A systematic study of electrochemical and spectral properties for the electronic interactions in porphyrin-triphenylamine conjugates

Article abstract of DOI:10.1002/ejic.201101033

A series of mono-, di-, tri-, and tetra-triphenylamine (TPA)-substituted porphyrinatozinc complexes have been synthesized to investigate their spectral and electrochemical properties. The varied shapes of absorption spectra of porphyrin-triphenylamine (Po

Full text of DOI:10.1002/ejic.201101033

FULL PAPER
DOI: 10.1002/ejic.201101033
A Systematic Study of Electrochemical and Spectral Properties for the
Electronic Interactions in Porphyrin–Triphenylamine Conjugates
Chih-Yen Huang,[a] Chao-Yen Hsu,[a] Luo-Yi Yang,[a] Chia-Jung Lee,[a] Te-Fang Yang,[a]
Chia-Chan Hsu,[a] Chung-Hsiu Ke,[a] and Yuhlong Oliver Su*[a,b]
Keywords: Electrochemistry / Electron transfer / Charge transfer / Energy transfer / Luminescence / Zinc / Porphyrinoids /
Antenna effect
A series of mono-, di-, tri-, and tetra-triphenylamine (TPA)-
when more TPA moieties were linked. Cyclic voltammetry
substituted porphyrinatozinc complexes have been synthe- and spectroelectrochemical methods revealed the redox
sized to investigate their spectral and electrochemical prop-
erties. The varied shapes of absorption spectra of porphyrin–
triphenylamine (Por–TPA) conjugates in comparison with tet-
ramesitylporphyrinatozinc (ZnTMP) indicate that there are
strong interactions between porphyrin and TPA moieties. In
general, the electron-donating capability of a substituent on
properties of Por–TPA conjugates. Axial ligation of por-
phyrinatozinc with N-methylimidazole was useful in differ-
entiating the oxidation site of Por–TPA conjugates. The first
one-electron oxidations of these conjugates are at the por-
phyrin ring. The charge-transfer bands present in the near-
IR region in the absorption spectra of Por–TPA radical cations
TPA and the number of TPA derivatives that bond with por- are evidence of an electronic interaction between porphyrin
phyrin would cause Soret band broadening and intensifi-
cation of the Q(0,0) band. Due to the antenna effect of these
conjugates, the fluorescence quantum yields were enhanced
and TPA. The electron-donating strength of the TPA group
and the symmetry of the Por–TPA conjugate affect the inten-
sity of the charge-transfer band.
the absorption spectrum as the porphyrin ring was oxid-
ized. These phenomena indicated that there were strong
electronic interactions between the porphyrin core and TPA
moieties.
Introduction
Porphyrin molecules have unique electrochemical and
photophysical properties, which can be easily controlled by
functionalization with specific groups at the meso and β
Recently, we published a spectral and electrochemical in-
positions.[1] Recently, the hybridization of porphyrins and vestigation of porphyrin–triphenylamine dendrimers[6] be-
photoelectronic molecules such as triphenylamine (TPA) cause of their interesting behavior in spectroscopy and elec-
has attracted much attention.[2–6] TPA-based derivatives are trochemistry. It is worth studying how each TPA group in-
widely investigated for the application of dye-sensitized so- teracts with porphyrinatozinc and to establish the knowl-
lar cells,[7] organic light-emitting diodes,[8] and electro- edge of the electronic properties of the Por–TPA conjugate.
chromic polymers.[9] Cheng’s and Yeh’s groups reported the Thus the mono-, di-, tri-, and tetra-TPA-substituted Por–
spectral and electrochemical properties of porphyrin–tri- TPA conjugates were synthesized. Early work on the elec-
phenylamine hybrid conjugates.[2–4] Both of their studies tronic effects of unsymmetrical phenyl substitution on the
showed an obvious bathochromic shift in the Soret and Q π-electron system of a porphyrin ring has been carried out
bands; the potential shift of porphyrin-ring oxidation and by Walker and co-workers.[10] As shown in Figure 1, we re-
the charge-transfer band appeared in the near-IR region of port here a series of Por–TPA conjugates bound to one to
four TPA derivatives and with different substituents at the
para position of TPA in an investigation of the electronic
interactions between a porphyrin core and the TPA moiety.
[a] Department of Applied Chemistry, National Chi Nan
Due to the solubility problem of a tetrakis(TPA-NO2)-sub-
stituted porphyrin, conjugate 4 with four TPA-Cl was used
instead. In this work, we have studied two kinds of effects
on the spectral and electrochemical properties of Por–TPA
conjugates. The first is the number of TPA derivatives
bound with porphyrinatozinc, and the second is the func-
tional group substituted at the para position of TPA.
University,
1, University Rd., Puli, Nantou County 545, Taiwan
Fax: +886-49-2917956
E-mail: yosu@ncnu.edu.tw
[b] Department of Materials Science and Engineering, National
Chung Hsing University,
250 Kuo Kuang Rd., Taichung 402, Taiwan
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201101033.
1038
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 1038–1047

Electronic Interactions in Porphyrin–Triphenylamine Conjugates
Figure 2. Absorption spectra of ZnTMP and 13–16 in CH2Cl2.
Cyan: ZnTMP, black: 13, red: 14, blue: 15, green: 16.
shapes of spectra relative to ZnTMP. As the number of
bound TPA-OCH3 groups increased from one to four, the
absorption spectra exhibited an intense specific absorption
of TPA at around 300 nm. On the other hand, the Soret
band absorption decreased in its molar extinction coeffi-
cient (ε) and broadened. Both Q bands exhibited bathoch-
romic shifts and a significant increase in the ε of Q(0,0)
band. These observations indicate that there are strong elec-
Figure 1. Structures of ZnTMP and Por–TPA conjugates.
Results and Discussion
Figure 2 shows the absorption spectra of ZnTMP and tronic interactions between TPA-OCH3 and porphyrinato-
Por–TPA conjugates with different numbers of bound TPA- zinc. The absorption maxima (λabs) and molar extinction
OCH3 groups. The mono- to tetra(TPA-OCH3)-substituted coefficients of ZnTMP and Por–TPA conjugates are sum-
porphyrinatozinc complexes 13–16 exhibit very different marized in Table 1. In general, more TPA bound with por-
Table 1. Absorption maximum (λabs) [nm] with molar extinction coefficient (ε) [104 mol–1 dmcm–1] in parenthesis, emission maximum
(λem) [nm], and quantum yields of ZnTMP and Por–TPA conjugates in CH2Cl2.
