Aggregation-induced emission and the working mechanism of 1-benzoyl and 1-benzyl pyrene derivatives

Article abstract of DOI:10.1039/c8cp00260f

Over the past decade, research studies on solid-state luminescent materials featuring aggregation-induced emission (AIE) have achieved great success. It has been proved that lots of planar ACQ (aggregation-caused quenching) chromophores can be converted t

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Aggregation-induced emission and working mechanism of 1-
benzoyl and 1-benzyl pyrene derivatives
Yingying Zhang,a† Bairong He,a† Junkai Liu,a Shimin Hu,a Lingxiang Pan,a Zujin Zhao,*a and Ben
Zhong Tang*a,b
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Over the past decade, the researches on solid-state luminescent materials featuring aggregation-induced emission (AIE)
have achieved great success. It has been proved that lots of planar ACQ (aggregation-caused quenching) chromophores
can be turned to AIE luminogens (AIEgens) by combination of other AIE-active unit such as tetraphenylethene (TPE). In this
work, we present a new method to create AIE luminogens just by introducing benzoyl or benzyl to a planar chromophore,
pyrene. The generated 1-benzoyl and 1-benzyl pyrene derivatives exhibit weak emission when molecularly dissolved in
good solvents but strong emission from pyrene dimers when aggregated in poor solvent or solid state. The crystal
structure analysis and theoretical calculation are performed to depict the working mechanism of these new AIEgens. The
results show that the structural rigidification of these 1-benzoyl pyrene derivatives is the major cause for their AIE effect.
This new AIE system along with clear working mechanism will contribute to the development of AIE-related functional
materials and theory.
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However, it is subjected to self-aggregation and fluorescence
quenching,6 and highly efficient solid-state emitters based on
pyrene are much desired. Actually, researches have shown
Introduction
Traditional fluorescent materials may experience weakened
emission in the aggregated state due to the formation of
detrimental species. This phenomenon is commonly referred
to aggregation-caused quenching (ACQ).1 However, strong
emission in the aggregated state plays a vital role in practical
applications, such as organic light-emitting diode (OLED),2
bioimaging,3 optical waveguide,4 and so on. Obviously, most
ACQ materials can’t meet the demand, although various
chemical, physical and engineering approaches may alleviate
the ACQ effect to some extent. On the contrary, aggregation-
induced emission (AIE) materials are weakly fluorescent or
non-fluorescent in solutions, but show greatly enhanced
emission in the aggregated state, opening a new path to
solving the ACQ problem and developing highly efficient solid-
state luminescent materials.5
that the ACQ property of pyrene is not immutable in some
cases. With the aid of certain molecular structure modulation
or utilization of excimer emission, pyrene derivatives can be
successfully utilized in optical sensors,7 field effect transistors,8
OLEDs,9 etc. Particularly, introducing AIE unit to ACQ
chromophores has been proved as a powerful strategy to
create efficient solid-state emitters.5d-h For example, by
grafting AIE-active tetraphenylethene (TPE) onto the
peripheries of pyrene, the generated pyrene derivatives are
typical AIE luminogens (AIEgens), and have been applied to
fabricate highly efficient OLED devices.9c Other AIE-active
pyrene derivatives are also emerging in recent years.10 And the
enhanced emission may result from suppression of
intramolecular rotation, photoinduced electron transfer (PET),
charge transfer (CT), or even certain excimer species. Even so,
AIE-active pyrene systems are still very limited, leaving much
space for further improvements of functional materials based
on pyrene and deeper investigations on AIE mechanisms. In
this work, we report a new series of AIE-active 1-benzoyl and1-
benzyl pyrene derivatives, which were readily prepared by
Friedel-Crafts reactions, and their photophysical properties
had been systematically studied. Single crystal and theoretical
analyses were also conducted to understand the working
mechanism of emission enhancement in the aggregated state
in comparison with the solution state.
