Indole-Fused Acridone: Synthesis, Structures, Proton Transfer, and Hole-Transport Properties

Article abstract of DOI:10.1021/acs.joc.8b02939

Three pairs of regioisomers of the planar acridone derivatives (9 vs 10, 11 vs 12, and 13 vs 14), classified as the 1-cyclized compounds (9, 11, and 13) and the 3-cyclized (or 1,3′-cyclized) regioisomers (10, 12, and 14), have been synthesized, and their

Full text of DOI:10.1021/acs.joc.8b02939

Article
Cite This: J. Org. Chem. XXXX, XXX, XXX−XXX
pubs.acs.org/joc
Indole-Fused Acridone: Synthesis, Structures, Proton Transfer, and
Hole-Transport Properties
Ying-ying Jin and Qi Fang*
State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China
*
S Supporting Information
ABSTRACT: Three pairs of regioisomers of the planar
acridone derivatives (9 vs 10, 11 vs 12, and 13 vs 14),
classified as the 1-cyclized compounds (9, 11, and 13) and the
3
-cyclized (or 1,3′-cyclized) regioisomers (10, 12, and 14),
have been synthesized, and their X-ray structures have been
determined. The 1-cyclized compounds have higher yields
and lower energies compared with their 3-cyclized isomers.
The fluorescence spectra of the intramolecular H-bond
containing compounds (9, 11, 13, and 14) consist of two
bands (shorter wavelength band for the keto form and longer wavelength band for the enol form) and exhibit the feature of the
excited-state intramolecular proton transfer (ESIPT). The density functional theory (DFT) theoretical investigation of the
reorganization energy (λ) with respect to molecular symmetry revealed that planar rigid-C -symmetric polycyclic
2
v
heteroaromatic molecules (such as acridone, 1, and 13) can have low charge-transport barrier (small λ value) and keep the
invariance of the molecular point group in the charge-transport process, and therefore can have high hole mobility.
INTRODUCTION
Organic semiconductive compounds usually feature rigid
geometry and highly π-conjugated structure, such as acenes
and thienoacenes (see Table 1). We noticed that some
semiconductive compounds take the C molecular point group
■
(
Since the appearance of the organic field-effect transistors
OFETs) 30 years ago, high-performance organic semi-
conductor materials have acquired rapid progress as
summarized in several reviews.
1
2v
2
−5
and have small λ values, such as dibenzo[d,d′]thieno[3,2-b;4,5-
Designs and syntheses of
21,22
b′]dithiophene
(DBTDT, see Table 1) and dinaphtho[2,3-
new functional molecules are always the essential engines to
promote the development of organic electronic materials. On
the basis of novel compounds, numerous semiconductors with
high charge-transport mobility (μ) have been reported in
23
b:2′,3′-d]thiophene (DNT, see Table 1).
To investigate the influence of symmetry on reorganization
energy (λ), we carried out more λ-calculations for polycyclic
aromatic and heteroaromatic molecules with different point
groups and different π-dimensions. The λ values of the well-
known D -symmetric acenes are listed in the entry 1 of Table
6
−17
recent years.
The structure−property correlations of
organic semiconductors can be focused on the following
equation
2h
1
. If one central carbon atom of the above acenes was replaced
by a nitrogen atom, the resultant C -symmetric compounds in
the entry 2 of Table 1 would have smaller λ values. The
1
/2
2v
i
y
i
j
y
e
j π z
λ z
2
2
j
z
j
z
μ = 2
k Tℏ λk T
j
z
d t expj−
4k T
z
j
j
z
z
j
j
z
z
comparison of the pairwise isomers of thienoacene com-
B
k
B
{
k
B
{
(1)
5
,24−26
pounds
in the entries 4 and 5 indicates that the C2v
18,19
which is based on the Marcus electron-transfer theory
and
compounds here are superior to their C2h isomers. Some
multilayer polycyclic aromatic and heteroaromatic compounds
are collected in the entries 6 and 7, where the λ values of the
the well-known hopping model. In the mobility expression 1, λ
is the reorganization energy and is the property of the
molecule, and t is the transfer integral which is jointly
dependent on the molecule and the intermolecular interactions
in the crystal. Therefore, minimization of the λ is of the
upmost importance in designing organic semiconductors at the
molecular level and the λ can be quantum chemically predicted
C
2v-symmetric compounds 7-1 and 7-2 are about half of those
of the similar π-dimensional D - and C -symmetric
2h
2h
compounds in the entry 6 and the λ value of the biradical 7-
3
is only a quarter of that of the similar π-dimensional ovalene.
Generally, extension of the π-conjugation tends to reduce
2
0
the λ in acene system, such as the larger λ of anthracene and
the smaller λ of tetracene (see Table 1). The same tendency
(
vide infra). When not specified, the calculations for λ,
energies, and geometric optimizations in this work were carried
out by the DFT/B3LYP/6-311g(d) methods. The λ is for the
27
was also reported for thienoacene system. However, as
hole-transport process (λ = λ ); if otherwise, for electron-
h
transport process the reorganization energy will be denoted by
Received: November 19, 2018
λ .
e
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Table 1. Calculated Reorganization Energies (λ in meV) of Some Compounds with Various Molecular Point Groups by DFT/
B3LYP/6-311g(d) Methods
a
b
c
Unknown compounds which cannot be found in the Web site of SciFinder. The point groups in parentheses are of the cation. The calculated
triplet state of compound 7-3 is 0.81 eV lower than that of the singlet state.
shown in the entry 3 of Table 1, the λ value (97.7 meV) of the
small-size C -type acridone is much smaller than that (143.4
semiconductive material. Herein, the syntheses, X-ray
structures, photophysical properties, and theoretical hole-
transporting behaviors of the series of indole-fused acridone
compounds 9−14 (see Scheme 1) are reported.
2v
meV) of the large-size C -type quinacridone, implying the
2
h
advantage of the C symmetry. For the synthetic facility, the N
2v
atom of acridone was methylated to improve solubility, and the
point group of the resultant compound 1 (see Table 1)
degenerates to C or quasi-C . This methylation does not
affect the molecular rigidity but further reduces the λ value (1
vs acridone).
RESULTS AND DISCUSSION
1. Syntheses of Compounds 9−14. We initially
attempted to synthesize the precursor 8 of 13 by route 1
■
s
2v
(
see Scheme 1). However, after Suzuki coupling of 1 equiv of 3
From syntheses and materials perspectives, acridone has
good air and thermal stability and it can be easily modified. Up
to now, reports about the syntheses and the charge-transport
properties of π-fused acridone derivatives are very limited.
With the above ideas in mind, we synthesized π-extended Cs-
and 4 equiv of 2-nitrophenylboronic acid, we isolated 7 instead
of the expected 8, together with the debromination
compounds 1 and 2. Presumably this failure should be caused
by the strong electron-withdrawing effect of the nitro
28−31
32
substituent. Compound 7 was then treated with excess
33
or quasi-C -symmetric compound 13 (see Scheme 1) by
amount of PPh in 1,2-dichlorobenzene (o-DCB) at 180 °C
2v
3
fusing two indole units to the parent compound 1. The term
quasi-C symmetry for compounds 1 and 13 is based on the
for 36 h, obtaining 1-cyclized compound 11 and 3-cyclized
compound 12, which have been well-separated via silica gel
chromatography.
2
v
fact that their non-hydrogen molecular skeletons have C2v
symmetry. The λ value of compound 13 (105.3 meV) is
between those of C -type of DBTDT and DNT, implying that
To obtain compound 13, we then designed route 2 shown in
Scheme 1. First the dibrominated 3 was reacted with
bis(pinacolato)diboron (B pin ) to give 5 in 79% yield. After
2
v
acridone derivatives may be a kind of potential organic
2
2
B
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Scheme 1. Synthetic Procedure for 9−14
Suzuki coupling of 5 and 2-nitroiodobenzene, the precursor 8
was obtained in 70% yield. Then, treating 8 with excess
amount of PPh in o-DCB at 180 °C for 36 h, we finally
3
obtained a pair of regioisomers, which were demonstrated to
be the 1,1′-cyclized compound 13 (yield 67%) and the 1,3′-
cyclized compound 14 (yield 9.7%) by NMR and single-crystal
X-ray diffractions. Both 13 and 14 are highly π-conjugated
heteroarenes with seven fused rings. However, the supposed
3
,3′-cyclized regioisomer, 15, was not found. On the basis of
the optimized molecular geometries, the total energy of 15 was
calculated to be 0.49 and 0.24 eV higher than those of 13 and
Figure 1. Low-field region of 1H NMR spectra of two pairs of
regioisomers (9 vs 10, 13 vs 14) in DMSO-d6.
