Synthesis and third-order nonlinear optical properties of triphenylene derivatives modified by click chemistry

Article abstract of DOI:10.1002/cphc.201300615

A series of asymmetric triphenylene derivatives containing typical D-π-A structures is successfully synthesized by means of [2+2] cycloaddition- cycloreversion click reactions. The photophysical and electrochemical properties, as well as the click reactio

Full text of DOI:10.1002/cphc.201300615

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DOI: 10.1002/cphc.201300615
Synthesis and Third-Order Nonlinear Optical Properties of
Triphenylene Derivatives Modified by Click Chemistry
Yongsheng Mi, Pengxia Liang, Zhaokui Jin, Dong Wang,* and Zhou Yang*[a]
A series of asymmetric triphenylene derivatives containing typ-
ical D–p–A structures is successfully synthesized by means of
[2+2] cycloaddition–cycloreversion click reactions. The photo-
physical and electrochemical properties, as well as the click re-
actions, are characterized by means of UV/Vis absorption spec-
troscopy, cyclic voltammetry, and DFT modulations. In addition,
the third-order nonlinear properties, including the nonlinear
absorption and the nonlinear susceptibilities, are investigated
by using Z-scan techniques. A typical reverse saturable absorp-
tion–saturable absorption behavior is observed for the third-
order nonlinear absorption, with the third-order nonlinear sus-
ceptibilities of the compounds being 1.05ꢀ10ꢀ12, ꢀ1.50ꢀ
10ꢀ12, and ꢀ0.52ꢀ10ꢀ12 esu, respectively.
1. Introduction
Organic conjugated compounds are widely used in the fields
of electronics and optoelectronics. Many organic molecules ex-
hibiting highly efficient nonlinear optical (NLO) properties have
attracted considerable attention because of their potential ap-
plications in optical communication, optical data storage, pho-
todynamic therapies, three-dimensional memories, and pho-
tonic devices such as optical switches.[1] In particular, organic
p-conjugated third-order NLO materials have been extensively
studied because of their large second hyperpolarizabilities and
their fast response times.[2] Moreover, much work on optimiz-
ing the third-order NLO responses has been performed, reveal-
ing that the amplitude and sign of the g value can be adjusted
by changing the bond length alternation, the strength of the
donor/acceptor substituents, the charge and the size of the p-
conjugation.[3]
One reason that accounts for the disadvantage of TP deriva-
tives as promising NLO materials is that it is costly and time-
consuming to modify the TP derivatives with strong electron
donors and acceptors due to the required tedious chemosyn-
thesis and purification processes. Formal [2+2] cycloaddition–
cycloreversion (CA–CR) reactions between electron alkynes and
electron-deficient alkenes, such as tetracyanoethene (TCNE) or
7,7,8,8-tetracyano-p-quinodi- methane (TCNQ), have been de-
veloped as a convenient and robust method for preparing
nonplanar, p-conjugated, donor–acceptor chromophores that
exhibit intense, low-energy, intramolecular charge transfer (CT)
and high third-order optical nonlinearities.[8] These features
render 1,3-butadiene CA–CR products that are attractive for
NLO applications.[9] The transformations are generally fast,
high-yielding, catalyst-free, and 100% atom-economic, and the
resulting products can be easily purified by precipitation or
washing.
Many papers have been reported on investigations of the
third-order NLO properties of molecules with p-conjugation
systems, such as porphyrins, phthalocyanines, azobenzene,
and so on.[4,5] Triphenylene (TP) has been traditionally chosen
as a building block for the fabrication of photoelectric materi-
als, such as liquid crystals (LCs).[6] It has shown good perfor-
mance in electronic devices, such as thin film transistors, or-
ganic light emitting diodes, and organic solar cells.[7] TP has
been extensively employed as the central core of discotic con-
jugated molecules, which have shown to be rather promising
in optoelectronic applications. However, studies on TP deriva-
tives used in NLO have been rarely reported.
In the present work, [2+2] CA–CR click reactions were se-
lected to synthesize a novel series of asymmetric TP derivatives
with typical D–p–A structures. The physical properties, espe-
cially the third-order nonlinear properties of the pre-click and
after-click compounds, were fully studied and compared. Our
approach opens a new platform for the synthesis of multi-D–
p–A TP derivatives to be used in appropriate photonic applica-
tions.