Pyrene is a popular traditional chromophore with a big,
planar π‒conjugated system with intriguing merits, such as
long fluorescence lifetime and pure blue fluorescence.
a Center for Aggregation-Induced Emission, State Key Laboratory of Luminescent
Materials and Devices, South China University of Technology, Guangzhou 510640,
China. Email: mszjzhao@scut.edu.cn.
b Department of Chemistry, Hong Kong Branch of Chinese National Engineering
Research Center for Tissue Restoration and Reconstruction, The Hong Kong
University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China.
Email: tangbenz@ust.hk.
† Both authors contributed equally to this work.
Electronic Supplementary Information (ESI) available: Synthetic routes; PL spectra
in THF/water mixtures with different water fractions; transient PL decay curves; PL
spectra in films and crystal, molecular packing manners in crystals; PL spectra of
compound 6 in different solvents; HRMS and NMR spectra.
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Scheme 1. Chemical structures of compounds 1–8.
results were in good agreement with their structures (the
detailed characterization data are given in the Experimental
section and the raw spectra are supplied in ESI). All the 1-
benzoyl and 1-benzyl pyrene derivatives were soluble in
common organic solvents, including THF, chloroform,
dichloromethane, etc., but almost insoluble in water.
Results and discussion
Synthesis
The molecular structures of the new 1-benzoyl and 1-benzyl
pyrene derivatives are illustrated in Scheme 1, and their
synthetic routes are shown in Scheme S1 in the Electronic
Supplementary Information (ESI). In brief, the Friedel-Crafts
acylation reactions of pyrene with corresponding acyl chloride
Optical property
The absorption spectra of 1-benzoyl and 1-benzyl pyrene
derivatives in THF solutions (10-5 M) are shown in Fig. 1.
Compounds
maximum absorptions locating at 385
However, compound shown a greatly red-shifted absorption
1
–
6
exhibited similar spectral profiles along with
compounds generated desired 1-benzoyl pyrene derivatives (
and ) in moderate yields of 46 78% at room
temperature. Compound , which was used as a control, was
1,
–
395 nm (Table 1).
2,
4,
6
7
–
7
8
maximum at 409 nm, which was owing to the strong electron-
withdrawing effect of perfluorophenyl group, and thus strong
obtained by Friedel-Crafts alkylation reaction of pyrene with
benzyl bromide with a lower yield of 36%, even if at 80 oC for 4
intramolecular charge transfer (ICT) effect. As for compound 8,
hours. The Suzuki-Miyaura couplings of
1 and 4 with
the maximum absorption peak was apparently blue-shifted to
339 nm, due to its poor conjugation in the presence of sp3
hybridization carbon linkage between pyrene and benzene.
The photoluminescence (PL) properties of the 1-benzoyl and
1-benzyl pyrene derivatives in different states were fully
phenylboronic acid furnished 3 and 5, respectively. These 1-
benzoyl and 1-benzyl pyrene derivatives had been fully
characterized by NMR and mass spectroscopies, and the
1.0
studied. As shown in Table 1 and Fig. S1, compounds
1‒6
1
3
5
7
2
4
6
8
exhibited weak blue PL emissions in the range of 428‒447 nm
in THF solution, with low fluorescence quantum yields (ФFs) of
0.2‒0.6%, disclosing that they were weak emitters in the
0.8
0.6
0.4
0.2
0.0
solution state. Compound
7 exhibited stronger PL emission
peaking at 434 nm and a higher ФF of 9.3%. Compound
8,
however, had a bluest PL emission at 395 nm with a ФF of 2.9%,
due to the weakest molecular conjugation. These emissions
were associated with the single-molecule state of these
compound in dilute solution. In the aggregated state, these 1-
benzoyl and 1-benzyl pyrene derivatives showed enhanced
and red-shifted emissions. By adding a large amount of water
into the THF solution, the nearly nonfluorescent compound
1
showed clearly increased emission with a red-shifted peak (Fig.