Absorption
Q(0,1)
Emission
Antenna effect
[a]
[c]
Porphyrins
TPA band
Soret band
Q(0,0)
εQ(0,0)/εQ(0,1)
λem
Quantum
λem
Emission
yield[b]
peak area[c,d]
ZnTMP
–
421 (74.82)
550 (2.63)
587 (0.25)
0.10
592, 644
0.044
–
–
[e]
1
2
3
4
–
422 (45.03)
423 (25.93)
426 (43.63)
436 (18.80)
550 (1.86)
551 (1.60)
551 (2.19)
555 (1.65)
589 (0.25)
593 (0.49)
593 (0.65)
597 (1.03)
0.13
0.31
0.30
0.62
597, 646
599, 647
601, 650
614
0.021
0.021
0.028
0.093
598, 648
601, 650
601, 650
621
0.07ϫ105
0.05ϫ105
0.24ϫ105
1.62ϫ105
[e]
–
[e]
–
311 (7.79)
5
6
7
8
305 (3.68)
307 (5.76)
306 (7.77)
305 (8.71)[f]
422 (33.79)
424 (29.07)
432 (23.30)
438 (18.60)[f]
551 (2.34)
552 (2.56)
554 (2.47)
555 (2.24)[f]
588 (0.44)
595 (0.87)
596 (1.31)
599 (1.76)[f]
0.19
0.34
0.53
0.79
600, 648
606, 651
613, 653
618
0.060
0.077
0.081
0.100
601, 649
602, 653
606, 655
616
0.61ϫ105
0.98ϫ105
1.20ϫ105
1.60ϫ105
9
308 (3.90)
307 (4.86)
305 (6.67)
305 (9.45)[f]
422 (37.64)
423 (19.05)
429 (13.50)
442 (16.60)[f]
552 (2.51)
553 (2.10)
555 (1.85)
557 (2.15)[f]
592 (0.51)
595 (0.89)
599 (1.19)
602 (1.99)[f]
0.20
0.42
0.64
0.93
602, 648
609, 652
617
0.070
0.088
0.091
0.100
601, 649
603, 652
619
0.57ϫ105
0.96ϫ105
1.70ϫ105
1.99ϫ105
10
11
12
625
624
13
14
15
16
307 (3.93)
305 (5.90)
302 (5.02)
301 (6.98)[g]
421 (37.16)
420 (23.04)
425 (14.20)
445 (12.30)[g]
553 (2.64)
554 (2.71)
556 (1.67)
558 (1.59)[g]
593 (0.59)
597 (1.34)
600 (1.06)
604 (1.70)[g]
0.22
0.49
0.63
1.07
605, 650
613
0.059
0.078
601, 649
614
622
0.66ϫ105
0.61ϫ105
1.22ϫ105
3.04ϫ105
621
0.088
636[g]
0.130[g]
637
[a] ZnTMP and all the Por–TPA conjugates were excited at the Soret band. [b] Using H2TPP as standard. The quantum yield of H2TPP
was set to 0.11[13]. [c] The Por–TPA conjugates were excited at the TPA moiety. In the spectra of conjugates 4–16, the emission peak was
overlapped with excitation overtone. [d] Plotting fluorescence spectra in the form of intensity versus wavenumber. The emission peak area
was obtained by integration from 17857 to 12500 cm–1 (560 to 800 nm). For conjugates 1–3, the areas were integrated from 17857 to
13888 cm–1 (560 to 720 nm). [e] The absorption maximum of TPA-NO2 is at 417 nm in CH2Cl2. [f] Data from the literature[2]. [g] Data
from the literature[6]
.
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1039

Y. O. Su et al.
FULL PAPER
phyrinatozinc further causes a redshift of both Soret and Q result of π-conjugation expansion. This is consistent with
bands, an increase in ε value of the TPA and Q(0,0) bands, what we inferred from the absorption spectra. On the other
and a decrease in the ε value of the Soret band. For exam- hand, the quantum efficiency of conjugates was measured
ple, the Q(0,0) band of tetrakis(TPA-OCH3) porphyrinato- by using H2TPP as standard in which the quantum yield of
zinc 16 is redshifted by 11 and 17 nm relative to por- H2TPP was set to 0.11.[13] Values obtained for Por–TPA
phyrinatozinc 13 and ZnTMP, respectively. The enhance- conjugates are listed in Table 1. An enhancement in quan-
ment in the (εQ(0,0)/εQ(0,1)) ratio of 16 is about 5 and 11 tum efficiency was observed when TPA derivatives were
times more than that of 13 and ZnTMP, respectively. We bound to the zinc complex except for conjugates with
also found that the substituent effect at the TPA moieties is strong electron-withdrawing nitro groups. Cheng’s group
relatively small. The Q(0,0) band of the tetrakis(TPA- and ours have reported the antenna effect of tri-
OCH3) porphyrinatozinc 16 is redshifted only by 5 nm rela- phenylamine-bound porphyrinatozinc before.[2,6] In this
tive to the tetrakis(TPA)-substituted zinc complex 8. Al- study, we also examine the antenna effect of the Por–TPA
though the nitro group is strongly electron-withdrawing, conjugates by exciting at their corresponding TPA moieties
zinc complexes 1–3 bound with TPA-NO2 group still exhi- (Figure S15 in the Supporting Information). All the fluores-
bit redshifts of Q bands relative to ZnTMP. Apparently, cence spectra of these conjugates are similar to those emit-
these phenomena suggest that the number of TPA deriva- ted by porphyrin with Soret-band excitation, thereby indi-
tives bound with porphyrinatozinc is the major effect on cating an intramolecular energy transfer from TPA to por-
the ground-state electronic configuration of the porphyrin phyrinatozinc. The relaxation from the S1 of porphyrin to
as the result of π-conjugation expansion. The strongly en- S0 was then observed. The λem obtained from TPA exci-
hanced Q(0,0) band should be due to the enlarged energy tation are listed in Table 1. In the molecular structures of
difference between a2u and a1u orbitals of porphyrin. From Por–TPA conjugates, the TPA moieties act as antennas to
the four-orbital-model theory,[11] TPA derivatives bound at absorb radiation. Consequently, the fluorescence intensity
the meso position of the porphyrin ring can interact with was increased as more TPA bonded with porphyrinatozinc.
the a2u orbital of porphyrinatozinc and the strong electron- This phenomenon is reflected in the increased emission
donating group, then raise the energy of the a2u orbital.[12]
The fluorescence spectra and emission maximum (λem
peak area (Table 1). The typical emission peak of TPA can
be observed slightly in the spectra of tri-TPA-bound conju-
)
of Por–TPA conjugates are shown and listed in Figure 3 gates only. At its simplest, it may due to the low symmetry
and Table 1. In comparison with ZnTMP, the emission of tri-TPA-bound conjugates. Further confirmation of the
maximum of tetra-TPA-bonded Por–TPA conjugates 4, 8, antenna effect was performed by recording the excitation
12, and 16 were largely redshifted by 22, 26, 33, and 44 nm, profiles of Por–TPA conjugates (Figures S16 and S17 in the
respectively.
Supporting Information).
