Z Isomers Based on Tetraphenylethene

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Configuration-Controllable E/Z Isomers Based on Tetraphenylethene: Synthesis, Characterization, and Applications Wanli Tian, Ting Ting Lin, Hua Chen, and Weizhi Wang ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b19672 • Publication Date (Web): 21 Jan 2019 Downloaded from http://pubs.acs.org on January 26, 2019

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ACS Applied Materials & Interfaces

Configuration-Controllable E/Z Isomers Based on Tetraphenylethene: Synthesis, Characterization, and Applications Wanli Tian,† Tingting Lin,‡ Hua Chen,† and Weizhi Wang*,† †State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University, Shanghai 200434, P. R. China ‡Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore KEYWORDS. E/Z isomers, configuration-controllable, tetraphenylethene, Scholl reaction, transistors ABSTRACT: Configuration-controllable E/Z isomers based on tetraphenylethene were prepared with a facile and effective method. Firstly, compound 1 and 2, configuration-controllable precursors of E/Z isomers, were synthesized. Then pure E/Z isomers were obtained via Suzuki reaction, avoiding the difficulties of separation. The conformational changes of E/Z isomers can occur through photo-activation. Importantly, red-shifts of 66nm from 6 (E-) to 3 (Z-) and 58nm from 7 (E-) to 4 (Z-) were observed remarkably on the PL emission spectra. Z-isomer showed longer fluorescence lifetime compared with E-isomer. Z-isomers 3 and 4 exhibited piezofluorochromism under grinding while E-isomers 6 and 7 showed no such behaviors. E-isomer has better thermal stability than Z-isomer. Lastly, graphene-like molecules were synthesized with the FeCl3/CH3NO2 system. E- and Z-isomers after oxidation showed negligible differences on the PL emission spectra, because the effective conjugated lengths of oxidized E- and Z-isomers were both extended. Furthermore, the fabricated field-effect transistors showed nice performance with mobilities 0.92 and 1.14 cm-2V-1s-1 at low operating voltages, respectively.

INTRODUCTION E/Z isomerization is a hot research topic in bio-medical1-2 and chemical3-12 fields nowadays. Although possessing identical chemical formula, cis-trans isomers can perform distinguishing properties because of varying geometrical positions in space.13-15 For example, Tang’s group synthesized a tailored cyanostilbenebased molecule with reversible E/Z isomerization which could show multiple yet controllable photoresponsive behaviors under diverse conditions.16 Zheng et al. first reported that the pure (2R, 4S)-difenoconazole has better bioactivity and lower ecotoxicity compared with its stereoisomers, showing excellent environmental behaviors in vegetables and soil.17 Wu’s group found that cisdichlorodiamineplatinum( Ⅱ ) is an efficient drug to cancer cells while its trans form doesn’t work at all.18-19 Lieker et al. synthesized an azo compound with photosensitivity via E/Z isomerization and it can thus be regarded as a multifunctional organic field-effect transistor.20 Considering these attractive properties as well as miscellaneous applications in life and material science, obtaining a pure isomer is very important and intriguing even though it is so tough to synthesize and separate a pure Eisomer and Z-isomer. Tetraphenylethene and its derivatives (TPEs) have attracted much attention due to the unique phenomenon of aggregationinduced emission (AIE) effect, which was first discovered by

Tang’s group in 2001.21 After that, TPEs have demonstrated a great deal of applications in optoelectronic devices,22-25 bioimaging,26 biosensors27-28 and fluorescent chemosensors29 because of their charming properties in solid and aggregated state. Recently, E/Z isomers of TPEs with distinct properties have aroused a lot of interest. For example, pure isomers displayed tremendous mechanochromic behaviors and have totally different biological responses to targeted enzymes and nucleic acid.30-33 E/Z isomers demonstrated distinct mechanochromic properties and the AIE dots of the Z-isomer have stronger brightness as well as intensive cell labeling brightness as compared to the E-isomer.34 However, the column separation after chemical synthesis is the main and timeconsuming method to obtain E/Z isomers of TPEs with low yields. In other words, it is very difficult and challenging to separate E/Z isomers based on TPEs even by high performance liquid chromatograph according to previous report.35 Considering the above issue, herein, it is of great importance and urgency to seek a facile method of obtaining E/Z isomers based on TPEs by a onestep route, which is exactly what we are doing in this work. Then their unique properties and attractive applications can be further investigated in detail. In this work, firstly, we synthesized compound 1 and 2, configuration-controllable precursors of cis-trans isomers, then we obtained pure and configuration-controllable cis-trans isomers via the facile Suzuki reaction. This synthetic route provided a brand

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new idea of synthesizing E/Z isomers based on TPEs, avoiding difficulties of separating isomers reported previously. Through further investigation, it was found that Z-isomer showed red-shift performance compared with E-isomer on the PL emission spectra and exhibited longer fluorescence lifetime than E-isomer. Zisomers demonstrated piezofluorochromism under grinding while E-isomers didn’t show such behaviors. However, E-isomer has better thermal stability compared with Z-isomer. Then a series of near-planar polycyclic aromatic hydrocarbons (PAHs) were prepared with the FeCl3/CH3NO2 system. The oxidized products of E- and Z-isomers showed a negligible difference on the PL emission spectra. It was because the effective conjugated lengths of E- and Z-isomers after oxidation were both extended, thus exhibiting similar PL performances. Interestingly, emissiontunable multicolor graphene-like molecules were obtained by controlling the oxidation time, implying that the oxidative reaction is a step-wise and steerable process. That is to say, well-defined and multicolor-tunable graphene-like molecules can be prepared with a facile and efficient method. EXPERIMENTAL SECTION Materials. Most chemicals and reagents used were purchased from Aldrich or Sinopharm Chemical Reagent Company unless otherwise specified. N, N-dimethylformamide (DMF) was of high pressure liquid chromatography grade without any purification and all other solvents were of analytical grade as well as purified with standard methods. Instruments. 1H and 13C nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AVANCE III HD 400 MHz spectrometer using deuterated dichloromethane (CD2Cl2) or chloroform as the solvent and tertramethylsilane as an internal standard ( = 0.00 pm). The molecular weights were measured by AB SCIEX matrix assisted laser desorption ionization time-offlight (MALDI-TOF) mass spectrometry (AB SCIEX, Framingham, MA, USA) and PE680-ST8 Gas ChromatographyMass Spectrometer (GC-MS) . UV-vis absorption spectra (UV) were measured on a PerkinElmer Lambda 750 UV-vis spectrophotometer at room temperature. Fluorescence spectra (PL) were measured with an Edinburgh FLS920 spectrometer. PL lifetimes were obtained on a Photo Technology International, Inc. QM40 with a time-corrected single photon counting system at room temperature. PL quantum yields measurements were performed on an integrating sphere with Photo Technology International, Inc. QM40. Thermogravimetric analysis (TGA) was determined using a Mettler Toledo TGA1 instrument at a heating rate of 10 °C /min under N2 atmosphere. The differential scanning calorimetry (DSC) analysis was evaluated using a Q2000 DSC (TA Instrument LLC) instrument at a scan rate of 10 °C /min. Powder X-ray diffraction patterns were obtained using a Bruker D2 X-ray diffractometer with Cu K radiation. Fourier-transform infrared (FT-IR) spectra were performed with a Nicolet 6700 (Thermofisher) spectrometer. Raman spectra were obtained using an XploRA (HORIBA JobinYvou) spectrometer. Cyclic voltammetry (CV) was conducted on an electrochemical workstation (CHI 600E).The electrolytic cell consists of three electrodes: working electrode (glassy carbon electrode, 0.08cm2), counter electrode (platinum wire) and reference electrode (Ag/Ag+ electrode). The thin films of oligomers were coated on a glassy carbon electrode. The test was conducted in an electrolyte of 0.1M tetrabutylammonium hexafluorophosphate in acetonitrile using ferrocene as an internal standard with a scan rate of 100mV/s under the constant protection of N2. X-ray single crystallographic data were obtained on a P4 Bruker diffractometer furnished with a rotating anode using graphite-monochromated Mo K radiation

