Solid-state fluorescence of 6-aryl-9-(dibutylamino)benzo[a]phenoxazin-5- ones

Article abstract of DOI:10.1016/j.tet.2013.02.083

6-(9-Anthryl)- and 6-(1-naphthyl)-9-(dibutylamino)benzo[a]phenoxazin-5-ones exhibited fluorescence maximum at around 700 nm in the crystalline form. Their fluorescence quantum yields were significantly higher than that of previously reported 6-perfluoro[4-methyl-3-(1-methylethyl)pent-2-en-2-oxy] derivative due to the isolated dimer-type packing.

Full text of DOI:10.1016/j.tet.2013.02.083

Tetrahedron 69 (2013) 3410e3414
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Solid-state fluorescence of 6-aryl-9-(dibutylamino)benzo[a]
phenoxazin-5-ones
*
Masaki Matsui , Yukiyo Ando, Osamu Tokura, Yasuhiro Kubota, Kazumasa Funabiki
Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 15 January 2013
Received in revised form 18 February 2013
Accepted 22 February 2013
Available online 26 February 2013
6-(9-Anthryl)- and 6-(1-naphthyl)-9-(dibutylamino)benzo[a]phenoxazin-5-ones exhibited fluorescence
maximum at around 700 nm in the crystalline form. Their fluorescence quantum yields were signifi-
cantly higher than that of previously reported 6-perfluoro[4-methyl-3-(1-methylethyl)pent-2-en-2-oxy]
derivative due to the isolated dimer-type packing.
Ó 2013 Elsevier Ltd. All rights reserved.
Keywords:
Solid state
Naphthooxazine dyes
Single X-ray crystallography
Fluorescence
Near-infrared solid-state fluorescence
1. Introduction
improved. We report herein the effect of an aryl group at the
6-position on the solid-state florescence intensity of 9-(dibutyla-
Survey of solid-state fluorescent organic compounds is one of
the most exciting subjects in connection with emitters in organic
electroluminescence (EL) device,1 solid-state dye laser,2 and
probes.3 Especially, as near-infrared fluorescence can improve
photon penetration through tissue, organic fluorophores have been
used as in vivo imaging materials.4 As fluorescence intensity in the
solid state is usually reduced due to the wide aromatic moiety of the
fluorophores, the introduction of bulky substituent(s) into the flu-
mino)benzo[a]phenoxazin-5-ones.
2. Results and discussion
2.1. Synthesis
Nile Red-Bu (5a) and 6-perfluoro[4-methyl-3-(1-methylethyl)
pent-2-en-2-oxy] derivative 5b were prepared as described in
our previous paper.7 6-Aryl-9-(dibutylamino)benzo[a]phenoxazin-
5-ones 5ce5f were prepared as shown in Scheme 1. 5-Dibutylamino-
2-nitrosophenol hydrochloride salt (1) was allowed to react with
2-bromo-1-naphthol (2) to give 6-bromo-9-(dibutylamino)benzo[a]
orophores can inhibit the
Nile Red, used as a hydrophobic probe5 and a pH sensor,6 is a
strongly fluorescent compound in solution and has a wide -elec-
p/p-interactions to improve the intensity.
p
tron system. Recently, Nile Red derivatives have been proposed as
red emitters in EL devices.7 In our previous paper, 9-dibutylamino-
6-perfluoro[4-methyl-3-(1-methylethyl)pent-2-en-2-oxy]benzo[a]
phenoxazin-5-one has been reported to show the fluorescence
maximum (Fmax) at 717 nm with a fluorescence quantum yield (Ff
)
0.02 in a powder form.8 As there are few neutral compounds, which
exhibit Fmax beyond 700 nm in the solid state, 9-(dialkylamino)
benzo[a]phenoxazin-5-ones are interesting fluorophores. We con-
sidered that the Ff of this derivative in the solid state is low com-
pared to that in solution due to 24 CH/F and
p/p-interactions.
