Porphyrins Containing a Triphenylamine Donor and up to Eight Alkoxy

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Porphyrins containing a triphenylamine donor and up to eight alkoxy chains for dye-sensitized solar cells: a high efficiency of 10.9% Yunyu Tang, Yueqiang Wang, Xin Li, Hans Ågren, Wei-Hong Zhu, and Yongshu Xie ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.5b10624 • Publication Date (Web): 26 Nov 2015 Downloaded from http://pubs.acs.org on November 27, 2015

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Porphyrins containing a triphenylamine donor and up to eight alkoxy chains for dye-sensitized solar cells: a high efficiency of 10.9% Yunyu Tang†, Yueqiang Wang†, Xin Li*‡, Hans Ågren‡, Wei-Hong Zhu†, and Yongshu Xie*† † Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai 200237, P. R. China ‡ Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, SE10691 Stockholm, Sweden KEYWORDS: dye, porphyrin, sensitizers, cosensitization, solar cells ABSTRACT: Porphyrins are promising DSSC sensitizers due to their structural similarity to chlorophylls as well as their tunable strong absorption. Herein, a novel D−π−A porphyrin dye XW14 containing a strongly electron-donating triphenylamine moiety as the electron donor was designed and synthesized. To avoid undesirably decreased Voc caused by dye aggregation effect, two methoxy or hexyloxy chains were introduced to the para-positions of the triphenylamine moiety to afford XW15 and XW16, respectively. To further extend the absorption to a longer wavelength, a benzothiadiazole unit was introduced as an auxiliary acceptor to furnish XW17. Compared with XW14, the introduction of additional methoxy or hexyloxy groups in XW15 and XW16 red-shift the onset wavelengths from 760 nm to 780 and 790 nm, respectively. More impressively, XW17 has a more extended π-conjugation framework, and thus it exhibits a much broader IPCE spectrum with an extremely red-shifted onset wavelength of 830 nm, resulting in the highest Jsc (18.79 mA cm-2). On the other hand, the hexyloxy chains are favorable for suppressing the dye aggregation effect, and thus XW16 shows the highest Voc of 734 mV. As a result, XW16 and XW17 demonstrate photovoltaic efficiencies of 9.1% and 9.5%, respectively, higher than those of XW14 (8.6%) and XW15 (8.7%), and obviously higher than that of 7.94% for our previously reported dye XW4. Based on optimized porphyrin dye XW17, a non-porphyrin dye with a high Voc and strong absorption around 500 nm (WS-5) was used as the cosensitizer to improve the Voc from 700 to 748 mV, with synergistical Jsc enhancement from 18.79 to 20.30 mA cm-2. Thus, the efficiency was dramatically enhanced to 10.9%, which is among the highest efficiencies obtained for the DSSCs based on traditional iodine electrolyte. In addition, the DSSCs based on XW17+WS-5 exhibit good photostability, which is beneficial for practical applications.

INTRODUCTION Dye-sensitized solar cells (DSSCs) have been extensively investigated for utilizing solar energy because of their low cost, ease of fabrication, relatively high photovoltaic efficiency and aesthetic features of vivid colour and transparency.1-2 In a typical DSSC, the sensitizer exerts an essential influence on light-harvesting. Based on the initial researches on ruthenium complex sensitizers,3 organic sensitizers with the donor–π–acceptor (D–π–A) configuration have been demonstrated to be promising due to the structural design flexibility, low material costs, and high molecular absorption coefficients.4-9 Porphyrins are particularly promising DSSC sensitizers due to their structural similarity to chlorophylls, and their tunable strong absorption.10-11 Thus, numerous porphyrin dyes have been reported for developing efficient DSSCs.1014 In spite of the successful examples, typical porphyrins

exhibit poor light-harvesting capability beyond 700 nm.1516 In this respect, the introduction of additional ethynylene bridges can expand the π framework and thus improve the absorption in the NIR region.15,17-20 However, this approach usually induces unfavorable severe dye aggregation, which may lower the photovoltage and the photovoltaic efficiency. To address this problem, flexible substituents have been introduced to suppress the aggregation.21-22 In this respect, we have developed porphyrin dyes for systematic improving the DSSC efficiencies.23-30 Among them, XW4 (Chart 1) contains a carbazole moiety as the electron donor, and up to six alkoxy chains to suppress the adverse aggregation effect caused by the presence of two ethynylene units, and thus it exhibits a photovoltaic efficiency of 7.94%.23 Considering the relatively weak electron donating ability of the carbazole moiety, it is anticipated that the efficiency may be further improved

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by using a stronger electron donor.31-32 Thus, XW11 was synthesized by introducing a phenothiazine moiety as the electron donor, and a benzothiadiazole group (BTD) as the extra acceptor to extend the absorption to a longer wavelength.30 Thus, an efficiency of 9.3% was achieved for the DSSCs based on XW11, higher than that for XW4. C12H25O

OC12H25

R

N N

N

R

OC6H13 I

COOH

Zn

N

triphenylamine, and the acid ester of the acceptor through Sonogashira coupling reactions to introduce the donor and the acid ester of the acceptor to the mesopositions of the porphyrin framework. Finally, the target dyes were obtained through hydrolysis of the esters. The chemical structures were characterized with 1H NMR, 13C NMR and HRMS (See the Supporting Information). Scheme 1. Synthetic Routes for XW14 − XW17.

C6H13O N

C12H25O

C12H25O

COOH

A1:

OC6H13

N

N

A2:

OC6H13 R

N

A

Zn

C12H25O

S

COOH

N

iv

C12H25O

Zn

D N

OC12H25

C12H25O

OC12H25 N

N

Br

v

OC12H25

Zn

D N

OC12H25

6a~6d

5a~5c

vi A1 =

S

N

COOMe

COOMe

6a~6c

C12H25O

6d

COOH N

Chart 1. Molecular structures of the porphyrin dyes and the cosensitizer WS-5.

S

N Zn

D N

COOH

XW14~XW16

OC12H25 N

N

COOH

A2 =

C12H25O

XW17

On the other hand, porphyrins are known to demonstrate rather weak absorption around 500 nm.19,37 The utilization of a cosensitizer may dramatically compensate the absorption in this region, and thus further enhance the photovoltaic efficiency. Hence, we further utilize WS538 as a cosensitizer. As a consequence, a high PCE of 10.9% was obtained for XW17+WS-5, which is among the highest efficiencies obtained for the DSSCs based on traditional iodine electrolyte.

A2 N OC12H25

XW14~XW17 OC6H13

OMe

In fact, the triphenylamine group has also been used as a strong electron donor to design efficient DSSC dyes.33-35 Thus, more efficient porphyrin dyes may be developed by employing a triphenylamine-based donor and introducing additional long alkoxyl chains. Thus, four novel porphyrin dyes XW14 – XW17 (Chart 1) containing the triphenylamine electron donor have been designed and synthesized in this work. The dye structures were optimized in a stepwise manner: i) introducing two additional alkoxy chains to triphenylamine to further suppress the dye aggregation; ii) a benzothiadiazole (BTD) unit was introduced as an auxiliary acceptor to further extend the absorption to a longer wavelength.36 Based on the molecular structure optimization, a power conversion efficiency (PCE) of 9.5% was thus achieved for XW17, which is slightly higher than that of 9.3% achieved for XW11.

