Synthesis and property study of phthalocyanine tetraimides as solution processable electron acceptors

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Synthesis and property study of phthalocyanine tetraimides as solution processable electron acceptors Xiaohong Zhao a, Xiaoshuai Huang a, Ming Hu a, Wenqiang Chai c, Zhongyi Yuan a, *, Xia Liu a, Yu Hu a, Chunsheng Cai a, Yiwang Chen a, b, ** a b c

College of Chemistry/ Institute of Polymers and Energy Chemistry (IPEC), Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China Institute of Advanced Scientific Research, Jiangxi Normal University, 99 Ziyang Avenue, Nanchang, 330022, China Ji An Sanjiang Microfiber Nonwoven co., ltd., Ji an, Jiangxi, 343100, China

A B S T R A C T

Soluble phthalocyanine tetraimides (PcTIs) with hydrophobic side chains were designed and synthesized via three routes. Their absorption, fluorescence, electro­ chemistry, stability, charge mobility, and geometries were investigated. These planar conjugation compounds with intense absorption in 550–850 nm, deep lowest unoccupied molecular orbitals of 3.92 to 3.98 eV, decomposition temperature higher than 400 � C, and highest electron mobility of 4.88 � 10 4 cm2 V 1 s 1 (SCLC) were excellent solution processable acceptors. Bulk heterojunction solar cells based on acceptor CuPcTI-C11 reached a power conversion efficiency of 1.17% which is the highest value among phthalocyanine derivatives.

1. Introduction Phthalocyanines (Pcs) with large disc conjugation have shown promising applications as semiconductors in fields such as solar cells [1], field-effect transistors [2], and non-linear optical materials [3]. Unsubstituted Pcs with strong intermolecular π-π stacking have poor solubility in organic solvents, which makes purification and low cost solution processing difficult [4]. Pcs substituted by regular alkyl or phenyl groups could be soluble electron donors [5], however they typically possess high lowest unoccupied molecular orbital (LUMO) energy levels of 3.5 eV [6], rendering them unsuitable for electron acceptors. Electron acceptors which transport electrons are essential in organic semiconductors [7]. High performance acceptors are more scarce than their donor counterparts. Excellent acceptors with different structures and properties are badly required to meet their various applications [8]. To modify them towards acceptors, electron-withdrawing groups such as F, Cl have been introduced to conjugated cores of Pcs, through which their LUMO energy levels were lowered by 1.3 eV [9]. However, these electron acceptors with limited solubility were processed only by com­ plex vacuum vapor deposition. Thus transforming Pcs into solution processable acceptors deserves intense research. Khaulah et al. [10] directly used tetraphenoxy substituted metal phthalocyanine (structure

was shown in Fig. S1) as acceptor in BHJOSCs, and a PCE of 1.09% was obtained. However, VOPcPhO with high LUMO energy levels of 3.3 eV matches with few donors; meanwhile isomer mixture of VOPcPhO which can not be separated were adopted as acceptors, making its further applications limited. Imide groups with high stability and strong electron-withdrawing groups have been used to construct excellent acceptors [11]. In our recent work, three imide groups were fused with subphthalocyanine (SubPc) cores, and SubPc donors were transformed into solution pro­ cessable acceptors successfully [12]. Electron mobility of target accep­ tors was up to 10 5 cm2 V 1 s 1, and they showed promising applications in organic solar cells. In this work, we are interested in imide substituted Pcs. To acquire water soluble dyes, bulky hydrophilic imide groups have been introduced to Pcs [13], these hydrotropic molecules were unsuit­ able for semiconductors, only absorption of these compounds was re­ ported, and more properties of this type of molecule deserve intense study. Herein, Pcs was substituted with four hydrophobic imide groups, and phthalocyanine tetraimides (PcTIs) with different metals and side chains as promising acceptors were obtained. Their absorption, fluo­ rescence, electrochemistry, stability, and charge transport were inves­ tigated. Pure key intermediate Pc tetraanhydride (PcTA) which could afford PcTIs with different was obtained effectively. Solubility and

