(Phthalocyaninato)copper(II) complexes fused with different numbers of 15-crown-5 moieties - Synthesis, spectroscopy, supramolecular structures, and the effects of substituent number and molecular symmetry

Article abstract of DOI:10.1002/ejic.200700148

Symmetrical (phthalocyaninato)copper(II) complexes Cu(Pc′) [Pc′ = Pc(15C5), Pc(opp-15C5)₂, Pc(adj-15C5)₂, Pc(15C5) ₃; Pc = unsubstituted phthalocyaninate, Pc(15C5) = 2,3-(15-crown-5)phthalocyaninate, Pc(opp-15C5)₂ = 2,3,16,17-bis(15-crown-5)phthalocyaninate, Pc(adj-15C5)₂ = 2,3,9,10-bis(15-crown-5)phthalocyaninate, Pc(15C5)₃ = 2,3,9,10,16,17-tris(15-crown-5)phthalocyaninate] (2-5) have been prepared by the reaction of corresponding heteroleptic bis(phthalocyaninato)europium complexes Eu(Pc)(Pc′) [Pc′ = Pc(15C5), Pc(opp-15C5)₂, Pc(adj-15C5)₂, Pc(15C5)₃, Pc(15C5)₄; Pc = unsubstituted phthalocyaninate] with Cu(OAc)₂ in dry dmf at 100°C. For the purpose of comparative studies, the symmetrical counterparts CuPc (1) and CuPc(15C5)₄ [Pc(15C5)₄ = 2,3,9,10,16,17,24, 25-tetrakis(15-crown-5)phthalocyaninate] (7) have also been prepared. These monomeric complexes have been characterized by spectroscopic methods in addition to elemental analysis. Having a series of closely related phthalocyanines with a different number and/or disposition of 15-crown-5 groups at the peripheral positions, the effects of 15-crown-5 substituent number and molecular symmetry on the electronic absorption spectra, infra-red (IR) spectra, and supramolecular structure formation induced by K⁺ ions have been investigated. Systematic studies on the formation of dimeric supramolecular structures of the series of monomers 2-6 reveal and confirm the previously proposed two-step three-stage process of K⁺-induced dimerization of phthalocyanines with three or four 15-crown-5 moieties. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200700148

FULL PAPER
DOI: 10.1002/ejic.200700148
(
Phthalocyaninato)copper(II) Complexes Fused with Different Numbers of 15-
Crown-5 Moieties – Synthesis, Spectroscopy, Supramolecular Structures, and
the Effects of Substituent Number and Molecular Symmetry
[a]
[a]
[a]
[b]
[a]
Ning Sheng, Yuexing Zhang, Hui Xu, Meng Bao, Xuan Sun,* and
Jianzhuang Jiang*[
a]
Keywords: Phthalocyanines / Crown ether / Supramolecular chemistry / Molecular symmetry
Symmetrical (phthalocyaninato)copper(II) complexes Cu(PcЈ)
PcЈ = Pc(15C5), Pc(opp-15C5) , Pc(adj-15C5) , Pc(15C5) ; Pc
unsubstituted phthalocyaninate, Pc(15C5) = 2,3-(15-crown-
have been characterized by spectroscopic methods in ad-
dition to elemental analysis. Having a series of closely re-
lated phthalocyanines with a different number and/or dispo-
sition of 15-crown-5 groups at the peripheral positions, the
effects of 15-crown-5 substituent number and molecular sym-
metry on the electronic absorption spectra, infra-red (IR)
[
=
2
2
3
5
5
5
)phthalocyaninate, Pc(opp-15C5)
)phthalocyaninate, Pc(adj-15C5)
)phthalocyaninate, Pc(15C5)
2
= 2,3,16,17-bis(15-crown-
= 2,3,9,10-bis(15-crown-
2
3
=
2,3,9,10,16,17-tris(15-
crown-5)phthalocyaninate] (2–5) have been prepared by the
reaction of corresponding heteroleptic bis(phthalocyanin-
ato)europium complexes Eu(Pc)(PcЈ) [PcЈ = Pc(15C5), Pc(opp-
spectra, and supramolecular structure formation induced by
+
K
ions have been investigated. Systematic studies on the
formation of dimeric supramolecular structures of the series
1
5C5)
tuted phthalocyaninate] with Cu(OAc)
For the purpose of comparative studies, the symmetrical
counterparts CuPc (1) and CuPc(15C5) [Pc(15C5)
,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninate]
7) have also been prepared. These monomeric complexes
2
, Pc(adj-15C5)
2
, Pc(15C5)
3
, Pc(15C5)
4
; Pc = unsubsti-
of monomers 2–6 reveal and confirm the previously proposed
two-step three-stage process of K -induced dimerization of
phthalocyanines with three or four 15-crown-5 moieties.
+
2
in dry dmf at 100 °C.