Therefore, when a bulky aryl group is introduced into the fluo-
rophore, the solid-state fluorescence quantum yield could be
Scheme 1. Reagents and conditions: (i) 1 (10 mmol), 2 (10 mmol), DMF (60 mL), reflux,
4 h; (ii) 3 (1.0 mmol), 4 (2.0 mmol), Pd2(dba)3 (4 mol %), SPhos (8 mol %), aq 2 M
Na2CO3 (10 mL, 20 mmol), EtOH/toluene (1/4) (26 mL), 100 ꢀC, 15 h.
* Corresponding author. E-mail address: matsuim@gifu-u.ac.jp (M. Matsui).
0040-4020/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2013.02.083

M. Matsui et al. / Tetrahedron 69 (2013) 3410e3414
3411
phenoxazin-5-one (3), followed by the reaction with arylboronic
acids 4ce4f to give 5ce5f.
2.2. UVevis absorption and fluorescence spectra
Fig. S1 in Supplementary data depicts the UVevis absorption
and fluorescence spectra of 5e in various solvents. Compound 5e
exhibited the most intense fluorescence in dichloromethane.
Therefore, those of the other derivatives were measured in
dichloromethane. Fig. 1 shows the UVevis absorption and fluo-
rescence spectra of 5ae5f in dichloromethane. The results are also
summarized in Table 1. These compounds showed the UVevis ab-
sorption maximum (lmax) in the range of 543e577 nm. The lmax of
5b was most bathochromic among 5ae5f due to the electron-
withdrawing nature of a perfluoroalkenyloxy group at the 6-
position. The Fmax was observed in the range of 609e634 nm, the
500
400
300
200
100
5b
5c
5d
5e
Stokes shift being 54e83 nm. The Ff and fluorescence lifetime (sf
)
0
values of 5a (Ff: 0.85, f: 4.6), 5b (0.79, 4.4), 5c (0.54, 3.5), 5d (0.69,
s
500
600
700
800
4.2) were greater than those of 5e (0.20, 1.8) and 5f (0.14, 1.2).
This comes from the faster non-radiative rate constants (knr) of 5e
and 5f rather than their slow radiative rate constant (kf) in
dichloromethane.
Wavelength / nm
Fig. 2. Solid-state fluorescence spectra of 5ce5e.
at 711 nm.7 This compound showed Ff (0.02) with Fmax at 732 nm in
the crystalline form recrystallized from hexane. Thus, we could find
that new compounds 5c, 5d, and 5e exhibit larger Ff than known 5b.
0.8
0.6
0.4
0.2
0
80
60
40
20
0
5a
5b
5c
5d
5e
5f
The sf of 5 was not measured due to low Ff in the solid state.
2.3. Single X-ray crystallography
To understand why the Ff value of these compounds in the
solid state changes depending on the substituent at the 6-position,
the single X-ray crystallography of 5a, 5b, 5c, 5d, and 5e was
performed. Fig. 3 shows the single X-ray crystallography of
6-unsubstituted derivative 5a. Molecules are packed in a herring-
bone fashion (overview). Molecules A and B are arranged in par-
-interactions, there being the interplanar distance
3.34 A (top view and side view). The same results are observed
between B and C. Thus, compound 5a has strong consecutive p/p-
500
600
700
800
900
Wavelength / nm
allel with
p
/p
ꢀ
Fig. 1. UVevis absorption and fluorescence spectra of 5ae5f in dichloromethane.
Measured on 1ꢁ10ꢂ5 mol dmꢂ3 of substrate at 25 ꢀC.
interactions.
Table 1
UVevis absorption and fluorescence spectra of 5ae5f
Compd In dichloromethanea
Solid state
lex Fmax
c
lmax )/nm lex Fmax
(
3
/
/
Ff
sf/
kfb
/
knr
/
/
/
Ff
nm nm
ns 109 sꢂ1 109 sꢂ1 nm nm
5a
5b
5c
5d
5e
5f
543 (60,600) 540 609 0.85 4.6 0.19
577 (59,700) 577 631 0.79 4.4 0.18
549 (45,700) 552 625 0.54 3.5 0.15
552 (48,600) 549 620 0.69 4.2 0.16
555 (48,500) 556 619 0.20 1.8 0.11
551 (38,200) 553 634 0.14 1.2 0.12
0.03
0.05
0.13
0.07
0.45
0.71
dd dd
dd
690 732 0.02
631 686 0.03
654 711 0.04
635 694 0.04
dd dd
dd
Measured on 1.0ꢁ10ꢂ5 mol dmꢂ3 of substrate at 25 ꢀC.
a
b
c
Radiative rate constant (kf¼Ff/sf).
