N -1- and N-2-anthryl succinimide derivatives: C-N bond rotational behaviors and fluorescence energy transfer

Article abstract of DOI:10.1021/jo200665v

New rigid bicyclic N-anthrylsuccinimide 1a, 1b, 2a, and 2b were prepared. The C_aryl-N_imide bond rotational barriers, intra/intermolecular arene-arene interactions, and photophysical properties were investigated. The rotational behaviors are more significantly controlled by the position of C_aryl-N_imide connection than the sidewall framework. The fluorescence energy transfer (Φ_ET) in 1a and 1b was estimated to be 61% and 53%, respectively. The difference is attributed to the position of C_aryl-N_imide connection, which directly influences the relative orientation of donor (naphthalene) and acceptor (anthracene).

Full text of DOI:10.1021/jo200665v

NOTE
pubs.acs.org/joc
N-1- and N-2-Anthryl Succinimide Derivatives: CÀN Bond
Rotational Behaviors and Fluorescence Energy Transfer
Teh-Chang Chou,*,† Ren-Tsung Wu,† Kung-Ching Liao,‡ and Chun-Hung Wang‡
†Department of Applied Chemistry, Chaoyang University of Technology, Wufong, Taichung, 41369, Taiwan
‡Institute of Chemistry, Academia Sinica, No. 128, Sec. 2, Academia Road, Taipei 115, Taiwan
S Supporting Information
b
ABSTRACT: New rigid bicyclic N-anthrylsuccinimide 1a, 1b,
2a, and 2b were prepared. The CarylÀNimide bond rotational
barriers, intra/intermolecular areneÀarene interactions, and
photophysical properties were investigated. The rotational
behaviors are more significantly controlled by the position of
CarylÀNimide connection than the sidewall framework. The
fluorescence energy transfer (ΦET) in 1a and 1b was estimated
to be 61% and 53%, respectively. The difference is attributed to
the position of CarylÀNimide connection, which directly influ-
ences the relative orientation of donor (naphthalene) and acceptor (anthracene).
ecently, investigations toward a better understanding of
weak noncovalent interactions involving aromatic rings has
1b (90%). Similar condensation reactions of anhydride 3 with 7a
or 7b furnished N-anthrylsuccinimides 2a (90%) and 2b (91%),
respectively. All the newly synthesized N-anthrylsuccinimides
(1a,b and 2a,b) were fully characterized (see Experimental
Section) and further unequivocally established via the X-ray
crystallographic analysis (vide infra).
R
led to design small molecular systems featuring rigid polycyclic
N-arylsuccinimide scaffolds, taking advantage of their concave
molecular geometry that can fasten the N-aryl substituent closely
interacting with the sidewall arene moiety.1À12 The areneÀarene
interactions between aryl sidewall and N-aryl moiety could
subsequently affect molecular properties, such as the conforma-
tional preferences,1À5 molecular packing motifs in solid states,6,7
and intramolecular charge/energy transfer,8À10 granting oppor-
Because of the steric interaction of the N-aryl hydrogens with
the imide carbonyl groups, the aryl group is prevented from being
coplanar with the plane of succinimide ring, resulting in affecting
the effectiveness of electron delocalization of the unshared
electron pair on the nitrogen atom to the aryl ring, as well as
the rotation about the single bond that joins the aryl ring to the
nitrogen atom. The restricted rotation of the N-anthryl ring
about CarylÀNimide bond in 1a/1b (and 2a/2b) would give rise
to two distinct stereoisomers having unfolded-conformation
(exo-) and folded-conformation (endo-), designated by the
relative orientation (syn or anti) between the naphthalenyl
moiety bearing C-9 and the methano-bridge, as depicted in
Figure 1. The CarylÀNimide bond rotational barriers are expected
to be influenced by the attachment position of anthryl carbon
(C-1 or C-2) to the nitrogen atom of succinimide ring and the
presence of aryl sidewall. We thus embarked on investigating the
rotational barriers of 1 and 2 by using 1H NMR spectroscopy and
computational methods.
tunity to scrutinize the intra/intermolecular π π (face-to-
3 3 3
face) and CH π (edge-to-face) interactions.11,12 In this con-
3 3 3
text, we designed and prepared rigid bicyclic N-anthrylsuccini-
mides 1a, 1b, 2a, and 2b (shown in Scheme 1). These
succinimides are characterized by two structural features, the
presence or absence of diphenylnaphthalene sidewall (1a vs 2a
and 1b vs 2b) and the attachment position of Nimide to
anthracene ring (1a vs 1b and 2a vs 2b). The effects of these
features were evaluated by the intra/intermolecular areneÀarene
interactions relating to the rotational behaviors of N-anthryl ring
about CarylÀNimide bond, the molecular packing in the solid
state, and photophysical properties. Herein, we report the results.