1
4, respectively, which can rationalize the higher yield of 13
and the failure for forming 15.
We also designed route 3 (see Scheme 1) and synthesized
the 1-cyclized compound 9 and the 3-cyclized regioisomer 10,
with the yield being 84% and 10%, respectively.
By comparing the three pairs of regioisomers (9 vs 10, 11 vs
N−H with and without intramolecular hydrogen bonding,
respectively.
12, and 13 vs 14), we noticed that the 1-cyclized (9 and 11)
2. Structural Characterization. Crystals of compounds
and 1,1′-cyclized (13) compounds have higher yields, lower
energies, and smaller dipole moments than those of the 3-
cyclized (10 and 12) and the 1,3′-cyclized (14) ones,
respectively. We believe that the higher yield of the 1-
cyclization can be partly attributed to their lower energies and
the formation of intramolecular N−H···O hydrogen bonds.
9
−14 were grown by slow evaporation of their CH Cl
2
2
solutions, and their X-ray structure data are listed in Table 2
and Tables S1−S3. All the molecules of 9−14 in their crystals
and in the optimized isolated states are planar (Figures 2−4).
The 1-cyclized (9 and 11), 1,1′-cyclized (13), and 1,3′-
cyclized (14) compounds have intramolecular N−H···O
hydrogen bonds (listed in Tables S1−S3), which help to
form a kind of six-membered ring (see Figures 2 and 3).
As shown in Figure 3, two crescent-shaped molecules of 13
embrace each other by two intermolecular N2−H2···O1
hydrogen bonds to pose an X-shaped dimer with a dihedral
angle of 50.5°. Molecules are parallelly packed along the b-axis
direction with the two parallel adjacent molecular dipole
moments being in the opposite orientation, giving rise to a
type of one-dimensional (1-D) molecular column with
alternate π···π distances of 3.401 and 3.431 Å. Along the c-
axis direction, neighboring molecular columns are connected
by the intermolecular N2−H2···O1 hydrogen bonds of the X-
shaped dimers. On the basis of the electronic energies of the
optimized momomer (E ) and the optimized dimer (E ), the
1
All the new compounds 9−14 were fully characterized by H
1
3
NMR, C NMR, high-resolution mass spectrometry (HRMS),
and X-ray single-crystal diffractions (see Figures 2−4). The
spectra/spectrometries and crystallographic data are in the
Supporting Information. Generally, the intramolecular N−H···
1
O hydrogen bond leads to a downfield shift of the H−N
2
9
NMR signal, and this effect can be conveniently used to
identify the regioisomers (9 vs 10, 13 vs 14). As shown in
Figure 1, the N−H peak of compound 10 is at 11.57 ppm,
while that of its regioisomer 9 is downfield shifted to 12.25
ppm. The 1,1′-cyclized 13 has two same hydrogen bonding
N−H protons, and the unique N−H peak was observed at the
lower field side of 12.11 ppm. However, the two N−H protons
of the asymmetric 1,3′-cyclized 14 are different with the 12.23
and 11.58 ppm peaks corresponding to the N−H···O and the
1
2
energy of the intermolecular N2−H2···O1 hydrogen bond was
C
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Table 2. Structure Data and Optoelectronic Properties of 1 and 9−14
1
9
10
11
12
13
14
T (K)
space group
a (Å)
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
dipole moment (D)
λabs (nm)
λem (nm)
τ (ns)
Φ (%)
E1 (eV)
296(2)
P-1
294(2)
295(2)
C2/c
293(2)
P-1
295(2)
C2/c
294(2)
P2 2 2
1 1 1
P2 /n
1
15.5365(7)
15.5527(7)
25.558(1)
76.770(1)
76.127(1)
89.681(1)
5828.4(4)
4.223
7.732(2)
21.217(6)
8.849(2)
90
92.940(4)
90
1449.8(6)
6.567
419(372.3)
437
28.3133(6)
7.5509(2)
15.6708(3)
90
109.509(1)
90
7.3885(10)
11.919(2)
17.597(2)
96.437(2)
90.969(2)
98.162(2)
1523.5(4)
8.088
29.7977(5)
7.5553(1)
16.4954(3)
90
100.342(1)
90
5.6465(8)
10.134(2)
31.872(5)
90
90
90
3157.9(1)
5.000
3653.3(1)
3.067
1823.7(5)
5.914
a
b
400(349.1)
412
7.0
28.8
1.34
−5.67
−670.0415
416(383.7)
425(395.7)
427(382.2)
448
5.6
424(392.4)
433(395.3)
c
d
c
d
c
d
c
d
450 , 658
459 , 678
445 , 634
454 , 646
2.0, 3.2
0.47
1.14
8.2
31.5
1.3, 1.7
1.24
1.09
−5.42
−1240.4675
1.5, 1.9
1.9
e
0.29
1.17
−5.50
−3528.8082
15.3
f
f
EHOMO (eV)
energy (hartree)
−5.47
g
−955.2548
−955.2456
−3528.7992
−1240.4588
a
b
Calculated values based on optimized geometries. λ is the UV absorption maximum in CH Cl at the longest wavelength band, and the data in
abs
2
2
c
d
the parentheses are the calculated maximum of the S −S transition by TD-DFT/6-311g(d) methods. The K-band emission maximum. The E-
0
1
e
f
band emission maximum in CH Cl , with λ = λ . Determined in CH Cl , using coumarin 307 in MeOH as reference (Φ = 0.53). The first
2
2
ex
abs
2
2
g
redox potential was measured by cyclic voltammetry with Ag/AgCl reference electrode, see Figure 9. Sum of electronic and zero-point energies,
results from DFT calculation at the level of B3LYP/6-311g(d).
Figure 2. Ortep drawing of the X-ray molecular structures of compounds 9, 10, 11, and 12.
Figure 3. Crystal structure of compound 13. (a) The X-shaped dimer connected by the N−H···O hydrogen bonds. (b) The packing diagram,
showing the π···π distances and the dihedral angle of an X-shaped dimer.
calculated to be (2E1 − E )/2 = 13.0 kJ/mol (see the
differently oriented and separately form four 1-D molecular
columns along the a-axis direction. All these 1-D molecular
columns have a uniform and very short π···π distance of 3.335
Å, which is favorable for charge transport (vide infra).
3. Photophysical and Electrochemical Properties. As
shown in Figure 5a and Table 2, the long-wavelength
2
Supporting Information for details).
As shown in Figure 4a, the molecule of 14 in the crystal is
disordered over two positions. The major position (site
occupation factor 53.5%) and the minor position are
approximately mirror images of each other. The crystallo-
graphic disorder may obscure the molecular structure;
fortunately, the correctness of the structure 14 can be
absorption maximum (λ ) of compounds 13 (424 nm) and
abs
14 (433 nm) are red-shifted compared to that of 9 (416 nm)
and 10 (419 nm), which are in turn red-shifted relative to that
of 1 (400 nm), as a result of the π-extension from the three-
1
supported by the H NMR spectra (see Figure 1 and Figure
S33). As shown in Figure 4b, four molecules in the unit cell are
D
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Figure 4. Crystal structure of compound 14. (a) The disordered molecule, consisting of the major part (in black and solid line) and the minor part
in gray or dash line). (b) The packing diagram shows the uniform 1-D columnar structure. For clarity, the minor part has been omitted.
(
Figure 5. Absorption spectra (a) and fluorescence spectra (b) for two pairs of regioisomers (9 vs 10, 13 vs 14) and compound 1 in CH Cl (c = 20
2
2
μM, λex = λabs).
fused-ring to the five-fused-ring and to the seven-fused-ring
systems. The TD-DFT-calculated λabs values (in Table 2) of all
these compounds correspond to the HOMO → LUMO
transition (Tables S4−S9 and S11).