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with  = 0.71073 Å and a Bruker SMART 1K CCD area detector which employs the SMART program. The data were processed by the SAINT program. The SADABS program was used for an empirical absorption correction based on spare reflections, scaling of diffraction data and the decay correction. The structure of single crystal was solved with a direct procedure in the Bruker SHELXL36 and corrected with F2 matrix least squares. Several anisotropic thermal parameters were used to refine all non-hydrogen atoms which were added at calculated positions as fixed contributors. The two-dimensional gazing-incidence X-ray diffraction (2D GIXRD) data were obtained at BL14B1, Shanghai Synchrotron Radiation Facility. The grazing-incidence angle is 0.25° and the  = 0.124 nm. Atomic force microscopy (AFM) was conducted on a Digital Instruments NanoScope IV with the tapping mode. (Bruker Multimode 8, America) Organic Field-effect Transistor (OFET) Fabrication. A commercially available SiO2 (300 nm) /Si wafer (p-type) was sequentially washed with acetone, methanol, H2O/H2SO4 and ionized water. The graphene molecule in dichloromethane (CH2Cl2) solution (0.15 wt %) was spin-coated on a clean SiO2/Si wafer with a gluing machine at a speed of 6000 r/min. Then a 100 nm thick film to be semiconductor was placed in a vacuum oven to evaporate the surplus solvent. Two 50nm thick gold electrodes were deposited on the surface of the semiconductor layer serving as source and drain electrodes respectively through a shadow mask. The ionic gel was used as the dielectric layer. The formula of ionic gel composes of a triblock copolymer, poly (styrene-block-methyl methacrylate-block-styrene) (PS-PMMA-PS) (MW = 21.1 kg/mol, MPS = 4.3 kg/mol, MPMMA = 12.5 kg/mol), and an ionic liquid (1ethyl-3-methyllimidazolium bis(trifluoromethylsulfonyl)imide) in ethyl acetate solution. The weight ratio of copolymer, ionic liquid and solvent was 0.7:10:20. These prepared ionic solutions were drop-cast to cover the surfaces of source and drain electrodes as well as semiconductor films. The OFET electrical characteristics were performed with a Keithley 4200-SCS/F at room temperature. Minimal current between S and D electrodes is measured when no voltage is applied to the gate, the device is “off” state. When a negative gate voltage is biased, electrons or holes will be induced at the organic and dielectric layers interface and the current generates, the device is “on” state. Scheme 1. Synthetic Routes towards Compounds 3-7and 3c7ca.

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aReagents and conditions: i. Pt(PPh ) , DMF, 90 °C, 24h; ii. room 3 4 temperature, 0.5h; iii. Pd(PPh3)4, toluene, 2mol/L K2CO3/H2O, 87 °C, 48h; iv. Pd(PPh3)4, DMF, K3PO4, 90 °C, 48h and v. FeCl3, CH3NO2, CH2Cl2, room temperature.

RESULTS AND DISCUSSION Synthesis. The synthetic routes are clearly depicted in Scheme 1. Configuration-controllable isomers, for example, compound 3 (Z-) and compound 6 (E-), were obtained via Suzuki cross-coupling reaction. First, configuration-controllable precursors, compound 1 and 2, were obtained. Then, compound 3 (Z-) was synthesized successfully by the cross-coupling of compound 1 and 1-Bromo-4phenylbenzene. Similarly, compound 6 (E-) was obtained via the cross-coupling reaction of compound 2 and 4-biphenylboronic acid. There was a difference between the reactions of obtaining compound 3 (Z-) and 6 (E-). The solvent and base were separately replaced with DMF and K3PO4 instead of toluene and K2CO3 when synthesizing compound 6 (E-). The reasons are that 4biphenylboronic acid has better solubility in DMF compared with its poor solubility in toluene and the weaker alkalinity of K3PO4 improves the cross-coupling of compound 2 and 4-biphenylboronic acid as compared to K2CO3. However, the isomer of compound 5 cannot be obtained as expected with trying to change the solvent, base, catalyst, temperature and time of the reaction for a long time. The reason may be that the structure of 9-Phenanthreneboronic acid is too big, making it difficult to react with compound 2. In our work, the pure single crystal of compound 5 was obtained from its CH2Cl2/petroleum ether and identified through X-ray

Figure 1. The ORTEP drawing of 5. crystallographic analysis (Figure 1 and Table S3), which further confirmed the accurate Z-configurations of compounds 3, 4 and 5. 1H and 13C NMR spectroscopy provided reasonable evidences that compounds 6 and 3 as well as compounds 7 and 4 are E/Z isomers (details in Supporting Information).

Figure 2. NOESY-NMR of (a) 6 (trans-) and (b) 3 (cis-) (enlarged). Characterization. The geometric structures of E/Z isomers can be further testified via COSY and NOESY NMR spectroscopy (Figure 2). For the E-isomer, compound 6, the multiple shift at  = 7.57 ppm should correspond to the resonances of H 19-22 protons due to the electron-withdrawing property of the neighboring phenyl group. The integral of the multiple at  = 7.40 ppm suggests a relative proton number of 8, corresponding to the H 11-18 protons due to their strong correlation with H 19-22. The resonances at  = 7.31 and 7.28 ppm are H 27 and H 28 because of their correlation with H 11-18. The integral of the multiple at  = 7.13 ppm suggests a relative proton number of 14, corresponding to the H 1-10 and H 23-26. As shown in Figure 2a, the cross-peaks in the blue dot circles manifest clear correlations between H 1-10, 23-26 and H 11-18, which implies that ring A and D are close in space, in other words, compound 6 is an E-isomer. Meanwhile, clear correlations between H 1-10 and H 11-18 cannot be found in Figure 2b because ring A/D are far from ring B/C in space, indicating the Zconfiguration of compound 3. It can also be proved by their COSY spectroscopy (Figure S36-37). The COSY and NOESY NMR spectroscopy of compounds 7 and 4 confirmed their geometrical structures are E/Z-configurations, respectively. (Figure S40-43) IR spectroscopy and Raman spectroscopy also indicated the compounds 6 and 3 as well as compounds 7 and 4 are indeed E/Z isomers (Figure S44-45). The retention time of GC-MS of 6 and 3 was 32.62 and 32.45 min (Figure S38), respectively, further implying the accurate E/Z-configurations of 6 and 3. Similarly, the E/Z- configurations of 7 and 4 were also confirmed by comparing the retention time of GC-MS of 7 (18.84 min) and 4 (18.90 min) (Figure S39).



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oxidative intermediates of compound 5 (Figure 4). Two new C-C bonds of 5 formed in a large proportion after 15 min of oxidation time. However, it took much longer time to form the remaining three C-C bonds. Graphene-like molecule 5c was obtained after being oxidized for 100 min, which supported the mechanism of stepwise ring-closing and also indicated that it took different oxidation time for adjacent phenyl rings of different positions to form new C-C bonds.

Figure 3. (a) Photographs of compounds 3-7 with different oxidation time under 365nm UV light. (b) The trajectory to tune colors via controlling the oxidation time of 5 displayed in the CIE coordinate diagram (ex=365nm).