A1 N

C12H25O

OC12H25

N

CN

WS-5

N

N

N

C12H25O

ZnP-Br2

XW14: R = H, A= A1; XW15: R = OMe, A = A1; XW16: R = OC6H13, A = A1; XW17: R = OC6H13, A = A2. S

Br

3a: R = H 3b: R = OMe 3c: R = OC6H13

C12H25O

N

N

OC12H25

C8H17 N N N

Zn

Br

N

N

4a: R = H 4b: R = OMe 4c: R = OC6H13

TMS

2a: R = H 2b: R = OMe 2c: R = OC6H13

OC12H25 N

N

N N

C6H13O

I

R

OC12H25

R N OC6H13

C6H13O

C6H13O

1a: R = H 1b: R = OMe 1c: R = OC6H13

XW4

R

iii

OC6H13

OC6H13 OC6H13

OC12H25

R N

ii

N

I

C12H25O

R

R

i

NH

OC6H13

R

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OC6H13

OC6H13

N

D= C6H13O

OC6H13

D=

N

D=

OMe

5a, 6a, XW14

N C6H13O

C6H13O

5b, 6b, XW15

OC6H13

5c, 6c, 6d, XW16, XW17

Reaction conditions: (i) 1a, 1b or 1c, 1,4-bis(hexyloxy)-2,5diiodobenzene, CuI, trans-1,2-cyclohexanediamine, K3PO4, 1,4-dioxane; (ii) Pd(PPh3)2Cl2, CuI, trimethylsilylacetylene, THF, Et3N; (iii) KOH, MeOH, H2O; (iv) 4a, 4b or 4c, AsPh3, Pd2(dba)3, THF, Et3N; (v) methyl 4ethynylbenzoate or methyl 4-(7-ethynylbenzo[c] [1,2,5] thiadiazol-4-yl)benzoate, Pd(PPh3)4, CuI, TEA, THF; (vi) LiOH⋅H2O, THF, H2O. Optical Properties The UV-Vis absorption spectra of XW14 – XW17 in THF solutions are shown in Figure 1 and the corresponding spectroscopic data are summarized in Table 1.

RESULTS AND DISCUSSION Syntheses and characterization As depicted in Scheme 1, the dibromoporphyrin28 was used to successively react with the acetylene derivatives of

Figure 1. Absorption spectra of XW14 – XW17 in THF.


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Table 1. Absorption and emission data for the dyes in THF. Dye

Absorption λmax [nm] 3

-1

-1

a

(ε [10 M cm ])

Emission λmax [nm]a

XW14

461 (214), 589 (6.5), 619 (9.0), 668 (60.0)

680

XW15

461 (157), 592 (7.0), 626 (10.5), 673 (63.9)

689

XW16

458 (127), 591 (6.4), 626 (9.5), 674 (47.8)

690

XW17

469 (119), 650 (17.6), 693 (73.3)

728

is beneficial for improving light-harvesting and enhancing Jsc. Electrochemical Properties Cyclic voltammetry (CV) (Figure 3, Table 2) was carried out to investigate the possibility of electron transfer from the sensitizer molecules to TiO2 and the regeneration of the sensitizers, which are necessary processes for realizing the photovoltaic behavior of DSSCs.

a

The absorption and emission data were measured in THF. Excitation wavelengths/nm: 461 (XW14), 461 (XW15), 458 (XW16), 469 (XW17).

Figure 3. The cyclic voltammetry curves of the dyes adsorbed to a nanocrystalline TiO2 film deposited on conducting FTO glass. Table 2. Electrochemical properties of the porphyrin dyes.

XW14

Eoxa /V (vs. NHE) 0.72

1.84

Eox*c /V (vs. NHE) -1.12

XW15

0.66

1.82

-1.16

XW16

0.66

1.82

-1.16

XW17

0.68

1.75

-1.07

Dye Figure 2. Absorption spectra of XW14 – XW17 anchored on transparent TiO2 films (3 μm). As expected, the absorption spectra of the porphyrin dyes exhibit a typical intense Soret band within 400–500 nm and less intense Q bands in a range of 550–750 nm (Figure 1, Table 1). Both bands of XW14 are broadened and red-shifted for ca. 6 nm relative to those of XW4, which can be rationalized by the stronger electron-donating ability of the triphenylamine moiety respect to the carbazole. Compared with XW14, the introduction of methoxy or hexyloxy groups to the triphenylamine in XW15 and XW16 were observed to induce red shift of the Q bands for 5 nm and 6 nm, respectively. The molecular structure of XW15 is quite similar to the reported porphyrin dye YD20.39 The main difference is that XW15 contains two additional hexyloxy groups on the phenylene group intermediate between the donor and the ethynylene moiety, which results in a 6 nm red shift of the Q band, indicating that the hexyloxy groups are not only favorable for suppressing dye aggregation but also can extend the absorption to longer wavelengths. Furthermore, the insertion of the electron-withdrawing BTD group into XW17 dramatically red-shifted the λmax of the Q band to 693 nm, achieving a striking onset absorption wavelength of 760 nm. In addition, the Soret band of XW17 is broader than those for XW14-XW16, suggesting that the auxiliary benzothiadiazole acceptor is effective for extending the absorption bands, similar to that observed for XW11 and SM315.30,36 Upon adsorption to 3 µm thick TiO2 films, the absorption spectra of XW14 – XW17 are broadened (Figure 2), which

E0-0b/V

a

The ground state oxidation potential (Eox) of dyes were estimated in acetonitrile using 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the electrolyte (working electrode: FTO/TiO2/dye; reference electrode: SCE; calibrated with ferrocene/ferrocenium (Fc/Fc+) as an external reference. Counter electrode: Pt). b E0-0 was estimated from the wavelength at the intersection (λinter) of normalized absorption and emission spectra with the equation E0-0 = 1240/λinter. c The Eox* was estimated from the equation of Eox* = Eox− E0–0. The estimated ground state oxidation potentials (Eox) of XW14 − XW17 are 0.72, 0.66, 0.66 and 0.68 V (Figure 3, Table 2), respectively, versus the normal hydrogen electrode (NHE). Their Eox are more positive than the iodide/triiodide redox couple (~0.4 V), indicating that the oxidized dyes can be efficiently regenerated by the electrolyte. The energy gap E0-0 (1.84 V, 1.82 V, 1.82 V and 1.75 V for XW14, XW15, XW16 and XW17, respectively) were calculated from the intersection points (λinter) of normalized UV-Vis absorption and emission spectra of the sensitizers with the equation E0-0 = 1240/λinter. The excited-state oxidation potentials (Eox*), calculated from Eox - E0–0, lie in the range from -1.16 to -1.07 V (Table 2), considerably more negative than the conduction band edge (CB) of



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TiO2 (-0.5 V), energetically allowing an efficient electron injection into the TiO2 conduction band from the excited sensitizers.40 The ground state and the excited-state oxidation potentials correspond to the HOMO and LUMO energies, respectively. From these values, we can attain a schematic energy-level diagram for the HOMO and LUMOs of XW14 − XW17 (Figure 4).9,41 It is obvious that the introduction of a benzothiadiazole group into XW17 results in the lowest electrochemical energy gap among all the dyes, which agree with its red shifted absorption spectrum.

Figure 4. Schematic energy-level diagram of XW14 – XW17. Molecular calculations To provide further insight into the effect of varying the molecular structures on electron distribution in the frontier molecular orbitals and the absorption spectra, density functional theory (DFT) calculations and time-dependent density functional theory (TDDFT) calculations were employed using the Gaussian 09 program package.42-45 According to the corresponding molecular orbital profiles (Figure 5), the electrons of the HOMO levels for all the dyes mainly distribute over the donor and the porphyrin framework, while the LUMO orbitals are predominantly delocalized over the anchoring group and the porphyrin macrocycle. These distribution characters facilitate the electron injection from the dyes to the TiO2 surface. The simulated absorption spectra are shown in Figure S1, and the corresponding data are collected in Table S1. The in-

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tense Soret band around 450 nm corresponds to the local excitation of the zinc-porphyrin. The absorption band of the S0 → S1 excitation for XW17 is obviously shifted to around 700 nm, owing to its more delocalized LUMO (Figure 5). In addition to the normal Soret and Q bands, a shoulder peak appears at about 440 nm, which can be ascribed to the charge-transfer excitation from the donor to the ancillary acceptor BTD (HOMO-1 → LUMO+1, Table S1). Photovoltaic Performance of DSSCs

Figure 6. IPCE action spectra for XW14 – XW17-based DSSCs. The photovoltaic properties of the devices sensitized by XW14 – XW17 were evaluated with an iodine electrolyte. The incident photon-to-current conversion efficiency (IPCE) spectra for all the four dyes exhibit a broad spectral response within a large wavelength range (Figure 6), indicating that all the dyes can efficiently convert the visible light into photocurrent. Compared with XW14, the introduction of additional methoxy or hexyloxy groups in XW15 and XW16 red-shift the onset wavelengths from 760 nm to 780 and 790 nm, respectively. More impressively, XW17 contains an additional BTD group and has a more extended π-conjugation framework, and thus it shows a much broader IPCE spectrum with the onset wavelength at an impressively long wavelength of 830 nm. Thus, their onset wavelength thresholds (Figure 6) lie in the order of XW14 < XW15 ≈ XW16 < XW17, which is in consistent with the sequence of photocurrent Jsc (vide infra).