Non-radiative rate constant (knr¼(1ꢂFf)/
sf).
d
Too weak to be measured.
Fig. 3. Single X-ray crystallography of 5a.
The fluorescence spectra of 5ae5f in the crystalline form
recrystallized from hexane are indicated in Fig. 2.9 The results are
also listed in Table 1. They showed Fmax in the range of 686e711 nm.
The Fmax is more bathochromic than that in dichloromethane
(609e634 nm) due to the intermolecular interactions in the solid
state. Though the Ff in the solid state was extremely low compared
with those in dichloromethane, the Ff in the solid state was sig-
nificantly more intense in the order of the compounds: 5d (0.04), 5e
(0.04)>5c (0.03), 5b (0.02)>5f (0.00), 5a (0.00). In the series of solid-
state fluorescence of naphthooxazine dyes, compound 5b has been
reported to show the largest Ff (0.02) in the powder form with Fmax
The single X-ray crystallography of 5b is depicted in Fig. 4.
Molecules form a pair of head-to-tail dimers (overview (1)). A
molecule has 24 CH/F interactions with adjacent molecules (over-
view (2)). Molecules A and B are arranged in parallel by
p
/
p
-in-
teractions with interplanar distance 3.52 A (top view (2) and side
view (2)). No -interactions are observed between B and C (top
view (3)). Molecule B also has small -interactions with D at the
edge of naphthooxazine ring (top view (4) and side view (2)). Thus,
5b has loosely consecutive -stacking and 24 CH/F interactions.
ꢀ
p/p
p/p
p/p

3412
M. Matsui et al. / Tetrahedron 69 (2013) 3410e3414
Fig. 4. Single X-ray crystallography of 5b.
The single X-ray crystallography of 5c is indicated in Fig. 5.
Molecules are packed in a herring-bone fashion (overview). Mole-
cules A and B are arranged in parallel with p/p-interactions, there
ꢀ
being the interplanar distance 3.54 A (top view and side view). The
Fig. 6. Single X-ray crystallography of 5d.
same results are observed between B and C. Thus, compound 5c has
consecutive
p/p-interactions (side view). The dihedral angle be-
interplanar distance is too long to have
p
/
p
-interactions, there
being, 5.04 and 7.20 A, respectively (side view (1)). Thus,1-naphthyl
group is sufficiently bulky to inhibit consecutive -stacking.
Molecule E is also packed in parallel for B. -interactions are
ꢀ
tween the phenyl ring at the 6-position and naphthooxazine fluo-
rophore is 66.9ꢀ (side view). Thus, though the phenyl ring is not
p/p
bulky enough to prevent the
p/p-interactions between the naph-
p/p
thooxazine fluorophores, the interplanar distance between A and B
observed between the naphthyl groups (top view (4) and side view
(2)). Thus, 5d has isolated dimer-type packing.
ꢀ
ꢀ
in 5c (3.54 A) is significantly longer than that in 5a (3.34 A).
The single X-ray crystallography of 5e is shown in Fig. 7. Mole-
cules form a pair of head-to-tail dimer and are packed in parallel
(overview). Molecule A has p/p-interactions for B with interplanar
ꢀ
distance 3.87 A (top view (2) and side view (1)). This interplanar
ꢀ
distance is longer than that of 5d (3.59 A). Though molecule C is
arranged in parallel for B, no
p/p-interactions are observed (top
view (3)). The dihedral angle between the anthryl group at the 6-
position and naphthooxazine fluorophore is 95.3ꢀ (side view (1)).
Molecule E is also packed in parallel for B (side view (1)).
p/p-In-
teractions are observed between the anthryl groups with inter-
ꢀ
planar distance 3.42 A (top view (4) and side view (2)). Thus, 5e has
isolated dimer-type packing.