* Corresponding author. ** Corresponding author. College of Chemistry/ Institute of Polymers and Energy Chemistry (IPEC), Nanchang University, 999 Xuefu Avenue, Nanchang, 330031, China. E-mail addresses: [email protected] (Z. Yuan), [email protected] (Y. Chen). https://doi.org/10.1016/j.dyepig.2019.107980 Received 20 September 2019; Received in revised form 16 October 2019; Accepted 16 October 2019 Available online 18 October 2019 0143-7208/© 2019 Elsevier Ltd. All rights reserved.

Please cite this article as: Xiaohong Zhao, Dyes and Pigments, https://doi.org/10.1016/j.dyepig.2019.107980

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crystalline of target compounds could be adjusted conveniently by groups attached at the imide N atom. BHJOSCs based on acceptor CuPcTI-C11 showed PCE of 1.17% which is the highest among photo­ voltaic devices with Pc derivatives as acceptors. In the literature [14], as shown in Scheme 1, PcTIs were synthesized by two routes: 1) condensation through key intermediate Pc tetraan­ hydride (PcTA) which can not be purified, making isolation in the next step difficult (Route A); 2) direct cyclization of dicyano compounds in the presence of metal salts (Route B), only certain metals are suitable for the method. In this work, to obtain facile synthetic routes, three different methods which are applicable to different conditions were used and compared. We obtained target compounds via three different methods, as shown in Scheme 2. In route I (blue arrow), H2PcTI which can com­ plex with many metals was afforded. In route II (red arrow), pure PcTA was obtained, and its transformation into PcTIs went smoothly. In route III (black arrow), pure ZnPcTA which could lead to ZnPcTIs with different side chains was obtained. As shown in Scheme 2, 4,5-dicyanophthalimides (4) [12], 4,5-dibro­ modibutylphthalate (6), and 4,5-dicyanodibutylphthalonitrile (7) were synthesized according to literature methods [15]. PcTIs were synthe­ sized in three ways of route I, II, and III (in blue, red, and black arrows respectively). In route I: PcTIs were synthesized in two steps and PcTIs were syn­ thesized by coordination of H2PcTIs with corresponding metal salt in DMF in yield of 96–98%. Compounds H2PcTIs were readily obtained by cyclyzation of 4 in yield of 27–30%. Notably, H2PcTIs could complex with different metals to obtain various PcTIs with different central metals. Route I, route II, and route III were in blue, red, and black arrows respectively. (i) CuCN, KI, DMF, reflux, 4.5 h, 67% (ii) DBU, n-butanol, 140 � C, 4 h, 29%; (iii) metal salt, DMF, 140 � C, 4 h, 96%; (iv) n-butanol, THF, KOH, 60 � C, 24 h, 91%; (v), (viii) acetic anhydride, reflux, 10 h, 98%; (vi), (ix) NMP, 2,6-diisoprophylphenyl, 190 � C, 12 h, 48% and 38.4%; (vii) n-butanol, THF, KOH, 90 � C, 48 h, 41%; (x) DBU, n-hexanol, reflux, 4 h, 30% or DBU, DMEA, 150 � C, 3 h, 27%; (ix) metal salt, DMF, 140 � C, 4 h, 96–98%. In route II, key intermediate (H2PcTA) which could lead to H2PcTIs with different side chains was obtained. H2PcTIs could be synthesized by condensation of H2PcTA with corresponding amine. Cyclization of 7