Figure 5. Frontier molecular orbital profiles of XW14 – XW17 calculated by DFT.


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Table 3. Photovoltaic parameters of the porphyrin dye sensitized solar cells under AM1.5 illumination (power 100 mW⋅cm-2). Jsc/mA cm-

Dye

2

XW14

17.07±0.09

XW15

18.02±0.15

XW16

17.92±0.13

XW17

18.79±0.22

XW14+ WS-5 XW15+ WS-5 XW16+ WS-5 XW17+ WS-5

18.54±0.11 18.88±0.08 19.01±0.14 20.30±0.20

Voc/ mV 725 ±3 720 ±5 734 ±2 700 ±4 765 ±3 763 ±5 773 ±2 748 ±3

FF

PCE (%)

0.70±0.01

8.6±0.1

0.67±0.01

8.7±0.1

0.70±0.01

9.1±0.1

0.72±0.01

9.5±0.1

0.70±0.01

9.9±0.1

0.71±0.01

10.1±0.2

0.72±0.01

10.4±0.2

0.72±0.01

10.9±0.1

The photocurrent–voltage (J–V) characteristics of the DSSCs based on XW14 – XW17 are shown in Figure 7 and the photovoltaic parameters are presented in Table 3. The efficiencies lie in the range of 8.6%–9.5%, obviously higher than that of 7.94% for XW4, which is mainly related to the enhanced photocurrent (Jsc). To be more specific, the Jsc values within 17.07–18.02 mA cm-2 for XW14 – XW16 are higher than that of 16.22 mA cm-2 for XW4, which may be ascribed to the broadened absorption caused by the enhanced electron-donating ability of the triphenylamine group relative to the carbazole group in XW4. The highest Jsc of 18.79 mA cm-2 achieved for XW17 is consistent with its broadest absorption due to the presence of the additional BTD group. On the other hand, the introduction of the hexyloxy chains is favorable for suppressing the dye aggregation effect and preventing the penetration of I3from the electrolyte into the TiO2 film, thus XW16 shows the highest open voltage (Voc) of 734 mV. As a result, XW16 and XW17 demonstrate DSSC efficiencies of 9.1% and 9.5%, respectively, higher than those of XW14 and XW15.

Figure 7. J–V characteristics of the DSSCs based on XW14 – XW17.

All the porphyrin dyes XW14 – XW17 exhibit very weak absorption within 500–600 nm (Figure 1), and the IPCE spectra also exhibit a valley in this wavelength range (Figure 6), which becomes the obstacle for further improving Jsc. To overcome this inherent drawback of porphyrin dyes, a cosensitizer with complementary absorption may be employed to improve the photovoltaic efficiencies by means of improving the Jsc.20

Figure 8. (a) IPCE action spectra for the DSSCs cosensitized with WS-5. (b) J–V characteristics of the cosensitized DSSCs with WS-5. Considering the fact that the complementarily absorbing dye WS-5 individually demonstrates a high Voc of 791 mV and a high photovoltaic efficiency of 8.38%,38 it was thus employed for cosensitization with XW14 – XW17. The photovoltaic behaviour and the corresponding parameters are shown in Figure 8 and Table 3. Consistent with our expectation, the IPCE valleys for the porphyrin dyes were really filled up, and thus the IPCE curves showed larger values relative to those for the individual porphyrin sensitized cells, with the maximum reaching higher than 90%, resulting in high Jsc values of 18.54–20.30 mA cm-2. The Jsc of 20.30 mA cm-2 achieved for XW17+WS5 is in agreement with that of 20.31 mA cm-2 estimated from the IPCE spectrum (Figure S3). The Voc for a cosensitized solar cell usually lies between those for the individual dyes.23-25 Thus, the cosensitized DSSCs exhibit Voc values of 748–773 mV, obviously higher than those of 700– 734 mV for the individual porphyrin dye sensitized solar cells, but lower than 791 mV for WS-5. As a result of the improved Jsc and Voc, a high efficiency of 10.9% was achieved for XW17+WS-5, which is among the highest efficiencies obtained for DSSCs based on iodine electrolyte.20,46

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DSSCs based on XW17+WS-5 exhibit good photostability, which is beneficial for practical applications.

Electrochemical Impedance Spectroscopy To further understand the photovoltaic behavior of the DSSCs, electrochemical impedance spectroscopy (EIS) was carried out in the dark. The Voc for DSSCs are known to be affected by the charge recombination process and the shift of the TiO2 conduction band, which could be inferred from the chemical capacitance (Cµ).47

Figure 10. Variation of the photovoltaic parameters (Jsc, Voc, FF, and PCE) with aging time for the DSSC device based on XW17+WS-5 under visible-light soaking. CONCLUSIONS

Figure 9. Plots of Cμ (a) and τ (b) versus bias voltage of DSSCs based on XW14 – XW17. As shown in Figure 9a, the Cµ of the individual porphyrin dye sensitized DSSCs are almost identical, indicating the neglectable effects of the difference in chemical capacitance on the Voc. Thus, the dependence of electron lifetimes (τ) on bias voltage is plotted in Figure 9b. In general, a longer electron lifetime implies slower recombination rate at the dye-sensitized TiO2–electrolyte interface.48 At a given bias voltage of 650 mV, the τ lie in the order of XW17 (101 ms) < XW15 (170 ms) ≈ XW14 (190 ms) < XW16 (322 ms), indicative of the decreasing charge recombination rates, which is consistent with the observed increasing Voc of the DSSC devices. The cosensitized DSSCs demonstrate the same trend (Figure S4). These observations indicate that the Voc of all these DSSCs are governed by the charge recombination rates rather than the positions of the TiO2 conduction band. Photostability In addition to high cell efficiencies, the stability is a critical factor for the practical application of DSSCs. Thus, the Jsc, Voc, FF, and PCE values for the XW17 and WS-5cosensitized cells were recorded over a period of 1000 h (Figure 10). After 1000 h of visible-light soaking, the PCE remained at 88% of the initial value, indicating that the

In summary, porphyrin dyes containing a triphenylamine donor have been designed and optimized for developing highly efficient DSSCs. Thus, XW14 exhibits a photovoltaic efficiency of 8.6%. After introducing methoxy or hexyloxy groups into the triphenylamine to suppress the dye aggregation, XW15 and XW16 exhibit improved efficiencies of 8.7% and 9.1%, respectively. After further inserting an auxiliary benzothiadiazole acceptor, XW17 exhibits a much broader absorption spectrum with a striking IPCE onset wavelength of 830 nm, thus achieving a high efficiency of 9.5%. Cosensitization with WS-5 further enhanced the Jsc and Voc. As a result, the cosensitization of XW17 and WS-5 affords an impressive efficiency of 10.9%, which is among the highest efficiencies obtained for DSSCs based on iodine electrolyte. EXPERIMENTAL SECTION Materials and reagents All reagents and solvents were obtained from commercial sources and used without further purification unless otherwise noted. THF was dried over 4 Å molecular sieves, and distilled under nitrogen from sodium benzophenone prior to use. Tetrabutylammonium hexafluorophosphate (TBAPF6) was vacuum-dried for 48 h. The transparent FTO conducting glass (fluorine-doped SnO2, transmission >90% in the visible range, sheet resistance 15Ω/square) and the TiO2 paste was purchased from Geao Science and Educational Co. Ltd. The FTO conducting glass was washed with a detergent solution, deionized water, ethanol, and acetone successively under ultrasonication for 20 min prior to use. Dibromoporphyrin ZnPBr2 were prepared according to the reported procedures.28 Equipments and apparatus 1