Electrochemical Properties
Cyclic voltammetry (CV) and spectroelectrochemistry
were used to investigate the electrochemical behavior of
Por–TPA conjugates. It can be expected that there would
be multiple oxidations, including two steps of one-electron
ring oxidation of porphyrinatozinc and the oxidation of the
nitrogen atom of TPA in the cyclic voltammograms of Por–
TPA conjugates in which several TPA groups were bound
with porphyrinatozinc. Figure 4 shows the CVs of ZnTMP
and zinc complexes 13–16 with different numbers of TPA-
OCH3. As only one TPA-OCH3 group is bound to por-
phyrinatozinc, the CV of 13 exhibits three redox couples
in oxidation. Subsequently, as more TPA-OCH3 groups are
bonded, 14–16 exhibit multiple and overlapping oxidation
Figure 3. Normalized fluorescence spectra of Por–TPA conjugates
in CH2Cl2. All of the conjugates were excited at the Soret band. waves in their CVs. It is interesting to study the electro-
The black, red, blue, and green lines indicate mono-, di-, tri-, and
chemical behavior of each redox in the CVs of Por–TPA
tetra(TPA-X)-substituted conjugates, respectively. (a) TPA-NO2
conjugates even though the CVs become more complex as
(green line: TPA-Cl); (b) TPA; (c) TPA-CH3; (d) TPA-OCH3-sub-
the number of TPA increases. Hence, in the following dis-
stituted Por–TPA conjugates.
cussion, we focus on the effect of the first-electron oxidation
(Ox1) of conjugates after TPA derivatives were bound. The
However, for mono-TPA-bonded conjugates 1, 5, 9, and electrochemical data obtained from CV are summarized in
13, the redshifts in λem were less than 13 nm. It again dem- Table 2. As more TPA groups bonded with porphyrinato-
onstrated that the number of bound TPA has a major effect zinc, the conjugates were easier to oxidize, as reflected in
on the electronic configuration of porphyrinatozinc as the the cathodic shift in their onset potentials (Eonset). Basically,
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Eur. J. Inorg. Chem. 2012, 1038–1047

Electronic Interactions in Porphyrin–Triphenylamine Conjugates
TPA is an electron-donating group. Conjugate 1 and 2 show
In our previous study of the porphyrinatozinc core den-
almost no difference in Eonset relative to ZnTMP. The re- drimers, we were able to deconvolute the overlapping CV
sults indicate a diminished electronic interaction by the ni- by introducing N-methylimidazole (N-MeIm) as an axial li-
tro groups bound at TPA, whereas conjugate 16 with four gand.[6] Imidazole is a strong nitrogenous base that, ligated
TPA-OCH3 exhibits a large cathodic shift of 0.19 V. Obvi- with porphyrinatozinc, would cause a cathodic shift in the
ously, the Eonset values of these conjugates are dominated potential for first porphyrinatozinc oxidation.[14] Thus, N-
by electron-donating capability.
MeIm is useful to differentiate the oxidation site of Por–
TPA conjugates. After ligating with electron-rich N-MeIm,
the CVs of Por–TPA conjugates all exhibit a cathodic shift
in the first oxidation potential (Ox1Ј in Table 2; Figures S22
and S23 in the Supporting Information). The observation
indicates that the Ox1 of four-coordinate Por–TPA conju-
gates belongs to the first ring oxidation of porphyrins. For
example, Figure 5 is the CV of 13 in the presence of N-
MeIm. As N-MeIm is added to the solution, the half-wave
potentials exhibit a cathodic shift for Ox1 and an anodic
shift for Ox3. Ox2, however, remains unchanged in poten-
tial. These observations indicate that Ox1 and Ox3 are due
to the porphyrin-ring oxidations and that Ox2 is the oxi-
dation at TPA. The first half-wave potentials of N-MeIm-
ligated TPA–Por conjugates (Ox1Ј) are summarized in
Table 2.
Figure 4. Cyclic voltammograms of (a) ZnTMP, (b) 13, (c) 14, (d)
15, and (e) 16 in CH2Cl2 containing 0.1 m tetra-n-butylammonium
perchlorate (TBAP). Scan rate: 0.1 Vs–1. Molar concentrations of
compounds: 1.0ϫ10–3 m.
Table 2. Half-wave potentials [E1/2 versus Ag/AgCl (saturated)][a]
and peak potentials (Ep) of ZnTMP and 1–16.
Ox5
Ox4
Ox3
–
Ox2
Ox1
Eonset Ox1Ј[b]
ZnTMP
–
–
–
–
–
–
–
–
–
+1.12 +0.80 +0.71 +0.63
Figure 5. Cyclic voltammograms of Por–TPA conjugate 13 in
CH2Cl2 containing 0.1 m TBAP. Scan rate: 0.1 Vs–1. Molar concen-
tration of 13 is 1.0ϫ10–3 m; [N-MeIm]: (a) 0, (b) 2.5ϫ10–4, (c)
5.0ϫ10–4; (d) 7.5ϫ10–4, and (e) 1.0ϫ10–3 m.
1
2
3
4
+1.66 +1.14 +0.82 +0.72 +0.72
+1.46[e] +1.13 +0.83 +0.72 +0.76
–
+1.61[e] +0.84 +0.67 +0.80[e]
+1.51[e] +1.32[d] +0.94 +0.74 +0.65 +0.66
5
6
7
8
–
–
–
–
–
–
–
–
+1.36[e] +1.07 +0.79 +0.68 +0.65
+1.29[e] +0.91 +0.73 +0.66 +0.60
+1.38[d,e]+0.92 +0.73 +0.65 +0.59
+1.30[d,e]+0.84 +0.71 +0.63 +0.59
The effects of the substituent at TPA on the oxidation
potential of Por–TPA conjugates were also examined by
CV. In Figure 6, the CVs of mono-TPA-bound conjugates
1, 5, 9, and 13 clearly show three redox couples in their
oxidations, including two electrons removed from the por-
phyrin ring and one electron removed from the nitrogen
atom of TPA derivatives. For the above compounds, the
first oxidation potentials are at +0.82, +0.79, +0.75, and
+0.74 V, respectively. Addition of N-MeIm causes the po-
tential shifts to +0.72, +0.65, +0.64, and +0.60 V, respec-
tively. It is thus inferred that the first oxidation sites of Por–
9
–
+1.79[e] +1.25 +1.00 +0.75 +0.66 +0.64
10
11
12
+1.70[e] +1.26 +1.09 +0.95 +0.70 +0.63 +0.60
–
+1.33 +1.09[d] +0.87 +0.71 +0.61 +0.58
+1.68[e] +1.33 +1.08[d] +0.76 +0.65 +0.60 +0.57
13
14
15
16
–
+1.44[e] +1.20 +0.88 +0.74 +0.64 +0.60
+1.47[e] +1.23 +0.93 +0.82 +0.68 +0.63 +0.58
+1.43[e] +0.92[c] +0.83[c] +0.70[c] +0.59 +0.57
+1.35[e] +0.96 +0.87[d] +0.69[c] +0.62[c] +0.52 +0.50
–
[a] E1/2 of Fc+/Fc is +0.54 V versus Ag/AgCl (saturated). [b] The
E1/2 of Ox1 of five-coordinate porphyrinatozinc. [c] Estimated half-
wave potential by deconvoluting the overlapped CV. [d] Multiple
electron transfer involved. [e] Peak potential of an irreversible wave. TPA conjugates 1, 5, 9, and 13 are all at the porphyrin ring.
Eur. J. Inorg. Chem. 2012, 1038–1047
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Y. O. Su et al.
