Synthesis and characterization of three covalently linked porphyrin-phthalocyanine pentamers with nucleophilic substitution

Article abstract of DOI:10.1016/j.ica.2010.03.022

In this paper the synthetic methods of three covalently linked porphyrin-phthalocyanine heteropentamers, containing four units of porphyrin linked to a central phthalocyanine (Mpor-LPc; M = 2H, Fe, L = Zn, Fe), are described. The synthetic strategy is on

Full text of DOI:10.1016/j.ica.2010.03.022

Inorganica Chimica Acta 363 (2010) 2180–2184
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Inorganica Chimica Acta
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Synthesis and characterization of three covalently linked porphyrin-phthalocyanine
pentamers with nucleophilic substitution
*
Samira Osati, Nasser Safari , Parisa Rajabali Jamaat
Department of Chemistry, Faculty of Science, Shahid Beheshti University, G.C. Evin, 1983963113 Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper the synthetic methods of three covalently linked porphyrin-phthalocyanine heteropenta-
mers, containing four units of porphyrin linked to a central phthalocyanine (Mpor-LPc; M = 2H, Fe,
L = Zn, Fe), are described. The synthetic strategy is on the basis of nucleophilic substitution reactions
between [1,8,15,22-tetra nitro phthalocyanines] and [5-(4-hydroxy phenyl)-10,15,20-triphenyl porphy-
rins] as the phenolic alcohols. Porphyrins are linked with oxygen as spacer through meso position of phe-
nyl group to phthalocyanines. These macromolecules were characterized by 1H NMR, UV–Vis, IR,
fluorescence and mass spectroscopy. The electronic absorption spectrums of the hetero-dyad systems
changed significantly upon coupling and showed a great red shift in the phthalocyanine Q-bands. These
changes confirm the electron-donating effects of the porphyrin units and the extension of conjugated g-
systems. The emission spectra of the products supports intramolecular energy and charge transfer
between the sub-units.
Received 9 September 2009
Received in revised form 8 March 2010
Accepted 11 March 2010
Available online 16 March 2010
Keywords:
Phthalocyanine
Porphyrin
Oxy-bridge
Pentamer
Nucleophilic substitution
Leaving group
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
Different synthetic strategies have been used to prepare multi
porphyrin-phthalocyanine arrays. These methods are based on
Porphyrins and phthalocyanines represent two related groups
of very versatile macrocyclic organic molecules. Metalloporphyrins
are widely studied as biomimetic models for several biological re-
dox processes [1], and have been extensively used in chemical,
electrochemical [2] and photochemical analyses.
Metallophthalocyanines are widely used molecules in electro-
catalyst [3], infrared sensors [4], and nonlinear optics [5] and pho-
todynamic therapy agents [6,7]. They can also be useful for oxygen
reduction in fuel cell technology [8].
Conjugates of porphyrins and phthalocyanines are very inter-
esting structures for various reasons. The most important reason
is that these macrocycles have complementary absorptions in the
visible region and the emission spectra of phthalocyanines do not
show significant overlap with those of the porphyrins. The fluores-
cence quantum yields of phthalocyanines are 6–10 times higher
than porphyrins [9]. Another reason is the stability of these mole-
cules. Phthalocyanines are generally more stable and more rigid
than porphyrins, so they oxidize harder. As a result the electro-
chemical oxidation of a porphyrin can be performed in the pres-
ence of phthalocyanines. So these conjugates are good choices for
usage in molecular photonics, catalysis and light harvesting archi-
tectures with a good spectral coverage in the blue and red wave-
lengths [9].
electrostatic interactions in molecules with opposite charges,
host–guest interactions [10], the axial coordination [11] and cova-
lent linking’s by using functional groups [12–16].
The covalent linking of phthalocyanines to porphyrins was first
achieved by Gaspard and co-workers [17]. A dimmer of these com-
pounds with one porphyrin unit linked to a phthalocyanine unit
was shown to exhibit interesting charge transfer properties [18].