As shown in Scheme 1, the synthesis of N-anthrylsuccinimides
1a, 1b, 2a, and 2b started from the DielsÀAlder reaction of
bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (3)13 and
1,3-diphenylisobenzofuran (4), followed by the acid-catalyzed
dehydration (aromatization) of the resulting adduct 5 (without
isolation) to give diphenylnaphthalene-fused bicyclic anhydride
6 (overall yield 77%). The condensation reaction of 6 with
1-aminoanthracene (7a) or 2-aminoanthracene (7b) was then
carried out in refluxing acetic acid, catalyzed by Zn(OAc)2,8,13 to
afford the corresponding N-anthrylsuccinimides 1a (96%) and
The assignments of the absorption signals for the protons
were made using intensity, chemical shift, and splitting pattern,
and further supported by COSY experiments (Figures S1ÀS10,
Supporting Informations, SI). When crystalline N-(1-anthryl)-
succinimides 1a and 2a were, respectively, dissolved in cold
Received: April 13, 2011
Published: July 05, 2011
r
2011 American Chemical Society
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NOTE
Scheme 1
(δ 5.56) and H-3 (δ 6.96) of endo-1a were found to display
absorption signals at lower magnetic field as compared with the
respective protons of exo-1a, because they swung away from the
shielding zone of the sidewall aromatic rings. Meanwhile, the
anthryl H-10 moved into the shielding zone, showing signal at
higher field for endo-1a (δ 8.40) relative to that for exo-1a (δ
8.45). The results of 1H NMR equilibration study led us to attain
the time-dependent ratios of exo- and endo-conformers and
therefore the rotational barriers of CarylÀNimide bond for 1a and
2a calculated according to the equations introduced by Shimizu
et al.1,2,16 The rotational barriers for 1a and 2a were approxi-
mately 92.0 and 91.1 kJ/mol, respectively, which were supported
by the results of theoretical calculations (vide infra). At equilib-
rium (308 K), the exo/endo ratios of compounds 1a and 2a were
observed to be 65:35 and 55:45, respectively, implying that the
unfolded exo-conformation is more stable than the folded endo-
conformation. The higher rotational barrier and the bigger
difference in population of exo/endo conformers for 1a than
for 2a may be ascribed to the larger steric hindrance between the
1-anthryl group and the diphenylnaphthalene sidewall.
Figure 1. Two conformations, exo- and endo-, of 1a and 1b, resulting
from restricted rotation about the N-aryl single bond. The chemical shift
(δ) for H-1 of 1b changed from 6.44 at 303 K to about 6.25 at 213 K,
while that of H-3 remained unchanged.
1
On the contrary, the room-temperature H NMR spectra of
N-(2-anthryl)succinimides 1b and 2b, which remained un-
changed over time, showed signals ascribable to either exo- or
endo-conformer or rapidly interconverting conformers. The
diphenylnaphthalene-fused 1b was further investigated using
CD2Cl2 (ca. À20 °C) and immediately examined in a NMR
spectrometer at 253 K, the 1H NMR spectra indicated that they
existed predominately in one conformer (Figures S2a/S4a in SI).
They were assigned, respectively, the exo-conformers, exo-1a and
exo-2a, as depicted in Figure 1, suggested by their solid-state
structures (vide infra) and the relatively upfield located signals
for anthryl H-2 (1a, δ 5.11; 2a, δ 7.13) and H-3 (1a, δ 6.85) due
to anisotropic shielding by the sidewall aromatic rings or CdC
bond.14,15 The 1H NMR spectra of 1a and 2a were then recorded
at a constant temperature (308 K) at regular time intervals (5 min)
until the rotational process attained an equilibrium.
1
the variable-temperature H NMR technique.3,16 As shown in
Figure S14 in SI, the CarylÀNimide bond rotation was still rapid
and basically similar pattern of absorption signals was observed
even at temperature lowered to 183 K. The observed chemical
shifts were due to the “averaged” peaks. One signal worthy of
notice is the one-proton singlet at δ 6.44 due to the anthryl H-1
(see Figure 1), which broadened and moved upfield significantly
with decreasing temperature, and finally flattened out at 183 K
together with one-proton doublet at δ 6.41 (H-3).