H NMR and 13C NMR spectra were obtained using a Bruker AM 400 or 500 MHz spectrometer at 298 K with tetramethylsilane (TMS) as the internal standard. Matrix– assisted laser desorption/ionization time–of–flight mass

6


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spectrometry (MALDI–TOF–MS) was measured using a Shimadzu-Kratos model Axima CFR+ mass spectrometer with dithranol as the matrix. UV-Vis absorption spectra were recorded on a Varian Cary 100 spectrophotometer and fluorescence spectra were recorded on a Varian Cray Eclipse fluorescence spectrophotometer. The cyclic voltammograms of the dyes were obtained in acetonitrile with a Versastat II electrochemical workstation (Princeton Applied Research) using 0.1 M TBAPF6 (Aldrich) as the supporting electrolyte, the sensitizer attached to a nanocrystalline TiO2 film deposited on the conducting FTO glass as the working electrode, a platinum wire as the counter electrode, and a regular calomel electrode in saturated KCl solution as the reference electrode. The scan rate was 100 mV s-1. Photovoltaic measurements were performed by employing an AM 1.5 solar simulator equipped with a 300 W xenon lamp (model no. 91160, Oriel). The power of the simulated light was calibrated to 100 mW cm-2 using a Newport Oriel PV reference cell system (model 91150 V). J–V curves were obtained by applying an external bias to the cell and measuring the generated photocurrent with a model 2400 source meter (Keithley Instruments, Inc. USA). The voltage step and delay time of the photocurrent were 10 mV and 40 ms, respectively. Action spectra of the incident monochromatic photon-to-electron conversion efficiency (IPCE) for the solar cells were obtained with a Newport74125 system (Newport Instruments). The intensity of monochromatic light was measured with a Si detector (Newport-71640). The electrochemical impedance spectroscopy (EIS) measurements of all the DSSCs were performed using a Zahner IM6e Impedance Analyzer (ZAHNER-Elektrik GmbH & CoKG, Kronach, Germany), with the frequency range of 0.1 Hz–100 kHz and the alternative signal of 10 mV. Theoretical Approach The ground state geometries and frontier molecular orbitals of the compounds were computed using the hybrid B3LYP functional42 together with the Los Alamos effective core potential (LANL2DZ) basis set43 for zinc atom and Pople’s 6-31G* basis set44 for lighter atoms. All theoretical calculations were carried out using the Gaussian 09 program package.45 Fabrication of the solar cells The procedure for preparation of TiO2 electrodes and fabrication of the sealed cells for photovoltaic measurements were adapted from that reported by Grätzel and coworkers.49 A screen-printed double layer of TiO2 particles was used as the photoelectrode. The detailed procedure was reported in our previous work.23 The films were then immersed into a 0.2 mM solution of the dyes containing 2 mM chenodeoxycholic acid in a mixture of toluene and ethanol (volume ratio of 1:4) for 10 h at room temperature. For cosensitization, these porphyrin-sensitized films were washed with ethanol, dried in air, and immersed in a solution containing WS-5 (0.3 mM) in a mixture of chloroform

and ethanol (volume ratio of 1 : 1) and kept at 25 °C for 1.5 h. The counter electrode was also prepared according to the procedure reported in our previous work.23 Finally, the DSSCs were assembled, with the electrolyte solution containing 0.1 M LiI, 0.05 M I2, 0.6 M 1-methyl-3-propylimidazolium iodide (PMII), and 0.5 M 4-tertbutylpyridine (TBP) in acetonitrile. Syntheses of the dyes 2a: Under a nitrogen atmosphere, 1a (3.7 g, 22.0 mmol), 1,4-bis(hexyloxy)-2,5-diiodobenzene (14 g, 26.4 mmol), copper(I) iodide (168 mg, 0.9 mmol), trans-1,2cyclohexanediamine (0.7 g, 6.0 mmol), and potassium phosphate (40.0 g, 192.0 mmol) were suspended in absolute 1,4-dioxane (200 mL) and stirred for 48 h at 110 °C. The reaction mixture was suspended in CH2Cl2 and washed with water. The aqueous phase was extracted two times with CH2Cl2 and the combined organic extracts were dried over Na2SO4. The residue was purified by column chromatography on silica gel using petroleum and CH2Cl2 as the eluent to give 2a (3.0 g, yield 24%). 1H NMR (CDCl3, 400 MHz, ppm): δ 0.81 (t, J = 7.2 Hz, 3H), 0.89 (m, J = 7.2 Hz, 3H), 0.96-1.20 (m, 6H), 1.25-1.34 (m, 6H), 1.431.46 (m, 2H), 1.68-1.75 (m, 2H), 3.68 (t, J = 6.4 Hz, 2H), 3.79 (t, J = 6.4 Hz, 2H), 6.64 (s, 1H, phenyl), 6.93 (t, J = 7.2 Hz, 2H, phenyl), 6.98 (d, J = 8.0 Hz, 4H, phenyl), 7.18 (t, J = 8.4 Hz, 4H, phenyl), 7.30 (s, 1H). 13C NMR (CDCl3, 100 MHz): δ 14.06, 22.47, 22.59, 25.26, 25.73, 29.04, 29.11, 31.50, 31.53, 69.47, 70.08, 81.93, 113.86, 121.78, 121.92, 125.20, 128.84, 136.71, 147.44, 150.05, 152.66. HRMS (ESI, m/z): [M+H]+ calcd for C30H39NO2I, 572.2026; found, 572.2038. 2b: It was prepared according to the procedure same as that for 2a, except that 1b (1.26 g, 5.5 mmol) was used instead of 1a. Yield: 462 mg, 13%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.83 (t, J = 6.8 Hz, 3H), 0.89 (t, J = 6.8 Hz, 3H), 1.00-1.05 (m, 2H), 1.07-1.12 (m, 2H), 1.14-1.21 (m, 2H), 1.281.35 (m, 6H), 1.40-1.48 (m, 2H), 1.67-1.74 (m, 2H), 3.68 (t, J = 6.4 Hz, 2H), 3.76 (t, J = 5.2 Hz, 8H), 6.55 (s, 1H, phenyl), 6.74 (d, J = 8.8 Hz, 4H, phenyl), 6.88 (d, J = 8.8 Hz, 4H, phenyl), 7.25 (s, 1H, phenyl). 13C NMR (CDCl3, 100 MHz): δ 14.05, 14.07, 22.47, 22.59, 25.34, 25.73, 29.11, 31.53, 31.55, 55.50, 69.59, 70.01, 80.03, 112.68, 114.18, 123.46, 125.30, 137.94, 141.59, 149.25, 152.62, 154.74. HRMS (ESI, m/z): [M+H]+ calcd for C32H43NO4I, 632.2237; found, 632.2233. 2c: It was prepared according to the procedure same as that for 2c, except that 1c (6.3 g, 17.0 mmol) was used instead of 1a. Yield: 3.6 g, 8%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.82 (t, J = 7.2 Hz, 3H), 0.87-0.92 (m, 9H), 0.991.21 (m, 6H), 1.22-1.34 (m, 14H), 1.39-1.46 (m, 6H), 1.66-1.78 (m, 6H), 3.67 (t, J = 6.4 Hz, 2H), 3.75 (t, J = 6.4 Hz, 2H), 3.89 (t, J = 6.4 Hz, 4H), 6.54 (s, 1H, phenyl), 6.73 (d, J = 8.8 Hz, 4H, phenyl), 6.86 (d, J = 8.8 Hz, 4H, phenyl), 7.24 (s, 1H, phenyl). 13C NMR (CDCl3, 100 MHz): δ 14.06, 14.09, 22.49, 22.59, 22.64, 25.36, 25.74, 25.79, 29.12, 29.39, 31.53, 31.58, 31.65, 68.30, 69.60, 70.00, 79.81, 112.61, 114.80, 115.39, 123.48, 125.30, 127.73, 130.55, 138.08, 141.45, 149.21, 152.61,