Phthalocyanine-porphyrin nonamers as a mixture of isomers of
tetra substitution of porphyrin dimmers have also been prepared
[19]. These arrays are stable enough against oxidant or reductant
agents [20,21] and can be used as multi-nuclear catalysts.
In this paper we report the synthesis, characterization and spec-
tral properties of covalently linked pentamers, one phthalocyanine
and four porphyrins linked through an oxy-bridge. Oxygen atoms
fully conjugate the five major
p systems and improve the efficiency
of the electron and energy transfer processes.
The synthesis started from the corresponding functionalized
metalloporphyrins (with one OH group) and metallophthalocya-
nines (with four NO2 group) instead of the synthetic route involv-
ing the self-cyclization reaction of phthalonitrile derivatives which
Nyokong and co-workers had been used [21]. For synthesis of
nitrophthalocyanines (2a and 2b) we used 3-nitrophthalonitrile in-
stead of 4-nitrophthalonitrile used in Nyokong’s works. This com-
pound broaden UV–Vis spectrum coverage of pentamers and larger
Q-bands shifts about 50–78 nm observed that have not been re-
ported before. Our method gives high yields relative to starting
* Corresponding author. Tel.: +98 21 22401765; fax: +98 21 22403041.
E-mail address: n-safari@cc.sbu.ac.ir (N. Safari).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.03.022

S. Osati et al. / Inorganica Chimica Acta 363 (2010) 2180–2184
2181
used porphyrins and phthalocyanines. This synthetic strategy can
be applied to prepare mixed metal arrays with high yields and will
be useful for the preparation of other substituted phthalocyanines
and has not been reported previously.
(H pyrrole) with the ratio of 3:1.1H NMR (300 MHz, CDCl3) para-
magnetic, 81.2 (H pyrrole), 12.2 (meta H phenyl), 13.4 (meta H
phenyl), 6.3 (para H phenyl), 8.0 (ortho H phenyl). MALDI-TOF-
MS: m/z: 690.15 [M+LiÀHÀCl]+. Anal. Calc. for C44H28N4OFeCl: C,
73.42; H, 3.89; N, 7.78. Found: C, 73.21; H, 3.92; N, 7.71%.
2. Experimental
2.3.2. Tetrakis [5-phenoxy-10,15,20, triphenyl porphyrin] zinc (II)
phthalocyanine (3a)
2.1. General
A mixture of 2a (0.025 mmol, 0.02 g), 1a (0.2 mmol, 0.126 g)
and dry K2CO3 (0.2 mmol, 0.027 g) in 20 cm3 dry DMF was refluxed
under nitrogen atmosphere for 6 h, and then K2CO3 was separated
by filtration. After the solvent evaporated, column chromatography
on basic alumina was performed. CH2Cl2 was used as an eluent and
nonreacted porphyrins were separated as the first cut. Toluene:
DMF mixture was used as a more polar solvent. By using solvent
mixtures that contained increasingly 10–25% DMF two separated
band were isolated. The first was a mixture of statistic products
and the second cut was the desired product with 52% yield. UV–
UV–Vis spectra were recorded on a Shimadzu UV–Vis 2100
spectrophotometer. The IR spectrums were recorded on a Bo-
mem-MB102 FT-IR spectrometer. 1H NMR and 13C NMR spectra
were recorded using a Bruker 300 MHz NMR. MALDI-TOF measure-
ments were performed with a Kratos Kompakt mass spectrometer.
A nitrogen laser (337 nm) was used for desorption and ionization
with an accelerating voltage of 20 kV. Ions were detected as posi-
tive on a time-of-flight mass detector in the reflector mode. Dithra-
nol was used as a matrix and LiBr was used as cationating agent.
Elemental analyses were performed on a LECO CHNS 932 instru-
ment. Fluorescence emission spectra were performed with a Var-
ian Cary Eclipse spectrofluorometer.
