Naphthotriazole derivatives: Synthesis and fluorescence properties

Article abstract of DOI:10.1016/j.dyepig.2010.03.025

Eight fluorescent compounds containing a naphthotriazole moiety substituted at position 2 by a (vinylsulfonyl)aryl group or its precursors, containing either a hydroxyl or sulphonic acid groups or N-methylglycine, were prepared and characterized. The products were recovered in moderate yield after column chromatography or recrystallization and identified using ¹H and ¹³C NMR; double resonance, heteronuclear multiple quantum coherence and heteronuclear multiple bond correlation experiments were carried out for complete assignment of proton and carbon signals. Absorption and emission spectra were obtained, in acetonitrile and fluorescence quantum yield determined. All compounds offer promise as fluorescent probes owing to their high fluorescence quantum yield.

Full text of DOI:10.1016/j.dyepig.2010.03.025

Dyes and Pigments 87 (2010) 188e193
Contents lists available at ScienceDirect
Dyes and Pigments
journal homepage: www.elsevier.com/locate/dyepig
Naphthotriazole derivatives: Synthesis and fluorescence properties
,
a
a
a
Ana M.F. Oliveira-Campos a , Lígia M. Rodrigues , Ana P. Esteves , Marília E. Silva ,
*
Aravind Sivasubramanian a, Radim Hrdina b, Graça M.B. Soares c,
Tiago A.D. Pinto a b, Oldrich Machalicky b
,
a Centro de Química, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
b Faculty of Chemical Technology, University of Pardubice, Pardubice-Polabiny, Czech Republic
c Departamento de Engenharia Têxtil, Universidade do Minho, Braga, Portugal
a r t i c l e i n f o
a b s t r a c t
Article history:
Eight fluorescent compounds containing a naphthotriazole moiety substituted at position 2 by a (vinyl-
sulfonyl)aryl group or its precursors, containing either a hydroxyl or sulphonic acid groups or N-meth-
ylglycine, were prepared and characterized. The products were recovered in moderate yield after column
chromatography or recrystallization and identified using 1H and 13C NMR; double resonance, hetero-
nuclear multiple quantum coherence and heteronuclear multiple bond correlation experiments were
carried out for complete assignment of proton and carbon signals. Absorption and emission spectra were
obtained, in acetonitrile and fluorescence quantum yield determined. All compounds offer promise as
fluorescent probes owing to their high fluorescence quantum yield.
Received 20 November 2009
Received in revised form
15 March 2010
Accepted 23 March 2010
Available online 9 April 2010
Keywords:
Nitrogen heterocycles
Naphthotriazole
Ó 2010 Elsevier Ltd. All rights reserved.
Vinylsulfone
Azo coupling
Fluorescence spectra
Quantum yield of fluorescence
1. Introduction
2-sulfatoethyl sulfones) so as to prolong storage life and are con-
verted to the corresponding, reactive vinylsulfone derivative in situ in
Compounds containing the 1,2,3-triazole unit have attracted
attention as intermediates for the synthesis of several products such
as dyes [1] or optical brighteners [2]. In particular, naphthotriazoles
exhibit intense fluorescence in the near UV and visible regions and
their high fluorescence quantum yield (>50%, [3]), is comparable to
that of highly fluorescent compounds such as 1-aminonaphthalene
or 9,10-diphenylanthracene, which have quantumyields of qF ¼ 39%
and qF ¼ 98%, respectively [4]. Thus, naphthotriazoles are used as
whitening agents [5] and/or as fluorescent probes [3]; sulfonated
derivatives of 2H-naphthotriazoles are well-known in the textile
industry [6].
Compounds and dyes containing vinylsulfonyl groups or their
precursors display a marked ability to react with nucleophiles, such
as those present in cellulose [7,8], nylon [9] wool [10,11] and other
biomolecules [12]. The present research group recently described
Michael reactions of vinyl sulfone derivatives and Amberlyst-15 as
catalyst [13]. In general, dyes which carry a vinylsulfone group are
commonly produced commercially in a protected form (e.g. as
the dye bath. A water soluble secondary amine such as N-methyl-
taurine can be used to protect the vinylsulfone group [14]; N-meth-
ylglycine (sarcosine), an amino acid containing a secondary amino
group, was also developed for this purpose [15], the mechanism of
dyeing [16,17] involving the release of the reactive vinyl form from
the sulfate derivative under appropriate pH conditions [15].
This paper concerns the syntheses of novel 1,2,3-triazole
derivatives containing reactive vinyl groups as potential markers
for biomolecules and an evaluation of their fluorescence properties.
2. Results and discussion
2.1. Synthesis
The compounds described contain a naphthotriazole moiety
and various substituents at the 2 position of the triazole ring
(Fig. 1), which was obtained in low overall yield by diazotization of
an aniline derivative [18] and azo coupling of the diazonium salt
with an aminonaphthalene derivative followed by oxidation with
copper acetate in DMF or similar, polar solvent at high temperature
(Scheme 1) [6].