FULL PAPER
The second oxidation potentials of compounds 5, 9, and the nature of substituent at the para positions of TPA di-
13 remain unchanged upon N-MeIm addition and are thus rectly affects the oxidation potential of TPA more than that
assigned as their respective TPA oxidation. However, the of porphyrinatozinc. Electron-donating methyl and meth-
second oxidation of compound 1 shifts concurrently to a oxy groups of conjugates 9 and 13 cause both the first ring
more anodic potential, the third oxidation of which remains oxidation of porphyrin and nitrogen atom to be easier to
unchanged. Thus, the Ox1 and Ox2 of conjugate 1 are at- oxidize than conjugate 5, whereas the strong electron-with-
tributed to the first and second porphyrin-ring oxidations. drawing nitro group of conjugate 1 has the opposite effect.
Namely, the strong electron-withdrawing nitro groups at-
tached to the para positions of TPA cause the TPA group
to be more difficult to oxidize than porphyrin ring. Clearly,
In the studies of Por–TPA conjugates, we found that both
substituent effect and the number of bound TPA derivatives
significantly affect the oxidation potentials of TPA and the
porphyrin ring. Generally, the porphyrinatozinc ring is oxi-
dized first, and the electron-donating substituents at the
para position of TPA cause a cathodic shift in potential of
Ox1, whereas electron-withdrawing groups cause the oppo-
site effect. Furthermore, since triphenylamine itself is an
electron-donating group, the presence of methoxy groups
will enhance the effect on oxidation potential in the same
direction. However, the presence of electron-withdrawing
groups such as Cl and NO2 will decrease the electron-do-
nating capability of triphenylamine. For example, conjugate
4 is harder to oxidize by 0.06 V than conjugate 8, but it is
easier to oxidize than ZnTMP (Table 2).
Based on the results of cyclic voltammetry and absorp-
tion spectra discussed above, the Por–TPA conjugate 16,
which has four TPA-OCH3 groups bound to porphyrinatoz-
inc, would have the strongest electrochemical interaction
between the porphyrinatozinc core and the TPA groups.
Figure 6. Cyclic voltammograms of mono-substituted Por–TPA
conjugates (a) 1, (b) 5, (c) 9, and (d) 13 in CH2Cl2 containing 0.1 m
TBAP. Scan rate: 0.1 Vs–1. Molar concentrations of conjugates:
1.0ϫ10–3 m.
Figure 7. Spectral changes of (a) 13, (b) 14, (c) 15, and (d) 16 in CH2Cl2 containing 0.1 m TBAP at various applied potentials.
1042 Eur. J. Inorg. Chem. 2012, 1038–1047
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Electronic Interactions in Porphyrin–Triphenylamine Conjugates
Spectroelectrochemistry
mote the charge-transfer process, and methyl groups or hy-
drogen atoms have less effect on it. On the other hand, the
strong electron-withdrawing nitro groups would pull the
electron cloud of the nitrogen atom of TPA away from the
porphyrin ring and make it more difficult for charge trans-
fer to proceed.
The studies of electron interaction between TPA deriva-
tives and porphyrinatozinc were carried out by UV/Vis/
NIR spectroelectrochemistry. The spectral changes of 13–16
upon applied potentials to form their corresponding radical
cation are shown in Figure 7. In Figure 7A, the diminishing
Soret band at 421 nm and the formation of a specific ab-
sorption band of the porphyrin radical cation at 500–
700 nm indicate that the porphyrin ring is oxidized. This
result is consistent with that inferred from cyclic voltamme-
try. During the process of 13 oxidation to 13+·, the ab-
sorbance of TPA-OCH3 at 307 nm decreased slightly. New
bands at 754 and 1298 nm were formed and are assigned as
the specific absorption of triarylamine radical cation and
the intramolecular charge transfer from TPA-OCH3 moiety
to porphyrinatozinc, respectively.[3,6] The porphyrin ring
was oxidized first and the Por–TPA conjugate thus became
an electron donor–acceptor complex in which the electron-
rich TPA-OCH3 moiety would transfer its electron cloud to
the porphyrin ring, which lacks an electron after oxidation.
The new charge-transfer band at the NIR region is evidence
of the electronic interaction between the porphyrinatozinc
radical cation and the TPA-OCH3 moiety. Similar phenom-
ena were also observed in the absorption spectra of conju-
gates 14–16 upon oxidation (Figure 7, B–D). The spectro-
scopic data of charge-transfer bands of the radical cation
spectra of Por–TPA conjugates are summarized in Table 3.
In the radical cation spectra of mono- and bis(TPA-NO2)-
bound zinc complexes 1 and 2, there are no charge-transfer
bands in the region of 900–2200 nm. Apparently, the pres-
ence of strong electron-donating methoxy groups can pro-
The oscillator strengths[15] (f) of charge-transfer bands of
that tri-TPA-substituted conjugates are much less than
those of di- and tetra-TPA-substituted conjugates in their
respective radical cation forms. These results may be attrib-
uted to their low symmetry. Conjugate 4 has a high f value
of 0.243 even though chlorine possesses electron-with-
drawing property. This could interpret that the number of
bonded TPA groups is the major effect on the electronic
properties of porphyrinatozinc again.
Conclusion
A series of Por–TPA conjugates have been synthesized
and characterized by spectral and electrochemical methods.
The absorption spectra of Por–TPA conjugates exhibit
broadening of Soret band, intensifying of the Q(0,0) band,
and redshifting of both Soret and Q bands as more TPA
derivatives bond to porphyrinatozinc. These phenomena
indicate the strong electronic interaction between porphyrin
and triphenylamine moieties. In the emission spectroscopy
study, the intramolecular energy transfer was found in all
Por–TPA conjugates. When TPA moieties were excited, they
would transfer energy to the porphyrinatozinc core from
which fluorescence occurred. Due to the antenna effect
found in these conjugates, an enhancement in quantum effi-
ciency can be observed as the number of TPA derivatives
increases. In cyclic voltammetry, more TPA groups in the
Por–TPA conjugate cause more oxidation centers to be
present in the molecular structure. We have characterized
the Ox1 of each Por–TPA conjugate as the oxidation site.
The porphyrin-ring oxidation has been identified by utiliz-
ing the N-MeIm ligation effect and spectroelectrochemical
methods. In the radical cation absorption spectra of Por–
TPA conjugates, the oscillator strength describes the inten-
sity of charge-transfer bands in the NIR region. The Por–
TPA conjugate that has a higher symmetry, more bound
TPA groups, and stronger electron-donating at the para po-
sition of TPA would have a more intense charge-transfer
band, which accounts for a stronger interaction.
