Syntheses of polycyclic aromatic diimides via intramolecular cyclization of maleic acid derivatives

Article abstract of DOI:10.1039/c5nj01849h

Using readily available aryl glyoxylic acids and arylene diacetic acids as starting materials, a series of polycyclic aromatic molecules bearing two phthalimide functional groups are synthesized via Perkin condensation followed by intramolecular cyclizati

Full text of DOI:10.1039/c5nj01849h

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Syntheses of polycyclic aromatic diimides via
intramolecular cyclization of maleic acid
Cite this:DOI: 10.1039/c5nj01849h
derivatives†
Ranran Wang, Ke Shi, Kang Cai, Yikun Guo, Xiao Yang, Jie-Yu Wang, Jian Pei* and
Dahui Zhao*
Using readily available aryl glyoxylic acids and arylene diacetic acids as starting materials, a series of
polycyclic aromatic molecules bearing two phthalimide functional groups are synthesized via Perkin
condensation followed by intramolecular cyclization reactions. Two different cyclization methods, photo-
oxidation and Heck cross-coupling, are employed, both of which effectively accomplish the transformations
from diaryl maleic anhydride or maleimide to polycyclic aromatic phthalimide functionality. The
photocyclization protocol conveniently allows direct bridging of two plain aromatic C–H sites linked by
a maleic anhydride group and uniquely produces the more twisted polycyclic framework as the major
product, whereas the Heck coupling approach can typically afford more extended polycyclic skeletons.
Thionation reactions are then carried out for the obtained polycyclic diimide molecules using Lawesson’s
reagent. For all isolated stable products, partial thionation occurs. The prepared polycyclic diimide
compounds possess relatively low LUMO levels, and thionation further decreases the LUMO energy of
the molecules by 0.2–0.3 eV. Electron-transporting properties are characterized by using solution-
processed OFET devices, and an electron mobility of 0.054 cm2 Vꢀ1 sꢀ1 is demonstrated by a selected
compound. Such semiconducting performance promises great potentials of this class of compounds
as useful electron-accepting and transporting building blocks in developing various new semi-
conductive materials.
Received (in Montpellier, France)
15th July 2015,
Accepted 13th October 2015
DOI: 10.1039/c5nj01849h
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of such versatile and attractive properties, we deem that more
diverse PAI structures should be designed and examined.
Introduction
Polycyclic aromatic dicarboximide (PAI) compounds have demon- Compared to PAI structures functionalized with 6-membered-ring
strated prominent potentials for applications in organic electro- dicarboximide units, analogous molecules featuring 5-membered-
nics.1 Amongst various PAI molecules, naphthalene and perylene ring phthalimide-type groups are less reported and studied.
diimides are the most intensively studied n-type semiconductors.2,3 Recently, a number of polycyclic aromatics bearing phthalimide
Recently, impressive research progress has also been made moieties has been prepared and their optical properties are
with PAIs being used as electron-accepting materials in organic carefully investigated,6 but the semiconducting potentials of
solar cells.4 Moreover, the unique self-assembly propensity and PAI systems still await exploration.
supramolecular architectures of PAIs have attracted great interest
Here, we report the syntheses and properties of a series of
in the field of supramolecular chemistry. PAI derivatives are also polycyclic aromatic molecules bearing phthalimide functional
utilized for developing novel low-band-gap dyes.5 Apparently, groups, which are potentially suitable building blocks of new
all these appealing applications of PAIs are dependent on the electron-accepting or transporting materials. Specifically, eight
electron-deficient and low-LUMO (lowest unoccupied molecular different PAI compounds are obtained, each containing 5 to
orbital) attributes of the polycyclic aromatic systems installed 7 fused benzene rings decorated with two phthalimide units
with multiple electron-withdrawing dicarboximide groups. In view (Chart 1). Among various available synthetic strategies,7 we
select Perkin condensation to assemble a series of different
National Laboratory for Molecular Sciences, Centre for Soft Matter Science and
diaryl maleic anhydrides, which serve as effectual precursors to
the target PAI molecules. Great merits of Perkin condensation are
its facile synthetic procedures and readily available substrates.
Engineering and the Key Laboratory of Polymer Chemistry and Physics of the
Ministry of Education, College of Chemistry, Peking University, Beijing 100871,
China. E-mail: dhzhao@pku.edu.cn, jianpei@pku.edu.cn
The starting materials used in the current work are phenyl and
naphthyl glyoxylic acids along with various arylene diacetic acids.
† Electronic supplementary information (ESI) available: Complete synthetic
details, NMR spectra and DFT calculation results. See DOI: 10.1039/c5nj01849h
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Scheme 2 Thionation reaction results.
Chart 1 Synthesized polycyclic aromatic diimide compounds and their
thionation derivatives.
characterization shows that these PAI molecules possess relatively
low LUMO levels at ꢀ3.4 to ꢀ3.7 eV. As an effort to further lower
the LUMO levels, thionation of the carbonyl groups is then carried
out for the PAI compounds using Lawesson’s reagent (Scheme 2).
Interestingly, for all isolated stable products, partial yet regio-
selective thionation occurs. That is, only one of the two carbonyl
groups in every dicarboximide unit gets thionated (Chart 1).
