(9-Anthryl)vinyl(9-phenanthryl)vinylbenzene Position Isomers

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The Journal of Physical Chemistry

(9-Anthryl)vinyl(9-phenanthryl)vinylbenzene Position Isomers: Intriguing Effects of Molecular Configuration on Polymorphism, Solvatochromism,

and

Aggregation-Induced

Emission

Properties Ye-Xin Li,* Jin-Xing Qiu, Jin-Ling Miao, Zhen-Wei Zhang, Xiao-Feng Yang, and Guo-Xin Sun*

School of Chemistry and Chemical Engineering, University of Jinan, 250022, Jinan, China

ABSTRACT:

Three

[(9-anthryl)vinyl][(9-phenanthryl)vinyl]benzene

(APB)

position isomers were synthesized and compared. The molecular configuration exhibits an extraordinary ability to affect polymorphism probability, unexpected solvatochromism, and aggregation-induced emission property. With the substitution changing from para-, ortho-, to meta-position, the polymorph number changes from 1, 2, to 3. Both 1,2-APB and 1,3-APB display a temperature-induced crystal-to-crystal phase transition. Furthermore, a pair of concomitant conformational polymorphs were obtained for 1,3-APB. Crystal structure analyses reveal that the steric hindrance between the two substituents leads to different molecular conformation and packing pattern. The unexpected solvatochromism is attributed to the strong electron-withdrawing ability of anthracene against phenanthrene, which produces permanent dipole moment. The solvatochromic degree is determined by the 1

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conjugative effect which varies with substitution position. 1,4-APB displays the most remarkable solvatochromic effect. Furthermore, it shows a totally different emission decay dynamics from 1,2-APB and 1,3-APB in polar solvents. Interestingly, the solution fluorescence quantum yields of these three isomers all increase with increased solvent polarity, displaying a negative solvatokinetic effect. Both 1,2-APB and 1,4-APB display an aggregation-induced emission enhancement. Though 1,3-APB is quenched in the solid state, it emits most efficiently amongst these three isomers either in solution or in solid state. The effect of the medium environment on the

radiative

process

plays

a

vital

role

in

determining

their

different

aggregation-induced emission behaviours.

INTRODUCTION Organic fluorescence materials have been the hot topic for their wide applications in data storage,1 sensor,2 photoswitch,3 organic light-emitting diode (OLED),4 and organic light-emitting transistor (OLET) devices.5 Usually these materials are used as solid state. Their molecular structure and intermolecular packing collectively determine the solid optoelectronic properties. Possibly due to excitonic coupling and formation of such species as excimer and exciplex, most organic chromophores are unfortunately quenched in the solid state against the corresponding solution. At the beginning of this new century, Tang and co-workers and Park and co-workers reported abnormal material systems with an aggregation-induced emission (AIE) behavior, respectively.6,7 This shed new light on the development of organic fluorescence materials. Thereafter many AIE-active materials are reported and the 2


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corresponding applications in optoelectronic devices, sensors, biomedical imaging, and smart materials are accordingly flourishing.8 However, some AIE-active materials are still weakly emissive in the solid state with a low quantum yield less than 10%.9-16 Compared to the solution whose fluorescence is commonly related to the single molecule, the aggregate emission is much more complicated. Molecular configuration, intermolecular interaction mode as well as strength, and morphology can all affect the solid emission colour and efficiency. Among them, the molecular spatial structure would be the first important factor, which could affect the aggregate packing and, furthermore, the optoelectronic properties. Therefore, studying the effects of molecular configuration on the aggregate packing and solid fluorescent property is still challenging and meaningful. The mechanochromic effects of AIE-active materials have recently gained much attention.17-19 The fluorescent properties of these materials can dynamically change in response to external force stimuli, which endows them with intelligent character. The corresponding mechanofluorochromic mechanism is usually attributed to the reversible switch between crystalline and amorphous states.1,17 During the grinding process, polycrystalline powder can be converted into amorphous solid. However, as shown in the powder X-ray diffraction patterns (XRD), this conversion is not complete in many cases.1,20-22 The crystalline and amorphous grains usually coexist in the ground powder, which may lead to the broadening of the emission spectrum. Furthermore, as molecules pack disorderly in the amorphous state, the effect of molecule conformation and packing style on the photophysical properties is difficult 3



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to elucidate.23 Comparatively, the interconversion between different polymorphs of one compound is more complete and controllable. The polymorph structure can be characterized by single-crystal X-ray diffraction. Thus the relationship between aggregate structure and fluorescent properties is easier to be investigated. Therefore, studying the polymorphism of AIE-active materials is constructive not only to elucidate the effect of aggregate structure on emission properties, but also to develop intelligent materials. Polymorphism means that one compound could crystallize in at least two distinct forms.24,25 For organic materials, the intermolecular interactions in solid state are weak Van der Waals' force or hydrogen bond. The molecular packing mode is sensitive to the external conditions such as solvent and temperature, allowing the possibility to form polymorphism. In these years, there is a growing awareness of the importance of polymorphism on the optoelectronic properties.21,26-30 However, obtaining a new polymorph during the research process is often regarded as an extra surprise. Polymorphism prediction from the viewpoint of molecular configuration is still difficult and challenging.24,31 Position isomerism means that a functional group or other substituent changes position on a parent structure. They have the same atomic composition but different molecular configuration. One typical position isomerism in the textbook is disubstituted benzene system, in which the two substituents can be arranged in ortho-, meta-, and para-positions. This difference in the substitution position can affect the optoelectronic properties.32-35 In our group, we aim to investigate the effect of substitution

position

on

the

photophysical

4


properties

of

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[(9-anthryl)vinyl](arylvinyl)benzene system. The H···H steric hindrance within the anthrylvinyl moiety may endow these materials with an AIE activity.36-38 In this contribution, we are focused on [(9-anthryl)vinyl][(9-phenanthryl)vinyl]benzene (APB) position isomers (Figure 1). Phenanthrene is an isomer of anthracene but attracts less attention. The molecular configuration difference between phenanthrene (nonliear) and anthracene (linear), in collaboration with substitution position, brings very interesting results: (1) from para-, ortho-, to meta-substitution, the obtained polymorph number changes from one, two, to three. A temperature-induced crystal-to-crystal phase transition was found for 1,2-APB and 1,3-APB; (2) in spite of the lack of typical donor-acceptor structural feature, they all display a solvatochromic effect and the substitution position determines the solvatochromic degree; (3) orthoand para-isomers show an aggregation-induced enhanced emission (AIEE) behavior, while the meta-isomer display an aggregation-caused quenching (ACQ) character.

1,3-APB

1,2-APB

1,4-APB

Figure 1. Molecular structure of three APB isomers.

