Multi-photon properties in various condensed phases of dendritic chromophores derived from carbazole and indenoquioxaline units: Synthesis and characterization

Article abstract of DOI:10.1016/j.dyepig.2019.04.044

We have used functionalized carbazoles and indenoquonoxalines as the main building units and enthynyl groups as the π-linkages to construct two novel dendritic fluorophores and studied their degenerate multi-photon absorption properties in both the solution phase and the neat-film state within femtosecond and nanosecond regions. In our experiments, these model compounds are found to manifest strong and widely dispersed two-photon absorption as well as effective power-limiting properties against ultra-short laser pulses in the near-IR region. In addition, both chromophores exhibit medium to strong three-photon-induced fluorescence, indicating such scaffold may serve as a reference structural motif for the development of three-photon materials.

Full text of DOI:10.1016/j.dyepig.2019.04.044

Accepted Manuscript
Multi-photon properties in various condensed phases of dendritic chromophores
derived from carbazole and indenoquioxaline units: Synthesis and characterization
Tzu-Chau Lin, Wei Chien, Shu-Wen Dai, Hao-Wu Lin, Yueh-Ching Liu
PII:
S0143-7208(18)31984-3
https://doi.org/10.1016/j.dyepig.2019.04.044
DYPI 7499
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 11 September 2018
Revised Date: 5 April 2019
Accepted Date: 17 April 2019
Please cite this article as: Lin T-C, Chien W, Dai S-W, Lin H-W, Liu Y-C, Multi-photon properties in
various condensed phases of dendritic chromophores derived from carbazole and indenoquioxaline
units: Synthesis and characterization, Dyes and Pigments (2019), doi: https://doi.org/10.1016/
j.dyepig.2019.04.044.
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ACCEPTED MANUSCRIPT

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Multi-photon Properties in Various Condensed Phases of Dendritic
Chromophores Derived from Carbazole and Indenoquioxaline
Units: Synthesis and Characterization
Tzu-Chau Lin,* a,b Wei Chien,a Shu-Wen Dai,c Hao-Wu Lin,*c and Yueh-Ching Liua
aPhotonic Materials Research Laboratory, Department of Chemistry, National Central
University, Jhong-Li District, Taoyuan City 32001, Taiwan. E-mail: tclin@ncu.edu.tw
bResearch Center of New Generation Light Driven Photovoltaic Module, National Central
University, Jhong-Li District, Taoyuan City 32001, Taiwan.
cDepartment of Materials Science and Engineering, National Tsing Hua University
Hsinchu 30013, Taiwan. E-mail: hwlin@mx.nthu.edu.tw
Abstract
We have used functionalized carbazoles and indenoquonoxalines as the main building
units and enthynyl groups as the π-linkages to construct two novel dendritic fluorophores
and studied their degenerate multi-photon absorption properties in both the solution phase
and the neat-film state within femtosecond and nanosecond regions. In our experiments,
these model compounds are found to manifest strong and widely dispersed two-photon
absorption as well as effective power-limiting properties against ultra-short laser pulses in
the near-IR region. In addition, both chromophores exhibit medium to strong
three-photon-induced fluorescence, indicating such scaffold may serve as a reference
structural motif for the development of three-photon materials.
Keywords: Two-photon absorption, three-photon absorption, Sonogashira reaction,
carbazole, indenoqunoxaline.
1. Introduction
Conjugated molecules that exhibit strong two-photon absorption (2PA) property have
drawn much attention in the past two decades owing to their potentiality for many
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promising applications in photonics and biophotonics such as optical power-limiting,
frequency up-converted lasing, optical data storage, nondestructive bio-imaging, and
two-photon photodynamic therapy.[1-5] During the searching course of highly efficient
2PA materials, enormous efforts have being made in exploring the knowledge of 2PA
molecular design and it is concluded that molecular 2PA can be affected by the
combination of several structural parameters including efficiency of the intramolecular
charge-transfer, effective size of the π-system and dimensionality of the molecule.[6-12]
Among the studied molecular architectures, branched chromophores have been
demonstrated to simultaneously possess strong multi-photon absorption and wide spectral
window of linear transparency[13, 14] and such a feature is particularly favorable for the
2PA-based broadband optical-limiting applications. In addition, it has been posited that the
2PA cross section (δ)-fluorescence quantum yield (ΦF) product (i.e. δΦF) or the ratio of
this product against photo-degradation quantum yield can be improved through rational
optimization of branched structures, which are vitriol requirements for the 2PA-based
imaging technologies.[1] Furthermore, branched scaffold provides an effective access for
the material chemists to incorporate 2PA-promoting parameters with various other desired
characteristics for specific purposes.
While much more attention was paid for the development of two-photon materials and
technologies, comparatively fewer efforts were made in the systematic investigation of
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organic materials that manifest strong three-photon absorption (3PA). Based on the
multi-photon absorption theory, any medium that exhibits 2PA can be expected to possess
detectable 3PA if appropriate experimental protocols are adopted. From the viewpoint of
application, 3PA process is expected to provide more benefits for bio-imaging applications
since near-infrared light with longer wavelength can be used and the light losses due to
scattering as well as linear absorption within the living organism will be greatly reduced.
On the other hand, a superior spatial confinement can be achieved because of the intrinsic
cubic dependence of a 3PA process on the local optical intensity, which subsequently
enhances the contrast and spatial resolution in the imaging-related applications. Besides,
under the same level of nonlinear transmission this higher order nonlinear absorption
process can offer promoted optical-limiting performance over broader spectral region. [15]
Following our continuous efforts in exploring new strategies for the molecular design of
highly efficient 2PA materials, we have focused our efforts on developing organic
chromophores with branched or dendritic scaffolds using various heterocyclics as the
building units and retrieving the structural parameters that may have either beneficial or
adverse impacts on their 2PA properties. In this paper, we present the synthesis and
2PA-related properties in both solution and neat-film forms of two newly synthesized
dendritic chromophores derived from carbazole and indenoquinoxaline moieties. In
addition, the effective 3PA properties of these model chromophores were also investigated
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within the spectral range of 1100-1500 nm using our previously reported experimental
condition in nanosecond regime, in order to explore the feasibility of such experimental
protocol and the molecular design for the 3PA materials.
2. Results and discussion
2.1 Molecular design and syntheses of the model chromophores
This model compound set contains two structural analogues as illustrated in Figure 1. We
have utilized a carbazole unit as the central ramification core, which is bonded to either
two or four peripheral lobes through ethynyl linkages to form model compound 1 and 2,
respectively. For compound 1, the peripheral branches are connected at C3 and C6
whereas for compound 2, the four branches are attached at C1, C3, C6, and C8 of the
central carbazole. Both diphenylaminocarbazole and indenoquinoxaline units are selected
as the main building blocks to construct these novel outward branches. It is well-known
that carbazole unit has been extensively utilized to construct various organic structures (i.e.
small molecules, polymers, and copolymers) for electronic, optoelectronic and photonic
applications including light-emitting diodes,[16] dye-sensitized solar cells,[17,18]
photorefractive materials,[19] and fluorescent sensors.[20-22] In addition to these
investigations, we have noticed that many carbazole-based small molecules were designed
and synthesized for the study of their multi-photon absorption properties,[23-27] but in
contrast, comparatively fewer carbazole-containing dendritic molecules[28, 29] were
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made for such study. Therefore, we believe that it is worthy to deepen our knowledge
about the nonlinear absorption behaviors of multi-branched or dendritic model structures
built by carbazole units. Our original attempt for the molecular design is to combine
various fused heterocyclic rings to form multi-branched polyarenes so that the final model
structures can be expected to exhibit more polarizable characters compared to their
all-carbon analogues and such feature is important for the enhancement of molecular
multi-photon activities. The synthetic procedures for the key components and the designed
model chromophores are depicted in Schemes 1 and 2. As shown in Scheme 1, the
commercialized 9H-carbazole (3) was utilized as the prime starting material to prepare
appropriately 3,6-difunctionalized and 1,3,6,8-tetrafunctionalized carbazoles (i.e.