Figure 4. MALDI-TOF MS spectra of compound 5 with varying oxidation time. 5 (30mg) in CH2Cl2 (30ml) solution was oxidized with the saturated FeCl3/CH3NO2 system (1ml) according to Supporting Information. Methanol was used to quench each mixture obtained from the reaction bottle before testing. In our work, we obtained a variety of graphene molecules 3c-7c by a mild intermolecular cyclodehydrogenation aiming to explore the connection between the structure and property. The FeCl3/CH3NO2 oxidation system has been a versatile and powerful method to synthesize PAHs for its many advantages.37 Herein, elaborate near-planar molecules were synthesized with quantitative yields with the FeCl3/CH3NO2 oxidation system. Interestingly, it can be seen by naked eyes that ring-closed structures emitted varying colors with varying oxidation time (Figure 3). For example, the fluorescence emission of compound 5 changed from blue to brick-red with increased oxidation time, indicating that emission-tunable colorful graphene-like molecules can be obtained with controllable oxidation time. In other words, intermolecular oxidative cyclodehydrogenation is a stepwise process, which can be confirmed by analyzing MALDI-TOF mass spectra of the

Figure 5. Normalized UV absorption (a) and PL spectra (b) of compounds 3-5 & 3c-5c in CH2Cl2 solutions. Normalized UV absorption (c) and PL spectra (d) of compounds 6-7 & 6c-7c in CH2Cl2 solutions. Optical Properties. UV-vis absorption and PL emission spectra of oligomers in their CH2Cl2 solutions were measured in order to investigate the differences of E/Z isomers and the changes after intermolecular cyclodehydrogenation in optical properties. The UV spectra of compounds 3 (Z-) and 6 (E-) in DCM solutions were nearly identical with an absorption peak at 327 nm. Similarly, 4 (Z) and 7 (E-) showed an identical absorption peak (331nm). (Figure 5a and 5c). There was a distinct difference in PL emission spectra of Z-isomer and E-isomer (Figure 5b and 5d). The corresponding values of the PL spectra of compounds 6 (E-) and 3 (Z-) were at 440 and 506 nm, respectively, showing a red-shift of 66 nm from 6 (E-) to 3 (Z-). Similarly, the maximal values of 7 (E-) and 4 (Z-) were at 436 and 494 nm, which also implied a red-shift of 58 nm from 7 (E-) to 4 (Z-) on the PL spectra. The explanation for the above discovery may be that the Z-isomer has a less twisted conformation compared with the E-isomer. Therefore, its internal rotations of the phenyl rings and partial twisting of the C=C bond are blocked partly, resulting in a reduction of nonradiative deactivation process, finally showing a red-shift performance on the PL emission spectra. 37-39 As expected, there was a difference in the lifetime of Z-isomer and E-isomer. The lifetimes of 3 (Z-) and 6 (E-) were 0.9941 and 0.8440 ns, as well, the lifetimes of 4 (Z-) and 7 (E-) were 0.8506 and 0.7511 ns, respectively (Figure S58). Compounds 3-5 have good solubility in many common solvents such as tetrahydrofuran (THF), CH2Cl2, chloroform, ethyl acetate, acetone and so on. However, they show poor solubility in H2O and methanol because of their hydrophobic aromatic groups. As we all know, TPE is well-known for its unique AIE effect. Herein, the AIE properties of compounds 3-5 were explored under UV irradiation. Compounds 3-5 all emitted no light in their dilute THF solutions on account of fast molecular internal rotations of phenyl rings deactivating the excited state through nonradioactive decay channels. In their THF/H2O mixtures, oligomers 3-5 showed enhanced emission intensity with an increasing content of water (Figure 6a). It was observed that 3 (Z-) exhibited a red-shift emission as compared to 6 (E-) when the content of water was


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added to 80% and 90%, which can be confirmed on their PL spectra (Figure 6b and 6d). The intensities of emission spectra didn’t show obvious changes until the water fractions up to 70% for oligomers 3 (Z-), 4 (Z-), 6 (E-) and 7 (E-) (Figure 6b-d). A red-shift of the emission peak of 5 was observed with the water added (Figure S49). Different from its isomer, compound 3 (Z-), the emission intensity of 6 (E-) became weaker at 90% water fraction compared with 80%. The reason was that abundant water will make the formation and precipitation of large-sized aggregates, resulting in a decrease of the effective concentration of solution.40 What’s more, compared with 3 (Z-), compound 6 (E-) has a more twisted conformation to trap solvent molecules inside, making the amorphous aggregates become loose. Therefore, the internal rotation of free phenyl rings weakened the emission intensity23 with a particularly high water fraction. Intriguingly, the emission region was dramatically broadened through locking phenyl rings with the FeCl3/CH3NO2 system. Herein, a series of new color of graphene-like molecules appeared by steering numbers of locked phenyl rings. In our work, twisted oligomers 3-7 were transformed into near-planar compounds 3c-7c with the FeCl3 catalyst, which can also be seen from IR spectra (Figure S46). Luminogens 3c-7c displayed their absorption peaks at 365, 382, 387, 363 and 384 nm, respectively, which all exhibited a red shift compared with their precursors. For example, the absorption maximum wavelengths of oligomers 3 (Z-), 6 (E-), 3c and 6c were 327, 326, 365 and 363 nm, respectively. In addition, their emission peaks showed a similar red shift with the extended conjugated length. The maximal values of the PL spectra of 3c and 6c were at 531 and 525 nm, respectively, both showing a red shift as compared to their precursors 3 (Z-) (506 nm) and 6 (E-) (440 nm). Similarly, 4c and 7c exhibited maximal emission values at 537 and 533 nm, also showing a red shift as compared to 4 (Z-) (494 nm) and 7 (E-) (436nm), respectively. It can be found that the oxidized products of E- and Z- isomers showed a negligible difference on the PL spectra, which was obviously different from the contrast between E-isomer and Z-isomer. The reason for all those bathochromic-shifted phenomena was that the extended conjugated length will cause the increase of the degree of πelectrons delocalization and the narrowing of the molecular electronic energy level, showing a red shift on the PL spectra. From the perspective of electronic energy level, oxidized near-planar molecules jumped to a lower excited state from the ground state upon excitation compared with twisted precursors, so red shifts of UV and PL spectra were observed.

Figure 6. (a) Fluorescence images of compounds 3-7 in THF/H2O mixtures with different contents of water under 365 nm UV light. PL spectra of 3 (b), 4 (c), 6 (d) and 7 (e) in THF/H2O mixtures with different contents of water.

Figure 7. 1H NMR spectra of (a) 7 (E-), (c) 4 (Z-) exposed to UV lamp (365 nm) for 15 min in CD2Cl2, (b) 7 (E-) and (d) 4 (Z-). Photoinduced Conformation Changes. Photoisomerization has attracted much attention and its kinds of applications in optoelectronic devices, such as molecular switches, electronics and motors,8,10 have been investigated. In this work, we explored the photoinduced conformation changes of isomers, 3 (Z-) and 6 (E-), 4 (Z-) and 7 (E-) through NMR spectroscopy in order to better understand the E/Z isomerization process. As shown in Figure 7, the dichloromethane-d solution of Z-isomer, 4 was irradiated by a



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UV lamp for 15 min, then new resonance peaks appeared compared with the original spectrum and they are in accordance with the resonance peaks of E-isomer, 7. This suggested that compound 4 (Z-) has potentials to be converted into its isomer under the irradiation of a UV Lamp for some time. However, when compound 7 (E-) was treated with the same condition, there was no obvious spectral change detected, implying that the possibility of E to Z isomerization is particularly low because of the higher energy barrier of isomerization from E-isomer to Z-isomer. Similarly, the obvious spectral change of compound 3 (Z-) in the dichloromethane-d solution was observed after being irradiated by a UV lamp for 15 min, which is consistent with the spectrum of compound 6 (E-). While, its isomer, compound 6 showed little tendency to undergo the E/Z isomerization process because it will cost more energy to be converted into a Z-isomer (Figure S50). Therefore, it is concluded that Z-isomers, 3 and 4 have potentials to be utilized in stimuli-responsive actuators and sensors due to their abilities to be converted into E-isomers.

Figure 9. B3LYP/6-31G (d, p) calculated molecular orbital amplitude plots of the HOMOs and the LUMOs of 3, 3c, 4, 4c.