RESULT AND DISCUSSION Synthesis and thermal property. Compounds 1,2-APB, 1,3-APB, and 1,4-APB were prepared by the Wittig or Horner-Wadsworth-Emmons reaction as yellow solids (Scheme S1). 1,2-APB and 1,3-APB solids were purified by recrystallization from 5



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ethyl acetate and chloroform, respectively. 1,4-APB solid was purified by chromatography. All the materials were characterized by NMR and MS spectral analyses. 1H NMR spectrum analysis shows that substitution position exerts a marked effect on the chemical shift of vinylic protons. For 1,3-APB and 1,4-APB, two pairs of doublets in the range of 7.0-7.4 ppm are ascribed to two vinylic protons, respectively. Judging from the peak shape and coupling constant, it can be concluded that these two protons should come from two different C=C bonds. The coupling constants of the vinylic protons (J =16.0 and 16.4 Hz) clearly indicate that both C=C bonds should be trans-configured,39 which is further proved by the following single crystal X-ray analyses. In comparison with 1,3-APB and 1,4-APB, the 1H NMR signals of 1,2-APB vinylic protons shift towards the low field and overlap with the aromatic proton signals.

Figure 2. TG (a) and DSC (b) curves of compounds 1,2-APB, 1,3-APB, and 1,4-APB. 6


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The thermal properties of these three compounds were investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses (Figure 2). All compounds exhibit good thermal stability and the 5% weight loss temperatures of 1,2-APB, 1,3-APB, and 1,4-APB are 318, 390, and 372 °C, respectively. Compound 1,4-APB displays an endothermic transition at 282 °C, corresponding to melting point, and there is no phase transition below the melting point. Interestingly, both 1,2-APB and 1,3-APB solids show a solid-to-solid phase transition below the melting point. The transition temperature is 192 °C for 1,2-APB and 204 °C for 1,3-APB. As the transition temperature is lower than the melting point and the decomposition temperature, these new polymorphs may be obtained by the thermal treatment of as-prepared powders.

Figure 3. XRD patterns of 1,2-APB polymorphs: (a) as-prepared powder (1,2-APB-α); (b) heating 1,2-APB-α at about 205 °C; (c) calculated from the crystal structure of sublimated crystals (1,2-APB-β). Polymorphism and crystal strucuture. Solution methods were firstly used to grow crystals. However, only 1,4-APB crystals, which were suitable for single-crystal X-ray diffraction, were obtained. Unfortunately, there are serious orientation disorders so that the structure is not accurately solved. Then, a physical vapour-transport 7



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technique was used and the crystals of these three compounds were successfully grown in a horizontal tube furnace. The crystal structure of 1,4-APB sublimated crystals is still unsuccessfully solved due to the serious orientation disorder. The powder XRD pattern of 1,4-APB sublimated crystals is nearly the same as that of the as-prepared powder (Figure S1), which indicates that no new polymorph is produced during the heating process. This is in accordance with the above DSC analysis. In contrast, the structures of 1,2-APB and 1,3-APB sublimated crystals were clearly determined. Interestingly, as shown in Figure 3 and Figure 4, the simulated XRD patterns from 1,2-APB and 1,3-APB crystal structures are both different from those of the as-prepared powders. This implies that, for 1,2-APB and 1,3-APB, new polymorph should be produced upon sublimation. The as-prepared powder is designated as α phase and the new polymorph is as β phase. In the beginning we took it for granted that only one new crystal phase of 1,3-APB was obtained.

Figure 4. XRD patterns of 1,3-APB polymorphs: (a) as-prepared powder (1,3-APB-α); (b) calculated from the crystal structure of sublimated crystals (1,3-APB-β); (c) heating 1,3-APB-α at about 215 °C; (d) crystals obtained via sublimation of 1,3-APB-α; (e) calculated from the crystal structure of 1,3-APB-γ. 8


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DSC analyses have shown that a temperature-induced phase transition exists in the as-prepared powders of 1,2-APB (1,2-APB-α) and 1,3-APB (1,3-APB-α) upon heating. Therefore, it is possible to equivalently obtain the new polymorph by heating the as-prepared powder other than sublimation. The as-prepared powders were then heated in a horizontal tube furnace under vacuum at a temperature which is higher than the phase transition temperature but lower than the sublimation temperature (about 205 °C for 1,2-APB and 215 °C for 1,3-APB). New polymorphs were equally obtained. For 1,2-APB, the XRD pattern of the heated powder is the same as the simulated diffraction pattern from 1,2-APB-β crystal structure (Figure 3). Therefore, 1,2-APB displays a temperature-induced crystal-to-crystal phase transition and only one new polymorph is obtained. Furthermore, the phase conversion between these two kinds of polymorphs is reversible. 1,2-APB-β can be changed back to 1,2-APB-α by dissolving in THF and then precipitating from the solution by solvent evaporation, which is verified by XRD analyses (Figure S2). Contrary to 1,2-APB, the XRD pattern of 1,3-APB heated powder is not entirely consistent with the simulated diffraction pattern from 1,3-APB-β crystal structure. As shown in Figure 4, the diffraction peaks at 2θ = 9.19, 14.32, and 18.85° (marked by asterisks) do not appear in the simulated XRD pattern. These diffraction peaks are also not entirely consistent with the XRD pattern of 1,3-APB-α. TLC test shows that 1,3-APB did not suffer from decomposition during heating. Therefore, another new polymorph (1,3-APB-γ) is possibly simultaneously produced with 1,3-APB-β phase. The XRD pattern of 1,3-APB sublimated crystals also displays similar situation, 9



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which further proves the existence of 1,3-APB-γ polymorph. As the sublimated crystals are all needle-like, we cannot discriminate between 1,3-APB-β and 1,3-APB-γ crystals by eyes. We have no choice but to measure the cell parameters of the sublimated crystals one by one in order to search 1,3-APB-γ. Very fortunately, 1,3-APB-γ crystal was successfully found without doing too much repetitive work and its structure was also solved. Now it can be clearly seen that the XRD pattern of the heated powder is the overlap of the simulated XRD patterns from 1,3-APB-β and 1,3-APB-γ polymorphs. The mixture of 1,3-APB-β and 1,3-APB-γ can also be reversibly converted to 1,3-APB-α by the same method as 1,2-APB (Figure S2). In all, substitution position exerts a remarkable effect on the polymorphism probability. With the two substituents varying from para-, ortho-, to meta-position, the polymorph number changes from 1, 2, to 3. 1,3-APB-β and 1,3-APB-γ are a pair of concomitant conformational polymorphs.24 Separating them is a great challenge. After carefully examining the XRD patterns, we noticed that the content of 1,3-APB-γ was possibly higher than that of 1,3-APB-β in the mixture for the strongest diffraction peak comes from 1,3-APB-γ. Efforts were then taken to separate these two concomitant polymorphs by sublimation. The heating temperature was increased a little, from 215 to 220 °C, so that slight sublimation can take place. The change of XRD patterns of the unsublimated powder on the evaporating boat was recorded with time. As shown in Figure S3, with increasing the heating time, the XRD peak intensity of 1,3-APB-β decreases gradually in comparison with that of 1,3-APB-γ. This implies that the content of 1,3-APB-β in the 10


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unsublimated powder decreases with the heating time. After about 85 hours, the diffraction peaks of 1,3-APB-β are totally disappeared. The residual on the evaporating boat are pure 1,3-APB-γ powder at least under the XRD detection limit, which was used in the following photophysical study. The sublimated crystals are still a mixture of 1,3-APB-β and 1,3-APB-γ.