compounds 7 and 8) as the major synthons for the π-centers of these model chromophores
through consecutive functional group transformation. On the other hand, since it is
necessary to prepare the corresponding diketone (i.e. compound 15) and diamine (i.e.
compound 16) for the synthesis of quinoxalinoid branch units, we have started from
4,4-dibromo-1,1-biphenyl (9) and performed nitration and triphenylphosphine-catalyzed
ring closure reaction in sequence to accomplish the desired 2,7-dibromo-9H-carbazole (11)
in the overall yield of 70%. Followed by the alkylation, amination, Pd-catalyzed
decarboxylative coupling reaction, and oxidation, compound 15 can be obtained in an
acceptable overall yield of 20% (from 11, four steps). Compound 15 was then coupled
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with previously reported diamine (16)[11] to form the key quinoxalinoid precursor 17 in
the yield of 86%. The same synthetic protocol used to transform the bromo functional
groups of compound 5 to the ethynyl groups of compound 7 was also applied to
compound 17 for the preparation of compound 19, another important quinoxalinoid
precursor for the synthesis of targeted chromophores. Finally, the model compounds 1 and
2 were accomplished through a 2- and a 4-fold Pd-catalyzed Sonogashira coupling using
the corresponding reactants and were obtained in the yields of 31% and 43%, respectively
(See Scheme 2). Interestingly, the obtained higher yield of the final Sonogashira coupling
for the preparation of compound 2 is contrary to our original expectation and we have
conjectured that both the electronic nature and molecular size of the synthon units that
bear either terminal alkyne (i.e. compounds 7 and 19) and bromo (i.e. compounds 8 and 17)
functional groups may play important roles to affect their reactivities in this final
Sonogashira reaction and lead to such results. All of the key intermediates and the final
model chromophores were thoroughly purified and the structures were determined by 1H
NMR, 13C NMR, and HRMS. The detailed syntheses for the preparation of the
aforementioned precursors and the targeted model fluorphores are described in the
Experimental section.
2.2 Optical properties characterization
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2.2.1 Linear absorption and fluorescence properties
Linear absorption (or one-photon absorption, 1PA) and fluorescence spectra of the studied
compounds in solution phase are shown in Fig 2. These chromophores exhibit intense
linear absorption in the UV-Vis region with their lowest-energy peaks located at 436 nm (
ε
~9.59×104 cm−1M−1) and 448 nm ( ~2.45×105 cm−1M−1), respectively. Strong
ε
yellow-green color of fluorescence from these two model compounds can be observed
under the irradiation of UV light and their fluorescence spectra in toluene are shown in the
inset of Fig. 2. All the photophysical data are collected in Table 1.
2.2.2 Two-photon-excited fluorescence properties in the femtosecond regime
2PA-induced fluorescence properties of these two chromophores were studied in the
femtosecond regime and the results are shown in Fig. 3. In these experiments, a
mode-locked wavelength-tunable Ti:Sapphire laser (Chameleon Ultra II, Coherent) was
employed to deliver ~140 fs pulses with the repetition rate of 80 MHz and the beam
diameter of 2 mm. The geometry of the optical setup for this experiment was carefully
aligned to ensure that only the emission from the front surface of the sample was collected,
which can minimize the inevitable inner filtering effect. The intensity of the excitation
beam was also judiciously regulated to avoid the saturation of absorption and
photodegradation. The same laser system and optical setup was also used for the
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characterization of 2PA-related properties of the spin-coated neat-film prepared from
compound 2 (vide infra).
In Fig 3(a), it is noted that the measured 2PA-induced emission spectrum for each model
chromophore is basically identical to its corresponding 1PA-induced fluorescence spectra
in the sense of the band shape and position (See the inset of Fig. 2), conveying that for
each studied sample the observed radiative relaxations are from the same final emitting
excited-states regardless of the excitation processes. A 2PA process is borne out to be the
main cause for the measured up-converted emission since the power-squared dependence
of the 2PA-induced fluorescence intensity on the excitation intensity was observed in all
cases as shown in the Figs. 3(b) and 3(c).
The degenerate 2PA spectra of the studied compounds were probed from 680 nm to 1080
nm by two-photon-excited fluorescence (2PEF) technique[30] in the femtosecond regime
as illustrated in Fig. 3(d). Both model chromophores exhibit strong two-photon activities
within the most part of the investigated spectral region with ascending magnitude of the
overall 2PA from compound 1 to compound 2. It is noticed that there is an observable
difference between the 2PA bands of these two compounds, that is, compound 1 possesses
a single local 2PA maximum at 770 nm (δ2~1950 GM) whereas compound 2 manifests
multiple local 2PA maxima at 760 nm (δ2~6100 GM), 830 nm (δ2~2200 GM), 890 nm
(δ2~1600 GM), and 930 nm (δ2~1300 GM), respectively.
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From the measured one- and two-photon-related photophysical properties of the studied
model compounds, some features are worthy to be discussed:
(1) The measured linear absorption spectra (Fig. 2) have revealed that both
compounds 1 and 2 exhibit multi-maximum linear absorption bands covering virtually
identical spectral region in the UV-Visible. Also, it is interesting to find that compound 1
shows descending molar absorption coefficients of its three local absorption maxima
toward the lower-energy end of the spectrum while compound 2 exhibits a completely
opposite tendency of it. The observed features indicate that expanding the π-conjugation
of compound 1 by attaching two additional quinoxalinoid branches at C1 and C8 positions
of the central carbazole to form compound 2 has enhanced the overall molecular linear
absorptivity and the extent of such promotion is more favorable for the lower-energy
absorption maxima. This behavior could be attributed to a fundamental difference in the
molecular structures between these two model compounds, that is, although compounds 1
and 2 are structural analogues, yet the structure of compound 1 is not exactly equal to half
a scaffold of compound 2 from the standpoint of molecular symmetry and the linking
topology between the central carbazole-core and the peripheries. Therefore, it is
reasonable to expect that these two model chromophores may possess distinct distribution
pattern (either in the sense of intensity, position, and the shape) of their linear absorption
spectra due to this intrinsic structural difference.
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(2) Compared to compound 1, chromophore 2 shows promoted molar absorption
coefficients and the maximal 2PA cross-section value as one can see from the measured
linear absorption and 2PA spectra. Such promotion can be attributed to the increased
number of the chromophoric units and the effective π-electrons while the molecular
structure expands from 1 to 2. It is also noted that the aforementioned structural expansion
exerts more extent of the enhancement on the molecular 2PA than on the linear
absorptivities. In other words, for these two compounds the ratio of their maximal 2PA
cross-section values (i.e. δ2max (2) /δ2max (1) ≈ 3.13 ) is larger than that of their molar
absorption
coefficients
of
the
lowest-energy
absorption
peaks
(i.e.
εmax (2at 448nm) / εmax (1at 436nm) ≈ 2.55 ). Such feature may imply the existence of a
2PA cooperative enhancement in this multi-branched molecular system. Although many
multi-branched molecules are reported to exhibit cooperative enhancement in their
two-photon activities, however, it is indeed a fact that not every multi-branched structure
possesses this kind of cooperative effect and since the general designing guide for such
structural effect is still lacking, our model compounds may be appropriate to serve as a
template for further study.
(3) The most accessible two-photon excited-states of these two chromophores
should be energetically higher than those of the lowest one-photon-allowed excited-states
since their major 2PA-bands are monotonically located at significantly shorter wavelength
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region compared to the corresponding wavelength positions of twice of their
2PA
max
1PA
lowest-energy linear absorption peaks (
i
.
e.