Compounds 5a and 5c have similar consecutive p/p-stacking. As
ꢀ
the intermolecular distance between a pair of dimers in 5c (3.54 A)
ꢀ
is slightly longer than that of 5a (3.34 A), 5c could exhibit solid-
state fluorescence. Compound 5b has loosely consecutive
p/p-
stacking and 24 CH/F interactions to exhibit weak fluorescence in
the solid state. Compounds 5d and 5e have similar isolated dimer-
type packing. The Fmax of 5e and 5d in dichloromethane was ob-
served at 619 and 620 nm, respectively, there being no remarkable
differences. Those of 5e and 5d in the crystalline form were ob-
served at 694 and 711 nm, respectively. Thus, the Fmax of 5e is
significantly hypsochromic compared with 5d. The Ff of 5d and 5e
in solution is 0.69 and 0.20, respectively. Those in the solid state are
0.04 and 0.04, respectively. Therefore, the reduction ratio of Ff of 5e
in the crystalline form (0.04/0.20) is less than that of 5d (0.04/0.69).
Fig. 5. Single X-ray crystallography of 5c.
Fig. 6 indicates the single X-ray crystallography of 5d. Molecules
form a pair of head-to-tail dimer and are packed in parallel (over-
view). Molecule A has
p/p-interactions with B, there being the
ꢀ
interplanar distance 3.59 A (top view (2) and side view (1)). The
dihedral angle between the naphthyl ring and naphthooxazine
fluorophore is 89.3ꢀ (side view (1)). Though, for molecule B, the
neighboring molecules C and D are also packed in parallel, the

M. Matsui et al. / Tetrahedron 69 (2013) 3410e3414
3413
were measured by Hamamatsu Photonics Quataurus-QY and Quan-
taurus- , respectively.
s
4.2. Materials
3-(Dibutylamino)phenol (1), 1-naphthaleneboronic acid (4d),
9-anthraceneboronic acid (4e), tetrakis(triphenylphpophine), and
palladium(0) (Pd(PPh3)4) were purchased from TOKYO CHEMICAL
INDUSTRY CO., LTD. Phenylboronic acid (4c) and 2-dicyclohexyl-
phosphyno-20,60-dimethoxybiphenyl (SPhos) were obtained from
SigmaeAldrich. Tris(dibenzylidene acetone)diparadium (Pd2(dba)3)
was supplied from KANTO CHEMICAL CO., INC. 2-Bromo-1-naphthol
(2)10 and 9,9-dibutylfluoreneboronic pinacol ester (4f)11 were
prepared as described in the literature. 9-Dibuthylamino-5H-
benzo[a]phenoxazine-5-one (5a) and 9-dibuthylamino-6-perfluoro
(4-methyl-3-(1-methylethyl)pent-2-en-2-oxy)-5H-benzo[a]phenox-
azine-5-one (5b) were prepared as described in our previous paper.8
4.3. Synthesis of 6-bromo-9-dibuthylamino-5H-benzo[a]
phenoxazine-5-one (3)
To a DMF solution (60 mL) of 2-bromo-1-naphthol (2, 2.231 g,
10 mmol) was added 5-dibutylamino-2-nitrosophenol hydrochloric
acid (1, 2.688 g, 10 mmol). The mixture was refluxed for 4 h. After the
reaction was completed, the solvent was removed in vacuo. The
product was isolated by column chromatography (SiO2, CH2Cl2/
AcOEt (v/v¼40:1)). Yield 1.36 g (30%); mp 185e187 ꢀC; 1H NMR
(CDCl3)
d
¼1.00 (t, J¼7.3 Hz, 6H), 1.42 (sex, J¼7.3 Hz, 4H), 1.66 (quin,
J¼7.3 Hz, 4H), 3.41 (t, J¼7.3 Hz, 4H), 6.58 (d, J¼2.7 Hz, 1H), 6.70 (dd,
J¼9.1 and 2.7 Hz,1H), 7.64 (d, J¼9.1 Hz,1H), 7.66 (t, J¼7.3 Hz,1H), 7.73
(t, J¼7.3 Hz, 1H), 8.38 (d, J¼7.3 Hz, 1H), 8.67 (d, J¼7.3 Hz, 1H); 13C
NMR (CDCl3)
d¼13.94, 20.29, 29.42, 51.28, 96.58, 110.56, 112.04,
123.87, 124.72, 126.30, 130.04, 130.82, 130.98, 131.08, 131.59, 138.36,
146.48,147.58,151.46,177.19. Anal. Found: C, 63.55; H, 5.37; N, 6.22%.