Figure 5. (a) Molecular structure of 1,2-APB-β. (b) Stacking image of 1,2-APB-β molecules in the bc plane. (c) Stacking image in the spatial room. 1,2-APB-β crystallizes in the P212121 space group. Its molecule adopts a twisted structure and the two substituents are like the pincers of a crab (Figure 5a). The dihedral angle between anthryl ring and benzene ring is 85.55º. Due to the steric hindrance between the two arms at the ortho-position, the phenanthryl ring is not coplanar with the central benzene ring. The dihedral angle between them is 60.23º. As shown in Figure 5b, 1,2-APB molecules pack into a interlocked column structure in the bc plane. There are strong C-H···π interactions with the C-H···C distances of 2.823, 2.829, 2.864, and 2.874 Å. Within one column along the a-axis, the twisted molecules adopt a slipped face-to-face packing (Figure 5c). The centroid···centroid distance between adjacent anthracenes or phenanthrenes is 6.539 Å, which is too long 11



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to form effective π···π interaction. Though the shortest C···C distance between adjacent anthracene and phenanthrene is 3.396 Å, the π···π interaction would be very weak for they are arranged in a slipped mode and the centroid···centroid distance is as long as 6.361 Å.

Figure 6. (a) Stacking image of 1,3-APB-β molecules in the ac plane. (b) Stacking image in the spatial room. 1,3-APB-β crystallizes in the P21 space group. In comparison with 1,2-APB-β molecular configuration, the torsion degree of 1,3-APB-β molecule is drastically decreased due to the diminishing steric hindrance between the two arms at the meta-position. The dihedral angle between the anthryl ring and the benzene ring is 47.33º and the phenanthryl moiety is nearly coplanar with the central benzene ring with a small dihedral angle of 6.86º. For 1,3-APB-β molecule, the different torsion degrees of anthracene and phenanthrene with respect to benzene are attributed to the H···H steric hindrance between aromatic proton and vinylic proton. As for anthracene with a linear structure, its peripheral proton is repulsive to the adjacent vinyl proton to induce a high distortion. On the contrary, this repulsion is significantly diminished due to the non-linear structure of phenanthracene. As shown in Figure 6a, 1,3-APB-β 12


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molecules pack into a column structure along the b axis. Typical C-H···π interactions only exist between adjacent anthryls. Within one column, 1,3-APB-β molecules adopt a slipped face-to-face packing (Figure 6b). No obvious π···π interaction exists between adjacent anthracene rings for the centroid···centroid and the shortest C···C distances are 5.694 and 3.679 Å, respectively. In contrast, there are π···π interactions between adjacent parallel phenanthrylvinylbenzene moieties for the vertical and the shortest C···C distances are 3.507 and 3.407 Å, respectively.

Figure 7. (a) Stacking image of 1,3-APB-γ molecules in the bc plane. (b) Stacking image in the ac plane. 1,3-APB-γ crystallizes in the P212121 space group. In comparison with 1,3-APB-β, the dihedral angle between the anthryl ring and the benzene ring increases to 72.60º. However, the phenanthryl moiety is more coplanar with the benzene ring with a small dihedral angle of 1.60º. As shown in Figure 7a, 1,3-APB-γ molecules also pack into a column structure along the a axis. Though 1,3-APB-γ molecules along the c-axis adopt a similar packing as 1,3-APB-β molecules along the a-axis, the adjacent molecules are oppositely orientated. C-H···π interactions exist between adjacent anthryls or phenanthryls which adopt an edge-to-edge arrangement. Within one 13



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column, 1,3-APB-γ molecules also adopt a slipped face-to-face packing (Figure 7b). Similar

to

1,3-APB-β,

the

π···π

interaction

between

adjacent

phenanthrylvinylbenzene moieties is stronger than that between adjacent anthracene rings. The vertical and the shortest C···C distances between adjacent parallel phenanthrylvinylbenzene moieties are 3.451 and 3.465 Å, respectively. Solvatochromism. Though there is no typical electron donor or acceptor group in the molecular structure, it is unexpected that these three isomers all display solvatochromism. UV-vis absorption and emission spectra in different solvents are shown in Figure S4 and Figure 8, and the corresponding photophysical data are summarized in Table 1. Both the absorption and emission spectra display a bathochromic shift with increased solvent polarity, which indicates the existence of a solvatochromic effect. In comparison with the absorption spectra, the emission spectra display a stronger solvatochromic response to solvent polarity. This is due to the higher dipole moment in the excited state against the ground state, exhibiting a marked photoinduced intramolecular charge-transfer feature.40 The solvatochromic degree is closely related to substitution position. From hexane to DMSO, the emission maximum ranges from 486 to 507 nm for 1,2-APB, from 470 to 480 nm for 1,3-APB, and from 487 to 521 nm for 1,4-APB. Therefore, 1,4-APB displays the strongest solvatochromic effect. The solvatochromic degree is possibly determined by molecular conjugative effect.41 For the disubstituted benzene system, the conjugative effect only exists in the ortho- and para-substitution and the conjugation degree in ortho-position is smaller than that in para-position.33 Thus the π-conjugation degree 14


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increases from 1,3-APB, 1,2-APB, to 1,4-APB, which is consistent with the order of the solvatochromic degree. This conjugation degree also affects the optical properties of these three isomers in the same solvent. For instance, in CH2Cl2 solution, the first absorption maximum is 330 nm for 1,3-APB, 336 nm for 1,2-APB, and 351 nm for 1,4-APB, and the corresponding emission maximum is 480, 500, and 507 nm, respectively. Both the absorption and emission spectra display a bathochromic shift from 1,3-APB, 1,2-APB, to 1,4-APB.