Table 3. Absorption maximum (λabs) [nm] with molar extinction
coefficients (ε) [mol–1 dm3cm–1], full width at half-maximum height
(fwhm) [cm–1], and oscillator strength (f)[a] of the radical cation
spectra of Por–TPA conjugates in CH2Cl2.
meso-Substituents
λabs
ε
fwhm
f[a]
[b]
[b]
[b]
[b]
1
2
3
4
(TPA-NO2)1
(TPA-NO2)2
(TPA-NO2)3
(TPA-Cl)4
–
–
–
–
–
–
–
–
[b]
[b]
[b]
[b]
994
1226
6196
23435
3818
3131
0.077
0.243
5
6
7
8
(TPA)1
(TPA)2
(TPA)3
(TPA)4
1254
1262
1190
1243
5086
10530
11044
24063
3680
3537
2398
3137
0.045
0.102
0.077
0.240
9
(TPA-CH3)1
(TPA-CH3)2
(TPA-CH3)3
(TPA-CH3)4
1338
1290
1264
1296
6757
15534
8459
2910
2753
2984
3673
0.057
0.145
0.076
0.340
10
11
12
Experimental Section
30093
General: 1H and 13C NMR spectra were obtained with a Bruker
Avance-III 300 spectrometer. A Varian Cary-50 scanning UV/Vis
spectrometer was used to determine extinction coefficients of Por–
TPA conjugates and to obtain absorption spectra with a 1 cm cu-
vette. Mass spectra were obtained with Applied Biosystem Voyager-
DETM Pro spectrometer. Emission spectra, excitation profiles, and
fluorescence quantum yield measurements were completed with a
Varian Cary Eclipse spectrometer. For electrochemical studies, a
CHI 700A electroanalytical workstation was used for cyclic voltam-
metry and conducted with a three-electrode cell. Glassy carbon
13
14
15
16
(TPA-OCH3)1
(TPA-OCH3)2
(TPA-OCH3)3
(TPA-OCH3)4
1298
1350
1610
1418
7766
18252
9524
5681
2877
4116
4715
0.106
0.173
0.116
0.530
40107
[a] Taken from the literature[15]
. Oscillator strength (f) =
4.319ϫ10–9 A/n, for which A = integrated area of peak and n =
refractive index of CH2Cl2. Using the plot of ε versus cm–1 to ob-
tain the integrated area (A) of each absorption peak in the spec-
trum. [b] No absorption band present in the region of 900–
2200 nm.
Eur. J. Inorg. Chem. 2012, 1038–1047
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1043

Y. O. Su et al.
FULL PAPER
electrode (area: 0.07 cm2) was used as working electrode. The auxil-
iary and reference electrodes were platinum wire and Ag/AgCl
(aqueous satd. KCl), respectively. Spectroelectrochemistry was per-
formed with JASCO V-570 UV/Vis/NIR spectrometer and Bio-
analytical System Model SP-2 potentiostat. Platinum gauze, plati-
num wire, and Ag/AgCl (aqueous satd. KCl) were used as working,
auxiliary, and reference electrodes, respectively, in a spectroelectro-
chemical cell with an 1 mm optical path length.
General Procedures in Synthesis of Por–TPA Conjugates: The syn-
thetic routes of Por–TPA are shown in Scheme 1. Generally, the
amino compound and the corresponding iodo compound were
added into a reaction vessel that contained copper powder, potas-
sium carbonate, 18-crown-6, and o-dichlorobenzene (2–3 mL). The
reaction mixture was heated to reflux with stirring for 24 h under
N2 atmosphere. After the reaction was complete, the mixture was
cooled to room temperature, then filtered and washed with CH2Cl2.
The filtrate was passed through a silica gel column. In general,
hexane was used as the first eluent to elute o-dichlorobenzene.
Next, hexane/CH2Cl2 mixed solvent was used to obtain each target
compound. For tri-TPA-substituted Por–TPA conjugates, CH2Cl2/
EA was necessary to use as final eluent. Nitro-containing Por–TPA
conjugates were synthesized by treating 4-fluoronitrobenzene with
the corresponding amino compound in the presence of cesium fluo-
ride (CsF) in DMSO (5 mL). The reaction was performed at 140 °C
for 24 h under N2. The reaction mixture was cooled, poured into
chilled water, and stirred for 2 h with an ice bath. The crude prod-
uct was then collected by filtration and dried in vacuo. Further
purifications are described individually in the following sections.
Materials: Tetramesitylporphyrinatozinc (ZnTMP),[16] 5-(4-amino-
phenyl)-10,15,20-trimesitylporphyrinatozinc [Zn(AP)(mesityl)3P],[17]
5,15-bis(4-aminophenyl)-10,20-dimesitylporphyrinatozinc
[Zn-
(AP)2(mesityl)2P],[18] and tetrakis(4-aminophenyl)porphyrinatozinc
(ZnTAPP)[19] were synthesized according to literature methods, the
metalation was performed with zinc acetate dihydrate in CH2Cl2/
CH3OH. N,N-Bis(4-methoxyphenyl)phenylamine (TPA-OCH3)
was obtained from the literature method.[20] N,N-Bis(4-nitrophen-
yl)phenylamine (TPA-NO2) was synthesized by modifying the lit-
erature method,[21] in which 3,4-dimethylaniline was replaced by
aniline. Except for nitro-containing compounds, N,N-bis(4-meth-
ylphenyl)phenylamine
(TPA-CH3),[22]
N,N-bis(4-chlorophen-
yl)phenylamine (TPA-Cl),[23] and Por–TPA derivatives were ob-
tained by means of the Ullmann reaction.[24] Other chemicals were
all commercially available. Organic solvents used in electrochemical
studies were dried and distilled before use. TBAP was recrystallized
twice from ethyl acetate (EA) and dried before use.
5,10,15-Tris(4-aminophenyl)-20-mesitylporphyrinatozinc [Zn(AP)3-
(mesityl)P]: The precursor 5-mesityl-10,15,20-tris(4-nitrophenyl)-
porphyrin free base was obtained from the condensation of mesityl-
aldehyde (0.37 g, 2.50 mmol) and 4-nitrobenzaldehyde (1.14 g,
7.50 mmol) with pyrrole (0.70 mL, 10.00 mmol) by using the same
Scheme 1. Synthetic routes for Por–TPA conjugates.
1044
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 1038–1047

Electronic Interactions in Porphyrin–Triphenylamine Conjugates
reaction conditions of H2TMP.[16] The crude solid first underwent
soxhlet extraction with MeOH to wash the black substance away.
Then acetone was used to wash H2TMP, mono- and di-ni-
trophenyl-substituted porphyrin free base out of the crude solid.
The tri- and tetra-nitrophenylporphyrin free bases remained in the
thimble. These nitrophenylporphyrin mixtures were then reduced
directly by using stannous chloride.[19] The resulting mixtures of
aminophenylporphyrins were dissolved in CH2Cl2 and chromato-
graphed by silica gel column with CH2Cl2/EA mixed solvent as
eluent. 5,10,15-Tris(4-aminophenyl)-20-mesitylporphyrin free base
[H2(AP)3(mesityl)P] was obtained; yield 0.23 g, 13%. Zn(AP)3(mes-
ityl)P was obtained by metalating H2(AP)3(mesityl)P with zinc
acetate dihydrate in CH2Cl2/MeOH; yield 0.20 g, 78%. 1H NMR
(300 MHz, [D6]DMSO): δ = 8.82–8.80 (a singlet overlapping with
a doublet, 6 H, pyrrolic H), 8.50 [d, J(H,H) = 4.5 Hz, 2 H, pyrrolic
H], 7.79 [d, J(H,H) = 7.8 Hz, 6 H, Ar–H], 7.29 (s, 2 H, Ar–H),
6.94 [d, J(H,H) = 8.0 Hz, 6 H, Ar–H], 5.46 (s, 6 H, NH2), 2.57 (s,
3 H, CH3), 1.76 (s, 6 H, CH3) ppm. 13C NMR (75 MHz, [D6]-
DMSO): δ = 149.87, 149.73, 148.69, 147.99, 139.49, 138.47, 136.71,
135.18, 132.13, 131.37, 130.34, 130.21, 129.47, 127.57, 121.37,
120.72, 116.94, 112.98, 112.27, 109.59, 21.54, 21.10 ppm. MS
(FAB+): m/z calcd. for C47H37N7Zn: 763.24; found 763.3.