We adopted the PCM/MP2/6-31G(d)//B3LYP/6-31G(d)
approximation to calculate the CarylÀNimide bond rotational
barrier in CH2Cl2 for each N-anthrylsuccinimide (Figures S15
and S16 in SI).3,17 For N-(1-anthryl)succinimides 1a and 2a, the
As shown in Figure S12 in SI, a new set of absorption signals
emerged and augmented in each spectrum of 1a, which was
attributed to the appearance of other conformer, the endo-
1
1a. The equilibration H NMR spectra of 2a behaved similarly
(Figure S13 in SI). As noted in Figure 1, the anthryl H-2
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NOTE
Scheme 2
Figure 2. ORTEP drawings of N-anthrylsuccinimides: (a) 1a, (b) 2a,
(c) 1b, and (d) 2b. The arrows indicate the succinimideÀanthracene
dihedral angles defined by C1ÀN2ÀC3ÀC4.
rotational barriers were estimated to be 98.6 and 85.8 kJ/mol,
1
respectively, comparable to the values derived from H NMR
for the “dimeric” structure. The crystal packing motifs for the
dimeric structures of 1a,b and 2a,b are shown in Figure S17 in SI.
equilibration study. On the other hand, the rotational barriers for
N-(2-anthryl)succinimides 1b and 2b were calculated to be 26.5
and 22.8 kJ/mol, respectively, in line with the results observed
in the variable-temperature 1H NMR spectra of 1b. On the basis
of the estimated rotational barriers, the CarylÀNimide bond
rotational rates of 1b and 2b are extremely rapid, and the half-
lives for their rotational motion are about 2.5 ns and 0.55 ns at
298 K, respectively. However, the CarylÀNimide bond rotational
behaviors of 1a and 2a are more restricted and relatively slower,
and the time scales for their half-lives are about 12.6 min and
8.6 min at 298 K, respectively.1 The results from calculations have
also shown that CarylÀNimide bond rotational behaviors are more
influenced by the position of Nimide attachment due to the steric
hindrance between succinimide carbonyl groups and N-anthryl ring.
The solid-state structures of N-anthrylsuccinimides (1a,b and
2a,b) are shown in Figure 2. The crystal structures of 1a and 2a
displayed similar exo-conformation with the succinimideÀ
anthracene dihedral angles measured to be 67.92° and 63.30°,
respectively (Figure 2a,b).11 No significant intramolecular inter-
action between the anthryl ring and the sidewall aromatic rings or
CdC bond was observed in the crystal structures of 1a and 2a.
On the other hand, probably due to the consequence of addi-
tional steric interaction between the N-aryl hydrogen (H-1
and H-3) and the imide carbonyl groups, the succinimideÀ
anthracene dihedral angles in 1b and 2b were found to be larger,
amounting to 87.19° and 77.18°, respectively (Figure 2c,d). In
the crystal structure of 1b (Figure 2c), the anthryl ring is located
in close proximity to the diphenylnaphthalene sidewall suitable
for H-3 of anthracene ring to exert an attractive intramolecular
A
weak intermolecular
distance 3.5 Å, centroid-to-centroid distance 6.08 Å) and an
intermolecular CH π interaction between anthracene rings
π
π interaction (interplanar
3 3 3
3 3 3
π = 2.78 Å) were observed for 2a and 2b, respectively
(dH
3 3 3
(Figure S18c,d in SI). In contrast, the dimeric structure of 1a is
realized by the CH
π (edge-to-face) interaction17À21 be-
3 3 3
tween anthracene ring of one molecule of 1a and phenyl ring of
another (dH = 2.95 Å), Figure S17a in SI. However, as
π
3 3 3
shown in Figure S17b in SI, two molecules of 1b align in N-
style, having their anthracene rings to perform an effective
intermolecular π
π (face-to-face) interaction with an interpla-
3 3 3
nar distance of 3.5 Å and a centroid-to-centroid distance of 3.82 Å. It is
worthy to note that intermolecular close contacts with distances of
about 2.5 Å between the CdO of the succinimide ring and the aryl
hydrogen were found to reinforce the crystal packing motifs of 1a, 1b,
and 2a.
The anti-(head-to-tail), π π stacking motif of 1b (Figure
3 3 3
S17b in SI) prompted us to investigate its solid-state photo-
chemical behavior.22,23 Thus, when yellow crystals of 1b were
pulverized and irradiated using 365 nm-light for 2 h, the reaction
yielded a photodimeric product as pale brown powders of low
solubility. The assignment of anti-(head-to-tail)-structure 8 to
the product (Scheme 2), rather than the syn-(head-to-tail)-
structure, was suggested by the π π stacking motif of mono-
3 3 3
mer 1b, and supported by the 1H NMR spectrum (Figure S8 in
SI), HÀH COSY (Figure S11 in SI), and the similarity of solid-
state UV absorption and emission spectra to those of anhydride 6
(Figure S18 in SI).24
CH
π (edge-to-face) interaction with aromatic sidewall
3 3 3 3
(dH π = 2.62 Å).18À21 Consequently, the plane of anthracene
The UV spectra of N-anthrylsuccinimides (1a,b and 2a,b) and
succinic anhydride 6 in CHCl3 (Figure S19 in SI) contain major
bands in the regions of 240À280, 280À310, and 330À390 nm,
characteristic of diphenylnaphthalene and anthracene chromo-
phores. Figure 3a,b shows the emission spectra under excitation
at wavelengths of either 295 or 365 nm.25 The fundamental
UV absorption and fluorescence properties are summarized in
Table S5 in SI. As shown in Figure 3a, the fluorescence spectra
of all N-anthrylsuccinimides are identical in shape, suggesting
3 3 3
ring in exo-1b is oriented nearly perpendicular to succinimide
ring with a succinimideÀanthracene dihedral angle larger than
that of 2b, which lacks an intramolecular CH π interaction
3 3 3
(Figure 2d).