2A). Similar emission behaviors could also be observed for
250
300
350
400
450
Wavelength (nm)
compounds 2–8. As a matter of fact, the addition of water
Fig. 1 Absorption spectra of the new 1-benzoyl and 1-benzyl
pyrene derivatives in THF solutions (10-5 M).
should have resulted in aggregate formation because of their
inherent hydrophobicity characteristics of the compounds,
2 | J. Name., 2012, 00, 1-3
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80
fw (vol%)
C
fw
(
vol%
)
B
A
1
2
3
4
5
6
99
90
80
70
60
50
40
30
20
10
0
99
90
80
70
60
50
40
30
20
10
0
60
0
80 99
7
40
20
0
0
99
410
460
510
560
610
660
710
0
20
40
60
80
100
360
410
460
510
560
610
fw (vol%)
Wavelength (nm)
Wavelength (nm)
Fig. 2 PL spectra of (A) 1 and (C) 8 in THF/water mixtures with different water fractions; (B) Plots of the relative PL intensity (I/I0) versus fw
for 1, 2, 3, 4, 5, 6 and 7. I0 = intensity in pure THF. Inset: Fluorescence photos taken under a UV lamp (365 nm).
thus the enhanced and red-shifted emissions came from the between neighbouring pyrene rings in the ground state, that is
aggregates, demonstrating the AIE characteristics.
As shown in Fig. S1 and Table 1, the emissions of aggregates benzyl pyrene derivatives. The apparently higher emission
in THF/H2O mixtures with a water fraction of 99% and films of efficiencies and longer lifetimes of compound in the
compounds 7, as well as crystals of compounds , and aggregated state than compounds should be attributed to
to say, dimer-emission took place in these 1-benzoyl and 1-
8
1
‒
1,
2
4
‒7
1‒7
were obviously red-shifted in comparison with those in the absence of carbonyl group, which could lead to vibrational
solutions. And the corresponding peak emission wavelengths motion, strong dipole-dipole interaction, fluorescence-
were 498‒544, 449‒525, and 462‒553 nm for the aggregates, quenching n–π* transition and intersystem crossing (ISC)
films and crystals, respectively. The ФFs of the aggregates for process, and thus accelerate nonradiative decay of the excited
compounds
1‒7
were higher (1.7‒12.8%) than those of state.11
solutions, and could be further enhanced to 4.7‒36.1% in films,
suggesting that these 1-benzoyl pyrene derivatives were new
Single crystal structure
AIEgens indeed. It is worth mentioning that compound
showed stronger emission than compounds , no matter in
aggregates or films. Compound
7
1‒6
It has been well known that solid-state emission is closely
8
possessed even higher ФFs in associated with the packing arrangement of the luminogen.11,12 We
aggregates and films (42.5% and 55.4%, respectively) than obtained single crystals of compounds 1, 2, and 4‒7 and used them
those of 1-benzoyl pyrene derivatives, which was consistent to further study and understand the emission behaviors of these 1-
with the tendency of their fluorescence lifetimes (Table 1). benzoyl pyrene derivatives. The single crystals were grown from
Furthermore, the large red-shifts in the excitation spectra dichloromethane/n-hexane mixtures, and analyzed by X-ray
compared to absorption spectra (Fig. S2) indicated interactions diffraction crystallography. The crystal structures and the
Table 1. Optical properties of new pyrene derivatives.
λem (nm)
ФF (%)
aggrb
‹τ› (ns)
aggrb
λabs
solna
aggrb
filmc
crytd
solna
filmc
crytd
solna
filmc
crytd
(nm)
1
2
3
4
5
6
7
8
395
395
391
388
386
385
409
339
428
447
428
437
434
430
434
395
520
518
513
505
498
509
544
478
517
509
502
481
449
500
525
470
540
553
-
0.5
0.4
0.6
0.3
0.2
0.4
9.3
2.9
6.7
1.7
8.1
5.0
11.8
3.0
-
1.5
0.3
1.6
0.4
0.9
1.4
0.4
19.3
9.7
3.1
15.4
2.9
19.7
3.5
-
4.0
6.2
10.7
7.8
10.1
3.1
483
462
509
543
-
8.2
13.9
4.7
13.4
2.8
4.6
43.2
-
1.6
0.6
2.2
4.0
-
2.3
5.3
5.2
2.0
6.1
3.1
0.4
12.8
42.5
36.1
55.4
16.1
43.3
19.4
38.4
a THF solution (10-5 M); b THF/H2O mixed solution (fW = 99%); c Drop-casted on a quartz plate; d Single crystal. The fluorescence quantum
yield (ФF) was measured by a calibrated integrating sphere.