2. Results and Discussion
2.1. Synthesis
[a] Y. Mi, P. Liang, Z. Jin, Dr. D. Wang, Prof. Dr. Z. Yang
School of Materials Science and Engineering
University of Science and Technology Beijing
Beijing 100083 (China)
Scheme 1 shows the molecular structures and synthetic routes
of compounds ATP1, CATP1, and CATP2. At first, a carbonyl
group was connected to the TP discotic cores through a Frie-
del–Crafts acylation procedure to obtain the asymmetric TP de-
rivative 1 and introduce a strong electron acceptor, the car-
bonyl group. By means of bromination and Hagihara–Sonoga-
E-mail: wangdong_ustb@foxmail.com
yangz@ustb.edu.cn
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cphc.201300615.
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Scheme 1. Molecular structures of ATP, CATP1, CATP2, and their synthetic routes.
shira cross-coupling, N,N-didodecylanilino substituents were in-
troduced as strong electron donors in 1 to give a typical D–p–
A structure product, namely, ATP. The asymmetric TP derivative
was evidenced by typical peaks at 2960, 2874, 2150, and
1605 cmꢀ1, which could be attributed to the vibration absorp-
tions of methyl and methylene, the carbon–carbon triple
bond, and the carbonyl group, respectively. Nuclear magnetic
resonance (1HNMR and 13CNMR), matrix-assisted laser desorp-
tion/ionization time-of-flight mass spectrometry (MALDI-TOF-
MS), differential scanning calorimetry (DSC), and elemental
analysis (EA) results were further used to fully characterize the
products. In the 1HNMR spectra, the hydrogen atoms of the ar-
omatic cores of ATP showed chemical shifts (d) at 6.60~8.98
and the alkyl chains showed relevant shifts at 0.96~3.29. The
13CNMR spectra showed the numbers of carbon atoms that
had different chemical shifts and the DSC curves showed that
the compound has a melting point of 1418C.
CATP1 and CATP2 were obtained through [2+2] cycloaddi-
tion–cycloreversion reactions between ATP and TCNE, TCNQ
with relatively high yielding, as was in Scheme 1. TCNE and
TCNQ were stepwise added to the side chain alkynes of ATP
undergoing a click chemistry-type addition reaction via a [2+
2] cycloaddition followed by a cycloreversion process. With the
introduction of the strong electron-withdrawing cyano groups
in TCNE and TCNQ, more complicated D–p–A structured sys-
tems had been formed. Both products were evidenced by
means of Fourier-transformed infrared (FTIR) spectroscopy for
the appearances of peaks at 2216 cmꢀ1 of cyano groups and
the disappearances of peaks at 2150 cmꢀ1 of carbon–carbon
1
triple bonds. The HNMR spectra of the click-reaction products
showed a low chemical shift at 8.25~6.60 for the H atoms in
the aromatics cores, and the DSC curves showed that CATP1
and CATP2 have melting points of 185 and 1988C, respectively.
The final products were fully characterized by using 13C NMR
and MALDI-TOF-MS spectroscopy.
Formal [2+2] cycloaddition of strong electron acceptors of
TCNE and TCNQ to electron-rich alkynes, followed by retro-
electrocyclization, provides efficient access to nonplanar push–
pull chromophores featuring intense intramolecular charge
transfer (CT) and high third-order optical nonlinearities.[10]
In addition, the [2+2] click-type reaction was characterized
by UV/Vis spectroscopic titration of CATP1. Quantitative TCNE
was added to the dichlorobenzene solution of ATP, and the
obtained absorption spectra are shown in Figure 1, as well as
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Figure 2. UV/Vis absorption spectra and photos of solutions of the products
ATP, CATP1, and CATP2 in dichloromethane.
