Syntheses and properties of 1,6 and 1,7 perylene diimides and tetracarboxylic dianhydrides

Article abstract of DOI:10.1021/ol2019407

Via Sonogashira cross-coupling with different alkynes, 1,6 and 1,7 perylene diimides (PDIs) and perylene tetracarboxylic dianhydrides (PTCDs) were synthesized from the corresponding regioisomeric mixture of 1,6/1,7-dibromo precursors. Both bulky triphenyl

Full text of DOI:10.1021/ol2019407

ORGANIC
LETTERS
2011
Vol. 13, No. 17
4724–4727
Syntheses and Properties of 1,6 and
1,7 Perylene Diimides and Tetracarboxylic
Dianhydrides
Nisha V. Handa, Kayla D. Mendoza, and Laura D. Shirtcliff*
Department of Chemistry, Oklahoma State University, 107 Physical Sciences,
Stillwater, Oklahoma 74074, United States
laura.shirtcliff@okstate.edu
Received July 18, 2011
ABSTRACT
Via Sonogashira cross-coupling with different alkynes, 1,6 and 1,7 perylene diimides (PDIs) and perylene tetracarboxylic dianhydrides (PTCDs)
were synthesized from the corresponding regioisomeric mixture of 1,6/1,7-dibromo precursors. Both bulky triphenyl propyne (TPP) groups and
nonbulky hexyl groups allow for facile chromatographic separation. The optical properties of these compounds are discussed. Neutral bay
substituents hypsochromically shift both the absorption and emission through deformation from planarity of the perylene core.
Perylene tetracarboxylic diimides (PDIs) have re-
ceived considerable attention in both academic and
industrial research due to the favorable combination of
large fluorescence quantum yields, high molar absorp-
tivities, excellent thermal and photostability, chemical
inertness and electron accepting properties.1 Due to
these desirable attributes, PDIs have been utilized in a
variety of applications in the burgeoning field of organic
electronics such as organic photovoltaics,2 field effect
transistors,3 biosensors,4 organic light emitting diodes,5
optical switches,6 and molecular wires.7 PDIs have also
been used in many other applications such as artificial
photosynthetic systems8 through controlled supramolecular
architectures via their high propensity for πÀπ stacking.9
While the potential of the parent perylene tetracarboxylic
dianhydride (PTCD) was known for decades, its utility
was limited due to complete insolubility in organic solvents.
PTCD becomes soluble via synthetic modification to N-alkyl
(1) (a) Huang, C.; Barlow, S.; Marder, S. R. J. Org. Chem. 2011, 76,
2386–2407 and references therein. (b) Ajayaghosh, A.; George, S. J.;
€
Schenning, A. P. H. J. Top. Curr. Chem. 2005, 258, 83-118. (c) Wurthner,
F. Chem. Commun. 2004, 2004, 1564–1579 and references therein. (d)
Jones, B. A.; Ahrens, M. J.; Yoon, M.-H.; Facchetti, A.; Marks, T. J.;
Wasielewski, M. R. Angew. Chem., Int. Ed. 2004, 43, 6363–6366. (e)
Dimitrakopoulos, C. D.; Malenfant, P. R. L. Adv. Mater. 2002, 14, 99–
117.
(2) (a) Tang, C. W. Appl. Phys. Lett. 1986, 48, 183–185. (b) Schmidt-
Mende, L.; Fechtenkotter, A.; Mullen, K.; Moons, E.; Friend, R.;
Mackenzie, J. Science 2001, 293, 1119–1122.
(6) O’neil, M. P.; Niemczyk, M. P.; Svec, W. A.; Gosztola, D.;
Gaines, G. L., III; Wasielewski, M. R. Science 1992, 257, 63–65.
(7) Elemans, J. a. a. W.; Van Hameren, R.; Nolte, R. J. M.; Rowan,
A. E. Adv. Mater. 2006, 18, 1251–1266.
(8) Rodriguez-Morgade, M. S.; Torres, T.; Atienza-Castellanos, C.;
Guldi, D. M. J. Am. Chem. Soc. 2006, 128, 15145–15154.
€
€
(9) Wurthner, F.; Kaiser, T. E.; Saha-Moller, C. R. Angew. Chem.,
Int. Ed. 2011, 50, 3376–3410.