As shown in Figure 5b, the emission maximum of compound
is at 412 nm and the similar emission of 3-cyclized
1
compound 10 is red-shifted to 437 nm. By comparison, the
fluorescence spectra of the intramolecular H-bond containing
compounds (9, 13, and 14) consist of two bands. The normal
emission band (450 nm for 9, 445 nm for 13, and 454 nm for
1
4) can be attributed to the K* → K emission of the keto form
Figure 6. Schematically shown photophysical−photochemical cycle of
compound 13: (1) K → K* intramolecular charge transfer; (2) K*→
E* excited-state intramolecular proton transfer (ESIPT); (3) E* → E
intramolecular charge transfer; (4) E→ K ground-state intramolecular
reverse proton transfer.
(
K), which is associated with the intramolecular charge-
transfer (CT) process (see Figure 6 and Tables S5 and S9−
S11). The red-shifted emission band (658 nm for 9, 634 nm
for 13, and 646 nm for 14) can be assigned to the E* → E
emission of enol form (E). This kind of dual emission can be
related to the excited-state intramolecular proton transfer
The ratios of I /I in polar and protic CH OH, however, are
E
K
3
34−36
(
ESIPT) process.
Taking compound 13 for example (see
dramatically decreased to 0.76 (13) and 0.56 (14). This can be
Figure 6), upon excitation of the keto form (K) to its charge-
transfer state (K*), the K* will emit the K* → K CT band;
then, following the K* → E* ESIPT reaction, the E* will emit
the red-shifted E* → E band. The K-form of 13 is more stable
than the E-form, for the calculated energy of the K-form of 13
is 0.80 eV lower than that of the E-form.
attributed to the intermolecular H-bond characterized
solvation in CH OH, which is more favorable for the keto
3
form.
The fluorescence spectra of compounds 13 and 14 exhibit a
sharp turn-on response to trifluoroacetic acid (TFA). As
shown in Figure 8, there appears a new enhancing emission
band for both 13 and 14 upon titration with TFA, with a
concomitant attenuation of the K-band emission. This new
intense band (590 nm for 13 and 583 nm for 14) is blue-
shifted compared to the E-band. Presumably this new band is
originated from a kind of trifluoroacetic salt of 13 or 14.
As shown in Figure 7 and Figure S36, the emission intensity
ratio (I /I ) of compounds 9, 13, and 14 is sensitive to solvent
E
K
polarity. In nonpolar and aprotic benzene, the fluorescence
spectra exhibit prominent E-emission (I ) and minor K-
E
emission (I ) with the I /I ratios of 4.6 (13) and 6.1 (14).
K
E
K
E
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Figure 7. Fluorescence spectra of 13 (a) and 14 (b) in different solvents (c = 20 μM, λ = 425 and 431 nm for 13 and 14 in benzene; λ = 423 and
ex
ex
4
33 nm for 13 and 14 in CH Cl ; λ = 419 and 438 nm for 13 and 14 in CH OH).
2
2
ex
3
Figure 8. Fluorescence spectra changes of 13 (left, c = 36 μM, λex = 423 nm) and 14 (right, c = 21 μM, λex = 433 nm) in CH Cl upon titration
2
2
with TFA.
Crystals of 14/TFA grown in TFA were obtained, which have
different cell parameters to those (in Table 2) of the crystal 14
grown in CH Cl . Unfortunately, the 14/TFA crystal is not
HOMO of 1 is −[4.8 + (1.34 − 0.47)] = −5.67 eV. In the
same way, the HOMO of 9 and 13 were measured to be −5.47
and −5.42 eV, respectively. These results indicate that with the
increase of π-conjugation (from 1 to 9 and to 13) the electron-
donating abilities show the sequence of 1 < 9 < 13.
2
2
good enough for a full X-ray structural determination.
As shown in Figure 9, the first redox pair of the cyclic
voltammograms of 9 and 13 is quasi-reversible, while that of
the 10 and 14 are irreversible (Figure S41). Ferrocene (Fc)
was used as a standard, and its highest occupied molecular
4
. Theoretical Survey of the Charge-Transport
Properties. The charge-transport properties of organic
crystals depend on many extrinsic parameters (such as
temperature and pressure) and materials factors (such as the
37
orbital (HOMO) energy was taken to be −4.8 eV. The first
38
purity and the perfectness of the crystals). At the microscopic
level, the crucial structural variables in the framework of the
hopping model (the mobility expression 1) are the
reorganization energy λ and the transfer integral t. A hopping
hole-transport process
redox potentials E of 1 and that of the ferrocene were
1
measured to be 1.34 and 0.47 eV, respectively; thus, the
+
+
(
2)
M···M → M ···M
not only means the transfer of an electron from neutral
+
molecule M to cation M , but also means the exchange of the
+
geometries between M and M .
λ
0
0
+
0
+
+
+
0
0
M + M → [M + M ] → M + M
(3)
+
0
+
where the superscript (0 or + ) represents the charge of the
molecule or its cation (the hole) and the subscript (0 or + )
denotes the geometry of the stable molecule or cation.
As illustrated in Figure 10, the λ for the hole transport can
Figure 9. Cyclic voltammograms of 1, 9, and 13 in CH Cl (1 mM),
39
2
2
be expressed by
scanned at a rate of 50 mV/s with n-Bu NPF (0.1 M) as supporting
4
6
electrolyte. The Pt wires were used as working and counter electrodes,
and Ag/AgCl was used as the reference electrode.
0
0
+
+
λ = λ + λ = (E − E ) + (E − E )
(4)
1
2
+
0
0
+
F
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
which is about half the value (λ = 147.5 meV) of the same π-
dimensional pyrene (16 π-electrons). To check our calculating
methods, the λ value of the well-known organic semiconductor
pentacene was also calculated to be 97.9 meV, which is well-
41
consistent with the reported 99.3 meV.
The reorganization energy λ characterizes the charge-
transfer barrier, and small λ implies the rigid molecular
geometry. The rigidity of the geometry not only means the
molecule, but also means the small structural difference
between the molecule and its cation. We suppose that one
of the necessary conditions for small λ is the same point group
of the molecule and its cation. The optimized isolated DT-
TTF molecule (see Table 1) has a boat-shaped C symmetry
Figure 10. Schematic illustration of a circle of hole transport and the
reorganization energy λ; the potential curves here are of the hydrogen
2v
46
(
though the crystallized DT-TTF molecule is quasi-D );
2h
+
molecule H and its cation H calculated by DFT/B3LYP/6-311+
+
2
2
however, the isolated DT-TTF cation belongs to planar D
2h
+
g(3df,3pd) methods. The shapes of the potential curves can also
point group. Thus, the DT-TTF molecule is not very rigid and
has a moderate λ value (see Table 3). The large λ value (0.70
eV) of triindole (see entry 3 of Table 1) can be attributed to
the inconsistency of the point group in the hole-transport
process: the higher symmetric (C ) triindole molecule
interpret the fact that for most cases λ and λ are proximately equal.
1
2
0
where λ measures the difference between the energy (E ) of
1
0
0
the stable (optimized) molecule and the energy (E ) of the
+
3
h
molecule with the stable cation geometry and λ measures the
2
degenerates to the lower symmetric (C ) cation. The similar
s
+
difference between the energy (E ) of the stable (optimized)
cation and the energy (E ) of the cation with the stable
molecule geometry. All the four terms (E , E , E , and E )
+
symmetry degeneration can also be found (see entry 3 of Table
+
0
1) for the beautiful coronene (D6h → D ) and sulflower (D
2h
8h
0
0
0
+
0
+
+
+
→ C ). On the other hand, the planar acridone and other
2h
are individually the sum of electronic and zero-point energies.
There are no minus frequencies in the calculated results of
quinacridone, acridone, 1, 13, and 14. The λ calculation in this
work was based on an isolated molecule and its cation without
planar C molecules in Table 1 are invariably C -symmetric,
2
v
2v
from the neutral state to the cation state. These kinds of
geometric stable planar molecules may be referred to as rigid-
C2v-type molecules.
For the sake of simplicity, only the 1-D hole mobility (μ)
along the face-to-face π-columnar direction (see Figure 11) at
20
considering the crystalline effect and intermolecular inter-
4
0
actions. An exception is for dithiophenetetrathiafulvalene
(
DT-TTF, see Tables 1 and 3); its λ value was calculated by
3
00 K has been calculated by eq 1, and the results are listed in
20
using the cage model.
