Single-wall carbon nanotubes covalently linked with zinc (II) phthalocyanine bearing poly (aryl benzyl ether) dendritic substituents: Synthesis, characterization and photoinduced electron transfer

Article abstract of DOI:10.1016/j.dyepig.2013.05.003

A novel series of dendritic phthalocyanine-single-wall carbon nanotube nanoconjugates, zinc (II) phthalocyanine bearing poly (aryl benzyl ether) dendritic substituents covalently linked with single-wall carbon nanotubes through either ethylenediamine or hexamethylenediamine as the spacer linker, were prepared. The structures and morphologies of the dendritic phthalocyanine-single-wall carbon nanotube nanoconjugates were characterized by IR, Raman spectroscopy, transmission electron microscopy and thermal gravimetric analysis methods. The photophysical properties of the nanoconjugates were studied by steady-state and time-resolved fluorescence spectroscopy. The intramolecular electron transfer occurred from phthalocyanine (donor) to the carbon nanotubes (acceptor) by a photoinduced process. The electron transfer exchange rate constant and the electron transfer efficacy between the dendritic phthalocyanine and single-wall carbon nanotubes increased with decreasing length of spacer linker. These novel nanoconjugates were fundamentally important due to the synergy effects of carbon nanotubes and dendritic zinc phthalocyanine, which may find potential application as biological labels.

Full text of DOI:10.1016/j.dyepig.2013.05.003

Accepted Manuscript
Single-Wall Carbon Nanotubes Covalently Linked with Zinc (II) Phthalocyanine
Bearing Poly (aryl benzyl ether) Dendritic Substituents: Synthesis, Characterization
and Photoinduced Electron Transfer
Dandan He, Yiru Peng, Hongqin Yang, Dongdong Ma, Yuhua Wang, Kuizhi Chen,
Pingping Chen, Jiafang Shi
PII:
S0143-7208(13)00168-X
10.1016/j.dyepig.2013.05.003
DYPI 3940
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 21 January 2013
Revised Date: 2 May 2013
Accepted Date: 2 May 2013
Please cite this article as: He D, Peng Y, Yang H, Ma D, Wang Y, Chen K, Chen P, Shi J, Single-Wall
Carbon Nanotubes Covalently Linked with Zinc (II) Phthalocyanine Bearing Poly (aryl benzyl ether)
Dendritic Substituents: Synthesis, Characterization and Photoinduced Electron Transfer, Dyes and
Pigments (2013), doi: 10.1016/j.dyepig.2013.05.003.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Highlights:
ꢀ
ꢀ
ꢀ
Synthesis a series of dendritic phthalocyanine-spacer linker-SWNTs nanoconjugates.
Intramolecular electron transfer could occur from phthalocyanines to SWNTs.
Electron transfer rate and efficacy increase with decreasing spacer linker length.

ACCEPTED MANUSCRIPT
Single-Wall Carbon Nanotubes Covalently Linked with Zinc (II)
Phthalocyanine Bearing Poly (aryl benzyl ether) Dendritic
Substituents: Synthesis, Characterization and Photoinduced
Electron Transfer
1
∗ 1
2
1
2
1
Dandan He , Yiru Peng , Hongqin Yang , Dongdong Ma , Yuhua Wang , Kuizhi Chen ,
1
1
Pingping Chen , Jiafang Shi
1
College of Chemistry and Chemical Engineering, Fujian Provincial Key Laboratory of Polymer
Materials, Fujian Normal University, Fuzhou 350007, China
2
Key Lab of Optoelectronic Science and Technology for Medicine of Ministry of Education,
Fujian Normal University, Fuzhou 350007, China
Abstract䟛A novel series of dendritic phthalocyanine-single-wall carbon nanotube nanoconjugates,
zinc (II) phthalocyanine bearing poly (aryl benzyl ether) dendritic substituents covalently linked with
single-wall carbon nanotubes through either ethylenediamine or hexamethylenediamine as the spacer
linker, were prepared. The structures and morphologies of the dendritic phthalocyanine-single-wall
carbon nanotube nanoconjugates were characterized by IR, Raman spectroscopy, transmission electron
microscopy and thermal gravimetric analysis methods. The photophysical properties of the
nanoconjugates were studied by steady-state and time-resolved fluorescence spectroscopy. The
intramolecular electron transfer occurred from phthalocyanine (donor) to the carbon nanotubes
(
acceptor) by a photoinduced process. The electron transfer exchange rate constant and the electron
∗
Corresponding author. Tel.: + 86 591 8346 5156.
E-mail address: yirupeng@fjnu.edu.cn (Y. Peng).
1

