4508