MS (FAB+): m/z calcd. for C83H55N13O12Zn: 1489.34; found
1490.2. Due to the solubility problem, we could not obtain a 13C
spectrum.
5,10,15,20-Tetrakis[4-{bis(4-chlorophenyl)amino}phenyl]-
porphyrinatozinc (4): Zn(AP)4P (0.10 g, 0.135 mmol), 1-chloro-4-
iodobenzene (2.58 g, 10.837 mmol), Cu (0.69 g, 10.837 mmol),
K2CO3 (1.31 g, 9.450 mmol), [18]crown-6 (0.11 g, 0.410 mmol);
1
yield 0.12 g, 53%. H NMR (300 MHz, CDCl3): δ = 9.08 (s, 8 H,
pyrrolic H), 8.11 [d, J(H,H) = 8.4 Hz, 8 H, Ar–H], 7.45–7.31 (m,
40 H, Ar–H) ppm. 13C NMR (75 MHz, [D7]DMF): δ = 150.67,
147.23, 147.10, 139.09, 136.56, 132.25, 130.47, 128.30, 126.52,
122.84, 120.87 ppm. MS(MALDI-TOF): m/z calcd. for
C92H56N8O8Zn: 1621.14; found 1621.59.
5-[4-(Diphenylamino)phenyl]-10,15,20-trimesityporphyrinatozinc (5):
Zn(AP)-(mesityl)3P (20.0 mg, 0.024 mmol), iodobenzene (15.3 mg,
0.075 mmol), Cu (4.8 mg, 0.075 mmol), K2 CO3 (6.9 mg,
0.050 mmol), [18]crown-6 (6.6 mg, 0.025 mmol); yield 0.02 g, 70%.
1H NMR (300 MHz, CD2Cl2): δ = 9.02 [d, J(H,H) = 4.7 Hz, 2 H,
pyrrolic H], 8.76 [d, J(H,H) = 4.6 Hz, 2 H, pyrrolic H], 8.68 (s, 4
H, pyrrolic H), 8.08 [d, J(H,H) = 8.3 Hz, 2 H, Ar–H], 7.44–7.39
(m, 10 H, Ar–H), 7.30 (s, 6 H, Ar–H), 7.12 [t, J(H,H) = 4.3 Hz, 2
H, Ar–H], 2.62 (s, 9 H, CH3), 1.83 (s, 18 H, CH3) ppm. 13C NMR
(75 MHz, CDCl3): δ = 150.06, 149.80, 149.75, 149.68, 147.98,
147.08, 143.34, 139.30, 137.25, 137.14, 135.70, 135.30, 132.04,
131.19, 130.94, 130.41, 129.71, 129.41, 128.73, 127.57, 127.16,
124.67, 123.04, 121.78, 121.48, 119.84, 118.88, 118.57, 118.22,
21.67, 21.45 ppm. MS (FAB+): m/z calcd. for C65H55N5Zn: 969.37;
found 970.4.
5-[4-{Bis(4-nitrophenyl)amino}phenyl]-10,15,20-trimesitylpor-
phyrinatozinc (1): Zn(AP)(mesityl)3P (50.0 mg, 0.061 mmol), 4-
fluoronitrobenzene (34.6 mg, 0.245 mmol), CsF (185.5 mg,
1.221 mmol). The crude product was dissolved and passed through
a silica gel column. The final product can be obtained by using
1
hexane and CH2Cl2 mixed solvent as eluent; yield 0.04 g, 64%. H
NMR (300 MHz, CD2Cl2): δ = 8.99 [d, J(H,H) = 4.6 Hz, 2 H,
pyrrolic H], 8.81 [d, J(H,H) = 4.6 Hz, 2 H, pyrrolic H], 8.72 (s, 4
H, pyrrolic H), 8.33–8.29 [dd, J(H,H) = 8.4 and 9.2 Hz, 6 H, Ar–
H], 7.59 [d, J(H,H) = 8.3 Hz, 2 H, Ar–H], 7.51 [d, J(H,H) = 9.2 Hz,
4 H, Ar–H], 7.31 and 7.30 (two overlapping singlets, 6 H, Ar–H),
2.63 and 2.62 (two overlapping singlets, 9 H, CH3), 1.85 (s, 18 H,
CH3) ppm. 13C NMR (75 MHz, CD2Cl2): δ = 152.54, 150.41,
150.18, 150.06, 144.69, 143.44, 142.03, 139.54, 139.31, 139.23,
138.00, 136.65, 132.11, 131.57, 131.47, 131.03, 128.02, 125.99,
125.42, 123.30, 119.40, 119.00, 21.78, 21.74, 21.55 ppm. MS
(FAB+): m/z calcd. for C65H53N7O4Zn: 1059.35; found 1060.6.
5,15-Bis[4-(diphenylamino)phenyl]-10,20-dimesitylporphyrinatozinc
(6): Zn-(AP)2(mesityl)2P (150.0 mg, 0.189 mmol), 4-iodobenzene
(385.0 mg, 1.887 mmol), Cu (150.0 mg, 2.360 mmol), K2CO3
(260.0 mg, 1.881 mmol), [18]crown-6 (16.0 mg, 0.061 mmol); yield
1
0.09 g, 42%. H NMR (300 MHz, CD2Cl2): δ = 9.04 [d, J(H,H) =
3.9 Hz, 4 H, pyrrolic H], 8.78 [d, J(H,H) = 3.7 Hz, 4 H, pyrrolic
H], 8.08 [d, J(H,H) = 7.9 Hz, 4 H, Ar–H], 7.44–7.40 (m, 20 H, Ar–
H), 7.31 (s, 4 H, Ar–H), 7.13 (t, 4 H, Ar–H), 2.64 (s, 6 H, CH3),
1.83 (s, 12 H, CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 150.29,
149.85, 147.94, 147.22, 139.29, 139.10, 137.42, 136.70, 135.30,
132.33, 130.67, 129.45, 127.63, 124.77, 123.14, 121.39, 120.09,
119.19, 21.61, 21.48 ppm. MS (FAB+): m/z calcd. for C74H58N6Zn:
1094.4; found 1096.3.