4
4
=
2
(
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
Introduction
their dimerization in a two-step three-stage process in the
presence of potassium ions in a mixed solvent of chloro-
form and methanol. Since then, significant efforts have
The design and preparation of supramolecular structures
have attracted significant research interest due to their great
potential applications in materials science and molecular
electronics. Phthalocyanines have been an important class
of molecular materials since their first synthesis early in the
[4]
been put into adding different numbers of 15-crown-5 voids
onto the phthalocyanine skeleton through asymmetric σ-
bonded substitution of the peripheral protons. However,
most probably because of the absence of a suitable effective
separation method for the mono-, bis-, tris-, and tet-
rakis(15-crown-5)-substituted phthalocyanine compounds,
which each have a high and similar polarity, only a few
tris(15-crown-5)-substituted phthalocyanine analogues have
[
1]
last century. Crown ethers have also found wide applica-
tion in molecular electronic devices due to their remarkable
recognition and metal-binding properties.[ The combina-
tion of these two functional subunits for the purpose of
constructing novel supramolecular structures with novel
multi-functional properties has stimulated wide research
interest since the 1980s.[
2]
[5]
been isolated. The main target of the present work is to
introduce different numbers of 15-crown-5 groups, from
one to four, at different peripheral positions of the phthalo-
cyanine ligand of (phthalocyaninato)copper complexes, and
then systematically study their spectroscopic and dimeric
supramolecular structure formation characteristics.
3]
The first trial in this direction was the preparation of
CuPc(15C5) in 1986 by three independent research
4
[
3]
groups.
Subsequently, these crown ether substituted
metal-free or metallo-phthalocyanines have been studied for
It is worth pointing out that the effects of lowering the
molecular symmetry of phthalocyanine molecules on the
[
[
a] Department of Chemistry, Shandong University, Jinan 250100, spectra have not yet been fully exploited. Most of the stud-
China
ies so far have focused on the spectral properties of phthalo-
Fax: +86-531-856-5211
E-mail: jzjiang@sdu.edu.cn
cyanine analogues with reduced molecular symmetry be-
b] Department of Chemistry, Jinan University, Jinan 250100,
China
[6]
cause of their lower π-system symmetry than D , which
4h
are obviously significantly affected by the change in the size
Supporting information for this article is available on the
WWW under http://www.eurjic.org/ or from the authors.
of the π-system.
3268
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3268–3275

(
Phthalocyaninato)CuII Complexes Fused with 15-Crown-5 Moieties
FULL PAPER
Figure 1. Schematic molecular structures of (phthalocyaninato)copper complexes fused with different numbers of 15-crown-5 moieties.
In this paper, we report the synthesis of a series of un- The first method involves a mixed cyclization of two
symmetrical
(phthalocyaninato)copper(II)
complexes, phthalonitrile (or isoindole) precursors in the presence of a
[
8]
namely CuPc(15C5) (2), CuPc(opp-15C5) (3), CuPc(adj- metal salt or organic base. As can easily be expected, the
2
1
5C5) (4), and CuPc(15C5) (5) as well as symmetrical separation of a series of closely related and isomeric phthal-
2 3
CuPc (1) and CuPc(15C5) (6) with zero, one, two, three, ocyanines obtained in this way has been a great challenge
4
and four 15-crown-5 voids attached at different positions for chemists. As a result, except for the two whole series of
of the phthalocyanine ring (Figure 1). Their spectroscopic phthalocyanine analogues, whose π-system itself has a
[6a,9]
properties have also been comparatively studied, trying to lower symmetry than D , reported by Kenny and Tian,
4h
reveal the effects of lowering the molecular symmetry of respectively, from the reaction between a tetraazaporphyrin
phthalocyanines. It is worth mentioning that in spite of the precursor and a phthalocyanine precursor and between a
very recent efforts on the heteroleptic bis(phthalocyanina- phthalocyanine precursor and a naphthalocyanine precur-
to)europium complexes Eu(Pc)(PcЈ) [PcЈ = Pc(15C5), sor, unsymmetrical phthalocyanine derivatives whose π-sys-
[
7]
Pc(opp-15C5) , Pc(adj-15C5) , Pc(15C5) , Pc(15C5) ],
tem itself still maintains the D4h symmetry prepared and
these effects could not be clearly revealed due to the attenu- isolated with this method as a whole series are still very
2
2
3
4
ation and/or covering of such effects by strong π-π interac-
tions in the double-decker molecules, which predominantly
control their spectral properties.
rare, limited to MPc[(R) (OCH CH OCH CH OCH -
n
2
2
2
2
2
10]
[
CH OCH3)8–n] (M = 2H), to the best of our knowledge.