Probably as a consequence of distinct sidewall structure and
varied orientation of the anthryl ring resulting from different
position of anthryl carbon (C-1 vs C-2) linked to Nimide, the N-
anthrylsuccinimides displayed dissimilar crystal packing motifs
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NOTE
influences the relative orientation of donor (naphthalene) and
acceptor (anthracene).
’ EXPERIMENTAL SECTION
Diphenylnaphthalene-Fused Bicyclic Anhydride (6). A so-
lution of cis-endo-bicyclo[2.2.1]hept- 5-ene-2,3-dicarboxylic anhydride
(3)13 (0.821 g, 5.0 mmol), and 1,3-diphenylisobenzofuran (4) (1.35 g,
5 mmol) in toluene (15 mL) was refluxed for 48 h.9 After completion of
DielsÀAlder cycloaddition, the reaction mixture was cooled to room
temperature, treated with trifluoroacetic acid (1.7 mL, 22 mmol), and
then heated under refluxing with a DeanÀStark trap for 16 h.12 The
reaction mixture was washed by 1.0 M NaHCO3 aqueous solution (5 mL Â
3), and the aqueous solution was extracted with CH2Cl2 (10 mL Â 3).
The combined organic layers were dried over anhydrous MgSO4,
filtered, and evaporated into dryness to afford a white powder (1.60 g,
77%) of 6: mp 281À283 °C (CHCl3/EtOH);1H NMR (CD2Cl2,
400 MHz, 298 K): δ 7.63À7.45 (m, 10H), 7.45À7.33 (m, 4H), 3.97
(s, 2H), 3.72 (s, 2H), 2.27 (d, J = 12 Hz, 1H), 1.99 (d, J = 12 Hz,
1H) ppm; 13C NMR (CDCl3, 100 MHz, 298 K): δ 170.2 (C), 136.2
(C), 134.3 (C), 132.5 (C), 131.2 (CH), 130.0 (CH), 128.3 (CH), 128.2
(CH), 127.7 (CH), 126.7 (CH), 126.0 (CH), 52.0 (CH2), 49.1 (CH),
46.0 (CH) ppm; MS (FAB) m/z 416.1 [M]+, 100%; HRMS (FAB) calcd
for C29H20O3 416.1412; obsd m/z 416.1404 [M]+. Anal. Calcd for
C29H20O3: C, 83.63; H, 4.84. Found: C, 83.79; H, 4.85.
Figure 3. Emission spectra (2 Â 10À5 M in CHCl3) of N-anthrylsucci-
nimides: (a) excited at λex 365 nm, and (b) 1a, 1b, and succinic
anhydride 6 excited at λex 295 nm. Fluorescence excitation (dash line)
spectra in CHCl3 normalized to match the absorption spectra (solid
line) in the anthracene region: (c) 1a (measured at 467 nm) and (d) 1b
(measured at 460 nm).
that the two spaced diphenylnaphthalene and anthracene chromo-
phores in 1a and 1b are essentially independent of each other.26,27
However, as evidently shown by Figure 3b, succinimides 1a and 1b
displayed intramolecular energy transfer phenomena from diphe-
nylnaphthalene to anthracene chromophores.28,29
The quantum efficiencies (ΦET) of intramolecular energy
transfer for 1a and 1b are estimated using the comparison of the
absorption spectra and corresponding fluorescence excitation
spectra (Figure S20 in SI). Because the naphthalene emission
least affected the emission wavelengths of 467 and 460 nm based
in Figure 3b, the fluorescence excitation profiles for 1a and 1b
measured respectively at these two wavelengths were normalized
to best match the absorption spectra in the anthracene region
Diphenylnaphthalene-Fused N-(1-Anthryl)succinimide
(1a). To a solution of bicyclic anhydride 6 (0.345 g, 0.83 mmol) and
1-aminoanthracene (0.160 g, 0.83 mmol) in acetic acid (6 mL) was
added zinc acetate dihydrate (0.018 g, 0.08 mmol). The reaction mixture
was refluxed for 2 h. After cooling, the reaction mixture was poured into
iceÀwater (120 mL). The aqueous solution was extracted with CH2Cl2
(20 mL Â 3), and the organic layers were combined and washed with
0.5 M NaHCO3 aqueous solution (20 mL Â 3). The organic layer was
dried over anhydrous MgSO4, filtered, and evaporated into dryness to