Table 3. The calculated μ values of the rigid-C -type
2
v
The t in eq 1 is a scale of the intermolecular interactions
compounds acridone, 1, and 13 are significantly larger than
that of the semiconductive compound quinacridone. The
unexpectedly large μ value of 14 can be attributed to its
exceptionally large t value resulting from the very small π···π
distance (3.335 Å). These results indicate that the acridone
system may be a promising p-type organic semiconductor
material. The μ value of the semiconductive compound DT-
TTF along the face-to-edge direction has also been calculated
between two neighboring molecules and can be approached
4
1
by
t = 12 (EHOMO − EHOMO − 1
)
(5)
where EHOMO and EHOMO − 1 are the energies of the HOMO
and HOMO − 1 of the two-molecule pair, respectively. The t
calculation is based on the geometry of the concerned two-
molecule pair in the crystal without optimization (see Figure
(
see Table 3), which can be compared to the experimental
4
results (see Table 3), giving a support to the reliability of the
calculating methods.
1
1).
The λ and t values listed in Table 3 were calculated by DFT/
B3LYP/6-311g(d) methods by using the Gaussian 09
4
2
CONCLUSION
program. The d in eq 1 is the distance between the two
centroids of the two neighboring molecules in the crystal along
the charge-transfer direction.
■
In summary, the syntheses, structures, and optoelectronic
properties of two series (1-cyclized and 3-cyclized) of new
indole-fused acridone derivatives have been reported. The
fluorescence spectra of the 1-cyclized compounds exhibit
interesting ESIPT. It is well-known that the π-conjugation and
As shown in Table 3, the C - or quasi-C -symmetric
2v
2v
acridone compounds are characterized by small λ. Compound
has 16 π-electrons and a very small λ value (71.5 meV),
1
Table 3. Structural Parameters and the Calculated Hole Mobilities (T = 300 K) of Representative Crystals
μ/cm V s−1
2
−1
compds
point group
λ/meV
t/meV
d/Å
a
b
quinacridone
C2h
C2v
quasi-C2v
quasi-C2v
C1
143.4
97.7
71.5
105.3
108.0
256.6
50.3
91.0
44.1
51.7
183.7
100.1
3.98
4.53
5.11
5.35
5.65
5.81
0.85 (0.2)
a
acridone
6.84
3.09
2.77
37.4
a
1
c
c
1
1
3
4
a
b
DT-TTF
C2v (D2h for cation)
1.81 (3.6)
a
b
The X-ray data for the μ calculation are cited from refs 43 for quinacridone, 44 for acridone, 45 for 1, and 46 for DT-TTF. The μ values in
c
parentheses are the experimental results cited from refs 31 for quinacridone and 4 for DT-TTF. The average values.
G
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Figure 11. Charge transport in the 1-D π-columnar structures of compounds (a) acridone, (b) 13, and (c) 14. The X-ray data of acridone is from
the ref 44.
charge-transfer nature are the two basic structural factors that
influence the functions of organic electronic materials.
However, the effect of the molecular symmetry on the
charge-transport properties of organic semiconductors was
rarely concerned. On the basis of the experimental and
theoretical studies in this work, we suppose that one of the
necessary conditions for low reorganization energy (λ) of
crystalline p-type organic semiconductors is the same point
group of the molecule and its cation. This work also
procedure above for synthesizing 2, 1.398 g of yellow solid 3 was
1
obtained in 80% yield. H NMR (300 MHz, CDCl ): δ 8.65 (d, J =
3
2
.4 Hz, 2H), 7.81 (dd, J = 9.2, 2.6 Hz, 2H), 7.44 (d, J = 9.3 Hz, 2H),
1
3.89 (s, 3H). The H NMR data of compound 3 are consistent with
1
the reported H NMR data of the same compound in ref 49.
2
-Bpin-10-methyl-acridone (4). A solution of 2 (0.401 g, 1.40
mmol), bis(pinacolato)diboron (B pin ) (0.519 g, 2.04 mmol),
2
2
Pd(dppf)Cl (PPh ) (0.030 g, 0.041 mmol), and KOAc (0.412 g,
2
3 2
4.21 mmol) in degassed 1,2-dimethoxyethane (DME) (20 mL) was
stirred at 80 °C under N for 24 h. After cooling to room temperature,
2
demonstrated that the planar rigid-C -symmetric acridone
2v
the solvent was removed by rotary evaporation, and the residue was
dissolved in CH Cl . Then, the organic layer was washed with water,
compounds can have very low charge-transport barrier (small
λ) and high mobilities, and therefore they may be a kind of
promising hole-transport material.
2
2
dried over anhydrous MgSO , filtered, and concentrated under
4
reduced pressure. The product was purified by silica gel column
chromatography (petroleum ether/ethyl acetate = 8:1) to give 0.451 g
1
of pale yellow solid in 96% yield. H NMR (300 MHz, CDCl ): δ
3
EXPERIMENTAL SECTION
Syntheses and Chemical Characterization. NMR spectra were
recorded on a Bruker AVANCE (300 and 400 MHz) in CDCl or
■
9.04 (d, J = 1.5 Hz, 1H), 8.57 (dd, J = 8.0, 1.7 Hz, 1H), 8.09 (dd, J =
8.7, 1.5 Hz, 1H), 7.72 (t(d,t,d), J = 7.8, 1.8 Hz, 1H), 7.52 (d, J = 8.7
Hz, 1H), 7.48 (d, J = 8.7 Hz, 1H), 7.30 (t, J = 7.4 Hz, 1H), 3.89 (s,
3
1
3
DMSO-d with tetramethylsilane (TMS) as an internal reference. The
6
3H), 1.37 (s, 12H). C NMR (100 MHz, CDCl ): δ 178.0, 144.5,
3
HRMS of compounds 4−8 was performed on an electrospray
ionization time-of-flight (ESI-TOF) mass spectrometer, and the
HRMS of compounds 9−14 was performed on a Thermo Fisher
Scientific LTQ FTICR-MS instrument with direct analysis in real time
1
8
3
42.6, 139.5, 135.7, 133.9, 128.0, 122.9, 121.8, 121.6, 114.9, 113.9,
+
4.0, 33.8, 25.0. HRMS (ESI) m/z[M + H] : calcd for C H BNO ,
2
0
23
3
36.1771; found, 336.1768.
,7-Bis(Bpin)-10-methyl-acridone (5). A solution of 3 (0.513 g,
.40 mmol), B pin (1.071 g, 4.22 mmol), Pd(dppf)Cl (PPh )
2
(
DART) positive ion mode. All the reactions were carried out under
2
1
2
2
2
3 2
N atmosphere using standard Schlenk techniques and heated with an
(0.030 g, 0.041 mmol), and KOAc (0.827 g, 8.44 mmol) in degassed
DME (20 mL) was stirred at 80 °C under N for 24 h, and then
following the same procedure above for synthesizing 4, 0.512 g of pale
yellow solid was obtained in 79% yield. H NMR (400 MHz, CDCl ):
oil bath. Melting points (mp) were measured on a Tektronix XT-4
instrument. UV−vis absorption spectra were recorded on a Shimadzu
UV−vis spectrophotometer (UV-2550). Steady-state fluorescence
spectra and decay curves were recorded on an Edinburgh FLS920
2
1
3
δ 9.05 (s, 2H), 8.11 (d, J = 8.4 Hz, 2H), 7.50 (d, J = 8.8 Hz, 2H), 3.92
fluorescence spectrometer equipped with a Xe lamp and a H lamp
13
2
(s, 3H), 1.38 (s, 24H). C NMR (100 MHz, CDCl ): δ 178.1, 144.5,
3
and a time-correlated single-photon-counting (TCSPC) card. The
redox potentials were measured by cyclic voltammetry on a
PARSTAT 2273 potentiostat. Compound 1 was synthesized
139.5, 135.8, 122.4, 114.0, 84.0, 33.9, 25.0. HRMS (ESI) m/z[M +
+
H] : calcd for C H B NO , 462.2623; found, 462.2617.
2
6
34
2
5
47
2-(2-Nitrophenyl)-10-methyl-acridone (6). To a solution of 4
according to literature methods.