2
The second pathway involves the ring-expansion reaction
of subphthalocyanine. Treatment of a new dinitrile in the
isoindole form with a subphthalocyanine led to the forma-
tion of phthalocyanine analogues with a 3:1 ratio of the two
dinitriles. This method, again, is not practical for the pres-
ent case. In this work, we employed a novel methodology
Results and Discussion
Synthesis
Two synthetic pathways have been reported so far to pre- using heteroleptic bis(phthalocyaninato) rare earth com-
pare unsymmetrical monomeric phthalocyanine analogues. plexes Eu(Pc)(PcЈ) [PcЈ = Pc(15C5), Pc(opp-15C5)
, Pc(adj-
2
Eur. J. Inorg. Chem. 2007, 3268–3275
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3269

N. Sheng, Y. Zhang, H. Xu, M. Bao, X. Sun, J. Jiang
Table 1. Analytical and mass spectrometric data for (phthalocyaninato)copper complexes 2–7.[a]
FULL PAPER
Compound
[M]+ (m/z)[b]
Analysis
H
C
N
[
c]
[c]
[c]
CuPc(15C5) (2)
765.3 (765.2)
955.4 (955.2)
955.5 (955.2)
1145.7 (1145.3)
CuPc(opp-15C5)
CuPc(adj-15C5)
CuPc(15C5) ·2CHCl
2
·2CH
3
OH (3)
OH (4)
(5)
58.48 (58.85)
58.84 (58.85)
50.71 (50.28)
5.11 (5.14)
5.22 (5.14)
4.15 (4.30)
10.38 (10.98)
10.29 (10.98)
8.20 (8.20)
2
·2CH
3
3
3
[
a] Calculated values given in parentheses. [b] By MALDI-TOF mass spectrometry. [c] Satisfactory elemental analysis data is not obtained
for this compound.
1
5C5) , Pc(15C5) , Pc(15C5) ] as the starting material. Re- shifts gradually and slightly to the red and the weak band
2 3 4
action with a large excess of copper acetate in dry dmf at at 411–435 nm to the blue upon an increase in the number
00 °C for 1.5 h provides two different kinds of (phthalocy- of 15-crown-5 substituents. Apart from the absorption posi-
aninato)copper compounds Cu(Pc) and CuPc(15C5) (n = tion, the appearance of the electronic spectra is also sensi-
1
n
1
–4) (2–6) in relatively good yields. Fortunately, all the 15- tive to the number of 15-crown-5 substituents. For example,
crown-5-substituted (phthalocyaninato)copper complexes the weak band in the range of 411–435 nm for 15-crown-5-
–6, except for 2, could be relatively easily separated and containing (phthalocyaninato)copper complexes 2–6, which
3
purified from its unsubstituted analogue CuPc (1) by simple is absent in the unsubstituted CuPc (1), gradually increases
filtration followed by general neutral alumina column in intensity and moves to the higher energy side coinciding
chromatography, due to the presence of 15-crown-5 moie- with the increase in the number of 15-crown-5 groups from
ties on the phthalocyanine ring of compounds 3–6. It is 2 to 6. This result clearly reveals the origin of this absorp-
worth noting that the symmetrical compound CuPc- tion which is associated with the 15-crown-5 substituents.
(
15C5) (6) together with CuPc (1) was actually obtained In combination with the fact that a similar band was ob-
4
from the simple tetramerization of 4,5-dicyanobenzo-15- served for all the 15-crown-5-substituted monomeric
[
3]
crown-5 or unsubstituted dicyanobenzene, in the presence phthalocyanines and even the alkoxy-substituted phthalo-
[
11]
of copper acetate.
cyanine derivatives,
this absorption can be attributed to
Because of the low solubility of CuPc(15C5) (2), similar the nǞπ* transitions arising from the oxygen lone pairs of
to that of CuPc, complex 2 could not be isolated from the electrons. This assignment is further confirmed by our re-
reaction between Eu(Pc)[Pc(15C5)] and Cu(OAc) . This cent calculation results on the electronic absorption spectra
2
compound, however, was actually prepared by the reaction of nonperipherally tetraalkoxy-substituted (phthalocyanin-
[
12]
between Cu(OAc) and metal-free H Pc(15C5), the latter of ato)lead complexes. It is also noteworthy that for the iso-
2
2
which was prepared and separated from mixed ring tetra- meric complexes 3 and 4, a very slight shift is still observed
merization of dicyanobenzene and 4,5-dicyanobenzo-15- for some of the absorption bands, indicating that the elec-
crown-5.
tronic absorption properties are also more or less dependent
All the newly prepared (phthalocyaninto)copper(II) on the substituent positions.
complexes 2–5 gave satisfactory elemental analysis results
as given in Table 1. They were further characterized by
Table 2. Electronic absorption data for (phthalocyaninato)copper
complexes 1–6 in CHCl .
3
spectroscopic methods. The MALDI-TOF spectra of all
+
these compounds showed the molecular ion [M] signals Compound
λ
max [nm] (logε)
with correct isotopic pattern (Table 1).
