Carbazole-based aggregation-induced emission (AIE)-active gold(I) complex: Persistent room-temperature phosphorescence, reversible mechanochromism and vapochromism characteristics

Article abstract of DOI:10.1016/j.dyepig.2017.05.003

A carbazole-based gold(I) complex 1 has been successfully synthesized. Its structure was characterized by nuclear magnetic resonance spectroscopy, elemental analysis and single crystal X-ray diffractometry. Its aggregation-induced emission behavior was studied by ultraviolet/visible, photoluminescence spectroscopy and scanning electron microscope. Its solid-state mechanochromic and thin-film vapochromic luminescence behaviors were also investigated by photoluminescence spectroscopy. The results demonstrated that luminogen 1 showed obvious aggregation-induced emission property. Furthermore, 1 also exhibited reversible high-contrast mechanochromic and vapochromic luminescence behaviors. More interestingly, 1 can emit persistent room-temperature phosphorescence with a solid-state emission lifetime up to 86.84?ms, which is the highest lifetime value among all the reported gold(I) complexes so far. To the best of our knowledge, the gold(I) complex is the first example of an AIE-active luminogen with persistent room-temperature phosphorescence, reversible mechanochromism and vapochromism characteristics.

Full text of DOI:10.1016/j.dyepig.2017.05.003

Accepted Manuscript
Carbazole-based aggregation-induced emission (AIE)-active gold(I) complex:
Persistent room-temperature phosphorescence, reversible mechanochromism and
vapochromism characteristics
Zhao Chen, Gang Liu, Shouzhi Pu, Sheng Hua Liu
PII:
S0143-7208(17)30175-4
10.1016/j.dyepig.2017.05.003
DYPI 5965
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 26 January 2017
Revised Date: 30 April 2017
Accepted Date: 2 May 2017
Please cite this article as: Chen Z, Liu G, Pu S, Liu SH, Carbazole-based aggregation-induced
emission (AIE)-active gold(I) complex: Persistent room-temperature phosphorescence, reversible
mechanochromism and vapochromism characteristics, Dyes and Pigments (2017), doi: 10.1016/
j.dyepig.2017.05.003.
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ACCEPTED MANUSCRIPT
Carbazole-based aggregation-induced emission (AIE)-active gold(I)
complex: persistent room-temperature phosphorescence, reversible
mechanochromism and vapochromism characteristics
Zhao Chen a, Gang Liu a, Shouzhi Pu a, **, Sheng Hua Liu b, *
Synopsis
A carbazole-based gold(Ι) complex was successfully synthesized. The complex is
AIE-active, and it can emit persistent room-temperature phosphorescence. Moreover,
the luminogen exhibits reversible mechanochromism and vapochromism
characteristics.

ACCEPTED MANUSCRIPT
Carbazole-based aggregation-induced emission (AIE)-active gold(I)
complex: persistent room-temperature phosphorescence, reversible
mechanochromism and vapochromism characteristics
Zhao Chen a, Gang Liu a, Shouzhi Pu a, **, Sheng Hua Liu b, *
a Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology
Normal University, Nanchang 330013, PR China.
b Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, College
of Chemistry, Central China Normal University, Wuhan 430079, PR China.
Tel: +86-791-83831996 Fax: +86-791-83831996
** Corresponding author E-mail: pushouzhi@tsinghua.org.cn
* Corresponding author E-mail: chshliu@mail.ccnu.edu.cn
ABSTRACT
A carbazole-based gold(Ι) complex 1 has been successfully synthesized. Its structure
was characterized by nuclear magnetic resonance spectroscopy, elemental analysis
and single crystal X-ray diffractometry. Its aggregation-induced emission behavior
was studied by ultraviolet/visible, photoluminescence spectroscopy and scanning
electron microscope. Its solid-state mechanochromic and thin-film vapochromic
luminescence behaviors were also investigated by photoluminescence spectroscopy.
The results demonstrated that luminogen 1 showed obvious aggregation-induced
emission property. Furthermore, 1 also exhibited reversible high-contrast
mechanochromic and vapochromic luminescence behaviors. More interestingly, 1
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can emit persistent room-temperature phosphorescence with a solid-state emission
lifetime up to 86.84 ms, which is the highest lifetime value among all the reported
gold(I) complexes so far. To the best of our knowledge, the gold(Ι) complex is the
first example of an AIE-active luminogen with persistent room-temperature
phosphorescence, reversible mechanochromism and vapochromism characteristics.