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corresponding dihedral angles (θ) between the pyrene and benzene S6). And the shortest C–C distances between the two neighboring
rings linked to the carbonyl group are illustrated in Table S1. In pyrene rings were 3.545 and 3.554 Å for compounds 1 and 2,
compounds 1 and 2, the θ values were 87.1o and 86.0o, respectively, respectively, indicative of typical intermolecular π‒π stacking
revealing the almost perpendicular bonding manners of the pyrene interactions. Similar anti-parallel slipped packing patterns and π‒π
and benzene rings, and thus the highly twisted structures. The
θ
interactions for pyrene dimers could be observed in compounds 4
values of compounds 1 and 2 were much bigger than those of and 6 (Table S1). In addition, pyrene dimerization could be affected
compounds 4 (62.2o), 5 (68.6o), 6 (66.3o), and 7 (66.0o), which by certain substituents. That is to say, in compound 7, the
might be attributed to the stronger steric hindrance of 2-positioned perfluoro-substitution altered the parallel stacking manner to an
substitution. On the whole, certain free rotation of the rings could edge-to-face one. In addition, the anti-parallel packing manner was
lead to fluorescence quenching in solutions to some extent.
changed to a parallel one for compound 5, in which the biphenyl
Moreover, the molecular packing models and intermolecular units interacted through typical C–H···π interactions (Fig. 3d). It is
interactions were investigated to further understand the emission worthy of mentioning that, for compound 7, stacked pyrene pairs
properties of the aggregates (Fig. 3, Fig. S5‒S10). As shown in Fig. 3, were more likely to be a 3D network stacking, unlike 2D ones of
various intermolecular interactions could be clearly found in all the others, and it became more apparent as observed from the c-axis
crystals, including π‒π, C–H···π, C–X···π (X denotes halogen atoms), (Fig. S10), deducing that molecular motions were restricted more
C–H···O, C‒H···X interactions, and even H-/F-bonding interactions, effectively in compound
7 than in other 1-benzoyl pyrene
which were undoubtedly conducive to rigidifying molecular derivatives. And this explained why compound 7 possessed the
structures and restraining non-radiative dissipations in the highest ФF among 1-benzoyl pyrene derivatives. In a word, π-
aggregated state, rendering enhanced emission in aggregates. overlapped pyrene pairs existed and contributed to the dimer
Meanwhile, diversities exist when having a thorough look at them. emission in all the 1-benzoyl pyrene derivatives. All of the weak
Both compounds 1 and 2 had anti-parallel-packed and partially intermolecular interactions were beneficial to rigidifying the
overlapped dimeric pyrene pairs (Table S1), and the dimeric pairs molecular packing systems, suppressing the nonradiative relaxation,
13
. Besides,
turned to be 2D herringbone-like packing arrangements (Fig. S5 and and thus resulting in solid-state emission enhancement
Fig. 3 Packing patterns and intermolecular interactions of (a) 1, (b) 2, (c) 4, (d) 5, (e) 6 and (f) 7 in crystals.
4 | J. Name., 2012, 00, 1-3
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Fig. 6 Reorganization energy ratios of bound length, bound
angle and dihedral angle in gas and solid phases for
compound 6.
Fig. 4 Calculated molecular orbital amplitude plots of HOMOs
and LUMOs of compound 6 in gas and solid phases.
the 3D arrangement seemed to be more effective to enhance the
emission than 2D arrangement.
Electronic structure
Fig. 7 Optimized overlapped S0 and S1 geometric structures of
compound in gas and solid phases. Color codes for
In order to better understand the enhanced emission in the
aggregated state of 1-benzoyl pyrene derivatives, theoretical
6
structures：S1, red carbonyl oxygen and cyan hydrogen; S0, yellow
calculation was conducted on compound
6 as an example. carbonyl oxygen and purple hydrogen.