1
2
3
4
5
6
343 (4.50)
602 (4.22) 637 (4.19) 666 (5.02)
341 (4.55) 435 (3.62) 608 (4.24) 644 (4.26) 673 (4.87)
340 (4.58) 423 (3.75) 610 (4.29) 646 (4.28) 675 (4.88)
340 (4.48) 424 (3.75) 609 (4.17) 646 (4.17) 674 (4.77)
341 (4.61) 414 (4.01) 611 (4.35) 647 (4.38) 676 (4.95)
341 (4.53) 411 (4.09) 611 (4.26) 648 (4.28) 677 (4.93)
Electronic Absorption Spectra
The electronic absorption spectra of the series of (phthal-
ocyaninato)copper complexes 1–6 were recorded in CHCl3
and the data are summarized in Table 2. Figure 2 compares
As shown in Figure 2, except for the weak nǞπ* transi-
the UV/Vis spectra in the range of 300–900 nm of the whole tion band at ca. 420 nm, all the unsymmetrical (phthalocy-
series of compounds. All the absorption spectra show a typ- aninato)copper(II) complexes 2–5 display very similar ab-
ical broad Soret band at 340–343 nm, involving a couple of sorption features, which also resemble their symmetrical
electronic transitions dealing with the third occupied counterparts 1 and 6. This observation reveals that the ef-
HOMO and the first LUMO. The Q bands for these com- fect of lowering the molecular symmetry of phthalocyan-
pounds are observed in the range of 666–677 nm, with two ines only through asymmetric σ-bonded substitution of the
vibrational shoulders at 602–611 and 637–648 nm. In ad- peripheral protons is too small to be reflected in their elec-
dition, a weak band at 411–435 nm is also observed. Except tronic absorption spectra. Phthalocyanines with diminished
for the Soret band, both the absorption positions of the Q molecular symmetry through asymmetric σ-bonded substi-
band and the weak band at 411–435 nm show dependence tution of the nonperipheral protons are expected to provide
on the number of 15-crown-5 substituents. The Q band more information in this regard.
3270
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3268–3275

(
Phthalocyaninato)CuII Complexes Fused with 15-Crown-5 Moieties
FULL PAPER
(1), the characteristic pattern of the IR spectrum of
CuPc(15C5)4 (6) still remains simple, somewhat simpler
than those of 2–5, revealing the relatively higher molecular
symmetry of the former compound. The static molecular
geometry of CuPc (1) and CuPc(15C5) (6) suggests a D
4
4h
point group for their molecule, while 2, 3, 4, and 5, have a
C , D , C , and C point group, respectively. This is
2v
2h
2v
2v
clearly revealed by the larger number of vibrational modes
observed in the IR spectra of 2–5 compared with those of
either CuPc (1) or CuPc(15C5)4 (6) (Figure S1 and
Table S1; Supporting Information). The difference in the
characteristic pattern of IR spectra between the isomers 3
and 4 is clearly due to their different molecular symmetry.
Formation of Dimeric Phthalocyanine Supramolecular
Structures
Figure 2. The electronic absorption spectra of CuPc (1),
+
The K -induced cofacial dimer formation of monomeric
CuPc(15C5) (2), CuPc(opp-15C5)
2
(3), CuPc(adj-15C5)
2
(4),
CuPc(15C5)
3
(5), and CuPc(15C5)
4
(6) in CHCl
3
.
phthalocyanine derivatives substituted with three or four
1
5-crown-5 voids, in particular CuPc(15C5) , has been well
4
[
4a,5]
studied by Kobayashi and co-workers.
On the basis of
IR Spectra
corresponding results, a two-step three-stage process was
Because of the interest in the sandwich-type (tetrapyr- proposed for cofacial dimer formation of monomeric
role)metal complexes related to their potential applications phthalocyanine derivatives. In the present study, the forma-
+
in molecular electronics and magnetism, we have focused tion process of K -induced dimeric supramolecular struc-
our attention on the synthesis and structures of a series of tures of 15-crown-5-substituted (phthalocyaninato)metal
(
na)phthalocyaninato and/or porphyrinato rare earth com- complexes, in a two-step three-stage process, has been clearly
[13–16]
plexes in the past decade.
IR spectroscopic character- revealed and confirmed by studying the formation processes
istics of (na)phthalocyanine in these sandwich-type com- of (phthalocyaninato)copper complexes in CHCl3 mixed
plexes have also been systematically studied for the purpose with a trace amount of MeOH due to the availability of the
of investigating the intrinsic properties of these phthalocy- series of mono-, bis-, tris-, and tetrakis(15-crown-5)-substi-
[
17–19]
anine compounds.
However, except for the early ef- tuted (phthalocyaninato)copper complexes, in particular
forts paid to the metal-free and metalo-phthalocyanines CuPc(15C5) (2), CuPc(adj-15C5)2 (4), CuPc(15C5)3 (5),
without peripheral substituents and the recent work on the and CuPc(15C5) (6).