Keywords: Gold(I) complex; Carbazole; Aggregation-induced emission; Persistent
room-temperature phosphorescence; Mechanochromism; Vapochromism
1. Introduction
The development of efficient luminescent materials has received a great deal of
attention both in fundamental science and practical applications [1-3]. Especially,
smart luminescent materials responding to external stimuli have attracted increasing
interest due to their potential applications in the fields of sensors, security inks and
optoelectronic devices [4-8]. Mechanochromic emissive materials, as a class of smart
luminescent materials, have aroused widespread concern [9-12]. Vapochromic
materials, which involve luminescent changes upon exposure to volatile organic
vapors, are also one promising type of smart luminescent materials [13-19]. High
aggregative-state emission and obvious color contrast before and after stimulating
are two extremely important factors for the highly efficient application of
stimuli-responsive smart materials [20]. However, most conventional luminogens
commonly show poor aggregate state emission efficiency because of the presence of
notorious aggregation caused quenching (ACQ) phenomenon [21], which blocks the
effective development of stimuli-responsive materials. Fortunately, a new
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photophysical process of aggregation-induced emission (AIE) was discovered by
Tang et al. in 2001 [22]. The luminogens possessing AIE effect can achieve bright
luminescence by the aggregate formation. Therefore, it is very significant to
synthesize multistimuli-responsive AIE materials with mechanochromism and
vapochromism characteristics. Over the past two decades, gold(I) chemistry has
aroused the interest of many researchers owing to the occurrence of fascinating
aurophilic interactions between gold centers [23-32]. To date, nevertheless,
AIE-active gold(I) complexes with mechanochromic and vapochromic behaviors are
rather rare [28,30,33-35].
Carbazole-based luminescent materials are valuable candidates in the domain of
photoelectronic devices [36-39]. Unfortunately, the ACQ effect hinders the
high-efficiency application of these luminescent materials containing carbazole unit.
Thus, it is a meaningful research topic to design and synthesize carbazole-based
derivatives with AIE property. On the other hand, most phosphorescence-emitting
metal complexes with mechanochromism behavior exhibit short phosphorescence
lifetimes (< 1 ms) [40-42], and metal complex simultaneously possessing persistent
room-temperature phosphorescence and reversible mechanochromism characteristics
has yet to be reported, not to mention AIE-active vapochromic gold(I) complex with
these intriguing properties. In this work, we described a carbazole-based
mononuclear gold(Ι) complex 1 (Chart 1). AIE, mechanochromism and
vapochromism characteristics of the luminogen were systematically investigated. 1
exhibited obvious AIE behavior, Furthermore, 1 also showed reversible
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high-contrast mechanochromic and vapochromic luminescence. More importantly, 1
can emit persistent solid-state room-temperature phosphorescence with luminescence
lifetime up to 86.84 ms.
Insert Chart 1
2. Materials and methods
2.1. Experimental
General: All manipulations were carried out under an argon atmosphere by using
standard Schlenk techniques, unless otherwise stated. The starting material carbazole
purchased from Alfa Aesar was used as received. CH2Cl2 was dried with CaH2 then
distilled. All other starting materials and reagents were obtained as analytical-grade
from commercial suppliers and used without further purification. Compound 1-b [43]
and C6F5Au(tht) (tht = thiophane) [44] were prepared by procedures described in the
1
corresponding literatures. H NMR (400 MHz) and 13C NMR (100 MHz) spectra
1
were collected on American Varian Mercury Plus 400 spectrometer (400 MHz). H
NMR spectra are reported as followed: chemical shift in ppm (δ) relative to the
chemical shift of TMS at 0.00 ppm, integration, multiplicities (s = singlet, d =
13
doublet, t = triplet, m = multiplet), and coupling constant (Hz). C NMR chemical
shifts reported in ppm (δ) relative to the central line of triplet for CDCl3 at 77 ppm.