λ
< 2
λ
for each case). Besides, appreciable
max
two-photon activities aside from the main 2PA-band were observed at wavelengths that
energetically correspond to the spectral positions where these dye molecules exhibit strong
1PA as well. All the above-mentioned features imply that although the 1PA and 2PA
processes occurred within the studied chromophore system have followed different
selection rules, there are many excited states of these model dye molecules accessible by
both one-photon and two-photon transitions energetically.
(4) Using compound 1 as a reference point, the mode of structural expansion
adopted on this compound has rendered not only an overall elevated molecular 2PA but
also a broadened 2PA band as one can see from the measured 2PA spectra of compounds 1
and 2 in Fig. 3(d). This result indicates that these newly developed carbazole-containing
indenoquinoxalinoid peripheries are beneficial units for the construction of highly active
two-photon chromophores as long as they are incorporated appropriately. Moreover, any
materials that possess widely distributed and strong 2PA may be useful for broadband
optical power-limiting applications.
2.2.3 Optical power-limiting in femtosecond regime
The quadratic dependence of 2PA on the input light intensity is the essential intrinsic
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property that makes 2PA-materials to possess intensity-dependent transparency against
incident light, which is applicable in optical power-limiting applications. With the
increasing availability of hazardous light source especially those wavelength-tunable
ultrashort laser systems, the need for optical power-limiters that work in wide spectral
region with agile response are consequently very desirable. Since chromophore 2
manifests intense 2PA across a fairly wide spectral range, this compound is suitable to be
as a representative for the demonstration of 2PA-based optical power-limiting property
against femtosecond pulses. Figure 4(a) shows the measured data (in open triangle) of the
nonlinear transmittance (Ti) versus input laser power at ~800 nm. It can be seen from
Figure 4(a) that the intensity-dependent nonlinear transmission of the sample dropped
from ~0.95 to ~0.42 as the incident intensity elevated from ~37.5 mW to ~1055 mW. The
solid-line in Figure 4(a) represents the theoretical curve predicted by the basic 2PA
theory[31, 32] using
β = 1.7 cm/GW (2PA coefficient of the sample solution) as the best
fitting parameter. Based on the same set of data, Figure 4(b) illustrates an alternative way
to conceptualize this optical-control behavior as transmitted intensity is plotted against
input intensity. In this figure the theoretical fitting curve is presented by solid-line using
the same fitting parameter of
β = 1.7 cm/GW and the diagonal dot-line represents the
behavior for a medium without nonlinear absorption for comparison. It is noted from this
measured input-output curve (open circles) that the transmitted intensity starts to be
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suppressed at low pumping power, and such suppression rapidly approaches larger values
as the excitation power levels up. In addition, the 2PA cross-section value of this model
compound can be calculated to be ~2340 GM at 800 nm based on the performed
optical-power-limiting experiment, which is in good agreement with the result obtained
from 2PEF method and this verifies that 2PA is main cause for the observed
optical-control and upconverted emission behaviors in this chromophore system.
3. Two-photon properties of the neat-film fabricated from Compound 2
From the standpoint of application, it is important to gain knowledge about the optical
properties of the developed 2PA chromophores especially in their solid states in order to
further explore the applicability of these compounds for solid-state optical devices. As a
starting point, we tentatively investigated the two-photon properties of a spin-coated
neat-film prepared from compound 2 in the femtosecond regime based on 2PEF technique.
The fabrication method and the basic photophysical data of the prepared neat-film are
detailed in Supporting Information and summarized in Table 2, respectively. Figure 5
illustrates the normalized spectrum of two-photon excitation efficiency of the neat-film.
One can see that although the spectral position of the major 2PA excitation efficiency band
of the neat-film is roughly in good agreement with that of the measured 2PA spectrum of
the solution, a notable shape difference between these two measured curves particularly
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from 780 nm to 1000 nm is observed. We postulate that this behavior could be originated
from the difference of the intramolecular interaction of this chromophore in its two
distinct physical states because the significantly shorter intramolecular distance in solid
state (i.e. neat-film case) may affect the molecular conformation and results in altered
effective size of π-domain and charge-transfer efficiency and hence lead to partially
altered spectral behavior. Nevertheless, it is a desirable property for the applications since
a wider spectral window of 2PA activities is covered and the fabricated solid state device
will consequently possess a broader active working range. In addition, the square
dependence of the emission intensity on the excitation intensity (See Figure S3 has
verified that a 2PA process is mainly responsible for the observed fluorescence. We wish
to point out that it is important to evaluate the absolute two-photon strength of the
neat-film within certain spectral range since it is an essential parameter for the future
device design and fabrication. The development of such measurement is currently
underway in our laboratory and will be reported in due course.
4. Effective three-photon properties in nanosecond regime
One can imagine that 3PA would be much more difficult to be observed than 2PA since in
theory the magnitude of 3PA is significantly smaller than that of 2PA for a given
compound. Nevertheless, it is reasonable to select chromophores with intense 2PA as
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model subjects for three-photon excitation (3PE) studies as such molecules have been
experimentally validated to possess strong 3rd-order nonlinearity and can be anticipated to
exhibit detectable higher-order nonlinearities. Moreover, it should be noted that the
selection of appropriate range of excitation wavelength is important for achieving 3PE. We
have previously demonstrated that under certain experimental condition some useful
information regarding two- and three-photon excitation properties such as the order of
absorption process (OAP) across a specific spectral region of a selected material can be
retrieved by using a nanosecond laser.[33] At the same time, we are also curious about
whether our experimental condition remains valid for other types of molecules. Therefore,
we intend to apply our experimental protocol on this newly developed
carbazole-containing system and explore the applicability of this method. In this
investigation, the same experimental condition as previously reported by us has been
followed to probe the three-photon-excited fluorescence (3PEF) intensities and OAP of
these two compounds within the corresponding spectral range and the results are presented
in Fig. 6.
When excited at 1400 nm, compound 2 exhibits an intensive green color emission with
virtually identical spectrum of 2PA-induced fluorescence (see Fig. 3(a) and Fig. 6(a)).
Since the excitation wavelength is significantly far away from the major 2PA band of this
model chromophore and the observed emission intensity possesses a cubic-dependence on
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the input intensity, it is corroborated that the measured fluorescence is induced by a 3PA
process. The dispersion of three-photon-excitation efficiency of compounds 1 and 2 are
presented in Fig. 6(b) and it is noted that in the studied spectral region these two
compounds exhibit very similar dispersion pattern of their excitation efficiency with
compound 2 manifests a saliently higher overall efficiency.
As illustrated in Fig. 6(c), the order of the absorption process (OAP) of compound 2 as a
function of wavelength (i.e. OAP spectrum) can be delineated by monitoring the
power-dependence of the up-converted emission intensity on the excitation intensity
across different wavelengths. Agree to our anticipation, three major distinct OAP
behaviors were found in the obtained spectrum and can be analyzed separately. In the
region from 1160 to 1400 nm, the observed third-order dependence implies that all the
transitions in this region are induced by 3PA. When the excitation wavelengths were tuned
hyperchromically toward spectral region of 1000-1100 nm, intermediate values of OAP
(i.e. ≈2.3-2.7) were obtained, indicating that 2PA and 3PA are coexistent and competing
with each other within such spectral region. Therefore, for the excitation wavelengths
which are close to the 1000 nm end, 2PA process would be dominant over 3PA because
comparatively lower intensity is required to achieve 2PA and the obtained OAP is closer to
2 whereas if the excitation wavelengths near 1100 nm are utilized, the rising 3PA becomes
competitive so that the obtained OAP value is closer to 3. Finally, in highly two-photon
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active spectral region (i.e. 760-950 nm) a quadratic dependence was held, which is in good
agreement with the results measured by femtosecond laser.
Since there is no apparent distortion of the measured fluorescence properties based on the
results shown in Fig. 6, it may suggest that our experimental protocol by using nanosecond
laser to probe 3PA-induced fluorescence properties is suitable for different molecular
systems.