4
calculated spectra of several phthalocyanine compounds
Figure 3 compares the systematic changes in absorption
employing the DFT method, systematic investigation of the spectra of CuPc(15C5) (2), CuPc(adj-15C5)2 (4),
IR spectroscopy of monomeric phthalocyanine compounds CuPc(15C5) (5), and CuPc(15C5) (6) in CHCl upon ti-
3
4
3
seems not to have been conducted to date. Our compounds tration with KOAc in CHCl /MeOH (9:1, v/v) and the final
3
in the present work are therefore expected to give represen- spectra obtained when [CH COOK]/[compound] = 3.0 for
3
tative data for the series of peripherally substituted (phthalo- all these compounds are listed in Figure S2 (Supporting In-
+
cyaninato)metal complexes.
formation). It can be seen that after adding K ions, the
As clearly shown in Figure S1 and Table S1 (Supporting intense Q-band at 673 nm for 2 does not take a blue shift
Information), the presence of one, two, three, and four 15- but gradually attenuates in intensity. Moreover, no new
crown-5 moieties on the peripheral positions of the phthalo- peak appears in this Q-band region. These results indicate
cyanine ring in the molecules of compounds 2, 3 and 4, 5, the formation of linear (or noncofacial) dimeric supramo-
+
+
and 6 increases the number of IR-active modes. The com- lecular structure [CuPc(15C5)](K ) [CuPc(15C5)][(2)(K ) -
1
1
mon absorptions for the 15-crown-5-substituted complexes (2)]. This is also true for the formation of linear (or nonco-
2
–6 observed at 2954–2958, 2921–2924, 2871–2872, 2851– facial) dimeric supramolecular structure [CuPc(adj-15C5) ]-
2
–
1
+
+
+
2856, 1280–1287, and 1045–1047 cm , which are absent in (K ) [CuPc(adj-15C5) ] [(4)(K ) (4)] when K ions are
2 2 2
the spectrum of unsubstituted CuPc (1), are attributed to added to a solution of the (phthalocyaninato)copper com-
the asymmetric and symmetric C–H stretching vibrations pound with two 15-crown-5 moieties at the adjacent periph-
and C–O–C stretching vibrations of the 15-crown-5 groups, eral positions according to the experimental results shown
respectively. Nevertheless, the intensity of all these absorp- in Figure 3 and Figure S2 (Supporting Information).
tions has been found to increase along with the number of
5-crown-5 moieties from 2 to 6.
However, significant change in the electronic absorption
spectrum takes place after K ions are added to the solu-
+
1
It is also worth noting that despite of several additional tion of compound 5, see Figure 3 and Figure S2 (Support-
peaks observed for CuPc(15C5) (6) compared with CuPc ing Information). Along with the decrease of the Q-band
4
Eur. J. Inorg. Chem. 2007, 3268–3275
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3271

N. Sheng, Y. Zhang, H. Xu, M. Bao, X. Sun, J. Jiang
FULL PAPER
of 5 at 676 nm, a new band appears at 624 nm due to the
formation of cofacial dimeric supramolecule [CuPc-
+
+
(
15C5) ](K ) [CuPc(15C5) ] [(5)(K ) (5)]. This is in line
3 3 3 3
+
with the results found during the formation of K -induced
cofacial dimerization of phthalocyanine analogues with
three 15-crown-5 voids.
[
4a,5]
It is worth noting that the Soret
band at 341 nm for 5 also shifts to the shorter wavelength
+
(
335 nm) with addition of K . In line with the previous re-
[
4a,5]
ports,
[
with addition of K .
cofacial dimeric supramolecular structure
+
+
CuPc(15C5) ](K ) [CuPc(15C5) ] [(6)(K ) (6)] is formed
4 4 4 4
+
It is noteworthy that a similar result to that of 5 was
observed for compound 3 (Figures S2 and S3; Supporting
Information). When no changes occur anymore upon ad-
+
dition of excess K ions, the electronic absorption spectrum
can be ascribed to the cofacial dimeric supramolecular
+
structure [CuPc(opp-15C5) ](K ) [CuPc(opp-15C5) ] [(3)-
2
2
2
+
(
K ) (3)].
2
+
As a result, it has been found that K -induced cofacial
dimerization of phthalocyanines with three or four 15-
crown-5 voids, for instance compound 5 or 6, should pro-
ceed in the following manner: two monomeric 15-crown-5-
substituted phthalocyanine molecules combine with the
+
first K cation to form a linear dimer, which then combines
+
with the second K cation to form a linear or cofacial di-
mer, and finally transforms into a stable cofacial dimer
+
when the third and/or fourth K cation(s) are combined. In
+
other words, K -induced cofacial dimerization of phthalo-
cyanines with three or four 15-crown-5 voids should pro-
[
4a,5]
ceed according to the following three stages:
(1) The
first involves the formation of a linear (or noncofacial) di-
+
mer at a [K ]/[MPc(15C5) ] value of 0–0.5; (2) the second
4
+
in the region of 0.5 Յ [K ]/[MPc(15C5) ] Յ 1.5 involves
4
the transition from the linear (or noncofacial) dimer to the
+
cofacial dimer when the second and third K cations are
combined; (3) the third involves the complete formation of
+
a cofacial dimer at [K ]/[MPc(15C5) ] Ն 1.5.