Considering the aggregation effect, we also calculated the
geometric and electronic structures of a large cluster cut from
depends on the competition between the radiative and
nonradiative decays. In other words, if the excited molecules
return to the ground state in a dominative radiation transition,
they fluoresce. For these AIE-active luminogens, their radiative
and nonradiative reorganization energies were calculated and
compared to have a thorough understanding of the emission
behaviors in gas and solid phases. Fig. 5 shows the calculated
the crystal structure by using
a combined quantum
mechanics/molecular-mechanics (QM/MM) approach.14 The
QM part chose the Turbomole 6.5 quantum chemistry package,
and the MM part chose the DL-POLY molecular mechanics
package. For compound 6, the ground state and excited states
configurations in both gas and solid states were optimized by
density functional theory (DFT) and time dependent density
functional theory (TDDFT), respectively. As shown in Fig. 4, the
reorganization energies of compound
6 in gas and solid phases,
and the reorganization energy ratios of bond length, bond
angle and dihedral angle are illustrated in Fig. 6. It can be seen
that the high frequency bond stretching and bond angle open-
close motions consumed large amounts of reorganization
energy in both gas and solid phases, with proportions up to
64% and 78%, respectively. In solution, intramolecular bond
stretching, angle changing and rotation dissipated most of the
excited-state energy, and led to faint emission. While in solid
state, the low frequency dihedral angle variation could be
restricted by physical constraint, resulting in emission
enhancement. These results further validated that restriction
electron clouds of HOMO and LUMO of compound
6 were
mainly centered on the pyrene and benzene units, respectively,
in gas and solid phases. The carbonyl group contributed to
both HOMO and LUMO. The separated distribution of HOMO
and LUMO and twisted geometrical structure revealed that
compound
been further confirmed by solvatochromic effect studies.
Obvious PL variations of compound in nonpolar and high-
6 would readily experience ICT effect, which had
6
polar solvents could be observed (Fig. S11), and the emission
peak in toluene was 414 nm and moved to 463 nm in DMSO.
Generally, whether an excited fluorescent molecule emits
of intramolecular motion (RIM)5b,15
accounted for the
emission enhancement in the aggregated state. Another thing
to be mentioned is that, the high frequency bond stretching
and bond angle open-close motions were the intrinsic
characteristics, and relatively difficult to be confined by
intermolecular stacking. This is one of the reasons why the PL
1200
1000
800
600
400
200
0
1200
1000
800
600
400
200
0
Gas
Solid
efficiency of compound
the aggregated state.
6 is lower than that of compound 8 in
In order to gain deeper insight into the conformational
changes from S0 (gas) to S1 (solid) state, the overlap of their
geometries was also studied. As illustrated in Fig. 7, the S1 and
0
500 1000 1500 2000 2500 3000 3500
0
500 1000 1500 2000 2500 3000 3500
Normal mode wavenumber (cm-1
)
Normal mode wavenumber (cm-1
)
S0 geometries of compound
6 were almost perfectly
overlapped in solid phase, demonstrating negligible
conformation variations in the excited state. But it was not the
Fig. 5 The calculated reorganization energies versus the normal
mode wavenumber for compound in gas and solid phases.
6
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case in gas phase, namely, the S1 geometry distinctively (TMS, ppm): 198.4, 144.7, 139.1, 133.6, 130.5, 130.3, 130.0, 129.6,
changed compared with the S0 geometry, in terms of 129.2, 129.1, 128.94, 128.89, 128.8, 126.9, 126.2, 125.6, 125.5,
conformational twisting and rotation. These changes 125.4, 124.10, 124.06, 123.2, 122.8. HRMS (C23H13IO): m/z 432.0040
undoubtedly consumed much excited state energy, and thus ([M+], calcd 432.0011).
caused weak solution-state emission. In a word, the larger [1,1'-Biphenyl]-2-yl(pyren-1-yl)methanone (3): A mixture of 1 (1.54
changes of S1 geometry in gas phase than those in solid phase g, 4 mmol), phenylboronic acid (0.59 g, 4.8 mmol), Pd(PPh3)4 (0.23 g,
gave rise to weak emission in solutions, while the minimized 0.20 mmol) and K2CO3 (2.21 g, 16 mmol) in toluene/ethanol/water
changes of S1 geometry in solid phase accounted for the (100 mL, 8/1/1 v/v/v) were heated to reflux for 12 h under nitrogen.
enhanced emission.