Vis (DMF): kmax/nm (log e): 421(5.4), 517(4.4), 550(4.1), 589(4.0),
654(4.2), 722(4.4). 1H NMR (300 MHz, DMSO-d6) the spectrum
was similar to 1a in addition to d: 7.6–7.6 (phthalocyanine H). IR
(KBr):
m
max, cmÀ1: 1261(aromatic C–O–C). MALDI-TOF-MS: m/z:
3097.05 [M+LiÀH]+. Anal. Calc. for C208H128N24O4Zn: C, 80.80; H,
2.2. Chemicals
4.14; N, 10.86. Found: C, 80.74; H, 4.18; N, 10.91%.
Pyrrole, benzaldehyde, 4-hydroxy benzaldehyde, potassium
carbonate, iron (II) chloride, zinc acetate, silica gel 60 for chroma-
tography and DMF were purchased from Merck.
1,8,15,22-Tetra nitro zinc (II) phthalocyanine (2a) and
1,8,15,22-tetra nitro iron (II) phthalocyanine (2b), were synthe-
sized as reported in the literature [22]. All solvent were dried using
standard methods prior to use.
2.3.3. Tetrakis [5-phenoxy-10,15,20, triphenyl porphyrin iron (III)
chloride] zinc (II) phthalocyanine (3b)
A mixture of 2a (0.025 mmol, 0.02 g), 1b (0.2 mmol, 0.136 g)
and dry K2CO3 (0.2 mmol, 0.027 g) in 20 cm3 DMF was refluxed un-
der nitrogen atmosphere for 6 h and then K2CO3 was separated by
filtration. After the solvent evaporated, column chromatography on
basic alumina was performed according to the method used for 3a
and 3b with 55% yield. UV–Vis (DMF): kmax/nm (log e): 419(5.4),
2.3. Synthesis
572(4.3), 512(4.2), 750(4.5), 1H NMR (300 MHz, DMSO-d6) para-
magnetic, d 79.24 (6H, pyrrole H), 72.10 (2H, pyrrole H). 1H NMR
(300 MHz, CDCl3), d 81.4 (8H, pyrrole H), 13.5 (3H, meta phenyl
H), 12.8 (1H meta phenyl H), 12.3 (3H, meta phenyl H), 11.7 (1H
2.3.1. [5-(4-Hydroxy phenyl)-10,15,20-triphenyl porphyrin] (1a) and
[5-(4-hydroxy phenyl)-10,15,20-triphenyl porphyrin] iron (III)
chloride (1b)
meta phenyl H). IR (KBr):
m
max, cmÀ1: 1261 (aromatic C–O–C).
A mixture of 4-hydroxybenzaldehyde (10 mmol, 1.25 g) and
benzaldehyde (30 mmol, 3 cm3) were added to 80 cm3 propionic
acid, under nitrogen atmosphere. Pyrrole (40 mmol, 2.8 cm3) was
added and the resulting mixture was refluxed for 1 h. After cooling
to room temperature, the mixture was filtered and washed three
times with hot water. Column chromatography on silica gel was
performed with dichloromethane/n-hexane (1:1) as eluent The
first major cut was TPP and the second cut was found to be (1a)
[26]. Evaporation of the solvent resulted 0.6 g (10%) of a purple so-
MALDI-TOF-MS: m/z: 3324.12 [M+3LiÀ3HÀ4Cl]+ Anal. Calc. for
C208H120N24O4Cl4Fe4Zn: C, 72.43; H, 3.47; N, 9.74. Found: C,
72.51; H, 3.49; N, 9.79%.