Figure 8. TGA curves of 3 (Z-) and 6 (E-), 4 (Z-) and 7 (E-). Thermal Properties. The thermal durability of -conjugated oligomers is seen as one of the most crucial parameters when applied in organic optoelectronic fields. Herein, the thermogravimetric analyses of oligomers 3 (Z-), 6 (E-), 4 (Z-) 7 (E), 3c and 4c were measured under N2 atmosphere on purpose of testing the thermal stability. As exhibited in Figure 8, E-isomer and Z-isomer have different thermal decomposition temperatures. The decomposition temperatures of oligomers 6 (E-) and 3 (Z-) were 363 and 346 °C, respectively. The decomposition temperatures of 7 (E-) and 4 (Z-) were 326 and 319 °C, respectively. It can be found that the as-synthesized E-isomer has better thermal stability than Zisomer. The reason may be that the E-isomer has a more twisted conformation as compared to the Z-isomer. The thermal decomposition temperatures of graphene-like molecules 3c and 4c were 404 and 377 °C (Figure S47-48), showing better thermal stability than their precursors because of the extended conjugated length and the increased structural planarity. Thus, the performances of optoelectronic devices based on graphene-like molecules are largely promoted due to their excellent thermal stability.

Theoretical Calculations. Theoretical calculations of oligomers were conducted using density functional theory (DFT) method with Gaussian 09 software package at the level of theory B3LYP/6-31G (d, p)41 on purpose of better understanding the relationship between electronic structures and electrochemical properties. The optimized geometric structures, the electronic configurations of the highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) of oligomers 3-7 and 3c-7c are displayed in Figure 9 and Figure S53-55. The geometry structures of precursors 3-7 are similar with propeller-shaped structures. The biphenyl unit, naphthyl unit, phenanthryl unit and phenyl unit are twisted from the plane of ethenyl unit, indicating all of them possess a propeller-shaped conformation. On the basis of that, the main cause of AIE effect can be concluded that the excited state is deactivated by fast internal rotations of these substituent units and partial twisting of the C=C bonds through nonradiative decay channels. Thus, the intermolecular rotation and - stacking are obstructed because of this kind of conformation, hindering the emission quenching. It is found that the electron cloud distributions of HOMOs and LUMOs of these precursors 3-7 are mainly located on the central ethenyl unit. Whereas, for the oxidized graphene molecules 3c-7c, their electron clouds of HOMOs and LUMOs become more evenly distributed compared with precursors 3-7. This suggests the extended degree of -electron delocalization, which is consistent with their more effective conjugated lengths and near-planar conformations owing to the formation of new C-C bonds. Table 1. Electrochemical properties of compounds 3-7 and 3c7ca


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ACS Applied Materials & Interfaces compound

Eonset-ox (V)

HOMO (eV)

crosspoint

Eg

LUMO

(eV)

(eV)

(nm)

3

0.91

-5.66

391

3.17

-2.49

3c

0.81

-5.56

464

2.67

-2.89

4

0.88

-5.63

387

3.20

-2.43

4c

0.79

-5.54

469

2.64

-2.90

5

0.94

-5.69

381

3.25

-2.44

5c

0.77

-5.52

478

2.59

-2.93

6

0.92

-5.67

376

3.30

-2.37

6c

0.82

-5.57

461

2.69

-2.88

7

0.90

-5.65

375

3.31

-2.34

7c

0.80

-5.55

466

2.66

-2.89

aAbbreviations:

Eonset-ox is the onset potential for oxidation calculated from cyclic voltammetry. cross-point is the intersection of the UV spectra and the PL spectra. HOMO = -e (Eonset-ox 0.0468V)-4.8eV (1) LUMO = Eg + HOMO (2) Electrochemical Properties. The energy band gap (Eg), HOMO and LUMO are three imperative electrical parameters of electroluminescent materials. Herein, cyclic voltammetry measurements were carried out in order to better explain the pronounced fluorescence bathochromic shift and probe into the correlation between optical properties and electrical structures. A glassy carbon electrode was coated with compounds 3-7 and 3c-7c, the Pt wire electrode and Ag/AgNO3 electrode were utilized as the counter electrode and reference electrode, respectively. The electrical parameters and CV curves of as-synthesized compounds are illustrated in Table 1 and Figure S56-57. For example, the oxidation onset values of compounds 3, 3c, 4 and 4c versus Ag/AgNO3 electrode were estimated to be 0.91, 0.81, 0.88 and 0.79 V, respectively. The energy band gaps (Eg) of 3, 3c, 4 and 4c were calculated to be 3.17, 2.67, 3.20 and 2.64 eV, derived from the intersection of the UV spectra and the PL spectra. It can be obviously seen that oxidized compounds 3c-7c have lower HOMO energy values and narrower band gaps compared with compounds 3-7, showing that oxidative cyclization can narrower band gaps because of the extended -electron delocalization. The above measured values are in good accordance with measurements of optical properties and increasing molecular planarity.

Figure 10. Photos of 3 of the pristine powder and the ground powder under room light (a) and 365nm UV light (b). Photos of 4 of the pristine powder and the ground powder under room light (c) and 365nm UV light (d). PL spectra of 3 (e) and 4 (f) of the pristine powder and the ground powder. Piezofluorochromism. In recent years, novel stimuli-responsive luminescent materials with color-variable properties have aroused much interest in academia due to their tremendous potentials to be applied in fields of memory materials, sensors, security inks and so on.42-46 Generally, when treated with pressing, grinding, shearing or other mechanical stimulus, these smart luminescent materials will show luminescence behaviors dependent on molecular structures and this phenomenon is called piezochromic luminescence.47 Small organic molecules,48-50 polymers and organometallics are three main types of luminescent materials exhibiting piezofluorochromism. Among them, small organic molecules are particularly intriguing on account of their ability to switch emissions under the external stimuli and demonstrate reversibility through thermal or solvent annealing. It is easier to regulate emission colors of luminescent materials by changing the molecular packing pattern than altering molecular chemical structures. And it has been reported that some kinds of luminogens exhibit piezofluorochromism.51-53 Three main explanations for the piezochromic luminescence consist of liquid crystalline transitions, conformational alternations of crystal structures and morphology changes between amorphous and crystal states. In our work, we explored whether as-synthesized compounds 3-7 will exhibit piezofluorochromism under the external pressure. It was found that compounds 3 (Z-) and 4 (Z-) showed distinct piezofluorochromic behaviors by grinding for some time. While, their corresponding isomers, 6 (E-) and 7 (E-) exhibited no such behaviors because of more twisted molecular conformations. The as-synthesized compound 3 (Z-) was a white solid and emitted blue emission under the irradiation of a UV lamp. Intriguingly, after being ground with a mortar and a pestle for a while, it changed to a pale-yellow powder and exhibited bluishgreen emission under the irradiation of a UV lamp, showing piezochromic effect, vividly depicted in Figure 10a and 10b. The piezofluorochromism of compound 3 (Z-) can be further confirmed by the obvious change of its PL emission before and after grinding. As displayed in Figure 10e, The PL spectrum of as-obtained solid displayed a red shift from 454 to 486 nm, revealing a morphological change from crystalline to amorphous state. For an AIE luminogen, its amorphous state often shows a red-shift emission compared with crystalline state, resulted from a more



twisted molecular conformation in the crystalline phase than in the amorphous phase.54 Similarly, compound 4 (Z-) changed from a white solid to a yellow powder after grinding, and exhibited bluishgreen emission under the irradiation of UV light (Figure 10c and 10d). In addition, its PL spectrum showed a red shift from 426nm to 487nm (Figure 10f), suggesting piezochromic effect. Interestingly, the quantum yields of 3 and 4 after grinding both increased, resulting in the enhanced luminescence brightness. For compound 3, the quantum yields of the powders before and after grinding were 45% and 54%, respectively. For compound 4, the quantum yields of the powders before and after grinding were separately 41% and 52%. The reason may be that the molecules after grinding likely adopt planar conformations, thus reducing the vibrational or rotational relaxations. To better understand the mechanism of the piezochromic behavior, we explored the powder XRD and DSC performances of compound 3 (Z-) before and after grinding. From XRD patterns of compounds 3 (Z-) (Figure S51), it can be seen that the pristine sample showed sharp and intensive reflections, suggesting a crystalline state. While, the ground powder displayed weak reflections which indicated an amorphous state. And DSC curves showed that the ground state of 3 (Z-) has an endothermic peak located at 98 °C before melting, however, no endothermic peak was detected in the DSC thermogram of the pristine sample (Figure S52). This further indicated that the crystalline state can be altered into an amorphous state by grinding. Surprisingly, we found bright mechanoluminescence of the pure TPE molecule after other TPEs with mechanoluminescence reported.55-56 Therefore, the mechanoluminescence of compounds 3-7 is being investigated, which will be discussed in detail later in our work.