5. Conclusions
In summary, two new model chromophores using acetylene groups to connect a central
carbazole core with either two or four peripheral diphenylaminocarbazole-substituted
indenoquinoxalinoids were constructed and investigated for their multi-photon properties in
both solution and neat-film states. These two model compounds are found to possess strong
and wide dispersed two-photon activities in the near-IR region. The larger congener with
four outward branches (i.e. compound 2) was also demonstrated to exhibit efficient
power-supressing property against femtosecond laser pulses at 800 nm. On the other hand,
we have experimentally verified that our previously reported experimental protocol for
studying three-photon-induced fluorescence properties and the order of absorption process
(OAP) using nanosecond pulses is also applied to this model chromophore system, which
may suggest that our experimental condition is reliable and can be commonly utilized for
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such characterization. Besides, both chromophores are found to exhibit salient and
detectable three-photon-induced fluorescence, indicating the designed scaffold may serve
as a reference structural motif for the design of efficient three-photon materials.
6. Experimental section
6.1 General
All the commercialized reagents for the preparation of the intermediates and targeted
chromophores were purchased either from Acros Organics or Alfa Aesar and were used as
1
received, unless stated otherwise. THF was distilled from sodium benzophenone ketyl. H
13
NMR and C NMR spectra were recorded by a 300 MHz spectrometer and referenced to
TMS or residual CHCl3. The numbering of carbon and hydrogen atoms on each
intermediate and the final chromophore for the NMR signal assignment are systematized
and illustrated in the ESI. High-resolution mass spectroscopy (HRMS) was conducted by
using a Waters LCT ESI-TOF mass spectrometer. MALDI-TOF MS spectrum was obtained
on a Voyager DE-PRO mass spectrometer (Applied Biosystem, Houston, USA).
6.2 Photophysical Methods and film fabrication
Linear optical properties including linear (one-photon) absorption spectra, fluorescence
spectra, fluorescence quantum yields, and fluorescence lifetimes of the studied model
compounds were recorded by the corresponding spectrometers. Two- and
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three-photon-related properties were measured using either a Ti:sapphire oscillator or a
regenerative amplifier system as the probing tool. The detailed experimental conditions
and the configuration of optical set-ups for nonlinear optical property investigations are
described in the ESI.
6.3 Synthesis
The previously reported procedures were followed for the synthesis of compound 16 (See
Scheme 1) [11] and the preparation of other key precursors and the final model
chromophores are described in detail as the following:
6.3.1
9-Hexyl-9H-carbazole (4)
To a mixture of compound 3 (1.27 g, 0.07 mol) in THF (13 mL) was added KI (0.01 g,
0.08 mmol), sodium tert-butoxide (2.9 g, 0.030 mol), and 1-bromohexane (1.40 mL, 0.009
mol) stirred at 80 °C for 9 hours. Then the mixture was added pyridine (1 ml) and refluxed
for 30 min. The above solution was cooled down to r.t. and quenched with 1N HCl to
neutral then extracted with ethyl acetate (50 ml × 3) and then dried over MgSO4(S). After
filtration and removal the solvent, the crude product was purified with column
chromatography on silica gel using hexane as eluent to afford the white solid with yield of
1
84.9 % (1.62 g). H NMR (300 MHz, CDCl3)
δ: 8.05-8.03 (d,
J
= 7.5Hz, 2H, H5),
7.41-7.29 (m, 4H, H2, H3), 7.19-7.14 (m, 2H, H4), 4.14-4.10 (m, 2H, Hf), 1.76-1.72 (m, 2H,
He), 1.26-1.17 (m, 6H, Hb, Hc, Hd), 0.82-0.76 (m, 3H, Ha); 13C NMR (75 MHz, CDCl3)
δ:
140.35 (C1), 125.48 (C3), 122.75 (C6), 120.25 (C5), 118.62 (C4), 108.58 (C2), 42.89 (Cf),
31.51 (Ce), 28.83 (Cd), 26.88 (Cc), 22.49 (Cb), 13.97 (Ca); HRMS-EI (m/z): [M]+ calcd for
C18H21N, 251.1674; found, 251.1673.
6.3.2
3,6-Dibromo-9-hexyl-9H-carbazole (5)
A mixture of compound 4 (1.22 g‚ 4.84 mmol) and TBABr3 (5.12 g‚ 10.63 mmol) in
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CH2Cl2 (49 mL) and MeOH (20 mL) was stirred at r.t. for 2 hours. Then the saturated
NaHSO3(aq) (60 ml) was added into the reaction mixture and the resulting solution was
extracted with dichloromethane (50 ml × 3). The organic layer was collected and dried
over MgSO4(S). After filtration and removal of the solvent, the crude solid product was
collected and recrystallized from methanol. The purified product was obtained as
green-brownish powder with yield of 74.7% (1.47 g). 1H NMR (300 MHz, CDCl3)
δ:
8.14-8.13 (d, = 1.8Hz, 2H, H5), 7.56-7.53 (dd, 1 = 8.4Hz, 2 = 1.8Hz, 2H, H3), 7.28-7.25
J
J
J
(d,
J
= 8.1Hz, 2H, H12), 4.26-4.21 (m, 2H, Hf), 1.84-1.80 (m, 2H, He), 1.33-1.26 (m, 6H,
13
Hb, Hc, Hd), 0.88-0.83 (m, 3H, Ha); C NMR (75 MHz, CDCl3)
δ: 139.26 (C1), 128.96
(C5), 123.39 (C6), 123.21 (C3), 111.89 (C4), 110.35 (C2), 43.31 (Cf), 31.47 (Ce), 28.79 (Cd),
26.85 (Cc), 22.48 (Cb), 13.95 (Ca); MALDI-TOF (m/z): [M]+ calcd for C18H19Br2N,
409.1639; found, 409.1655.
9-Hexyl-3,6-bis((trimethylsilyl)ethynyl)-9H-carbazole (6)
To a solution of compound 5 (1.47 g, 3.59 mmol) in THF (12 mL) was added
PdCl2(PPh3)2 (0.31 g, 0.43 mmol), CuI (0.137 g, 7.18 mmol), trimethylsilyl acetylene
(1.06 g, 10.78 mmol) and i-Pr2NH (3 mL) and the whole system was stirred at 90°C under
N2 for 24 hours. After cooling to the r.t., the above solution was then extracted with
dichloromethane (30 mL × 3). The organic layer was collected and dried over MgSO4(s).
After filtration and removal of the solvent, the crude product was purified through column
chromatography on silica gel using hexane as the eluent to give the final product as
pale-yellow oil with yield of 62.9% (1 g). 1H NMR (300 MHz, CDCl3)
δ: 8.23-8.22 (d,
J =
0.9Hz, 2H, H5), 7.60-7.57 (dd, J1 = 8.4Hz, J2 = 1.0Hz, 2H, H3), 7.27-7.24 (d,
J
= 8.4Hz,
1H, H2), 4.19-4.15 (m, 2H, Hf), 1.82-1.78 (m, 2H, He), 1.29 (br, m, 6H, Hb, Hc, Hd),
13
0.90-0.86 (m, 3H, Ha), 0.36 (s, 18H, hydrogens on the TMS group); C NMR (75 MHz,
CDCl3) δ: 140.40 (C1), 129.89 (C5), 124.55 (C3), 122.20 (C6), 113.69 (C4), 108.70 (C2),
106.40 (sp-carbon), 91.94 (sp-carbon), 43.12 (Cf), 31.41 (Ce), 28.76 (Cd), 26.77 (Cc),
22.45 (Cb),13.91 (Ca), 0.15 (methyl carbons on the TMS group).