Calcd for C24H25BrN2O2: C, 63.58; H, 5.56; N, 6.18%.
Fig. 7. Single X-ray crystallography of 5e.
4.4. Synthesis of 6-aryl-9-dibutylamino-5H-benzo[a]phenox-
azine-5-ones 5
These results could come from longer interplanar distance of 5e
ꢀ
ꢀ
(3.87 A) than that of 5d (3.59 A). Though 5c, 5d, and 5e could show
significantly larger Ff than previously reported 5b in the solid state,
the Ff is still low, there being 0.030.04. As the naphthooxazine ring
To ethanol/toluene (1:4) mixed solvent (25 mL) were added
6-bromo-9-dibutylamino-5H-benzo[a]phenoxazine-5-one (3, 453mg,
1.0 mmol), an arylboronic acid (4, 2.0 mmol), tri(dibenzylideneacetone)
dipalladium (Pd2(dba)3, 37 mg, 4 mol %), dicyclohexylphosphino-20,60-
dimethoxybiphenyl (SPhos, 33 mg, 8 mol %), and aqueous 2 M sodium
carbonate (10 mL). The mixture was heated at 100 ꢀC for 15 h. After the
reaction was completed, the mixture was filtered. The filtrate was
poured into water. The product was extracted with ethyl acetate
(50 mLꢁ3), dried over anhydrous sodium sulfate, and purified by col-
umn chromatography (SiO2, toluene/ethyl acetate¼20:1).
is a widely planar
p-plane, p/p-interactions are easily produced.
Even bulky 6-(9-anthryl) derivative 5e has isolated dimer-type
packing. No emission from the eximer was observed. Therefore,
to produce more intensely fluorescent naphthooxazine dyes in the
solid state, it is essential to make a molecular design to form iso-
lated monomer type packing.
3. Conclusions
9-Dibutylamino-6-(1-naphthyl)- and -6-(9-anthryl)benzo[a]
phenoxazin-5-ones showed Fmax at around 700 nm in the crystal-
line form. The fluorescence of these compounds was more intense
than previously reported 6-perfluoro(4-methyl-3-(1-methylethyl)
pent-2-en-2-oxy) derivative due to the isolated dimer-type packing.
4.4.1. 9-Dibutylamino-6-phenyl-5H-benzo[a]phenoxazine-5-one
(5c). Yield 356 mg (79%); mp 207e208 ꢀC; 1H NMR (CDCl3)
d¼0.96
(t, J¼7.6 Hz, 6H), 1.36 (sex, J¼7.6 Hz, 4H), 1.59 (quin, J¼7.6 Hz, 4H),
3.33 (t, J¼7.6 Hz, 4H), 6.28 (d, J¼2.7 Hz, 1H), 6.63 (dd, J¼8.9 and
2.7 Hz, 1H), 7.39 (t, J¼7.4 Hz, 1H), 7.49 (t, J¼7.4 Hz, 2H), 7.56
(d, J¼7.4 Hz, 2H), 7.60 (d, J¼8.9 Hz, 1H), 7.65 (t, J¼7.6 Hz, 1H), 7.73
(t, J¼7.6 Hz, 1H), 8.37 (d, J¼7.6 Hz, 1H), 8.70 (d, J¼7.6 Hz, 1H); 13C
4. Experimental
4.1. Instruments
NMR (CDCl3)
d
¼13.89 (2C), 20.20 (2C), 29.38 (2C), 51.13 (2C), 96.25,
111.01, 115.43, 119.58, 120.11, 120.63, 123.61, 125.65, 126.31, 129.71,
129.87 (2C), 131.08, 131.59, 132.15 (2C), 138.46, 146.69, 149.18,
Melting points were measured with a Yanaco MP-13 micro-
melting-point apparatus. NMR spectra were obtained by a JEOL ECX
400P spectrometer. Elemental analysis was performed with a Yanaco
MT-6 CHN corder. UVevis absorption and fluorescence spectra were
taken on Hitachi U-4100 and JASCO FP-8600 instruments, re-
spectively. The fluorescence quantum yield and fluorescence lifetime
151.69, 155.52, 183.53; IR (NaCl) n
1585 cmꢂ1; EIMS (70 eV) m/z
(rel intensity) 450 (Mþ, 64), 403 (100). Anal. Found: C, 79.75; H,
6.85; N, 6.25%. Calcd for C30H30N2O2: C, 79.97; H, 6.71; N, 6.22%.