19F NMR chemical shifts are relative to C6F6 (δ = -163.00). EI-MS was obtained
using Thermo scientific DSQ II. Elemental analyses (C, H, N) were carried out with
a PE CHN 2400 analyzer. Ultraviolet/Visible spectra were obtained on U-3310 UV
Spectrophotometer. Fluorescence spectra were recorded on a Hitachi-F-4500
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fluorescence spectrophotometer and Fluoromax-P luminescence spectrometer
(HORIBA JOBIN YVON INC.). Luminescent decay experiment was measured by
Edinburgh FLS980 spectrometer. XRD studies were recorded on a Shimadzu
XRD-6000 diffractometer using Ni-filtered and graphite-monochromated Cu Kα
radiation (λ = 1.54 Å, 40 kV, 30 mA). The N, N-dimethyl formamide (DMF)/water
mixtures with various water fractions were prepared by slowly adding ultra-pure
water into the DMF solution of samples. Absolute luminescence quantum yields
were measured by HAMAMATSU ABSOLUTE PL QUANTUM YIELD
SPECTROMETER C11347. Dynamic light scattering (DLS) measurements were
performed on the Zetasizer instrument ZEN3600 (Malvern, UK) with a 173° back
scattering angle and He-Ne laser (λ = 633 nm). The X-ray crystal-structure
determination of complex 1 was obtained on a Bruker APEX DUO CCD system. The
aggregate behavior and the solid-state surface morphology of 1 were investigated by
scanning electron microscopy (SEM, Zeiss, Sigma). Column chromatographic
separations were carried out on silica gel (200-300 mesh). TLC was performed by
using commercially prepared 100-400 mesh silica gel plates (GF254) and
visualization was effected at 254 nm.
2.2 Synthesis
2.2.1 Synthesis of monoisocyano ligand 1-d
Synthesis of 1-c: A mixture of compound 1-b (3.0 g, 11.6 mmol), formic acid
(30 ml) were stirred for overnight at 110ꢀ. After completion of present reaction,
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formic acid was removed from reaction system by distillation, the residual mixture
was extracted with dichloromethane (3 × 30 mL), the combined organic layers were
washed with brine, dried (Na2SO4), and concentrated in vacuo. The residues were
purified by column chromatography, affording the expected pale solid product in a
yield of 83%. 1H NMR (400 MHz, CDCl3): δ (ppm) = 8.83-8.46 (m, 1H), 8.16-8.13
(m, 2H), 7.77 (d, J = 8 Hz, 1H), 7.58-7.52 (m, 2H), 7.44-7.27 (m, 8H). 13C NMR
(100 MHz, CDCl3): δ (ppm) = 162.5, 159.1, 140.8, 140.8, 135.9, 135.8, 134.8, 134.0,
128.5, 127.8, 126.0, 126.0, 123.3, 123.3, 121.2, 120.4, 120.3, 120.1, 120.0, 109.6,
109.5. EI-MS: m/z = 286.16[M]+. Anal. Calcd. for C19H14N2O: C, 79.70; H, 4.93; N,
9.78. Found: C, 79.74; H, 4.95; N, 9.75.
Synthesis of 1-d: A CH2Cl2 suspension (15 ml) of 1-c (1.0 g, 3.5 mmol) and
triethylamine (5 ml) was cooled to 0ꢀ. To the mixture was added dropwise a
CH2Cl2 solution (10 ml) of triphosgene (1.16 g, 3.9 mmol). The mixture was refluxed
under an argon atmosphere for 3 h, then 10% aq. Na2CO3 (50 ml) was added
dropwise at room temperature. the mixture was extracted with dichloromethane (3 ×
30 mL). The combined organic layers were washed with brine, dried (Na2SO4), and
concentrated in vacuo. The residues were purified by column chromatography,
1
affording the expected gray solid product in a yield of 77%. H NMR (400 MHz,
CDCl3): δ (ppm) = 8.14 (d, J = 8 Hz, 2H), 7.63 (s, 4H), 7.45-7.30 (m, 6H). 13C NMR
(100 MHz, CDCl3): δ (ppm) = 165.3, 140.2, 138.7, 128.0, 127.7, 126.2, 123.7, 120.6,
120.4, 109.4. EI-MS: m/z = 268.14[M]+. Anal. Calcd. for C19H12N2: C, 85.05; H,
4.51; N, 10.44. Found: C, 85.02; H, 4.55; N, 10.41.