(3) Chen, Z.; Debije, M. G.; Debaerdemaeker, T.; Osswald, P.;
(10) (a) Queste, M.; Cadiou, C.; Pagoaga, B.; Giraudet, L.; Hoffmann,
N. New J. Chem. 2010, 34, 2537. (b) Chao, C.-C.; Leung, M.-K.; Su, Y. O.;
Chiu, K.-Y.; Lin, T.-H.; Shieh, S.-J.; Lin, S.-C. J. Org. Chem. 2005, 70,
4323–4331. (c) Zhao, Y.; Wasielewski, M. R. Tetrahedron Lett. 1999, 40,
7047–7050.
€
Wurthner, F. ChemPhysChem 2004, 5, 137–140.
(4) Wang, B.; Yu, C. Angew. Chem., Int. Ed. 2010, 49, 1485–1488.
(5) Angadi, M. A.; Gosztola, D.; Wasielewski, M. R. Mater. Sci.
Eng., B 1999, 63, 191–194.
r
10.1021/ol2019407
Published on Web 08/10/2011
2011 American Chemical Society

or aryl PDIs and/or by modification of the “bay” region
(1,6,7,12 positions).10 Most research groups increase solubi-
lity by addition of bulky groups at the imide and fine-tune the
electronic properties by functionalization of the bay region.
Synthetically, however, this methodology has challenges that
need to be addressed.
In 1997, BASF reported a procedure for the bromina-
tionof PTCD 1 atthe 1,7 positionsfollowed byimidization
to afford PDIs of type 3.11 Upon formation of soluble
PDIs, the bay bromines undergo a variety of substitution
and cross-coupling reactions.1a,12 Through this synthetic
route PDIs were incorporated into dendrimers, organo-
gels, and polymers, among others.13 Unfortunately, all
PDI publications prior to 2004 (and even some after) that
reference BASF’s bromination procedure for the synthesis
of 1,7À3 should be regarded as using inseparable mixtures
of 1,6 and 1,7 PDI derivatives.
synthetic handle for appending a myriad of supramolecular
motifs for further self-assembly.18 Following imidization and
bay functionalization, PDIs can be converted back to the
corresponding PTCDs, without losing solubility, for addi-
tional synthetic manipulation. In the quest to facilely obtain
large quantities of pure 1,7 and 1,6 substituted PDIs, we
investigated various neutral bay substituents to facilitate
chromatographic separation of the regioisomers.
The syntheses of all reported compounds began with
commercially available PTCD-1 and are outlined in
Schemes 1 and 2. Imidization of 1 with 3-aminopentane
in imidazole at 140 °C afforded diimide 2 in 88% isolated
yield. Bromination was achieved by heating diimide 2 with
an excess of Br2 (68 equiv) in CH2Cl2 for 48 h.19 Under
these conditions, the authors reported exclusive formation
of 1,7/1,6À3. In our hands, however, both the regioiso-
meric mixture (1,7/1,6À3) (70% yield) and monobromo
4 (28% yield) were formed (Scheme 1). The isolated yield
of 1,7/1,6À3 was increased to 85% and the formation of
monobromo 4 was reduced to 10% by prolonged reaction
times. Pure 1,7À3 was isolated from the mixture follow-
€
In 2004, Wurthner et al. drew attention toward the
regioisomeric impurity of dibromo PDIs (3) and by deduc-
tion, dibromo PTCD.14 Under the brominating conditions
reported by BASF, the two regioisomers are actually
synthesized in a ratio of ∼4:1. Unless the seminal 2004
€
ing Wurthner’s procedure of repetitive recrystallization
€
Wurthner et al. manuscript is referenced or there is pointed
(7 weeks, 24% isolated yield).
To facilitate chromatographic separation,20 we chose
the base stable bulky triphenyl propyne (TPP)21 group for
bay substitution. Standard Sonogashira coupling condi-
tions of 1,6 enriched 1,7/1,6À3 afforded the isomeric mix-
ture of 1,7/1,6À5a in 87% combined yield (Scheme 1).22
1,7À5a and 1,6À5a were easily separated by slow column
chromatography over 7 days in good yield. The first band
isolated was characterized as 1,6À5a (19% yield) and the
second band was characterized as 1,7À5a (58% yield).
Saponification of 1,7À5a or 1,6À5a afforded 1,7À6a or
1,6À6a in 73 or 75% respective yields (Scheme 2).23
It is .known that substitution at the bay region de-
forms the perylene core from planarity and can negatively
mention of removal of the 1,6-PDI impurity, it is difficult
to determine whether or not the regioisomeric “problem”
has been addressed.15
€
Although Wurthner’s method of separation is very
useful, it is also time-consuming (6À8 weeks for pure
1,7À3) and not amenable for separation of large quantities.