CATP2 systems showed a bathochromic shift compared to
ATP. This was due to the electron-donor and electron-acceptor
substituents in the synthesized click-type reaction products
CATP1 and CATP2, which increased the charge-transfer charac-
ter.[12] The fact that the CATP2 system exhibits a maximum ab-
sorption at the longest wavelength (750 nm) among the inves-
tigated compounds reflects the highest charge-transfer interac-
tions occurring between the electron-donor (amino) and the
electron-acceptor (cyano) groups. This enhancement of the
charge-transfer efficiency, if compared to CATP1, could be at-
tributed to an increment of the p-conjugated range by the
quinone groups.[13]
Figure 1. a) Reaction of ATP with quantitative TCNE to prepare CATP1.
b) Changes in the UV/Vis absorption spectral shape upon addition of 0 to
2 equiv. TCNE in dichloromethane.
the reaction equation. Upon addition of quantitative TCNE, the
spectra of the reaction showed an obvious increment in the
CT band intensities in the wavelength region near 300 nm and
bathchromical shifts in the near-infrared region. Additionally,
the occurrence of an isoabsorptive point at 423 nm indicated
no side reactions in the [2+2] click-type reaction.
2.3. HOMO–LUMO Energy Gap
Electron delocalization was one of the three main factors af-
fecting the third-nonlinear polarizabilities of organic molecules,
and the charge delocalized on the molecules varied with the
different HOMO/LUMO (highest occupied molecular orbital/
lowest unoccupied molecular orbital) energy levels.[14] Mole-
cules having delocalized p-electrons and compounds consist-
ing of p-conjugated molecules showed a much larger third-
nonlinear susceptibility. To characterize the electron delocaliza-
tion of the studied compounds, cyclic voltammetry (CV) and
DFT simulations were carried out, and the electrochemical
properties of the products are given in Table 1. The HOMO and
LUMO energies of ATP, CATP1, and CATP2 were ꢀ4.95 and
ꢀ3.12, ꢀ5.53 and ꢀ4.15, and ꢀ5.05 and ꢀ4.59 eV, respectively,
and the calculated energy gaps were 1.83 eV for ATP, 1.38 eV
for CATP1, and 0.46 eV for CATP2, showing the lowering of
HOMO–LUMO energy gaps, which is in good agreement with
the energy-gap trends obtained from the onset wavelengths
of UV/Vis absorption shown in Table 1. This can be mainly at-
tributed to increments in the charge-transfer character of both
p–p transitions and donor–acceptor transitions in these typical
D–p–A compounds.
2.2. UV/Vis Spectra
Figure 2 shows the characteristic UV/Vis absorption spectra of
the products ATP, CATP1, and CATP2 in dichloromethane at
a concentration of 1.0ꢀ10ꢀ4 molLꢀ1. As shown in Figure 2, all
the products exhibit intensive absorption bands in the wave-
length region between 300 and 415 nm, which correspond to
So–CT transitions (where So is the singlet state and CT is the
charge-transfer state).[11] Compared to ATP, the click-type reac-
tion product CATP1 showed two additional absorption bands
at 481 (shoulder) and 654 nm, whereas CATP2 showed new
broad absorption bands in the 450–1100 nm region. In addi-
tion, the end absorption peaks (lend) of the products batho-
chromically shifted from ATP (500 nm) to CATP1 (875 nm) and
CATP2 (1095 nm), which could be reflected by the photogra-
phy of products in Figure 2. The absorption spectra indicate
that after the addition of an electron-acceptor (cyano) group
by means of click-type reactions, CATP1 and CATP2 showed
new broad absorption ranges, and the lend of the CATP1 and
Three-dimensional plots of the HOMO and LUMO levels of
ATP, CTAP1, and CATP2, calculated by DFT modulations, are
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ꢀ4.66ꢀ10ꢀ12 mwꢀ1. The Imc(3) values of CATP1 and CATP2
were ꢀ1.50ꢀ10ꢀ12 and ꢀ0.52ꢀ10ꢀ12 esu, while the nonlinear
absorption coefficients b were ꢀ6.66ꢀ10ꢀ12 and ꢀ2.31ꢀ
10ꢀ12 mwꢀ1, respectively. Compared to other organic molecules
measured by Z-scan, the third-order nonlinear values of our
compounds were relatively good.[16,17] CATP1 shows a larger
Imc(3) value compared to ATP, which can be ascribed to the in-
troduction of electron-acceptor (cyano) groups from TCNE and
may help increase the third-order nonlinear susceptibility of
the compound by modifying charge transfer within the mole-
cule.[18] In addition, CATP2 shows a lower Imc(3) value com-
pared to CATP1, which can be attributed to an increment of
the p-conjugated ranges in CATP2 and could have an influ-
ence on the charge transfer, hinering the polarizabilities of the
molecule.[19] The properties of these products are important for
the synthesis of new molecules to be used in NLO applica-
tions.