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2.2.2 Synthesis of complex 1 containing mononuclear gold(I) unit
Synthesis of 1: A mixture of C6F5Au(tht) (0.26 g, 0.57 mmol) and 1-d (0.15 g,
0.56 mmol) was stirred in CH2Cl2 (20 ml) over night under an argon atmosphere at
room temperature. After completion of present reaction, the solvent was evaporated.
A small amount of CH2Cl2 was added, and then a lot of n-hexane was added.
Collecting the white solid product by suction filtration. Yield = 93%. 1H NMR (400
MHz, CDCl3): δ (ppm) = 8.15 (d, J = 8 Hz, 2H), 7.80 (s, 4H), 7.46-7.34 (m, 6H). 19F
NMR (CDCl3): δ (ppm) = -116.60, -157.80, -162.87. Anal. Calcd. for C25H12AuF5N2:
C, 47.49; H, 1.91; N, 4.43. Found: C, 47.56; H, 1.95; N, 4.38.
Insert Scheme 1
3. Results and discussion
3.1. Synthesis
The carbazole-based mononuclear gold(I) complex 1 was prepared according to
the corresponding synthetic strategy presented in Scheme 1. The intermediate
product 1-d as starting material reacted with C6F5Au(tht) (tht = thiophane) to afford
the target gold(I) complex 1 in 93% yield.
3.2. Crystallographic details
Single crystals of complex 1 suitable for X-ray analysis were obtained by slow
diffusion of n-hexane into its dilute solution of dichloromethane. A crystal of 1 with
approximate dimensions of 0.30 × 0.05 × 0.02 mm3 for 1 was mounted on a glass
fiber for diffraction experiment. Intensity data were collected on a Nonius Kappa
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CCD diffractometer with Mo Kα radiation (0.71073 Å) at room temperature. The
structures were solved by a combination of direct methods (SHELXS-97) [45] and
Fourier difference techniques and refined by full-matrix least-squares (SHELXL-97)
[46]. All non-H atoms were refined anisotropically. The hydrogen atoms were placed
in the ideal positions and refined as riding atoms. Further crystal data are provided in
Table S1 (Supporting Information). The selective bond lengths and angles can be
found in Table S2 (Supporting Information). Crystallographic data for the structure
in this paper have been deposited with the Cambridge Crystallographic Data Centre
as supplemental publication CCDC 1516083.
3.3. Aggregation Induced Emission (AIE)
To investigate the aggregation-induced property of luminogen 1, the ultraviolet
(UV)/visible-absorbance spectra of 1 (10 µM) in DMF-H2O mixtures with different
water fractions (fw) were studied (Supporting Information: Fig. S1). The result
demonstrated that the absorption peak of 1 at around 336 nm was red-shifted as the
water content was increased. Meanwhile, the absorption spectra exhibited level-off
tails in the long-wavelength region as the fw values were increased. Such spectral
tails are caused by the Mie scattering effect, which commonly implies the generation
of nanoscopic aggregates [47,48]. As shown in Fig. 1, one emission band with a
maximum (λmax) at 395 nm was observed when a dilute DMF solution of 1 was
excited at 330 nm, and almost no luminescence was noticed under 365 nm UV light.
However, when the water volume fraction in the DMF solution was increased to
50%, 1 showed faint blue luminescence, likely due to the restricted intramolecular
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rotation of carbazole unit [49]. When the fw value was 60%, two new emission bands
were observed with λmax at 425 nm and 530 nm, and 1 displayed faint yellow-green
light emission under 365 nm UV light. At fw = 90%, the mixture exhibited a strong
yellow-green emission. This is because water is a nonsolvent of luminogen 1 and
thus aggregation will happen as the increase of the fw value. Clearly, the bright
yellow-green luminescence of 1 can be attributed to the aggregate formation. Indeed,
the nano-aggregates obtained were confirmed using dynamic light scattering (DLS).
The DLS experimental results indicated the real existence of nano-aggregates.