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transfer efficacy between the dendritic phthalocyanine and single-wall carbon nanotubes increased with
decreasing length of spacer linker. These novel nanoconjugates were fundamentally important due to
the synergy effects of carbon nanotubes and dendritic zinc phthalocyanine, which may find potential
application as biological labels.
Keywords: Single-wall carbon nanotubes; Dendrimer; Phthalocyanine; Photoinduced electron transfer;
Photophysical properties; Synthesis
1. Introduction
Single-wall carbon nanotubes (SWNTs) have unique electronic, mechanism and structural
properties as well as chemical stability that make them ideal nano-materials for applications in energy
conversion, gas storage, sensing and biological applications [1-2]. However, processing SWNTs and
integrating them in real world applications were severely limited by a number of inherent shortcomings:
purification, manipulation and low solubility in organic solvents. In order to improve their solubility
and overcome the aggregation properties, various functionalized strategies, like covalent [3-5] and
noncovalent methods [6-9] were employed. For example, Gudi et al., reported on the functionalization
of SWNTs with ferrocene species, and on the result of a spectroscopic investigation suggested an
intramolecular electron transfer in the functionalized nanotubes [10]. Sun and coworkers functionalized
SWNTs with pyrene-containing dendra and found that the photo-excited pyrene moieties were
quenched by linked SWNTs via efficient intramolecular energy transfer [11]. Some previous work has
been reported on the preparation of phthalocyanine-SWNTs composites or nanoconjugates and their
photoinduced intramolecular electron transfer properties [12-17].
2

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A dendritic phthalocyanine is a metal complex encapsulated within the inner core of a dendrimer
bearing hydrophilic surface groups, which is considered as a new efficient light-harvesting system.
Functionalization of the SWNTs with a light-harvesting dendritic phthalocyanine would present a
particular strategy to attach a limited number of function groups onto the SWNTs surface, thus we
expected them to show better solubility, less aggregation and better photophysical properties. Besides,
functionalized SWNTs with electron-donor antenna chromophores through a covalent linkage which
may lead to a significant breakthrough in generating singlet excited energy and conversion into
chemical energy, leading to excellent electron-transfer properties. However, at present, there are few
examples of dendritic phthalocyanine functionalized carbon nanotubes reported.
In this paper, a novel series of dendritic phthalocyanine-SWNTs nanoconjugates, zinc (II)
phthalocyanine bearing poly (aryl benzyl ether) dendritic substituents covalently linked with SWNTs
through either ethylenediamine or hexamethylenediamine as the spacer linker, were synthesized and
characterized. The photophysical and photoinduced electron transfer properties of this novel series of
dendritic phthalocyanine-SWNTs nanoconjugates were studied by UV/Vis, steady-state and
time-resolved fluorescence spectroscopy.
2
Materials and Methods
Solvents for organic synthesis were reagent grade, and were dried according standard procedures.
All the other compounds were used as received. SWNTs-COOH: diameter of about 20 nm, a length of
1
-3 ꢀm and purity > 90%.
Raman spectra were measured at room temperature with a Renishaw micro-Raman spectroscopic
system (Renishaw Invia, UK) and a diode laser operating at a wavelength of 785 nm as an excitation
3