Figure 8 Emission spectra of 1,2-APB (a) 1,3-APB (b) and 1,4-APB (c) in different solvents. λex = 388 nm. To elucidate the solvatochromic effect, density functional theory (DFT) calculations were carried out. Ground state molecule geometry was optimized via Gaussian 09 at the B3LYP/6-31G(d,p) level.42 The HOMOs and LUMOs are shown in Figure 9. The electron cloud is mainly localized over benzene and anthracene units. Thus anthracene has a strong electron-withdrawing ability against phenanthrene, which produces permanent dipole moment and results in the solvatochromism.40,43,44 As shown in Figure 9, the electron cloud of 1,4-APB partially extends to the phenanthrene unit and is distributed more evenly than that of 1,2-APB or 1,3-APB. This indicates a better conjugation degree, leading to the strongest solvatochromic 15



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effect of 1,4-APB.41

Figure 9. LUMO (upper) and HOMO (lower) orbitals of 1,2-APB (a), 1,3-APB (b), and 1,4-APB (c). Table 1. The absorption and emission properties of these three isomers in solution and solid state. Compound Medium

λabs (nm)

λem (nm)

τ(ns)a

ΦF

kF (s-1)b

knr (s-1)c

hexane

332, 385

486

0.53

5%

0.94×108

18.0×108

1,2-APB

8

CH2Cl2

336, 389

500

0.72

10%

1.4×10

8.6×108

DMSO

342, 390

507

1.30

20%

1.5×108

6.1×108

α phase

-d

476

0.68 (0.94)e

32%

3.6×108

7.7×108

31%

1.6×108

3.5×108

2.05 (0.06) β phase

-

476, 504

hexane

323, 385

470

2.83

44%

1.6×108

1.9×108

CH2Cl2

330 388

480

3.17

55%

1.7×108

1.4×108

DMSO

338, 389

480

3.50

90%

2.6×108

0.26×108

1.27 (0.51) 2.34 (0.49)

1,3-APB

8

α phase

-

505

8.12

47%

0.58×10

0.65×108

γ phase

-

483

1.01 (0.63)

25%

1.7×108

5.0×108

hexane

344, 387

487

2.69

4%

0.15×108

3.6×108

CH2Cl2

351, 390

507

0.30 (0.97)

4%

0.46×108

11.0×108

DMSO

356, 397

521

0.36 (0.98)

8%

1.2×108

13.6×108

14%

1.6×108

9.5×108

1.94 (0.37) 1,4-APB

2.70 (0.03)

2.63 (0.02) Solid

-

526

0.72 (0.94) 1.90 (0.06)

Excitation wavelength is 388 nm for all the fluorescence-related measurements.

a

The

corresponding emission maximum is set as the emission wavelength. b kF = ΦF/τ. c knr = 1/τ- kF. d not measured. e Fractional contribution.

Photophysical and AIEE properties. The solid emission spectra of these three 16


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isomers are also shown in Figure 8 and the data are listed in Table 1. The emission maximum is 476 nm for 1,2-APB-α, 505 nm for 1,3-APB-α, 483 nm for 1,3-APB-γ, and 526 nm for 1,4-APB solid. As for 1,2-APB-β, its emission spectrum is similar to that of 1,2-APB-α but with a broad character. The photoluminescence decay dynamics and quantum yields (ΦF) of these materials in solutions (hexane, CH2Cl2, and DMSO) and solid state were measured and the results are also shown in Table 1. The radiative (kF) and nonradiative (knr) rate constants were calculated based on quantum yield and average life time. For 1,2-APB and 1,3-APB, the solution decay behaviors are single-exponential and the lifetimes increase with increased solvent polarity from hexane, CH2Cl2, to DMSO. This is possibly due to the rearrangement of electronic excited states in different polar solvents.45 In comparison with 1,2-APB and 1,3-APB, the solution decay behaviors of 1,4-APB are much more complicated. In hexane solution, the photoluminescence decay fits a single-exponential manner. However, in CH2Cl2 and DMSO solutions, the excited molecules decay through two relaxation pathways, one with a long lifetime and the other with a short lifetime. These results indicate that there should be two kinds of emitting species in CH2Cl2 and DMSO solutions. The long-lived component would be the same as that in the hexane solution because the lifetimes are very similar. With increasing the solvent polarity from hexane to CH2Cl2 and DMSO, the amplitude of the long-lived component decreases drastically and the short-lived one becomes the major decay process. The emitting species with a short life is possibly a kind of specifically solvated conformer with a high dipole moment, something like 17



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the charge separated state in a typical D-π-A system. This species could be stable in polar solvent. The solid decay behaviors are all double-exponential except 1,3-APB-α.

The

photoluminescence

decay

of

1,3-APB-α

phase

fits

a

single-exponential manner and the lifetime is 8.12 ns, which is much longer than that of 1,3-APB-γ phase. As shown in Table 1, the substitution position exerts a remarkable effect on the solution emission efficiency. In the same solvent, 1,3-APB emits most efficiently, which is similar to the situations of bis[2-(9-anthracenyl)vinyl]benzene and (1-naphthyl)vinyl(9-anthryl)vinylbenzene position isomers.36,37 For example, in DMSO solution, the fluorescence quantum yield is 20% for 1,2-APB, 90% for 1,3-APB, and 8% for 1,4-APB. In comparison with ortho- and para-isomers, meta-substitution can increase the kF value and especially effectively decrease the knr value in solution (Table 1), which leads to the highest emission efficiency of 1,3-APB solution. Though the emission spectra of these three isomers all display positive solvatochromism, the solution fluorescence quantum yields increase with increased solvent polarity, showing a negative solvatokinetic effect.46 As for 1,2-APB and 1,3-APB, with increasing the solvent polarity, the kF values increase but the knr values decrease, which leads to the high quantum yields in the polar solvents. In contrast, both the kF and knr values of 1,4-APB increase in the polar solvents. For example, from hexane to CH2Cl2, the kF and knr values both increase by a factor of about three. This is possibly related to the change of the major emission decay process as discussed above. 18


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Figure 10. PL spectra of 1,2-APB (a), 1,3-APB (b), and 1,4-APB (c) in EtOH/water mixtures with different water volume fractions. The concentration is 1 × 10−5 M. As for 1,2-APB and 1,4-APB, the solid emission efficiency is higher than that of solution, indicating an AIEE behavior. This is further proved by a solvent-nonsolvent fluorescence test. Water was used as the nonsolvent. EtOH was used as the solvent. As shown in Figure 10, the fluorescence peak intensities are gradually intensified with the growing water fraction. The changes of emission peak intensity versus water volume fraction are presented in Figure S5. A dramatic enhancement of luminescence emission is observed when the water fraction is over 40% for 1,2-APB and 60% for 1,4-APB, which would be related to the aggregate formation.6,7 Therefore, both compounds 1,2-APB and 1,4-APB are AIEE-active. In comparison with 1,2-APB, the 19



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emission maximum of 1,4-APB display a red-shift upon increasing the water fraction. When compound 1,3-APB was done the same test, the emission is quenched at high water fractions (>50%), displaying an ACQ character. The initial increase in the emission intensity at low water fraction is attributed to the change of solvent polarity. By comparing the emission dynamics of the as-prepared powder with solution (Table 1), it could be concluded that the radiative process plays a major role in determining these different aggregation-induced emission behaviors. As for 1,2-APB and 1,4-APB, there is a marked enhancement in the kF values from solution to the as-prepared solid. Thus, the aggregate environment plays a beneficial role in the radiative process, which leads to an AIEE behavior. On the contrary, in comparison with its CH2Cl2 and DMSO solutions, the radiative process of as-prepared 1,3-APB powder is more effectively inhibited than the nonradiative process. This results in a drop in the emission efficiency.