Table 1. Electrochemical properties of ATP, CATP1, and CATP2.
ox[a]
red[b]
[c]
[d]
optical[e]
Sample Eonset
Eonset
HOMO LUMO Eg
lonset
Eg
[V]
[V]
[eV]
[eV]
[eV] [nm]
[eV]
ATP
CATP1
CATP2
0.15
0.73
0.25
ꢀ1.68
ꢀ0.65
ꢀ0.21
ꢀ4.95
ꢀ5.53
ꢀ5.05
ꢀ3.12 1.83 509
v4.15 1.38 830
ꢀ4.59 0.46 1037
2.43
1.49
1.20
[a] Onset oxidation potentials determined from cyclic voltammograms in
CH2Cl2/Bu4NPF6 at a scan rate of 40 mVsꢀ1. [b] Onset reduction potentials
determined from cyclic voltammograms in CH2Cl2/Bu4NPF6 at a scan rate
of 40 mVsꢀ1. [c] Band gaps estimated from the onset potentials. [d] Onset
wavelength of optical absorption in a dichloromethane solution. [e] Band
gaps estimated from the onset wavelength of optical absorption in a di-
chloromethane solution.
shown in Figure 3. The electron cloud movements through p-
conjugated frameworks from electron-donor to electron-ac-
ceptor groups and the charge delocalized on the molecule
varied with the different HOMO and LUMO energy levels. The
HOMO and LUMO energies of ATP, CATP1, and CATP2 were
ꢀ5.63 and ꢀ1.75, ꢀ5.97 and ꢀ3.89, and ꢀ5.96 and ꢀ3.34 eV,
respectively, at the DFT level. The DFT-calculated energy gaps
of 3.88 eV for ATP, 2.08 eV for CATP1, and 2.62 eV for CATP2
also showed the lowering of energy gaps and reflected the
third-order NLO activities of the molecules.[15]
3. Conclusions
Novel asymmetric TP derivatives, having large conjugated sys-
tems as well as strong D–p–A structures, were synthesized by
means of [2+2] click procedures. Investigations of the photo-
physical and electrochemical properties of the products by
using UV/Vis spectroscopy and CV showed that the CT charac-
ter of the D–p–A structures plays a key role in the absorption-
peak shifts and the HOMO–LUMO energy levels. Most impor-
tantly, upon the introduction of electron acceptors, the third-
order nonlinear absorption of the products showed a typical
RSA–SA transition and the third-order nonlinear susceptibilities
increased. This approach combines the possibility to vary the
structures of the conjugated system with third-order optical
nonlinearities, opening new perspectives to utilize the system
in a variety of photoelectric applications.
2.4. Z-Scan Curves
The NLO responses of ATP, CATP1, and CATP2 were measured
by the “open aperture” Z-scan technique; several recordings
were acquired. All the samples were studied from a 10ꢀ6 m so-
lution in tetrahydrofuran (THF) spectrum pure (SP) and the sol-
vent itself did not show any third-order nonlinearities under
the experimental conditions. The nonlinear absorption coeffi-
cient b was determined using Equation (1) and the imaginary
parts of the third-order nonlinear susceptibility could be calcu-
lated using Equation (2) (see Experimental Section).
Experimental Section
Figure 4 shows the “open aperture” Z-scan data and the nor-
malized transmittance curves of all the products, which could
be perfectly fitted to Equation (1). In Figure 4a, a profound
transmittance valley could be seen around the focal plane,
which is characteristic of the reverse saturable absorption
(RSA)-type behavior of ATP. Materials showing RSA become
more opaque on exposure to high photon fluxes due to the
high absorption from the excited state, and this property has
been exploited in the field of optical limiting for laser protec-
tion. Figure 4b shows the typical transmittance peaks of the
click-reaction products CATP1 and CATP2, which exhibit satu-
rable absorption (SA)-type behaviors. It could be shown that
compared to ATP, the click-reaction products CATP1 and
CATP2 exhibit a clearly reverse saturable absorption–saturable
absorption (RSA–SA) transition, which is achieved by click-type
reactions in the organic molecules.