7



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154.32. HRMS (ESI, m/z): [M+H]+ calcd for C42H63NO4I, 772.3802; found, 772.3787. 3a: In a three-necked 250 ml-flask, 2a (2.1 g, 3.6 mmol), Pd(PPh3)2Cl2 (63 mg, 0.09 mmol) and CuI (34 mg, 0.18 mmol) were mixed in THF and Et3N (150 mL) under nitrogen. Then trimethylsilylacetylene (432 mg, 4.4 mmol) was added. After stirring at 50 °C for 24 h, the solvent was removed under reduced pressure, and the residue was purified on a silica gel column to give the target compound (900 mg, yield 46%). 1H NMR (CDCl3, 400 MHz, ppm): δ 0.32 (s, 9H), 3.66 (s, 3H, OMe), 3.81 (s, 3H, OMe), 6.96 (s, 1H, phenyl), 7.13 (d, J = 8.4 Hz, 2H, phenyl), 7.25 (s, 1H, phenyl), 7.27 (t, J = 7.6 Hz, 2H, phenyl), 7.39 (t, J = 7.6 Hz, 2H, phenyl), 8.12 (d, J = 7.6 Hz, 2H, phenyl). 3b: It was prepared according to the procedure same as that for 3a, except that 2b (1.9 g, 3.0 mmol) was used instead of 2a. Yield: 1.2 g, 67%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.16 (s, 9H), 0.73-0.80 (m, 6H), 0.92-1.13 (m, 6H), 1.17-1.22 (m, 6H), 1.30-1.47 (m, 2H), 1.60-1.70 (m, 2H), 3.59 (t, J = 6.0 Hz, 2H), 3.67 (s, 6H), 3.70 (d, J = 6.0 Hz, 2H), 6.44 (s, 1H, phenyl), 6.45 (d, J = 8.4 Hz, 4H, phenyl), 6.79 (d, J = 8.8 Hz, 4H, phenyl), 6.85 (s, 1H, phenyl). 3c: It was prepared according to the procedure same as that for 3a, except that 2c (3.6 g, 4.7 mmol) was used instead of 2a. Yield: 3.1 g, 88%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.24 (s, 9H), 0.82 (t, J = 7.2 Hz, 3H), 0.86-0.92 (m, 9H), 0.98-1.19 (m, 6H), 1.25-1.34 (m, 14H), 1.41-1.46 (m, 6H), 1.67-1.78 (m, 6H), 3.67 (t, J = 6.4 Hz, 2H), 3.77 (t, J = 6.4 Hz, 2H), 3.89 (t, J = 6.4 Hz, 4H), 6.51 (s, 1H, phenyl), 6.72 (d, J = 8.8 Hz, 4H, phenyl), 6.85 (d, J = 8.8 Hz, 4H, phenyl), 6.92 (s, 1H, phenyl). 4a: 3a (900 mg, 1.7 mmol), KOH (117 mg, 2.5 mmol), a few drops of methanol and 40 ml THF were mixed in a 100 ml flask and stirred for 30 min at room temperature. Then the organic layer was extracted with CH2Cl2 and dried over Na2SO4. After the solvent was removed under reduced pressure, the residue was purified on a silica gel column to give the target compound (700 mg, yield 90%). 1 H NMR (CDCl3, 400 MHz, ppm): δ 0.81 (t, J = 7.2 Hz, 3H), 0.87 (m, J = 7.2 Hz, 3H), 0.96-1.02 (m, 2H), 1.04-1.20 (m, 4H), 1.23-1.34 (m, 6H), 1.36-1.43 (m, 2H), 3.26 (s, 1H), 3.67 (t, J = 6.4 Hz, 2H), 3.83 (t, J = 6.4 Hz, 2H), 6.65 (s, 1H, phenyl), 6.92-6.96 (m, 2H, phenyl), 6.98-7.00 (m, 5H, phenyl), 7.16-7.21 (m, 4H, phenyl). 13C NMR (CDCl3, 100 MHz): δ 14.03, 14.07, 22.47, 22.57, 25.28, 25.56, 29.03, 29.06, 31.52, 31.55, 69.25, 69.59, 80.22, 80.75, 108.32, 113.76, 119.62, 122.00, 122.26, 128.84, 137.72, 147.51, 148.54, 155.22. HRMS (ESI, m/z): [M+H]+ calcd for C32H39NO2, 470.3059; found, 470.3073. 4b: It was prepared according to the procedure same as that for 4a, except that 3b (1.2 g, 2.0 mmol) was used instead of 3a. Yield: 750 mg, 71%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.81-0.89 (m, 6H), 0.99-1.22 (m, 6H), 1.25-1.33 (m, 8H), 1.36-1.41 (m, 2H), 1.66-1.73 (m, 2H), 3.24 (s, 1H), 3.68 (t, J = 6.4 Hz, 2H), 3.77-3.82 (m, 8H), 6.54 (s, 1H, phenyl), 6.75 (d, J = 8.8 Hz, 4H, phenyl), 6.89 (d, J = 8.8 Hz, 4H,