afforded 8 in yield of 31%. Hydrolysis of 8 with KOH lead to 11 in yield of 41%. Dehydration of 11 in refluxing acetic anhydride afforded H2PcTA in quantitative yield. In route III, pure intermediate (ZnPcTA) which could lead to ZnPcTIs with different side chains was readily obtained. Hydrolysis of 9 with KOH in n-butanol/THF at 60 � C afforded 10 in yield of 91%. All the new compounds 8, 9, H2PcTI-Ph, H2PcTI-C11, ZnPcTI-Ph, CuPcTI-Ph, CuPcTI-C11 were characterized clearly by 1H NMR, 13C NMR, and HRMS. Compound 10 and 11 with limited solubility were characterized by 1H NMR and HRMS. PcTA with poor solubility was characterized by HRMS only. CuPcTIs with paramagnetic Cu2þ, only 1H NMR was obtained. Compound CuPcTI-C11 with bulky 2-pentylhexyl alkyl chains shows excellent solubility (higher than 20 mg/mL) in chlorobenzene, chloroform, and THF, making it solution processable acceptor. The other two compounds with lower solubility (ca. 7 mg/mL in chlorobenzene) because of strong molecular aggregation. Stability is significant for applications of semiconductors [16]. In this work, thermostability and photostability of PcTIs were measured. As shown in Fig. S3, all the compounds keep constant weight in the air below 400 � C, and 5% weight loss temperature of ZnPcTI-Ph, CuPcTI-Ph were higher than 450 � C, indicating their excellent thermostability. 5% Weight loss temperature of CuPcTI-C11 was about 30 � C lower than those of the other two compounds, reflecting better thermostability of phenyl substituted metal PcTIs than alkyl substituted ones. Photo­ stability of PcTIs was measured by illuminating their dilute THF solu­ tions (10 5 M) under the illumination of AM 1.5 G, 100 mW cm 2. As shown in Fig. S4, absorption spectra of CuPcTI-Ph and CuPcTI-C11 remain almost unchanged after 8 h irradiation, suggesting their good stability under solar light. Maximum absorption of ZnPcTI-Ph solution decrease by 25% after illumination for 8 h, indicating much better photostability of copper complexes. Excellent thermostability and pho­ tostability are favourable for their applications in stable photoelectronic devices. Solution and film absorption of three compounds were shown in Fig. 1, and corresponding optical parameters were summarized in Table 1. Three PcTIs with maximum absorption around 690 nm show similar solution profile, indicating little influence of metals and side chains on their ground electronic states. Compared with unsubstituted CuPc and ZnPc [17], maximum absorption of CuPcTI and ZnPcTI

Scheme 1. Synthesis of Phthalocyanine Tetraimides in literature. 2

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Scheme 2. Synthesis of Phthalocyanine Tetraimides.

Fig. 1. Absorption of PcTIs (a) in THF (10

6

cm 1)

M) and (b) in solid state.

Table 1 Optical and electrochemical data of PcTIs. CuPcTI-C11 CuPcTI-Ph ZnPcTI-Ph a b c d e f g

λmaxa (nm)

ε/103 (M

688 690 694

325 299 353

1

λcal max (nm)

λem (nm)b

Φf (%)c

Τ (ns)d

e Eopt g (eV)

664 664 672

694 696 710

2.9 3.4 11.9

2.8 4.6 4.1

1.62 1.58 1.47

LUMO (eV)f 3.94 3.92 3.98

HOMO (eV)g 5.56 5.50 5.45

Maximum absorption in THF. Emission was measured in THF. Fluorescence quantum yield was determined with the standard N, N’ -di (2, 6-isopropylphenyl)-perylene diimides (Φf ¼ 1); [21] Fluorescence lifetime was measured in THF. Estimated based on the film absorption onset. Measured by cyclic voltammetry, ELUMO ¼ 4.8 – Ered 1/2 (vs. Fc/Fcþ) (eV). EHOMO is calculated as ELUMO – Eopt g .