* Corresponding author. Tel.: þ351 253 604 377; fax: þ351 253 604 382.
E-mail address: amcampos@quimica.uminho.pt (A.M.F. Oliveira-Campos).
0143-7208/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.dyepig.2010.03.025

A.M.F. Oliveira-Campos et al. / Dyes and Pigments 87 (2010) 188e193
189
8
3'
9b
3a
O
S
O
S
O
S
6
N
N
N
N
N
N
9a
5a
O
O
O
N
N
N
1'
R
4
O
OH
1
2a: R = H
3
HO
O
S
O
2b: R = SO3H
N
N
N
N
N
N
1'
3'
S
O
N
N
NH2
OH
OH
S
S
O
O
O
O
O
4
6
5
O
S
N
N
N
N
O
N
N
O
S
O
N
H3C
CH2CO2H
7
8
N
H3C
CH2CO2H
Fig. 1. Structures of compounds 1e8.
During the preparation of compound
1
from 2-amino-
The 1H and 13C NMR data for all the compounds confirmed the
naphthalene, a mixture of three compounds was obtained. Chro-
matographic purification of this mixture gave compound 1 (49%)
and the alcohol 2a (10%) which is explained by hydrolysis. In
the 1H-NMR of the crude mixture the characteristic pattern of the
vinyl protons for compound 3, formed by elimination, could be
observed. This third compound, however, was not isolated by
chromatography, as it was present in trace amounts only.
When the above impure mixture was treated with triethylamine
and mesyl chloride [19] the vinyl compound 3, was obtained in 20%
yield; the same treatment of 2a gave 3 in 22% yield. The formation
of the vinyl sulfone was readily confirmed by 1H NMR analysis
which showed the expected splitting pattern for the vinyl protons.
Diazotization of 2-[(3-aminophenyl)sulfonyl]-1-ethanol and
coupling (pH 7) with 2-aminonaphthalene, followed by heating
with copper acetate in a mixture of pyridine and water, afforded the
alcohol 5, presumably through cyclisation of an intermediate such
as 4, that was not isolated. 2b was prepared by the same method
starting from 3-aminonaphthalene-1-sulfonic acid and 2-[(4-ami-
nophenyl)sulfonyl]ethyl hydrogen sulfate in low overall yield (9%).
The procedure described above for the preparation of 3 was also
used to prepare the vinyl compound 6 from the alcohol 5 in 33%
yield.
proposed structures (Tables 1 and 2).
2.2. Spectral data
Acetonitrile (HPLC grade, SigmaeAldrich Co.) was chosen as
solvent for spectral measurements, taking into account the position
of the bands in the absorption spectrum and the low solubility of
the compounds under study in apolar solvents.
The shapes of the absorption and emission spectra for all the
compounds are very similar to those of compound 3 (Fig. 2).
The first absorption band of the triazoles consists of two
vibronic bands; the long-wave absorption maxima are located
at w360 nm for the p-derivatives, and at w355 nm for the
m-derivatives.
Regarding vibrational structure and high intensity of the first
absorption band (absorption coefficient is about 17,000 L molꢀ1
cmꢀ1, see below), this band corresponds to S0eS1(
p,p*) transitions.
The intense sharp short-wavelength absorption band with
maximum at ca. 290 nm (Fig. 2) probably corresponds to the local
absorption of the substituted phenyl ring.
The slight hypsochromic shift observed for the absorption bands
of m-derivatives compared with that of p-derivatives is probably
due to an increase of the dihedral angle between the triazole and
phenyl rings in the case of m-derivatives or/and to conjugative
electronic effects.
The position and the shape of the fluorescence spectra (curve 2
in Fig. 2) were found to be independent of excitation wavelength
both at 290 and 340 nm. The positions of fluorescence maxima are
practically of the same value: w380 nm for p-derivatives and
w360 nm for m-derivatives.
Compound 7 was obtained using a sequence involving an ipso-
coupling reaction [20] between the 4-[(2-sulphatoethyl)-sulfonyl]
benzenediazonium sodium salt and 2-aminonaphthalene-1-
sulfonic acid (displacement coupling with loss of the sulfonic acid
group), followed by oxidation with copper acetate in a mixture of
pyridine and water and finally reaction with sarcosine, perhaps via
intermediate 9 (Scheme 2). Compound 8 was obtained (55% yield)
by addition of sarcosine to vinyl derivative 6.
+
H2N
NH2
N2
N
N
NaNO2
Cu(OAc)2
N
R
N
R'
N
NH2
R
R'
R=SO2CH2CH2OSO3H
R'=SO2CH2CH2OSO3Na
Scheme 1. Synthesis of compound 1.