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source. The UV/Vis spectra were recorded with a Cary50 UV/Vis spectrophotometer. A Perkin-Elmer
ATR Fourier transform infrared spectrophotometer was used for IR data collection. Steady-state and
time-resolved fluorescence spectra were carried out on a FL900/FS920 fluorescence spectrophotometer.
Thermal properties of the samples were measured using a Mettler-Toledo TGA/SDTA851e at a heating
rate of 10℃ /min in nitrogen atmosphere. Transmission electron microscopy images were recorded on a
JEM-2010 transmission electron microscope at 200 kV accelerating voltage.
3
Experimental
3
.1 Synthesis of compound 1
Compound 1 and Compound 2 were synthesized according to the literature [18,19]. N-tert-
butyloxycarbonyl-1,2-ethylenediamine (N-Boc-ethylenediamine) was obtained by treatment of
1
,2-ethylenediamine (12 mL, 200 mmol) with di-tert-butyldicarbonate (23.2 mL, 100 mmol) in
anhydrous methanol (120 mL) at room temperature. The mixture was evaporated to dryness under
reduced pressure. The residue was dissolved in water (100 mL) and saturated with sodium carbonate.
The aqueous layer was exacted with ethyl acetate (40 mL) by three times. The combined organic layers
were dried by magnesium sulfate anhydrous and evaporated to give compound 1 as yellow oil. Yield
-
1
(
16.00 g), percentage yield (50 %). IR/cm : 3446, 2976, 2930, 1692, 1365, 1397, 1170, 1039, 955, 870.
1
3 2 2
H NMR (CDCl , 400MHz, δ/ppm): 5.00 (s, 1H, -NH-), 3.18 (t, 2H, -NHCH -), 2.80 (t, 2H, -CH -
3 2
close to amino), 1.45 (s, 9H, -CH ), 1.40 (s, 2H, -NH ). ESI-MS (m/z): 160. Found: 161
+
[
M+H] .Analysis calcd. For C
7
H
16
N
2
O
2, C: 52.50, H: 10.00, N: 17.50. Found: C: 52.54, H: 10.05, N:
1
7.53. [See SI-Fig.1-3]
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3.2 Synthesis of compound 2
N-tert-butyloxycarbonyl-1,2-hexamethylenediamine (N-Boc-hexamethylenediamine) was obtained
by treatment of 1,2-hexamethylenediamine (9.30 g, 80 mmol) with di-tert-butyl dicarbonate (9.28 mL,
4
0 mmol) in anhydrous methanol (80 mL) at room temperature. The mixture was evaporated to dryness
under reduced pressure. The residue was dissolved in water (80 mL) and saturated with sodium
carbonate. The aqueous layer was exacted with ethyl acetate (40 mL) by three times. The combined
organic layers were dried by magnesium sulfate anhydrous and evaporated to give compound 2 as a
-
1
yellow loil. Yield (9.33 g), percentage yield (54 %). IR/cm : 3349, 2980, 2929, 1693, 1529, 1450, 1360,
1
1
250, 1172, 864. H NMR (CDCl
3
, 400MHz, δ/ppm): 4.71 (s, 1H, -NH-), 3.06 (t, 2H, -NHCH
2
-), 2.63
(
t, 2H, -CH
2
2 3 2
- close to amino), 1.64 (s, 2H, -NH ), 1.00-1.50 (s, 17H, -CH ,-CH -). ESI-MS (m/z): 216.
+
Found: 217 [M+H] . Analysis calcd. For C11
H
24
N
2
O
2, C: 61.11, H: 11.11, N: 12.96. Found: C: 61.15, H:
11.14, N: 13.03. [See SI-Fig.4-6]
3
.3 Synthesis of SWNTs 3 and SWNTs 4
To a suspension of SWNTs-COOH (100 mg) in dry dimethyl formamide (DMF) (20 mL) which
was sonicated in an ultrasonic washer for 30 min were added N-(3-dimethylaminopropyl)-N′-
ethylcarbodiimide hydrochloride (EDC·HCl) (100 mg), 1-hydroxy-benzotriazole (HOBt) (100 mg) and
compound 1 (0.25 g). The mixture was stirred at room temperature under nitrogen for 36 h. The
solution was filtered and the black solid was washed with DMF, dichloromethane (CH Cl ) and
2
2
diethyl ether affording functionalized SWNTs 3. Instead of compound 1 we used compound 2 (0.42 g)
and the same reaction procedure to obtain SWNTs 4.
3
.4 Synthesis of SWNTs 5 and SWNTs 6
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To a suspension of SWNTs 3 (10 mg) in dry CH Cl (5 mL) which was sonicated for 30 min was
2
2
added trifluoroacetic acid (TFA) (1 mL). The reaction mixture was stirred at room temperature under
nitrogen for 2 h. The solution was filtered and the black solid was washed with CH Cl and dry ethanol
2
2
affording functionalized SWNTs 5. The same reaction procedure leads to obtain SWNTs 6.
3
.5 Synthesis of DZnPc 7
Tetra-[3,5-di-(4-cyanobenzyloxy)benzyloxy] zinc (II) phthalocyanine was synthesized by
condensation of 3,5-di-(4-cyanobenzyloxy)benzyloxy phthalonitrile in the presence of acetate zinc in
6
0% yield [20]. The tetra-[3,5-di-(4-carboxylicbenzyloxy)benzyloxy] zinc (II) phthalocyanine DZnPc
was obtained by hydrolyzed tetra-[3,5-di-(4-cyanobenzyloxy)benzyloxy] zinc (II) phthalocyanine
7
-
1
(
0.50 g, 0.2mmol) in NaOH as a green solid[21]. Yield (0.36 g), percentage yield (82%). IR/cm : 3300,
1
2
4
7
930, 1690, 1600, 1450, 1430, 1318, 1295, 1250, 1153, 1067, 1020, 822, 580; H NMR (DMSO-d
6
,
00MHz, δ/ppm): 7.90-7.92 (d, J=8Hz, 16H, HOOCPh-H), 7.50-7.52 (d, J=8Hz, 16H, HOOCPh-H),
.18 (s, 4H, Pc-H), 7.04-7.06 (d, J=8Hz,4H, Pc-H), 6.92-6.93 (d, J=4Hz, 4H, Pc-H), 6.71 (s, 4H,
Ar-H),6.55 (s, 4H, Ar-H), 5.23 (s, 4H, PhCH
2
2 2
O), 5.14 (s, 4H, PhCH O), 5.08 (s, 4H, PhCH O).
+
MALDI-TOF-MS (m/z): 2201. Found: 2203 [M+2] .Analysis Calcd. For C124
N
8
H
88
O28Zn (%): C:
7
0.02, H: 4.14, N: 5.27. Found: C: 70.01, H: 4.16, N: 5.29. (See SI-Fig.7-9)
3
.6 Synthesis of SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9
To a suspension of SWNTs 5 (10 mg) in anhydrous DMF (20 mL) which was sonicated for 30 min
were added EDC·HCl (100 mg), HOBt (100 mg) and the dendritic phthalocyanine DZnPc 7 (20 mg)
were added. The reaction mixture was continuously stirred at room temperature under nitrogen for 36 h.
2 2
The solution was filtered and the black solid was washed with CH Cl and anhydrous ethanol affording
SWNTs-E-DZnPc 8. According to the above procedure, SWNTs 6 (10 mg) was treated with EDC·HCl
6