353000 M 1 cm 1, which is much higher than those of unsubstituted Pcs (146600 M 1 cm 1) [18], because bulky 2,6-bis(isopropyl)phenyl groups prevent serious intermolecular aggregation which decreases

red-shifted by 13 and 22 nm, respectively, indicating serious influence of imide groups on the electronic structures of conjugated cores. Maximum extinction coefficients (εmax) of ZnPcTI-Ph at 694 nm is up to 3

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εmax of unsubstituted ones. The other two compounds also have high εmax above 299 000 M 1 cm 1. Solid-state absorption maximum of PcTIs

Compounds with 2,6-diisopropylaniline alkyl chains show electron mobility more than 100 times than that of 2-pentylhexyl substituted Pc, indicating serious influence of side chains on their charge transfer. Due to the poor solubility of CuPcTI-Ph and ZnPcTI-Ph, only mobility of PFBZ:CuPcTI-C11 blend film was measured. The hole mobility (μh) and electron mobility were calculated to be 1.91 � 10 4 cm2 V 1 s 1 and 3.57 � 10 6 cm2 V 1 s 1, respectively. The blend films have relatively balanced charge mobility with μh/μe of 53.5, which is favor for OSCs. In summary, PcTIs as acceptors were designed and synthesized. Their low-lying LUMO energy levels, adjustable solubility, strong absorption, higher thermal stability, and appropriate electron mobility made them potential soluble electron acceptors. Side chains and central metals exert significant effects upon their solubility, electron mobility, and photo­ voltaic application. Preliminary research shows that PcTIs are promising acceptors in BHJOSCs. With further molecular optimization and morphology regulation, more and better applications are expected.

redshift compared to their solution results, reflecting their serious ag­ gregation in the solid state. Cut off wavelength of ZnPcTI-Ph film ab­ sorption was up to 848 nm, red-shifted by 122 nm compared with its solution results, which indicates their strong intermolecular interaction in solid state. Cut off wavelength of CuPcTI-C11 and CuPcTI-Ph film absorption 765 nm, 785 nm shorter than that of ZnPcTI-Ph, reflecting serious effect of metals on their aggregation. Broad solid absorptions grantee them wide response range as photosensitizes. Emission spectra of three compounds in THF were shown in Fig. S5, and corresponding data was summarized in Table 1. ZnPcTI-Ph with quantum yield of 11.9% inherit strong fluorescence characters of ZnPc family [17b]. Quantum yield of CuPcTI (2.9–3.4%) were much higher than those of unsubstituted CuPcs (<0.01%) [19], because bulky side groups can prevent fluorescence quenching in solution. Three com­ pounds have similar emission profiles with emission peaks amid 708–712 nm and Stokes shifts around 18 nm [20]. The fluorescence decay curves were shown in Fig. S6 with the lifetimes of 2.8–4.6 ns. LUMO energy levels of PcTIs were measured with cyclic voltammetry (CV) method. The estimated LUMO energy levels were 3.92 to 3.98 eV (Table 1) which is similar as excellent organic acceptors PC61BM ( 3.91 eV) [22]. Their LUMO energy levels are 0.42–0.48 eV lower than that of unsubstituted Pcs, reflecting strong electron-withdrawing properties of imide groups. Geometric configuration, absorption, and band gaps of three accep­ tors were simulated by density functional theory (DFT) method with PBEPBE/LanL2dZ/6-311G (d, p) level of Gaussian 09 program [23]. The results were shown in Table 1 and Fig. S8. Three acceptors display planar geometries. Calculated maximum absorption (λcal max) was amid 664–672 nm which is close to experimental values (688–694 nm). Theoretical band gaps (1.37 eV) were close to the experiment results (1.47–1.62 eV). Matched theoretical and experimental results indicate reliability of the theoretical method. To investigate the photovoltaic properties of those acceptors in BHJOSCs, an inverted devices architecture of ITO/ZnO (30 nm)/donor: acceptor/MoO3 (7 nm)/Ag (100 nm) was used [24]. PFBZ was selected as the donor due to their matched energy levels and complementary absorption [25]. The optimized blending ratio of the donor and acceptor was 1:2 (Table S1). The current density voltage (J V) curves of the optimized devices based on PFBZ:CuPcTI-C11 were shown in Fig. 2a. Their photovoltaic parameters were summarized in Table S2. Compound CuPcTI-C11 shown the highest PCE of 1.17%, with Voc of 0.55 V, Jsc of 5.28 mA cm 2, and FF of 40.12%. That is the highest value among phthalocyanine derivatives in BHJOSCs. In OSCs, space-charge limited current (SCLC) method [26], reflecting the carrier migration in vertical direction, was used to evaluate charge mobility. As shown in Fig. 2b, the electron mobility (μe) of the acceptor films was calculated to be 1.1 � 10 6 cm2 V 1 s 1, 4 2 1 1 4 2 3.44 � 10 cm V s , and 4.88 � 10 cm V 1 s 1, respectively.