190
A.M.F. Oliveira-Campos et al. / Dyes and Pigments 87 (2010) 188e193
+
SO3H
NH2
N2
N
NaOH
+
N
SO2CH2CH2OSO3Na
NH2
1. sarcosine
2. Cu(OAc)2
-
SO2CH2CH2OSO3
9
O
S
N
N
O
N
CH3
N
7
CH2CO2H
Scheme 2. Synthesis of compound 7: 2-aminonaphthalene-1-sulfonic acid as secondary component (ipso-coupling).
The Stokes shifts of the studied compounds are very small,
(J) are given in Hz. Double resonance, HMQC (heteronuclear
multiple quantum coherence) and HMBC (heteronuclear multiple
bond correlation) experiments were carried out for complete
assignment of 1H and 13C signals in the NMR spectra. IR spectra were
recorded on a Perkin Elmer FTIR 1600. High-resolution mass spectra
(EI) were obtained on an AutoSpec E spectrometer and ESI mass
spectrum on a LCeMS Finnigan LXQ spectrometer. UV/vis spectral
data were measured in acetonitrile (HPLC grade, SigmaeAldrich
Co.) solutions in 1-cm quartz cuvette. Absorption spectra were
recorded using a PerkineElmer Lambda 35 spectrophotometer.
Fluorescence emission spectra were recorded using a PerkineElmer
LS 55 spectrophotometer; excitation wavelength was 340 nm.
Excitation at 340 nm was selected because it corresponds to the
absorption maximum of the second vibronic band of S0 / S1
transition and does not overlap with the fluorescence spectrum.
Fluorescence emission spectra were corrected for characteristics of
the emission monochromator and the photomultiplayer response.
Fluorescence quantum yields qF of triazoles were referred to
1-aminonaphthalene as fluorescence standard (qF ¼ 39% [4]). TLC
was carried out on plates coated with silica gel 60 F254. Column
chromatography was performed on silica gel (230e400 mesh)
with light petroleum-ethyl acetate mixtures of increasing polarity,
unless other conditions are described. Light petroleum refers to the
fraction boiling in the range 40e60 ꢁC.
demonstrating a slight difference in geometry between vertical and
relaxed (emitting) states, which may be related to the planarity of
the triazole chromophore.
The fluorescence quantum yields (qF) of triazoles were refer-
enced to that of 1-aminonaphthalene as a fluorescence standard
(1-aminonaphthalene has qF ¼ 39%, [4]) because of the similarity
between its absorption and fluorescence spectra with those of
triazole derivatives.
It is evident that all the studied triazoles fluoresce with high qF
(Table 3). Nonetheless, there is a decrease of fluorescence quantum
yield in the case of the sarcosine derivatives 7 and 8 to 62 and 54%,
respectively.
3. Experimental
3.1. General
Melting points were determined on a Gallenkamp melting point
apparatus and are uncorrected. 1H NMR (300 MHz) and 13C NMR
(75.4 MHz) spectra were recorded on a Varian Unity Plus Spec-
trometer at 298 K or on a Bruker Avance III 400 spectrometer
(400 MHz for 1H and 100.6 MHz for 13C). Chemical shifts are
reported in ppm relative to solvent peak or TMS; coupling constants
Table 1
1H NMR chemical shifts (ppm, in DMSO-d6 except otherwise indicated).
Compound/chemical shift
1
2aa
2b
3b
5
6b
7
8
H4
H5
H6
7.91
7.94
8.55
7.71e7.80
8.08
8.16
8.54
e
7.89
7.95
8.63e8.70
7.74e7.85
8.07e8.12
8.25
8.29
e
7.73
7.77
7.87
7.56e7.74
8.55
8.05
8.54
e
7.80e8.00
7.80e8.00
8.00e8.15
7.60e7.80
8.57
7.71e7.80
7.71e7.80
7.86e7.98
7.60e7.75
8.58e8.68
8.92
7.89e7.93
7.89e7.93
8.50e8.53
7.72e7.75
8.06e8.08
8.18e8.22
8.50e8.53
7.93
7.93
8.58
7.70e7.80
8.64
8.95
H7 and H8
H9
7.70e7.79
8.54e8.59
8.16
8.54e8.59
e
H20
8.74
e
8.77
e
H30
8.66
e
e
H40
8.63
8.58e8.68
7.71e7.80
7.86e7.98
e
8.04e8.11
7.93
8.04e8.11
3.67
H50
8.54
8.16
3.55
3.75
e
8.66
8.25
3.58
3.96e4.08
8.54e8.59
8.16
3.55
3.73
4.92
8.54
8.05
e
7.80e8.00
8.00e8.15
3.61
3.76
no
8.50e8.53
8.18e8.22
4.11
H60
SO2CH2
CH2O
OH
SO2CH]
]CH, trans SO2
]CH, cis SO2
CH2N
CH3N
NCH2CO2
e
e
e
e
no
e
no
e
e
e
e
e
6.71
6.10
6.50
e
6.78
6.16
6.60
e
e
e
e
e
3.82
2.28
3.22
2.93
2.20
3.14
a
Acetone-d6.