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(
100 mg), HOBt (100 mg) and the dendritic phthalocyanine DZnPc 7 (20 mg) to give
SWNTs-H-DZnPc 9. The structures of SWNTs 5, SWNTs 6, SWNTs-E-DZnPc 8 and
SWNTs-H-DZnPc 9 were characterized by IR, Raman spectroscopy, transmission electron microscopy
and thermal gravimetric analysis methods which would be discussed in the following chapter.
4. Results and discussion
The synthetic route for the dendritic phthalocyanine-single-wall carbon nanotube nanoconjugates
was shown in scheme 1.
4
.1 Synthesis and characterization
The carbodiimide-active amidation reaction was used to functionalize the surface bound
carboxylic acid groups the SWNTs (SWNTs-COOH) with a functional dendritic phthalocyanine
DZnPc 7 using either ethylenediamine or hexamethylenediamine as a spacer linker in DMF. In brief,
compound 1 was firstly obtained by reaction of ethylenediamine with 2 equivalents of di-tert-butyl
dicarbonate. Then, SWNTs 3 with Boc protecting groups were obtained by reaction of SWNTs-COOH
with EDC·HCl, HOBt and compound 1 in DMF. After that, the Boc protecting groups of SWNTs 3
2 2
were removed by using 25-50% TFA in CH Cl affording SWNTs 5 with amine groups. The dendritic
phthalocyanine DZnPc 7 was successfully synthesized via a convergent approach. Its structure was
1
unambiguously characterized by means of elemental analysis, IR, MALDI-TOF-MS and H NMR [20].
Finally, the coupling reaction between the amine groups of SWNTs 5 and the carboxylic groups of the
dendritic phthalocyanine DZnPc 7 in the presence of EDC·HCl and HOBt gave a nanoconjugate
SWNTs-E-DZnPc 8 with ethylenediamine as the spacer linker through amidation reaction. The similar
synthetic procedure was carried out to obtain a nanoconjugate SWNTs-H-DZnPc 9 with
hexamethylenediamine as the spacer linker. The constitutions, structures and morphologies of
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SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 were characterized by combination of analytical
techniques, such as IR, Raman spectroscopy, transmission electron microscopy (TEM) and thermal
gravimetric analysis (TGA).
The morphologies of the SWNTs-COOH, SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 were
studied by TEM. The images of SWNTs-COOH, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 are
shown in Figure 1. The image of pristine SWNTs-COOH showed a clean sidewall with a diameter of
about 20 nm (Fig.1 (a)). The black spots originated from the dendritic phthalocyanine indicated by
white circles on the SWNTs, evidence of the existence of the dendritic phthalocyanine on the
SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 with diameters of about 23 and 24 nm, respectively
(
Fig.1 (b) and Fig.1 (c).
Further evidence to support covalent functionalization of SWNTs was found in the IR spectra.
Figure 2 showed the IR spectra of SWNTs-COOH, SWNTs-E-DZnPc 8, SWNTs-H-DZnPc 9 and
-
1
DZnPc 7. A symmetrical C=O stretching at 1733 cm was assigned to the vibration of COOH moieties
-
1
of SWNTs-COOH. SWNTs-E-DZnPc 8, SWNTs-H-DZnPc 9 both displayed band at 1720 cm ,
which was matched with the vibration of the amide functional groups after the COOH moieties of
SWNTs being reacted with either ethylenediamine or hexamethylenediamine [22]. Finally, the IR
spectra of SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 also displayed other bands that were
coincident with those displayed by DZnPc 7.
Raman spectroscopy provided essential and useful information that the dendritic phthalocyanines
have been successful covalently attached to the carbon nanotube sidewalls. Raman spectra of the
-
1
nanoconjugates were shown in Figure 3. There were two principal bands at about 1330-1380 cm (D
-
1
band) and 1400-1600 cm (G band). The former was used to indicate the density of the defects for the
8