-Bromo-10-methyl-acridone (2). To a solution of 1 (0.451 g,
.16 mmol) in 20 mL of DMF was added dropwise a solution of NBS
(0.450 g, 1.34 mmol), 2-nitroiodobenzene (0.401 g, 1.61 mmol), and
2
K CO (0.556 g, 4.03 mmol) in 24 mL of degassed solvents of DME/
H O (5:1) was added Pd(PPh ) (0.050 g, 0.043 mmol). Then, the
mixture was heated to 100 °C under N for 24 h. After the reaction
mixture was cooled to rt, the DME was removed by rotary
evaporation. The residue was dissolved in CH Cl , and then the
organic layer was washed with water, dried over anhydrous MgSO4,
filtered, and concentrated under reduced pressure. The product was
purified by silica gel column chromatography (petroleum ether/
CH Cl = 1:3) to give 0.333 g of orange powder in 75% yield. Mp
2
3
2
2
3 4
(
N-bromosuccinimide) (0.460 g, 2.58 mmol) in 10 mL of DMF at 0
2
°C. The reaction mixture was stirred at 85 °C for 24 h. After cooling
to room temperature, the mixture was quenched with water and
filtrated. The residue was washed with the mixed solvents of
petroleum ether/CH Cl (50 mL, 50:1) to give 0.502 g of yellow
2
2
2
2
1
solid 2 in 81% yield. H NMR (300 MHz, CDCl ): δ 8.66 (d, J = 2.4
3
Hz, 1H), 8.55 (dd, J = 8.0, 1.7 Hz, 1H), 7.80−7.73(m, 2H), 7.54 (d, J
=
8.7 Hz, 1H), 7.42 (d, J = 9.0 Hz, 1H), 7.32(t, J = 7.5 Hz, 1H), δ
2
2
1
1
3.90 (s, 3H). The H NMR data of compound 2 are consistent with
237−238 °C. H NMR (400 MHz, CDCl ): δ 8.603 (d, J = 10.4 Hz,
3
1
the reported H NMR data of the same compound in ref 48.
,7-Dibromo-10-methyl-acridone (3). To a solution of 1 (1.001 g,
.79 mmol) in 40 mL of DMF was added dropwise a solution of NBS
2.151 g, 12.08 mmol) in 20 mL of DMF at 0 °C. The reaction
mixture was stirred at 90 °C for 24 h, and then following the same
1H), 8.599 (d, J = 10.0 Hz, 1H), 7.95 (dd, J = 8.0, 1.2 Hz, 1H), 7.78
(t(d,t,d), J = 7.8, 1.6 Hz, 1H), 7.70−7.64 (m, 2H), 7.61−7.57 (m,
3H), 7.53 (t(d,s,d), J = 7.8, 1.2 Hz, 1H), 7.35 (t, J = 7.6 Hz, 1H), 3.96
2
4
(
1
3
(s, 3H). C NMR (100 MHz, CDCl ): δ 177.8, 149.0, 142.5, 142.3,
135.4, 134.1, 133.4, 132.7, 132.5, 130.6, 128.4, 127.9, 127.2, 124.5,
3
H
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
1
22.7, 122.5, 121.7, 115.3, 114.9, 33.8. HRMS (ESI) m/z[M + H]+:
calcd for C H N O , 331.1083; found, 331.1078.
2
0.440 mmol) in 5 mL of degassed o-DCB was added PPh (1.001 g,
3
3.82 mmol). Then, the mixture was heated to 180 °C under N for 36
20
15
2
3
2
-(2-Nitrophenyl)-7-bromo-10-methyl-acridone (7). To a solu-
tion of 3 (0.153 g, 0.417 mmol), 2-nitrophenylboronic acid (0.300 g,
.80 mmol), and K CO (0.350 g, 2.53 mmol) in 12 mL of degassed
h. After the reaction mixture was cooled to rt, it was directly mixed
with excess amount of silica gel powder, and then purified by silica gel
column chromatography. The first main component was eluted out by
an eluent of petroleum ether/CH Cl = 1:2, obtaining 0.141 g of 11
1
2
3
solvents of DME/H O (5:1) was added Pd(PPh ) (0.019 g, 0.016
2
3
4
2
2
mmol). Then, the mixture was heated to 100 °C under N for 48 h.
in 85% yield. The second component was eluted out by an eluent of
2
After cooling to rt, 60 mL of CH Cl was added to the reaction
petroleum ether/CH Cl = 1:5, obtaining 0.023 g of 12 in 14% yield.
2
2
2
2
1
mixture with stirring to extract the product to the liquid phase. Then,
after the insolvables were filtered out, the organic liquid phase was
washed with a large amount of water to remove DME and residual
inorganic salts in solution. The resultant crude product was purified
by silica gel column chromatography (CH Cl ) to obtain 0.055 g of
Characterization Data of 11. Mp > 300 °C. H NMR (400 MHz,
CDCl ): δ 11.46 (s, 1H), 8.76 (d, J = 2.4 Hz, 1H), 8.42 (d, J = 8.8 Hz,
3
1H), 8.11 (d, J = 7.6 Hz, 1H), 7.83 (dd, J = 9.2, 2.4 Hz, 1H), 7.65 (d,
J = 8.4 Hz, 1H), 7.54 (d, J = 9.2 Hz, 1H), 7.48 (t(d,s,d), J = 7.7, 1.0
Hz, 1H), 7.34 (d, J = 8.8 Hz, 1H), 7.34 (t, J = 7.2 Hz, 1H), 4.04 (s,
2
2
1
13
crystalline orange powder of 7 in 32% yield. H NMR (400 MHz,
3H). C NMR (100 MHz, CDCl ): δ 136.1, 129.4, 127.3, 125.2,
3
CDCl ): δ 8.70 (d, J = 2.4 Hz, 1H), 8.58 (d, J = 2.0 Hz, 1H), 7.96
120.3, 119.5, 117.1, 111.6, 105.5, 34.8, 29.7 ppm (because of the poor
3
1
3
(
dd, J = 8.0, 1.2 Hz, 1H), 7.83 (dd, J = 9.2, 2.4 Hz, 1H), 7.70−7.65
solubility the C NMR spectra is incomplete.). MS (DART) m/z[M
+
+
(
m, 1H), 7.67 (d, J = 8.8 Hz, 1H), 7.59 (d, J = 8.4 Hz, 1H), 7.57 (dd,
+ H] : 379.0. HRMS (DART) m/z[M + H] : calcd for
J = 7.6, 1.6 Hz, 1H), 7.56−7.52 (m, 1H), 7.48 (d, J = 9.2 Hz, 1H),
C H ON Br, 377.0284; found, 377.0281
2
0
14
2
.95 (s, 3H). 13C NMR (100 MHz, CDCl ): δ 149.0, 136.8, 135.2,
1
3
1
1
Characterization Data of 12. Mp > 300 °C. H NMR (300 MHz,
3
33.7, 132.7, 132.4, 131.0, 130.3, 128.5, 127.3, 124.5, 124.0, 123.2,
DMSO-d ): δ 11.60 (s, 1H), 9.10 (s, 1H), 8.43 (d, J = 2.4 Hz, 1H),
6
+
22.6, 116.9, 115.3, 115.1, 34.0. HRMS (ESI) m/z[M + H] : calcd
8.28 (d, J = 7.8 Hz, 1H), 7.91 (dd, J = 9.3, 2.4 Hz, 1H), 7.83 (d, J =
9.3 Hz, 1H), 7.61 (s, 1H), 7.52 (d, J = 8.1 Hz, 1H), 7.45 (td, J = 7.5,
1.2 Hz, 1H), 7.24 (t(d,s,d), J = 7.4, 1.1 Hz, 1H), 3.98 (s, 3H).
for C H BrN O , 409.0188; found, 409.0186.
20
14
2
3
1
3
2
,7-Bis(2-nitrophenyl)-10-methyl-acridone (8). To a solution of 5
0.813 g, 1.76 mmol), 2-nitroiodobenzene (1.351 g, 5.43 mmol), and
K CO (1.458 g, 10.57 mmol) in 36 mL of degassed DME/H O
C
(
NMR (100 MHz, DMSO-d ): δ 176.0, 145.3, 142.0, 142.0, 141.8,
6
136.2, 128.9, 127.1, 122.9, 122.7, 121.2, 120.2, 120.2, 119.6, 119.0,
2
3
2
+
(
5:1) was added Pd(PPh ) (0.100 g, 0.087 mmol). The mixture was
116.3, 113.1, 111.5, 95.2, 34.8 ppm. MS (DART) m/z[M + H] :
3
4
+
heated to 100 °C under N for 24 h. Then, the same subsequent
379.0. HRMS (DART) m/z[M + H] : calcd for C20
H
14ON
2
Br,
2
treatment of synthesizing compound 6 was carried out to obtain crude
product, which was purified by silica gel column chromatography
377.0284; found, 377.0280.