5,15-Bis[4-{bis(4-nitrophenyl)amino}phenyl]-10,20-dimesitylpor-
phyrinatozinc (2): Zn(AP)2(mesityl)2P (70.0 mg, 0.088 mmol), 4-
fluoronitrobenzene (500.0 mg, 3.544 mmol), CsF (810.0 mg,
5.332 mmol). The crude was washed by acetone and CH2Cl2 until
yellow filtrate became reddish brown. The solid maintain on filter
5,10,15-Tris[4-(diphenylamino)phenyl]-20-mesitylporphyrinatozinc
(7): Zn-(AP)3(mesityl)P (140.0 mg, 0.183 mmol), iodobenzene
(12.0 g, 0.059 mol), Cu (0.8 g, 0.013 mol), K2CO3 (1.54 g,
0.011 mol), [18]crown-6 (44.4 mg, 0.168 mmol); yield 0.09 g, 41%.
1H NMR (300 MHz, [D6]DMSO): δ = 8.91–8.87 (a singlet overlap-
ping with a doublet, 6 H, pyrrolic H), 8.59 [d, J(H,H) = 4.6 Hz, 2
H, pyrrolic H], 8.06 [d, J(H,H) = 8.2 Hz, 6 H, Ar–H], 7.47–7.31
(m, 32 H, Ar–H), 7.15 [t, J(H,H) = 7.1 Hz, 6 H, Ar–H], 2.58 (s, 3
H, CH3), 1.77 (s, 6 H, CH3) ppm. 13C NMR (75 MHz, CDCl3): δ
= 150.26, 149.89, 147.87, 147.18, 139.27, 139.04, 137.41, 136.85,
136.70, 135.43, 135.37, 132.43, 131.85, 130.76, 129.45, 127.64,
124.73, 123.11, 121.44, 121.36, 120.93, 120.47, 119.11, 21.73,
21.50 ppm. MS (FAB+): m/z calcd. for C83H61N7Zn: 1219.43;
found 1221.3.
1
paper is the final product; yield 0.02 g, 18%. H NMR (300 MHz,
[D7]DMF): δ = 8.99 [d, J(H,H) = 4.7 Hz, 4 H, pyrrolic H], 8.71 [d,
J(H,H) = 4.4 Hz, 4 H, pyrrolic H], 8.43–8.36 [dd, J(H,H) = 9.1
and 8.1 Hz, 12 H, Ar–H], 7.79 [d, J(H,H) = 7.8 Hz, 4 H, Ar–H],
7.72 [d, J(H,H) = 9.3 Hz, 8 H, Ar–H], 7.40 (s, 4 H, Ar–H), 2.65 (s,
6 H, CH3), 1.88 (s, 12 H, CH3) ppm. MS (FAB+): m/z calcd. for
C74H54N10O8Zn: 1274.34; found 1276.3. Due to the solubility
problem, we could not obtain a 13C spectrum.
5,10,15-Tris[4-{bis(4-nitrophenyl)amino}phenyl]-20-mesitylpor-
phyrinatozinc (3): Zn(AP)3(mesityl)P (75.0 mg, 0.098 mmol), 4-
fluoronitrobenzene (186.0 mg, 1.318 mmol), CsF (980.0 mg,
6.451 mmol). The crude product was dissolved and passed through
a silica gel column. The final product can be obtained by using
CH2Cl2 as eluent; yield 0.04 g, 24%. 1H NMR (300 MHz, CD2Cl2):
δ = 9.12 (s, 4 H, pyrrolic H), 9.04 [d, J(H,H) = 4.7 Hz, 2 H, pyrrolic
5-[4-(Ditolylamino)phenyl]-10,15,20-trimesitylporphyrinatozinc (9):
Zn-(AP)(mesityl)3P (50.0 mg, 0.061 mmol), 4-iodotoluene
(106.4 mg, 0.488 mmol), Cu (31 mg, 0.488 mmol), K2CO3 (56.2 mg,
0.407 mmol), [18]crown-6 (16.1 mg, 0.061 mmol); yield 0.05 g,
1
H], 8.87 [d, J(H,H) = 4.7 Hz, 2 H, pyrrolic H], 8.34–8.29 (m, 18 78%. H NMR (300 MHz, CD2Cl2): δ = 9.03 [d, J(H,H) = 4.6 Hz,
H, Ar–H), 7.64–7.59 (m, 6 H, Ar–H), 7.54–7.49 (m, 12 H, Ar–H), 2 H, pyrrolic H], 8.75 [d, J(H,H) = 4.6 Hz, 2 H, pyrrolic H], 8.68
7.34 (s, 2 H, Ar–H), 2.66 (s, 3 H, CH3), 1.84 (s, 6 H, CH3) ppm.
(s, 4 H, pyrrolic H), 8.04 [d, J(H,H) = 8.5 Hz, 2 H, Ar–H], 7.37–
Eur. J. Inorg. Chem. 2012, 1038–1047
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1045

Y. O. Su et al.
FULL PAPER
7.20 (m, 16 H, Ar–H), 2.63 and 2.61 (two singlet overlapped, 9 H,
149.74, 148.08, 141.14, 139.31, 139.20, 137.35, 135.15, 134.63,
CH3), 2.38 (s, 6 H, CH3), 1.84 and 1.83 (two singlet overlapped, 18 132.38, 130.50, 127.60, 126.94, 120.37, 119.01, 118.22, 114.87,
H, CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 150.19, 149.85, 5 5 . 5 4 , 2 1 . 6 1 , 2 1 . 4 8 p p m . M S ( FA B+ ) : m/ z c a l c d . fo r
149.75, 149.69, 147.53, 145.48, 139.30, 139.13, 139.01, 137.33, C78H66N6O4Zn: 1214.44; found 1214.4.
135.80, 135.14, 132.77, 132.24, 131.02, 130.45, 130.06, 127.60,
5,10,15-Tris[4-{bis(4-methoxyphenyl)amino}phenyl]-20-mesityl-
125.01, 120.28, 120.16, 118.70, 118.30, 21.73, 21.66, 21.47,
20.90 ppm. MS (FAB+): m/z calcd. for C67H59N5Zn: 997.41; found
998.6.
porphyrinatozinc (15): Zn(AP)3(mesityl)P (0.12 g, 0.157 mmol), 4-
iodoanisole (2.97 g, 0.013 mol), Cu (0.69 g, 0.011 mol), K2CO3
(1.32 g, 9.551 mmol), [18]crown-6 (0.04 g, 0.144 mmol); yield
0.07 g, 33%. 1H NMR (300 MHz, CDCl3): δ = 9.09 (s, 4 H, pyrrolic
H), 9.04 [d, J(H,H) = 4.6 Hz, 2 H, pyrrolic H], 8.78 [d, J(H,H) =
4.7 Hz, 2 H, pyrrolic H], 8.01 [d, J(H,H) = 8.4 Hz, 6 H, Ar–H],
7.37–7.28 (m, 20 H, Ar–H), 6.95 [d, J(H,H) = 8.9 Hz, 12 H, Ar–
H], 3.83 (s, 18 H, OCH3), 2.65 (s, 3 H, CH3), 1.84 (s, 6 H, CH3)
ppm. 13C NMR (75 MHz, CDCl3): δ = 155.95, 150.39, 150.35,
150.29, 149.78, 148.05, 141.10, 139.31, 139.16, 137.33, 135.27,
135.22, 134.85, 134.68, 132.41, 131.78, 130.53, 127.59, 126.93,
121.23, 120.69, 118.78, 118.22, 118.17, 114.84, 55.52, 21.69,
21.48 ppm. MS (FAB+): m/z calcd. for C89H73N7O6Zn: 1399.49;
found 1400.7.