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exceptional properties. For example, it allows the device to operate with a low working voltage, which can effectively reduce the generated heat during operation.66-67 In addition, ion gel with high capacitance can be prepared under low temperature. Furthermore, when fabricated on plastic substrates, FETs with ion gel used as dielectric layers can exhibit mechanical flexibility, which has been reported in our previous work.68 Generally, it is a good choice to choose ion gel as the dielectric layer of the FET device. Figure 11a shows the 3D model structure of thin film top-gate FETs based on graphene-like molecules. The CH2Cl2 solutions of 4c and 5c were uniformly spin-coated on treated Si/SiO2 substrates to be semiconductors of OFET devices. The detailed process of fabricating FETs can be referred in the former characterization section. For p-type OFETs, a conductive channel will form due to the accumulation of holes at the organic and dielectric layers interface when a negative gate voltage is biased. In order to keep the device in operation the gate voltage needs to be larger than the threshold voltage because deep traps of the organic and dielectric layers interface could confine some induced carriers. Figure 11c and 11e displayed typical transfer characteristic curves (ID-VG) of FETs with 4c and 5c, respectively. As vital parameters of FET devices, the charge carrier mobility () and threshold voltage (Vth) were determined from the saturated regime of the transfer plot on the basis of the following equation: IDS =

𝑊 2𝐿 Ci(VG -

Vth)2

(3)

Where IDS is the drain-source current, Ci is the specific capacitance of the dielectric, measured to be 20 F/cm2 in this work. W is the channel width (800 and 600 m) and L is the channel length (1000 m). The Vth values of the devices based on 4c and 5c were evaluated to be -0.5V and -0.79V from a linear relationship between the |IDS|1/2 versus |VG| curve measured at VDS=3V. Table 2. The mobility, , the measurement reliability, r, the maximum power density, Pmax and the maximum current density, 𝒋𝒎𝒂𝒙 𝑺𝑫 of 4c and 5c. compound



r

(cm2V-1s-1)

Figure 11. (a)The geometric structure of top-gated FETs fabricated with ion gel dielectrics. Transfer (b) and output (c) characteristics of FET devices based on 4c. Transfer (d) and output (e) characteristics of FET devices based on 5c. OFET Characterization. Nowadays, a great deal of polymers and conjugated molecules have been widely applied in the field of FETs and exhibited excellent performances.57-65 Herein, graphenelike molecules 4c and 5c were utilized to be semiconductor layers in OFET devices on purpose of exploring their charge transporting characteristics. Conventional dielectrics (SiO2, ZrO2 or HfO2) are usually used as gate dielectrics of FET devices. However, in this work, ion gel was utilized to be the gate dielectric due to its

Pmax

𝑗𝑚𝑎𝑥 𝑆𝐷

(W/cm2)

(kA/cm2)

4c

0.92

65%

0.103

0.206

5c

1.14

60%

0.085

0.226

The  for 4c is 0.92cm2V-1s-1 with an Ion/Ioff of 2.7104. And  for 5c is 1.14 cm2V-1s-1 with an Ion/Ioff of 1.52104. According to previous report,69 there are some pitfalls when calculating the values of , and the measurement reliability, r, the maximum power density, Pmax and the maximum current density, 𝑗𝑚𝑎𝑥 𝑆𝐷 are three crucial parameters to evaluate the accuracy of . Herein, we obtained values of r, Pmax and 𝑗𝑚𝑎𝑥 𝑆𝐷 of 4c and 5c (Table 2), showing the values of  in this work are authentic and reliable. Detailed processes of calculation can be found in Supporting Information. Therefore, excellent mobility, high Ion/Ioff and low operating voltage (< 5V) promote the graphene-like molecules 4c and 5c to be well applied to OFETs. According to the transfer characteristic curves and gate current curves of 4c and 5c, the gate leakage is too small to have an impact on the drain current. (Figure S59). In addition, output characteristic curves (ID-VD) of FETs with 4c and 5c were separately shown in Figure 11b and 11d, clearly confirming the p-channel characteristics of FETs based on 4c and 5c. In Figure 11b and 11d, the hysteresis of the transfer curves may


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be caused by the mobile ions in PMMA of the ion gel. Because the ion entangles with the polymer chain will accumulate at the interface between the dielectric layer and the semiconductor layer under an operating voltage.70-71 CONCLUSIONS In summary, we have designed and synthesized configurationcontrollable E/Z isomers based on TPEs via Suzuki reaction in this work. We explored the photoinduced conformation changes of E/Z isomers under the irradiation of a UV lamp and their AIE effect. Red-shifts of 66nm from 6 (E-) to 3 (Z-) and 58nm from 7 (E-) to 4 (Z-) were observed on the PL emission spectra. Z-isomer showed longer fluorescence lifetime compared with E-isomer. Z-isomers 3 and 4 exhibited piezofluorochromism under grinding while Eisomers 6 and 7 showed no such behaviors. E-isomer has better thermal stability than Z-isomer. Then, graphene molecules based on TPEs were successfully obtained with the FeCl3/CH3NO2 system. The oxidized products of E- and Z-isomer showed negligible differences on the PL emission spectra, because the effective conjugated lengths of oxidized E- and Z-isomers were extended. Intriguingly, it can be seen by naked eyes that ring-closed structures emitted varying colors with varying oxidation time. That is to say, multicolor graphene molecules with tunable emission were successfully designed and synthesized with the Scholl reaction. Finally, FET devices based on 4c and 5c were fabricated and characterized. Their mobilities were calculated to be 0.92 and 1.14cm-2V-1s-1 at low operating voltages, respectively, showing good electrical performances.

ASSICATED CONTENT Supporting Information Synthetic methods and characterizations of all compounds (MADIF-TOF, 1H and 13C NMR); NOESY and COSY NMR spectroscopy of isomers; IR and Raman spectra of isomers; IR spectra of 3c and 6c; TGA data of 3c and 4c; AIE spectrum of 5; 1H NMR spectra changes of isomers, 3 and 6, induced by UV light; XRD patterns of 3; DSC data of 3; molecular orbit amplitude plots of HOMO and LUMO energy levels of 5, 5c, 6, 6c, 7 and 7c; CV curves of 3-7 and 3c-7c; crystal data of 5; retention time of GC-MS of isomers; the PL lifetime of 3, 4, 6, 7; the detailed processes of calculation for OFETs. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Author *E-mail: [email protected]. Tel: +86 21-31243836 Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS This work was financially supported by the National Natural Science Foundation of China (21274027 and 20974022) and Natural Science Foundation of Shanghai (18ZR1402300). The computation work was supported by the A*STAR Computational Resource Centre through the use of its high performance computing facilities. The FET devices were fabricated and measured in Fudan Nanofabrication Laboratory.