Compared to their oxo-counterparts, these thio-substituted PAI
derivatives exhibit further decreased LUMO energy levels at ꢀ3.8
to ꢀ3.9 eV. Subsequently, for molecules suitable for fabricating
solution-processed organic field effect transistors (OFETs), the
electron-transporting ability is evaluated. An electron mobility of
0.054 cm2 Vꢀ1 sꢀ1 is determined for one of the PAI molecules.
Such semiconducting properties promise this class of compounds
as potentially useful subunits for developing new electron-
accepting and transporting (polymer) materials.
Two annulation methods, the intramolecular Heck coupling8
and photo-oxidation cyclization,9–11 are employed to accomplish
different polycyclic aromatic scaffolds (Scheme 1). In all the
prepared PAIs, branched alkyl side groups are attached to the
imide nitrogen atoms, which help in ensuring adequate solubility
of the products in common organic solvents.3,4,12 Electrochemical
Results and discussion
PAI syntheses
Using phenylglyoxylic acid to react with 2,20-(1,4-phenylene)-
and 2,20-(1,3-phenylene)diacetic acids, respectively, regio-isomeric
molecules 9 and 10 of bis-maleic anhydride were obtained through
Perkin condensation in neat acetic anhydride (Scheme 1). Sub-
sequently, intramolecular cyclization was attempted under
photo-oxidation conditions. The reaction mixture, containing the
bis-maleic anhydride dissolved in mixed acetone and propylene
oxide (PO) along with iodine, was irradiated using a high-pressure
mercury lamp at room temperature under a nitrogen atmo-
sphere.9,10 The resultant cyclized dianhydrides were poorly
soluble in most organic solvents and thus directly applied to the
subsequent imidization step. Upon reacting with 2-octyldodecan-1-
amine in refluxing N-methyl-2-pyrrolidone (NMP), the dianhydrides
were transformed into corresponding polycyclic aromatic diimides,
showing reasonably good solubility.
Upon further examination, the final PAI products derived
from dianhydride 9 were a mixture of two different molecules,
regio-isomers 1 and 2, which could be separated and character-
ized respectively. Although the 1H NMR spectra offered certain
evidence for differentiating 1 and 2, unambiguous structural
Scheme 1 Synthetic routes towards diimides 1–8.
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identifications were realized only after isomer 2 was indepen- acid and 1-naphthylglyoxylic acid. As expected, PAI 7 was
dently prepared via a different synthetic route (Scheme 1). In formed as the major product, with a minimal byproduct of
this alternative pathway, 2,20-(2,5-dibromo-1,4-phenylene)diacetic isomer 8. Evidently, the same regio-selectivity was manifested
acid was subjected to Perkin condensation conditions and here as in the reaction generating PAI 1. Meanwhile, following
coupled with two equivalents of phenylglyoxylic acid, affording the route of Perkin condensation, imidization, and Heck
a dibromo-substituted bis-maleic anhydride. Imidization was coupling, PAI 8 was obtainable in a more favorable yield from
then carried out and offered intermediate 11 with improved dianhydride intermediate 15, prepared from 2,5-dibromo-
solubility, which allowed proper conduction of subsequent intra- 1,4-phenylenediacetic acid and 1-naphthylglyoxylic acid as the
molecular Heck cross coupling,8 yielding exclusively diimide 2.
After identifying the structures of 2, the helicene-type isomer
1 was found to be the major product from the photo-oxidation
substrates.
Thionation reactions
reaction, along with byproduct diimide 2 having a relatively As an effort to further lower the LUMO of the prepared PAIs,14
extended polycyclic skeleton formed in o5% yield. Such a thionation reactions were carried out using Lawesson’s reagent
regio-selectivity of the photocyclization protocol was consistent (Scheme 2). However, it was found that the thionation products
with the results previously reported by Frimer et al.10 On the from a number of studied PAI compounds were unstable and
other hand, with an overall yield of 440% over three steps, the decomposed during the reaction. Stable thionation products
route harnessing the Heck coupling was apparently a more were only achieved from compounds 6, 7 and 8, and these
favorable synthetic path for PAI 2, although it required the pre- isolated thionation derivatives, 6-S, 7-S and 8-S, appeared as well
installation of bromine atoms at specific positions. Nonethe- sensitive to moisture and displayed a tendency to decompose
less, the photocyclization method uniquely generated diimide 1 gradually under ambient conditions. Additionally, the mass
with a helicene-type scaffold, which was difficult to attain from spectroscopy characterization revealed that 6-S, 7-S and 8-S all
alternative approaches.
contained only two sulfur atoms, instead of four as expected.
When similar photocyclization procedures followed by an Furthermore, the H and 13C NMR spectra of these compounds
imidization process were applied to bis-maleic anhydride 10, indicated that such partial thionation products displayed similar
again a pair of regio-isomer PAI products was produced. Distinct molecular symmetry to that of their respective synthetic pre-
1H NMR spectra clearly identified and differentiated 3 and 4, cursors of oxo-analogues. Hence, although we could not obtain
because 3 had an asymmetric polycyclic backbone, while 4 featured unambiguous evidence to identify the exact structures of 6-S, 7-S
a mirror-plane symmetry. Moreover, PAI 3 was found to be the and 8-S, regarding the specific locations of sulfur atoms, it was
major component in the final product mixture, indicating that confirmable that one of the two carbonyl oxygen atoms in all
the main product yielded from photocyclization of 10 was the dicarboximide functional groups was converted to a sulfur atom
asymmetric dianhydride structure.9,10 This result was also in in a site-selective fashion (Chart 1).