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SWNTs and had been used to monitor the process of covalent functionalization which transformed
2
3
from sp to sp site; while the latter could be used to estimate the level and distribution of modification
[
23]. Upon excitation at 785 nm, the intensity of SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 at 1386
-
1
cm was stronger than that of the pristine SWNTs-COOH, which suggests a significant modification
after the addition of phthalocyanine via a covalent bond [24-25]. Besides, some new features located at
-
1
6
82 and 749 cm for SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 were assigned to the δ vibration of
macromolecular zinc phthalocyanine, which can be clearly observed in Fig.3 [26]. The above results
confirmed the presence of zinc phthalocyanine particles on the SWNTs. Furthermore, radial breathing
modes (RBMs) were very sensitive to diameter and structure of the nanotubes. The RBM bands were
-
1
-1
observed between 166 and 266 cm for the all compounds. The peaks at 266 and 166 cm were hardly
discernible for the pristine SWNTs, but obviously observed for the functionalized SWNTs. This result
implied that the nanoconjugates were enriched on the nanotubes with slightly larger diameters after
reaction.
The amounts of dendritic phthalocyanine covalently linked with the SWNTs were determined by
TGA. Figure 4 showed the thermal decomposition profiles of SWNTs-COOH, DZnPc 7,
SWNTs-E-DZnPc
8 and SWNTs-H-DZnPc 9. SWNTs-COOH, SWNTs-E-DZnPc 8 and
SWNTs-H-DZnPc 9 presented a loss of weight about 8.9 %, 21 % and 32 %, respectively, at 650°C.
The initial mass loss for each sample before 200°C may be attributed to the solvent loss, therefore the
corrected weight losses due to the functional groups on nanotubes were then estimated to be 12 % for
SWNTs-E-DZnPc 8, 23 % for SWNTs-H-DZnPc 9 and 50 % for DZnPc 7. A simple calculation
permitted a loss of weight of 28% to be estimated if all carboxylic groups of the SWNTs-COOH (the
content of -COOH: 2.73%) were functionalized by the dendritic phthalocyanine. So a weight loss at
9

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about 12 % and 23 % indicated that not all carboxylic groups on the SWNTs have been reacted. This
result corresponds with the calculated result that one dendritic zinc phthalocyanine for about 614 and
1
345 carbon atom for SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 [27].
.2 Photophysical properties
4
The UV/Vis absorption spectra of SWNTs-COOH, DZnPc 7, SWNTs-E-DZnPc 8 and
SWNTs-H-DZnPc 9 were shown in Figure 5. The dendritic phthalocyanine DZnPc 7 showed a
B-band at 350 nm and a Q-band at about 685 nm. Additionally, there is a UV band at 290 nm, which
can be assigned to dendritic substituent chromophores. The van Hove singularities of SWNTs [28]were
observed through the recorded range between 300 and 800 nm. The UV/Vis absorption spectra of
SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 nanoconjugates provided unquestionable evidence for
the existence of both constituents: SWNTs and dendritic phthalocyanines. Therefore, the electronic
structure of the SWNTs was largely preserved.
Figure
6 showed the fluorescence spectra of DZnPc 7, SWNTs-E-DZnPc 8 and
SWNTs-H-DZnPc 9 in DMF. Upon excitation at 610 nm, DZnPc 7 exhibited fluorescence emissions
at 708 nm, with the fluorescence quantum yield of 0.10 which was calculated according to eq.1 [29]
and lifetime (τ) of 2.92 ± 0.29 ns. While the SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 exhibited
about 98% and 97% quenching of the phthlocyanine’s emission at 715 and 750 nm, respectively.
Excitation at different wavelength (350, 610 nm) also showed a similar quenching for the emission of
phthalocyanines (See SI-Fig.10-13), supporting the presence of an electron-transfer process from the
dendritic phthalocyanine to the carbon nanotubes through the spacer linker. The intensity of the
emission bands increased with the addition of an equimolar amount of free dendritic phthalocyanine
into the solution of SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 (See SI-Fig.14-15), further
10