afford a dark brown solid. The crude product was chromatographed on
silica gel (CH2Cl2/Et2O = 10:1) yielding 1a as a yellow solid (0.468 g,
1
96%): mp >350 °C (CHCl3/EtOH); H NMR (CD2Cl2, 500 MHz,
257 K): δ 8.45 (s, 1H), 7.99À7.92 (m, 4H), 7.67À7.66 (m, 2H), 7.55À
7.43 (m, 12H), 7.26 (d, J = 5 Hz, 2H), 6.87À6.84 (m, 1H), 5.11 (d, J =
5 Hz, 1H), 4.06 (s, 2H), 3.82 (s, 2H), 2.38 (d, J = 10 Hz, 1H), 2.14 (d, J =
10 Hz, 1H) ppm; 13C NMR (CD2Cl2, 100 MHz, 298 K): δ 176.3 (C),
175.9 (C), 139.5 (C), 138.4 (C), 137.4 (C), 137.3 (C), 134.5 (C), 134.1
(C), 132.7 (C), 132.3 (C), 132.1 (C), 131.9 (C), 131.4 (CH), 131.1
(CH), 130.5 (CH), 130.1 (CH), 130.1 (CH), 129.9 (CH), 128.9 (C),
128.6 (CH), 128.3 (CH), 128.2 (CH), 128.0 (CH), 127.9 (CH), 127.5
(CH), 127.4 (CH), 127.2 (CH), 127.1 (CH), 126.7 (CH), 126.1 (CH),
126.0 (CH), 125.8 (CH), 125.6 (CH) 125.0 (CH), 124.1 (CH), 120.7
(CH), 120.1 (CH), 54.2 (CH2), 51.5 (CH2), 49.1 (CH), 48.5 (CH),
45.8 (CH), 45.4 (CH) ppm; MS (FAB): m/z 592.2 [M + H]+, 100%;
591.2 [M]+, 90%; HRMS (FAB) calcd for C43H30NO2: 592.2271; obsd
m/z 592.2280 [M + H]+. Anal. Calcd for C43H29NO2: C, 87.28; H, 4.94;
N, 2.37. Found: C, 87.32; H, 4.74; N, 2.13.
(330À390 nm) as shown in Figures 3c,d. The values of ΦET
,
defined as the ratio of the areas under the normalized excitation
and absorption curves, are calculated to be 61% and 53% for 1a
and 1b, respectively.29 The difference in energy transfer effi-
ciency in 1a and 1b may be attributed to the differences in the
distance, the relative orientation, and the HOMO energy level
between the acceptor (anthracene) and donor (diphenylnaphthalene)
chromophores,26 and the ratios of folded and unfolded confor-
mations, all of which are directly related to the attachment
position of Nimide to anthracene (C-1 vs C-2). The results sug-
gest that the N-1-anthryl group can serve as a more efficient
energy acceptor than the N-2-anthryl group.
In conclusion, a series of rigid bicyclic N-anthrylsuccinimide
1a, 1b, 2a, and 2b were prepared. The CarylÀNimide bond rota-
tional barriers of N-(1-anthryl)succinimide 1a and 2a are con-
siderably larger than those of N-(2-anthryl)succinimide 1b and
2b. The results have shown that the rotational behaviors and
conformational preference are more significantly controlled by
the position of CarylÀNimide connection (the steric effect of N-
anthryl and two carbonyl groups) than the sidewall framework.
The intramolecular naphthalene-to-anthracene fluorescence en-
ergy transfer was observed in 1a and 1b. The values of energy
transfer efficiency (ΦET) were estimated to be 61% and 53% for
1a and 1b, respectively. The difference in ΦET may be attributed
to the position of CarylÀNimide connection, which directly
Diphenylnaphthalene-Fused N-(2-Anthryl) Succinimide
(1b). To a solution of bicyclic anhydride 6 (0.345 g, 0.83 mmol) and
2-aminoanthracene (0.160 g, 0.83 mmol) in acetic acid (6 mL) was
added zinc acetate dihydrate (0.018 g, 0.08 mmol). The reaction mixture
was refluxed for 2 h. After cooling, the reaction mixture was poured into
iceÀwater (120 mL). The aqueous solution was extracted with CH2Cl2
(20 mL Â 3), and the organic layers were combined and washed with
0.5 M NaHCO3 aqueous solution (20 mL Â 3). The organic layer was dried
over anhydrous MgSO4, filtered, and evaporated into dryness to afford a
pale brown solid. The crude product was chromatographed on silica gel
(EtOAc/n-Hex = 1:2, and then CH2Cl2/Et2O = 10:1) yielding the 1b
as a yellow solid (0.442 g, 90%): mp 340À342 °C (CHCl3/EtOH).