2. Experimental section General Experimental methods: All materials and chemicals were obtained from commercial resources. 1H NMR and 13C NMR spectra were measured with a nuclear magnetic resonance (NMR) spectrometer. The UV–vis spectra were measured with PerkinElmer Lambda 750 spectrophotometer. An electrochemical analyzer with three-electrode system was used to measure the cyclic voltammetry (CV) (working electrode: glassy carbon, reference electrode: Ag/Agþ, auxiliary elec­ trode: Pt wire, internal standard: ferrocene, and electrolyte: tetrabuty­ lammonium hexafluorophosphate (Bu4NPF6) [27]. Gaussian 09 program [28] was used to optimize all structure of acceptors. The current-voltage characteristics of organic solar cells were measured with Keithley 2400 Source Meter of simulated solar light (Abet Solar Simu­ lator Sun 2000, 100 mW cm2, AM 1.5 G). Synthesis of 7 [14a]. A mixture of 6 (5.80 g, 13.3 mmol), CuCN (3.57 g, 39.9 mmol), and KI (4.42 g, 26.6 mmol) in dry DMF (30 mL) was refluxed under argon for 4.5 h. After cooling to room temperature, the mixture was extracted with CH2Cl2 (100 mL) and H2O (100 mL) three times. Compound 7 (2.47 g, 56.6%) was obtained as a white solid after purified through silica gel column with CH2Cl2/PE (1:2, v:v). 1H NMR (400 MHz, CDCl3) δ 8.12 (s, 2H), 4.36 (t, J ¼ 8.0 Hz, 4H), 1.75 (m, 4H), 1.42 (dt, 4H), 0.97 (t, J ¼ 8.0 Hz, 6H) ppm. Synthesis of 8. [15] A mixture of 7 (4.10 g, 12.50 mmol) and DBU (1.87 mL, 12.50 mmol) in dry n-butanol (40 mL) was refluxed under argon for 5 h. After cooling to room temperature, the mixture was poured into methanol (300 mL) and filtered. Then the mixture was pu­ rified through silica gel column using CH2Cl2 as eluent to give 8 (1.22 g, 29.7%) as a green solid. Mp: > 305 � C; 1H NMR (400 MHz, CDCl3) δ 9.46 (s, 8H), 4.68 (t, J ¼ 8.0 Hz, 16H), 2.06 (m, 16H), 1.73 (m, 16H), 1.16 (t, J ¼ 8.0 Hz, 24H) ppm; 13C NMR (100 MHz, CDCl3) δ 167.3, 136.9, 134.4, 124.1, 66.3, 30.8, 19.3, 13.9 ppm; HRMS (MALDI-TOF): Calcd for C72H82N8O16 1314.5849, Found 1314.5835 (M ).