CONCLUSION Three APB position isomers with ortho-, meta-, and para-substitutions were synthesized and compared. Though phrenanthrene is an isomer of anthracence, its electron-withdrawing ability is smaller than that of anthracence. When they connect to C=C double bond through 9-position, the repulsion degree between the vinylic proton and the peripheral proton at the aryl ring is different due to the different molecular shape of anthracene from phenanthrene. The substitution position can also affect both conjugative effect and intramolecular steric hindrance. These factors synergistically determine the crystal packings and photophysical properties of these three isomers. 20


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For 1,4-APB, there is no phase transition upon heating. In contrast, one new crystal phase for 1,2-APB and two new crystal phases for 1,3-APB were obtained. Their crystal structures were successfully determined. For 1,2-APB and 1,3-APB, crystal structure analyses show that the steric hindrance between the two substituents leads to different molecular conformation and packing pattern. Due to the strong electron-withdrawing ability of anthracene against phenanthrene, all isomers display solvatochromism. 1,4-APB displays the most remarkable solvatochromic effect due to its highest conjugation degree. The photoluminescence decay dynamics of 1,4-APB in the polar solvents fit a double-exponential manner, implying that two emitting species would coexist in the solution. Both compounds 1,2-APB and 1,4-APB display an AIEE behavior. Though 1,3-APB is quenched in the solid state, it shows the highest emission efficiency amongst these three isomers either in solution or in the solid state. The effect of the medium environment on the radiative process plays a vital role in determining their different aggregation-induced emission behaviours. This study would be helpful to understand the intriguing effects of the molecular configuration on the photophysical property and the polymorphism probability. The reversible transition between the different polymorphs may make them potential smart fluorescence materials.

EXPERIMENTAL SECTION Materials and Instrumentations. All chemicals were purchased from J&K Scientific

and

used

as

received

without

4-[(9-Anthryl)vinyl]benzyltriphenylphosphonium 21


further

purification. bromide,


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1-dimethoxyphosphorylmethyl-3-(9-anthryl)vinylbenzene,

Page 22 of 44

and

1-dimethoxyphosphorylmethyl-2-(9-anthryl)vinylbenzene were prepared according to the published procedures.37,47 1

H and

13

C NMR spectra were recorded on a Bruker Avance 400 spectrometer.

High-resolution mass spectral analyses were carried out on a Bruker maXis UHR-TOF mass spectrometer. Thermogravimetric (TG) and differential scanning calorimetry (DSC) analyses were measured on a METTLER TOLEDO TGA/DSC 1 instrument, in a flowing nitrogen atmosphere and with a 10 ºC min-1 to 600 ºC. Absorption measurements were carried out on a TU-1800 spectrophotometer. Absolute photoluminescence quantum yields (ΦF) were determined on an Edinburgh Instruments FLS920 using an integrating sphere. Photoluminescence measurements and time-resolved emission decay behaviours were recorded on an Edinburgh Instruments FLS920. The emission spectra were corrected for the instrumental spectral responses. For samples with a double-exponential decay behaviour, the average lifetime was used to calculate the radiative rate constant (kF) and nonradiative rate constant (knr). The average lifetime was calculated by the following equation:

< ߬ >=

‫ܤ‬ଵ ߬ଵଶ + ‫ܤ‬ଶ ߬ଶଶ ‫ܤ‬ଵ ߬ଵ + ‫ܤ‬ଶ ߬ଶ

where τ1 and τ2 are the lifetimes of the shorter- and longer-lived species, respectively, and B1 and B2 are their respective pre-exponential factor. X-ray diffraction investigations were carried out on a D8 Focus diffractometer equipped with Cu Kα radiation (λ = 1.5406 Å). Single-crystal X-ray diffraction measurements were conducted on an Oxford Diffraction Gemini E diffractometer. 22


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The structure was solved by direct method and refined by a full-matrix least-squares technique on F2 using SHELXL-97 programs.48,49 CCDC-1037059 (1,2-APB-β), 1037061 (1,3-APB-β), and 1037060 (1,3-APB-γ) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from the

Cambridge

Crystallographic

Data

Centre

via

www.ccdc.cam.ac.uk/data_request/cif. Synthesis. 1-(9-Anthryl)vinyl-2-(9-phenanthryl)vinylbenzene (1,2-APB). At room temperature, t-BuOK (0.16 g, 1.43 mmol) was added in batches into a mixture of 1-dimethoxyphosphorylmethyl-2-(9-anthryl)vinylbenzene (0.29 g, 0.72 mmol) and phenanthrene-9-carboxaldehyde (0.18 g, 0.87 mmol) in THF (20 mL) under nitrogen. After stirring overnight at room temperature, the mixture was poured into H2O (40 mL) and extracted by CH2Cl2. The organic phase was combined and dried over MgSO4. After evaporation of the solvent, the crude product was dried under vacuum and then recrystallized from ethyl acetate to afford a yellow solid (0.12 g, yield 34%). Mp: 234 °C. 1H NMR (CDCl3, 400 MHz) δ: 7.42-7.54 (m, 9H), 7.57-7.64 (m, 3H), 7.79-7.91 (m, 5H), 7.95-7.98 (m, 1H), 8.00-8.02 (m, 2H), 8.18 (d, J = 7.8 Hz, 1H), 8.41-8.45 (m, 3H), 8.61 (d, J = 8.2 Hz, 1H), 8.69 (d, J = 8.2 Hz, 1H). 13C NMR (CDCl3, 100.6 MHz) δ: 122.59, 123.22, 124.68, 124.73, 125.35, 125.76, 126.11, 126.64, 126.69, 126.73, 126.77, 126.87, 127.16, 127.21, 127.89, 128.27, 128.37, 128.86, 128.88, 129.45, 129.86, 129.88, 130.36, 130.53, 130.78, 131.64, 131.84, 133.00, 133.95, 135.84, 136.48. MS: m/z calcd for C38H27: 483.2035 [M+H]+; found: 483.2114. 23



