Synthesis and Fe3+ recognition of novel triazole Schiff-base derivatives bearing fluorogenic naphthalene and anthracene units

Article abstract of DOI:10.3184/174751914X14116648115995

Novel triazole Schiff-bases derivatives have been synthesised from 3,5-diaryl-4-amino-1,2,4-triazole with naphthaldehyde and anthraldehyde. The emission spectrum of 3,5-diphenyl-4-(anthrylmethyleneamino)-1,2,4-triazole exhibited fluorescent quenching upon

Full text of DOI:10.3184/174751914X14116648115995

JOURNAL OF CHEMICAL RESEARCH 2014
VOL. 38 OCTOBER, 627–629
RESEARCH PAPER 627
3
+
Synthesis and Fe recognition of novel triazole Schiff-base derivatives
bearing fluorogenic naphthalene and anthracene units
a
a
a
a
a
a
b
Wei Wang , Xiaolong Yu , Qiang Zhang , Mingzhu Li , Xiaoyu Jiang , Qinglei Liu and Yan Gao *
aSchool of Perfume and Aroma Technology, Shanghai Institute of Technology, Shanghai 200235, P.R. China
bDepartment of Chemical Engineering, University of Science and Technology Liaoning, Anshan, 114051, P.R. China
Novel triazole Schiff-bases derivatives have been synthesised from 3,5-diaryl-4-amino-1,2,4-triazole with naphthaldehyde
and anthraldehyde. The emission spectrum of 3,5-diphenyl-4-(anthrylmethyleneamino)-1,2,4-triazole exhibited fluorescent
3
+
quenching upon chelation to Fe ions.
Keywords: Schiff-bases, naphthalene, anthracene, fluorescence, Fe3+ recognition
3
+
+
3+
2+
+
3+
The development of artificial receptors for the sensing and
recognition of important species has been actively investigated
Fe , Na , Al , Mg , Ag and Cr , the results of UV-Vis spectra
showed that compound 2a demonstrated selective recognition
of Fe . As shown in Fig. 1, compound 2a displayed a marked
1–3
3+
in recent years. In this regard, metal-selective fluorescent
probes have been widely exploited to detect biologically- or
blue shift in the maximum absorption wavelength only with
4
–6
3+
environmentally-relevant metal ions. Very few fluorescent
Fe among the various metal ions examined, while no change
3
+
7,8
sensors for Fe have been reported, so there is a need f to
was observed after adding the other metal ions.
The fluorescence quenching effects of various metal ions
on compound 2a (1×10 M) in CH Cl /DMF solution at room
temperature were investigated (Fig. 2).
When Fe was added to compound 2a, the fluorescence
intensity was significantly quenched, and there was a decrease
of about five-fold of emission intensity. Different anions
3
+
explore new systems that recognise Fe . The most powerful
approach seems to design small and simple synthetic molecules
that combine a Fe binding unit with a fluorophore. Significant
change in either fluorescence intensity or wavelength on Fe
coordination occurs, making it a suitable analytical tool.
–
5
2
2
3
+
3
+
3+
We now report the synthesis, characterisation and
3
+
fluorescence Fe sensing properties in CH Cl /DMF media
2
2
of four Schiff-bases with naphthalene and anthracene as
fluorophore and the imino-group as ionophore. The ligands 2a
3
+
(
Scheme 1) show fluorescent quenching in presence of Fe ion,
but in presence of other metal ions emission intensities of the
3
+
ligands either decrease or remain unaltered. Thus Fe ion can
be detected in presence of other metal ions.
Results and discussion
The target products were synthesised using a two-step
procedure as shown in Scheme 1. (i) Synthesis of 3,5-diaryl-4-
amino-1,2,4-triazole 1 via the cycloaddition reaction between
substituted benzonitriles with hydrazine hydrate; (ii) Synthesis
of triazole Schiff-bases derivatives (2a–d) by condensation
reaction of 1 with naphthaldehyde and anthraldehyde. The
target compounds were characterised by elemental analysis,
1
13
H NMR, C NMR, IR and MS; the spectral data were in
agreement with the proposed structures.
The complexation properties of compounds 2a–d were
studied toward various heavy metal and transition metal
cations, including Ca , Cd , Cu , Hg , Mn , Ni , Pb , Zn ,
Fig. 1 UV-Vis spectra of compound 2a (10ꢀμM) upon addition of various