Meanwhile, the size of nano-aggregates became smaller with the fw increased
(Supporting Information: Fig. S2). Furthermore, the aggregate behavior of 1 was
also explored via scanning electron microscope (SEM). The SEM image indicated
that 1 molecules tended to aggregate in the DMF/H2O mixture with fw = 90%
(Supporting Information: Fig. S3). Obviously, complex 1 is AIE-active, and its AIE
behavior is possibly triggered by the synergistic effects of the restricted
intramolecular rotation and the formation of intermolecular gold-gold interactions
[50].
Insert Figure 1
3.4.
Reversible
Mechanochromism
and
persistent
room-temperature
phosphorescence characteristics of complex 1
The reversible mechanochromic effect of complex 1 was surveyed by
solid-state photoluminescence (PL) spectroscopy. As presented in Fig. 2, the
as-synthesized solid sample of 1 exhibited strong yellow emission with an absolute
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luminescence quantum yield up to 22.5% at 462 nm, 550 nm and 598 nm.
Intriguingly, a persistent yellow room-temperature phosphorescence could be
observed when the 365 nm UV light was turned off (see Movie S1). As evident from
Fig. 3, the emission lifetime of 1 was as high as 86.84 ms, which is the highest
lifetime value among all the reported gold(I) complexes. In addition, upon gentle
grinding of solid sample 1 using a pestle or a spatula, a new emission band with the
λmax at 538 nm was visible, and the yellow-green light-emitting powder was formed.
Its absolute luminescence quantum yield was 19.8%, and its emission lifetime was
1.44 ꢀs (Supporting Information: Fig. S4). The emission peak at 538 nm is
correspond to those observed in DMF/water mixtures with high fw values. After
fuming with dichloromethane solvent vapor for 30 s, the original yellow emitting
condition was completely restored. Furthermore, the reversible mechanochromic
conversion between yellow and yellow-green emission colors could be repeated
many times without fatigue (Fig. 4). The experimental results of SEM showed that
the crystal packing of solid sample 1 may readily collapse upon gentle grinding.
(Supporting Information: Fig. S5). To gain insight into the mechanochromic
mechanism of complex 1, X-ray diffraction (XRD) measurements of various solid
states of 1 were performed. As can be seen in Fig. 5, the as-prepared solid sample
showed a lot of sharp and intense diffraction peaks, which indicated its crystalline
nature. In contrast, the XRD diffractogram of the ground sample did not exhibit any
noticeable reflection peaks, indicative of its amorphous nature. When the
yellow-green light-emitting sample was fumigated with dichloromethane solvent
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vapor, the sharp and intense diffraction peaks coinciding with those in the untreated
sample was attained again, suggesting the recovery of the ordered crystalline state.
Therefore, the mechanochromic phenomenon observed in coordination compound 1
is associated with the morphological transition between the ordered crystalline phase
and the disordered amorphous phase. As shown in Fig. 6, the shortest intermolecular
Au···Au distances are 4.699 Å, indicating lack of strong intermolecular aurophilic
interactions [51]. In addition, the distances between Au-π are 2.056 Å and 2.049 Å,
and the distances between Au-CN are 1.931 Å and 1.982 Å. Furthermore, multiple
weak intermolecular C-H···π interactions (d = 2.566 Å) as well as C-H···F
interactions (dH···F = 2.514 Å, 2.586 Å, 2.617 Å) exist in the crystals, which facilitate
the molecular packing, suppress free rotation of molecular structure and then
promote the formation of long lifetime phosphorescence [52-55]. The emission color
of the single crystal is bright yellow, and its emission spectrum is shown in Fig. S6
(Supporting Information). Meanwhile, the absence of a strong intermolecular acting
force will allow slipping of the molecular stacks upon exposure to external
mechanical stimulus. When solid powder 1 is ground, a metastable amorphous state
is formed, and changes in weak intermolecular C-H···π and C-H···F interactions and
the formation of intermolecular aurophilic interactions are responsible for the
significative mechanochromism behavior of 1[33].