1
accordance with previous observations made with photocyclization
of 1,3-distyrylbenzene derivatives.13 From the above results, it was
Photophysical and electrochemical characterization
clear that such photo-induced oxidative couplings preferentially Subsequently, all PAI molecules were subjected to electronic
happened to arene C–H sites with two ortho-substitutions.10,13
property characterization, with the absorption properties examined
To further explore the substrate scope of the photocycliza- first. For PAIs 1–7, the main absorption bands occurred between
tion protocol, we then used naphthylenediacetic acids as the 300 and 500 nm (Fig. 1), whereas compound 8 exhibited an
central moiety to prepare PAI molecules with larger aromatic additional peak of much longer wavelength at over 500 nm.
skeletons. When 2,20-(naphthalene-2,6-diyl)diacetic acid was Compared to their oxo-counterparts, the absorption of thionated
employed as a reactant to couple with phenylglyoxylic acid, compounds 6-S, 7-S and 8-S was considerably red-shifted (Fig. 2).
only diimide 5 was isolated upon a series of reactions including Based on the onset of the absorption band, the optical band gap
Perkin condensation, photocyclization and imidization. No other (Eg) of 6-S, 7-S and 8-S was narrowed by 0.58, 0.45 and 0.38 eV,
regio-isomer involving photo-cyclization on the b-positions of respectively, relative to those of 6, 7 and 8 (Table 1).
naphthylene was detected. This result was not surprising since
Most of the prepared PAI molecules were moderately fluores-
the a-position of naphthalene was commonly more reactive than cent (Fig. 3), showing fluorescence quantum yields ranging
the b-position. When phenylglyoxylic acid was subjected to reac- from 0.10 to 0.25 (Table 1).15 Nonetheless, the F value of 3
tion with 2,20-(naphthalene-1,5-diyl)diacetic acid, PAI 6 was (B0.01) was significantly lower than those of other PAIs, which
formed as the only product after photocyclization and imidiza- was likely a result from its twisted polycyclic backbone. The
tion procedures. It is noteworthy that a prolonged irradiation steric hindrance between the imide carbonyl and the aromatic
time was necessary for the 1,5-naphthylene-derived substrate backbone possibly caused additional non-radiative decay in the
13 than corresponding 2,6-substituted analogue 12. Presum- excited state of 3. All three thionated compounds 6-S, 7-S and
ably this was also because the reactivity of the b-positions of 8-S were nearly non-fluorescent, reflecting a significant emission
naphthalene was much lower compared to the a-positions in quenching effect of the sulfur atoms.
the photocyclization.
In subsequent electrochemical characterization, PAIs 1–8 all
We then employed another dianhydride substrate 14, which was showed two reversible reductive waves in their cyclic voltammo-
obtained from Perkin condensation between 1,4-phenylenediacetic grams (CVs) (Fig. 4).16 Estimated from the potential onset of the
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Table 1 Optical and frontier orbital data
Fa
0.10
0.21
0.01
0.25
0.15
0.21
0.15
Egb/eV
LUMOc/eV
HOMOd/eV
1
2
3
4
5
6
7
8
2.64
2.50
2.66
2.63
2.51
2.58
2.44
2.23
2.00
1.99
1.85
ꢀ3.51
ꢀ3.56
ꢀ3.41
ꢀ3.49
ꢀ3.41
ꢀ3.40
ꢀ3.54
ꢀ3.67
ꢀ3.76
ꢀ3.83
ꢀ3.90
ꢀ6.15
ꢀ6.06
ꢀ6.07
ꢀ6.12
ꢀ5.92
ꢀ5.98
ꢀ5.98
ꢀ5.90
ꢀ5.76
ꢀ5.82
ꢀ5.75
0.14
6-S
7-S
8-S
o0.01
o0.01
o0.01
a
b
Fluorescence quantum yields measured in chloroform. Band gap
values estimated from the absorption onset. From the onset of the
first reduction wave in CV. Calculated from Eg and the LUMO.
c
d
Fig. 1 Absorption spectra of PAI 1–8 in CHCl3 (1 ꢁ 10ꢀ5 M).
Fig. 3 Fluorescence emission spectra of PAI 1–8 (1 ꢁ 10ꢀ6 M, excited
at 410 nm).
Fig. 2 Absorption spectra of 6-S, 7-S and 8-S in CHCl3 (1 ꢁ 10ꢀ5 M).
confirmed by density functional theory (DFT) calculations, which
first reduction peaks, the LUMO energy levels of 1–7 were all in revealed that molecule 3 had a non-planar polycyclic backbone
the range of ꢀ3.40 to ꢀ3.56 eV, while PAI 8 exhibited a lower due to the steric interference between one of the terminal
LUMO at ꢀ3.67 eV (Table 1). Specifically, among regio-isomers benzene rings and a nearby imide carbonyl group (Fig. S1, ESI†).