Additionally, 1,6À3 cannot be isolated in pure form via the
recrystallization process, and subsequently, little is known
about its individual spectroscopic properties. There are only a
few reports of isolation and characterization of both 1,6 and
1,7 bay substituted PDIs.16 Herein, we present our approach
for the synthesis, isolation and characterization of soluble 1,7
and 1,6 bay substituted derivatives of PDI and PTCD.17
The spectral properties of PDIs change upon bay func-
tionalization but, in solution, are only moderately affected
by imide functionalization.1c The imide is hence an attractive
Scheme 1
€
(11) Bohm, A.; Arms, H.; Henning, G.; Blaschka, P. (BASF AG)
German Pat. DE 19547209 A1, 1997; Chem. Abstr. 1997, 127, 96569g.
(12) (a) Zhao, Y. Tetrahedron Lett. 1999, 19. (b) Rohr, U.; Kohl, C.;
€
Mullen, K.; Van De Craats, A.; Warman, J. J. Mater. Chem. 2001, 11,
1789–1799. (c) Wescott, L. D.; Mattern, D. L. J. Org. Chem. 2003, 68,
10058–10066.
(13) (a) Sugiyasu, K.; Fujita, N.; Shinkai, S. Angew. Chem., Int. Ed.
ꢀ
2004, 43, 1229–1233. (b) Serin, J. M.; Brousmiche, D. W.; Frechet,
J. M. J. Chem. Commun. 2002, 2605–2607. (c) Ego, C.; Marsitzky, D.;
€
Becker, S.; Zhang, J.; Grimsdale, A. C.; Mullen, K.; Mackenzie, J. D.;
Silva, C.; Friend, R. H. J. Am. Chem. Soc. 2002, 125, 437–443. (d)
€
Thelakkat, M.; Posch, P.; Schmidt, H.-W. Macromolecules 2001, 34,
€
7441–7447. (e) Wurthner, F.; Thalacker, C.; Diele, S.; Tschierske, C.
Chem.;Eur. J. 2001, 7, 2245–2253.
€
(14) Wurthner, F.; Stepanenko, V.; Chen, Z.; Saha-Moeller, C. R.;
Kocher, N.; Stalke, D. J. Org. Chem. 2004, 69, 7933–7939.
(15) Sivamurugan, V.; Kazlauskas, K.; Jursenas, S.; Gruodis, A.;
Simokaitiene, J.; Grazulevicius, J. V.; Valiyaveettil, S. J. Phys. Chem. B
2010, 114, 1782–1789.
(16) (a) Dubey, R. K.; Efimov, A.; Lemmetyinen, H. Chem. Mater.
2011, 23, 778–788. (b) Fan, L.; Xu, Y.; Tian, H. Tetrahedron Lett. 2005,
46, 4443–4447. (c) Goretzki, G.; Davies, E. S.; Argent, S. P.; Warren,
J. E.; Blake, A. J.; Champness, N. R. Inorg. Chem. 2009, 48, 10264–
10274.
(17) Yuan, Z.; Li, J.; Xiao, Y.; Li, Z.; Qian, X. J. Org. Chem. 2010, 75,
3007–3016.
Org. Lett., Vol. 13, No. 17, 2011
4725

To our surprise, the two regioisomers 1,7À5c and
1,6À5c were easily separable by conventional column
chromatography in just a few hours. Contrary to the
original hypothesis, bay substitution with bulky groups is
not a requirement for facile separation of PDIs. Alkyl
substituted PDIs 1,7À5c and 1,6À5c were converted to the
respective PTCDs via saponification to afford 1,7À6c and
1,6À6c in 51 and 62% yields (Scheme 2). All compounds
(1,7/1,6À5,6) exhibit excellent solubility in a variety of
solvents such as CH2Cl2, CHCl3, toluene, THF, DMSO,
acetone etc.
Scheme 2
The steady state absorption spectra of all 1,7/1,6 PDI
and PTCDderivatives were obtainedinCH2Cl2 (Figure1).
The values of the absorption maxima and the correspond-
ing molar extinction coefficients are given in Table 1.