Fig. 2. (a) J V curves of solar cells based on PFBZ:CuPcTI-C11, (b) current density–voltage and SCLC fitting curves of only electron devices. 4

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Compound H2PcTI-Ph and H2PcTI-C11 were synthesized in the same procedure as 8. Synthesis of H2PcTI-Ph. Compound 4 (1.02 g, 5.20 mmol) and DBU (0.76 mL, 5.20 mmol) in dry n-hexanol (20 mL) led to compound H2PcTI-Ph (313 mg, 30.5%) as a green solid. Mp: > 305 � C; 1 H NMR (400 MHz, CDCl3) δ 10.20 (s, 8H), 7.59 (t, J ¼ 8.0 Hz, 4H), 7.44 (d, J ¼ 8.0 Hz, 8H), 3.01 (m, 9H), 1.34 (d, J ¼ 8.0 Hz, 48H) ppm; 13C NMR (100 MHz, CDCl3) δ 167.5, 147.1, 141.1, 133.8, 130.5, 126.8, 124.2, 120.1, 31.5, 30.1, 29.6, 24.1 ppm; HRMS (MALDI-TOF): Calcd for C88H78N12O8 1430.6066, Found 1430.6024 (M ). Synthesis of H2PcTI-C11. Compound 4 (200 mg, 0.57 mmol) and DBU (0.08 mL, 0.57 mmol) in dry n-hexanol (4 mL) led to compound H2PcTI-C11 (63 mg, 31.4%) as a green solid. Mp: > 305 � C; 1H NMR (400 MHz, CDCl3) δ 9.52 (s, 8H), 4.56 (m, 4H), 2.42 (m, 8H), 2.07 (m, 8H), 1.56 (s, 48H), 0.96 (t, J ¼ 8.0 Hz, 24H) ppm; 13C NMR (100 MHz, CDCl3) δ 167.6, 139.6, 134.1, 118.1, 53.4, 32.6, 31.7, 26.7, 22.7, 14.1 ppm; HRMS (MALDI-TOF): Calcd for C84H102N12O8 1406.7944, Found 1406.7918 (M ). Synthesis of 9. [15] Compound 8 (100 mg, 0.07 mmol) and Zn (CH3COO)2 (21.2 mg, 0.14 mmol), was refluxed in dry DMF (4 mL) under argon for 5 h. After cooling to room temperature, the mixture was poured into the methanol (20 mL) and filtered. Then the mixture was purified through silica gel column using CH2Cl2/CH3OH (100:1, v:v) as eluent to give 9 (101 mg, 96.7%) as a blue solid. Mp: > 305 � C. 1H NMR (400 MHz, CDCl3) δ 9.40 (s, 8H), 4.28 (s, 16H), 1.77 (s, 16H), 1.51 (s, 16H), 1.03 (t, J ¼ 8.0 Hz, 24H) ppm; 13C NMR (100 MHz, CDCl3) δ 167.8, 153.3, 139.1, 132.4, 123.4, 66.1, 30.5, 19.1, 13.7 ppm; HRMS (MALDI-TOF): Calcd for C72H80N8O16Zn 1376.4984, Found 1376.4905 (M ). Compound ZnPcTI-Ph, CuPcTI-Ph, CuPcTI-C11 were synthesized in the same procedure as 9. Synthesis of ZnPcTI-Ph. Compound H2PcTI-Ph (100 mg, 0.07 mmol) and Zn(CH3COO)2 (21.16 mg, 0.14 mmol) in dry DMF (4 mL) led to