2.3.4. Tetrakis [5-phenoxy-10,15,20, triphenyl porphyrin iron (III)
chloride] iron (II) phthalocyanine (3c)
A mixture of 2b (0.025 mmol, 0.02 g), 1b (0.2 mmol, 0.136 g)
and dry K2CO3 (0.2 mmol, 0.027 g) in 20 cm3 DMF was refluxed un-
der nitrogen atmosphere for 6 h. The solvent evaporated and col-
umn chromatography was performed according to the method
lid 1a. UV–Vis (DMF): kmax/nm (log e): 420(5.4), 517(4.4), 550(4.1),
590(4.0), 654(4.2). 1H NMR (300 MHz, DMSO-d6, 25 °C) : d, ppm
À2.91 (s, 2H, N–H), 7.21–7.23 (d, 2H, phenyl H), 7.74–7.75 (m,
9H, phenyl H), 8.01–8.05 (d, 2H, phenyl H), 8.25–8.28 (d, 6H, phe-
nyl H), 8.75–8.78 (d, 6H, pyrrole H), 8.90–8.92 (d, 2H, pyrrole H),
9.96 (s, 1H, OH). MALDI-TOF-MS: m/z: 636.36 [M+LiÀH]+. Anal.
Calc. for C44H30N4O: C, 83.82; H, 4.75; N, 8.88. Found: C, 83.75;
H, 4.79; N, 8.91%.
used for 3a and 3c collected in 50% yield. UV–Vis (DMF): kmax
nm (log
): 419(5.5), 573(4.6), 619(4.4), 652(4.5) 725(4.6). 1H
NMR (300 MHz, DMSO-d6) paramagnetic, d 83.5 (8H, pyrrole H).
/
e
IR (KBr): m
max, cmÀ1: 1261(aromatic C–O–C). MALDI-TOF-MS: m/
z: 3302.88 [M+LiÀHÀ4Cl]+. Anal. Calc. for C208H120N24O4Cl4Fe5: C,
72.63; H, 3.48; N, 9.77. Found: C, 72.65; H, 3.49; N, 9.76%.
A mixture of 1a (2 mmol, 1.26 g) and iron (II) chloride (4 mmol,
0.795 g) in 30 cm3 dimethylformamide DMF was heated at 100 °C
3. Results and discussion
for 2 h while stirring under nitrogen for preventing
l-oxo dimer
formation [23]. Removal of DMF by evaporation resulted in a pur-
ple solid that was washed with an adequate amount of water in or-
der to eliminate the of extra iron chloride (II). The MALDI-TOF mass
spectra showed only a monomeric molecular ion peak, indicating
In this article we used nucleophilic aromatic substitution reac-
tions for the synthesis of substituted phthalocyanines in terms of
the leaving groups and nucleophiles used. NO2 is a good leaving
group for nucleophilic aromatic substitution reactions. In the SNAr
mechanism the rate determining step involves formation of a tet-
rahedral intermediate and its formation is promoted by the leaving
groups having strong electron withdrawing effects such as NO2
[24].
absence of
from dichloromethane with methanol and produced 87% yield.
UV–Vis (DMF): kmax/nm (log
): 419(5.2), 512(4.5), 588(4.3). 1H
NMR (300 MHz, DMSO-d6) paramagnetic, d 72.8 (H pyrrole), 80.1
l-oxo dimer. The crude product (1b) was recrystallized
e

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S. Osati et al. / Inorganica Chimica Acta 363 (2010) 2180–2184
Both aliphatic [25] and phenolic alcohols have been added to
to meta protons of phenyls for high spin iron (III) complex of tetra
phenyl porphyrin. Phenyl groups are perpendicular on the porphy-
rin ring, so the presence of (Cl) as an axial ligand causes different
conditions for the two parts of protons. Therefore meta protons
on the phenyl groups were splitted into two sets at 12.3 ppm
and 13.5 ppm. For compound 1b the same protons on the phenoxy
group appeared at 12.8 and 11.7 with ratio of 3:1 and a small shift
to higher fields relative to TPP.
nitrophthalonitrile successfully via nucleophilic displacement of
the nitro group. The nitro group has also been substituted with ste-
rically hindered aryl alcohols using K2CO3 as a base and DMF in rel-
atively high yields. Based on this strategy we used hydroxyl
porphyrins 1a and 1b, modified phenolic alcohols, as nucleophiles
and tetra substituted nitro phthalocyanines to synthesize the Por-
phyrin-phthalocyanine pentamers.
