Metal-free Annulation at the Ortho- and Bay-Positions of Perylene Bisimide Leading to Lateral π-Extension with Strong NIR Absorption

Article abstract of DOI:10.1021/acs.joc.8b01303

A novel ortho/bay annulation reaction of perylene bisimide (PBI) has been explored in a single step synthetic procedure using perylene bisimide 1 and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) in the absence of any metal catalyst. The single crystal solid-s

Full text of DOI:10.1021/acs.joc.8b01303

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Note
Metal-free Annulation at Ortho- and Bay- Positions of Perylene
Bisimide Leading to Lateral -Extension with Strong NIR Absorption
Ramprasad Regar, Ruchika Mishra, Pradip Kumar Mondal, and Jeyaraman Sankar
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.8b01303 • Publication Date (Web): 23 Jul 2018
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The Journal of Organic Chemistry
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Metalꢀfree Annulation at Orthoꢀ and Bayꢀ Positions of Perylene Bisimide
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Leading to Lateral ꢀꢀExtension with Strong NIR Absorption
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Ramprasad Regar, Ruchika Mishra, Pradip Kumar Mondal and Jeyaraman Sankar*
Department of Chemistry, Indian Institute of Science Education and Research, Bhopal 462 066, India
Supporting Information Placeholder
ABSTRACT: A novel ortho/bay annulation reaction of perylene bisimide(PBI) has been explored in a single step synthetic procedure using
perylene bisimide 1 and 1,8ꢀDiazabicyclo[5.4.0]undecꢀ7ꢀene (DBU) in the absence of any metal catalyst. The single crystal solid state Xꢀray
diffraction structure showed a distorted framework of DBUꢀfused PBI 2. Compound 2 exhibited intense nearꢀinfrared absorption up to 950
nm. Reversible protonation and deprotonation accompany drastic changes in photophysical characteristics. Further, the reaction of perylene
biscarboxyanhydride with DBU offered caprolactam ringꢀsubstituted perylene bisimide 3.
Over the past few years, extensive efforts have been channeled into
the development of ꢀꢀconjugated molecules for various futuristic
applications such as organic solar cells, organic fieldꢀeffect transisꢀ
tors, artificial photoꢀsystems etc.1 Among the plethora of polyaroꢀ
matic molecules available, peryleneꢀ3,4,9,10ꢀtetracarboxyl bisiꢀ
mides (PBIs) have emerged as the fascinating class of aromatic
molecules due to their tunable absorption and emission features
with very high thermal and photoꢀchemical stability.2 PBI derivaꢀ
tives find widespread applications in organic photovoltaics,3 organꢀ
ic fieldꢀeffect transistors,4 sensors,5 bioꢀimaging6 and supramolecuꢀ
lar assemblies7 owing to their tunable ꢀꢀbackbone, which is further
achieved either by aromatic core extension or expansion. Bayꢀ
functionalization8 is an practical aproach to extend ꢀꢀframework of
PBI, henceforth creating new PBI derivatives with outstanding
optoelectronic properties. Core expansion of perylene ꢀꢀsystem in
longitudinal (NꢀN axis) manner has provided nearꢀinfrared absorbꢀ
ing dyes such as terrylene bisimides up to hexarylene bisimides.9
Core expansion along the short molecularꢀaxis of perylene bisimide
is another plausible way to influence the aromatic ꢀꢀcloud of PBIs.
The most prevalent methods used to achieve this involve baseꢀ
mediated cyclization, metal catalyzed cyclization, lightꢀpromoted
and DielsꢀAlder cycloaddition.10 Core expanded PBIs often have
ionic PBI radical was reported using Nꢀheterocyclic carbene.12j
Fusion at bay/ortho positions have been shown to form ladder type
oligomers by copperꢀmediated coupling reactions.13aꢀc Very recentꢀ
ly, a copperꢀcatalyzed ortho/bay direct diamination of PBIs have
also been reported.13d However, metalꢀfree access to simple orꢀ
tho/bay annulated systems remain rare. As a result of this, simultaꢀ
neous fusion at ortho and bay positions of PBI is challenging and
rewarding.
Scheme 1. Synthetic scheme for DBUꢀannulated perylene bisimide
2 and 4.