4
In addition, to monitor the cofacial supramolecular for-
mation for compounds 5 and 3, the changes in absorption
of the so-called monomer band (at 676 nm) and the dimer
band (at 592 nm) for 5 (Tables 2 and 3), and monomer band
(
at 675 nm) and the dimer band (at 593 nm) for 3, were
+
+
recorded as a function of [K ]/[5] and [K ]/[3], respectively.
As shown in Figure 4 and Figure S4 (Supporting Infor-
mation), the concomitant change of the two characteristic
+
bands indicates that upon addition of K ions, monomer 5
or 3 is converted exclusively to the dimeric supramolecular
Table 3. Electronic absorption data for the supramolecular dimers
(
SD) formed from the 15-crown-5-substituted (phthalocyaninato)-
copper complexes 2–6 in CHCl upon titration with KOAc in
CHCl /MeOH (9:1, v/v).
3
3
Compound
λ
max [nm] (logε)
Figure 3. Changes in absorption spectra of CuPc(15C5) (2),
SD2
SD3
SD4
SD5
SD6
338 (4.45)
333 (4.45)
335 (4.37)
335 (4.44)
610 (4.19) 643 (4.20) 673 (4.61)
CuPc(adj-15C5)
CHCl upon titration with KOAc in CHCl
rows indicate the direction of the spectral changes. The final spectra
were obtained when [CH COOK]/[compound] = 3.0 (for 2, 4–6).
2
(4), CuPc(15C5)
3
(5), and CuPc(15C5)
4
(6) in
615 (4.31)
623 (4.18)
624 (4.33)
673 (4.22)
672 (4.36)
671 (4.22)
3
3
/MeOH (9:1, v/v). Ar-
3
334 (4.41) 389 (3.98) 637 (4.53)
3272
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© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 3268–3275

(
Phthalocyaninato)CuII Complexes Fused with 15-Crown-5 Moieties
FULL PAPER
structure. The formation process is similar to that of occurs in this region. For these present systems, this in-
+
+
MPc(15C5) (M = H , Zn, Co, Ni, Cu) in CHCl . However, cludes the data point of [K ]/[5 or 3] = 0.5. When [K ]/
4
2
3
probably due to the low solubility of these compounds in- [5 or 3] Ͼ 3, the slope of the plot approaches zero.
+
cluding complexes 4 and 2, about a threefold amount of K
K
ions (i.e. [K ]/[5 or 3] ≈ 3) is required to reach a steady state n K+ + 2 CuPc(15C5)
Figure 4 and Figure S4; Supporting Information), instead
of the value of 2 observed for other reported monomeric
+
↔ dimer·K+
(1)
n
n
(
It is worth pointing out that for all the crown ether sub-
stituted (phthalocyaninato)copper compounds, namely
CuPc(15C5) (2), CuPc(opp-15C5)2 (3), CuPc(adj-15C5)2
phthalocyanine counterparts.[
4a,5]
(
4), CuPc(15C5)3 (5), and CuPc(15C5)4 (6), when two
+
CuPc(15C5) units bind one K cation and start to form
n
the dimer in the first stage, the monomer–dimer conversion
proceeds with a very high formation constant, K =
1
0
10
2
–2
3
.0ϫ10 to 7.0ϫ10 L mol with n = 1 for Equa-
[
4a]
tion (1).
Conclusions
We have prepared a series of unsymmetrical (phthalocy-
aninato)copper(II) complexes 2–5, containing different
numbers and positions of 15-crown-5 substituents, from the
reaction of corresponding heteroleptic bis(phthalocyanin-
ato)europium complexes Eu(Pc)(PcЈ) with Cu(OAc) ·nH O.
2
2
It has been found that all the unsymmetrical compounds
–5 and the symmetrical analogues 1 and 6 display very
Figure 4. Variation of the absorbance 676 and 592 nm during ti-
2
3 3
tration of 5 in CHCl with KOAc in CHCl /MeOH (9:1). The curve
+
going up with [K ] represents the change at the dimer peak and similar absorption features, indicating that the electronic
should be referred to the right-hand axis, while that going down is absorption spectra of these compounds are not sensitive
the change at the monomer peak and should be referred to the left-
enough to show the change in the molecular symmetry due
hand axis.
to unsymmetrical substitution of 15-crown-5 moieties,
which however can be clearly reflected by their IR spectra.