After cooling to room temperature, the reaction mixture was
poured into water, and extracted with dichloromethane for three
times. The combined organic layers were dried over anhydrous
Conclusion
magnesium sulfate. After filtration and solvent evaporation, the
In conclusion,
a
series of 1-benzoyl and 1-benzyl pyrene residue was purified by silica-gel column chromatography using
derivatives were readily synthesized and characterized. They were petroleumether/dichloromethane as the eluent. Light yellow
weak emitters with monomer emission of pyrene moiety in powder, yield 64%. 1H NMR (500 MHz, CDCl3), δ (TMS, ppm): 8.91 (d,
solutions, but showed apparently enhanced emissions with J = 9.30 Hz, 1H), 8.23−8.16 (m, 3H), 8.08 (d, J = 8.90 Hz, 1H),
contributions from dimer emission of pyrene moieties in the 8.03−8.00 (m, 1H), 7.92 (d, J = 9.00 Hz, 1H), 7.87 (s, 2H), 7.75 (d, J =
aggregated state. Crystal analyses of 1-benzoyl pyrene derivatives 7.55 Hz, 1H), 7.63−7.60 (m, 1H), 7.52−7.46 (m, 2H), 7.24−7.22 (m,
revealed that they had highly twisted molecular conformations, and 2H), 6.92−6.89 (m, 2H), 6.76−6.73 (m, 1H). 13C NMR (125 MHz,
various intermolecular interactions were formed among molecules, CDCl3), δ (TMS, ppm): 200.6, 142.1, 140.9, 140.2, 133.7, 132.3,
which was conducive to molecular structure rigidification and thus 130.9, 130.8, 130.5, 130.48, 130.40, 130.3, 130.0, 129.4, 129.3,
emission enhancement in the aggregated states. Theoretical 128.9, 128.7, 127.8, 127.2, 127.0, 126.8, 126.2, 126.1, 126.0, 125.0,
calculation results showed that the inhibited intramolecular 124.6, 124.1, 123.3. HRMS (C29H18O): m/z 382.1384 ([M+], calcd
motions, along with smaller S1 geometric changes of aggregates 382.1358).
resulted in enhanced emission in the aggregated state. This (4-Bromophenyl)(pyren-1-yl)methanone (4): The synthesis was
instructive work had surely provided an effective and feasible way analogous to that described for compound 1. Yellow powder, yield
1
for turning the ACQ materials to AIE ones, and further validated the 64%. H NMR (500 MHz, CDCl3), δ (TMS, ppm): 8.32 (d, J = 9.25 Hz,
RIM mechanism of AIE.
1H), 8.28−8.24 (m, 2H), 8.21−8.19 (m, 2H), 8.13−8.11 (m, 2H),
8.08−8.04 (m, 2H), 7.77−7.74 (m, 2H), 7.63−7.60 (m, 2H). 13C NMR
(125 MHz, CDCl3), δ (TMS, ppm): 196.3, 136.5, 132.3, 131.4, 131.0,
130.8, 130.1, 129.6, 128.7, 128.3, 128.1, 127.4, 126.2, 125.9, 125.5,
125.2, 125.0, 123.8, 123.5, 123.4, 122.8. HRMS (C23H13BrO): m/z
384.0182 ([M+], calcd 384.0150).
Experimental
Synthesis and characterization
[1,1'-Biphenyl]-4-yl(pyren-1-yl)methanone (5): The synthesis was
analogous to that described for compound 3. Yellow powder, yield
(2-Bromophenyl)(pyren-1-yl)methanone (1): Anhydrous AlCl3 (2.67
g, 20 mmol), 2-bromobenzoyl chloride (1.57 mL, 12 mmol) and
pyrene (2.02 g, 10 mmol) were dissolved in 80 mL dry
dichloromethane at 0 oC. After stirring for 3 hours at room
temperature, the reaction mixture was poured into dilute
hydrochloric acid solution and extracted with dichloromethane for
three times. The combined organic layers were dried over
anhydrous magnesium sulfate. After filtration and solvent
evaporation, the residue was purified by silica-gel column
chromatography using petroleum/dichloromethane as the eluent.