General Methods
1HNMR and 13CNMR spectra of the samples were recorded with
a Varian 400 MHz instrument, MALDI-TOF-MS spectra were deter-
mined on a Shimadzu AXIMA-CFR mass spectrometer. DSC analyses
were performed on a PerkinElmer Pyris 6 instrument at a heating/
cooling rate of 108Cminꢀ1. All UV/Vis spectra were recorded on
a HITACHI U-3010 spectrophotometer, and FTIR spectra were re-
corded on a PerkinElmer LR-64912C spectrophotometer. Elemental
analyses were performed at the Institute of Chemistry of the Chi-
nese Academy of Sciences using a Flash EA 1112 instrument.
Synthesis of phenyl(triphenylen-2-yl)methanone (1). Tripheny-
lene (5.00 g, 21.9 mmol, 1 equiv) and benzoyl chloride (3.08 g,
21.9 mmol, 1 equiv) were dissolved in dichloromethane (60 mL)
and then the reactor was cooled to 08C. After the portionwise ad-
dition of AlCl3 (4.17 g, 31.3 mmol), the reaction mixture was heated
under reflux for 10 h and then poured into ice-water. The resulting
mixture was stirred until the color of the organic phase turned
from black to yellow and the layers were separated in which the
aqueous phase was extracted with dichloromethane and dried
with anhydrous MgSO4. After evaporation of the solvent in high
vacuum, the residue was purified by column chromatography
From a plethora of recordings, the Imc(3) value of ATP has
been determined according to Equations (1) and (2) (see Exper-
imental Section) and was found to be Imc(3) =1.05ꢀ10ꢀ11 esu,
which corresponds to a nonlinear absorption coefficient of b=
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Figure 3. Electron densities in the HOMOs (bottom) and LUMOs (top) of ATP, CATP1, and CATP2. The atoms are color coded as follows: carbon, gray; nitro-
gen, blue; oxygen, red; hydrogen, white.
(silica gel, dichloromethane/petroleum ether=3/2, v/v) to afford
the pure 1 (5.11 g, 70%). H NMR (400 MHz, CDCl3): d=9.10 (1H, s),
8 h. The cooled reaction suspension was poured into acetone and
the precipitate filtered off. Further drying of the precipitate under
high-vacuum conditions gave the crude product 2 (1.18 g, 80%),
which was used without further purification because of the bad
1
8.79 (1H, d, J=8.0 Hz), 8.71 (3H, m), 8.60 (1H, d, J=8.0 Hz), 8.06
(1H, d, J=8.0 Hz), 7.91 (2H, m), 7.68 (5H, m), 7.54 ppm (2H, m). FT-
IR (KBr): n=1654, 1596, 1264, 812 cmꢀ1. MALDI-TOF-MS (dithranol):
solubility in common organic solvents. FTIR (KBr): n=1648, 1606,
~
~
m/z: calcd for C25H16O: 332.12 gmolꢀ1, found: 332.4 gmolꢀ1 [MH]+.
1271, 955, 757 cmꢀ1
.
Synthesis of (6,10-dibromotriphenylen-2-yl)(phenyl)methane (2):
Compound 1 (1.00 g, 3.01 mmol, 1 equiv) was dissolved in nitro-
benzene (20 mL). Bromine (2.37 g, 15.0 mmol, more than 2 equiv)
was then added slowly under vigorous stirring. After complete ad-
dition, the temperature was heated to 1408C and maintained for
Synthesis of (6,10-bis((4-(dibutylamino)phenyl)ethynyl)tripheny-
len-2-yl)(phenyl)methanone (ATP): Compound (0.50 g,
1.02 mmol, 1 equiv), Pd(PPh3)2Cl2 (14.0 mg, 2.05 mmol), and CuI
(7.81 mg, 4.10 mmol) were added to a degassed solution of TEA
(15 mL) and THF (15 mL) under argon. While stirring, the reaction
2
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(silica gel, ethyl acetate/petroleum
ether=1/4, v/v) to give the pure
CATP2 (0.20 g, 87%). 1HNMR
(400 MHz, CDCl3): d=8.25 (14H,
m), 7.53 (4H, d, J=8.0 Hz), 6.64
(12H, m), 3.32 (8H, m), 1.23 (16H,
m), 0.91 ppm (12H, m). 13CNMR
(100 MHz, CDCl3): d=195.4, 167.4,
153.7, 153.3, 151.4, 150.8, 136.7,
135.6, 134.6, 134.0, 132.8, 132.0,
131.7, 131.2, 130.6, 129.8, 129.3,
128.5, 128.3, 126.1, 125.0, 123.0,
122.8, 114.6, 113.1, 112.4, 111.9,
93.3, 65.2, 50.8, 31.6, 30.2, 29.3,
29.1, 19.9, 18.8, 13.5, 13.4 ppm. FT-
Figure 4. Open-aperture Z-scans measured in a THF solution of: a) ATP and b) CATP1, CATP2. As seen from the
figures, the optical transmission is a function of the sample option (Z=0 is the beam focus). Tnorm is the measured
transmission normalized by the linear transmission of the sample. The solid curves correspond to numerical fits to
the data.