6.3.3
3,6-Diethynyl-9-hexyl-9H-carbazole (7)
To a solution of compound 6 (1g, 2.44mmol) in THF/MeOH (10 mL/5 mL) was added
KOH (1 g, 2.44 mmol) and H2O (2 mL) and the mixture was stirred at r.t. under N2 for 6
hours. The above solution was then extracted with dichloromethane (30 mL × 3). The
organic layer was collected and dried over MgSO4(s). After filtration and removal of the
solvent, the crude product was purified through column chromatography on silica gel
using hexane as the eluent to give the final product as pale-yellow oil with yield of 86%
1
(0.37 g). H NMR (300 MHz, CDCl3)
δ: 8.14 (s, 2H, H5), 7.56-7.52 (dd, J1 = 8.4Hz, J2
=
1.5Hz, 2H, H3), 7.24-7.21 (d,
J = 8.7Hz, 1H, H2), 4.14-4.09 (m, 2H, Hf), 3.06 (s, 2H,
sp-hydrogen), 1.76-1.72 (m, 2H, He), 1.24 (br, m, 6H, Hb, Hc, Hd), 0.84-0.80 (m, 3H, Ha);
- 20 -

ACCEPTED MANUSCRIPT
13C NMR (75 MHz, CDCl3)
δ: 140.51 (C1), 130.01 (C5), 124.62 (C3), 122.12 (C6), 112.60
(C4), 108.83 (C2), 84.73 (sp-carbon), 75.43 (sp-carbon), 43.13 (Cf), 31.40 (Ce), 28.76 (Cd),
26.78 (Cc), 22.43 (Cb), 13.90 (Ca).
6.3.4
1,3,6,8-Tetrabromo-9-hexyl-9H-carbazole (8)
A solution composed of compound 4 (0.4 g‚ 1.57 mmol) and NBS (4.21 g‚ 23.65 mmol) in
THF (20 mL) was stirred at r.t. for 24 hours. Then the saturated NaHSO3(aq) (20 ml) was
added into the reaction mixture and the resulting solution was extracted with
dichloromethane (50 ml × 3). After filtration, the organic solvent was removed by rotary
evaporation to afford crude product which was then was purified by column
chromatography on silica gel using hexane as eluent. The target compound was obtained
1
as white solid with yield of 27.9 % (0.25 g). H NMR ( 300 MHz, CDCl3)
δ: 8.018-8.011
(d,
J
= 2.1Hz, 2H, H5), 7.77-7.76 (d,
J
= 1.8Hz, 2H, H3), 5.09-5.03 (m, 2H, Hf), 1.79-1.71
13
(m, 2H, He), 1.35-1.25 (m, 6H, Hb, Hc, Hd), 0.89-0.75 (m, 3H, Ha); C NMR (75 MHz,
CDCl3) δ: 136.64 (C1), 134.82 (C3), 125.88 (C6), 121.88 (C5), 112.64 (C4), 103.92 (C2),
44.62 (Cf), 31.83 (Ce), 31.35 (Cd), 25.73 (Cc), 22.57 (Cb), 13.94 (Ca); MALDI-TOF (m/z):
[M]+ calcd for C18H17Br4N, 566.9550; found, 566.9574.
6.3.5
4,4'-Dibromo-2-nitro-1,1'-biphenyl (10)
To a solution of compound 9 (24 g, 76.9 mmol) in acetic acid (360 ml) was added HNO3
(112.78 ml, 2.70 mol) dropwisely. The resulting mixture was stirred at 100°C for 6 hours.
The reaction mixture was then extracted with dichloromethane (50 ml × 3) and the organic
layer was dried over MgSO4(S). After filtration and removal of the solvent, the crude
product was purified by column chromatography on silica gel using
dichloromethane-hexane (1:10) as the eluent to give the final purified product as yellow
1
powder with yield of 87.6 % (24.13 g). H NMR ( 300 MHz, CDCl3)
δ
: 8.02-8.01 (d,
= 8.7Hz,
= 8.4Hz, 2H, H8, H12); 13C
: 149.20 (C5), 135.52 (C2), 135.25 (C4), 134.07 (C7), 132.98 (C3),
J =
2.1Hz, 1H, H6), 7.76-7.73 (dd, J1 = 8.4Hz, J2 = 2.1Hz, 1H, H2), 7.56-7.53 (d,
2H, H9, H11), 7.29-7.26 (d, = 8.1Hz, 1H, H3), 7.16-7.13 (d,
NMR (75 MHz, CDCl3)
J
J
J
δ
131.97 (C8, C12), 129.37 (C9, C11), 127.21 (C6), 123.02 (C10), 121.79 (C1); HRMS-EI (m/z):
[M]+ calcd for C12H7Br2NO2, 354.8844; found 354.8850 [(79Br)(79Br)M]+, 356.8821
[(79Br)(81Br)M]+, 358.8803 [(81Br)(81Br)M]+.
6.3.6
2,7-Dibromo-9H-carbazole (11)
A solution of compound 10 (24.13 g, 67.54 mmol) and PPh3 (44.27 g, 168.88 mmol) in
- 21 -

ACCEPTED MANUSCRIPT
o
-dichlorobenzene (120 ml) was stirred at 180°C for 3 hours. After cooled down to r.t., the
reaction mixture was purified by column chromatography on silica gel using
dichloromethane-hexane (1:5) as the eluent to give the final purified product as white-off
1
solids with yield of 82.5% (18.09 g). H NMR (300 MHz, (CD3)2SO)
δ
: 11.55 (s, 1H,
= 1.5Hz, 2H, H2), 7.37-7.34 (dd, J1
2 = 1.8Hz, 2H, H4); 13C NMR (75 MHz, (CD3)2SO)
: 141.74 (C1), 123.05 (C4),
-NH), 8.13-8.10 (d,
= 8.4Hz,
J = 8.4Hz, 2H, H5), 7.75-7.74 (d, J
J
δ
122.89 (C5), 121.95 (C6), 119.66 (C3), 114.81 (C2); HRMS-EI (m/z): [M]+ calcd for
C12H7Br2N, 322.8945; found 322.8938 [(79Br)(79Br)M]+, 324.8950 [(79Br)(81Br)M]+,
326.8954 [(81Br)(81Br)M]+.
6.3.7
2,7-Hibromo-9-hexyl-9H-carbazole (12)
To a mixture of compound 11 (18.09 g, 0.053 mol) in THF (74 mL) was added KI (0.094 g,
0.53 mmol), sodium tert-butoxide (21.37 g, 0.221 mol) and 1-bromohexane (10.2 mL,
0.074 mole). The resulting solution was stirred at 80°C for 9 hours. Then pyridine (7.4 ml)
was added and the whole system was refluxed for 30 min. The above solution was
quenched with 1N HCl to neutral and then extracted with ethyl acetate (50 ml × 3). The
organic layer was collected and dried over MgSO4(S). After filtration and removal of the
solvent, the crude product was purified with column chromatography on silica gel using
hexane as eluent to afford the white solid with yield of 87.3 % (19.85 g). 1H NMR (300
MHz, CDCl3)
7.30-7.27 (dd, J1 = 8.1Hz, J2 = 1.5Hz, 2H, H4), 4.10-4.05 (m, 2H, Hf), 1.79-1.74 (m, 2H,
He), 1.29 (m, 6H, Hb, Hc, Hd), 0.88-0.83 (m, 3H, Ha); 13C NMR (75 MHz, CDCl3)
δ: 7.81-7.78 (d, J = 8.4Hz, 2H, H5), 7.467-7.462 (d, J = 1.5Hz, 2H, H2),
δ:
141.24 (C1), 122.43 (C4), 121.37 (C5), 121.18 (C6), 119.62 (C3), 111.89 (C2), 43.24 (Cf),
31.44 (Ce), 28.69 (Cd), 26.79 (Cc), 22.50 (Cb), 13.96 (Ca); MALDI-TOF (m/z): [M]+ calcd
for C18H19Br2N, 409.1639; found, 409.1652.