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NOTE
1H NMR (CD2Cl2, 400 MHz, 298 K): δ 8.35 (s, 1H), 7.99À7.96
(m, 1H), 7.90À7.88 (m, 1H), 7.78 (d, J = 8 Hz, 1H), 7.74À7.69 (m,
3H), 7.55À7.31 (m, 14H), 6.44À641 (m, 2H), 4.03 (s, 2H), 3.63 (s,
2H), 2.36 (d, J = 8 Hz, 1H), 2.09 (d, J = 8 Hz, 1H) ppm; 13C NMR
(CDCl3, 100 MHz, 298 K): δ 175.8 (C), 138.4 (C), 137.3 (C), 134.1
(C), 132.5 (C), 132.1 (C), 131.7 (C), 131.4 (CH), 130.7 (C), 130.2
(CH), 129.5 (CH), 128.7 (C), 128.2 (CH), 128.1 (CH), 127.6 (CH),
126.8 (CH), 126.7 (CH), 126.1 (CH), 125.8 (CH), 125.8 (CH), 125.7
(CH), 123.8 (CH), 51.1 (CH2), 48.2 (CH), 45.8 (CH) ppm; MS (FAB):
m/z 592.2 [M + H]+, 100%; 540.4, 48%; HRMS (FAB) calcd for
C43H30O2N: 592.2277; obsd m/z 592.2283 [M + H]+. Anal. Calcd for
C43H29NO2: C, 87.28; H, 4.94; N, 2.37. Found: C, 87.35; H, 4.57; N, 2.29.
N-(1-Anthryl) Succinimide (2a). To a solution of cis-endo-
bicyclo[2.2.1]hept-5-ene-2,3- dicarboxylic anhydride (3)13 (0.136 g,
0.83 mmol) and 1-aminoanthracene (0.160 g, 0.83 mmol) in acetic acid
(6 mL) was added zinc acetate dihydrate (0.018 g, 0.08 mmol). The
reaction mixture was refluxed for 2 h. After cooling, the reaction mixture
was poured into iceÀwater (120 mL) and was extracted with CH2Cl2
(20 mL Â 3). The organic layers were combined and washed with 0.5 M
NaHCO3 aqueous solution (20 mL Â 3), dried over anhydrous
anhydrous MgSO4, filtered, and evaporated into dryness to afford a
dark brown solid. The crude product was further purified by column
chromatography on silica gel (CH2Cl2) giving 1b as a pale brown solid
(0.254 g, 90%): mp 227À228 °C (CHCl3/EtOH); 1H NMR (CD2Cl2,
500 MHz, 253 K): δ 8.54 (s, 1H), 8.13À8.11 (m, 3H), 8.05À7.98 (m,
2H), 7.52À7.48 (m, 3H), 7.13 (d, J = 5 Hz, 1H), 6.39 (s, 2H), 3.71
(s, 2H), 3.55 (s, 2H), 1.82 (d, J = 10 Hz, 1H), 1.71 (d, J = 10 Hz,
1H) ppm; 13C NMR (CDCl3, 100 MHz, 298 K): δ 177.3 (C), 177.0
(C), 136.1 (CH), 134.8 (CH), 132.2 (C), 132.1 (C), 132.0 (C), 131.9
(C), 130.3 (CH), 129.4, 129.0, 128.4 (CH), 128.3 (CH), 128.1 (CH),
127.5, 127.5, 127.4 (CH), 127.2 (CH), 126.3 (CH), 126.0 (CH), 125.9
(CH), 125.8 (CH), 124.4 (CH), 124.3 (CH), 121.8 (CH), 120.7 (CH),
53.0 (CH2), 52.4 (CH2), 47.1 (CH), 46.1 (CH), 45.7 (CH), 45.4 (CH)