~
IR (KBr): n=2927, 2867, 2216,
1660, 1485, 1186, 833 cmꢀ1
.
mixture was heated to 708C and N,N-dibuty-4-ethynylaniline
(0.47 g, 2.04 mmol, 2 equiv) was injected. After 15 min of stirring at
this temperature, the reaction was continually heated to 808C and
stirred for 8 h under argon atmosphere. The cooled reaction mix-
ture was diluted with CH2Cl2 and extracted with water. The organic
phase was dried with MgSO4 and the solvent was removed under
reduced pressure. The crude product was purified by column chro-
matography (silica gel, dichloromethane/petroleum ether=1/4, v/
v) to give ATP (0.52 g, 65%). 1HNMR (400 MHz, CDCl3): d=8.98
(1H, s), 8.71 (2H, s), 8.10 (11H, m), 7.65 (4H, d, J=8.0 Hz), 6.60 (4H,
d, J=8.0 Hz), 3.29 (8H, m), 1.30 (16H, m), 0.96 ppm (12H, m).
13CNMR (100 MHz, CDCl3): d=195.6, 137.1, 132.9, 132.4, 131.0,
130.6, 129.8, 128.2, 127.9, 127.5, 126.3, 125.9, 125.1, 124.4, 124.2,
MALDI-TOF-MS (dithranol): m/z: calcd. for C81H66N10O:
1194.54 gmolꢀ1, found: 1195.5 gmolꢀ1 [MH]+. Elemental analysis
calcd. (%) for C81H66N10O (1195.46): C 81.37, H 5.52, N 11.69; found:
C 81.38, H 5.56, N 11.72. MP: 1988C.
Nonlinear Optical Studies: Z-Scan Measurement
In our experiments, to investigate the third-order nonlinearities of
the products, Z-scan measurements were performed using a 20 ps
mode-locked Nd:YAG laser at 532 nm. “Open aperture” Z-scan
measurements were carried out to separately determine the imagi-
nary part of the third-order nonlinear susceptibility c(3) and the
nonlinear absorption coefficient b, which is related to the nonlinear
absorption of the samples. Additionally, the advantage of the Z-
scan measurements is that apart from the magnitude, they can
also provide the sign of Imc(3), where the latter is directly related
to the nonlinear absorption type [saturable absorption (SA) or re-
verse saturable absorption (RSA)].
~
122.9, 121.9, 111.0, 50.4, 29.4, 29.1, 20.0, 13.7 ppm. FTIR (KBr): n=
2960, 2874, 2150, 1605, 1514, 1365, 1178, 860, 818 cmꢀ1. MALDI-
TOF-MS (dithranol): m/z: calcd. for C57H58N2O: 786.45 gmolꢀ1
,
found: 787.1 gmolꢀ1 [MH]+. Elemental analysis calcd. (%) for
C57H58N2O (787.08): C 86.97, H 7.37, N 3.55; found: C 86.98, H 7.43,
N 3.56. MP: 1418C.
Details of the experimental techniques, as well as the procedure to
analyze the experimental data, are only briefly described here. Ex-
tended information can be found in the literature. Here, a laser
beam is focused using a lens and passed through the sample. The
beam’s propagation direction is taken as the z axis, and the focal
point is taken as Z=0. The beam will have a maximum energy
density at the focus, which will symmetrically reduce toward either
side for the positive and negative values of Z. In our experiments,
THF solutions of the samples were taken in 1 mm cuvettes and the
measurements were performed by placing the samples in the
beam at different positions with respect to the focus (different
values of z) and measuring the corresponding light transmission.