6.3.8
7-Bromo-9-hexyl-N,N-diphenyl-9H-carbazol-2-amine (13)
To a mixture of compound 12 (19.8 g, 48.36 mmol) and diphenylamine (8.17 g, 48.79
mmol) in toluene (98mL) was added BINAP (0.88 g, 1.43 mmol), Pd2(dba)3 (0.440 g,
0.485 mmol), sodium tert-butoxide (2.68 g, 27.84 mmol) and the resulting solution stirred
at 80°C under Ar atmosphere for 24 hours. After cooling to the r.t., H2O (100 mL) was
added to the reaction mixture which was then extracted with ethyl acetate and the organic
layer was dried over MgSO4(S). After filtration and removal of the solvent, the crude
product was purified through column chromatography on silica gel using hexane as eluent
to give the final purified product as pale-yellow oil with yield of 51.2% (12.36 g). 1H
NMR (300 MHz, CDCl3)
H13), 7.457-7.452 (d,
δ: 7.88-7.85 (d, J = 8.4Hz, 1H, H12), 7.82-7.79 (d, J = 8.1Hz, 1H,
J
= 1.5Hz, 1H, H15), 7.29-7.25 (m, 5H, H2, H9), 7.24-7.22 (m, 2H,
- 22 -

ACCEPTED MANUSCRIPT
H1), 7.15-7.14 (m, 1H, H8), 7.12-7.11 (m, 1H, H6), 7.07-6.98 (m, 4H, H3), 4.08-4.03 (m,
2H, Hf), 1.74-1.69 (m, 2H, He), 1.23-1.22 (m, 6H, Hb, Hc, Hd), 0.85-0.81 (m, 3H, Ha); 13C
NMR (75 MHz, CDCl3) δ: 148.10 (C4), 146.59 (C7), 141.66 (C5), 141.55 (C16), 129.14
(C2), 123.94 (C3), 122.54 (C1), 121.98 (C12), 121.83 (C14), 120.87 (C13), 118.31 (C10),
117.98 (C11), 117.71 (C9), 117.32 (C15), 111.49 (C8), 104.82 (C6), 42.88 (Cf), 31.40 (Ce),
28.63 (Cd), 26.68 (Cc), 22.40 (Cb), 13.96 (Ca); MALDI-TOF (m/z): [M]+ calcd for
C30H29BrN2, 496.1514; found, 496.1527.
6.3.9
7,7'-(Ethyne-1,2-diyl)bis(9-hexyl-N,N-diphenyl-9H-carbazol-2-amine) (14)
A mixture composed of compound 13 (12.36 g, 24.85 mmol), acetylenedicarboxylic acid
(1.416g, 12.42mmol), 1,4-bis(diphenylphosphino) butane (1.06 g, 2.46 mmol) and
PdCl2(PPh3)2 (0.0872 g, 0.12 mmol) in DMSO (30.7 mL) was stirred at 110°C under Ar
atmosphere for 8 hours. After cooling to the r.t., cold methanol (5 mL) and cold hexane (5
mL) was added to the reaction mixture and the whole system was stirred at 0°C for 30 min.
After filtration, the crude solid product was collected and recrystallized from methanol.
The purified product was obtained as yellow powder with yield of 68% (7.57 g). 1H NMR
(300 MHz, CDCl3) δ: 7.97-7.90 (m, 4H, H9, H12), 7.56 (s, 2H, H15), 7.44-7.42 (d, J =
8.1Hz, 2H, H13), 7.28-7.23 (m, 8H, H2), 7.16-7.14 (m, 8H, H3), 7.10-7.09 (m, 2H, H8),
7.04-6.95 (m, 6H, H1, H6), 4.16-4.11 (m, 4H, Hf), 1.79-1.75 (m, 4H, He), 1.26 (br, 12H, Hb,
Hc, Hd), 0.86-0.82 (m, 6H, Ha); 13C NMR (75 MHz, CDCl3)
δ: 148.17 (C4), 146.66 (C16),
142.26 (C7), 140.47 (C5), 129.16 (C2), 123.98 (C3), 122.88 (C11), 122.79 (C13), 122.55 (C1),
121.06 (C9), 119.61 (C12), 119.34 (C14), 118.34 (C10), 117.26 (C8), 111.64 (C15), 104.78
(C6), 90.46 (sp-carbon), 42.97 (Cf), 31.52 (Ce), 28.81 (Cd), 26.82 (Cc), 22.47 (Cb), 14.00
(Ca); MALDI-TOF (m/z): [M]+ calcd for C62H58N4, 858.4661; found, 858.4682.
6.3.10
1,2-Bis(7-(diphenylamino)-9-hexyl-9H-carbazol-2-yl)ethane-1,2-dione (15)
To a solution of compound 14 (7.57 g; 8.84 mmol) in CH2Cl2 (40mL) was added KMnO4
(5.61 g; 35.39 mmol), NaHCO3 (0.741 g; 8.84 mmol), Aliquat 336 (1.23 g), and H2O (20
mL) and the resulting solution was stirred at r.t. 18 hours before the addition of saturated
NaHSO3 (50 mL) and 1N HCl solutions. The above solution was then extracted with
dichloromethane (50 mL×3). The organic layer was collected and dried over MgSO4(s).
After filtration and removal of the solvent, the crude product was purified through column
chromatography on silica gel using dichloromethane-hexane (1:3) as the eluent to give the
final product as pale-orange powder with yield of 66.5% (5.24 g). 1H NMR (300 MHz,
CDCl3)
δ: 8.10 (s, 2H, H15), 8.01-7.98 (d,
J = 8.1Hz, 2H, H12), 7.93-7.91 (d, J = 8.7Hz, 2H,
H9), 7.79-7.76 (dd,
J
1 = 8.4Hz, 2 = 1.2Hz, 2H, H13), 7.30-7.23 (m, 8H, H2), 7.18-7.15 (m,
J
8H, H3), 7.07-7.02 (m, 6H, H1, H6), 6.99-6.96 (dd, J1 = 8.7Hz, J2 = 1.8Hz, 2H, H8),
- 23 -

ACCEPTED MANUSCRIPT
4.17-4.12 (m, 4H, Hf), 1.75-1.70 (m, 4H, He), 1.19 (br, m, 12H, Hb, Hc, Hd), 0.81-0.77 (m,
13
6H, Ha); C NMR (75 MHz, CDCl3)
δ: 195.66 (carbonyl carbon), 148.38 (C16), 147.79
(C4), 143.65 (C7), 140.30 (C11), 129.44 (C14), 129.28 (C2), 128.43 (C5), 124.60 (C3),
123.18 (C1), 122.04 (C12), 121.63 (C9), 119.45 (C8), 117.03 (C10), 116.92 (C13), 109.80
(C15), 103.54 (C6), 42.98 (Cf), 31.38 (Ce), 28.80 (Cd), 26.70 (Cc), 22.38 (Cb), 13.93 (Ca);
MALDI-TOF (m/z): [M]+ calcd for C62H58N4O2, 890.4559; found, 890.4583.