10-Methyl-indolo[2,3-a]-indolo[2,3-a′]acridone (13) and 10-
Methyl-indolo[2,3-a]-indolo[3,2-b′]acridone (14). To a solution of
8 (0.628 g, 1.391 mmol) in 10 mL of degassed o-DCB was added
(
7
2
petroleum ether/CH Cl = 1:2) to give 0.556 g of yellow solid in
2 2
1
0% yield. Mp 253−254 °C. H NMR (400 MHz, CDCl ): δ 8.62 (s,
3
H), 7.96 (d, J = 8.0 Hz, 2H), 7.69−7.67 (m, 4H), 7.63 (d, J = 9.2
PPh
under N
3
(2.501 g, 9.54 mmol). Then, the mixture was heated to 180 °C
2
Hz, 2H), 7.60 (d, J = 7.6 Hz, 2H), 7.54 (t, J = 7.4 Hz, 2H), 4.01 (s,
for 36 h. After the reaction mixture was cooled to rt, it was
H). 13C NMR (100 MHz, CDCl ): δ 177.6, 149.0, 142.3, 135.3,
directly mixed with excess amount of silica gel powder, and then
purified by silica gel column chromatography. The first main
3
1
3
33.6, 132.7, 132.5, 131.0, 128.5, 127.3, 124.5, 122.7, 115.4, 34.0.
+
HRMS (ESI) m/z[M + H] : calcd for C H N O , 452.1246; found,
component was eluted out by an eluent of petroleum ether/CH
1:2, obtaining 0.362 g of 13 in 67% yield. The second component
was eluted out by an eluent of petroleum ether/CH Cl = 1:4,
Cl
2 2
2
6
18
3
6
=
4
52.1250.
1
0-Methyl-indolo[2,3-a]acridone (9) and 10-Methyl-indolo[3,2-
2
2
b]acridone (10). To a solution of 6 (0.425 g, 1.29 mmol) in 6 mL of
obtaining 0.052 g of 14 in 9.7% yield.
Characterization Data of 13. Mp > 300 °C. H NMR (400 MHz,
CDCl ): δ 11.61 (s, 2H), 8.44 (d, J = 9.2 Hz, 2H), 8.15 (d, J = 8.0 Hz,
2H), 7.68 (d, J = 8.0 Hz, 2H), 7.49 (t, J = 8.2 Hz, 2H), 7.46 (d, J = 9.2
1
degassed 1,2-dichlorobenzene (o-DCB) was added PPh (1.013 g,
3
3
.87 mmol). Then, the mixture was heated to 180 °C under N for 24
3
2
h. After the reaction mixture was cooled to rt, it was directly mixed
with excess amount of silica gel powder, and then purified by silica gel
column chromatography. The first main component was eluted out by
an eluent of petroleum ether/CH Cl = 1:2, obtaining 0.322 g of 9 in
1
3
Hz, 2H), 7.35 (t, J = 7.6 Hz, 2H), 4.19 (s, 3H). C NMR (100 MHz,
CDCl ): δ 126.5, 125.0, 120.1, 119.5, 111.5, 106.0, 29.7 ppm
(because of the poor solubility the C NMR spectra is incomplete).
3
1
3
2
2
+
+
8
4% yield. The second component was eluted out by pure CH Cl ,
MS (DART) m/z[M + H] : 388.1. HRMS (DART) m/z[M + H] :
calcd for C26 , 388.1444; found, 388.1439.
Characterization Data of 14. Mp > 300 °C. H NMR (400 MHz,
DMSO-d ): δ 12.23 (s, 1H), 11.58 (s, 1H), 9.22 (s, 1H), 8.55 (d, J =
2
2
obtaining 0.040 g of 10 in 10% yield.
H18ON
3
1
1
Characterization Data of 9. Mp 284−285 °C. H NMR (300
MHz, CDCl ): δ 11.51 (s, 1H), 8.65 (dd, J = 8.1, 1.5 Hz, 1H), 8.35
6
3
(
1
(
d, J = 9.0 Hz, 1H), 8.08 (d, J = 7.8 Hz, 1H), 7.76 (t(d,t,d), J = 7.8,
.5 Hz, 1H), 7.63 (d, J = 8.1 Hz, 1H), 7.61 (d, J = 8.7 Hz, 1H), 7.46
td, J = 7.7, 1.2 Hz, 1H), 7.37 (td, J = 7.4, 0.75 Hz, 1H), 7.31 (t, J =
8.8 Hz, 1H), 8.31 (d, J = 7.6 Hz, 1H), 8.18 (d, J = 7.6 Hz, 1H), 7.88
(d, J = 8.0 Hz, 1H), 7.72 (s, 1H), 7.62 (d, J = 9.2 Hz, 1H), 7.55 (d, J =
7.6 Hz, 1H), 7.47 (t, J = 7.6 Hz, 1H), 7.40 (t, J = 7.6 Hz, 1H), 7.26 (t,
1
3
13
8
.3 Hz, 1H), 7.30 (d, J = 8.7 Hz, 1H), 4.01 (s, 3H). C NMR (100
J = 7.0 Hz, 1H), 7.25 (t, J = 7.4 Hz, 1H), 4.14 (s, 3H). C NMR
MHz, CDCl ): δ 178.9, 142.1, 141.6, 139.2, 139.1, 133.3, 126.9,
(100 MHz, DMSO-d ): δ 178.0, 144.8, 142.4, 142.0, 141.7, 139.9,
6
3
1
1
26.9, 124.9, 122.9, 122.2, 121.4, 120.1, 119.4, 116.1, 115.0, 111.5,
138.6, 127.0, 126.9, 124.8, 123.0, 122.2, 121.1, 120.0, 119.8, 119.6,
118.7, 117.0, 115.7, 112.9, 111.4, 107.0, 106.9, 95.3, 35.7 ppm. MS
+
08.1, 105.5, 34.6 ppm. MS (DART) m/z[M + H] : 299.1. HRMS
+
+
+
(
DART) m/z[M + H] : calcd for C H ON , 299.1179; found,
(DART) m/z[M + H] : 388.1. HRMS (DART) m/z[M + H] : calcd
for C26 , 388.1444; found, 388.1441.
2
0
15
2
2
99.1176.
Characterization Data of 10. Mp > 300 °C. H NMR (300 MHz,
DMSO-d ): δ 11.57 (s, 1H), 9.11 (s, 1H), 8.40 (dd, J = 8.0, 1.1 Hz,
H18ON
3
1
Calculation and X-ray Structure Determination. All the
quantum chemistry calculations were carried out by using DFT or
6
42
H), 8.28 (d, J = 7.8 Hz, 1H), 7.87−7.78 (m, 2H), 7.61 (s, 1H), 7.52
TD-DFT methods by the Gaussian 09 program. All the single-
crystal X-ray determinations were carried out by a Bruker APEXII
CCD diffractometer (Mo Kα radiation). The structures were solved
1
3
7
.1, 1.5 Hz, 1H), 7.23 (t(d,s,d), J = 7.4, 1.2 Hz, 1H), 4.01 (s, 3H). C
5
0
NMR (100 MHz, DMSO-d ): δ 177.2, 145.2, 143.0, 142.2, 142.0,
by direct methods using SHELXL-2014 programs. The atomic
ellipsoids in Figures 2−4 were drawn at the 50% probability level. All
hydrogen atoms of crystals 9−13 were located in the difference
Fourier maps and refined freely, except the hydrogen atoms of the
methyl group which were geometrically added and refined using a
riding model. The hydrogen atoms of crystals 14 were geometrically
added because of the heavy crystallographic disorder. All the 9−14
6
1
1
2
2
34.0, 127.1, 126.9, 123.0, 121.4, 121.1, 120.9, 120.1, 119.8, 119.6,
+
16.5, 116.1, 111.4, 95.0, 34.6 ppm. MS (DART) m/z[M + H] :
+
99.1. HRMS (DART) m/z[M + H] : calcd for C H ON ,
2
0
15
2
99.1179; found, 299.1177.
-Bromo-10-methyl-indolo[2,3-a]acridone (11) and 7-Bromo-
0-methyl-indolo[3,2-b]acridone (12). To a solution of 7 (0.180 g,
7
1
I
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
structure data were sent to the Web of International Union of
Crystallography for checking, and the checkCIF reports concluded no
A, B level of alerts.
(6) Jurchescu, O. D.; Popinciuc, M.; van Wees, B. J.; Palstra, T. T.