REFERENCES (1) Faulkner, A. D.; Kaner, R. A.; Abdallah, Q. M. A.; Clarkson, G.; Fox, D. J.; Gurnani, P.; Howson, S. E.;

Phillips, R. M.; Roper, D. I.; Simpson, D. H.; Scott, P. Asymmetric Triplex Metallohelices with High and Selective Activity against Cancer Cells. Nat. Chem. 2014, 6, 797-803. (2) Nakamura, K.; Greenwood, A.; Binder, L.; Bigio, E. H.; Denial, S.; Nicholson, L.; Zhou, X. Z.; Lu, K. P. Proline Isomer-Specific Antibodies Reveal the Early Pathogenic Tau Conformation in Alzheimer's Disease. Cell 2012, 149, 232-244. (3) Guo, S.; Matsukawa, K.; Miyata, T.; Okubo, T.; Kuroda, K.; Shimojima, A. Photoinduced Bending of SelfAssembled Azobenzene-Siloxane Hybrid. J. Am. Chem. Soc. 2015, 137, 15434-15440. (4) van Dijken, D. J.; Kovaricek, P.; Ihrig, S. P.; Hecht, S. Acylhydrazones as Widely Tunable Photoswitches. J. Am. Chem. Soc. 2015, 137, 14982-14991. (5) Wu, J.-S.; Lin, C.-T.; Wang, C.-L.; Cheng, Y.-J.; Hsu, C.-S. New Angular-Shaped and Isomerically Pure Anthradithiophene with Lateral Aliphatic Side Chains for Conjugated Polymers: Synthesis, Characterization, and Implications for Solution-Prossessed Organic Field-Effect Transistors and Photovoltaics. Chem. Mater. 2012, 24, 2391-2399. (6) Song, D.; Schmider, H.; Wang, S. Isomerism of Bis(7azaindolyl)methane. Org. Lett. 2002, 4, 4049-4052. (7) Chehal, N. K.; Budzelaar, P. H. M.; Hultin, P. G. E-Z Isomerization in Suzuki Cross-couplings of Haloenones: Ligand Effects and Evidence for a Separate Catalytic Cycle. Org. Biomol. Chem. 2018, 16, 1134-1143. (8) Emoto, A.; Uchida, E.; Fukuda, T. Optical and Physical Applications of Photocontrollable Materials: AzobenzeneContaining and Liquid Crystalline Polymers. Polymers 2012, 4, 150-186. (9) Li, W.; Wang, S.; Zhang, Y.; Gao, Y.; Dong, Y.; Zhang, X.; Song, Q.; Yang, B.; Ma, Y.; Zhang, C. Highly Efficient Luminescent E- and Z-isomers with Stable Configurations under Photoirradiation Induced by Their Charge Transfer Excited States. J. Mater. Chem. C 2017, 5, 8097-8104. (10) Mahimwalla, Z.; Yager, K. G.; Mamiya, J.-i.; Shishido, A.; Priimagi, A.; Barrett, C. J. Azobenzene Photomechanics: Prospects and Potential Applications. Polym. Bull. 2012, 69, 967-1006. (11) Nakano, M.; Niimi, K.; Miyazaki, E.; Osaka, I.; Takimiya, K. Isomerically Pure Anthra[2,3-b:6,7-b']-difuran (anti-ADF), -dithiophene (anti-ADT), and -diselenophene (anti-ADS): Selective Synthesis, Electronic Structures, and Application to Organic Field-Effect Transistors. J. Org. Chem. 2012, 77, 8099-8111. (12) Yanai, N.; Mori, T.; Shinamura, S.; Osaka, I.; Takimiya, K. Dithiophene-Fused Tetracyanonaphthoquinodimethanes (DT-TNAPs): Synthesis and Characterization of pi-Extended Quinoidal Compounds for n-Channel Organic Semiconductor. Org. Lett. 2014, 16, 240-243. (13) Chung, J. W.; Yoon, S.-J.; An, B.-K.; Park, S. Y. HighContrast On/Off Fluorescence Switching via Reversible E– Z Isomerization of Diphenylstilbene Containing the αCyanostilbenic Moiety. J. Phys. Chem. C 2013, 117, 1128511291. (14) Liu, N.; Liu, H.; Zhu, S.; Giessen, H.



Stereometamaterials. Nature Photonics 2009, 3, 157-162. (15) Liu, Y.; Shan, T.; Yao, L.; Bai, Q.; Guo, Y.; Li, J.; Han, X.; Li, W.; Wang, Z.; Yang, B.; Lu, P.; Ma, Y. Isomers of Pyrene-Imidazole Compounds: Synthesis and Configuration Effect on Optical Properties. Org. Lett. 2015, 17, 6138-6141. (16) Wei, P.; Zhang, J. X.; Zhao, Z.; Chen, Y.; He, X.; Chen, M.; Gong, J.; Sung, H. H.; Williams, I. D.; Lam, J. W. Y.; Tang, B. Z. Multiple yet Controllable Photoswitching in a Single AIEgen System. J. Am. Chem. Soc. 2018, 140, 19661975. (17) Dong, F.; Li, J.; Chankvetadze, B.; Cheng, Y.; Xu, J.; Liu, X.; Li, Y.; Chen, X.; Bertucci, C.; Tedesco, D.; Zanasi, R.; Zheng, Y. Chiral Triazole Fungicide Difenoconazole: Absolute Stereochemistry, Stereoselective Bioactivity, Aquatic Toxicity, and Environmental Behavior in Vegetables and Soil. Environ. Sci.Technol. 2013, 47, 33863394. (18) Chaney, S. G.; Campbell, S. L.; Bassett, E.; Wu, Y. Recognition and Processing of Cisplatin- and OxaliplatinDNA Adducts. Critical Reviews in Oncology/Hematology 2005, 53, 3-11. (19) Yuan, Y.; Zhang, C.; Liu, B. A Platinum Prodrug Conjugated with a Photosensitizer with AggregationInduced Emission (AIE) Characteristics for Drug Activation Monitoring and Combinatorial PhotodynamicChemotherapy against Cisplatin Resistant Cancer Cells. Chem. Commun. 2015, 51, 8626-8629. (20) Arlt, M.; Scheffler, A.; Suske, I.; Eschner, M.; Saragi, T. P.; Salbeck, J.; Fuhrmann-Lieker, T. Bipolar Redox Behaviour, Field-Effect Mobility and Transistor Switching of the Low-molecular Azo Glass AZOPD. Phys. Chem. Chem. Phys. 2010, 12, 13828-13834. (21) Luo, J.; Xie, Z.; Lam, J. W. Y.; Cheng, L.; Chen, H.; Qiu, C.; Kwok, H. S.; Zhan, X.; Liu, Y.; Zhu, D.; Tang, B. Z. Aggregation-Induced Emission of 1-methyl-1,2,3,4,5pentaphenylsilole. Chem. Commun. 2001, 1740-1741. (22) Du, X.; Qi, J.; Zhang, Z.; Ma, D.; Wang, Z. Y. Efficient Non-Doped Near Infrared Organic Light-Emitting Devices Based on Fluorophores with Aggregation-Induced Emission Enhancement. Chem. Mater. 2012, 24, 2178-2185. (23) Huang, J.; Jiang, Y.; Yang, J.; Tang, R.; Xie, N.; Li, Q.; Kwok, H. S.; Tang, B. Z.; Li, Z. Construction of Efficient Blue AIE Emitters with Triphenylamine and TPE Moieties for Non-Doped OLEDs. J. Mater. Chem. C 2014, 2, 20282036. (24) Liu, Y.; Chen, S.; Lam, J. W. Y.; Lu, P.; Kwok, R. T. K.; Mahtab, F.; Kwok, H. S.; Tang, B. Z. Tuning the Electronic Nature of Aggregation-Induced Emission Luminogens with Enhanced Hole-Transporting Property. Chem. Mater. 2011, 23, 2536-2544. (25) Tang, X.; Yao, L.; Liu, H.; Shen, F.; Zhang, S.; Zhang, H.; Lu, P.; Ma, Y. An Efficient AIE-Active Blue-Emitting Molecule by Incorporating Multifunctional Groups into Tetraphenylsilane. Chem. Eur. J 2014, 20, 7589-7592. (26) Chen, S.; Hong, Y.; Liu, Y.; Liu, J.; Leung, C. W.; Li, M.; Kwok, R. T.; Zhao, E.; Lam, J. W.; Yu, Y.; Tang, B. Z. Full-Range Intracellular pH Sensing by an AggregationInduced Emission-Active two-Channel Ratiometric Fluorogen. J. Am. Chem. Soc. 2013, 135, 4926-4929.