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phenyl), 6.95 (s, 1H, phenyl). 13C NMR (CDCl3, 100 MHz): δ 14.01, 14.07, 22.47, 22.57, 25.37, 25.56, 29.06, 29.10, 29.71, 30.20, 31.45, 31.55, 31.57, 50.09, 55.48, 69.38, 69.54, 80.33, 80.44, 106.72, 112.30, 114.18, 119.80, 123.89, 138.98, 141.59, 147.54, 154.96, 155.27. HRMS (ESI, m/z): [M+H]+ calcd for C34H44NO4, 530.3270; found, 530.3265. 4c: It was prepared according to the procedure same as that for 4a, except that 3c (3.1 g, 3.8 mmol) was used instead of 3a. Yield: 2.1 g, 81%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.81-0.92 (m, 12H), 1.01-1.99 (m, 8H), 1.25-1.46 (m, 20H), 1.67-1.79 (m, 4H), 3.23 (s, 1H), 3.67 (t, J = 6.4 Hz, 2H), 3.79 (t, J = 6.4 Hz, 2H), 3.89 (t, J = 6.4 Hz, 4H), 6.54 (s, 1H, phenyl), 6.74 (d, J = 8.8 Hz, 4H, phenyl), 6.87 (d, J = 8.8 Hz, 4H, phenyl), 6.95 (s, 1H, phenyl). 13C NMR (CDCl3, 100 MHz): δ 14.03, 14.06, 14.10, 22.50, 22.58, 22.64, 25.39, 25.57, 25.79, 29.07, 29.12, 29.39, 31.56, 31.61, 31.65, 53.44, 68.28, 69.38, 69.51, 80.26, 80.48, 106.54, 112.20, 114.79, 119.79, 123.90, 139.11, 141.44, 147.49, 154.55, 155.27. HRMS (ESI, m/z): [M+H]+ calcd for C44H64NO4, 670.4835; found, 670.4831. 5a: ZnP-Br2 (600 mg, 0.42 mmol), 4a (240 mg, 0.51 mmol), Pd2(dba)3 (202 mg, 0.22 mmol), AsPh3 (302 mg, 0.84 mmol) were placed in a three-necked 500 ml-flask, which was flushed with nitrogen and then charged with dry THF (200 mL) and Et3N (40 mL). The mixture was stirred at 50 °C for 5 h. Then the solvent was removed under reduced pressure, and the residue was dissolved in CH2Cl2 and washed with water, dried over anhydrous sodium sulfate, and evaporated. The residue was purified on a silica gel column. Recrystallization from CH2Cl2/CH3OH gave the target compound (342 mg, yield 45%). 1H NMR (CDCl3, 400 MHz, ppm): δ 0.34-0.65 (m, 36H), 0.75-0.86 (m, 20H), 0.88-1.00 (m, 18H), 1.02-1.25 (m, 28H), 1.29-1.34 (m, 4H), 1.38-1.45 (m, 4H), 1.64-1.71 (m, 2H), 2.07-2.14 (m, 2H), 3.83 (t, J = 6.4 Hz, 8H), 3.90 (t, J = 6.4 Hz, 2H), 4.09 (t, J = 6.4 Hz, 2H), 6.87 (s, 1H, phenyl), 6.97-7.00 (m, 6H, phenyl), 7.12 (d, J = 7.8 Hz, 4H, phenyl), 7.23-7.27 (m, 4H, phenyl), 7.49 (s, 1H, phenyl), 7.68 (t, J = 8.4 Hz, 2H, phenyl), 8.84 (t, J = 5.2 Hz, 4H, pyrrolic), 9.58 (d, J = 4.8 Hz, 2H, pyrrolic), 9.82 (d, J = 4.4 Hz, 2H, pyrrolic). 13C NMR (CDCl3, 100 MHz): δ 14.14, 22.56, 22.68, 25.25, 25.42, 26.14, 28.61, 28.72, 29.06, 29.22, 29.27, 29.34, 29.46, 29.76, 31.64, 31.87, 31.96, 68.71, 69.56, 92.74, 97.33, 100.62, 104.74, 105.28, 110.98, 113.20, 114.94, 118.80, 120.96, 121.92, 122.26, 128.90, 129.87, 131.26, 132.13, 132.49, 136.98, 147.69, 148.88, 149.02, 150.54, 151.30, 152.41, 155.26, 159.94. HRMS (ESI, m/z): [M+H]+ calcd for C112H153BrN5O6Zn, 1807.0296; found, 1807.0290. 5b: It was prepared according to the procedure same as that for 5a, except that 4b (270 mg, 0.51 mmol) was used instead of 4a. Yield: 382 mg, 48%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.39-0.71 (m, 36H), 0.79-0.88 (m, 20H), 0.89-0.97 (m, 18H), 1.04-1.22 (m, 28H), 1.29-1.44 (m, 8H), 1.64-1.71 (m, 2H), 2.05-2.12 (m, 2H), 3.79 (s, 6H), 3.83 (t, J = 6.4 Hz, 8H), 3.90 (t, J = 6.4 Hz, 2H), 4.06 (t, J = 6.4 Hz, 2H), 6.76 (s, 1H, phenyl), 6.80 (d, J = 8.8 Hz, 4H, phenyl), 6.98-7.02 (m, 8H, phenyl), 7.45 (s, 1H, phenyl), 7.68 (t, J =

8


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8.4 Hz, 2H, phenyl), 8.79 (t, J = 6.0 Hz, 4H, pyrrolic), 9.54 (d, J = 4.4 Hz, 2H, pyrrolic), 9.79 (d, J = 4.4 Hz, 2H, pyrrolic). 13C NMR (CDCl3, 100 MHz): δ 14.14, 22.57, 22.69, 25.25, 25.51, 26.16, 28.62, 28.71, 29.06, 29.21, 29.27, 29.34, 29.45, 29.78, 31.70, 31.87, 31.98, 55.53, 68.70, 69.50, 69.69, 93.07, 96.94, 100.99, 104.60, 105.26, 109.43, 111.81, 114.26, 114.96, 119.08, 120.94, 123.85, 129.86, 131.28, 132.08, 132.16, 132.46, 138.29, 141.79, 147.92, 149.04, 150.53, 151.27, 152.38, 154.89, 155.35, 159.95. HRMS (ESI, m/z): [M+H]+ calcd for C114H157BrN5O8Zn, 1867.0507; found, 1867.0501. 5c: It was prepared according to the procedure same as that for 5a, except that 4c (332 mg, 0.51 mmol) was used instead of 4a. Yield: 439 mg, 52%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.36-0.63 (m, 28H), 0.77-0.96 (m, 46H), 1.02-1.25 (m, 34H), 1.33-1.47 (m, 18H), 1.65-1.82 (m, 8H), 2.05-2.10 (m, 2H), 3.83 (t, J = 6.4 Hz, 8H), 3.89 (t, J = 6.4 Hz, 2H), 3.93 (t, J = 6.4 Hz, 4H), 4.06 (t, J = 6.4 Hz, 2H), 6.76 (s, 1H, phenyl), 6.80 (d, J = 8.8 Hz, 4H, phenyl), 6.977.01 (m, 8H, phenyl), 7.45 (s, 1H, phenyl), 7.68 (t, J = 8.4 Hz, 2H, phenyl), 8.82 (q, J = 2.4 Hz, 4H, pyrrolic), 9.56 (d, J = 4.4 Hz, 2H, pyrrolic), 9.81 (d, J = 4.4 Hz, 2H, pyrrolic). 13 C NMR (CDCl3, 100 MHz): δ 14.08, 14.14, 22.58, 22.66, 22.68, 25.24, 25.53, 25.82, 26.16, 28.61, 28.71, 29.05, 29.21, 29.26, 29.33, 29.45, 29.73, 29.77, 31.68, 31.73, 31.87, 31.97, 68.35, 68.70, 69.70, 93.11, 96.90, 101.02, 104.56, 105.27, 109.24, 111.71, 114.88, 119.09, 120.97, 123.87, 129.84, 131.28, 132.05, 132.13, 132.43, 138.42, 141.64, 147.85, 149.03, 150.51, 151.24, 152.37, 154.50, 155.34, 159.95. HRMS (ESI, m/z): [M+H]+ calcd for C124H177BrN5O8Zn, 2007.2072; found, 2007.2066. 6a: 5a (158 mg, 0.09 mmol), methyl 4-ethynylbenzoate (42 mg, 0.26 mmol), Pd(PPh3)4 (15 mg, 0.01 mmol), CuI (2.5 mg, 0.01 mmol) were placed in a three-necked 500 ml-flask, flushed with nitrogen and then charged with dry THF (150 mL) and Et3N (15 mL). The mixture was stirred at 55 °C for 4.5 h. Then, the solvent was removed under reduced pressure, and the residue was dissolved in CH2Cl2 and washed with water, dried over anhydrous sodium sulfate, and evaporated. The residue was purified on a silica gel column. Recrystallization from CH2Cl2/CH3OH gave the target compound (51 mg, 31%). 1H NMR (CDCl3, 400 MHz, ppm): δ 0.29-0.57 (m, 36H), 0.66-0.73 (m, 20H), 0.75-0.84 (m, 18H), 0.86-1.00 (m, 28H), 1.02-1.13 (m, 4H), 1.29-1.36 (m, 4H), 1.57-1.64 (m, 2H), 2.00-2.07 (m, 2H), 3.77 (t, J = 6.4 Hz, 8H), 3.83 (t, J = 6.4 Hz, 2H), 3.89 (s, 3H), 4.02 (t, J = 6.4 Hz, 2H), 6.80 (s, 1H, phenyl), 6.90-6.94 (m, 6H, phenyl), 7.05 (d, J = 7.8 Hz, 4H, phenyl), 7.16-7.20 (m, 4H, phenyl), 7.42 (s, 1H, phenyl), 7.62 (t, J = 8.4 Hz, 2H, phenyl), 7.89 (d, J = 8.4 Hz, 2H, phenyl), 8.04 (d, J = 8.4 Hz, 2H, phenyl), 8.75 (d, J = 4.4 Hz, 2H, pyrrolic), 8.80 (d, J = 4.8 Hz, 2H, pyrrolic), 9.55 (d, J = 4.4 Hz, 2H, pyrrolic), 9.74 (d, J = 4.4 Hz, 2H, pyrrolic). 13C NMR (CDCl3, 100 MHz): δ 14.07, 14.09, 14.12, 22.52, 22.62, 22.66, 25.25, 25.39, 26.11, 28.60, 28.69, 29.05, 29.19, 29.21, 29.31, 29.42, 29.69, 29.73, 31.61, 31.81, 31.93, 52.17, 68.68, 69.51, 93.16, 94.74, 96.63, 97.33, 98.93, 99.94, 101.99, 105.22, 110.82, 113.10, 115.50, 118.81, 120.85, 121.91, 122.25, 128.75, 128.87, 129.14,