CDCl3 no-not observed.
b

A.M.F. Oliveira-Campos et al. / Dyes and Pigments 87 (2010) 188e193
191
Table 2
13C NMR chemical shifts (ppm, in DMSO-d6 except otherwise stated).
Compound/chemical shift
1
2aa
2b
3b
5
6b
7
8
C3a
C4
C5
C5a
143.66
116.20
130.94
132.23
122.93
144.30
117.08
131.71
133.60
123.94
139.64
114.35
146.78
128.99
129.76
144.17
116.07
130.79
132.46
128.97
143.34
116.12
130.64
132.11
129.29
143.96
116.18
130.55 or 130.58 136.31
132.48 137.58
126.95 or 128.87 126.53
144.29
118.87
143.39
116.18
130.65
132.16
124.27
C6
C7
128.27 or 128.50 128.91 or 129.19 127.95 or 127.97 127.77 or 128.09 128.16 or 128.31 127.78 or 127.98 128.34 or 128.50 128.17 or 128.31
C8
C9
C9a
129.40
123.75
142.83
142.67
129.91
120.04
139.57
120.04
129.91
57.76
130.16
125.39
144.99
144.23
130.87
120.87
140.95
120.87
130.87
59.20
122.82
124.17
143.38
142.71
129.97
120.24
142.40
120.24
129.97
57.84
123.34
124.50
143.60
120.13
129.41
120.24
143.70
120.24
129.41
122.86
123.69
142.50
141.85
118.55
139.65
124.17
131.24
127.66
57.61
123.40
124.66
143.38
140.95
119.23
141.30
124.46
130.55 or 130.58 119.02
126.95 or 128.87 136.60
51.31
129.62
127.21
145.10
141.83
136.60
119.02
141.32
122.90
123.77
142.55
141.42
118.62
139.73
129.33
131.22
127.61
52.49
C9b
C10
C20
C30
C40
C50
C60
SO2CH2
CH2O
SO2CH]
]CH2
CH2N
CH3N
NCH2
C]O
55.08
56.74
55.13
55.01
138.11
128.30
137.99
128.98
48.01
49.13
40.87
52.67
39.62
55.63
170.28
171.68
a
Acetone-d6.
CDCl3.
b
Extreme care must be taken in the use and disposal of 2-
naphthylamine, as it is a proven mutagen and carcinogen that is
harmful to health and the environment [21].
mixture was stirred for 30 min. Excess HNO2 (I2-starch test) was
destroyed using amidosulfuric acid.
3.2.2. Azo coupling
To a solution of 2-aminonaphthalene (for compounds 1 and 5)
(7 mmol) in H2O (10.0 mL), concentrated HCl (1.0 mL; 9 mmol) was
added and the mixture heated for 10 min. After cooling, in an ice-
acetone bath, the diazonium salt solution (Section 2.2.1) was added
dropwise, the pH being adjusted to 5 using 5 M aq NaOH solution
and the ensuing mixture was stirred for 1 h. When coupling was
complete (H-acid test), the pH was adjusted to 7, the precipitated
dye was filtered and used in the next step without drying.
In the case of 2b, to a solution of 3-aminonaphthalene-1-
sulfonic acid (2.23 g; 10 mmol) in H2O (10 mL) was added 5 M aq
NaOH (2.0 mL; 10 mmol). After cooling in an ice-acetone bath, the
diazonium salt solution was added dropwise and the procedure
described above was followed.
3.2. General procedures for the synthesis of compounds
1, 2b, 5 and 7
3.2.1. Diazotization
To a solution of 2-[(4-aminophenyl)sulfonyl]ethyl hydrogen
sulfate (5.7, 10 and 6 mmol for compounds 1, 2b and 7, respectively)
or 2-[(3-aminophenyl)sulfonyl]ethan-1-ol (6 mmol, for compound
5, in H2O (13.0 mL), was slowly added concentrated HCl (2.8 mL;
25 mmol). The reaction mixture was cooled to 0e5 ꢁC and 5 M
NaNO2 (0.27 mL mmolꢀ1 of substrate) was added dropwise; the
2
Table 3
Absorption maxima (Amax), fluorescence maxima (Fmax) and fluorescence quantum
yields (qF) of derivatives of 2H-naphto[1,2-d][1,2,3]triazol-2-yl)benzene in
acetonitrile.