1
68%. H NMR (500 MHz, CDCl3), δ (TMS, ppm): 8.36 (d, J = 9.25 Hz,
1H), 8.26−8.17 (m, 4H), 8.13−8.10 (m,3H), 8.07−8.04 (m, 1H),
7.97−7.95 (m, 2H), 7.70−7.68 (m, 2H), 7.65−7.64 (m, 2H), 7.48−7.45
(m, 2H ), 7.42−7.38 (m, 1H). 13C NMR (125 MHz, CDCl3), δ (TMS,
ppm): 198.0, 145.9, 139.9, 137.4, 133.3, 133.0, 131.24, 131.2, 130.7,
129.7, 129.1, 129.0, 128.9, 128.3, 127.3, 127.2, 127.3, 126.9, 126.4,
126.1, 125.9, 124.84, 124.78, 124.5, 123.8. HRMS (C29H18O): m/z
382.1319 ([M+], calcd 382.1358).
Phenyl(pyren-1-yl)methanone (6): The synthesis was analogous to
that described for compound 1. Yellow powder, yield 78%. 1H NMR
(500 MHz, CDCl3), δ (TMS, ppm): 8.35 (d, J = 7.25 Hz, 1H), 8.26−8.17
(m, 4H), 8.12−8.03 (m, 4H), 7.90−7.89 (m, 2H), 7.63−7.59 (m, 7.95
Hz, 1H), 7.49−7.46 (m, 2H). 13C NMR (125 MHz, CDCl3), δ (TMS,
ppm): 197.4, 137.7, 132.14, 132.10, 132.0, 130.1, 129.65, 129.58,
128.7, 128.1, 127.8, 127.4, 126.2, 125.9, 125.4, 125.0, 124.9, 123.8,
123.7, 123.4, 122.7. HRMS (C23H14O): m/z 329.0935 ([M+ + Na],
calcd 329.0937).
1
The yellow solid of compound 1 was obtained in 62% yield. H NMR
(500 MHz, CDCl3), δ (TMS, ppm): 9.17 (d, J = 9.35 Hz, 1H), 8.26−8.20
(m, 3H), 8.13 (d, J = 8.85 Hz, 1H), 8.04−7.96 (m, 4H), 7.66−7.64 (m,
1H), 7.53−7.52 (m, 1H), 7.43−7.40 (m, 1H), 7.37−7.34 (m, 1H). 13C
NMR (125 MHz, CDCl3), δ (TMS, ppm): 197.1, 141.4, 133.6, 132.5,
130.5, 130.0, 129.9, 129.6, 129.4, 129.22, 129.17, 129.13, 128.7,
126.3, 126.2, 125.6, 125.5, 125.4, 124.05, 123.97, 123.2, 122.8,
119.4. HRMS (C23H13BrO): m/z 384.0156 ([M+], calcd 384.0150).
(2-Iodophenyl)(pyren-1-yl)methanone (2): The synthesis was
analogous to that described for compound 1. Yellow powder, yield
46%. 1H NMR (500 MHz, CDCl3), δ (TMS, ppm): 9.17 (d, J = 9.35 Hz,
2H), 8.31−8.27 (m, 3H), 8.21 (d, J = 8.90 Hz, 1H), 8.10−8.06 (m, 3H),
7.99−7.97 (m, 2H), 7.50−7.46 (m, 2H). 13C NMR (125 MHz, CDCl3), δ
(Perfluorophenyl)(pyren-1-yl)methanone (7): The synthesis was
analogous to that described for compound 1. Orange powder, yield
1
72%. H NMR (500 MHz, CDCl3), δ (TMS, ppm): 9.40 (d, J = 9.35 Hz,
1H), 8.39−8.32 (m, 3H), 8.27 (d, J = 8.90 Hz, 1H), 8.16−8.09 (m, 4H).