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evidenced the fact that intramolecular electron transfer did occur between dendritic phthalocyanine
(
electron donor) and the carbon nanotubes (electron acceptor) during a photoinduced process.
Fx
AZnPc
Ax
Φx
=
ΦZnPc
×
×
eq.1
FZnPc
Where ΦZnPc is the fluorescence quantum yield of ZnPc in DMF, F
x
is the fluorescence of integral of
either SWNTs-E-DZnPc 8 or SWNTs-H-DZnPc 9, FZnPc is the fluorescence of integral of ZnPc, AZnPc
is the absorbance of ZnPc and A
SWNTs-H-DZnPc 9.
x
is the absorbance of either SWNTs-E-DZnPc 8 or
The fluorescence lifetimes (τ) of the SWNTs-E-DZnPc 8, SWNTs-H-DZnPc 9 and DZnPc 7 were
studied by time-resolved spectroscopy. The fluorescence decay curves of SWNTs-E-DZnPc 8,
SWNTs-H-DZnPc 9 and DZnPc 7 were shown in Figure 7. The fluorescence lifetimes were found to
-
t/τ1
-t/τ2
fit a mono-exponential function: f (t) = A + B
1
e
+ B
2
e
. The fitting data was summarized in Table 1.
The fluorescence lifetimes (τ) of the SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 were 2.53 ± 0.25 ns
and 2.62 ± 0.26 ns, respectively, bearing resemblance to that of the free DZnPc 7, which has a lifetime
of 2.92 ± 0.29 ns. A possible rational explanation was that the dendritic phthalocyanine chromophores
didn’t interact with the SWNTs, due to the dendritic structure. Meanwhile, the slight difference in
lifetimes between the SWNTs-E-DZnPc 8 and SWNTs-H-DZnPc 9 can be ascribed to the spacer
linker length. It implied that quicker the electronic exchange between the dendritic phthalocyanine and
SWNTs would occur by shortening the spacer linker. The length of spacer linker between the dendritic
phthalocyanine and SWNTs also exerted an effect on the photoinduced intramolecular electron transfer
efficiency (ΦSET) and electron transfer rate constant (KSET) of the nanoconjugates. The values of ΦSET
and KSET calculated by eqs.2-3 were shown in Table 1. The ΦSET and KSET of SWNTs-E-DZnPc 8 with
ethylenediamine showed higher fluorescence quenching efficacy and larger electron transfer rate
11

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constant than that of the SWNTs-H-DZnPc 9. This result further confirmed that the larger electronic
exchange rate and the higher electronic transfer efficiency between dendritic phthalocyanine and
SWNTs were observed with decreasing the length of spacer linker.
Φ = 1−
τ
SW NTs-E-DZnPc8 or SWNTs-H-DZnPc9
/
τ
DZnPc7
eq.2
eq.3
SET
Κ = 1/
τ
SWNTs-E-DZnPc8 or SW NTs-H-DZnPc9 −1/
τ
DZnPc7
SET
Where τSWNTs-E-DZnPc 8 or SWNTs-H-DZnPc 9 is the fluorescence lifetime of either SWNTs-E-DZnPc 8 or
SWNTs-H-DZnPc 9, while τDZnPc 7 is the fluorescence lifetime of DZnPc 7.
5
Conclusions
A novel series of dendritic phthalocyanine-single-wall carbon nanotube nanoconjugates, zinc (II)
phthalocyanine bearing poly (aryl benzyl ether) dendritic substituents covalently linked with SWNTs
through either ethylenediamine or hexamethylenediamine as the spacer linker, were synthesized and
characterized. These nanoconjugates exhibited quenching of the fluorescent emission at the Q-band of
the phthalocyanine upon excitation at 610 nm, which is due to a photoinduced intramolecular electron
transfer between the dendritc phthalocyanine and SWNTs through the spacer linker. The length of
spacer linker between the dendritic phthalocyanine and SWNTs had a marked influence on
intramolecular electron transfer efficiency and electron rate constant. The shorter the spacer linker, the
quicker the electron exchange constant and the higher electron transfer efficiency between the dendritic
phthalocyanine and SWNTs were observed. This study suggested that dendritic phthalocyanine-
single-wall carbon nanotube nanoconjugates may find potential application as biological labels.
12

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Acknowledgement
This research was supported by the National Natural Science Foundation of China (21274021,
0604007); Natural Science Foundation of Fujian, China (2011J01029) and the Science Research
2
Foundation of Ministry of Health, China (WKJ2008-2-61) and Fujian Normal University’s student
innovation programme(Sjcxcy-2012004).
References
[
1] Sinnott SB and Andrews R. Carbon Nanotubes: Synthesis, properties, and applications. Crit Rev Solid State
Mater 2001; 26: 145-72.
[
2] Odom TW, Huang JL, Kim P and Lieber CM. Structure and electronic properties of carbon nanotubes. J Phys
Chem B 2000; 104: 2794-1.
[
3] Li J, Wang YB, Qiu JD, Sun DC and Xia XH. Biocomposites of covalently linked glucose oxidase on carbon
nanotubes for glucose biosensor. Anal Bioanal Chem 2005; 383: 918-2.
[
4] Guldi DM, Rahman GMA, Prato M, Jux N, Quin S and Ford W. Single-wall carbon nanotubes as integrative
building blocks for solar-energy conversion. Angew Chem Int Ed 2005; 117: 2015-1.
[
5] Guldi DM, Rahman GMA, Quin S, Tchoul M, Ford WT, Marcaccio M, et al. Versatile coordination chemistry
towards multifunctional carbon nanotube nanohybrids. Chem-Eur J 2006; 12: 2152-1.
[
6] Baskaran D, Mays JW, Zhang XP and Bratcher MS. Carbon nanotubes with covalently linked porphyrin
antennae: photoinduced electron transfer. J Am Chem Soc 2005; 127: 6916-1.
[
7] Alvaro M, Atienzar P, de la Cruz P, Delgado JL, Troiani V, Garcı´a H, et al. Synthesis, photochemistry, and
electrochemistry of single-wall carbon nanotubes with pendent pyridyl groups and of their metal complexes with
zinc porphyrin. comparison with pyridyl-bearing fullerenes. J Am Chem Soc 2006; 128: 6626-1.
13