1–4, PAI 2 having an extended benzo[k]tetraphene-5,6,12,13- As a result, the LUMO of 3 was localized to part of the polycyclic
tetracarboxydiimide backbone displayed the lowest LUMO level backbone, covering only one of the two dicarboximide moieties.
and the narrowest band gap, whereas molecule 3 featuring In contrast, the LUMOs of all other three isomers were delocalized
an asymmetric benzo[c]chrysene-1,2,7,8-tetracarboxydiimide dis- over the entire polycyclic scaffolds.
played the highest LUMO and the most widened band gap. Such
With additional benzene rings fused to the polycyclic frame-
electronic properties of 3 could as well be related to its twisted works, the HOMO levels of 5–8 were noticeably boosted relative
polycyclic framework, which frustrated electron delocalization to those of 1–4 (Table 1). While regio-isomers 5 and 6 possessed
over the conjugated aromatic skeleton. This assumption was similar LUMOs at ꢀ3.4 eV, much lowered LUMOs were detected
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Fig. 4 Cyclic voltammograms of 1–8, 6-S, 7-S and 8-S in CH2Cl2.
Fig. 5 Top- and side-views of optimized geometry of possible structures
of 6-S, 7-S and 8-S.
with 7 and 8. Particularly, compound 8 manifested the lowest
LUMO at ꢀ3.67 eV among all herein studied PAIs.
Partial thionation of the dicarboximide groups brought
about conspicuous decrease in the LUMO levels of these poly-
cyclic diimide molecules. According to the CV data, the LUMOs
of 6-S, 7-S and 8-S were all lowered by 0.2 to 0.3 eV relative to
their respective oxo- analogues 6–8. Such a pronounced effect of
carbonyl thionation was also consistent with the DFT calculation
results, which showed that thiocarbonyl moieties made substan-
tial contributions to the LUMOs of the molecules (Fig. S2, ESI†).
OFET characterization
Subsequently, the semiconducting properties of these PAIs and
their thionation derivatives were subjected to examination in
OFET devices using the solution-processing technique. The
devices were fabricated with the top-gate/bottom-contact (TG-BC)
configuration, which has proven more suitable for characterizing
solution-processed electron-transporting semiconductors. During
the device fabrication, a CYTOP dielectric layer was necessarily
introduced on the top of the semiconductive layer and was
baked at 100 1C. Organic molecules having low melting points
near or below 100 1C were thus not suitable for such device
characterization. Unfortunately, most PAI molecules synthe-
sized in this work exhibited relatively low melting points and
hence could not be characterized, except for 2 and 8. It is
particularly noteworthy that thionated derivatives 6-S, 7-S and
8-S surprisingly possessed lower melting points than their oxo-
counterparts. We suspect that such properties were related to the
steric characteristics of the molecules. That is, although sulfur
atoms induce larger van der Waals interactions, the larger size of
the atom entails greater distortion and non-planarity of the
polycyclic skeletons. The DFT calculation results were consistent
with such a proposition, showing nonplanar geometry of the
Fig. 6 The transfer (a) and output (b) profiles of 8 measured in solution-
processed OFET under ambient conditions.
solution processing conditions, rendering them unsuitable for
solution-processed OFET characterization. An electron mobility
of B10ꢀ3 cm2 Vꢀ1 sꢀ1 was observed for PAI 2. Such a mobility
value most likely suffered from the high tendency of compound
2 to crystallize under the device fabrication conditions, since
discontinuous crystalline domains were perceivable with the
semiconductive layer. Atomic force microscopy (AFM) and X-ray
diffraction (XRD) provided supportive evidence for the high
crystallinity of 2 in the thin-film state (Fig. S3 and S4, ESI†). In
comparison, PAI 8 exhibiting a suitable melting point and more
favorable film morphology displayed a much more desirable
electron mobility of 0.054 cm2 Vꢀ1 sꢀ1 under ambient condi-
tions (Fig. 6).
Conclusions
optimized structures of 6-S, 7-S and 8-S (Fig. 5). Such nonplanar In summary, using readily available aryl glyoxylic and arylene
structures could apparently preclude very compact molecular diacetic acids as reactants, we synthesize eight different poly-
packing and cause lowering of the melting points.
cyclic aromatic tetracarboxydiimide derivatives via facile Perkin
In addition to the melting points, the device performance of condensation followed by photo-oxidation or intramolecular
solution-processed semiconductors was also sensitive to the Heck cross-coupling reactions. Each of these PAI molecules
crystallinity of the active materials. Most of the prepared PAI contains 5 to 7 fused benzene rings bearing two phthalimide-
molecules exhibited evident tendency to crystallize under type functional groups at varied positions. The two employed
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cyclization methods, photo-oxidation and Heck cross-coupling, The absorption spectra were recorded on a Hitachi U-4100
are both effective in accomplishing the functional group trans- spectrophotometer using a 1 cm quartz cell at 298 K. The
formation from diaryl maleic anhydride to polycyclic phthal- emission spectra were recorded on a Perkin Elmer LS55 Lumines-
imide. The advantage of the photocyclization method lies in the cence Spectrometer at 298 K. The emission quantum yields (F)
fact that it conveniently allows direct bridging of two plain C–H were measured at 10ꢀ6 M in chloroform at 298 K using perylene as
sites on properly linked aromatic rings. Moreover, the photo- the standard for 1–7 and perylene orange as the standard for 8.15
oxidation procedure uniquely produces the more twisted poly- Cyclic voltammetry (CV) was recorded using a BASI Epsilon
cyclic skeletons as the major products, which are difficult to workstation and the measurements were carried out at 298 K in
attain from alternative procedures such as Heck cross-coupling. CH2Cl2 containing 0.1 M n-Bu4NPF6 as the supporting electrolyte.