M. Interface-Controlled, High-Mobility Organic Transistors. Adv.
Mater. 2007, 19, 688−692.
(7) Sundar, V. C.; Zaumseil, J.; Podzorov, V.; Menard, E.; Willett, R.
ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.joc.8b02939.
L.; Someya, T.; Gershenson, M. E.; Rogers, J. A. Elastomeric
Transistor Stamps: Reversible Probing of Charge Transport in
Organic Crystals. Science 2004, 303, 1644−1646.
■
*
S
(8) Jiang, W.; Zhou, Y.; Geng, H.; Jiang, S.; Yan, S.; Hu, W.; Wang,
Z.; Shuai, Z.; Pei, J. Solution-Processed, High-Performance Nano-
ribbon Transistors Based on Dithioperylene. J. Am. Chem. Soc. 2011,
1
H NMR of compounds 2 and 3, H NMR, 13C NMR,
1
1
(
33, 1−3.
and HRMS of compounds 4−14, X-ray crystallographic
structure data of compounds 9−14, TD-DFT calculated
spectral transition properties of 1 and 9−14, fluores-
cence spectra of 9 and 10 in various solvents,
fluorescence decay curves of 1, 9, 10, 12, 13, and 14,
fluorescence spectra of 9, 13, and 14 in films,
fluorescence spectra of 14 upon titration of CH COOH,
cyclic voltammograms of compounds 10, 11, 12, and 14,
energies and Cartesian coordinates table for compounds
9) Takahashi, Y.; Hasegawa, T.; Horiuchi, S.; Kumai, R.; Tokura,
Y.; Saito, G. High Mobility Organic Field-Effect Transistor Based on
Hexamethylenetetrathiafulvalene with Organic Metal Electrodes.
Chem. Mater. 2007, 19, 6382−6384.
(
10) Xu, X.; Yao, Y.; Shan, B.; Gu, X.; Liu, D.; Liu, J.; Xu, J.; Zhao,
2
−1 −1
N.; Hu, W.; Miao, Q. Electron Mobility Exceeding 10 cm V
s
and
3
Band-Like Charge Transport in Solution-Processed n-Channel
Organic Thin-Film Transistors. Adv. Mater. 2016, 28, 5276−5283.
(11) Briseno, A. L.; Miao, Q.; Ling, M.-M.; Reese, C.; Meng, H.;
1
and 9−14, the calculation for the intermolecular N2−
Bao, Z.; Wudl, F. Hexathiapentacene: Structure, Molecular Packing,
and Thin-Film Transistors. J. Am. Chem. Soc. 2006, 128, 15576−
15577.
H2···O1 hydrogen bond of 13, and computational
details for reorganization energies (PDF)
(12) Zhang, C.; Zang, Y.; Gann, E.; McNeill, C. R.; Zhu, X.; Di, C.;
X-ray crystal details for 9 (CIF)
X-ray crystal details for 10 (CIF)
X-ray crystal details for 11 (CIF)
X-ray crystal details for 12 (CIF)
X-ray crystal details for 13 (CIF)
X-ray crystal details for 14 (CIF)
Zhu, D. Two-Dimensional π-Expanded Quinoidal Terthiophenes
Terminated with Dicyanomethylenes as n-Type Semiconductors for
High-Performance Organic Thin-Film Transistors. J. Am. Chem. Soc.
2
(
014, 136, 16176−16184.
13) Gsanger, M.; Kirchner, E.; Stolte, M.; Burschka, C.;
Stepanenko, V.; Pflaum, J.; Wurthner, F. High-Performance Organic
Thin-Film Transistors of J-Stacked Squaraine Dyes. J. Am. Chem. Soc.
014, 136, 2351−2362.
14) Usta, H.; Risko, C.; Wang, Z.; Huang, H.; Deliomeroglu, M. K.;
̈
̈
2
(
AUTHOR INFORMATION
Corresponding Author
E-mail: fangqi@sdu.edu.cn.
■
*
Zhukhovitskiy, A.; Facchetti, A.; Marks, T. J. Design, Synthesis, and
Characterization of Ladder-Type Molecules and Polymers. Air-Stable,
Solution-Processable n-Channel and Ambipolar Semiconductors for
Thin-Film Transistors via Experiment and Theory. J. Am. Chem. Soc.
ORCID
2
(
009, 131, 5586−5608.
Qi Fang: 0000-0001-8024-2875
Notes
The authors declare no competing financial interest.
15) Dou, J.-H.; Zheng, Y.-Q.; Yao, Z.-F.; Yu, Z.-A.; Lei, T.; Shen,
X.; Luo, X.-Y.; Sun, J.; Zhang, S.-D.; Ding, Y.-F.; Han, G.; Yi, Y.;
Wang, J.-Y.; Pei, J. Fine-Tuning of Crystal Packing and Charge
Transport Properties of BDOPV Derivatives through Fluorine
Substitution. J. Am. Chem. Soc. 2015, 137, 15947−15956.
ACKNOWLEDGMENTS
■
(
16) Jiang, W.; Li, Y.; Wang, Z. Tailor-Made Rylene Arrays for High
Performance n-Channel Semiconductors. Acc. Chem. Res. 2014, 47,
135−3147.
17) Xiong, Y.; Qiao, X.; Wu, H.; Huang, Q.; Wu, Q.; Li, J.; Gao, X.;
This work was supported by the National Natural Science
Foundation of China (Grant Nos. 21472116 and 21871165)
and the State Key Laboratory of Crystal Materials. The authors
thank Professor Zhi-qiang Liu for the discussions about the
synthesis methods, Professor Hong Lei for the mobility
calculation, and Professor Lei Ji and Dr. Ye Fang for assistance
in editing the text of this manuscript.
3
(
Li, H. Syntheses and Properties of Nine-Ring-Fused Linear
Thienoacenes. J. Org. Chem. 2014, 79, 1138−1144.
(18) Marcus, R. A. Electron transfer reactions in chemistry. Theory
and experiment. Rev. Mod. Phys. 1993, 65, 599−610.
(19) Balzani, V.; Juris, A.; Venturi, M.; Campagna, S.; Serroni, S.
REFERENCES
Luminescent and Redox-Active Polynuclear Transition Metal
■
Complexes. Chem. Rev. 1996, 96, 759−833.
(
1) Tsumura, A.; Koezuka, H.; Ando, T. Macromolecular electronic
device: Field-effect transistor with a polythiophene thin film. Appl.
Phys. Lett. 1986, 49, 1210−1212.
2) Wang, C.; Dong, H.; Hu, W.; Liu, Y.; Zhu, D. Semiconducting π-
Conjugated Systems in Field-Effect Transistors: A Material Odyssey
of Organic Electronics. Chem. Rev. 2012, 112, 2208−2267.
3) Mei, J.; Diao, Y.; Appleton, A. L.; Fang, L.; Bao, Z. Integrated
Materials Design of Organic Semiconductors for Field-Effect
Transistors. J. Am. Chem. Soc. 2013, 135, 6724−6746.
4) Mas-Torrent, M.; Rovira, C. Role of Molecular Order and Solid-
State Structure in Organic Field-Effect Transistors. Chem. Rev. 2011,
11, 4833−4856.
5) Takimiya, K.; Shinamura, S.; Osaka, I.; Miyazaki, E.
Thienoacene-Based Organic Semiconductors. Adv. Mater. 2011, 23,
347−4370.
(20) Fang, Q.; Chen, H.; Lei, H.; Xue, G.; Chen, X. Full-capped 12-
S-atom TTP derivatives (BV-TTP, BE-TTP, EM-TTP and EV-TTP):
syntheses, structures and charge transport properties. CrystEngComm
(
2
(
015, 17, 787−796.
21) Li, R.; Jiang, L.; Meng, Q.; Gao, J.; Li, H.; Tang, Q.; He, M.;
Hu, W.; Liu, Y.; Zhu, D. Micrometer-Sized Organic Single Crystals,
Anisotropic Transport, and Field-Effect Transistors of a Fused-Ring
Thienoacene. Adv. Mater. 2009, 21, 4492−4495.
(
(
(22) Okamoto, T.; Kudoh, K.; Wakamiya, A.; Yamaguchi, S. General
Synthesis of Thiophene and Selenophene-Based Heteroacenes. Org.
Lett. 2005, 7, 5301−5304.