2
1
1
0
a
Compound
Amax
(nm)
Fmax
qF
(%)
(nm)b
m
N
N
p
N
R
1
eSO2CH2CH2OSO3H (p)
eSO2CH2CH2OSO3H (p), R]SO3H
eSO2CH2CH2OH (p)
eSO2CH2CH2OH (m)
eSO2CH]CH2 (p)
eSO2CH]CH2 (m)
eSO2CH2CH2N(CH3)CH2CO2H (p)
eSO2CH2CH2N(CH3)CH2CO2H (m)
360
360
360
353
360
354
360
354
380
380
375
362
380
363
380
362
82
80
83
81
82
81
62
54
2b
2a
5
3
6
200
300
400
500
7
8
Wavelength (nm)
a
R]H, except otherwise indicated.
Fluorescence spectra were excited at 340 nm.
Fig. 2. UV/vis absorption (1) and fluorescence emission (2) spectra of compound 3 in
CH3CN at room temperature. Fluorescence spectrum was excited at 340 nm.
b

192
A.M.F. Oliveira-Campos et al. / Dyes and Pigments 87 (2010) 188e193
3.2.3. Oxidation with copper acetate
ammonium chloride, dried (anhydrous MgSO4) and concentrated
under vacuum. The residue was purified by crystallization from
chloroform/diethyl ether yielding the title compound as a light
To the above dye (obtained as described in Section 3.2.2), pyri-
dine (5.0 mL), H2O (2.0 mL) and Cu(OAc)2 (2.5 g; 13.8 mmol) were
added and the mixture was refluxed (15 min for compounds 1 and
2b; 30 min for compound 5) and then poured into water. The
precipitated solid was filtered and dried; recrystallization from
ethanol afforded the final compound.
brown solid (0.068 g, 22%), m.p. 195e196 ꢁC (dec). UV lmax
(3): 284
(2.55 ꢂ 104), 342 (1.72 ꢂ 104), 358 (1.66 ꢂ 104) nm. 1H NMR
(300 MHz, CDCl3):
d
¼ 6.10 (d, J ¼ 9.6 Hz, 1H, .dbnd;CH, trans SO2),
6.50 (d, J ¼ 16.5 Hz, 1H, ]CH, cis SO2), 6.71 (dd, J ¼ 16.5, 9.6 Hz, 1H,
SO2CH), 7.56e7.74 (m, 2H, H-7, H-8), 7.73 (d, J ¼ 9.0 Hz, 1H, H-4),
7.77 (d, J ¼ 9.0 Hz, 1H, H-5), 7.87 (dd, J ¼ 7.5, 1.5 Hz, 1H, H-6), 8.05
(d, J ¼ 9.0 Hz, 2H, H-20, H-60), 8.54 (d, J ¼ 9.0 Hz, 2H, H-30, H-50),
3.3. Synthesis and characterization of compounds 1e8
3.3.1. 2-{[4-(2H-Naphtho[1,2-d][1,2,3]triazol-2-yl)-
8.55 (d, J ¼ 7.5 Hz, H-9). 13C NMR (75.4 MHz, CDCl3):
d
¼ 116.07
phenyl]sulfonyl}ethyl hydrogen sulfate (1)
(C-4), 120.13 (C-10), 120.24 (C-30, C-50), 123.34 (C-9), 124.50 (C-9a),
127.77 and 128.09 (C-7, C-8), 128.30 (]CH2), 128.97 (C-6), 129.41
(C-20, C-60), 130.79 (C-5), 138.11 (SO2C]), 132.46 (C-5a), 143.60
(C-9b), 143.70 (C-40), 144.17 (C-3a). HRMS calcd. for C18H13N3SO2:
335.0728. Found: (M)þ335.0725.
Yield: 1.2 g, 49%, m.p. 169e172 ꢁC. UV lmax
(
3
): 284 (2.55 ꢂ 104),
342 (1.72 ꢂ 104), 358 (1.66 ꢂ 104) nm. 1H NMR (300 MHz, DMSO-
d6):
d
¼ 3.55 (t, J ¼ 6.0 Hz, 2H, SO2CH2), 3.75 (t, J ¼ 6.3 Hz, 2H,
CH2O), 7.71e7.80 (m, 2H (H-7, H-8), 7.91 (d, J ¼ 9.3 Hz,1H, H-4), 7.94
(d, J ¼ 9.0 Hz, 1H, H-5), 8.08 (dd, J ¼ 2.1, 6.6 Hz, 1H, H-9), 8.16 (d,
J ¼ 9.0 Hz, 2H, H-20, H-60), 8.54 (d, J ¼ 9.0 Hz, 2H, H-30, H-50), 8.55
(dd, J ¼ 2.1, 6.6 Hz, 1H, H-6)). 13C NMR (75.4 MHz, DMSO-d6):
3.3.5. 2-{[3-(2H-Naphtho[1,2-d][1,2,3]triazol-2-yl)-
phenyl]sulfonyl}ethan-1-ol (5)
d
¼ 55.08 (CH2O), 57.76 (SO2CH2), 116.20 (C-4), 120.04 (C-30, C-50),
Yield: 0.86 g, 41%, m.p. 158e159 ꢁC. UV lmax
(
3
): 282 (2.52 ꢂ 104),
122.93 (C-6), 123.75 (C-9a), 128.27 and 128.50 (C-7, C-8), 129.40
(C-9), 129.91 (C-20, C-60), 130.94 (C-5), 132.23 (C-5a), 139.57 (C-40),
142.67 (C-10), 142.83 (C-9b), 143.66 (C-3a). HRMS calcd for
C18H15N3S2O6: 433.0402. Found: (M ꢀ 1)þ432.0313.