compound ZnPcTI-Ph (101 mg, 96.72%) as a green solid. Mp: > 305 � C; UV–vis (THF): λmax (ε) ¼ 694 nm (353000 M 1 cm 1); 1H NMR (400 MHz, CDCl3) δ 9.97 (s, 8H), 7.57 (t, J ¼ 8.0 Hz, 4H), 7.44 (d, J ¼ 8.0 Hz, 8H), 3.01 (s, 8H), 1.29 (s, 48H) ppm; 13 C NMR (100 MHz, CDCl3) δ 167.8, 154.7, 147.2, 142.9, 132.8, 130.4, 126.9, 124.1, 119.2, 29.6, 24.1 ppm; HRMS (MALDI-TOF): Calcd for C88H76N12O8Zn 1492.5201, Found 1492.5278 (M ). Synthesis of CuPcTI-Ph. Compound H2PcTI-Ph (125 mg, 0.087 mmol) and Cu(CH3COO)2 (26.13 mg, 0.17 mmol) in dry DMF (5 mL) led to compound CuPcTI-Ph (128 mg, 98.2%) as a blue solid. Mp: > 305 � C; UV–vis (THF): λmax (ε) ¼ 690 nm (299000 M 1 cm 1); 1H NMR (400 MHz, CDCl3) 1H NMR (400 MHz, CDCl3) δ 7.56 (t, 4H), 7.38 (m, 8H), 2.90 (s, 8H), 1.27 (t, 48H) ppm; HRMS (MALDI-TOF): Calcd for C88H76N12O8Cu 1491.5205, Found 1491.5167 (M ). Synthesis of CuPcTI-C11. Compound H2PcTI-C11 (200 mg, 0.15 mmol) and Cu(CH3COO)2 (42.52 mg, 0.28 mmol) in dry DMF (8 mL) led to compound CuPcTI-C11 (205 mg, 98.2%) as a blue solid. Mp: > 305 � C; UV–vis (THF): λmax (ε) ¼ 688 nm (325000 M 1 cm 1); 1H NMR (400 MHz, CDCl3) δ 3.76 (s, 4H), 2.41 (s, 8H), 2.12 (s, 8H), 1.54 (s, 48H), 1.02 (s, 24H) ppm; HRMS (MALDI-TOF): Calcd for C84H100N12O8Cu 1467.7083, Found 1467.7016 (M ). Synthesis of 10. [14] A mixture of 9 (500 mg, 0.38 mmol) and KOH (1.02 g, 18.1 mmol) in n-butanol/THF (55 mL, 10:1, v:v) was stirred at 60 � C for 24 h. After cooling to room temperature, water (30 mL) was then added and the reaction was stirred for another 5 min. The phases were separated, and the water phase was slowly acidified with HCl (12 M) to get blue precipitate. A blue solid 10 (305 mg, 90.1%) was obtained after filtered. 1H NMR (400 MHz, KOH/H2O) δ 9.61 (s, 8H) ppm; HRMS (MALDI-TOF): Calcd for C40H16N8O16Zn 927.9976, Found 927.9932 (M ). Compound 11 were synthesized in the same procedure as 10. Synthesis of 11. Compound 8 (500 mg, 0.38 mmol) and KOH (3.20 g, 57.0 mmol), in n-butanol/THF (55 mL, 10:1, v:v) was stirred at 90 � C for 48 h led to compound 11 (135 mg, 41.2%). 1H NMR (400 MHz, KOH/ H2O) δ 9.59 (s, 8H) ppm; HRMS (MALDI-TOF): Calcd for C40H18N8O16