On the other hand, the Heck protocol offers higher overall A glassy carbon electrode was used as the working electrode, with
reaction yields and better control at the product structures. In a platinum sheet as the counter electrode. All potentials were
light of such distinct regio-chemistry features, both approaches recorded with Ag/AgCl as the reference electrode, at a scan speed
represent valuable synthetic methods that complement each of 50 mV sꢀ1. Ferrocene/ferrocenium was employed as an external
other. Furthermore, using Lawesson’s reagent thionation reac- reference, the energy level of which is assumed to be ꢀ4.8 eV
tions are performed to obtain PAIs. For unclear reasons, some below the vacuum level.16 The LUMO levels were estimated from
thionated products are unstable. For those isolated, stable the onset potentials of the first reduction waves in CV.
products, partial thionation occurs, resulting in regio-selective
Device fabrication and characterization
substitution of one of the two oxygen atoms in every dicarbox-
imide functionality.
Top-gate/bottom-contact FET devices were fabricated using
Owing to the electron-withdrawing effect of the dicarboximide n++-Si/SiO2 (300 nm) substrates. The gold source and drain
groups, all the prepared polycyclic aromatic dicarboximide mole- bottom electrodes (with Ti as the adhesion layer) were pat-
cules show relatively low LUMOs at ꢀ3.4 to ꢀ3.7 eV, and the terned by photolithography on the SiO2 surface. The substrates
LUMOs of partially thionated molecules are typically further were subjected to cleaning using ultrasonication in acetone,
lowered by 0.2 to 0.3 eV relative to their respective oxo- analogues. the cleaning agent, deionized water (twice), and isopropanol.
An electron mobility of 0.054 cm2 Vꢀ1 sꢀ1 is observed in a The cleaned substrates were dried under vacuum at 80 1C for
solution-processed field effect transistor with a selected structure 2 h and then transferred into a glovebox. The semiconductive
8 having suitable melting point and film morphology. Such layer was deposited on the treated substrates by spin-coating tri-
semiconductive performance demonstrates great promise of this chloroethylene solutions of respective compounds (at 10 mg mlꢀ1
)
class of compounds as useful electron-accepting and transporting at 1800 rpm for 60 s. A CYTOP solution (CTL809M : CT-solv180 =
building blocks in developing new semiconductive materials. The 3 : 1) was spin-coated onto the semiconducting layer at 2000 rpm
thionated derivatives with lower LUMOs are especially attractive for 60 s, resulting in a thick dielectric layer of 500 nm, which was
subunit structures.
then baked at 100 1C for 1 h. Gate electrodes of Al (50 nm thick)
were then thermally evaporated through a shadow mask onto
the dielectric layer. The OFET devices had a channel length (L)
of 5 mm and a channel width (W) of 200 mm. The evaluations of
the FETs were carried out under ambient conditions (humidity
50–60%) on a probe stage using a Keithley 4200 SCS as the
Experimental section
Materials and methods
All chemicals were obtained from commercial sources and used parameter analyzer. The carrier mobility, m, was calculated from
as received unless otherwise indicated. 2,20-(2,5-Dibromo-1,4- the data in the saturated regime according to the equation
phenylene)diacetic acid,6 2,20-(naphthalene-1,5-diyl)diacetic ISD = (W/2L)Cim(VG ꢀ VT)2, where ISD is the drain current in the
acid,17 2-(naphthalen-1-yl)-2-oxoacetic acid18 and compound saturated regime. W and L are the semiconductor channel
99,10 were prepared according to the reported methods, and width and length, respectively. Ci (Ci = 3.7 nF) is the capacitance
1
their structures were confirmed with H NMR spectra. Photo- per unit area of the gate dielectric layer. VG and VT are the gate
cyclization was carried out under a nitrogen atmosphere using voltage and threshold voltage, respectively. VG ꢀ VT of the device
1
a CEL-LAM500 high-pressure mercury lamp. H and 13C NMR was determined from the relationship between the square root of
spectra were recorded at 298 K on a Varian Mercury plus 300 ISD and VG at the saturated regime.