338 (1.69 ꢂ 104), 355 (1.63 ꢂ 104) nm. 1H NMR (300 MHz, DMSO-
d6):
d
¼ 3.61 (t, J ¼ 6.0 Hz, 2H, SO2CH2), 3.76 (t, J ¼ 6.0 Hz, 2H,
CH2O), 7.60e7.80 (m, 2H, H-7, H-8), 7.80e8.00 (m, 3H, H-4, H-5,
H-50), 8.00e8.15 (m, 2H, H-60, H-6), 8.57 (dd, J ¼ 7.5, 1.2 Hz, 1H,
H-9), 8.63 (dd, J ¼ 7.8, 1.2 Hz, 1H, H-40), 8.74 (t, J ¼ 1.2 Hz, 1H, H-20).
The mother liquor was extracted with ethyl acetate and the
combined organic extracts were dried (anhydrous MgSO4) and the
oily residue obtained was subjected to column chromatography
(EtOAc/light petroleum 5:1) yielding compound 2a (0.2 g, 10%, m.p.
201e202 ꢁC).
OH not observed. 13C NMR (75.4 MHz, DMSO-d6):
d
¼ 55.01 (CH2O),
57.61 (SO2CH2), 116.12 (C-4), 118.55 (C-20), 122.86 (C-9), 123.69 (C-
9a), 124.17 (C-40) 127.66 (C-60), 128.16 and 128.31 (C-7, C-8), 129.29
(C-6), 130.64 (C-5), 131.24 (C-50), 132.11 (C-5a), 139.65 (C-30), 141.85
(C-10), 142.50 (C-9b), 143.34 (C-3a). HRMS calcd. for C18H15N3SO3:
353.0834. Found: (M)þ353.0845.
3.3.2. 2-{[4-(2H-Naphtho[1,2-d][1,2,3]triazol-2-yl)-
phenyl]sulfonyl}ethan-1-ol (2a)
UV lmax
(
3
): 284 (2.60 ꢂ 104), 342 (1.74 ꢂ 104), 358 (1.70 ꢂ 104)
3.3.6. 2-[3-(Vinylsulfonyl)phenyl]-2H-naphtho-
[1,2-d][1,2,3]triazole (6)
nm. 1H NMR (300 MHz, acetone-d6):
d
¼ 3.58 (t, J ¼ 6.3 Hz, 2H,
SO2CH2), 3.96e4.08 (m, 3H, CH2O and OH), 7.74e7.85 (m, 2H, H-7,
H-8), 7.89 (d, J ¼ 9.3 Hz, 1H, H-4), 7.95 (d, J ¼ 9.3 Hz, 1H, H-5),
8.07e8.12 (m, 1H, H-9), 8.25 (d, J ¼ 9.0 Hz, 2H, H-20, H-60), 8.66 (d,
J ¼ 9.0 Hz, 2H, H-30, H-50), 8.63e8.70 (m, 1H, H-6). 13C NMR
To a dichloromethane (4.7 mL) solution of alcohol 5 (0.52 g;
1.47 mmol) maintained at 0 ꢁC, triethylamine (0.51 mL, 3.7 mmol)
and mesyl chloride (0.14 mL; 1.8 mmol) were added and the mixture
was stirred for 10 min. The solution was washed with saturated
ammonium chloride solution, dried (anhydrous MgSO4) and then
concentrated under vacuum. The oily residue was purified by flash
column chromatography (chloroform: methanol, 10:1). The first
fraction gave the title product as a light-brown solid (0.16 g, 33%), m.
