Twisted, Z-shaped perylene bisimide

Article abstract of DOI:10.1021/ja056912o

The first derivative of a new class of perylene bisimide chromophores, N,N′-bis(octyl)-3,9-bis(phenyl)perylene-1,2,7,8-tetracarboxyl bisimide, 1, has been synthesized and its fundamental photophysical and electrochemical properties assessed. The extended,

Full text of DOI:10.1021/ja056912o

Published on Web 12/23/2005
Twisted, Z-Shaped Perylene Bisimide
Faysal Ilhan,†,‡ Daniel S. Tyson,†,‡ Daniel J. Stasko,§ Kristin Kirschbaum, and Michael A. Meador*,†
Polymers Branch, Materials and Structures DiVision, NASA Glenn Research Center, 21000 Brookpark Road,
CleVeland, Ohio 44135, Ohio Aerospace Institute, 22800 Cedar Point Road, CleVeland, Ohio 44142, The UniVersity
of Southern Maine, Lewis-Auburn College, 51 Westminster Street, Lewiston, Maine 04240, and Department of
Chemistry, UniVersity of Toledo, Toledo, Ohio 44306
Received October 21, 2005; E-mail: Michael.A.Meador@nasa.gov
Perylene bisimides have found use in a wide range of applica-
tions, including electron-transfer systems,1 liquid crystals2 and other
supramolecular assemblies,3 photovoltaics,4 and fluorescent sensors.5
Interest in these compounds is due to their high fluorescence
quantum yields and tunable absorption and emission properties. A
diverse library of linear perylene bisimides (Figure 1) has been
prepared from commercially available perylene anhydride or
dianhydride and a wide array of amines via conventional imidization
chemistry. Alkylamines or amine-terminated poly(ethylene glycol)s
Figure 1. Linear and Z-shaped perylene bisimides.
have been used to enhance solubility and/or impart liquid crystal-
linity. Approaches have also been reported to asymmetrically
substituted bisimides6 containing both a solubilizing group and an
active unit, e.g. an electron donor or acceptor, to endow a specific
function to the perylene. Significant attention has also been given
to attaching pendant groups directly to the perylene core,7 which
can dramatically alter excited-state properties.
We are excited to report the first example of a nonlinear or
Z-shaped perylene bisimide, 1. This new bisimide differs from
conventional linear systems in both the position and size of the
imide rings. In addition, steric interactions between the imide
carbonyls and hydrogens on C-6 and C-12 result in a twisting of
the perylene ring system (vide infra). These changes, however,
produce only minor electronic perturbations of the perylene bisimide
1, and the favorable properties observed in linear systems, including
visible absorption/emission and high fluorescence quantum yields,
have been retained.
Figure 2. Diels-Alder trapping of o-xylyenol, 3.
Scheme 1. Synthesis of Perylene Bisimide Precursor, Bisadduct 8
The synthesis of 1 employs a well-known photochemical
reaction; the Diels-Alder trapping of o-methylphenyl ketone
derived o-xylyenols (photoenols). Yang and Rivas first reported
that cycloaddition of dimethyl acetylenedicarboxylate with o-
xylyenol 3, generated by photolysis of o-methylbenzophenone 2,
produced tetralin 4 in 65% yield (Figure 2).8 This chemistry has
been widely employed in the synthesis of fused six-membered ring
systems.8 Most of these applications have utilized ketone precursors
capable of generating a single o-xylylenol.
We have extended this chemistry to diketones, such as 5, which
are capable of generating two distinct o-xylylenols and have found
that this powerful synthetic methodology offers a versatile, re-
giospecific, high-yield route to a variety of highly substituted
anthracenes, phenanthrenes, and polymers.9 We have now turned
our attention to its use in the synthesis of novel polycyclic aromatic
hydrocarbons, such as 1.
that the more likely pathway to bisadduct 8 involves enolization
of 5 and trapping to form monoadduct 7 followed by a second
enolization/trapping sequence.10 Subsequent dehydration and aro-
matization gave N,N′-bis(octyl)-3,9-diphenylperylene-1,2,7,8-
tetracarboxyl bisimide 1 as an orange solid in 18% overall yield
from 5.
Z-shaped perylene bisimide 1 is soluble in polar organic solvents.
Room-temperature absorption and emission spectra of 1 are shown
in Figure 3. Compound 1 has an absorption λmax near 491 nm with
an extinction coefficient of 29,000 M-1cm-1 11
. Fluorescence of 1
exhibits a Stokes’ shift of 26 nm (λmax ) 517 nm) and a quantum
yield of 0.67.11 Intense green emission is observed both in solution
and polystyrene films (inset of Figure 3). Emission from 1 does
not exhibit solvatochromism. Room-temperature fluorescence decay
measurements in CH2Cl2 revealed a single-exponential lifetime of
5.01 ns, consistent with a singlet excited state. Solid-state emission
is bright orange, indicative of exciplex formation. Cyclic voltam-
metry on 1 in CH2Cl2, using a silver wire quasi-reference electrode
Thus, irradiation of 5 in the presence of 2.2 equiv of N-
octylmaleimide 6 produced bisadduct 8 in 49% yield as a mixture
of diastereomers (Scheme 1). While formation of bis-o-xylylenol
intermediate 9 is possible, our work with related diketones suggests
† NASA Glenn Research Center.
‡ Ohio Aerospace Institute.
§ University of Southern Maine, Lewiston Auburn College.
University of Toledo.
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J. AM. CHEM. SOC. 2006, 128, 702-703
10.1021/ja056912o CCC: $33.50 © 2006 American Chemical Society

C O M M U N I C A T I O N S
have a broad range of applications including electron transfer
systems, molecular sensors and electronics, and liquid crystalline
materials. We are currently exploring these avenues.
Acknowledgment. We thank Daniel A. Scheiman and Javier
Santos for helpful discussions. F.I. and D.S.T. are supported by
NASA Cooperative Agreements NCC3-887 and NCC3-1089. This
work was funded by the Alternative Energy Foundations Technolo-
gies subproject of the Low Emissions Alternative Propulsion project
at NASA Glenn. We thank the College of Arts and Sciences of the
University of Toledo for generous financial support of the X-ray
diffraction facility.
Note Added after ASAP Publication. After this paper was
published ASAP on December 23, 2005, the Scheme 1 title was
corrected. The corrected version was published ASAP January 6,
2006.
Figure 3. Absorption (solid line) and normalized emission (425 nm excit)
spectra (dotted line) of 1 in CH2Cl2. (Inset): Emission from 1 in a pure
microcrystalline sample (left), in a polystyrene film (center), and in CH2-
Cl2 solution (right) excited with a hand-held, broadband UV source.
Supporting Information Available: Synthetic and crystallographic
details. This material is available free of charge via the Internet at http://
pubs.acs.org.
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