R
N
R
N
O
O
O
O
N
N
N
6
Toluene
1
14
16
35
12
N
13
17
7
140 °C, 24 h
10 eqv.
alkyl =
O
N
R
O
O
N
R
O
aryl =
R =
, 2
alkyl
R =
, 1
alkyl
, 4
aryl
, Ar-PBI
aryl
In the current work, we report an interesting annulation
reaction of DBU at bayꢀ and orthoꢀ positions of PBI for the conꢀ
struction of a heteroatom containing 5ꢀmembered cyclic unit in a
single step synthetic procedure. In this cyclization, the reaction was
catalyzed by DBU itself rather than by any metal catalyst. The
synthesized compound 2 was nonꢀfluorescent and showed intense
absorption across the visible to nearꢀinfrared region. The utility of
this reaction has been explored to provide a caprolactam tail imide
substituted compound 3. The lateral coreꢀexpanded perylene bisiꢀ
mide 2, formally a DBU appended PBI at bayꢀ and orthoꢀpositions,
benzene rings or heterocyclic rings annulated in the perylene bay
ꢀ
region. The resultant chromophores are coronene diimide (CDI),
dibenzocoronene diimide, and dinaphthocoronene diimide, which
inherit properties from both coronenes and PBIs.11 Expanding the
aromatic core in the bayꢀarea is comparatively easy and is much
exploited. However, functionalization at the ortho position is relaꢀ
tively difficult as it requires expensive catalysts and longer reaction
times with poor yields.12aꢀi Meanwhile, an orthoꢀsubstituted zwitterꢀ
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was synthesized through an uncatalyzed, single step reaction of PBI
20.96°, respectively. On the unsubstituted PBI bay side the
C6C16C17C7 dihedral angle is 6.36° as shown in scheme 1.
1
2
3
4
1 with DBU. In this reaction, DBU acted as a reactant as well as a
base and led to the formation of a higher polar brown compound 2.
After repetitive column chromatography using dichloroꢀ
methane/ethyl acetate solvent mixture, the brown fraction was
isolated in 32% yield.
Scheme 2. Proposed mechanism for the formation of 2 & 4.
N
N
N
N
H
5
6
7
8
N
N
O
N
O
O
N
O
O
N
O
1H NMR in CDCl3 at room temperature (Figure S9)
indicated three clearly resolved signals from the aromatic PBI core
and four wellꢀresolved signals for imideꢀsubstituted isopentyl group
with a few unresolved signals in the aliphatic region. The absence of
resonances for two protons of the aromatic region of PBI hinted at
a probable annulation. HRMSꢀAPCI spectra (Figure S17) revealed
the molecular ion peak to be a combination of PBI and DBU lackꢀ
ing four protons. Considering this, the brown product was thought
to be a DBUꢀsubstituted compound 2, but the room temperature
NMR spectra did not support the assignment. A CuIꢀcatalyzed
annulation of fiveꢀmembered heterocyclic ring on naphthalene
diimide (NDI) core had been reported earlier.14 Recently, we have
O
N
O
R
R
R
R
O2
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N
N
N
N
N
N
H
O
N
O
O
N
O
O
N
O
O
N
O
R
R
R
R
O2
R =
N
N
O
N
O
O
N
O
also reported an ortho/bayꢀring annulated 5ꢀmembered pyrroloꢀ
R
R
perylene bisimide from alkynyl derivative of PBI with DBU.15 Takꢀ
ing a cue from this, the brown compound was assumed to be a
DBU fused at one bay and one orthoꢀposition of PBI. The broadenꢀ
ing of proton NMR resonances was presumed to be due to the
fluxional behavior of the DBU unit. This is due to the flipping of
DBU ring that can be arrested at lowꢀtemperature. To probe the
same, a variable temperature 1H NMR experiment (Figure S9) was
conducted in CDCl3. The emergence of new signals between 1.5
and 5.1 ppm was observed, and these signals were assigned to DBU
ring protons. No new signals were observed in aromatic region. It
was found that at lowꢀtemperatures compound 2 shows clearly
resolved signals as compared to room temperature spectra. So all
the facts discussed above, along with 13CꢀNMR spectrum conꢀ
firmed the fusion of DBU at PBI b/oꢀposition to form compound 2
(as shown in scheme 1). Compound 2 has good solubility in comꢀ
mon organic solvents, such as dichloromethane, chloroform, toluꢀ
ene, and tetrahydrofuran at room temperature. The presence of
conjugated aromatic rings along with the presence of the electronꢀ
rich amino group would be responsible for the color and strong
absorption in the visible region. The melting points of newly synꢀ
thesized molecules were determined by differential scanning caloꢀ
rimetry technique. Compounds 2 and 3 start melting at 333 and
404 °C, respectively. Further, the present reaction procedure proꢀ
vided DBU fused PBI derivative 4 as shown in scheme 1 with an Nꢀ
aryl PBI derivative. When compound 1 was reacted with 1,5ꢀ
diazabicyclo[4.3.0]nonꢀ5ꢀene (DBN), the reaction did not proceed
as expected and resulted in a complicated mixture. The formation
of compound 2 probably proceeds by the attack of alkene carbon of
DBU at the orthoꢀposition of PBI to form a CꢀC bond followed by
oxidation (Scheme 2). Further, an oxidation offers compound 2 by
achieving the aromatization.