(75.4 MHz, acetone-d6):
d
¼ 56.74 (CH2OH), 59.20 (SO2CH2), 117.08
(C-4), 120.87 (C-30, C-50), 123.94 (C-6), 125.39 (C-9a), 128.91 and
129.19 (C-7, C-8), 130.16 (C-9), 130.87 (C-20, C-60), 131.71 (C-5),
133.60 (C-5a), 140.95 (C-40), 144.23 (C-10), 144.30 (C-3a), 144.99
(C-9b). HRMS calcd. for C18H16N3SO3: 354.0912 (M þ 1)þ. Found:
(M þ 1)þ354.0913.
p. 167e168 ꢁC. UV lmax
(3
): 281 (2.22 ꢂ 104), 339 (1.39 ꢂ 104), 354
(1.30 ꢂ 104) nm. 1H NMR (300 MHz, CDCl3):
d
¼ 6.16 (d, J ¼ 9.6 Hz,
1H, ]CH, trans SO2), 6.60 (d, J ¼ 16.5 Hz,1H, ]CH, cis SO2), 6.78 (dd,
J ¼ 16.5, 9.6 Hz, 1H, SO2CH), 7.60e7.75 (m, 2H, H-7, H-8), 7.71e7.80
(m, 3H, H-4, H-5, H-50), 7.86e7.98 (m, 2H, H-6, H-60), 8.58e8.68 (m,
2H, H-9, H-40), 8.92 (t, J ¼ 1.8 Hz, 1H, H-20). 13C NMR (75.4 MHz,
3.3.3. 2-{4-[(2-Hydroxyethyl)sulfonyl]phenyl}-2H-
naphtho[1,2-d][1,2,3]triazole-5-sulfonic acid (2b)
Yield: 0.39 g, 9%, m.p. 172e175 ꢁC. UV lmax
(3
): 283 (2.50 ꢂ 104),
342 (1.70 ꢂ 104), 358 (1.64 ꢂ 104) nm. 1H NMR (300 MHz, DMSO-
CDCl3):
d
¼ 116.18 (C-4), 119.23 (C-20), 123.40 (C-9), 124.46 (C-40),
d6):
d
¼ 3.55 (t, J ¼ 6.0 Hz, 2H, SO2CH2), 3.73 (apparent q, J ¼ 6.0 Hz,
124.66 (C-9a), 126.95 (C-60or C-6), 127.78 and 127.98 (C-7, C-8),
128.87 (C-60 or C-6), 128.98 (]CH2), 130.55 and 130.58 (C-5, C-50),
137.99 (SO2CH), 132.48 (C-5a), 140.95 (C-10), 141.30 (C-30), 143.38
(C-9b), 143.96 (C-3a). HRMS calcd. for C18H14N3SO2: 336.0807.
Found: (M þ 1)þ336.0812.
2H, CH2O), 4.92 (t, J ¼ 6.0 Hz, 1H, OH), 7.70e7.79 (m, 2H, H-7, H-8),
8.29 (s, 1H H-4), 8.16 (d, J ¼ 9.0 Hz, 2H, H-20, H-60), 8.54e8.59 (m,
3H, H-9, H-30, H-50), 8.95 (dd, J ¼ 7.2, 2.0 Hz, 1H, H-6). 13C NMR
(75.4 MHz, DMSO-d6):
d
¼ 55.13 (CH2O), 57.84 (SO2CH2), 114.35 (C-
4), 120.24 (C-30, C-50), 122.82 (C-9), 124.17 (C-9a), 127.95 and 127.97
(C-7, C-8), 128.99 (C-5a), 129.76 (C-6), 139.64 (C-3a), 129.97 (C-20, C-
60), 142.40 (C-40), 142.71 (C-10), 143.38 (C-9b), 146.78 (C-5). HRMS
calcd. for C18H15N3S2O6: 433.0402. Found: (M ꢀ 1)þ432.0313.
3.3.7. 2-{[4-(2H-Naphtho[1,2-d][1,2,3]triazol-2-yl)-
phenyl]sulfonyl}ethyl (methyl)carbamic acid (7)
To a suspension of 2-aminonaphthalene-1-sulfonic acid (1.37 g;
6 mmol) in H2O (10.0 mL), 5 M aq NaOH (1.2 mL) was added. The
solution obtained was cooled to 0e5 ꢁC, and the diazonium salt
solution (Section 2.2.1) was added portion wise, keeping the
temperature below 5 ꢁC and at pH 8 by the addition of 5 M aq NaOH
solution. The azo coupling was complete aftere2 h (H-acid test) and
the pH of the reaction mixture was lowered to 4 using aq HCl
solution. The azo dye formed was collected by filtration.
3.3.4. 2-[4-(Vinylsulfonyl)phenyl]-2H-
naphtho[1,2-d][1,2,3]triazole (3)
To a dichloromethane (3.2 mL) solution of 2a (0.32 g; 0.9 mmol)
maintained at 0 ꢁC, was added triethylamine (0.35 mL; 2.5 mmol)
and mesyl chloride (0.1 mL; 1.3 mmol) and the resulting mixture
was stirred for 10 min. The solution was washed with saturated

A.M.F. Oliveira-Campos et al. / Dyes and Pigments 87 (2010) 188e193
193
The moist dye was suspended in water (12 mL), sarcosine
(0.71 g; 8 mmol) was added and the pH adjusted to 8 by the
addition of 5 M aq NaOH solution. The mixture was heated at 60 ꢁC
for 2 h, cooled to 5 ꢁC and the pH adjusted to 5 using aq HCl solu-
tion. The dye obtained was salted out by the addition of 3 g NaCl
and collected by filtration.
but derivatives containing sarcosine showed lower fluorescence,
although still significant (54 and 62%).