(300 MHz) or a Bruker Avance 400 (400 MHz) in CDCl3 or
otherwise noted solvent. Chemical shifts are reported in parts
General synthesis procedures for PAIs
per million (ppm) with tetramethylsilane (TMS, 0 ppm) as the
General procedures for photocyclization. A photochemical
reference for 1H NMR spectra and CDCl3 (77.0 ppm) as the reactor containing dianhydride (9, 10, 12, 13 or 14) (1.0 equiv.),
reference for 13C NMR spectra, unless noted otherwise. High- I2 (2.2 equiv.), acetone (or tetrahydrofuran), and propylene
resolution ESI mass spectra (HR-ESI MS) were recorded on a oxide (PO) was flushed with N2 for 10 min and sealed. The
Bruker Apex IV Fourier transformation mass spectrometer. reddish brown solution was irradiated with a high-pressure
Elemental analyses were performed using a German Vario EL mercury light at room temperature for several hours. The
CUBE elemental analyzer. Melting points were acquired through mixture was then concentrated and filtered to give a dull yellow
a Q100DSC modulation differential scanning calorimeter. powder mixture, which was dried in an oven and then mixed
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with 2-octyldodecan-1-amine (2.0 equiv.) in NMP. The suspen- 123.9, 123.0, 116.7, 42.4, 37.2, 31.9, 31.6, 30.1, 29.9, 29.7, 29.3,
sion was subsequently heated at reflux overnight. The cooled 26.5, 22.7, 14.1. HR-ESI MS: calcd for C66H93N2O4 (M + H+):
mixture was poured into water and extracted with CH2Cl2. The 977.7130; found: 977.7152. Calcd for C66H92N2O4: C, 81.10%;
organic layers were combined and dried over anhydrous Na2SO4 H, 9.49%; N, 2.87%; found: C, 80.99%; H, 9.52%; N, 2.83%.
before the solvents were removed under reduced pressure. The m.p.: 86.6 1C.
crude product was purified with flash column chromatography
of silica gel, eluted with CH2Cl2/petroleum ether (PE) to afford (d, J = 8.7 Hz, 2H), 8.66 (d, J = 8.7 Hz, 2H), 8.62 (d, J = 8.1 Hz,
the products. 2H), 7.77–7.66 (m, 4H), 3.56 (d, J = 7.2 Hz, 4H), 1.94 (br, 2H),
5: 1H NMR (300 MHz, CDCl3) d 9.13 (d, J = 8.1 Hz, 2H), 8.83
General Procedures for intramolecular Heck reactions. Dian- 1.38–1.22 (m, 64H), 0.87–0.82 (m, 12H). 13C NMR (75 MHz,
hydride 11 or 15 (1.0 equiv.), palladium diacetate (0.4 equiv.), CDCl3) d 169.7, 169.4, 132.3, 131.2, 130.9, 129.0, 128.8, 128.2,
tricyclohexylphosphine (0.7 equiv.) and potassium carbonate 127.4, 126.6, 125.8, 124.5, 122.2, 42.1, 37.2, 31.9, 31.5, 30.0,
(10 equiv.) in dry N,N-dimethylacetamide (DMAc) were stirred 29.9, 29.63, 29.58, 29.5, 29.3, 26.4, 22.7, 14.1. HR-ESI MS: calcd
at reflux overnight under a nitrogen atmosphere. After cooling for C70H95N2O4 (M + H+): 1027.7286; found: 1027.7284. Elem.
to room temperature, the mixture was diluted with CH2Cl2 and anal.: calcd for C70H94N2O4: C, 81.82%; H, 9.22%; N, 2.73%;
repeatedly washed with water. The organic solution was dried found: C, 81.75%; H, 9.35%; N, 2.70%.
over anhydrous Na2SO4 and the solvents were then removed
6: 1H NMR (300 MHz, CDCl3) d 9.34 (d, J = 9.0 Hz, 2H), 9.30
under reduced pressure. The crude product was purified with (m, 2H), 8.75 (m, 2H), 8.71 (d, J = 9.0 Hz, 2H), 7.85–7.80 (m, 4H),
column chromatography of silica gel, eluted with CH2Cl2/PE to 3.68 (d, J = 7.5 Hz, 4H), 1.99 (br, 2H), 1.46–1.13 (m, 64H),
afford the products.
0.88–0.82 (m, 12H). 13C NMR (100 MHz, CDCl3) d 169.69,
1
1: H NMR (400 MHz, CDCl3) d 9.12 (s, 2H), 9.09 (m, 2H), 169.67, 133.6, 133.0, 131.8, 129.8, 129.7, 128.9, 128.8, 128.0,
8.08 (m, 2H), 7.65 (m, 2H), 7.27 (m, 2H), 3.72 (d, J = 7.2 Hz, 4H), 126.3, 126.0, 123.6, 119.7, 42.6, 37.2, 31.9, 31.7, 30.1, 29.70,
1.99 (br, 2H), 1.41–1.22 (m, 64H), 0.86–0.83 (m, 12H); 13C NMR 29.65, 29.6, 29.4, 26.4, 22.7, 14.1. HR-ESI MS: calcd for
(100 MHz, CDCl3) d 169.7, 169.5, 133.7, 130.3, 129.5, 128.7,
C
70H95N2O4 (M + H+): 1027.7286; found: 1027.7274. Elem. anal.:
128.5, 127.4, 127.1, 126.2, 125.4, 125.1, 42.4, 37.3, 31.9, 31.6, calcd for C70H94N2O4: C, 81.82%; H, 9.22%; N, 2.73%; found: C,
30.05, 30.02, 29.68, 29.65, 29.60, 29.3, 26.4, 22.7, 14.1. HR-ESI 81.65%; H, 9.21%; N, 2.55%. m.p.: 106.5 1C.