The synthesized molecule 2 showed a broad and intense
absorption ranging from visible to nearꢀinfrared region. The abꢀ
sorption spectrum recorded in toluene displayed a λmax at 820 nm
(ε = 24000 Mꢀ1 cmꢀ1) and a comparatively lessꢀresolved vibronic
absorption feature between 400 and 600 nm (Figure 2, left). The
broad and intense band between 580 and 950 nm is a mixture of πꢀ
π* transition for the core extension and chargeꢀtransfer (CT) tranꢀ
sition, involving the Nꢀheterocyclic aromatic ring and electronꢀrich
dialkylamino group.
Figure 1. Single crystal Xꢀray diffraction structure of compound 2 (Alkyl groups
on the imide nitrogens have been removed for clarity).
Compound 2 was found to be nonꢀfluorescent as comꢀ
pared to parent PBI 1 owing to strong nonꢀradiative decay, stemꢀ
ming from the structural floppiness of the DBU ring along limited
with contribution from a charge transfer (Figure S5). To underꢀ
stand the CT nature, absorption spectra for compound 2 were recꢀ
orded in toluene, THF, MeOH, DMF and DMSO as shown in
figure 2 (right). A bathochromic shift of around 70 nm was obꢀ
served at the CT band as the polarity of the solvent increased,
whereas the splitting of bands in the visible region observed was not
typical of unsubstituted PDI 1. This indicates that the CT state is
getting stabilized with increasing solvent polarity.
It was crucial to obtain a solid state structural proof for
the formation of compound 2. To achieve this, suitable crystals for
single crystal Xꢀray diffraction analysis (CCDC No. 1817886) were
obtained through vapor diffusion of methanol into a dichloroꢀ
methane solution of compound 2. The solid state structure reꢀ
vealed a distorted framework for compound 2, where DBU has
been fused at b/oꢀpositions of PBI as shown in figure 1. The two
naphthalene units of perylene core deviated from coꢀplanarity due
to annulation, probably driven by steric repulsion. The
C12C13C14C1 and C13C14C1C35 dihedral angles are 19.72° and
It is essential to explore the utility of this reaction further.
While it is interesting to investigate the reactivity of DBU with PBI,
it would be rewarding to understand DBU’s reactivity towards the
parent insoluble peryleneꢀ3,4,9,10ꢀtetracarboxylic dianhydride
(PDA). To probe the same, PDA has been subjected to identical
reaction conditions (Scheme 4). Surprisingly, DBU underwent
nucleophilic reaction17 to give an unprecedented PBI derivative
again. The DBU ring was opened and a caprolactam ring substitutꢀ
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ed perylene bisimide 3 was obtained, instead of a ring an annulated
product similar to that of compound 2.
Sc
h
e
me
3
. Protonation and deprotonation of compound 2.
Page 3 of 6
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The successive addition of aliquots of TFA forced the
Figure 2. Absorption profiles of compound 2 in toluene (µM) (left) and solvent
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dependence (right).