129.56, 129.84, 130.30, 131.00, 131.16, 131.62, 132.05, 137.07, 147.65, 148.82, 150.48, 150.66, 151.60, 151.71, 155.29, 159.91, 166.53. HRMS (ESI, m/z): [M+H]+ calcd for C122H160N5O8Zn, 1887.1558; found, 1887.1553. 6b: It was prepared according to the procedure same as that for 6a, except that 5b (100 mg, 0.05 mmol) was used instead of 5a. Yield: 88 mg, 85%. 1H NMR (CDCl3, 400 MHz, ppm): 0.38-0.63 (m, 36H), 0.73-0.91 (m, 38H), 0.941.25 (m, 28H), 1.29-1.42 (m, 8H), 1.64-1.71 (m, 2H), 2.06-2.13 (m, 2H), 3.79 (s, 6H), 3.84 (t, J = 6.4 Hz, 8H), 3.90 (t, J = 6.4 Hz, 2H), 3.97 (s, 3H), 4.06 (t, J = 6.4 Hz, 2H), 6.76 (s, 1H, phenyl), 6.80 (d, J = 8.8 Hz, 4H, phenyl), 6.99-7.02 (m, 8H, phenyl), 7.46 (s, 1H, phenyl), 7.69 (t, J = 8.4 Hz, 2H, phenyl), 7.99 (d, J = 8.0 Hz, 2H, phenyl), 8.14 (d, J = 8.0 Hz, 2H, phenyl), 8.81 (d, J = 4.4 Hz, 2H, pyrrolic), 8.87 (d, J = 4.8 Hz, 2H, pyrrolic), 9.62 (d, J = 4.8 Hz, 2H, pyrrolic), 9.80 (d, J = 4.8 Hz, 2H, pyrrolic). 13C NMR (CDCl3, 100 MHz): δ 14.14, 14.18, 14.20, 22.60, 22.69, 22.75, 25.34, 25.55, 26.22, 28.70, 28.78, 29.13, 29.27, 29.29, 29.38, 29.49, 29.77, 29.83, 31.73, 31.89, 32.04, 52.17, 55.52, 68.75, 69.52, 69.71, 93.54, 94.73, 96.73, 97.11, 98.94, 102.35, 105.27, 109.37, 111.77, 114.30, 115.54, 119.16, 120.95, 123.88, 128.59, 129.05, 129.45, 129.89, 130.36, 130.89, 131.22, 131.62, 132.09, 138.43, 141.81, 147.92, 150.50, 150.69, 151.64, 151.82, 154.88, 155.45, 160.00, 166.43. [M+H]+ calcd for C124H164N5O10Zn, 1947.1770; found, 1947.1764. 6c: It was prepared according to the procedure same as that for 6a, except that 5c (150 mg, 0.07 mmol) was used instead of 5a. Yield: 43 mg, 27%. 1H NMR (CDCl3, 400 MHz, ppm): 0.38-0.63 (m, 28H), 0.73-0.95 (m, 46H), 0.971.25 (m, 34H), 1.28-1.47 (m, 18H), 1.66-1.82 (m, 8H), 2.062.11 (m, 2H), 3.84 (t, J = 6.4 Hz, 8H), 3.90 (t, J = 6.4 Hz, 2H), 3.94 (t, J = 6.4 Hz, 4H), 3.97 (s, 3H), 4.06 (t, J = 6.4 Hz, 2H), 6.76 (s, 1H, phenyl), 6.80 (d, J = 8.8 Hz, 4H, phenyl), 7.01 (d, J = 8.8 Hz, 8H, phenyl), 7.45 (s, 1H, phenyl), 7.69 (t, J = 8.4 Hz, 2H, phenyl), 7.98 (d, J = 8.0 Hz, 2H, phenyl), 8.14 (d, J = 8.4 Hz, 2H, phenyl), 8.82 (d, J = 4.4 Hz, 2H, pyrrolic), 8.86 (d, J = 4.4 Hz, 2H, pyrrolic), 9.62 (d, J = 4.8 Hz, 2H, pyrrolic), 9.81 (d, J = 4.4 Hz, 2H, pyrrolic). 13C NMR (CDCl3, 100 MHz): δ 14.10, 14.12, 14.17, 22.60, 22.67, 22.72, 25.29, 25.54, 25.84, 26.19, 28.65, 28.74, 29.10, 29.24, 29.27, 29.36, 29.45, 29.47, 29.75, 29.79, 31.69, 31.75, 31.87, 32.00, 52.23, 68.36, 68.73, 69.49, 69.71, 93.60, 94.73, 96.76, 97.00, 98.78, 102.44, 105.27, 109.13, 111.65, 114.90, 115.50, 119.14, 120.93, 123.92, 128.20, 128.26, 128.32, 128.83, 129.29, 129.66, 129.86, 130.28, 131.09, 131.22, 131.31, 131.59, 132.09, 135.09, 135.14, 135.19, 138.56, 141.64, 147.83, 150.47, 150.67, 151.61, 151.79, 154.54, 155.43, 159.96, 166.63. HRMS (ESI, m/z): [M+H]+ calcd for C134H184N5O10Zn, 2087.3335; found, 2087.3329. 6d: It was prepared according to the procedure same as that for 6c, except that methyl 4-(7ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoate (21 mg, 0.06 mmol) were used instead of methyl 4ethynylbenzoate. Yield: 45 mg, 67%. 1H NMR (CDCl3, 400 MHz, ppm): δ 0.42-0.64 (m, 28H), 0.73-1.06 (m, 46H), 1.09-1.37 (m, 34H), 1.40-1.47 (m, 18H), 1.65-1.82 (m, 8H),