Insert Figure 2
Insert Figure 3
Insert Figure 4
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Insert Figure 5
Insert Figure 6
3.5. Reversible thin-film vapochromic luminescence behavior of complex 1
The thin-film vapochromic luminescence property of complex 1 was evaluated
by PL spectroscopy. Luminogen 1 is highly soluble in common solvents, which
allows convenient solution processing and the formation of thin film. The PL
spectral changes of 1 in response to vapors of frequently-used volatile organic
compounds (VOCs) are shown in Fig. 7. The thin film of 1 showed bright
yellow-green luminescence with the λmax at 530 nm. However, when the thin film
was exposed to vapors of different VOCs, including dichloromethane,
trichloromethane, tetrahydrofuran, 1,4-dioxane, benzene, acetone, toluene,
acetonitrile, diethyl ether, ethyl acetate, etc., the yellow emission with the λmax at
around 578 nm was observed. This red-shifted emission is related to that observed in
the solid state emission (Fig. 2). The existence of different solvents molecules
possibly resulted in the formation of intermolecular acting force, which altered the
molecular stacking and intermolecular distance between the shortest Au atoms, and
then changed the emission color from green to yellow [29]. Furthermore, the initial
yellow-green emission reappeared when the thin film was removed from the
different VOCs vapors. Thus, luminogen 1 also exhibited reversible vapochromic
luminescence behavior.
Insert Figure 7
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4. Conclusions
We report a carbazole-based mononuclear gold(Ι) complex. The complex is an
interesting luminophor as it exhibits obvious AIE behavior, and its solid sample can
emit persistent room-temperature phosphorescence with luminescence lifetime up to
86.84 ms, which is the highest lifetime value among all the reported gold(I)
complexes so far. In addition, the luminogen also shows reversible high-contrast
mechanochromism and vapochromism characteristics. To the best of our knowledge,
this mononuclear gold(Ι) complex is the first example of an AIE-active luminogen
with persistent room-temperature phosphorescence, reversible mechanochromic and
vapochromic behaviors. It is believed that the multifunctional gold(I) complex will
be outstanding candidate in the field of multistimuli-responsive materials.
Furthermore, this work will also be beneficial to the design of new AIE-active
metal-bearing luminogens with multistimuli-responsive behaviors and persistent
room-temperature phosphorescence characteristics. Further explorations of gold(Ι)
complexes with other significative properties are in progress.
Acknowledgments
The authors are grateful for the financial support from the National Natural
Science Foundation of China (51373072, 201362013, 21662015, and 21472059), the
Project of Jiangxi Sci-Tech Innovative Team (20142BCB24012), the Project of
Jiangxi Academic and Technological leader (20142BCB22010), and the Project of
the Science Fund of Jiangxi Education Office (GJJ160764).
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Supporting Information Available
UV/visible-absorbance spectra of complex 1 (1.0 × 10-5 mol L-1) in DMF-H2O
mixtures with different water contents. Size distribution curves of complex 1 (1.0 ×
10-5 mol L-1) in DMF-water mixtures with 60% and 90% volume fractions of water.
SEM images and characterization data mentioned in the paper. Details of the crystal
data collection, and selective bond lengths and angles.
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Table of Contents
1. Chart 1. (a) The structure of complex 1. (b) The configuration of a gold(I) complex
molecule taken form the single crystal structure.
2. Scheme 1. Synthetic route to the carbazole-based gold(I) complex 1.
3. Figure 1. (a) Photoluminescence (PL) spectra of the dilute solutions of luminogen
1 (1.0 × 10-5 mol L-1) in a mixture of DMF-H2O with different water contents
(0-60%). Excitation wavelength = 330 nm. The inset shows the emission images of 1
(1.0 × 10-5 mol L-1) in pure DMF, 50% water fraction and 60% water fraction under
irradiation with UV light at 365 nm. (b) PL spectra of the dilute solutions of
luminogen 1 (1.0 × 10-5 mol L-1) in a mixture of DMF-H2O with various water
contents (60-90%). Excitation wavelength = 330 nm. The inset shows the emission
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images of 1 (1.0 × 10-5 mol L-1) in 60% water fraction as well as 90% water fraction
under irradiation with UV light at 365 nm.
4. Figure 2. (a) Solid-state PL spectra of complex 1 before grinding, after grinding,
and after treatment with dichloromethane solvent vapor. Excitation wavelength: 365
nm. Photographic images of 1 under 365 nm UV light: (b) the as-synthesized solid
sample. (c) the ground solid sample. (d) the solid sample after treatment with
dichloromethane solvent vapor.