4.4.2. 9-Dibutylamino-6-(1-naphthyl)-5H-benzo[a]phenoxazine-5-
one (5d). Yield 425 mg (85%); mp 172e174 ꢀC; 1H NMR (CDCl3)

3414
M. Matsui et al. / Tetrahedron 69 (2013) 3410e3414
d
¼0.90 (t, J¼7.3 Hz, 6H),1.28 (sex, J¼7.3 Hz, 4H),1.51 (quin, J¼7.3 Hz,
squares calculations. Crystal data for 5c: C30H30N2O2, Mw¼450.56,
ꢀ
4H), 3.24 (t, J¼7.3 Hz, 4H), 6.01 (d, J¼2.8 Hz, 1H), 6.60 (dd, J¼9.2 and
2.8 Hz, 1H), 7.36 (t, J¼6.9 Hz, 1H), 7.46 (t, J¼6.9 Hz, 1H), 7.52
(d, J¼6.9 Hz, 1H), 7.60e7.70 (m, 4H), 7.77 (t, J¼7.5 Hz, 1H), 7.94 (t,
J¼6.9 Hz, 2H), 8.38 (d, J¼7.5 Hz, 1H), 8.77 (d, J¼7.5 Hz, 1H); 13C NMR
monoclinic, P21/c, Z¼4, a¼5.529(3), b¼19.961(10), c¼21.576(11) A,
b
¼91.390(8)ꢀ, Dcalcd¼1.257 g cmꢂ3, T¼293(2) K, 18,589 reflections
were collected, 5369 unique (Rint¼0.0546), 309 parameters,
R1¼0.1049, wR2¼0.2521, GOF¼1.065, refinement on F2. Crystal data
(CDCl3)
d¼13.85 (2C), 20.13 (2C), 29.29 (2C), 50.91 (2C), 96.59,
for 5d: C34H32N2O2, Mw¼500.62, triclinic, P-1, Z¼2, a¼10.200(15),
¼72.63(5)ꢀ,
b
¼89.13(5)ꢀ,
ꢀ
109.84, 116.67, 123.61, 124.77, 125.55, 125.58, 125.85, 125.91, 126.32,
128.21, 128.32, 128.70, 129.89, 130.39, 130.76, 131.34, 131.52, 131.96,
b¼11.266(14), c¼13.055(18) A,
a
g
¼70.92(3)ꢀ, Dcalcd¼1.234 g cmꢂ3, T¼293(2) K, 13,939 reflections
132.26, 133.80, 139.42, 146.83, 148.79, 150.97, 182.12; IR (NaCl)
n
were collected, 6126 unique (Rint¼0.0541), 345 parameters,
1586 cmꢂ1; EIMS (70 eV) m/z (rel intensity) 500 (Mþ, 100), 457 (51);
Anal. Found: C, 81.29; H, 6.57; N, 5.52%. Calcd for C34H32N2O2: C,
81.57; H, 6.44; N, 5.60%.
R1¼0.1175, wR2¼0.3051, GOF¼0.986, refinement on F2. Crystal data
for 5e: C38H34N2O2, Mw¼550.67, triclinic, P-1, Z¼2, a¼9.236(14),
ꢀ
b¼12.342(19), c¼13.037(18) A,
a
¼86.07(4)ꢀ,
b
¼79.81(3)ꢀ,
g
¼88.74(3)ꢀ, Dcalcd¼1.253 g cmꢂ3, T¼293(2)ꢀK, 15,121 reflections
4.4.3. 6-(9-Anthryl)-9-dibutylamino-5H-benzo[a]phenoxazine-5-one
were collected, 6622 unique (Rint¼0.0986), 381 parameters,
R1¼0.0835, wR2¼0.1922, GOF¼1.016, refinement on F2.