The synthetic route for the compounds presented in this work is
shown in Fig. 1. The compounds are abbreviated as indicated in
Fig. 1 and experimental section. H2TPP(OH) (1a) was synthesized
and metallated using iron (II) chloride in nitrogen atmosphere to
obtain FeTPPCl(OH) (1b). These compounds were characterized
by IR, UV–Vis, elemental analysis, MALDI-TOF mass spectroscopy
as well as 1H NMR spectroscopy. In the 1H NMR spectrum of 1a,
the OH on the phenoxy ring caused the splitting of pyrroles and
phenyl protons as is observable in Fig. 2. Pyrrole resonances in
compound 1a splitted into two sets with ratio of 1:3 at
8.7–8.9 ppm similar to the place reported for TPPH2 [26]. Unsubsti-
tuted phenyl protons were seen at the same place for TPPH2 on the
three phenyl rings, whereas proton signals on the phenoxy ring (H2
and H3 in Fig. 1) were shifted to higher fields. The splitting pattern
and integration of the signals are consistent with the structure
shown for compound 1a in Fig. 2. Paramagnetic 1H NMR is very
informative for characterization of 1b and the 1H NMR spectrum
of DMSO-d6 solution of 1b is presented in part A of Fig. 3. The Pres-
ence of paramagnetic iron (III) in 1b leads to the splitting of broad
pyrrole position protons to two sets with 1:3 ratios at 80.1 ppm
and 72.8. However the 1H NMR spectrum of 1b in a CDCl3 solution
shows all pyrrole protons at 81.4 ppm at 25 °C consistent with the
pyrrole position of FeTPPCl [27]. Furthermore the phenyl meta pro-
tons are splitted into two sets that confirms the hydroxylation of
one phenyl ring in compound 1b. The region of 11.7–13.5 is due
(ZnPc-(H2TPP)4) (3a) was synthesized using the reaction of 1a
with 2a in the presence of dry K2CO3 and DMF in 52% yield relative
to 2a. UV–Vis monitoring shows the reduction of 2a Q-bands at
672 nm and the growth of a new band at 722 nm. Our goal was
to prepare a phthalocyanine substituted with four porphyrins.
Since the commonly numbered 1- or 4-positions in phthalocya-
nines are known to be passive of high steric hindrance for further
substitutions we used an excess of porphyrins to complete the
reaction. The reaction was performed with 4:1 ratio (stochiometric
ratio) of porphyrin to phthalocyanine. Note, the final yields in the
stochiometric ratio of porphyrin to phthalocyanine were just 5%
less than the reported excess ratio. Therefore it seems this synthe-
sis strategy is very efficient for coupling porphyrin to phthalocya-
nines and has an advantage over previous methods, in that overall
yields are around 50%, while in other methods reported in litera-
ture, the yields are less.
The 1H NMR spectrum of 3a indicated combinatory signals of
their component 1a and 2a with elimination of signal due to the
phenoxy OH group. A broad peak from 7 to 8 ppm and a signal at
7.6 was due to 2a. The shift of ZnPc peaks to higher field confirmed
the electron-donating effects of porphyrin to phthalocyanine. The
UV–Vis spectrum of 3a showed characteristic peaks of porphyrin
and phthalocyanines. However a large shift of about 50 nm was
seen for the Q band of ZnPc in compound 3a relative to the mixture
of 1a and 2a, Table 1 (from 672 nm for ZnPc alone to 722 nm for
M= 2H 1a
N
N
M= Fe 1b
N
M
N
N
N
M
N
N
N
N
N
N
OH
M
O
O
O
N
3a = 1a+2a
3b = 1b+2a
3c = 1b+2b
K2CO3
DMF
N
N
N
L
+
N
N
N
NO2
N
O
N
NO2
N
N
N
N
L
N
N
L= Zn 2a
L=Fe 2b
N
O2N
N
N
N
N
M
M
N
N
O2N
N
N
Fig. 1. Synthetic route in preparing porphyrin-phthalocyanine pentamers. 3a is formed from reaction of 1a and 2a, 3b from reaction of 1b and 2a and 3c from reaction of 1b
and 2b.