5. Figure 3. Decay curve of the gold(I) complex at the peak emission wavelength of
550 nm. Excitation wavelength: 365 nm.
6. Figure 4. Reversible change in PL peak intensity (538 nm) of the gold(I) complex
recorded for several grinding-fuming processes.
7. Figure 5. X-ray diffraction (XRD) patterns of gold(I) complex 1 in different solid
states: the as-prepared solid, the ground powder and the solid after treating the ground
sample with dichloromethane vapor.
8. Figure 6. The molecular packing of the coordination compound 1 in a single
crystal cell. The dashed lines are showing the distances between the correlation atoms
in the crystal. The H, C, N, F, and Au atoms are colored in light grey, dark grey, blue,
yellow and pink, respectively.
9. Figure 7. (a) Emission spectra of luminogen 1 thin film, exposed to different VOCs
vapors and away from different VOCs vapors. Excitation wavelength: 365 nm. (b)
Photographic images of 1 thin film, exposed to different VOCs vapors and away from
different VOCs vapors under 365 nm UV light.
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Chart 1. (a) The structure of complex 1. (b) The configuration of a gold(I) complex
molecule taken form the single crystal structure.
Scheme 1. Synthetic route to the carbazole-based gold(I) complex 1.
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Figure 1. (a) Photoluminescence (PL) spectra of the dilute solutions of
luminogen 1 (1.0 × 10-5 mol L-1) in a mixture of DMF-H2O with different water
contents (0-60%). Excitation wavelength = 330 nm. The inset shows the emission
images of 1 (1.0 × 10-5 mol L-1) in pure DMF, 50% water fraction and 60% water
fraction under irradiation with UV light at 365 nm. (b) PL spectra of the dilute
solutions of luminogen 1 (1.0 × 10-5 mol L-1) in a mixture of DMF-H2O with various
water contents (60-90%). Excitation wavelength = 330 nm. The inset shows the
emission images of 1 (1.0 × 10-5 mol L-1) in 60% water fraction as well as 90% water
fraction under irradiation with UV light at 365 nm.
Figure 2. (a) Solid-state PL spectra of complex 1 before grinding, after grinding,
and after treatment with dichloromethane solvent vapor. Excitation wavelength: 365
nm. Photographic images of 1 under 365 nm UV light: (b) the as-synthesized solid
sample. (c) the ground solid sample. (d) the solid sample after treatment with
dichloromethane solvent vapor.
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Figure 3. Decay curve of the gold(I) complex at the peak emission wavelength
of 550 nm. Excitation wavelength: 365 nm.
grinding
fuming
0
2
4
6
8
10
Number of cycles
Figure 4. Reversible change in PL peak intensity (538 nm) of the gold(I)
complex recorded for several grinding-fuming processes.
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unground
ground
treated with CH Cl
2
2
10
20
30
40
50
2
θ
(degree)
Figure 5. X-ray diffraction (XRD) patterns of gold(I) complex 1 in different
solid states: the as-prepared solid, the ground powder and the solid after treating the
ground sample with dichloromethane vapor.
Figure 6. The molecular packing of the coordination compound 1 in a single
crystal cell. The dashed lines are showing the distances between the correlation atoms
in the crystal. The H, C, N, F, and Au atoms are colored in light grey, dark grey, blue,
yellow and pink, respectively.
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Figure 7. (a) Emission spectra of luminogen 1 thin film, exposed to different
VOCs vapors and away from different VOCs vapors. Excitation wavelength: 365 nm.
(b) Photographic images of 1 thin film, exposed to different VOCs vapors and away
from different VOCs vapors under 365 nm UV light.
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Highlights
ꢀ A carbazole-based mononuclear gold(Ι) complex was synthesized.
ꢀ The gold(Ι) complex exhibits obvious aggregation-induced emission (AIE) property.
ꢀ The gold(Ι) complex can emit persistent room-temperature phosphorescence with a
solid-state emission lifetime up to 86.84 ms.
ꢀ The gold(Ι) complex shows reversible mechanochromic luminescence behavior.
ꢀ The gold(Ι) complex shows reversible vapochromic luminescence behavior.