6.3.11
7,7'-(8-Bromo-10,10-dihexyl-10
diphenyl-9 -carbazol-2-amine) (17)
To a solution of compound 16 (3.15 g, 7.2 mmol) and compound 15 (5.24 g, 5.89 mmol) in
THF (20 ml) was added CH3COOH (2 mL). The resulting mixture was stirred at 80
H-indeno[1,2-g]quinoxaline-2,3-diyl)bis(9-hexyl-N,N-
H
℃
under Ar atmosphere for 12 hours. After cooling to the r.t., the reaction mixture was then
extracted with ethyl acetate (30 mL × 3). The organic layer was collected and dried over
MgSO4(s). After filtration and removal of the solvent, the crude product was purified
through column chromatography on silica gel using dichloromethane-hexane (1:3) as the
1
eluent to give the final product as yellow powder with yield of 86% (6.55 g). H NMR
(300 MHz, CDCl3)
δ: 8.45 (s, 1H, H8), 8.13 (s, 1H, H11), 7.97-7.93 (dd, J1 = 8.1Hz, J2
=
1.8Hz, 2H, H18), 7.89-7.86 (dd,
J
1 = 8.4Hz, 2 = 0.9Hz, 2H, H19), 7.78-7.75 (d, = 8.4Hz,
J
J
1H, H5), 7.58-7.53 (m, 3H, H2, H22), 7.48 (s, 2H, H16), 7.26-7.21 (m, 9H, H4, H28),
7.14-7.11 (m, 8H, H29), 7.02-6.93 (m, 10H, H23, H25, H27), 3.91-3.87 (m, 4H, Hf1),
2.15-2.04 (m, 4H, Hf), 1.32 (br, m, 4H, He1), 1.09-1.06 (m, 16H, Hc, Hd, Hd1, He),
0.95-0.94 (m, 8H, Hb1, Hc1), 0.78-0.73 (m, 16H, Ha1, Ha, Hb); 13C NMR (75 MHz, CDCl3)
δ: 154.07 (C13), 153.63 (C17), 153.54 (C17’), 152.86 (C14), 148.15 (C30), 146.55 (C10),
142.79 (C1), 142.29 (C9), 141.30 (C15), 141.21 (C15’), 140.31 (C7), 138.69 (C6), 136.00
(C24), 135.92 (C20), 132.46 (C12), 130.60 (C2), 129.11 (C28), 126.49 (C5), 123.96 (C29),
123.29 (C3), 123.05 (C26), 122.50 (C27), 121.15 (C4, C11), 120.93 (C8), 119.63 (C19, C22),
118.49 (C18), 118.17 (C21), 117.02 (C23), 110.58 (C16), 104.62 (C25), 55.46 (Cg), 42.69
(Cf1), 41.22 (Cf), 31.49 (Ce), 31.05 (Ce1), 29.64 (Cd), 28.37 (Cd1), 26.47 (Cc1), 23.91 (Cc),
22.53 (Cb), 22.34 (Cb1), 13.94 (Ca, Ca1); MALDI-TOF (m/z): [M]+ calcd for C87H89BrN6,
1296.6332; found,1296.6370.
6.3.12
7,7'-(10,10-Dihexyl-8-((trimethylsilyl)ethynyl)-10
H-indeno[1,2-g]quinoxaline-2,3-diyl
)bis(9-hexyl- -diphenyl-9 -carbazol-2-amine) (18)
N,
N
H
To a solution of compound 17 (3.2 g, 2.46 mmol) in THF (15 mL) was added
PdCl2(PPh3)2 (0.103 g, 0.147 mmol), CuI (0.047 g, 0.24 mmol), trimethylsilyl acetylene
(0.36 g, 3.7 mmol) and i-Pr2NH (3.82 mL) and the resulting soluton was stirred at 90°C
under N2 for 24 hours. After cooling to the r.t., the reaction mixture was then extracted
- 24 -

ACCEPTED MANUSCRIPT
with dichloromethane (30 mL × 3) and the organic layer was collected and dried over
MgSO4(s). After filtration and removal of the solvent, the crude product was further
purified through column chromatography on silica gel using THF-hexane (1:10) as the
1
eluent to give the final product as yellow powder with yield of 87.8% (2.83 g). H NMR
(300 MHz, CDCl3)
δ: 8.44 (s, 1H, H8), 8.11 (s, 1H, H11), 7.6-7.92 (dd, J1 = 7.8Hz, J2
=
2.1Hz, 2H, H18), 7.89-7.86 (dd,
J
1 = 8.4Hz, 2 = 8.4Hz, 2H, H23), 7.85-7.83 (d, = 8.4Hz,
J
J
1H, H5), 7.55-7.51 (m, 3H, H2, H19), 7.47 (s, 2H, H16), 7.26-7.21 (m, 9H, H4, H28),
7.13-7.11 (m, 8H, H29), 7.02-6.92 (m, 10H, H22, H25, H27), 3.92-3.86 (m, 4H, Hf1),
2.12-2.08 (m, 4H, Hf), 1.32 (br, m, 4H, He1), 1.11-1.04 (m, 16H, Hc, Hd, Hd1, He),
0.95-0.93 (m, 8H, Hb1, Hc1), 0.77-0.67 (m, 16H, Ha1, Ha, Hb) , 0.36 (s, 9H, hydrogens on
the TMS groups); 13C NMR (75 MHz, CDCl3)
δ: 154.01 (C13), 153.59 (C14), 153.47 (C1),
151.30 (C17), 148.16 (C30), 146.55 (C10), 143.15 (C9), 142.29 (C6), 141.37 (C7), 141.21
(C12), 140.31 (C15), 140.06 (C24), 136.06 (C20), 135.96 (C26), 131.53 (C2), 129.10 (C28),
126.55 (C4), 123.96 (C29), 123.28 (C3), 122.49 (C27), 122.38 (C11), 121.14 (C5), 120.96
(C8), 120.88 (C22), 119.61 (C19), 118.75 (C18), 118.19 (C21), 117.01 (C23), 110.60 (C16),
105.85 (C25), 104.62 (sp-carbon), 95.02 (sp-carbon), 55.23 (Cg), 42.69 (Cf1), 41.31 (Cf),
31.52 (Ce), 31.04 (Ce1), 29.69 (Cd), 28.36 (Cd1), 26.46 (Cc1), 23.91 (Cc), 22.54 (Cb), 22.33
(Cb1), 13.93 (Ca, Ca1), 0.01 (methyl carbons on the TMS group); MALDI-TOF (m/z): [M]+
calcd for C92H98N6Si, 1314.7622; found, 1314.7651.
6.3.13
7,7'-(8-Ethynyl-10,10-dihexyl-10
H-indeno[1,2-g]quinoxaline-2,3-diyl)bis(9-hexyl-N,N
-diphenyl-9 -carbazol-2-amine) (19)
H
To a solution of compound 18 (2.83 g, 2.15 mmol) in THF/MeOH (2 mL/7 mL) was
added KOH (0.48 g, 8.59 mmol) and H2O (2.67 mL) and the resulting mixture was stirred
at r.t. under N2 for 6 hours. The reaction solution was then extracted with dichloromethane
(30 mL × 3) and the organic layer was collected and dried over MgSO4(s). After filtration
and removal of the solvent, the crude product was purified through column
chromatography on silica gel using THF-hexane (1:10) as the eluent to give the final
1
product as yellow powder with yield of 91.5% (2.44 g). H NMR (300 MHz, CDCl3)
δ:
8.47 (s, 1H, H8), 8.14 (s, 1H, H11), 7.97-7.94 (dd, J1 = 8.1Hz, J2 = 2.1Hz, 2H, H18),
7.90-7.85 (m, 3H, H5, H23), 7.59-7.55 (m, 3H, H2, H19), 7.48 (s, 2H, H16), 7.26-7.20 (m,
9H, H4, H28), 7.14-7.11 (m, 8H, H29), 7.02-6.93 (m, 10H, H22, H25, H27), 3.91-3.87 (m, 4H,
Hf1), 3.18 (s, 2H, sp-hydrogen), 2.16-2.07 (m, 4H, Hf), 1.34-1.30 (m, 4H, He1), 1.11-1.05
(m, 16H, Hc, Hd, Hd1, He), 0.95-0.94 (m, 8H, Hb1, Hc1), 0.78-0.72 (m, 12H, Ha1, Ha),
13
0.70-0.67 (m, 4H, Hb); C NMR (75 MHz, CDCl3)
δ: 154.05 (C13), 153.67 (C14), 153.40
(C1), 151.40 (C17), 148.15 (C30), 146.55 (C10), 143.00 (C9), 142.29 (C6), 141.40 (C7),
141.18 (C12), 140.32 (C15), 136.03 (C24), 135.93 (C20), 131.56 (C2), 129.10 (C28), 126.82
(C4, C11), 123.96 (C29), 123.30 (C26), 122.49 (C27), 122.16 (C3), 121.14 (C5), 120.96 (C8),
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119.62 (C22), 118.86 (C18), 118.18 (C21), 117.02 (C23), 110.59 (C16), 104.61 (C25), 84.35
(sp-carbon), 77.92 (sp-carbon), 55.22 (Cg), 42.68 (Cf1), 41.25 (Cf), 31.49 (Ce), 31.04 (Ce1),
29.66 (Cd), 28.36 (Cd1), 26.46 (Cc1), 23.91 (Cc), 22.52 (Cb), 22.33 (Cb1), 13.93 (Ca, Ca1);
MALDI-TOF (m/z): [M]+ calcd for C89H90N6, 1242.7227; found, 1242.7267.