ACCEPTED MANUSCRIPT
[
8] Tanaka H, Yajima T, Matsumoto T, Otsuka Y and Ogawa T. Porphyrin molecular nanodevices wired using
single-walled carbon nanotubes. Adv Mater 2006; 18: 1411-1.
[
9] Ehli C, Rahman GMA, Jux N, Balbinot B, Guldi DM, Paolucci F, et al. Interactions in single-wall carbon
nanotubes/pyrene/porphyrin nanohybrids. J Am Chem Soc 2006; 128: 11222-1.
[
10] Guldi DM, Marcaccio M, Paolucci D, Paolucci F, Tagmatarchis N, Tasis D, et al. Single-wall carbon
nanotube-ferrocene nanohybrids: observing intramolecular electron transfer in functionalized SWNTs. Angew
Chem Int Ed 2003; 115: 4338-1.
[
11] Martin RB, Qu LW, Lin Y, Harruff BA, Bunker CE, Sun YP, et al. Functionalized carbon nanotubes with
tethered pyrenes: synthesis and photophysical properties. J Phys Chem B 2004; 108: 11447-1
[
12] Ballesteros B, Torre GDL, Ehli C, Rahman GMA And Torres TJ. Single-wall carbon nanotubes bearing
covalently linked phthalocyanines-photoinduced electron transfer. J Am Chem Soc 2007; 129: 5061-4.
[
13] Zhang MF, Murakami T, Ajima K, Tsuchida K, Sandanayaka ASD, et al. Fabrication of ZnPc/protein
nanohorns for double photodynamic and hyperthermic cancer phototherapy. Proc Natl Acad Sci USA 2008; 105:
1
4773-2.
[
14] Ballesteros B, Campidelli S, Torre GDL, Ehli C, Guldi DM, Prato M, et al. Synthesis, characterization and
photophysical properties of a SWNT phthalocyanine hybrid. Chem Commun 2007; 28: 2950-2.
[
15] Campidelli S, Ballesteros B, Filoramo A, Dı´az DD, Torre GDL, Torres T, et al. Facile decoration of
functionalized single-wall carbon nanotubes with phthalocyanines via “click chemistry”. J Am Chem Soc 2008;
1
30: 11503-5.
[
16] Bartelmess J, Ballesteros B, Torre GDL, Kiessling D, Campidelli S, Prato M, et al. Phthalocyanine-pyrene
conjugates: a powerful approach toward carbon nanotube solar cells. J Am Chem Soc 2010; 132: 16202-4.
14