5,15-Bis[4-(ditolylamino)phenyl]-10,20-dimesitylporphyrinatozinc
(10): Zn(AP)2(mesityl)2P (150.0 mg, 0.189 mmol), 4-iodotoluene
(410.0 mg, 1.880 mmol), Cu (150.0 mg, 2.360 mmol), K2CO3
(260.0 mg, 1.881 mmol), [18]crown-6 (16.0 mg, 0.061 mmol); yield
1
0.09 g, 41%. H NMR (300 MHz, CDCl3): δ = 9.03 [d, J(H,H) =
4.7 Hz, 4 H, pyrrolic H], 8.78 [d, J(H,H) = 4.6 Hz, 4 H, pyrrolic
H], 8.04 [d, J(H,H) = 8.5 Hz, 4 H, Ar–H], 7.38 [d, J(H,H) = 8.5 Hz,
4 H, Ar–H], 7.31–7.29 (a doublet overlap-ping with a singlet, 12
H, Ar–H), 7.20 [d, J(H,H) = 8.3 Hz, 8 H, Ar–H], 2.65 (s, 6 H,
CH3), 2.39 (s, 12 H, CH3), 1.84 (s, 12 H, CH3) ppm. 13C NMR
(75 MHz, CDCl3): δ = 150.36, 149.79, 147.58, 145.48, 139.30,
139.15, 137.37, 135.68, 135.18, 132.80, 132.36, 130.57, 130.07,
127.61, 125.05, 120.26, 120.12, 119.09, 21.61, 21.48, 20.90 ppm. MS
(FAB+): m/z calcd. for C78H66N6Zn: 1150.46; found 1151.4.
Supporting Information (see footnote on the first page of this arti-
1
cle): H NMR spectra, absorption spectra, excitation profiles, and
cyclic voltammograms of Por–TPA conjugates are shown in the
Supporting Information. The emission spectra obtained from the
study of antenna effect and the absorption spectra of the radical
cation of Por–TPA conjugates are also shown.
5,10,15-Tris[4-(ditolylamino)phenyl]-20-mesitylporphyrinatozinc
(11): Zn-(AP)3(mesityl)P (0.12 g, 0.157 mmol), 4-iodotoluene
(2.70 g, 0.013 mol), Cu (0.69 g, 0.011 mol), K2CO3 (1.32 g,
9.551 mmol), [18]crown-6 (0.04 g, 0.144 mmol); yield 0.10 g, 48%.
1H NMR (300 MHz, CD2Cl2): δ = 9.12 (s, 4 H, pyrrolic H), 9.06
[d, J(H,H) = 4.7 Hz, 2 H, pyrrolic H], 8.78 [d, J(H,H) = 4.7 Hz, 2
H, pyrrolic H], 8.07–8.03 [dd, J(H,H) = 8.4 and 8.5 Hz, 6 H, Ar–
H], 7.40–7.21 (m, 32 H, Ar–H), 2.64 (s, 3 H, CH3), 2.38 (s, 18 H,
CH3), 1.84 (s, 6 H, CH3) ppm. 13C NMR (75 MHz, CD2Cl2): δ =
150.70, 150.16, 148.03, 145.77, 139.52, 137.89, 136.07, 135.95,
135.65, 135.58, 133.38, 132.73, 132.10, 130.83, 130.40, 127.96,
125.44, 121.46, 121.03, 120.30, 119.31, 21.76, 21.54, 20.96 ppm. MS
(FAB+): m/z calcd. for C89H73N7Zn: 1303.52; found 1304.4.
Acknowledgments
This work was supported by the National Science Council of the
Republic of China (97-2113-M-260-005-MY3). We also thank Prof.
Cheng for providing conjugates 8 and 12.
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porphyrinatozinc (13): Zn(AP)(mesityl)3P (50.0 mg, 0.061 mmol), 4-
iodoanisole (114.2 mg, 0.488 mmol), Cu (31.0 mg, 0.488 mmol),
K2CO3 (56.2 mg, 0.407 mmol), [18]crown-6 (16.1 mg, 0.061 mmol);
yield 0.05 g, 74 %. 1H NMR (300 MHz, CDCl3): δ = 9.01 [d,
J(H,H) = 4.6 Hz, 2 H, pyrrolic H], 8.77 [d, J(H,H) = 4.6 Hz, 2 H,
pyrrolic H], 8.69 (s, 4 H, pyrrolic H), 8.00 [d, J(H,H) = 8.4 Hz, 2
H, Ar–H], 7.35 [d, J(H,H) = 8.9 Hz, 4 H, Ar–H], 7.30–7.26 (a
doublet and a singlet overlapping with solvent peak, 8 H, Ar–H),
6.95 [d, J(H,H) = 8.9 Hz, 4 H, Ar–H], 3.84 (s, 6 H, OCH3), 2.64
and 2.62 (two singlets overlapped, 9 H, CH3), 1.85 (s, 18 H, CH3)
ppm. 13C NMR (75 MHz, CDCl3): δ = 156.02, 150.30, 149.87,
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134.81, 132.28, 130.99, 130.40, 127.61, 126.90, 120.47, 118.68,
118.32, 114.89, 114.20, 55.55, 21.72, 21.65, 21.46 ppm. MS (FAB+):
m/z calcd. for C67H59N5O2Zn: 1029.4; found 1029.6.
5,15-Bis[4-{bis(4-methoxyphenyl)amino}phenyl]-10,20-dimesityl-
porphyrinatozinc (14): Zn(AP)2(mesityl)2P (100.0 mg, 0.126 mmol),
4-iodoanisole (275.0 mg, 1.175 mmol), Cu (96.0 mg, 1.511 mmol),
K2 CO3 (139.5 mg, 1.009 mmol), [18]crown-6 (16.0 mg,
1
0.061 mmol); yield 0.05 g, 31%. H NMR (300 MHz, CDCl3): δ =
9.02 [d, J(H,H) = 4.6 Hz, 4 H, pyrrolic H], 8.77 [d, J(H,H) =
4.7 Hz, 4 H, pyrrolic H], 8.01 [d, J(H,H) = 8.5 Hz, 4 H, Ar–H],
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ping with a singlet, 8 H, Ar–H), 6.95 [d, J(H,H) = 8.9 Hz, 8 H,
Ar–H], 3.84 (s, 12 H, OCH3), 2.65 (s, 6 H, CH3), 1.83 (s, 12 H,
CH3) ppm. 13C NMR (75 MHz, CDCl3): δ = 156.02, 150.44,
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Received: September 30, 2011
Published Online: January 30, 2012
Eur. J. Inorg. Chem. 2012, 1038–1047
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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