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1-(9-Anthryl)vinyl-3-(9-phenanthryl)vinylbenzene (1,3-APB). This compound was prepared from t-BuOK (0.20 g, 1.78 mmol), phenanthrene-9-carboxaldehyde (0.22 g, 1.07 mmol), and 1-dimethoxyphosphorylmethyl-3-(9-anthryl)vinylbenzene (0.35 g, 0.87 mmol) in THF (20 mL) using the similar procedure described for 1,2-APB. The crude product was recrystallized from HCCl3 to afford a yellow solid (0.22 g, yield 52.4%). Mp: 231 °C. 1H NMR (CDCl3, 400 MHz) δ: 7.04 (d, J = 16.4 Hz, 1H), 7.33 (d, J = 16.0 Hz, 1H), 7.49-7.54 (m, 5H), 7.62-7.71 (m, 6H), 7.93-8.05 (m, 7H), 8.30-8.32 (m, 1H), 8.40-8.44 (m, 3H), 8.69 (d, J = 8.0 Hz, 1H), 8.75-8.78 (m, 1H). 13C NMR (CDCl3, 100.6 MHz) δ: 122.71, 123.31, 124.84, 125.25, 125.36, 125.51, 125.69, 126.12, 126.18, 126.44, 126.71, 126.75, 126.87, 126.99, 127.05, 128.88, 129.42, 129.92, 130.45, 130.62, 130.92, 131.68, 131.99, 132.07, 132.82, 134.05, 137.31, 137.98, 138.31. MS: m/z calcd for C38H27: 483.2035 [M+H]+; found: 483.2114. 1-(9-Anthryl)vinyl-4-(9-phenanthryl)vinylbenzene (1,4-APB). At room temperature, t-BuOK (0.18 g, 1.61 mmol) was added in batches into a mixture of 4-[(9-anthryl)vinyl]benzyltriphenylphosphonium bromide (0.50 g, 0.79 mmol) and phenanthrene-9-carboxaldehyde (0.18 g, 0.87 mmol) in CH2Cl2 (20 mL) under nitrogen. After stirring overnight at room temperature, the mixture was poured into H2O (40 mL) and extracted by CH2Cl2. The organic phase was combined and dried over MgSO4. After evaporation of the solvent, the crude product was chromatographed on silica gel (petroleum ether) to afford a yellow solid (0.11 g, yield 28.9%). Mp: 282 °C. 1H NMR (CDCl3, 400 MHz) δ: 7.01 (d, J = 16.4 Hz, 1H), 7.31 24


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(d, J = 16.0 Hz, 1H), 7.48-7.52 (m, 4H), 7.62-7.74 (m, 8H), 7.95-8.05 (m, 6H), 8.30-8.32 (m, 1H), 8.39-8.43 (m, 3H), 8.69 (d, J = 8.2 Hz, 1H), 8.76-8.79 (m, 1H). 13C NMR (CDCl3, 100.6 MHz) δ: 122.73, 123.35, 124.77, 125.11, 125.37, 125.69, 126.18, 126.57, 126.70, 126.77, 126.89, 127.02, 127.19, 127.37, 128.89, 129.94, 130.46, 130.67, 130.95, 131.71, 131.85, 132.03, 132.89, 134.07, 137.05, 137.10, 137.53. MS: m/z calcd for C38H27: 483.2035 [M+H]+; found: 483.2118.

ASSOCIATED CONTENT Supporting Information Synthetic routes, XRD patterns, absorption spectra in different solvents, emission peak intensities in EtOH-water mixtures with varying water volume fraction, thermal ellipsoid plot for the crystal structure, and X-ray crystal structural data. This material is available free of charge via the Internet at http://pubs.acs.org.

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

ACKNOWLEDGEMENTS This work was supported by the National Natural Science Foundation of China (21202061 and 21171069) and the Natural Science Foundation of Shandong Province of China (ZR2011EMQ007).

REFERENCES 25



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

Page 26 of 44

(1) Yoon, S.-J.; Chung, J. W.; Gierschner, J.; Kim, K. S.; Choi, M.-G.; Kim D.; Park, S.

Y.

Multistimuli

Two-Color

Luminescence

Switching

via

Different

Slip-Stacking of Highly Fluorescent Molecular Sheets. J. Am. Chem. Soc. 2010, 132, 13675-13683. (2) Chandrasekharan N.; Kelly, L. A. A Dual Fluorescence Temperature Sensor Based on Perylene/Exciplex Interconversion. J. Am. Chem. Soc. 2001, 123, 9898-9899. (3) Irie, M.; Fukaminato, T.; Sasaki, T.; Tamai N.; Kawai, T. A Digital Fluorescent Molecular Photoswitch. Nature 2002, 420, 759-760. (4) Farinola, G. M.; Ragni, R. Electroluminescent Materials for White Organic Light Emitting Diodes. Chem. Soc. Rev. 2011, 40, 3467-3482. (5) Usta, H.; Sheets, W. C.; Denti, M.; Generali, G.; Capelli, R.; Lu, S.; Yu, X.; Muccini M.; Facchetti, A. Perfluoroalkyl-Functionalized Thiazole-Thiophene Oligomers as N-Channel Semiconductors in Organic Field-Effect and Light-Emitting Transistors. Chem. Mater. 2014, 26, 6542-6556. (6) Luo, J.; Xie, Z.; Lam, J. W. Y.; Cheng, L.; Chen, H.; Qiu, C.; Kwok, H. S.; Zhan, X.;

Liu,

Y.;

Zhu,

D.;

et

al.

Aggregation-Induced

Emission

of

1-Methyl-1,2,3,4,5-pentaphenylsilole. Chem. Commun. 2001, 1740-1741. (7) An, B.-K.; Kwon, S.-K.; Jung, S.-D.; Park, S. Y. Enhanced Emission and its Switching in Fluorescent Organic Nanoparticles. J. Am. Chem. Soc. 2002, 124, 14410-14415. (8) Mei, J.; Hong, Y.; Lam, J. W. Y.; Qin, A.; Tang, Y.; Tang, B. Z. 26


Page 27 of 44

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


Aggregation-Induced Emission: The Whole Is More Brilliant than the Parts. Adv. Mater. 2014, 26, 5429-5479. (9) Shi, J.; Chang, N.; Li, C.; Mei, J.; Deng, C.; Luo, X.; Liu, Z.; Bo, Z.; Dong, Y.; Tang, B. Z. Locking the Phenyl Rings of Tetraphenylethene Step by Step: Understanding the Mechanism of Aggregation-Induced Emission. Chem. Commun. 2012, 48, 10675-10677. (10) Choi, S.; Bouffard, J.; Kim, Y. Aggregation-Induced Emission Enhancement of a Meso-Trifluoromethyl BODIPY via J-Aggregation. Chem. Sci. 2014, 5, 751-755. (11) Zhang, Y.; Liang, C.; Shang, H.; Ma, Y.; Jiang, S. Supramolecular Organogels and Nanowires Based on a V-Shaped Cyanostilbene Amide Derivative with Aggregation-Induced Emission (AIE) Properties J. Mater. Chem. C 2013, 1, 4472-4480. (12) Zhang, X.; Sørensen, J. K.; Fu, X.; Zhen, Y.; Zhao, G.; Jiang, L.; Dong, H.; Liu, J.; Shuai, Z.; Geng, H.; et al. Rubrene Analogues with the Aggregation-Induced Emission Enhancement Behaviour. J. Mater. Chem. C 2014, 2, 884-890. (13) Wang, H.; Liang, Y.; Xie, H.; Feng, L.; Lu, H.; Feng, S. Emission Enhancement and Color Adjustment of Silicon-Cored Structure in Tetraphenyl Benzene with Aggregation-Enhanced Emission. J. Mater. Chem. C 2014, 2, 5601-5606. (14) Zhang, G.-F.; Wang, H.; Aldred, M. P.; Chen, T.; Chen, Z.-Q.; Meng, X.; Zhu, M.-Q. General Synthetic Approach toward Geminal-Substituted Tetraarylethene Fluorophores with Tunable Emission Properties: X ‑ ray Crystallography, 27