S. Osati et al. / Inorganica Chimica Acta 363 (2010) 2180–2184
2183
Fig. 2. (A) 1H NMR spectrum of 1a in DMSO-d6 solution at room temperature, (B) assignment of 1a protons.
Fig. 3. Paramagnetic 1H NMR spectrum of 1b (A) and 3b (B) in DMSO-d6 solution at room temperature. H7 and H8 are pyrrole position signals shown in part B of Fig. 2.
Table 1
kmax nm/(log
e) due to Q-bands of phthalocyanines before and after reaction and
related shifts in UV–Vis spectrum at concentration of 10À5 mol/l in DMF.
Phthalocyanines Q-band before
reaction
Q-band after
reaction
Total
shift
2a
2a
2b
672 nm(4.8)
672 nm(4.8)
666 nm(4.9)
(3a) 722 nm(4.4)
(3b) 750 nm(4.5)
(3c) 725 nm(4.6)
50 nm
78 nm
59 nm
ZnPc in 3a). This observation suggests that presence of porphyrins
on the three position on phthalocyanine confer more electron-
donating effects on metallophthalocyanines complexes relative to
other isomers in literature. The IR spectrum of this compound
showed the elimination of the NO2 vibration at 1531 cmÀ1 and
the C–N stretching band at 1336 cmÀ1 in addition to the growth
of the peak of aromatic ether at 1261 cmÀ1 and the reduction of
the OH peak at about 3300 cmÀ1 as shown in Fig. 4. Another indi-
cation of this structure being correct was obtained from the mass
spectrum which had a molecular ion peak at m/z: 30 905.7.
[M+LiÀH]+ (Fig. 5).
Fig. 4. FT-IR spectrum of (A) mixture of 1a and 2a before reaction and (B) 3a after
reaction is complete.
in pentamer 3b. This showed electronic effects of ZnPc ring to
the porphyrin which affected the position of the pyrrole rings.
The MALDI-TOF mass spectrum also confirmed the formation of
the pentamer 3b with a molecular ion peak at m/z: 3324.12
[M+3LiÀ3HÀ4Cl]+. The Lithium adducts derived from exchange
of protons with Lithium ions, and this has been observed previ-
ously [28]. The MALDI-TOF mass spectrum of 1b, 3b and 3c shows
the mass ion peak without axial chloride such as similar structures
reported in literature however elemental analysis proved presence
(ZnPc-(Fe (TPP)4) (3b) as a mixed metal pentamer was synthe-
sized with 55% yield relative to 2a and characterized by IR, 1H
NMR, UV–Vis and mass spectroscopy. The IR spectrum shows the
elimination of NO2 peaks at 1529 cmÀ1. UV–Vis indicates a red
shift of about 78 nm from 672 nm for ZnPc in the mixture of 1b
and 2a to 750 nm for ZnPc in 3b (Fig. 6). The large red shift con-
firms electron communication between the porphyrin and phthal-
ocyanines rings. Paramagnetic 1H NMR spectrum of 3b is shown in
part B of Fig. 3. The pyrrole protons were again splitted into two
sets as expected. Opposite to 1b which was an iron porphyrin
monomer, intensity patterns of the pyrrole rings were reversed
of four axial chlorides [29,30]. Porphyrin
l-oxo dimmers, having
sterically hindered macrocycles, are not readily formed .The steric
hindrance of iron porphyrins in pentamers 3b and 3c prevent the

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S. Osati et al. / Inorganica Chimica Acta 363 (2010) 2180–2184
tions confirm high interaction between porphyrin and
phthalocyanine moieties.