Compounds with alkynes appended at the bay region
(1,7/1,6À5a,b-6a) have an absorption maxima between
545À555 nm, which is red-shifted from the parent PDI 2
(524 nm). Upon reduction, the absorption maxima hypso-
chromically shift to 520 and 521 nm respectively. The
moderate blue shifts of 1,7/1,6À5c and 6c are due to
deformation by the alkyl groups as it is known that
deformation from planarity of the perylene core results is
hypsochromic shifts.27 We attribute these shifts primarily
to steric and not electronic effects as the neutral hexyl
substituted compounds, 1,7/1,6À5c and 6c, are blue-
shifted even when compared to electron withdrawing bay
substituted PDIs (ÀCN, Cl, Br)1d,12b and have similar λmax
as 1,7 dinitro substituted PDIs,28 most of which have been
shown via crystallography to be deformed from planarity.
However, it is difficult to ascertain to what extent electronic
and/or steric effects contribute to shifts in the absorption
spectra of PDIs and PTCDs.
affect solid-state packing and subsequent electron mo-
bilities.24 We were subsequently interested in append-
ing less bulky groups. 1-Hexyne was cross-coupled
to the bay region of the regioisomeric mixture of 3
(Scheme 1).2b,12b,25 As expected, 1,7À5b and 1,6À5b
could not be differentiated by TLC or separated by
column chromatography.
Using 1,7À3 obtained from crystallization and subse-
quent Sonogashira cross-coupling, 1,7À5b was isolated in
83% yield. We attempted to obtain the corresponding
PTCD 1,7À6b by saponification, however, the harsh basic
conditions decomposed 1,7À5b and no isolable products
were obtained. To circumvent this problem, the regioisomeric
mixture of 1,7/1,6À5b was subjected to palladium-catalyzed
hydrogenation.26
(18) Abbel, R.; Grenier, C.; Pouderoijen, M. J.; Stouwdam, J. W.;
Leclere, P. E. L. G.; Sijbesma, R. P.; Meijer, E. W.; Schenning, A. P. H. J.
J. Am. Chem. Soc. 2009, 131, 833–843. (b) Wurthner, F.; Thalacker, C.
Adv. Mater. 1999, 11, 754–758.
(19) Rajasingh, P.; Cohen, R.; Shirman, E.; Shimon, L. J. W.;
Rybtchinski, B. J. Org. Chem. 2007, 72, 5973–5979.
(20) Jimenez, A. J.; Spaenig, F.; Rodriguez-Morgade, M. S.; Ohkubo,
K.; Fukuzumi, S.; Guldi, D. M.; Torres, T. Org. Lett. 2007, 9, 2481–
2484.
(21) Oyler, R. E.; Ketz, B. E.; Glass, T. E. Tetrahedron Lett. 2000, 41,
8247–8250.
(22) Used the mother liquor from the successive recrystallization of
€
Wurthner’s recystallization procedure. 1,6À3 was enriched beyond the
4:1 ratio of brominated 1,7/1,6À3 to 7:3 (see Supporting Information).
(23) 37Goltner, C.; Pressner, D.; Mullen, K.; Spiess, H. Angew.
Chem., Int. Ed. 1993, 32, 1660–1662.
€
(24) (a) Chen, Z.; Baumeister, U.; Tschierske, C.; Wurthner, F.
Figure 1. Steady state absorption spectra of PTCDs and PDIs
(1.0 Â 10À5 M, 25 °C, CH2Cl2). Blue: R = TPP. Red: R =
hexyne. Black: R = hexyl. 1,7-PDIs = dot-dash line; 1,6-
PDIs = dashed line; 1,7-PTCDs = solid line; 1,6-PTCDs =
dotted line.
Chem.;Eur. J. 2007, 13, 450–465. (b) Osswald, P.; Wuerthner, F. J.
Am. Chem. Soc. 2007, 129, 14319–14326. (c) Gsanger, M.; Oh, J. H.;
€
Konemann, M.; Hoffken, H. W.; Krause, A.-M.; Bao, Z.; Wurthner, F.
€
€
€
Angew. Chem., Int. Ed. 2009, 740–743.
€
(25) Nolde, F.; Pisula, W.; Muller, S.; Kohl, C.; Mullen, K. Chem.
€
Mater. 2006, 18, 3715–3725.
4726
Org. Lett., Vol. 13, No. 17, 2011

Table 1. Physical Data for All PDIs and PTCDs Synthesized
compounda
λmax [nm]
ε [MÀ1 cmÀ1 b
]
λ
em [nm]c
Td [°C]d
Tc [°C]e
Tm [°C]e
1,7À5a
1,6À5a
1,7À5b
1,7À5c
1,6À5c
1,7À6a
1,6À6a
1,7À6c
1,6À6c
552
549
549
521
520
550
546
515
514
59490
48200
57620
61210
57750
54140
49420
43770
57110
571
566
570
542
541
571
565
535
536
380
375
N.D.f
357
357
381
390
340
340
N.D.