ppm; MS (FAB+): m/z 340.1 (M+H+, 90%), 339.1 (M+, 100%), 307.1
(43%); MS (FAB): m/z 340.1 [M + H]+, 90%; 339.1 [M]+, 100%; 307.1,
43%; HRMS (FAB) calcd for C23H17NO2: 339.1259; obsd m/z
339.1259 [M]+. Anal. Calcd for C23H17NO2: C, 81.40; H, 5.05; N,
4.13. Found: C, 81.25; H, 5.06; N 4.05.
N-(2-Anthryl) Succinimide (2b). To a solution of cis-endo-
bicyclo[2.2.1]hept-5-ene-2,3- dicarboxylic anhydride (3)13 (0.136 g,
0.83 mmol) and 2-aminoanthracene (0.160 g, 0.83 mmol) in acetic acid
(6 mL) was added zinc acetate dihydrate (0.018 g, 0.08 mmol). The
reaction mixture was refluxed for 1.5 h. After cooling, the reaction
mixture was poured into iceÀwater (120 mL). The aqueous solution
was extracted with CH2Cl2 (20 mL Â 3), and the organic layers were
combined and washed with 0.5 M NaHCO3 aqueous solution (20 mL Â
3). The organic layer was dried over anhydrous MgSO4, filtered, and
evaporated into dryness to afford a brown solid. The crude product was
further purified by column chromatography on silica gel (CH2Cl2)
giving a pale brown solid of 2b (0.256 g, 91%): mp 218À220 °C
(CH2Cl2/EtOH); 1H NMR (CD2Cl2, 400 MHz, 298 K): δ 8.47 (d, J =
8 Hz, 2H), 8.07À8.03 (m, 3H), 7.81 (s, 1H), 7.52À7.51 (m, 2H), 7.19
(d, J = 8 Hz, 1H), 6.34 (s, 2H), 3.50 (s, 4H), 2.36 (d, J = 8 Hz, 1H), 2.09
(d, J = 8 Hz, 1H) ppm; 13C NMR (CDCl3, 100 MHz, 298 K): δ 176.9
(C), 134.7 (CH), 132.2 (C), 131.9 (C), 130.9 (C), 130.7 (C), 129.4
(CH), 128.8 (C), 128.2 (CH), 128.2 (CH), 126.9 (CH), 126.3 (CH),
125.9 (CH), 125.8 (CH), 125.8 (CH), 123.7 (CH), 52.3 (CH2), 45.9
(CH), 45.6 (CH) ppm; MS (FAB): m/z 339.1 [M]+, 100%; 307.1, 88%;
HRMS (FAB) calcd for C23H17NO2: 339.1259; obsd 339.1264 [M]+.
Anal. Calcd for C23H17NO2: C, 81.40; H, 5.05; N, 4.13. Found: C, 81.12;
H, 5.07; N, 4.19.
with wavelength of 365 nm for 2 h. The reaction gave a brown product
quantitatively, which displayed low solubility in most ordinary NMR
1
solvents: mp 335À337 °C. H NMR (CDCl3, 400 MHz, 25 °C): δ
7.82À7.73 (m, 4H), 7.62À7.31 (m, 24H), 6.86À6.82 (m, 4H),
6.64À6.61 (m, 4H), 6.42 (d, J = 8 Hz, 2H), 6.16 (d, J = 8 Hz, 2H),
4.73 (s, 2H), 3.93À3.86 (m, 6H), 3.47À3.44 (m, 4H), 3.37 (d, J = 12 Hz,
2H), 2.25 (d, J = 12 Hz, 2H), 1.97 (d, J = 12 Hz, 2H) ppm; MS (FAB):
m/z 1183.45 [M + H]+, 100%; HRMS (FAB) calcd for C86H59N2O4:
1183.4469; obsd m/z 1183.4478 [M + H]+.
’ ASSOCIATED CONTENT
S
Supporting Information. The proton and carbon NMR
b
spectra of 1, 2, 6, and 8; protonÀproton COSY spectra of 1a, 2a,
1
and 8; H NMR equilibration spectra of 1a and 2a; variable-
temperature 1H NMR spectra of 1b; the potential energy curves
of the CÀN bond rotational barriers; ORTEP drawings of N-
anthrylsuccinimides; crystal data/structure refinement for 1a, 2b,
2a, and 2b (with cif files); the UV spectra of 1a, 2b, 2a, 2b, and 6;
the table of UV absorption and fluorescence properties; the solid-
1
state absorption and emission spectra of dimer 8; H NMR
spectra of compound 1b and its photoadduct 8. This material is
available free of charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: tcchou@cyut.edu.tw.
’ ACKNOWLEDGMENT
This work was supported by a Theme Project from the
Institute of Chemistry, Academia Sinica, Taiwan.
’ REFERENCES
(1) Rushton, G. T.; Burns, W. G.; Lavin, J. M.; Chong, Y. S.;
Pellechia, P.; Shimizu, K. D. J. Chem. Educ. 2007, 84, 1499–1501.
(2) Chong, Y. S.; Carroll, W. R.; Burns, W. G.; Smith, M. D.;
Shimizu, K. D. Chem.—Eur. J. 2009, 15, 9117–9126.
(3) Tafazzoli, M.; Ziyaei-Halimjani, A.; Ghiasi, M.; Fattahi, M.; Saidi,
M. R. J. Mol. Struct. 2008, 886, 24–31.
(4) Kishikawa, K.; Yoshizaki, K.; Kohmoto, S.; Yamamoto, M.;
Yamaguchi, K.; Yamada, K. J. Chem. Soc., Perkin Trans. 1 1997,
1233–1239.
(5) Marshall, K.; Rosmarion, K.; Sklyut, O.; Azar, N.; Callahan, R.;
Rothchild, R. J. Fluorine Chem. 2004, 125, 1893–1907.