Systematic studies over the formation of dimeric supramo-
Equation (1) shows the equilibrium between monomer 5
or 3 (upon addition of K ions) and the corresponding di-
+
lecular structures of the series of monomers 2–6 clearly re-
veal and confirm the previously proposed two-step three-
stage process of phthalocyanines with three or four 15-
mer. According to the method described by West and Pe-
[
20]
arce,
the monomer and dimer concentrations could be
crown-5 moieties in CHCl with trace amounts of MeOH
calculated from the spectral changes during titration, and
their relationship be depicted as shown in Figure 5 and Fig-
ure S5 (Supporting Information) for the present systems.
The region with a slope of ca. 2.0 indicates the dimerization
3
+
in the presence of K .
Experimental Section
General Remarks: 1,8-Diazabicyclo[5.4.0]undec-7-ene (dbu) and di-
cyanobenzene were purchased from Aldrich. n-Pentanol and N,N-
dimethylformamide (dmf) were freshly distilled from Na and CaH ,
2
respectively, under nitrogen. Column chromatography was carried
out on neutral alumina (SCRC, 200–300 mesh) with the indicated
eluents. All other reagents and solvents were used as received. 4,5-
Dicyanobenzo-15-crown-5,[
4,21]
Eu(Pc)(PcЈ) [PcЈ
Pc(15C5) Pc(15C5)
(6) were prepared according to published
procedures. H NMR spectra were recorded with a Bruker DPX
00 spectrometer (300 MHz) in [D ]dmso. Spectra were referenced
internally by using the residual solvent resonance (δ = 2.49 for [D ]-
dmso) relative to SiMe . Electronic absorption spectra were re-
= Pc(15C5),
[
7]
Pc(opp-15C5)
2
,
Pc(adj-15C5)
2
,
3
,
4
],
CuPc
1),[ and CuPc(15C5)
22]
[4]
(
4
1
3
6
6
4
corded with a Hitachi U-4100 spectrophotometer. MALDI-TOF
mass spectra were measured with a Bruker BIFLEX III ultra-high
resolution mass spectrometer with α-cyano-4-hydroxycinnamic acid
as matrix. Elemental analyses were performed by the Institute of
Chemistry, Chinese Academy of Sciences.
Figure 5. Plots of log[5] vs. log[(5)(K+)
CHCl /MeOH. The inset shows the dependence of monomer and
dimer concentrations on [K ]/[5].
3
3
(5)] for CuPc(15C5) (5) in
Preparation of H
mixture of dicyanobenzene (76.8 mg, 0.60 mmol), 4,5-dicya-
Pc(15C5): According to a literature method,[23]
a
2
3
+
Eur. J. Inorg. Chem. 2007, 3268–3275
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3273

N. Sheng, Y. Zhang, H. Xu, M. Bao, X. Sun, J. Jiang
nobenzo-15-crown-5 (31.8 mg, 0.10 mmol), and an excess amount cation of China, Shandong University, and The Chinese University
FULL PAPER
of lithium (2.8 mg, 0.40 mmol) in n-pentanol (3 mL) was heated to
reflux under nitrogen for 2 h. After cooling to room temperature,
the resulting green solution was poured into methanol (100 mL)
containing a few drops of concentrated HCl. The precipitate was
collected by filtration and chromatographed on an alumina column
of Hong Kong is gratefully acknowledged.
[1] a) A. B. P. Lever, C. C. Leznoff, Phthalocyanine: Properties and
Applications, VCH, New York, 1989, vol. 1, 1993, vols. 2 and
3, 1996, vol. 4; b) N. B. McKeown, Phthalocyanine Materials:
using CHCl
band containing unsubstituted metal-free H
band containing the target compound H Pc(15C5) was developed
3
/MeOH (99:1) as the eluent. After eluting the first
Synthesis, Structure and Function, Cambridge University Press,
New York, 1998; c) K. M. Kadish, M. K. Smith, R. Guilard,
The Porphyrin Handbook, Academic Press, San Diego, 2000–
2
Pc, the second green
2
which was collected and the solvent removed in a rotary evapora-
tor. Repeated chromatography followed by recrystallization from
2
003, vols. 1–20.
[
2] a) C. J. Pederson, J. Am. Chem. Soc. 1967, 89, 2495–2496; b)
C. Liu, D. Walter, D. Neuhauser, R. Baer, J. Am. Chem. Soc.
2003, 125, 13936–13937 and references cited therein.
CHCl
3
and MeOH gave pure H
2
Pc(15C5) as a blue powder (12 mg,
+
16%). MS: calcd. for C H N O [M] 704.2; found for
40 32 8 5
H
2
Pc(15C5) 704.8.
[3] a) A. R. Koray, V. Ahsen, O. Bekaroglu, J. Chem. Soc., Chem.
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Preparation of CuPc(15C5) (2): A mixture of H
2
Pc(15C5) (12 mg,
0
.017 mmol) and Cu(OAc) (15 mg, 0.08 mmol) in dry dmf (3 mL)
2
was heated to 100 °C for 1.5 h under a slow stream of nitrogen.