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

Aggregation-Induced Emission and Piezofluorochromism. Chem. Mater. 2014, 26, 4433-4446. (15) Yang, Y.; Su, X.; Carroll, C. N.; Aprahamian, I. Aggregation-Induced Emission in BF2–Hydrazone (BODIHY) Complexes. Chem. Sci. 2012, 3, 610-613. (16) Zheng, Z.; Yu, Z.; Yang, M.; Jin, F.; Zhang, Q.; Zhou, H.; Wu, J.; Tian, Y. Substituent Group Variations Directing the Molecular Packing, Electronic Structure, and Aggregation-Induced Emission Property of Isophorone Derivatives. J. Org. Chem. 2013, 78, 3222-3234. (17) Chi, Z.; Zhang, X.; Xu, B.; Zhou, X.; Ma, C.; Zhang, Y.; Liu, S.; Xu, J. Recent Advances in Organic Mechanofluorochromic Materials. Chem. Soc. Rev. 2012, 41, 3878-3896. (18) Dong, Y.; Zhang, J.; Tan, X.; Wang, L.; Chen, J.; Li, B.; Ye, L.; Xu, B.; Zou, B.; Tian, W. Multi-Stimuli Responsive Fluorescence Switching: the Reversible Piezochromism and Protonation Effect of a Divinylanthracene Derivative. J. Mater. Chem. C 2013, 1, 7554-7559. (19) Qi, Q.; Liu, Y.; Fang, X.; Zhang, Y.; Chen, P.; Wang, Y.; Yang, B.; Xu, B.; Tian, W.; Zhang, S. X. AIE (AIEE) and Mechanofluorochromic Performances of TPE-methoxylates: Affects of Single Molecular conformations. RSC Adv. 2013, 3, 7996-8002. (20) Zhang, X.; Chi, Z.; Zhou, X.; Liu, S.; Zhang, Y.; Xu, J. Influence of Carbazolyl Groups on Properties of Piezofluorochromic Aggregation-Enhanced Emission Compounds Containing Distyrylanthracene. J. Phys. Chem. C 2012, 116, 28


Page 28 of 44

Page 29 of 44

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


23629-23638. (21) Dong, Y.; Xu, B.; Zhang, J.; Tan, X.; Wang, L.; Chen, J.; Lv, H.; Wen, S.; Li, B.; Ye, L.; et al. Piezochromic Luminescence Based on the Molecular Aggregation of 9,10-Bis((E)-2-(pyrid-2-yl)vinyl)anthracene. Angew. Chem. Int. Ed. 2012, 51, 10782-10785. (22) Gong, Y.; Tan, Y.; Liu, J.; Lu, P.; Feng, C.; Yuan, W. Z.; Lu, Y.; Sun, J. Z.; He, G.; Zhang, Y. Twisted D-π-A Solid Emitters: Efficient Emission and High Contrast Mechanochromism. Chem. Commun. 2013, 49, 4009-4011. (23) Luo, X.; Li, J.; Li, C.; Heng, L.; Dong, Y. Q.; Liu, Z.; Bo, Z.; Tang, B. Z. Reversible Switching of the Emission of Diphenyldibenzofulvenes by Thermal and Mechanical Stimuli. Adv. Mater. 2011, 23, 3261-3265. (24) Brog, J.-P.; Chanez, C.-L.; Crochet, A.; Fromm, K. M. Polymorphism, What It Is and How to Identify It: A Systematic Review. RSC Adv. 2013, 3, 16905-16931. (25) Bernstein, J. Polymorphism - A Perspective. Cryst. Growth Des. 2011, 11, 632-650. (26) Diao, Y.; Lenn, K. M.; Lee, W.; Blood-Forsythe, M. A.; Xu, J.; Mao, Y.; Kim, Y.; Reinspach, J. A.; Park, S.; Aspuru-Guzik, A.; et al. Understanding Polymorphism in Organic Semiconductor Thin Films Through Nanoconfinement. J. Am. Chem. Soc. 2014, 136, 17046-17057. (27) van der Poll, T. S.; Zhugayevych, A.; Chertkov, E.; Bakus, R. C. II; Coughlin, J. E.; Teat, S. J.; Bazan. G. C.; Tretiak, S. Polymorphism of Crystalline Molecular Donors for Solution-Processed Organic Photovoltaics. J. Phys. Chem. Lett. 2014, 29



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

Page 30 of 44

5, 2700-2704. (28) Zhang, H.; Zhang, Z.; Ye, K.; Zhang, J.; Wang, Y. Organic Crystals with Tunable Emission Colors Based on a Single Organic Molecule and Different Molecular Packing Structures. Adv. Mater. 2006, 18, 2369-2372. (29) Kumar, N. S. S.; Varghese, S.; Rath, N. P.; Das, S. Solid State Optical Properties of 4-Alkoxy-pyridine Butadiene Derivatives: Reversible Thermal Switching of Luminescence. J. Phys. Chem. C 2008, 112, 8429-8437. (30) Qi, Q.; Zhang, J.; Xu, B.; Li, B.; Zhang, S. X.; Tian, W. Mechanochromism and Polymorphism-Dependent

Emission

of

Tetrakis(4-(dimethylamino)phenyl)ethylene. J. Phys. Chem. C 2013, 117, 24997-25003. (31) Price, S. L. Predicting Crystal Structures of Organic Compounds. Chem. Soc. Rev. 2014, 43, 2098-2111. (32) Huang, J.; Sun, N.; Dong, Y.; Tang, R.; Lu, P.; Cai, P.; Li, Q.; Ma, D.; Qin, J.; Li, Z. Similar or Totally Different: The Control of Conjugation Degree through Minor Structural Modifi cations, and Deep-Blue Aggregation-Induced Emission Luminogens for Non-Doped OLEDs. Adv. Funct. Mater. 2013, 23, 2329-2337. (33) Samori, S.; Tojo, S.; Fujitsuka, M.; Ryhding, T.; Fix, A. G.; Armstrong, B. M.; Haley,

M.