MS: calcd for C66H93N2O4 (M + H+): 977.7130; found: 977.7103.
7: 1H NMR (400 MHz, CDCl3) d 9.94 (d, J = 4.0 Hz, 2H), 9.47
Elem. anal.: calcd for C66H92N2O4: C, 81.10%; H, 9.49%; N, (s, 2H), 7.87 (d, J = 8.0 Hz, 2H), 7.83 (d, J = 8.0 Hz, 2H), 7.76
2.87%; found: C, 81.02%; H, 9.51%; N, 2.91%. m.p.: 109.6 1C. (t, J = 12.0 Hz, 2H), 7.54–7.46 (m, 4H), 3.75 (d, J = 8.0 Hz, 4H),
2: 1H NMR (300 MHz, CDCl3) d 10.10 (s, 2H), 9.04 (d, J = 2.04 (br, 2H), 1.41–1.22 (m, 64H), 0.86–0.82 (m, 12H). 13C NMR
7.5 Hz, 2H), 8.76 (d, J = 7.5 Hz, 2H), 7.85–7.76 (m, 4H), 3.60 (100 MHz, CDCl3) d 169.3, 169.1, 135.4, 132.7, 130.7, 130.2,
(d, J = 7.5 Hz, 4H), 1.95 (br, 2H), 1.40–1.20 (m, 64H), 0.86–0.83 129.5, 129.0, 128.5, 127.7, 127.62, 127.59, 126.9, 126.8, 125.2,
(m, 12H). 13C NMR (75 MHz, CDCl3) d 169.0, 168.9, 132.0, 130.1, 42.9, 37.2, 31.9, 31.7, 30.1, 30.0, 29.7, 29.66, 29.60, 29.3, 26.5,
129.5, 128.5, 127.9, 125.9, 124.5, 123.6, 123.2, 119.4, 41.9, 37.4, 26.4, 22.7, 14.1. HR-ESI MS: calcd for C74H97N2O4 (M + H+):
31.92, 31.89, 31.5, 30.1, 29.72, 29.67, 29.4, 26.4, 22.7, 22.6, 14.1. 1077.7443; found: 1077.7445. Elem. anal.: calcd for C74H96N2O4:
HR-ESI MS: calcd for C66H93N2O4 (M + H+): 977.7130; found: C, 82.48%; H, 8.98%; N, 2.60%; found: 82.24%; H, 8.86%; N,
977.7152. Elem. anal.: calcd for C66H92N2O4: C, 81.10%; H, 2.54%. m.p.: 98 1C.
9.49%; N, 2.87%; found: C, 80.97%; H, 9.68%; N, 2.85%.
m.p.: 137.0 1C.
8: 1H NMR (400 MHz, CDCl3) d 10.51 (s, 2H), 9.45 (d, J =
8.0 Hz, 2H), 8.86 (d, J = 8.0 Hz, 2H), 8.16 (d, J = 12.0 Hz, 2H),
3: 1H NMR (400 MHz, CDCl3) d 9.28 (s, 1H), 9.26 (s, 1H), 9.18 8.00 (d, J = 8.0 Hz, 2H), 7.77–7.69 (m, 4H), 3.56 (d, J = 8.0 Hz,
(d, J = 8.0 Hz, 1H), 8.80 (d, J = 9.2 Hz, 1H), 8.76 (m, 1H), 8.37 4H), 1.97 (br, 2H), 1.39–1.18 (m, 64H), 0.84–0.79 (m, 12H).
(d, J = 8.0 Hz, 1H), 7.91–7.87 (m, 2H), 7.76 (t, J = 7.6 Hz, 1H), 13C NMR (100 MHz, CDCl3) d 169.0, 168.8, 133.14, 133.09,
7.56 (t, J = 7.6 Hz, 1H), 3.73 (d, J = 6.8 Hz, 2H), 3.56–3.42 (m, 131.3, 130.8, 129.9, 129.7, 128.8, 127.8, 127.7, 127.5, 126.4,
2H), 1.97 (br, 1H), 1.86 (br, 1H), 1.43–1.22 (m, 64H), 0.89–0.83 124.2, 123.8, 121.1, 120.7, 42.5, 37.1, 31.93, 31.91, 31.6, 30.2,
(m, 12H). 13C NMR (100 MHz, CDCl3) d 170.0, 169.63, 169.60, 29.74,29.72, 29.68, 29.0, 29.37, 26.4, 22.7, 14.1. HR-ESI MS:
168.1, 135.3, 134.9, 132.9, 130.7, 130.3, 130.2, 129.8, 129.4, calcd for C74H97N2O4 (M + H+): 1077.7443; found: 1077.7466.
128.7, 128.5, 127.9, 127.5, 126.22, 126.20, 126.1, 125.80, Elem. anal.: calcd for C74H96N2O4: C, 82.48%; H, 8.98%; N,
125.76, 125.5, 125.3, 124.1, 123.4, 120.0, 116.4, 42.3, 37.34, 2.60%; found: C, 82.41%; H, 8.99%; N, 2.52%. m.p.: 195.6 1C.