13C NMR (125 MHz, CDCl3), δ (TMS, ppm): 185.8, 134.8, 130.4, 130.2,
6 | J. Name., 2012, 00, 1-3
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ARTICLE
130.1, 129.9, 129.5, 129.0, 127.6, 126.4, 126.1, 126.0, 125.8, 124.0, Crystal data for 7 (CCDC 1533090): C23H9F5O, MW = 396.30,
123.4, 123.1, 122.9. HRMS (C23H9F5O): m/z 396.0612 ([M+], calcd orthorhombic, P2(1)2(1)2(1), a = 7.9511(5), b = 8.4125(7), c =
396.0574).
24.0545(18) Å, V = 1609.0(2) Å3, Z = 4, Dc = 1.636 g cm-3, μ = 0.139
1-Benzylpyrene (8): Anhydrous AlCl3 (2.67 g, 20 mmol) and benzyl mm-1 (MoKα, λ = 0.71073), F (000) = 800.0, T = 173 K, 2θmax = 25.350
bromide (2.40 mL, 20 mmol) were added to pyrene (2.02 g, 10 (99.0%)o, 2903 measured reflections, 2157 independent reflections
mmol) dissolved in 80 mL dry dichloromethane at 0 oC. The reaction (Rint = 0.0530), GOF on F2 = 1.065, R1 = 0.0878, wR2 = 0.1202 (all
mixture was heated to 80 oC and stirred for 4 h. Then the reaction data), Δe 0.459 and ‒0.260 eÅ3.
mixture was cooled to room temperature, poured into water, and
extracted with dichloromethane for three times. The combined
Conflicts of interest
organic layers were dried over anhydrous magnesium sulfate. After
filtration and solvent evaporation, the residue was purified by silica-
There are no conflicts to declare.
gel column chromatography using petroleum as the eluent. The
white solid product was obtained in 36% yield. 1H NMR (500 MHz,
CDCl3), δ (TMS, ppm): 8.11 (d, J = 2.60 Hz, 2H,), 8.00−7.91 (m, 7H),
Acknowledgements
7.31−7.26 (m, 4H), 7.22−7.18 (m, 1H), 4.38 (s, 2H). 13C NMR (125
MHz, CDCl3), δ (TMS, ppm): 140.3, 137.8, 130.3, 129.9, 128.0, 127.5, This work was financially supported by the National Natural
126.4, 126.1, 125.1, 124.52, 124.49, 123.9, 123.5, 122.2, 41.4. Science Foundation of China (21788102 and 21673082), the
HRMS (C23H16): m/z 292.1289 ([M+], calcd 292.1252).
Guangdong Natural Science Funds for Distinguished Young
Scholar (2014A030306035), the Natural Science Foundation of
Guangdong Province (2016A030312002), Science and
X-Ray crystallography
Technology
Project
of
Guangdong
Province
Crystal data for 1 (CCDC 1533087): C23H13BrO, MW = 385.24, (2016B090907001), the Innovation and Technology
monoclinic, P2(1)/c, a = 9.7948(7), b = 21.5595(13), c = 7.9044(5) Å, Commission of Hong Kong (ITC-CNERC14SC01) and the
β = 104.573(7)o, V = 1615.48(19) Å3, Z = 4, Dc = 1.584 g cm-3, μ = Fundamental Research Funds for the Central Universities
2.552 mm-1 (MoKα, λ = 0.71073), F (000) = 776.0, T = 170 K, 2θmax
=
(2017ZD001).
25.350 (99.8%)o, 2945 measured reflections, 2440 independent
reflections (Rint = 0.0290), GOF on F2 = 1.049, R1 = 0.0446, wR2
0.0745 (all data), Δe 0.750 and ‒0.470 eÅ3.
=
References
Crystal data for
2 (CCDC 1533086): C23H13IO, MW = 432.23,
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Crystal data for 4 (CCDC 1533084): C23H13BrO, MW = 385.24, triclinic,
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Crystal data for 6 (CCDC 1533089): C23H14O, MW = 306.34, triclinic,
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J. Name., 2013, 00, 1-3 | 7
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8 | J. Name., 2012, 00, 1-3
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Apparent AIE phenomenon was observed for 1-benzoyl and 1-benzyl pyrene
derivatives, and the working mechanism was elucidated.