866.0841, Found 866.0880 (M ). Synthesis of ZnPcTA. [14b] A mixture of 10 (100 mg, 0.11 mmol) in acetic anhydride (4 mL) was refluxed under argon for 10 h. After cooling to room temperature, the blue solid ZnPcTA (90 mg, 97.5%) was ob­ tained after filtered. HRMS (MALDI-TOF): Calcd for C40H8N8O12 855.9553, Found 855.9514 (M ). Compound H2PcTA were synthesized in the same procedure as ZnPcTA. Synthesis of H2PcTA. Compound 11 (100 mg, 0.11 mmol) in acetic anhydride (4 mL) to led compound H2PcTA (90 mg, 97.5%) as green solid. HRMS (MALDI-TOF): Calcd for C40H10N8O12 794.0418, Found 794.0469 (M ). Synthesis of H2PcTI-Ph. [13] A mixture of H2PcTA (50 mg, 0.063 mmol) and 2,6-diisopropylaniline (0.21 g, 1.17 mmol) in NMP (5 mL) was stirred at 180 � C under argon for 10 h. After cooling to room temperature, the mixture was poured into the methanol (20 mL) and filtered. Then the mixture was purified through silica gel column using CH2Cl2/PE (1:1, v:v) as eluent to give compound H2PcTI-Ph (19.3 mg, 38.4%) as a blue solid. Mp: > 305 � C; 1H NMR (400 MHz, CDCl3) δ 10.20 (s, 8H), 7.59 (t, J ¼ 8.0 Hz, 4H), 7.44 (d, J ¼ 8.0 Hz, 8H), 3.01 (m, 9H), 1.34 (d, J ¼ 8.0 Hz, 48H) ppm; 13C NMR (100 MHz, CDCl3) δ 167.5, 147.1, 141.1, 133.8, 130.5, 126.8, 124.2, 120.1, 31.5, 30.1, 29.6, 24.1 ppm; HRMS (MALDI-TOF): Calcd for C88H78N12O8 1430.6066, Found 1430.6024 (M ). Compound ZnPcTI-Ph were synthesized in the same procedure as H2PcTI-Ph. Synthesis of ZnPcTI-Ph. Compound ZnPcTA (50 mg, 0.063 mmol) and 2,6-diisopropylaniline (0.21 g, 1.17 mmol) in NMP (5 mL) led to compound ZnPcTI-Ph (22 mg, 44.4%) as a blue solid. Mp: > 305 � C; UV–vis (THF): λmax (ε) ¼ 694 nm (353000 M 1 cm-1); 1H NMR (400 MHz, CDCl3) δ 9.97 (s, 8H), 7.57 (t, J ¼ 8.0 Hz, 4H), 7.44 (d, J ¼ 8.0 Hz, 8H), 3.01 (s, 8H), 1.29 (s, 48H) ppm; 13C NMR (100 MHz, CDCl3) δ 167.8, 154.7, 147.2, 142.9, 132.8, 130.4, 126.9, 124.1, 119.2, 29.6, 24.1 ppm; HRMS (MALDI-TOF): Calcd for C88H76N12O8Zn 1492.5201, Found 1492.5278 (M ). Declaration of competing interest The authors declare no competing financial interest. Acknowledgment The work was supported by grants National Natural Science Foun­ dation of China (No. 21562031, 51863012, 51833004), Natural Science Foundation of Jiangxi Province in China (No. 20171ACB21012 and 2018ACB21022). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi. org/10.1016/j.dyepig.2019.107980. References [1] Sakai K, Hiramoto M. Efficient organicp-i-n solar cells having very thick codeposited i-layer consisting of highly purified organic semiconductors. Mol Cryst Liq Cryst 2008;491(1):284–9. [2] (a) Melville OA, Grant TM, Lessard BH. Silicon phthalocyanines as N-type semiconductors in organic thin film transistors. J Mater Chem C 2018;6(20): 5482–8.(b) Nar I, Atsay A, Altindal A, Hamuryudan E, o-Carborane. Ferrocene, and phthalocyanine triad for high-mobility organic field-effect transistors. Inorg Chem 2018;57(4):2199–208. [3] O’Flaherty SM, Hold SV, Cook MJ, Torres T, Chen Y, Hanack M, Blau WJ. Molecular engineering of peripherally and axially modified phthalocyanines for optical limiting and nonlinear optics. Adv Mater 2003;15(1):19–32. [4] Ghani F, Kristen J, Riegler H. Solubility properties of unsubstituted metal phthalocyanines in different types of solvents. J Chem Eng Data 2012;57(2): 439–49. [5] (a) Liang F, Shi F, Fu Y, Wang L, Zhang X, Xie Z, Su Z. Donor–acceptor conjugatesfunctionalized zinc phthalocyanine: towards broad absorption and application in organic solar cells. Sol Energy Mater Sol Cells 2010;94(10):1803–8.(b) Walker B,

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