(6) Eto, M.; Setoguchi, K.; Harada, A.; Sugiyam, E.; Harano, K.
Tetrahedron Lett. 1998, 39, 9751–9754.
(7) Yoshitake, Y.; Misaka, J.; Setoguchi, K.; Abe, M.; Kawaji, T.; Eto,
M.; Harano, K. J. Chem. Soc., Perkin Trans. 2 2002, 1611–1619.
(8) Cao, H.; Diaz, D. I.; DiCesare, N.; Lakowicz, J. R.; Heagy, M. D.
Org. Lett. 2002, 4, 1503–1505.
(9) Head, N. J.; Oliver, A. M.; Look, K.; Lokan, N. R.; Jones, G. A.;
Paddon-Row, M. N. Angew. Chem., Int. Ed. 1999, 38, 3219–3222.
(10) Tyson, D. S.; Carbaugh, A. D.; Ilhan, F.; Santos-Pꢀerez, J.;
Meador, M. A. Chem. Mater. 2008, 20, 6595–6596.
(11) Grossmann, G.; Potrzebowski, M. J.; Olejniczak, S.; Ziꢀozkowska,
N. E.; Bujacz, G. D.; Ciesielski, W.; Prezdo, W.; Nazarov, V.; Golovko, V.
New J. Chem. 2003, 27, 1095–1101.
(12) Carroll, W. R.; Pellechia, P.; Shimizu, K. D. Org. Lett. 2008, 10,
3547–3550.
(13) Salvati, M. E.; Balog, A.; Wei, D. D.; Pickering, D.; Attar, R. M.;
Geng, J.; Rizzo, C. A.; Hunt, J. T.; Gottardis, M. M.; Weinmann, R.;
Martinez, R. Bioorg. Med. Chem. Lett. 2005, 15, 389–393.
(14) Chou, T.-C.; Liao, K.-C.; Lin, J.-J. Org. Lett. 2005, 7, 4843–4846.
Photodimerization of 1b, Formation of Dimer (8). The
pulverized crystalline of N-2-anthrylimide 1b was sandwiched in two
glass plates, and then was irradiated in a Rayonet photochemical reactor
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The Journal of Organic Chemistry
NOTE
(15) Chou, T.-C.; Hwa, C.-H.; Lin, J.-J.; Liao, K.-C.; Tseng, J.-C.
J. Org. Chem. 2005, 70, 9717–9726.
(16) Mati, L. K.; Cockroft, S. L. Chem. Soc. Rev. 2010, 39, 4195–4205.
(17) Chein, R.-J.; Corey, E. J. Org. Lett. 2010, 12, 132–135.
(18) Nishio, M. CrystEngComm 2004, 6, 130–158.
(19) Kim, E.-i.; Paliwal, S.; Wilcox, C. S. J. Am. Chem. Soc. 1998,
120, 11192–11193.
(20) Jennings, W. B.; Farrell, B. M.; Malone, J. F. Acc. Chem. Res.
2001, 34, 885–894.
(21) Tsuzuki, S.; Honda, K.; Uchimaru, T.; Mikami, M.; Tanabe, K.
J. Am. Chem. Soc. 2002, 124, 104–112.
(22) Takaguchi, Y.; Tajima, T.; Yanagimoto, Y.; Tsuboi, S.; Ohta, K.;
Motoyoshiya, J.; Aoyama, H. Org. Lett. 2003, 5, 1677–1679.
(23) Ishida, Y.; Kai, Y.; Kato, S.-Y.; Misawa, A.; Amano, S.; Matsuoka,
Y.; Saigo, K. Angew. Chem., Int. Ed. 2008, 47, 8241–8245.
(24) Four configurational isomers, head-to-head (HH) or head-to-
tail (HT) isomers with syn or anti isomerism, are possibly formed from
the photodimerization of 1b. The HH dimers, either syn- or anti-, were
not considered in view of steric hindrance that would impede molecules
of 1b to properly align for effective solid-state photodimerization.
(25) When irradiated at the wavelengths below 270 nm (λex
<
270 nm), all N-anthrylsuccinimides and anhydride 6 exhibited very weak
fluorescence (Φfl < 0.001%).
(26) Langhals, H.; Saulich, S. Chem.—Eur. J. 2002, 8, 5630–5643.
(27) The absorption and emission spectra of N-anthrylsuccinimides
have not shown significant red- or blue-shifts in solvents of different
polarity, indicating the absence of intramolecular charge transfer in these
molecular systems.
(28) At relatively lower concentration (1 Â 10À6 M), the same
activity was also observed, confirming that the fluorescence energy
transfer occurs intramolecularly.
(29) Melinger, J. S.; Pan, Y.; Kleiman, V. D.; Peng, Z.; Davis, B. L.;
McMorrow, D.; Lu, M. J. Am. Chem. Soc. 2002, 124, 12002–12012.
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