CT band to disappear. Simultaneously, a few peaks emerged at 515,
480 and 450 nm in the absorption spectrum. The fluorescence
intensity of bands at 532 and 569 nm increased gradually with the
increasing addition of TFA aliquots as shown in figure 4. The proꢀ
tonation resulted in the sharp vibronic feature in the absorption
spectra resembling unsubstituted PBI with absorption maxima at
515 nm. The emission spectrum was also similar to parent PBI with
emission maxima at 532 nm. This further confirms that the intraꢀ
molecular charge transfer interactions are suppressed as the elecꢀ
tronꢀrich carbon is getting protonated and the resultant +ve charge
being stabilized by the nitrogen atoms in the DBU ring as shown in
the scheme 3.
To gain further insight into the frontier molecular orbitꢀ
als of compound 2, DFT calculations were performed at the
B3LYP/6ꢀ31g* level using Gaussian 09 suite of programs.16 These
calculations provided insight into the electron delocalization in
frontier molecular orbitals. The electron density in HOMO was
delocalized over the whole molecule whereas the electron density
in LUMO was predominantly spread only over PBI core with conꢀ
tribution from the extended 5ꢀmembered heterocyclic ring as
shown in figure 3 (A). Hence, the broad band between 580 and 950
nm can be assigned to extension of conjugation and CT transition
which originates from HOMO to LUMO transition.
Figure 4. Absorption profile (left), and fluorescence profile excited at 480 nm
(right) of compound 2 (8 µM) in the presence of different concentrations of
TFA in CH3CN solution.
Figure 3. Frontier molecular orbitals (A) and cyclic voltammogram (B) of
compound 2 and 1 recorded in dichloromethane at a scan rate of 0.1 V/s with
respect to SCE.
Consequently, the quenched fluorescence was regained
after protonation, due to the arrest of intramolecular CT interacꢀ
tions. Therefore, very weakly fluorescent 2 becomes highly fluoresꢀ
cent in the presence of acid. This was further supported by the
frontier molecular orbitals of [2+H+]. The electron density of
HOMO and LUMO are delocalized over the whole PBI core with
negligible contribution from extended heterocyclic moiety in
[2+H+] (Figure S20) which are of typical PBIꢀlike HOMO and
LUMO. The fluorescence turn off can be achieved by deprotonaꢀ
tion by the addition of a base such as triethylamine (TEA). The
addition of an aliquot of TEA in CH3CN to the solution of [2+H+]
in CH3CN resulted in the reappearance of CT band between 580
and 950 nm (Figure S2). The fluorescence intensity decreased
rapidly at 532 and 569 nm after gradual addition of TEA solution
(Figure S3). The switching of fluorescence can be mannered by the
alternate additions of TFA and TEA (Figure S4). The reversibility
of this switching was performed for several cycles suggesting the
In order to understand the redox characteristics of comꢀ
pound 2, cyclic voltammetric studies were conducted. The experiꢀ
ment was performed under argon in dichloromethane with 0.1 M
tetrabutylammonium hexafluorophosphate as supporting electroꢀ
lyte, with a scan rate of 100 mV/s. Compound 2 exhibited two
reversible reductions at ꢀ0.88 and ꢀ1.03 V whereas PBI 1 showed
two reductions at ꢀ0.69 and ꢀ0.87 V versus SCE. Also, one reversiꢀ
ble and one irreversible oxidations each were obtained at 0.43 and
1.23 V, respectively for compound 2 as shown in figure 3 (B). The
reversible reductions are expected from electronꢀdeficient PBI core
while the oxidations clearly reflect the electronꢀrich nature of annuꢀ
lated dialkylamino ring. It shows that the compound 2 is both more
easy to oxidize and less susceptible to reduce as compared to typical
PBI 1.
To exploit the CT characteristics, a protonation study
was conducted. Protonation of the electronꢀrich carbon atom
(C35) should, in turn, affect the CT band by restricting the extendꢀ
ed πꢀconjugation (scheme 3) and therefore should be revealed by
absorption and emission spectrum. To verify this, compound 2 in
acetonitrile (CH3CN) was titrated against an acetonitrile solution
of trifluoroacetic acid (TFA).