N.D.
N.D.
N.D.
N.D.
NAg
NA
N.D.
N.D.
N.D.
N.D.
N.D.
NA
NA
248
207
242
213
a Optical properties measured in CH2Cl2. b Determined at λmax
. .
c Excited at λmax d Determined by TGA. e Determined by DSC. f N.D. = not
determined. g NA = no observed phase transistions in temperature range investigated.
The predominant difference between alkynyl substi-
tuted 1,7 and 1,6 regioisomers is evident at ≈295 nm and
≈330 nm. We attribute the absorbances at ≈295 nm to
the 1,7 substitution pattern with alkyne conjugation
while the ≈330 nm absorption band is attributed to
conjugated 1,6 substitution. Neither of the absorbances
are present in the reduced compounds (Figure 1). 1,
6/1,7À5c and 6c do not show any significant differences
between the two regioisomers. Additionally, converting
PDIs 1,7/1,6À5c to PTCDs 1,7/1,6À6c does not induce
any significant changes in the absorption spectra.
PTCD pairs 1,7/1,6À6a or 1,7/1,6À6c have nearly iden-
tical λmax in solution, however, these regioisomeric pairs
exhibit solid state-chromy indicative of dissimilar πÀπ
stacking in the solid state.29
The emission spectra of all PDIs and PTCDs were
recorded and the wavelength of the emission maxima are
given in Table 1. The emission spectra are typical for
PDIs30 and do not exhibit any major differences between
the 1,7 and 1,6 regioisomers. As with the absorption
spectra there is little difference between the bay substituted
PDIs and PTCDs. Stokes shifts are also similar among the
compounds and only minimal solvatochromism is ob-
served (see Supporting Information).
much lower decomposition onset temperatures (340À
360 °C). We compared the morphological behavior of
1,7/1,6À6a and 6c, with differential scanning calorime-
try (DSC). The corresponding values are given in Ta-
ble 1. PTCDs 1,7/1,6À6a do not show any thermal
transitions in the temperature range investigated
(25À300 °C). DSC of 1,7/1,6À6c show the presence of
both melting and crystallization temperatures. In com-
parison to the TPP subsituted compounds, PTCDs 1,
7/1,6À6c show phase transitions presumably due to the
presence of the hexyl chains, which impart mobility and
thus afford melting and crystalline phase transitions.
In summary, we have reported on the syntheses, facile
separation techniques and properties of 1,7 and 1,6 regio-
isomersof bayappended PDIs. Inaddition, wereportedon
the syntheses and properties of both 1,7 and 1,6 bay
substituted PTCDs. Alkyl bay substituted PDIs and
PTCDs had previously been unreported and have attrac-
tive spectral and solubility properties. Additional solid
state and electrochemical data will be published in due
course in a corresponding full manuscript.
Acknowledgment. We acknowledge the College of
Arts and Sciences and the Department of Chemistry at
Oklahoma State University for financial support.
The thermal stability of PDI and PTCD derivatives
were measured with thermogravimetric analysis (TGA)
(Table 1). Alkyne substituted PDIs and PTCDs 1,
7/1,6À5a and 6a have decomposition onset tempera-
tures g375 °C. Alkyl substituted 1,7/1,6À5c and 6c have
Supporting Information Available. Full characteriza-
tion details and supporting data. This material is avail-
able free of charge via the Internet at http://pubs.acs.org.
(26) Mandal, P. K.; Mcmurray, J. S. J. Org. Chem. 2007, 72, 6599–
6601.
(29) Klebe, G.; Graser, F.; Hadicke, E.; Berndt, J. Acta Crystallogr.
1989, 1–9.
€
(27) (a) Rohr, U.; Schlichting, P.; Bohm, A. Angew. Chem., Int. Ed.
1998, 37, 1434–1437. (b) Ilhan, F.; Tyson, D. S.; Stasko, D. J.; Kirschbaum,
K.; Meador, M. A. J. Am. Chem. Soc. 2006, 128, 702–703.
ꢀ
(30) Baggerman, J.; Jagesar, D. C.; Vallee, R. a. L.; Hofkens, J.; De
Schryver, F. C.; Schelhase, F.; Vogtle, F.; Brouwer, A. M. Chem.;Eur.
€
(28) Chen, K.-Y.; Chow, T. J. Tetrahedron Lett. 2010, 51, 5959–5963.
J. 2007, 13, 1291–1299.
Org. Lett., Vol. 13, No. 17, 2011
4727