The successful reaction of vinylsulfonyl precursors with sarcosine
suggests that they may also react with more complex biomolecules.
Acknowledgments
The filter cake was dissolved in pyridine (5.0 mL) and water
(5.0 mL). Cupric acetate (2.5 g; 13.8 mmol) was added with stirring
and the mixture was heated at 60 ꢁC for 4 h. After cooling it was
poured into 100 mL cold water and the precipitate was collected
and dried at 30 ꢁC. The crude product 7 was obtained in 94% yield
(2.40 g). A pure sample of 7 for spectroscopic analysis was obtained
by repeated mixing with acidified water (pH 1) and filtration,
which removed the remaining pyridine and copper salts; m.p.
We gratefully acknowledge the FCT (Fundação para a Ciência e
Tecnologia) and FEDER for financial support (REEQ/630/QUI/2005,
for LCMS). The Bruker Avance II 400 spectrometer is part of the
National NMR network and was purchased under the framework
of the National Programme for Scientific Re-equipment, contract
REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and
(FCT). We are also grateful for research grant VZ MSMT-0021627501,
Czech Republic.
180e181 ꢁC. UV lmax
(
3
): 282 (2.30 ꢂ 104), 338 (1.40 ꢂ 104), 355
(1.29 ꢂ 104) nm. 1H NMR (300 MHz, DMSO-d6):
d
¼ 2.28 (s, 3H,
We thank Ms. E. Pinto for recording NMR spectra and for
performing elemental analyses and Ms. N. Nunes for LCMS
determinations.
CH3), 3.22 (s, 2H, CH2CO2H), 3.82 (t, J ¼ 6.0 Hz, 2H, NCH2), 4.11 (t,
J ¼ 6.0 Hz, 2H, SO2CH2), 7.72e7.75 (m, 2H, H-7, H-8), 7.89e7.93 (m,
2H, H-4, H-5), 8.06e8.08 (m,1H, H-9), 8.18e8.22 (m, 2H, H-20, H-60),
8.50e8.53 (m, 3H, H-30, H-50, H-6), the OH was not observed. 13C
References
NMR (75.4 MHz, DMSO-d6):
d
¼ 39.62 (CH3), 48.01 (CH2N), 51.31
(SO2CH2), 55.63 (CH2CO2H), 118.87 (C-4), 119.02 (C-30, C-50), 126.53
(C-6), 127.21 (C-9a), 128.34 and 128.50 (C-7, C-8), 129.62 (C-9),
136.31 (C-5), 136.60 (C-20, C-60), 137.58 (C-5a), 141.32 (C-40), 141.83
(C-10), 144.29 (C-3a), 145.10 (C-9b), 170.28 (C]O).
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3.3.8. 2-{[3-(2H-Naphtho[1,2-d][1,2,3]triazol-2-yl)-
phenyl]sulfonyl}ethyl (methyl)carbamic acid (8)
The pH of a solution of sarcosine (0.029 g; 0.33 mmol) in H2O
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1H NMR (400 MHz, DMSO-d6):
d
¼ 2.20 (s, 3H, CH3N), 2.93 (t,
J ¼ 5.4 Hz, 2H, CH2N), 3.14 (s, 2H, CH2CO2H), 3.67 (t, J ¼ 5.4 Hz, 2H,
SO2CH2), 7.70e7.80 (2H, m, H-7, H-8), 7.93 (apparent t, J ¼ 8.4 Hz,
3H, H-4, H-5, H-50), 8.04e8.11 (2H, m, H-40, H-60), 8.58 (d, J ¼ 6.6 Hz,
1H, H-6), 8.64 (d, J ¼ 6.6 Hz, 1H, H-9), 8.77 (t, J ¼ 1.5 Hz, 1H, H-20),
OH not observed. 13C NMR (100.6 MHz, DMSO-d6): 40.87 (CH3N),
49.13 (CH2N), 52.49 (SO2CH2), 52.67 (CH2 CO2H), 116.18 (C-4),
118.62 (C-20), 122.90 (C-9), 123.77 (C-9a), 124.27 (C-6), 127.61 (C-60),
128.17 and 128.31 (C-7, C-8), 129.33 (C-40), 130.65 (C-5), 131.22 (C-
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(C-3a), 171.68 (C]O). MS, ESIþ: 425.33 ((M þ 1)þ, 3%); 379.25
[(M þ 1)þeCO2H, 100%].
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4. Conclusions
A series of compounds derived from naphthotriazole and con-
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Due to their reactivity towards nucleophiles and their high
fluorescence quantum yields, these compounds are promising
fluorescent markers.
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