1
chemical robustness of compound 2. The H NMR showed resoꢀ
nances for all protons upon adding TFA to compound 2 in CDCl3
at room temperature. The signals which were absent at room temꢀ
perature were regained upon TFA addition (Figure S10). Also, the
appearance of new signal at 5.75 ppm for one proton confirms the
protonation at the carbon atom (C35 as shown in scheme 3) in the
dialkylamino group. This observation further assures the arrest of
fluxionality of DBU unit on protonation.
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Scheme 4. Synthetic scheme for imide substitution of DBU and
Page 4 of 6
high resolution mass spectrometer from Bruker Daltonics coupled
to a Waters Acquity UPLC system. Steady state absorption measꢀ
urements were done on Cary 5000 UV/VIS/NIR spectrophotomeꢀ
ter. Steadyꢀstate fluorescence emission measurements were done
on a Horiba Jobin Yvon fluorolog 3ꢀ111. Quartz cell with optical
path length of 10 mm was used for all measurements. Cyclic voltꢀ
ammetric measurements were carried out using CH potentiostat
from CHI Instruments. CV experiments were done under continuꢀ
ous argon flow and a conventional threeꢀelectrode electrochemical
cell was used. A glassy carbon working, a platinum wire counter and
SCE reference electrodes were used. All the measurements were
done in dichloromethane solution with 0.1 M tetrabutylammoniꢀ
um hexafluorophosphate (TBAPF) as supporting electrolyte. All
the voltammograms were recorded at a scan rate of 100 mV/s.
Single crystal Xꢀray diffraction measurements were carried out on a
Bruker Apex diffractometer with a CCD detector with MoꢀKα radiꢀ
ation. All IR spectra were obtained using Perkin Elmer FTIR sysꢀ
tem as neat films and selected peaks are reported in cmꢀ1. DFT calꢀ
culations were performed using Gaussian 09 software suite.
Compound 1:18 A mixture of pentꢀ3ꢀylamine (652 ꢁL, 5.612
mmol), peryleneꢀ3,4:9,10ꢀtetracarboxylic dianhydride (1000 mg,
2.551 mmol) and imidazole (5204 mg, 76.53 mmol) was stirred at
140 °C for 4 hrs and diluted with ethanol. This was followed by the
addition of 2M HCl (100 mL). The reaction mixture was then
allowed to settle down. The precipitate thus formed was collected
through vacuum filtration and dried in oven. Further purification
by silica gel chromatography using chloroform/hexane as eluents
provided the desired compound 1 in 80% (1082 mg) yield. 1H
1
2
3
4
5
6
7
8
single crystal Xꢀray diffraction structure for compound 3.
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Compound 3 has been characterized by NMR (Figure
S11&S12), and mass (Figure S18) spectrometric analyses. The
absorption and fluorescence spectrum of compound 3 resembled
that of simple PBI 1 (Figure S6) as functionalization on PBI nitroꢀ
gens seldom perturbs the frontier orbitals, owing to the presence of
a nodal plane along the imide nitrogens (Figure S21). The forꢀ
mation of compound 3 was unambiguously confirmed by single
crystal Xꢀray diffraction structure (CCDC No. 1824653) as shown
in Scheme 4. Compound 3 shows a planar conformation.
Scheme 5. Proposed mechanism for the formation of 3.
N
N
N
N
N
N
O
N
N
O
O
O
O
O
O
O
O
O
O
O
NMR (500 MHz, CDCl3) δ (ppm) 8.66 (d,
(d, = 8.0 Hz, 4H), 5.07 (m, 2H), 2.31 – 2.22 (m, 4H), 1.99 – 1.91
(m, 4H), 0.93 (t,
= 7.5 Hz, 12H). HRMS (APCI) m/z: [M+H]+
J = 7.9 Hz, 4H), 8.59
J
The formation of compound 3 can be explained as a nucleophilic
attack by nitrogen atom of 6ꢀmembered ring of DBU at the carbonꢀ
yl carbon of anhydride group followed by ring opening(Scheme 5).
J
calcd for C34H31N2O4 531.2278; found 531.2247.