ACCEPTED MANUSCRIPT
[
17] Chidawanyika W and Nyokong T. Characterization of amine-functionalized single-walled carbon
nanotube-low symmetry phthalocyanine conjugates. Carbon 2010; 48: 2831-6.
[
18] Saari WS, Schwering JE, Lyle PA, Smith SJ and Engelhardt EL. Cyclization-activated prodrugs. basic
carbamates of 4-hydroxyanisole. J Med Chem 1990; 33: 97-4.
[
19] Ravikumar VT. A Convenient Large Scale Synthesis Of N-Boc-ethylenediamine. Synthetic Commun 1994; 24:
1
767-2.
[
20] Peng YR, Zhang H, Wu HL, Huang BQ, Gan L and Chen Z. The synthesis and photophysical properties of
zinc (II) phthalocyanine bearing poly (aryl benzyl ether) dendritic substituents. Dyes Pigm 2010; 87: 10-4.
[
21] He DD, Zhang H, Peng YR, Ma DD, Wang YH, Yang HQ, et al. Synthesis and characterization of a novel
frétchet dendritic phthalocyanine zinc (II): Tetra-{3,5-di-[3,5-di(4-carboxylic benzyloxy) benzyloxy] benzyloxy}
Phthalocyanine Zinc(II). Chin J Org Chem 2012; 32: 1321-6.
[
22] Yang ZL, Chen HZ, Cao L, Li HY, Wang M. Synthesis and photoconductivity study of carbon nanotube bonded
by tetrasubstituted amino manganese phthalocyanine. Mater Sci Eng. B 2004; 106: 73-2.
[
23] Bahr JL, Yang JP, Kosynkin DV, Bronikowski MJ, Smalley RE, and Tour JM. Functionalization of carbon
nanotubes by electrochemical reduction of aryl diazonium salts: a bucky paper electrode. J Am Chem Soc 2001; 123:
6
536-3.
[
24] Dillon EP, Crouse CA and Barron AR. Synthesis, characterization, and carbon dioxide adsorption of
covalently attached polyethyleneimine-functionalized single-wall carbon nanotubes. Acs Nano 2008; 2: 156-5.
[
25] Dresselhaus MS, Dresselhaus G and Jorio A. Raman spectroscopy of carbon nanotubes in 1997 and 2007. J
Phys Chem C 2007; 111: 17887-1.
[
26] Khanh HLH, Rivier L, Jousselme B, Jegou P, Filoramo A and Campidelli S. Zn-porphyrin /zn-phthalocyanine
dendron for SWNT functionalisation. Chem Commun 2010; 46: 8731-2.
15

ACCEPTED MANUSCRIPT
[
27] Campidelli S, Ballesteros B, Filoramo A, Dı´az DD, Torre GDL, Torres T, et al. Facile decoration of
functionalized single-wall carbon nanotubes with phthalocyanines via “click chemistry”. J Am Chem Soc 2008;
1
30: 11503-4.
[
28] Campidelli S, Sooambar C, Diz EL, Ehli C, Guldi DM and Prato M. Dendrimer-functionalized single-wall
carbon nanotubes: synthesis, characterization, and photoinduced electron transfer. J Am Chem Soc 2006; 128:
1
2544-6.
[
29] Fery-Forgues S and Lavabre D. Are fluorescence quantum yields so tricky to measure? A demonstration using
familiar stationery products. J Chem Educ 1999; 76: 1260-1.
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Figure 1 TEM images of SWNTs-COOH (a), SWNTs-E-DZnPc8 (b) and SWNTs-H-DZnPc9 (c)
Figure 2 IR spectra of SWNTs-COOH, DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9
Figure 3 Raman Spectra of SWNTs-COOH, DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9
Figure 4 TGA curves of SWNTs-COOH, DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9
Figure 5 UV/Vis of SWNTs-COOH, DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 in DMF at room
-5
temperature (C SWNTs-COOH, DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 = 2×10 mol/L)
Figure 6 Steady-state fluorescence spectra of DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 in DMF at
room temperature (λex = 610 nm). Curves for SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 have been
-5
amplified by a factor of 20. (C DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 = 2×10 mol/L)
Figure 7 Time-resolved fluorescence spectra of DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 in DMF
-5
(λex= 405 nm, C DZnPc7, SWNTs-E-DZnPc8 and SWNTs-H-DZnPc9 = 2×10 mol/L)
Scheme 1 The scheme of synthetic route for dendritic zinc phthalocyanine-SWNTs nanoconjugates

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Table 1
Photophysical properties of SWNTs-E-DZnPc8, SWNTs-H-DZnpc9 in DMF
a
-1
Complexes
Absorption
Emission
Ф
F
τ
s
/ns
Ф
SET
K
SET(s )
λmax/nm
λmax/nm
DZnPc7
678
709
0.10
0.14
0.05
2.92
2.53
2.62
-
-
7
SWNTs-E-DZnPc8
SWNTs-H-DZnPc9
682
683
688
688
0.13
0.10
5.3×10
3.9×10
7
a
F
Znpc䟉Ф =0.30䟊as the standard.

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Figure 1

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Supporting Information
Single-wall Carbon Nanotubes Covalently Linked
with Zinc (
) Phthalocyanine Bearing Poly(aryl
benzyl ether) Dendritic Substituents䟛Synthesis䟍
Characterization and Photoinduced Electron
Transfer
1
∗ 1
2
1
Dandan He , Yiru Peng , Hongqin Yang , Dongdong Ma , Yuhua
2
1
Wang 䟍Kuizhi Chen , Pingping Lin, Kuizhi Chen
1
College of Chemistry and Engineering, Fujian Provincial Key Laboratory
of Polymer Materials, Fujian Normal University, Fuzhou 350007, China
2
Key Lab of Optoelectronic Science and Technology for Medicine of Ministry of
Education, Fujian Normal University, Fuzhou 350007, China
∗
Corresponding author. Tel.: + 86 591 8346 5225.
E-mail address: yirupeng@fjnu.edu.cn (Y. Peng).