After cooling to room temperature, MeOH (30 mL) was poured
into the resulting blue solution. The precipitate was collected by
filtration and chromatographed on an alumina column using
[
4] a) N. Kobayashi, A. B. P. Lever, J. Am. Chem. Soc. 1987, 109,
7433–7441; b) O. E. Sielecken, M. M. van Tilborg, M. F. M.
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Hino, J. Am. Chem. Soc. 1996, 118, 1073–1085.
CH
the target compound CuPc(15C5) was then collected. Repeated
chromatography followed by recrystallization from CH Cl and
2 2
Cl /MeOH (99.5:0.5) as the eluent. The blue band containing
[
2
2
[
6] a) M. Aoudia, G. Cheng, V. O. Kennedy, M. E. Keny, M. A. J.
Rodgers, J. Am. Chem. Soc. 1997, 119, 6029–6039; b) J. Mack,
N. Kobayashi, K. Ishii, M. J. Stillman, Inorg. Chem. 2002, 41,
MeOH gave pure CuPc(15C5) as a blue powder (8 mg, 60%). It is
worth noting that a satisfactory elemental analysis result could not
be obtained for this compound even after repeated purification by
column chromatography and recrystallization due to its limited sol-
ubility in common organic solvent.
5350–5363.
[
[
[
7] N. Sheng, R. Li, C.-F. Choi, W. Su, D. K. P. Ng, X. Cui, K.
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3802.
Preparation of CuPc(opp-15C5)
CuPc(15C5) (5): A mixture of Eu(Pc)(PcЈ) [PcЈ = Pc(opp-15C5)
Pc(adj-15C5) , Pc(15C5) ] (20 mg) and a large excess amount of
Cu(OAc) (15 mg, 0.08 mmol) in dry dmf (3 mL) was heated to
00 °C for 1.5 h under a slow stream of nitrogen. After cooling to
2 2
(3), CuPc(adj-15C5) (4), and
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2
,
2
3
2
9] Q. Luo, B. Chen, M. Wang, H. Tian, Adv. Funct. Mater. 2003,
1
13, 233–239.
room temperature, MeOH (30 mL) was poured into the resulting
blue solution. The precipitate collected by filtration was then dis-
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Perkin Trans. 1 1995, 14, 1817–1823.
solved in CHCl
tration, the resulting product was then chromatographed on an alu-
mina column using CH Cl /MeOH (98.5:1.5 for 3 and 4, 98:2 for
) as the eluent. The blue band containing the target compound
3
. After removing the undissolved CuPc by fil-
[11] W.-F. Law, R. C. W. Liu, J. Jiang, D. K. P. Ng, Inorg. Chim.
Acta 1997, 256, 147–150.
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2
5
[
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CuPc(15C5)
n
(n = 2–4) (3–5) was then collected. Repeated
and
as green powders. Yield: CuPc(opp-
(3) (8 mg, 56%), CuPc(adj-15C5) (4) (7 mg, 53%), and
CuPc(15C5) (5) (10 mg, 61%).
chromatography followed by recrystallization from CHCl
MeOH gave pure CuPc(15C5)
5C5)
3
n
1
2
2
3
[
Supporting Information (see footnote on the first page of this arti-
cle)(see also the footnote on the first page of this article): IR spec-
tra of (phthalocyaninato)copper complexes 1–6 in the region of
–1
4
00–1800 cm . UV/Vis absorption spectra of monomers 2–5 and
corresponding dimers in CHCl and in CHCl /MeOH (9:1, v/v),
respectively; changes in absorption spectrum of CuPc(opp-15C5)
3) in CHCl upon titration with KOAc in CHCl /MeOH (9:1,
v/v); variation of the absorbance at 675 and 593 nm during titration
of 3 in CHCl with KOAc in CHCl /MeOH (9:1); plots of log[3]
(3)] for CuPc(opp-15C5) (3) in CHCl /MeOH;
3
3
2
(
3
3
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Arnold, J. Jiang, Chem. Eur. J. 2005, 11, 7351–7357; c) P. Zhu,
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vs. log[(3)(K )
2
2
3
–1
characteristic IR bands (cm ) of (phthalocyaninato)copper com-
plexes 1–6 with 2 cm– resolution.
1
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Financial support from the Natural Science Foundation of China
(grant nos. 20325105, 20431010), National Ministry of Science and
Technology of China (grant no. 2001CB6105-07), Ministry of Edu-
3274
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Eur. J. Inorg. Chem. 2007, 3268–3275

(
Phthalocyaninato)CuII Complexes Fused with 15-Crown-5 Moieties
FULL PAPER
c) Y. Bian, R. Wang, J. Jiang, C.-H. Lee, J. Wang, D. K. P. Ng,
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Received: February 1, 2007
Published Online: May 23, 2007
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Eur. J. Inorg. Chem. 2007, 3268–3275
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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3275