Compound 2: In a dry sealed tube, a mixture of 1 (200 mg, 0.3773
mmol) and 1,8ꢀdiazabicyclo[5.4.0]ꢀundecꢀ7ꢀene (DBU) (562 ꢁL,
3.773 mmol) in dry toluene (10 mL) was stirred at 140 °C for 24
hrs. Reaction progress was monitored using TLC. After 24 hrs, the
reaction mixture was subjected to a water work up and washed with
dichloromethane twice. Organic layer was collected over anhyꢀ
drous sodium sulphate and dried under reduced pressure. Crude
mixture was subjected to column chromatography for further puriꢀ
fication. The brown compound was purified using alumina column
chromatography with dichloromethane/ethyl acetate solvent mixꢀ
ture in 32% (82 mg) yield with remaining unreacted starting mateꢀ
In summary, a new DBU annulation reaction on PBI,
without the use of any catalyst has been explored in a single synꢀ
thetic operation. The solid state structure of the molecule 2 reꢀ
vealed a distorted PBI core. The annulation resulted in interesting
CT properties of compound 2. The protonation can manipulate the
intramolecular charge transfer interactions. As a result, compound
2, which is weakly fluorescent, becomes highly fluorescent upon
protonation. Hence, compound 2 acts as a pHꢀsensitive fluoroꢀ
phore with good reversibility and robustness. The utility of this
reaction has further been explored to give caprolactamꢀring substiꢀ
tuted perylene bisimide 3 from PDA. Further, the panchromatic
absorption feature makes molecule 2 a promising candidate for
organic photovoltaic (OPV) applications. Further studies in this
direction are underway in our laboratory.
1
rial and insoluble fraction. H NMR (500 MHz, CDCl3, 253K) δ
(ppm) 8.60 – 8.45 (merged doublets, 5H), 7.58 (d,
1H), 5.18 – 4.86 (m, 2H), 4.52 (broad t, 1H), 3.93 (t,
J
J
= 6.9 Hz,
= 12.5 Hz,
1H), 3.76 (d, J = 11.0 Hz, 1H), 3.52 (d, J = 21.8 Hz, 2H), 3.42 (d, J
= 13.1 Hz, 1H), 2.82 (broad t, 1H), 2.26 (broad m, 5H), 2.07
(broad s, 1H), 1.87 (broad m, 8H), 1.61 (broad s, 1H), 0.87 (m,
12H). 13C NMR (126 MHz, CDCl3, 298K) δ (ppm) 164.7, 164.7,
163.9, 163.4, 163.3, 153.8, 135.1, 133.1, 130.2, 129.6, 129.4, 128.8,
128.4, 126.1, 125.6, 124.7, 123.9, 122.1, 120.0, 119.8, 119.5, 93.5,
56.2, 55.9, 52.6, 51.4, 45.9, 45.7, 26.4, 25.9, 24.0, 23.8, 23.4, 22.4,
10.6, 10.3. HRMS (APCI) m/z: [M+H]+ calcd for C43H43N4O4
679.3279; found 679.3252. IR stretching frequencies (cmꢀ1) 2961,
2926, 2869, 1683, 1644, 1584, 1542, 1338, 1069, 802. The ORTEP
diagram and structure refinement data of compound 2 were proꢀ
vided in supporting information (Figure S22 & Table S1).
EXPERIMENTAL SECTION
General Experimental methods: All reactions were carried out unꢀ
der argon atmosphere. Spectroscopic grade solvents were used for
measuring electrochemical and optical properties. Unless otherwise
noted, the chemicals received from Sigma Aldrich and Alfa Aesar
were used without further purification. Samples synthesized were
purified by silica gel (100ꢀ200 mesh) and neutral alumina column
chromatography followed by recrystallisation. 1H NMR and 13C
NMR spectra were recorded on Bruker Avance 500 MHz or 700
MHz spectrometers in CDCl3 with TMS as internal reference. The
chemical shift values have been referenced to the residual solvent
signals. HRMS measurements were recorded on a microTOFꢀQII
Compound 3: In a dry sealed tube, PDA (200 mg, 0.5012 mmol) in
toluene (10 mL) was degassed with argon for 15 minutes. Then
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The Journal of Organic Chemistry
research fellowship. We sincerely thank Dr. R. V. Ramana Reddy for
DBU (760 ꢁL, 5.102 mmol) was added and stirred at 140 °C for 24
hrs. After which the reaction mixture was subjected to a water
workup and washed with chloroform twice. Organic layer was colꢀ
lected over anhydrous sodium sulphate and concentrated under
reduced pressure. Crude mixture was subjected to silicaꢀgel column
chromatography for purification. After repetitive columns, pure
compound was obtained in chloroform/ethylacetate solvent mixꢀ
1
2
3
4
5
6
7
8
help in DFT calculations. We acknowledge CRESTꢀMHRDꢀFAST,
IISER Bhopal for funding, and IISER Bhopal for facilities and infraꢀ
structure.