9



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2.06-2.13 (m, 2H), 3.86 (t, J = 6.4 Hz, 8H), 3.90 (t, J = 6.4 Hz, 2H), 3.94 (t, J = 6.4 Hz, 4H), 3.97 (s, 3H), 4.06 (t, J = 6.4 Hz, 2H), 6.76 (s, 1H, phenyl), 6.80 (d, J = 8.8 Hz, 4H, phenyl), 6.99-7.02 (m, 8H, phenyl), 7.45 (s, 1H, phenyl), 7.70 (t, J = 8.4 Hz, 2H, phenyl), 7.84 (d, J = 7.2 Hz, 1H, phenyl), 8.06 (d, J = 8.4 Hz, 2H, phenyl), 8.15 (d, J = 8.0 Hz, 2H, phenyl), 8.22 (d, J = 7.2 Hz, 1H, phenyl), 8.82 (d, J = 4.8 Hz, 2H, pyrrolic), 8.91 (d, J = 4.4 Hz, 2H, pyrrolic), 9.79 (d, J = 4.4 Hz, 2H, pyrrolic), 9.97 (d, J = 4.4 Hz, 2H, pyrrolic). 13C NMR (CDCl3, 100 MHz): δ 14.07, 14.15, 22.57, 22.61, 22.64, 22.70, 25.29, 25.51, 25.81, 26.17, 28.65, 28.74, 29.09, 29.21, 29.32, 29.42, 29.71, 29.77, 31.66, 31.72, 31.80, 31.98, 52.20, 68.32, 68.71, 69.44, 69.67, 92.25, 93.62, 96.99, 98.74, 101.77, 102.60, 105.21, 109.07, 111.55, 114.85, 115.65, 118.27, 119.10, 120.89, 123.89, 128.20, 128.66, 129.34, 129.54, 129.80, 130.73, 130.87, 131.18, 131.46, 132.28, 138.52, 141.01, 141.61, 147.78, 150.48, 150.65, 151.46, 152.10, 152.88, 154.51, 155.40, 155.95, 159.95, 166.73. HRMS (ESI, m/z): [M+H]+ calcd for C140H186N7O10SZn, 2221.3279; found, 2221.3273. XW14: A mixture of the porphyrin carboxylate 6a (51 mg, 0.027 mmol) and LiOH•H2O (45 mg, 1.08 mmol) in THF (30 mL) and H2O (2 mL) was refluxed for 12 h under nitrogen. Then, the solvent was removed in vacuo. The residue was dissolved in THF and the precipitate was filtered off. The filtrate was concentrated in vacuo to afford the crude product, which was purified by column chromatography on silica gel to give the product as a green powder (43 mg, yield 84 %). 1H NMR (CDCl3 : DMSO-d6 = 1 : 2, 400 MHz, ppm): δ 0.29-0.41 (m, 8H), 0.46-0.63 (m, 8H), 0.74-0.86 (m, 26H), 0.87-1.09 (m, 42H), 1.11-1.18 (m, 10H), 1.35-1.46 (m, 6H), 1.68-1.75 (m, 2H), 2.06-2.11 (m, 2H), 3.87 (t, J = 6.4 Hz, 8H), 3.94 (t, J = 6.0 Hz, 2H), 4.08 (t, J = 6.0 Hz, 2H), 6.88 (s, 1H, phenyl), 6.98 (t, J = 7.2 Hz, 2H, phenyl), 7.02-7.17 (m, 6H, phenyl), 7.25 (t, J = 7.4 Hz, 4H, phenyl), 7.55 (s, 1H, phenyl), 7.71 (t, J = 8.0 Hz, 2H, phenyl), 8.08 (d, J = 7.2 Hz, 2H, phenyl), 8.16 (d, J = 8.0 Hz, 2H, phenyl), 8.21-8.24 (m, 2H, phenyl), 8.66 (d, J = 4.4 Hz, 2H, pyrrolic), 8.70 (d, J = 4.8 Hz, 2H, pyrrolic), 9.53 (d, J = 4.8 Hz, 2H, pyrrolic), 9.71 (d, J = 4.4 Hz, 2H, pyrrolic), 13.00 (s, 1H, COOH). HRMS (ESI, m/z): [M+Na]+ calcd for C121H157N5NaO8Zn, 1895.1221; found, 1895.1216. XW15: It was prepared according to the procedure same as that for XW14, except that 6b (88 mg, 0.045 mmol) was used instead of 6a. Yield: 80 mg, 92%. 1H NMR (CDCl3 : DMSO-d6 = 1 : 2, 400 MHz, ppm): δ 0.27-0.40 (m, 10H), 0.44-0.62 (m, 19H), 0.74-0.80 (m, 12H), 0.83-1.24 (m, 62H), 1.30-1.43 (m, 8H), 1.66-1.74 (m, 2H), 2.03-2.10 (m, 2H), 3.74 (s, 6H), 3.86 (t, J = 6.4 Hz, 8H), 3.92 (t, J = 6.4 Hz, 2H), 4.03 (t, J = 6.4 Hz, 2H), 6.74 (s, 1H, phenyl), 6.82 (d, J = 8.8 Hz, 4H, phenyl), 6.92 (d, J = 8.8 Hz, 4H, phenyl), 7.06 (d, , J = 8.4 Hz, 4H, phenyl), 7.48 (s, 1H, phenyl), 7.70 (t, J = 8.4 Hz, 2H, phenyl), 8.08 (d, J = 8.0 Hz, 2H, phenyl), 8.16 (d, J = 8.4 Hz, 2H, phenyl), 8.83 (d, J = 4.4 Hz, 2H, pyrrolic), 8.69 (d, J = 4.4 Hz, 2H, pyrrolic), 9.52 (d, J = 4.4 Hz, 2H, pyrrolic), 9.68 (d, J = 4.4 Hz, 2H, pyrrolic), 13.01 (s, 1H, COOH). [M+H]+ calcd for C123H162N5O10Zn, 1933.1613; found, 1933.1608.

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XW16: It was prepared according to the procedure same as that for XW14, except that 6c (45 mg, 0.022 mmol) was used instead of 6a. Yield: 40 mg, 87%. 1H NMR (CDCl3 : DMSO-d6 = 1 : 2, 400 MHz, ppm): δ 0.30-0.55 (m, 28H), 0.73-0.94 (m, 46H), 1.04-1.23 (m, 34H), 1.31-1.42 (m, 18H), 1.67-1.74 (m, 8H), 2.02-2.07 (m, 2H), 3.86-3.92 (m, 14H), 4.01 (t, J = 5.2 Hz, 2H), 6.73 (s, 1H, phenyl), 6.80 (d, J = 9.2 Hz, 4H, phenyl), 6.89 (d, J = 8.8 Hz, 4H, phenyl), 7.07 (d, J = 8.8 Hz, 4H, phenyl), 7.48 (s, 1H, phenyl), 7.70 (t, J = 8.4 Hz, 2H, phenyl), 8.08 (d, J = 8.0 Hz, 2H, phenyl), 8.15 (d, J = 8.4 Hz, 2H, phenyl), 8.62 (d, J = 4.4 Hz, 2H, pyrrolic), 8.69 (d, J = 4.4 Hz, 2H, pyrrolic), 9.52 (d, J = 4.4 Hz, 2H, pyrrolic), 9.68 (d, J = 4.4 Hz, 2H, pyrrolic), 13.06 (s, 1H, COOH). HRMS (ESI, m/z): [M+Na]+ calcd for C133H181N5NaO10Zn, 2095.2998; found, 2095.2992. XW17: It was prepared according to the procedure same as that for XW14, except that 6d (45 mg, 0.02 mmol) was used instead of 6a. Yield: 39 mg, 86%. 1H NMR (CDCl3 : DMSO-d6 = 1 : 2, 400 MHz, ppm): δ 0.32-0.58 (m, 28H), 0.71-0.91 (m, 46H), 0.97-1.24 (m, 34H), 1.31-1.45 (m, 20H), 1.68-1.73 (m, 6H), 2.03-2.09 (m, 2H), 3.86-3.92 (m, 14H), 4.02-4.06 (m, 2H), 6.73 (s, 1H, phenyl), 6.80 (d, J = 9.2 Hz, 4H, phenyl), 6.89 (d, J = 9.2 Hz, 4H, phenyl), 7.07 (d, J = 8.4 Hz, 4H, phenyl), 7.46 (s, 1H, phenyl), 7.70 (t, J = 8.4 Hz, 2H, phenyl), 8.14 (d, J = 7.6 Hz, 1H, phenyl), 8.17 (d, J = 8.4 Hz, 2H, phenyl), 8.25 (d, J = 8.0 Hz, 2H, phenyl), 8.39 (d, J = 7.6 Hz, 1H, phenyl), 8.64 (d, J = 4.4 Hz, 2H, pyrrolic), 8.75 (d, J = 4.4 Hz, 2H, pyrrolic), 9.67 (d, J = 4.4 Hz, 2H, pyrrolic), 9.88 (d, J = 4.4 Hz, 2H, pyrrolic), 12.99 (s, 1H, COOH). HRMS (ESI, m/z): [M+Na]+ calcd for C139H183N7NaO10SZn, 2229.2936; found, 2229.2931.

ASSOCIATED CONTENT Supporting Information Available: Characterization data for the compounds and additional figures were included in the Supporting Information. These materials are available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *[email protected]

Notes The authors declare no competing financial interests.

ACKNOWLEDGMENT This work was supported by the Science Fund for Creative Research Groups (21421004), NSFC/China (21472047, 91227201), and the Oriental Scholarship.

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Table of Contents

13


Porphyrins Containing a Triphenylamine Donor and up to Eight Alkoxy

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