4. Conclusion
In this work, we synthesized three conjugated phthalocyanine–
porphyrins that are connected through meso phenyl group with
etheric spacers. In our method, functionalized metalloporphyrins
and metallophthalocyanines were used and mixed metal arrays
were prepared. Characterization by UV–Vis, 1H NMR, MALDI-
TOF-MS, IR, elemental analysis and Fluorescence spectroscopy con-
firmed synthesis of these pentamers.
Acknowledgments
This study has been supported by Iranian National Science
Foundation and Research and Graduate Study Councils of Shahid
Beheshti University for financial support. We would like to thank
Dr. Farhad Raofie for his assistance with the MALDI-TOF spectral
analysis.
Fig. 5. MALDI-TOF MS spectrum of 3a with a molecular ion peak at m/z 3097.05
[M+LiÀH]+.
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Commun. 33 (2003) 1717.
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[24] E. Ben-Hur, W.S. Chan, K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The
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formation of
spectra [31].
l-oxo dimmers as indicated by MALDI-TOF mass
(FePc-(FeTPP)4) (3c) with five Fe center synthesized with 50%
yield relative to 2b and characterized by IR (elimination of NO2
vibration at 1536.7 cmÀ1 and C–N stretch at 1353 cmÀ1 and growth
of aromatic ether peak at 1261 cmÀ1), UV–Vis (red shift about
59 nm from 666 nm of FePc alone to 725 nm for FePc in 3c) and
1H NMR spectroscopy. The Paramagnetic 1H NMR spectrum of 3c
in DMSO-d6 solution at pyrrole proton region showed a broad peak
at 83.59 ppm about 3 ppm more downfield compared to TPPFeCl
[24]. The broadness of the peak is due to the overlapping of two
sets of pyrrole peaks. The MALDI-TOF mass spectrum of the precip-
itate clearly shows the mass ion peak at m/z 3302.88 correspond-
ing to [M+LiÀHÀ4Cl]+.
The emission spectra of compounds 3a, 3b and 3c in 405 nm (at
a vibronic band near the soret band of the porphyrin) and 650 nm
(near the Q band of phthalocyanine) were analyzed. There was a
quenching of singlet excited states of 1a, 1b, 2a and 2b when each
of them was selectively excited in pentamers. Energy transfer from
phthalocyanine to porphyrin is impossible because LUMO of por-
phyrin is higher than phthalocyanine but the reverse process can
occur. So 2a and 2b quenching was a combination of both charge
transfer and energy transfer, but the quenching of 1a and 1b moi-
ety in pentamers was only due to charge transfer. These observa-
[25] Z. Biyikioglu, I. Acar, H. Kantekin, Inorg. Chem. Commun. 11 (2008) 630.
[26] E. Ben-Hur, W.S. Chan, K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The
Porphyrin Handbook, vol. 5, 2003, p. 47.
[27] E. Ben-Hur, W.S. Chan, K.M. Kadish, K.M. Smith, R. Guilard (Eds.), The
Porphyrin Handbook, vol. 5, 2003, p. 121.
[28] J. Su, M. Mrksich, Langmuir 19 (2003) 4869.
[29] M. Kimura, T. Shiba, M. Yamazaki, K. Hanabusa, H. Shirai, N. Kobayashi, J. Am.
Chem. Soc. 123 (2001) 5636.
[30] T.E. Clement, D.J. Nurco, K.M. Smith, Inorg. Chem. 37 (1998) 1150.
[31] K.M. Kadish, M. Autret, Z. Ou, P. Tagliatesta, T. Boschi, V. Fares, Inorg. Chem. 36
(1997) 204.