REFERENCES
(1) (a) Facchetti, A. Semiconductors for organic transistors Mater. Toꢀ
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1
ture in 20% (71 mg) yield. H NMR (500 MHz, CDCl3, 298K) δ
(ppm) 8.47 (d,
J
= 7.9 Hz, 4H), 8.34 (d,
J = 8.0 Hz, 4H), 4.19 –
4.12 (m, 4H), 3.52 (t,
J
= 7.1 Hz, 4H), 3.38 (m, 4H), 2.53 – 2.47
9
(m, 4H), 1.99 – 1.89 (m, 4H), 1.69ꢀ1.64 (m, 12H). 13C NMR (176
MHz, CDCl3, 298K) δ (ppm) 175.9, 163.4, 134.7, 131.5, 129.4,
126.4, 123.2, 123.1, 49.5, 45.9, 38.5, 37.4, 30.1, 28.7, 26.8, 23.5.
HRMS (APCI) m/z: [M+H]+ calcd for C42H41N4O6 697.3021;
found 697.3032. IR stretching frequencies (cmꢀ1) 2927, 2855, 1690,
1651, 1592, 1440, 1356, 808. The ORTEP diagram and structure
refinement data of compound 3 were provided in supporting inꢀ
formation (Figure S23 & Table S1).
ganic semiconductors in organic electronics Adv. Mater. 2010, 22
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Compound ArꢀPBI:18 Synthetic procedure is same as that of comꢀ
pound 1 using 2,6ꢀdiisopropylaniline. Yield 72% (1306 mg). 1H
(2) (a) Würthner, F. Perylene bisimide dyes as versatile building blocks
for functional supramolecular architectures Chem. Commun. 2004,
1564. (b) Wasielewski, M. R. Energy, charge, and spin transport in
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ics: yesterday, today, and tomorrow Adv. Mater. 2012, 24, 613. (b)
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ic solar cells Dyes and Pigments 2013, 98, 160. (c) Wu, Y.; Zhang, Q.;
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NMR (500 MHz, CDCl3, 298K) δ (ppm) 8.73 (d,
J
= 7.9 Hz, 4H),
= 7.8
8.68 (d, = 7.9 Hz, 4H), 7.44 (t, = 7.8 Hz, 2H), 7.29 (d, J
J
J
Hz, 4H), 2.69 (m, 4H), 1.12 (mixed singlets, 24H). 13C NMR (126
MHz, CDCl3, 298K) δ (ppm) 163.5, 145.6, 135.1, 132.1, 130.5,
130.2, 129.7, 126.8, 124.1, 123.4, 123.3, 29.2, 24.0. HRMS (APCI)
m/z: [M+H]+ calcd for C48H42N2O4 711.3217; found 711.3191.
Compound 4: Synthetic procedure is same as that of compound 2
using ArꢀPBI. Yield 26% (63 mg). 1H NMR (500 MHz, CDCl3,
253K) δ (ppm) 8.71ꢀ8.65 (merged doublets, 2H), 8.61 – 8.50 (m,
diimides J. Mater. Chem. A 2016, 4, 17604.
(4) Zhan, X.; Facchetti, A.; Barlow, S.; Marks, T. J.; Ratner, M. A.;
Wasielewski, M. R.; Marder, S. R. Rylene and related diimides for orꢀ
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planar πꢀconjugated molecules: adaptable building blocks for organic
nanodevices Acc. Chem. Res. 2008, 41, 1596. (b) Kaloo, M. A.; Mishꢀ
ra, R.; Sankar, J. Perylenebisimideꢀbased multiꢀmodal cyanide recogꢀ
nition: molecular logic gate deciphering magnetic memory units J.