Page 10 of 13

(27) Chen, S.; Liu, J.; Liu, Y.; Su, H.; Hong, Y.; Jim, C. K. W.; Kwok, R. T. K.; Zhao, N.; Qin, W.; Lam, J. W. Y.; Wong, K. S.; Tang, B. Z. An AIE-Active Hemicyanine Fluorogen with Stimuli-Responsive Red/Blue Emission: Extending the pH Sensing Range by “Switch + Knob” Effect. Chem. Sci. 2012, 3, 1804-1809. (28) Guo, F.; Gai, W. P.; Hong, Y.; Tang, B. Z.; Qin, J.; Tang, Y. Aggregation-Induced Emission Fluorogens as Biomarkers to Assess the Viability of Microalgae in Aquatic Ecosystems. Chem. Commun. 2015, 51, 17257-17260. (29) Liu, L.; Zhang, G.; Xiang, J.; Zhang, D.; Zhu, D. Fluorescence "Turn On" Chemosensors for Ag+ and Hg+ Based on Tetraphenylethylene Motif Featuring Adenine and Thymine Moieties. Org. Lett. 2008, 10, 4581-4584. (30) Wang, S.; Zhu, Z.; Wei, D.; Yang, C. Tetraphenylethene-based Zn Complexes for the Highly Sensitive Tetection of Single-Stranded DNA. J. Mater. Chem. C 2015, 3, 11902-11906. (31) Xu, L.; Zhu, Z.; Wei, D.; Zhou, X.; Qin, J.; Yang, C. Amino-Modified Tetraphenylethene Derivatives as Nucleic Acid Stain: Relationship Between the Structure and Sensitivity. ACS Appl. Mater. Interfaces 2014, 6, 1834418351. (32) Xu, L.; Zhu, Z.; Zhou, X.; Qin, J.; Yang, C. A Highly Sensitive Nucleic Acid Stain Based on Amino-Modified Tetraphenylethene: The Influence of Configuration. Chem. Commun. 2014, 50, 6494-6497. (33) Zhang, M.; Yin, X.; Tian, T.; Liang, Y.; Li, W.; Lan, Y.; Li, J.; Zhou, M.; Ju, Y.; Li, G. AIE-Induced Fluorescent Vesicles Containing Amphiphilic Binding Pockets and the FRET Triggered by Host-Guest Chemistry. Chem. Commun. 2015, 51, 10210-10213. (34) Fang, X.; Zhang, Y.-M.; Chang, K.; Liu, Z.; Su, X.; Chen, H.; Zhang, S. X.-A.; Liu, Y.; Wu, C. Facile Synthesis, Macroscopic Separation, E/Z Isomerization, and Distinct AIE properties of Pure Stereoisomers of an OxetaneSubstituted Tetraphenylethene Luminogen. Chem. Mater. 2016, 28, 6628-6636. (35) Liang, J.; Shi, H.; Kwok, R. T. K.; Gao, M.; Yuan, Y.; Zhang, W.; Tang, B. Z.; Liu, B. Distinct Optical and Kinetic Responses From E/Z Isomers of Caspase Probes with Aggregation-Induced Emission Characteristics. J. Mater. Chem. B 2014, 2, 4363-4370. (36) Sheldrick, G. M. A Short History of SHELX. Acta Cryst. 2008, A64, 112-122. (37) Simpson, C. D.; Mattersteig, G.; Martin, K.; Gherghel, L.; Bauer, R. E.; Räder, H. J.; Müllen, K. Nanosized Molecular Propellers by Cyclodehydrogenation of Polyphenylene Dendrimers. J. Am. Chem. Soc. 2004, 126, 3139-3147. (38) Zhao, Z.; Chen, S.; Shen, X.; Mahtab, F.; Yu, Y.; Lu, P.; Lam, J. W. Y.; Kwok, H. S.; Tang, B. Z. AggregationInduced Emission, Self-Assembly, and Electroluminescence of 4,4'-Bis(1,2,2-triphenylvinyl)biphenyl. Chem. Commun. 2010, 46, 686-688. (39) Vyas, V. S.; Rathore, R. Preparation of a Tetraphenylethylene-Based Emitter: Synthesis, Structure and Optoelectronic Properties of Tetrakis(pentaphenylphenyl)ethylene. Chem. Commun.


Page 11 of 13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


2010, 46, 1065-1067. (40) Hong, Y.; Chen, S.; Leung, C. W.; Lam, J. W.; Liu, J.; Tseng, N. W.; Kwok, R. T.; Yu, Y.; Wang, Z.; Tang, B. Z. Fluorogenic Zn(II) and Chromogenic Fe(II) Sensors Based on Terpyridine-Substituted Tetraphenylethenes with Aggregation-Induced Emission Characteristics. ACS Appl. Mater. Interfaces 2011, 3, 3411-3418. (41) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision A.02; Gaussian: Wallingford, CT, 2009. (42) Dou, C.; Chen, D.; Iqbal, J.; Yuan, Y.; Zhang, H.; Wang, Y. Multistimuli-Responsive Benzothiadiazole-Cored Phenylene Vinylene Derivative with Nanoassembly Properties. Langmuir 2011, 27, 6323-6329. (43) Kishimura, A.; Yamashita, T.; Yamaguchi, K.; Aida, T. Rewritable Phosphorescent Paper by the Control of Competing Kinetic and Thermodynamic Self-Assembling Events. Nat. Mater. 2005, 4, 546-549. (44) Ning, Z.; Chen, Z.; Zhang, Q.; Yan, Y.; Qian, S.; Cao, Y.; Tian, H. Aggregation-Induced Emission (AIE)-Active Starburst Triarylamine Fluorophores as Potential Nondoped Red Emitters for Organic Light-Emitting Diodes and Cl2 Gas Chemodosimeter. Adv. Funct. Mater. 2007, 17, 3799-3807. (45) Sagara, Y.; Kato, T. Brightly Tricolored Mechanochromic Luminescence From a Singleluminophore Liquid Crystal: Reversible Writing and Erasing of Images. Angew. Chem. Int.Ed. 2011, 50, 91289132. (46) Teng, M.; Jia, X.; Chen, X.; Ma, Z.; Wei, Y. Mechanochromic Luminescent Property of a PolypeptideBased Dendron. Chem. Commun. 2011, 47, 6078-6080. (47) Sagara, Y.; Kato, T. Mechanically Induced Luminescence Changes in Molecular Assemblies. Nat. Chem. 2009, 1, 605-6010. (48) Zhang, X.; Chi, Z.; Li, H.; Xu, B.; Li, X.; Zhou, W.; Liu, S.; Zhang, Y.; Xu, J. Piezofluorochromism of an Aggregation-Induced Emission Compound Derived from Tetraphenylethylene. Chem. Asian J. 2011, 6, 808–811. (49) Zhou, X.; Li, H.; Chi, Z.; Zhang, X.; Zhang, J.; Xu, B.; Zhang, Y.; Liu, S.; Xu, J. Piezofluorochromism and Morphology of a New Aggregation-Induced Emission Compound Derived from Tetraphenylethylene and