6.3.14
Compound 1
To a 3-neck round-bottom flask was charged compound 7 (0.35 g, 1.18 mmol),
PdCl2(PPh3)2 (0.098 g, 0.14 mmol), CuI (0.045 g, 0.235 mmol), compound 17 (3.35 g,
2.58 mmol), i-Pr2NH (7.5 mL) and THF (30mL). The above solution was stirred at 90°C
under N2 for 24 hours. The cooled reaction solution was then extracted with
dichloromethane (30 mL × 3) and the organic layer was collected and dried over
MgSO4(s). After filtration and removal of the solvent, the crude product was purified
through column chromatography on silica gel using dichloromethane-hexane (1:3) as the
eluent to give the final product as pale-yellow oil with yield of 31% (1.0 g). 1H NMR (300
MHz, CDCl3) δ: 8.48 (s, 2H, H14), 8.38 (s, 2H, H5), 8.14 (s, 2H, H17), 7.96-7.93 (m, 4H,
H24), 7.90-7.87 (m, 4H, H25), 7.75-7.72 (m, 2H, H11), 7.68-7.64 (m, 2H, H8), 7.57-7.53 (m,
4H, H28), 7.48 (s, 4H, H22), 7.44-7.41 (m, 2H, H3), 7.27-7.22 (m, 20H, H2, H10, H34),
7.14-7.11 (m, 16H, H35), 7.03-6.92 (m, 16H, H29, H31, H33), 4.33-4.32 (m, 2H, Hf), 3.90 (br,
m, 8H, Hf2), 2.17-2.16 (m, 8H, Hf1), 1.92-1.90 (m, 2H, He), 1.33 (m, 14H, Hb, Hc, Hd, He2),
1.11-1.07 (m, 32H, Hc1, Hd1, He1, Hd2), 0.94 (br, m, 19H, Ha, Hb2, Hc2), 0.78-0.73 (m, 32H,
13
Ha1, Ha2, Hb1); C NMR (75 MHz, CDCl3)
δ: 153.95 (C19), 153.58 (C23), 153.46 (C23’),
151.48 (C20), 148.14 (C36), 146.50 (C16), 143.37 (C7), 142.26 (C15), 141.34 (C21), 141.28
(C21’), 140.72 (C18), 140.49 (C1), 140.30 (C13), 139.43 (C12), 136.09 (C30), 135.99 (C26),
130.93 (C8), 129.09 (C34), 126.09 (C11), 124.20 (C5), 123.93 (C35), 123.24 (C32), 122.47
(C33), 122.36 (C3), 121.12 (C10, C17), 120.96 (C14), 119.60 (C25), 118.52 (C28), 118.18
(C24), 117.00 (C27), 113.84 (C29), 112.54 (C9), 110.59 (C22), 109.08 (C2), 104.62 (C31),
99.11 (C6), 91.70 (C4), 88.83 (sp-carbon), 82.59 (sp-carbon), 55.23 (Cg1), 43.34 (Cf), 42.67
(Cf2), 41.38 (Cf1), 31.55 (Ce1), 31.45 (Ce), 31.03 (Ce2), 29.74 (Cd1), 29.65 (Cd1’), 28.87
(Cd), 28.35 (Cd2), 26.86 (Cc), 26.45 (Cc2), 23.99 (Cc1), 22.56 (Cb1), 22.48 (Cb), 22.32 (Cb2),
13.94 (Ca, Ca1, Ca2); MALDI-TOF (m/z): [M]+ calcd for C196H197N13, 2734.8210; found,
2734.8289.
6.3.15
Compound 2
To a solution of compound 8 (0.25 g, 0.44 mmol) in THF (27 mL) was added
PdCl2(PPh3)2 (0.075 g, 0.11 mmol), CuI (0.033 g, 0.17 mmol), compound 19 (2.44 g, 1.96
mmol) and i-Pr2NH (6.67mL) and the resulting mixture was stirred at 90°C under N2 for
24 hours. After cooling to the r.t., the above solution was then extracted with
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dichloromethane (30 mL × 3) and the organic layer was collected and dried over
MgSO4(s). After filtration and removal of the solvent, the crude product was purified
through column chromatography on silica gel using dichloromethane-hexane (1:3) as the
eluent to give the final product as pale-yellow oil with yield of 43% (1.0 g). 1H NMR (300
MHz, CDCl3) δ: 8.50 (s, 4H, H14), 8.16 (s, 4H, H17), 7.96-7.93 (m, 8H, H24), 7.94 (s, 2H,
H5), 7.91-7.86 (m, 8H, H25), 7.64 (br, m, 4H, H11), 7.61 (br, m, 4H, H8), 7.56-7.54 (m, 8H,
H28), 7.52 (s, 2H, H3), 7.49 (br, m, 4H, H10), 7.27-7.22 (m, 40H, H22, H34), 7.14-7.11 (m,
32H, H35), 7.03-6.93 (m, 32H, H29, H31, H33), 3.90 (br, m, 18H, Hf, Hf2), 2.19-2.11 (m,
18H, He, Hf1), 1.33 (br, m, 22H, Hb, Hc, Hd, He2), 1.11-1.07 (m, 64H, Hc1, Hd1, He1, Hd2),
13
0.95-0.94 (m, 35H, Ha, Hb2, Hc2), 0.78-0.73 (m, 64H, Ha1, Ha2, Hb1); C NMR (75 MHz,
CDCl3) δ: 154.07 (C19), 153.73 (C23), 153.47 (C1), 151.51 (C20), 148.11 (C36), 146.56
(C16), 142.83 (C7), 142.28 (C15), 141.45 (C21), 141.13 (C13), 140.78 (C6), 140.29 (C12),
135.90 (C30), 135.80 (C26), 133.56 (C3), 133.34 (C3’), 132.90 (C18), 131.95 (C8), 129.49
(C4), 129.45 (C4’), 129.08 (C34), 128.36 (C5), 128.24 (C5’), 127.55 (C11), 127.22 (C2),
123.94 (C35), 123.32 (C9), 122.48 (C33), 121.81 (C32), 121.14 (C10, C17), 120.90 (C14),
119.62 (C25, C28), 119.00 (C24), 118.12 (C27), 117.01 (C29), 110.52 (C22), 104.58 (C31),
83.19 (sp-carbon), 75.02 (sp-carbon), 55.26 (Cg1), 42.68 (Cf, Cf2), 41.20 (Cf1), 31.48 (Ce1),
31.02 (Ce, Ce2), 29.65 (Cd1), 28.35 (Cd, Cd2), 26.44 (Cc, Cc2), 23.94 (Cc1), 22.51 (Cb1),
22.31 (Cb, Cb2), 13.92 (Ca, Ca1, Ca2); MALDI-TOF (m/z): [M+H]+ calcd for C374H374N25,
5219.2773; found, 5219.2891.
Acknowledgements
TCL and HWL acknowledge the financial support from the Ministry of Science and
Technology (MOST), Taiwan under grant number: MOST 106-2119-M-008-013-,
107-2113-M-008-010-, 105-2112-M-007-016-MY3, and 105-2628-E-007-008-MY3.
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