37.29 31.9, 31.6, 31.5, 30.1, 30.0, 29.63, 29.57, 29.3, 26.6, 26.4,
General procedures for thionation reactions. A solution of
22.7, 14.1. HR-ESI MS: calcd for C66H93N2O4 (M + H+): 977.7130; Lawesson’s reagent (5 equiv.) and diimide in dry toluene was
found: 977.7154. Calcd for C66H92N2O4: C, 81.10%; H, 9.49%; heated at reflux for 50 h. The resulting solution was cooled to
N, 2.87%; found: C, 81.05%; H, 9.62%; N, 2.90%. m.p.: 100.2 1C. room temperature and concentrated under reduced pressure. The
1
4: H NMR (300 MHz, CDCl3) d 10.33 (s, 1H), 9.38 (s, 1H), crude products were purified with silica gel column chromato-
8.98 (d, J = 3.9 Hz, 2H), 8.61 (d, J = 3.9 Hz, 2H), 7.75–7.72 (m, graphy (eluted with toluene/hexanes) to give the corresponding
4H), 3.62 (d, J = 4.5 Hz, 4H), 1.97 (br, 2H), 1.48–1.22 (m, 64H), product.
1
0.86–0.81 (m, 12H). 13C NMR (75 MHz, CDCl3) d 169.6, 169.2,
6-S: H NMR (400 MHz, CDCl3) d 10.13 (m, 2H), 9.21 (d, J =
132.4, 131.4, 129.4, 128.9, 128.1, 127.2, 126.8, 125.5, 124.1, 8.0 Hz), 8.80 (m, 2H), 8.71 (d, J = 8.0 Hz, 2H), 7.85–7.79 (m, 4H),
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NJC
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4.05 (d, J = 8.0 Hz, 4H), 2.17 (br, 2H), 1.37–1.22 (m, 64H), 0.87–
0.82 (m, 12H). 13C NMR (120 MHz, CDCl3) d 197.9, 171.1, 134.0,
133.5, 132.1, 130.8, 130.1, 129.3, 129.0, 128.0, 127.0, 123.8,
122.9, 119.3, 100.0, 45.5, 36.5, 31.9, 31.8, 30.1, 29.7, 29.6,
29.6, 29.3, 26.4, 22.7, 14.1. Calcd for C70H95N2O2S2 (M + H+):
1059.6830; found: 1059.6839. m.p.: 75.0 1C.
7-S: 1H NMR (400 MHz, CDCl3) d 9.97 (d, J = 2.8 Hz, 2H), 9.68
(d, J = 8.0 Hz, 2H), 7.78–7.67 (m, 6H), 7.34–7.24 (m, 4H), 4.03
(t, J = 8.0 Hz, 4H), 2.18–2.14 (m, 2H), 1.39–1.20 (m, 64H), 0.86–
0.81 (m, 12H). 13C NMR (100 MHz, CDCl3) d 196.6, 170.4, 134.9,
132.8, 131.5, 130.4, 129.1, 129.1, 128.5, 128.3, 127.7, 127.7,
127.6, 126.6, 126.4, 125.2, 125.0, 45.7, 36.6, 31.95, 31.93, 31.7,
30.2, 30.1, 29.74, 29.73, 29.70, 29.68, 29.66, 29.40, 29.39, 26.4,
22.7, 14.2. Calcd for C74H97N2O2S2 (M + H+): 1109.6986; found:
1109.6952. Elem. anal.: calcd for C74H96N2O2S2: C, 80.09%;
H, 8.72%; N, 2.52%; found: C, 79.94%; H, 8.87%; N, 2.41%.
m.p.: 65.7 1C.
1
8-S: H NMR (400 MHz, CDCl3) d 10.39 (s, 2H), 8.93 (d, J =
8.0 Hz, 2H), 7.93 (d, J = 8.0 Hz, 2H), 7.95–7.67 (m, 4H), 7.60–7.54
(m, 4H), 3.54 (d, J = 8.0 Hz, 4H), 1.96 (br, 2H), 1.37–1.20 (m,
64H), 0.85–0.82 (m, 12H). 13C NMR (100 MHz, CDCl3) d 196.1,
170.3, 133.3, 133.0, 131.9, 131.2, 129.7, 129.3, 128.6, 127.7,
127.4, 125.9, 125.0, 124.1, 123.0, 122.9, 121.1, 45.1, 36.5, 32.0,
31.9, 31.7, 30.2, 29.78, 29.76, 29.7, 29.43, 29.40, 26.4, 22.72,
22.70, 14.1. Calcd for C74H97N2O2S2 (M + H+): 1109.6986; found:
1109.6949. Elem. anal.: calcd for C74H96N2O2S2: C, 80.09%;
H, 8.72%; N, 2.52%; found: C, 80.12%; H, 8.87%; N, 2.51%.
m.p.: 137.0 1C.
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We acknowledge financial support from the National Natural
Science Foundation of China (Projects 21174004, 21222403 and
51473003).
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