1
(
(23) Okamoto, T.; Mitsui, C.; Yamagishi, M.; Nakahara, K.; Soeda,
J.; Hirose, Y.; Miwa, K.; Sato, H.; Yamano, A.; Matsushita, T.;
Uemura, T.; Takeya, J. V-Shaped Organic Semiconductors With
4
J
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
Solution Processability, High Mobility, and High Thermal Durability.
(42) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.;
Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.;
Montgomery, J. A.; Peralta, J. E., Jr.; Ogliaro, F.; Bearpark, M.;
Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi,
R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar,
S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox,
J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.;
Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.;
Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A.
D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J.
Gaussian 09, revision A.02; Gaussian, Inc.: Wallingford, CT, 2009.
(43) Paulus, E. F.; Leusen, F. J. J.; Schmidt, M. U. Crystal structures
of quinacridones. CrystEngComm 2007, 9, 131−143.
Adv. Mater. 2013, 25, 6392−6397.
(24) Rieger, R.; Beckmann, D.; Mavrinskiy, A.; Kastler, M.; Mullen,
̈
K. Backbone Curvature in Polythiophenes. Chem. Mater. 2010, 22,
314−5318.
25) Laquindanum, J. G.; Katz, H. E.; Lovinger, A. J. Synthesis,
5
(
Morphology, and Field-Effect Mobility of Anthradithiophenes. J. Am.
Chem. Soc. 1998, 120, 664−672.
(
26) Mamada, M.; Katagiri, H.; Mizukami, M.; Honda, K.;
Minamiki, T.; Teraoka, R.; Uemura, T.; Tokito, S. syn-/anti-
Anthradithiophene Derivative Isomer Effects on Semiconducting
Properties. ACS Appl. Mater. Interfaces 2013, 5, 9670−9677.
(27) Niimi, K.; Shinamura, S.; Osaka, I.; Miyazaki, E.; Takimiya, K.
Dianthra[2,3-b:2′,3′-f ]thieno[3,2-b]thiophene (DATT): Synthesis,
Characterization, and FET Characteristics of New π-Extended
Heteroarene with Eight Fused Aromatic Rings. J. Am. Chem. Soc.
2
(
011, 133, 8732−8739.
28) Yamamoto, K.; Higashibayashi, S. Synthesis of Three-
(44) Mei, X.; Wolf, C. Crystallization through Slow Acid-Controlled
Dimensional Butterfly Slit-Cyclobisazaanthracenes and Hydrazinobi-
santhenes through One-Step Cyclodimerization and Their Properties.
Chem. - Eur. J. 2016, 22, 663−671.
Hydrolytic Release of a Highly Polar Organic Compound: Formation
of a Dipolar Acridone Polymorph. Cryst. Growth Des. 2005, 5, 1667−
1
670.
(29) Mamada, M.; Inada, K.; Komino, T.; Potscavage, W. J., Jr.;
(
45) Dzyabchenko, A. V.; Zavodnik, V. E.; Bel’skii, V. K.
Kristallografiya 1980, 25, 72.
46) Rovira, C.; Veciana, J.; Santalo,
Nakanotani, H.; Adachi, C. Highly Efficient Thermally Activated
Delayed Fluorescence from an Excited-State Intramolecular Proton
Transfer System. ACS Cent. Sci. 2017, 3, 769−777.
(
N.; Tarres, J.; Cirujeda, J.;
́ ́
Molins, E.; Llorca, J.; Espinosa, E. Synthesis of Several Isomeric
Tetrathiafulvalene π-Electron Donors with Peripheral Sulfur Atoms. A
Study of Their Radical Cations. J. Org. Chem. 1994, 59, 3307−3313.
(30) Chen, W.; Tian, K.; Song, X.; Zhang, Z.; Ye, K.; Yu, G.; Wang,
Y. Large π-Conjugated Quinacridone Derivatives: Syntheses,
Characterizations, Emission, and Charge Transport Properties. Org.
Lett. 2015, 17, 6146−6149.
(47) You, J.; Zhao, H.; Sun, Z.; Xia, L.; Yan, T.; Suo, Y.; Li, Y.
Application of 10-ethyl-acridine-3-sulfonyl chloride for HPLC
determination of aliphatic amines in environmental water using
fluorescence and APCI-MS. J. Sep. Sci. 2009, 32, 1351−1362.
(
31) Głowacki, E. D.; Irimia-Vladu, M.; Kaltenbrunner, M.;
Ga ş iorowski, J.; White, M. S.; Monkowius, U.; Romanazzi, G.;
Suranna, G. P.; Mastrorilli, P.; Sekitani, T.; Bauer, S.; Someya, T.;
Torsi, L.; Sariciftci, N. S. Hydrogen-Bonded Semiconducting
Pigments for Air-Stable Field-Effect Transistors. Adv. Mater. 2013,
(48) Huang, P.-C.; Parthasarathy, K.; Cheng, C.-H. Copper-
Catalyzed Intramolecular Oxidative C-H Functionalization and C-N
Formation of 2-Aminobenzophenones: Unusual Pseudo-1,2-Shift of
the Substituent on the Aryl Ring. Chem. - Eur. J. 2013, 19, 460−464.
2
(
5, 1563−1569.
32) Chen, D.-M.; Qin, Q.; Sun, Z.-B.; Peng, Q.; Zhao, C.-H.
Synthesis and properties of B,N-bridged p-terphenyls. Chem. Commun.
014, 50, 782−784.
33) Kim, H.; Kim, B.; Kim, Y.; Kim, C.; Shin, C.; Lee, S.; Yu, E.;
(49) Sharma, B. K.; Shaikh, A. M.; Agarwal, N.; Kamble, R. M.
Synthesis, photophysical and electrochemical studies of acridone-
2
(
amine based donor−acceptors for hole transport materials. RSC Adv.
2
(
016, 6, 17129−17137.
Choi, B.; Hwang, K. Condensed cyclic compound and organic light-
emitting device. European Patent EP2894157A1, July 15, 2015.
50) Sheldrick, G. M. Crystal structure refinement with SHELXL.
Acta Crystallogr., Sect. C: Struct. Chem. 2015, C71, 3−8.
(
34) Kwon, J. E.; Park, S. Y. Advanced Organic Optoelectronic
Materials: Harnessing Excited-State Intramolecular Proton Transfer
ESIPT) Process. Adv. Mater. 2011, 23, 3615−3642.
35) Demchenko, A. P.; Tang, K.-C.; Chou, P.-T. Excited-state
(
(
proton coupled charge transfer modulated by molecular structure and
media polarization. Chem. Soc. Rev. 2013, 42, 1379−1408.
(36) Zhang, Z.; Chen, Y.-A.; Hung, W.-Y.; Tang, W.-F.; Hsu, Y.-H.;
Chen, C.-L.; Meng, F.-Y.; Chou, P.-T. Control of the Reversibility of
Excited-State Intramolecular Proton Transfer (ESIPT) Reaction:
Host-Polarity Tuning White Organic Light Emitting Diode on a New
Thiazolo[5,4-d]thiazole ESIPT System. Chem. Mater. 2016, 28,
8
(
815−8824.
37) Thelakkat, M.; Schmidt, H.-W. Synthesis and Properties of
Novel Derivatives of 1,3,5-Tris(diarylamino)benzenes for Electro-
luminescent Devices. Adv. Mater. 1998, 10, 219−223.
(38) Schweicher, G.; Olivier, Y.; Lemaur, V.; Geerts, Y. H. What
Currently Limits Charge Carrier Mobility in Crystals of Molecular
Semiconductors? Isr. J. Chem. 2014, 54, 595−620.
(39) Berlin, Y. A.; Hutchison, G. R.; Rempala, P.; Ratner, M. A.;
Michl, J. Charge Hopping in Molecular Wires as a Sequence of
Electron-Transfer Reactions. J. Phys. Chem. A 2003, 107, 3970−3980.
(40) Vaissier, V.; Frost, J. M.; Barnes, P. R. F.; Nelson, J. Influence of
Intermolecular Interactions on the Reorganization Energy of Charge
Transfer between Surface-Attached Dye Molecules. J. Phys. Chem. C
2
(
015, 119, 24337−24341.
41) Deng, W.-Q.; Goddard, W. A., III Predictions of Hole
Mobilities in Oligoacene Organic Semiconductors from Quantum
Mechanical Calculations. J. Phys. Chem. B 2004, 108, 8614−8621.
K
DOI: 10.1021/acs.joc.8b02939
J. Org. Chem. XXXX, XXX, XXX−XXX