M.;

Majima,

T.

Emission

from

Regioisomeric

Bis(phenylethynyl)benzenes during Pulse Radiolysis. J. Org. Chem. 2009, 74, 3776-3782. (34) Pascal, L.; Vanden Eynde, J. J.; Van Haverbeke, Y.; Dubois, P.; Michel, A.; Rant, 30


Page 31 of 44

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


U.; Zojer, E.; Leising, G.; Van Dorn, L. O.; Gruhn, N. E.; et al. Synthesis and Characterization of Novel para- and meta-Phenylenevinylene Derivatives: Fine Tuning of the Electronic and Optical Properties of Conjugated Materials. J. Phys. Chem. B 2002, 106, 6442-6450. (35) Winter, A.; Friebe, C.; Hager, M. D.; Schubert, U. S. Synthesis of Rigid π-Conjugated Mono-, Bis-, Tris-, and Tetrakis(terpyridine)s: Influence of the Degree and Pattern of Substitution on the Photophysical Properties. Eur. J. Org. Chem. 2009, 801-809. (36) Li, Y.; Chen, Z.; Cui, Y.; Xia, G.; Yang, X. Substitution Position Directing the Molecular Packing, Electronic Structure, and Aggregate Emission Property of Bis[2-(9-anthracenyl)vinyl]benzene System. J. Phys. Chem. C 2012, 116, 6401-6408. (37) Li, Y.; Pang, M.; Zhang, Z.; Li, G.; Sun, G. Substitution Position Tuning of the Different

Aggregation-Induced

Emission

Properties

of

Four

(1-Naphthyl)vinyl(9-anthryl)vinylbenzene Isomers: From ACQ to AIEE and AIE. RSC Adv. 2013, 3, 14950-14953. (38) He, J.; Xu, B.; Chen, F.; Xia, H.; Li, K.; Ye, L.; Tian, W. Aggregation-Induced Emission in the Crystals of 9,10-Distyrylanthracene Derivatives: The Essential Role of Restricted Intramolecular Torsion. J. Phys. Chem. C 2009, 113, 9892-9899. (39) Romero-Nieto, C.; Merino, S.; Rodríguez-López, J.; Baumgartner, T. Dendrimeric

Oligo(phenylenevinylene)-Extended 31



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

Dithieno[3,2-b:2',3'-d]phospholes-Synthesis,

Page 32 of 44

Self-Organization,

and

Optical

Properties. Chem. Eur. J. 2009, 15, 4135-4145. (40) Zhang, J.; Zhao, C.; Liu, H.; Lv, Y.; Liu, R.; Zhang, S.; Chen, H.; Zhang, G.; Tian, Z. Solvatochromic Fluorescence Emission of an Anthranol Derivative without Typical Donor-Acceptor Structure: An Experimental and Theoretical Study. J. Phys. Chem. C 2015, 119, 2761-2769. (41) Bonn,

A.

G.;

Wenger,

O.

Oligotriarylamine-Triarylborane

S.

Charge

Compounds.

J.

Transfer Org.

Emission

Chem.

2015,

in 80,

4097-4107. (42) 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.; et al. Gaussian 09, Revision A.01; Gaussian, Inc.: Wallingford CT, 2009. (43) Reichardt, C. Solvatochromic Dyes as Solvent Polarity Indicators. Chem. Rev. 1994, 94, 2319-2358. (44) Masternak,

A.; Wenska,

G.; Milecki,

J.; Skalski,

B.; Franzen,

S.

Solvatochromism of a Novel Betaine Dye Derived from Purine. J. Phys. Chem. A 2005, 109, 759-766. (45) Sahoo,

D.; Bhattacharya,

P.;

Chakravorti,

S.

Spectral

Signature

of

2-[4-(Dimethylamino)styryl]-1-methylquinolinium Iodide: A Case of Negative Solvatochromism in Water. J. Phys. Chem. B 2011, 115, 10983-10989. (46) Zhang, Z.; Xue, P.; Gong, P.; Zhang, G.; Peng, J.; Lu, R. Mechanofluorochromic Behaviors of Biminoenolate Boron Complexes Functionalized with Carbazole. J. 32


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Mater. Chem. C 2014, 2, 9543-9551. (47) Drefahl, G.; Plötner, G.; Winnefeld, K. Untersuchungen über Stilbene, XLII. [4-Vinyl-styryil]-Aromaten. Chem. Ber. 1961, 94, 2002-2010. (48) Sheldrick, G. M. A Short History of SHELX. Acta Cryst. A 2008, 64, 112-122. (49) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.; Puschmann, H. OLEX2: A Complete Structure Solution, Refinement and Analysis Program. J. Appl. Cryst. 2009, 42, 339-341.

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Molecular structure of three APB isomers 70x36mm (150 x 150 DPI)



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TG (a) and DSC (b) curves of compounds 1,2-APB, 1,3-APB, and 1,4-APB 71x110mm (300 x 300 DPI)


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XRD patterns of 1,2-APB polymorphs: (a) as-prepared powder (1,2-APB-α); (b) heating 1,2-APB-α at about 205 °C; (c) calculated from the crystal structure of sublimated crystals (1,2-APB-β) 60x35mm (300 x 300 DPI)



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XRD patterns of 1,3-APB polymorphs: (a) as-prepared powder (1,3-APB-α); (b) calculated from the crystal structure of sublimated crystals (1,3-APB-β); (c) heating 1,3-APB-α at about 215 °C; (d) crystals obtained via sublimation of 1,3-APB-α; (e) calculated from the crystal structure of 1,3-APB-γ 60x36mm (300 x 300 DPI)


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(a) Molecular structure of 1,2-APB-β. (b) Stacking image of 1,2-APB-β molecules in the bc plane. (c) Stacking image in the spatial room 119x52mm (300 x 300 DPI)



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(a) Stacking image of 1,3-APB-β molecules in the ac plane. (b) Stacking image in the spatial room 66x49mm (300 x 300 DPI)


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(a) Stacking image of 1,3-APB-γ molecules in the bc plane. (b) Stacking image in the ac plane 72x59mm (300 x 300 DPI)



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Emission spectra of 1,2-APB (a) 1,3-APB (b) and 1,4-APB (c) in different solvents. λex = 388 nm 150x40mm (300 x 300 DPI)


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LUMO (upper) and HOMO (lower) orbitals of 1,2-APB (a), 1,3-APB (b), and 1,4-APB (c) 93x42mm (300 x 300 DPI)



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PL spectra of 1,2-APB (a), 1,3-APB (b), and 1,4-APB (c) in EtOH/water mixtures with different water volume fractions. The concentration is 1 × 10−5 M 51x121mm (300 x 300 DPI)


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(9-Anthryl)vinyl(9-phenanthryl)vinylbenzene Position Isomers

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