Carbazole. New J. Chem., 2012, 36, 685–693. (50) Xu, B.; Chi, Z.; Zhang, J.; Zhang, X.; Li, H.; Li, X.; Liu, S.; Zhang, Y.; Xu, J. Piezofluorochromic and Aggregation-Induced-Emission Compounds Containing Triphenylethylene and Tetraphenylethylene Moieties. Chem. Asian J. 2011, 6, 1470–1478. (51) Zhang, G.; Lu, J.; Sabat, M.; Fraser, C. L. Polymorphism and Reversible Mechanochromic Luminescence for Solid-State Difluoroboron Avobenzone. J. Am. Chem. Soc. 2010, 132, 2160-2162. (52) Yang, Z.; Chi, Z.; Mao, Z.; Zhang, Y.; Liu, S.; Zhao, J.; Aldred, M. P.; Chi, Z. Recent Advances in MechanoResponsive Luminescence of Tetraphenylethylene Derivatives with Aggregation-Induced emission Properties. Mater. Chem. Front. 2018, 2, 861-890. (53) Zhao, Y.; Gao, H.; Fan, Y.; Zhou, T.; Su, Z.; Liu, Y.; Wang, Y. Thermally Induced Reversible Phase Transformations Accompanied by Emission Switching Between Different Colors of Two Aromatic-Amine Compounds. Adv. Mater. 2009, 21, 3165-3169. (54) Kim, H. N.; Guo, Z.; Zhu, W.; Yoon, J.; Tian, H. Recent Progress on Polymer-Based Fluorescent and Colorimetric Chemosensors. Chem. Soc. Rev. 2011, 40, 79-93. (55) Xu, B.; He, J.; Mu, Y.; Zhu, Q.; Wu, S.; Wang, Y.; Zhang, Y.; Jin, C.; Lo, C.; Chi, Z.; Lien, A.; Liu, S.; Xu, J. Very Bright Mechanoluminescence and Remarkable Mechanochromism Using a Tetraphenylethene Derivative with Aggregation-Induced Emission. Chem. Sci. 2015, 6, 3236-3241. (56) Xie, Y.; Tu, J.; Zhang, T.; Wang, J.; Xie, Z.; Chi, Z.; Peng, Q.; Li, Z. Mechanoluminescence From Pure Hydrocarbon AIEgen. Chem. Commun. 2017, 53, 1133011333. (57) Wang, C.; Ren, X.; Xu, C.; Fu, B.; Wang, R.; Zhang, X.; Li, R.; Li, H.; Dong, H.; Zhen, Y.; Lei, S.; Jiang, L.; Hu, W. N-Type 2D Organic Single Crystals for HighPerformance Organic Field-Effect Transistors and NearInfrared Phototransistors. Adv. Mater. 2018, 30, 17062601706268. (58) Lei, T.; Xia, X.; Wang, J.; Liu, C.; Pei, J. "Conformation Locked" Strong Electron-Deficient Poly(ρPhenylene Vinylene) Derivatives for Ambient-Stable nType Field-Effect Transistors: Synthesis, Properties, and Effects of Fluorine Substitution Position. J. Am. Chem. Soc. 2014, 136, 2135-2141. (59) Schweicher, G.; Lemaur, V.; Niebel, C.; Ruzié, C.; Diao, Y.; Goto, O.; Lee, W. Y.; Kim, Y.; Arlin, J. B.; Karpinska, J.; Kennedy, A. R.; Parkin, S. R.; Olivier, Y.; Mannsfeld, S. C. B.; Cornil, J.; Geerts, Y. H.; Bao, Z. Bulky End-Capped [1]Benzothieno[3,2-b]benzothiophenes: Reaching High-Mobility Organic Semiconductors by Fine Tuning of the Crystalline Solid-State Order. Adv. Mater. 2015, 27, 3066-3072. (60) Zhao, Z.; Yin, Z.; Chen, H.; Zheng, L.; Zhu, C.; Zhang, L.; Tan, S.; Wang, H.; Guo, Y.; Tang, Q.; Liu, Y. HighPerformance, Air-Stable Field-Effect Transistors Based on Heteroatom-Substituted NaphthalenediimideBenzothiadiazole Copolymers Exhibiting Ultrahigh Electron Mobility Up to 8.5 cm V-1 s-1. Adv. Mater. 2017,



Page 12 of 13

29, 1602410-1602416. (61) Li, L.; Gao, P; Schuermann, K. C.; Ostendorp, S.; Wang, W.; Du, C.; Lei, Y.; Fuchs, H.; Cola, L. D.; Müllen, K.; Chi, L. Controllable Growth and Field-Effect Property of Monolayer to Multilayer Microstripes of an Organic Semiconductor. J. Am. Chem. Soc. 2010, 132, 8807-8809. (62) Wang, Z.; Liu, Z.; Ning, L.; Xiao, M.; Yi, Y.; Cai, Z.; Sadhanala, A.; Zhang, G.; Chen, W.; Sirringhaus, H.; Zhang, D. Charge Mobility Enhancement for Conjugated DPPSelenophene Polymer by Simply Replacing One Bulky Branching Alkyl Chain with Linear One at Each DPP Unit. Chem. Mater. 2018, 30, 3090-3100. (63) Ge, F.; Liu, Z.; Lee, S. B.; Wang, X.; Zhang, G.; Lu, H.; Cho, K.; Qiu, L. Bar-Coated Ultrathin Semiconductors from Polymer Blend for One-Step Organic Field-Effect Transistors. ACS Appl. Mater. Interfaces 2018, 10, 2151021517. (64) Xu, H.; Zhou, Y.; Zhang, J.; Jin, J.; Liu, G.; Li, Y.; Ganguly, R.; Huang, L.; Xu, W.; Zhu, D.; Huang, W.; Zhang, Q. Polymer-Assisted Single Crystal Engineering of Organic Semiconductors To Alter Electron Transport. ACS Appl. Mater. Interfaces 2018, 10, 11837-11842. (65) Wen, J.; Xiao, C.; Lv, A.; Hayashi, H.; Zhang, L. Tuning the Electronic Properties of Thiophene-Annulated NDIs: the Influence of the Lateral Fusion Position. Chem. Commun. 2018, 54, 5542-5545. (66) Cho, J. H.; Lee, J.; Xia, Y.; Kim, B.; He, Y.; Renn, M. J.; Lodge, T. P.; Frisbie, C. D. Printable Ion-Gel Gate Dielectrics for Low-Voltage Polymer Thin-Film Transistors on Plastic. Nat. Mater. 2008, 7, 900-906. (67) Kim, B. J.; Jang, H.; Lee, S. K.; Hong, B. H.; Ahn, J. H.; Cho, J. H. High-Performance Flexible Graphene Field Effect Transistors with Ion Gel Gate Dielectrics. Nano Lett. 2010, 10, 3464-3466. (68) Huang, Y.; Huang, W.; Yang, J.; Ma, J.; Chen, M.; Zhu, H.; Wang, W. The Synthesis, Characterization and Flexible OFET Application of Three (Z)-1,2-bis(4-(tertbutyl)phenyl)ethane Based Copolymers. Polym. Chem. 2016, 7, 538-545. (69) Choi, H. H.; Cho, K.; Frisbie, C. D.; Sirringhaus, H.; Podzorov, V. Critical Assessment of Charge Mobility Extraction in FETs. Nat. Mater. 2017, 17, 2-7. (70) Egginger, M.; Bauer, S.; Schwödiauer, R.; Neugebauer, H.; Sariciftci, N.S. Current Versus Gate Voltage Hysteresis in Organic Field Effect Transistors. Monatsh Chem 2009, 140,735–750. (71) Huang, W.; Shi, W.; Han, S.; Yu, J. Hysteresis Mechanism and Control in Pentacene Organic Field-Effect Transistors with Polymer Dielectric. Aip Advances 2013, 3, 052122.


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Z Isomers Based on Tetraphenylethene

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