Crystallographic data have been deposited with Cambridge
Crystallographic Data Centre (5c: CCDC895518, 5d: CCDC895516,
and 5e: CCDC895517).
(5e). Yield 171 mg (31%); mp 296e298 ꢀC; 1H NMR (CDCl3)
d¼0.85
(t, J¼7.8 Hz, 6H), 1.24 (sex, J¼7.8 Hz, 4H), 1.44 (quin, J¼7.8 Hz, 4H),
3.17 (t, J¼7.8 Hz, 4H), 5.84 (d, J¼2.8 Hz, 1H), 6.59 (dd, J¼9.2 and
2.8 Hz, 1H), 7.34 (t, J¼7.6 Hz, 2H), 7.45 (t, J¼7.6 Hz, 2H), 7.63
(d, J¼9.2 Hz, 1H), 7.71 (t, J¼7.8 Hz, 1H), 7.80e7.84 (m, 3H), 8.08
(d, J¼7.6 Hz, 2H), 8.39 (d, J¼7.8 Hz, 1H), 8.58 (s, 1H), 8.85 (d,
Supplementary data
J¼7.8 Hz, 1H); 13C NMR (CDCl3)
¼13.81 (2C), 20.09 (2C), 29.25 (2C),
d
50.83 (2C), 96.72, 109.91, 114.77, 123.73, 124.87, 125.07 (2C), 125.66
(2C), 126.24 (2C), 126.50, 127.32, 127.63, 128.68 (2C), 130.01, 130.60
(2C), 130.82, 131.49, 131.63, 131.77 (2C), 132.25, 139.31, 147.06,
These date include single X-ray crystallographic data for 5c, 5d,
and 5e. Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.tet.2013.02.083.
149.68, 151.01, 182.13; IR (KBr)
n
1585 cmꢂ1; EIMS (70 eV) m/z (rel
intensity) 550 (Mþ, 100), 507 (38), 465 (28). Anal. Found: C, 82.59;
H, 6.10; N, 5.01%. Calcd for C38H34N2O2: C, 82.88; H, 6.22; N, 5.09%.
References and notes
1. (a) Peng, X. Chem. Mater. 2011, 23, 621e630; (b) Liu, Y.; Tao, X.; Wang, F.; Dang, X.;
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Zhao, Z.; Lam, J. W. Y.; Liu, J.; Chen, S.; Lu, P.; Mahtab, F.; Chen, X.; Sung, H. H. Y.;
Kwok, H. S.; Ma, Y.; Williams, I. D.; Wong, K. S.; Tang, B. Z. Adv. Funct. Mater. 2012,
22, 378e389.
2. Garcia-Moreno, I.; Costela, A.; Martin, V.; Pintado-Sierra, M.; Sastre, R. Adv.
Funct. Mater. 2009, 19, 2547e2552.
3. For example, Haugland, R. Handbook of Fluorescent Probes and Research Chem-
icals, 8th ed.; Molecular Probes: Eugene, OR, 2001.
4. (a) Pu, K.-Y.; Li, K.; Liu, B. Adv. Funct. Mater. 2010, 20, 2770e2777; (b) Li, C.; Xia, J.;
Wei, X.; Yan, H.; Si, Z.; Ju, S. Adv. Funct. Mater. 2010, 20, 2222e2230; (c) Hilder-
brand, S. A.; Weissleder, R. Curr. Opin. Chem. Biol. 2010, 14, 71e79; (d) Frangioni, J.