3H), 7.63 (d,
7.28 (m, 4H), 4.57 – 4.44 (m, 1H), 3.95 (t,
(d, = 11.0 Hz, 1H), 3.55 – 3.46 (m, 2H), 3.45 – 3.38 (m, 1H),
J
= 8.0 Hz, 1H), 7.47 (merged triplets, 2H), 7.38 –
J
= 12.6 Hz, 1H), 3.84
J
3.05 – 2.82 (m, 2H), 2.80 – 2.67 (m, 2H), 2.66 – 2.54 (m, 1H),
2.21 – 2.04 (m, 2H), 1.88 (m, 4H), 1.61 (broad s, 1H), 1.14 (broad
m, 24H). 13C NMR (126 MHz, CDCl3, 298K) δ (ppm) 164.7,
164.1, 164.1, 163.6, 155.2, 145.7, 142.4, 136.7, 136.5, 134.4, 132.5,
131.3, 131.3, 131.1, 130.7, 130.1, 129.6, 129.4, 127.7, 126.9, 126.9,
125.8, 124.1, 123.9, 123.9, 121.8, 121.1, 121.0, 120.8, 119.5, 118.5,
102.9, 94.8, 52.7, 47.3, 46.9, 29.7, 29.2, 29.1, 27.6, 27.3, 24.6, 24.1,
24.1, 24.0, 23.9, 23.3. HRMS (APCI) m/z: [M+H]+ calcd for
C57H55N4O4 859.4218; found 859.4248.
Mater. Chem. C 2015, 3, 1640.
(6) (a) Peneva, K.; Mihov, G.; Nolde, F.; Rocha, S.; Hotta, J. –I.;
Braeckmans, K.; Hofkens, J.; UjiꢀI, H.; Herrmann, A.; Müllen, K. Waꢀ
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ASSOCIATED CONTENT
Supporting Information
(7) Würthner, F.; SahaꢀMöller, C. R.; Fimmel, B.; Ogi, S.; Leowanawat,
P.; Schmidt, D. Perylene bisimide dye assemblies as archetype funcꢀ
tional supramolecular materials Chem. Rev. 2016, 116, 962.
(8) (a) Huang, C.; Barlow, S.; Marder, S. R. Peryleneꢀ3,4,9,10ꢀ
tetracarboxylic acid diimides: synthesis, physical properties, and use
in organic electronics J. Org. Chem. 2011, 76, 2386. (b) Mishra, R.;
Lim, J. M.; Son, M.; Panini, P.; Kim, D.; Sankar, J. Tuning the elecꢀ
tronic nature of mono‐bay alkynyl–phenyl‐substituted perylene bisiꢀ
mides: synthesis, structure, and photophysical properties Chem. Eur.
Synthetic scheme of precursor, NMR, mass, IR, Frontier MOs, crystalꢀ
lographic data, absorption and fluorescence switching spectra have
been provided. The Supporting Information is available free of charge
on the ACS Publications website.
AUTHOR INFORMATION
J
. 2014, 20, 5576. (c) Shoaee, S.; Eng, M. P.; An, Z.; Zhang, X.; Barꢀ
Corresponding Author
low, S.; Marder, S. R.; Durrant, J. R. Inter versus intraꢀmolecular phoꢀ
toinduced charge separation in solid films of donor–acceptor moleꢀ
cules Chem. Commun. 2008, 4915.
*Eꢀmail: sankar@iiserb.ac.in
ACKNOWLEDGMENT
(9) Avlasevich, Y.; Li, C.; Mullen, K. Synthesis and applications of coreꢀ
enlarged perylene dyes J. Mater. Chem. 2010, 20, 3814.
(10) (a) Usta, H.; Newman, C.; Chen, Z.; Facchetti, A. Dithienocoroꢀ
nenediimideꢀbased copolymers as novel ambipolar semiconductors
The authors thankfully acknowledge Prof. Alakesh Bisai, IISER Bhopal
and a reviewer for their insightful suggestions on the mechanism of
formation of the compounds. RR thanks DSTꢀINSPIRE for a senior
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