The graph plotted between the samples T (norm) (transmission
normalized to the linear transmission of the sample) is known as
the Z-scan curve. From the “open aperture” Z-scan curves, the non-
linear absorption coefficient b was determined using Equation (1):
Synthesis of 3, 3’-(10-benzoyltriphenylene-2,6-diyl)bis(2-(4-(di-
butylamino)phenyl)buta-1,3-di-ene-1,1,4,4-tetracarbonitrile)
(CATP1): ATP (0.15 g, 0.20 mmol, 1 equiv) and TCNE (51.2 mg,
0.40 mmol, 2 equiv) were mixed in dichloromethane (10 mL). After
stirring for several minutes, the solvent was removed under re-
duced pressure and the crude product was purified by column
chromatography (silica gel, ethyl acetate/petroleum ether=1/4, v/
v) to give the final click-type reaction product CATP1 (0.18 g,
1
89%). HNMR (400 MHz, CDCl3): d=8.23 (14H, m), 7.47 (4H, d, J=
8.0 Hz), 6.60 (4H, d, J=8.0 Hz), 3.29 (8H, m), 1.36 (16H, m),
0.96 ppm (12H, m). 13CNMR (100 MHz, CDCl3): d=195.7, 167.6,
153.9, 153.4, 151.6, 150.9, 136.9, 135.7, 134.8, 134.1, 133.9, 133.0,
130.2, 131.2, 130.6, 128.8, 128.3, 126.1, 125.0, 123.0, 122.8, 114.6,
113.1, 112.1, 111.9, 93.3, 65.2, 51.3, 31.6, 30.2, 29.8, 29.5, 20.4,
~
14.0 ppm. FTIR (KBr): n=2927, 2867, 2216, 1660, 1485, 1186,
818 cmꢀ1. MALDI-TOF-MS (dithranol): m/z: calcd. for C69H58N10O:
1042.48 gmolꢀ1, found: 1043.3 gmolꢀ1 [MH]+. Elemental analysis
calcd. (%) for C69H58N10O (1043.27): C 79.36, H 5.56, N 13.42; found:
C 79.44, H 5.60, N 13.43. MP: 1858C.
pffiffiffi
2
2½1 ꢀ TðZ ¼ 0Þꢁ
bðm wꢀ1Þ ¼
ð1Þ
I0Leff
Synthesis of 2,2’-(2,2’-(10-benzoyltriphenylene-2,6-diyl)bis(1-(4-
(dibutylamino)phenyl)-2-(4-(dicyanomethylene) cyclohexa-2,5-di-
enylidene)ethan-2-yl-1-ylidene))dimalononi trile (CATP2): ATP
(0.15 g, 0.20 mmol, 1 equiv) and TCNQ (0.08 g, 0.40 mmol, 2 equiv)
were dissolved in dichlorobenzene (10 mL). Under stirring, the re-
actor was heated to 1408C and maintained for 1 h. The solvent of
the cooled reaction mixture was removed under reduced pressure
and the crude product was purified by column chromatography
where T is the normalized transmittance, Leff ¼ ð1 ꢀ expðꢀa0LÞÞ=a0
is the effective thickness of the sample, a0 is the linear absorption
coefficient of the sample at the laser excitation wavelength, L is
the sample thickness, and I0 is the on-axis irradiance at the focus.
The beam waist w0 at the Z=0 was 12.6 mm, the parameter Z0 was
0.94, the pulse repetition rate of the laser was 10 Hz, and the I0 in-
tensity was 3.11 GWcmꢀ2. From the nonlinear absorption coeffi-
cient, the imaginary part of the third-order nonlinear susceptibility
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ChemPhysChem 2013, 14, 4102 – 4108 4107

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c2n20b
Imcð3ÞðesuÞ ¼
240 p2w
ð2Þ
where c is the speed of light in cmsꢀ1, n0 is the linear refractive
2 pc
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Keywords: click chemistry · D–p–A structures · nonlinear
optics · synthesis · triphenylene derivatives
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Received: July 1, 2013
Revised: October 11, 2013
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ChemPhysChem 2013, 14, 4102 – 4108 4108