V. Curr. Opin. Chem. Biol. 2003, 7, 626e634.
4.4.4. 9-Dibutylamino-6-[2-(9,9-dibutylfluorenyl)]-5H-benzo[a]phe-
noxazine-5-one (5f). Yield 26 mg (4%); mp 151e153 ꢀC; 1H NMR
(CDCl3)
d
¼0.70 (t, J¼7.5 Hz, 6H), 0.84e0.96 (m, 10H), 1.11 (quin,
J¼7.5 Hz, 4H), 1.34 (sex, J¼7.5 Hz, 4H), 1.58 (quin, J¼7.5 Hz, 4H), 2.01
(t, J¼7.5 Hz, 4H), 3.30 (t, J¼7.5 Hz, 4H), 6.27 (d, J¼2.8 Hz, 1H), 6.64
(dd, J¼9.2 and 2.8 Hz, 1H), 7.30e7.39 (m, 3H), 7.56e7.69 (m, 4H),
7.73e7.78 (m, 2H), 7.83 (d, J¼8.2 Hz, 1H), 8.40 (d, J¼6.9 Hz, 1H), 8.72
(d, J¼6.9 Hz, 1H); 13C NMR (CDCl3)
¼13.94 (2C), 20.24 (2C), 23.25
d
(2C), 29.50 (2C), 26.17(2C), 29.70, 39.98 (2C), 50.45 (2C), 54.97 (2C),
96.45, 109.91, 118.25, 119.01, 119.68, 123.03, 123.57, 124.90, 125.46,
126.27, 126.72, 126.85, 129.74, 129.93, 130.58, 130.70 (2C), 131.28,
131.57, 131.75, 140.01, 140.25, 141.16, 146.81, 147.71, 149.95, 151.07,
5. (a) Kucherak, O. A.; Oncul, S.; Darwich, Z.; Yuschenko, D. A.; Arntz, Y.; Didier, P.;
ꢁ
Mely, Y.; Klymchenko, A. S. J. Am. Chem. Soc. 2010, 132, 4907e4916; (b) Lampe,
J. N.; Fernandez, C.; Nath, A.; Atkins, W. M. Biochemistry 2008, 47, 509e516.
6. (a) Peng, H.-S.; Stolwijk, J. A.; Sun, L.-N.; Wegener, J.; Wolfbeis, O. S. Angew.
Chem., Int. Ed. 2010, 49, 4246e4249; (b) Polverini, E.; Cugini, G.; Annoni, F.;
Abbruzzetti, S.; Viappiani, C.; Gensch, T. Biochemistry 2006, 45, 5111e5121.
7. Nakaya, T.; Tajima, A.; Saikawa, T. WO2007046247.
151.18, 182.12; IR (NaCl) n
1585 cmꢂ1; FABMS (NBA) m/z 651 (MHþ).
Anal. Found: C, 82.71; H, 8.03; N, 4.17%. Calcd for C45H50N2O2: C,
83.04; H, 7.74; N, 4.30%.
8. Park, S.-Y.; Kubota, Y.; Funabiki, K.; Matsui, M. Tetrahedron Lett. 2009, 50,
1131e1135.
4.5. Single X-ray crystallography of 5
9. The solid-state fluorescence was measured by a JASCO FP-8600 spectropho-
tometer. About 3 mg of sample was put on the cell. The solid-state fluorescence
was checked by irradiating 500 nm light to obtain Fmax. On the basis of the
measured Fmax, the exact excitation wavelength (lex) was obtained. Finally, the
solid-state fluorescence was obtained by irradiating the lex light. Both the slit
width of excitation and fluorescence sides were 5 nm. The sensitivity was low.
To check the reproducibility, the measurement was done four times.
10. Huang, W.-G.; Jiang, Y.-Y.; Li, Q.; Li, J.; Li, J.-Y.; Lu, W.; Cai, J.-C. Tetrahedron 2005,
61, 1863e1870.
The single X-ray crystallography of 5a and 5b has been reported
in our previous paper (5a: CCDC 705404, 5b: CCDC 704026).7 Single
crystals of 5c, 5d, and 5e were obtained by diffusion method using
dichloromethane/hexane mixed solvent. The diffraction data were
collected by an XtaLAB mini diffractometer using graphite mono-
ꢀ
chromated Mo K
a
radiation (
l
¼0.71075 A). The structure was
11. Fomiya, M.; Bradforth, S. E.; Hogen-Esch, T. E. Macromolecules 2009, 42,
6440e6447.
solved by direct methods SIR97 and refined by fill-matrix least-