metal ions (20ꢀμM) in CH Cl and DMF (v/v=9:1).
2+
2+
2+
2+
2+
2+
2+
2+
2
2
N N
N
NH NH2 H O, (NH ) SO
4
Ar-CHO
CH COOH, reflux
2
2
2 2
R
R
R
CN
HOCH CH OH
3
2
2
H2N
1
N N
R
R
2a, R=H, Ar=
2c, R=H, Ar=
2b, R=CF , Ar=
3
N
N
OH
OH
R=CF , Ar=
HC
Ar
2d,
3
2a-2d
Scheme 1 Synthesis of compounds 2a–d.
*
Correspondent. E-mail: zjq20080901@126.com
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628 JOURNAL OF CHEMICAL RESEARCH 2014
Fig. 2 Fluorescence emission spectra of compound 2a (10ꢀμM) upon
3
+
addition of Fe (20ꢀμM) in CH Cl and DMF (v/v=9:1).
2
2
3+
Fig. 4 Job’s plot for determining the stoichiometry of receptor 2a and Fe
ion in CH Cl and DMF (v/v=9/1), I and I are the fluorescence intensity of
2
2
0
3
+
2
a in the presence and absence of Fe , respectively, the total concentration
(
e.g. chloride, nitrate, acetate, etc.) have almost no effect on
emission intensity when Fe is added to the ligand. That means
that the decrease in the emission intensity of the ligand is due
to presence of Fe ion only, not because of the anion present
in the Fe -salt. Fluorescence quenching observed for 2a is
attributed to the chelation-enhanced fluorescence quenching
CHEQ) effect. Minimal or no changes were observed with
the other metal ions (the curves were omitted). Thus it may be
concluded that 2a has special selectivity for Fe .
3+
of 2a and Fe ion is 0.1 mM (λ =326 nm).
ex
3
+
3
+
In conclusion, four new triazolethione Schiff bases
derivatives were designed and synthesised. Compound 2a
displayed selective UV‑Vis and fluorescence changes upon
the addition of iron ion. This system provided an interesting
example for probing the Fe binding process. The design of
Schiff bases hosts for the selective binding of various ions is
currently under investigation.
3
+
(
3
+
3
+
3
+
The titration of probe 2a by Fe with an excitation at
λex =326 nm, is given in Fig. 3 as an example. The fluorescence
Experimental
spectrumexhibitedadecreaseofitsemissionintensityat498 nm
9
10,11
3,5-Diaryl-4-amino-1,2,4-triazol
1
and anthraldehyde
were
and a single set of isosbestic points was observed, suggesting a
single equilibrium was reached during complexation. From the
titrations, we determined the binding constant of probe 2a for
prepared according to the literature, other reactants and chemicals
were obtained from commercial sources and used without
further purification. Elemental analyses were made with a CHN
CODRDER MT-3. IR spectra were obtained with a PerkinElmer
3
+
6
Fe (K =2.14×10 ).
a
Fitting the changes in fluorescence spectra of probe 2a
spectrophotometer. Mass spectral data were obtained on an Agilent
3
+
with Fe ions, we applied the method of continuous variation
Job’s plot) to confirm the complexation ratio between 2a and
1
1
100 LC/MS. H NMR was recorded at room temperature on a Bruker
(
Avance-500 NMR spectrometer. Chloroform (CDCl ) was used as
3
3
+
Fe ions. As shown in Fig. 4, the maximum point at the mole
solvent and TMS as internal standard. UV-Vis absorption spectra were
recorded at room temperature on a Lambda-900 spectrometer. The
fluorescence emission spectra were measured on a LS-55 spectrometer.
fraction of 0.33 indicates the complexation ratio of probe 2a
3
+
and Fe is 2:1.
Fig. 3 Fluorescence emission spectra of probe 2a (10 μM) as a function of various concentration of iron in a mixture of CH Cl and DMF (v/v=9:1)
2
2
(
λex =326 nm).
JCR1402733_FINAL.indd 628
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JOURNAL OF CHEMICAL RESEARCH 2014 629
Synthesis of the target compounds 3,5-diaryl-4-arylmethyleneamino-
,2,4-triazole (2a–d); general procedure
,5-diaryl-4-amino-1,2,4-triazole 1 (0.02 mol) was added to a mixture
of anthraldehyde (0.02 mol), glacial acetic acid (3 mL) in ethanol
20 mL) and the mixture was refluxed for 8 h, cooled and filtered.
(1H, d, J=9.0 Hz, ArH), 7.923 (5H, t, J=8.0 Hz, ArH), 7.593 (1H, t,
J=7.5 Hz, ArH), 7.451 (1H, t, J=7.5 Hz, ArH), 7.183 (1H, d, J=9.0 Hz,
1
3
13
ArH); C NMR (500 MHz, CDCl ): δ (ppm) 173.89, 166.21, 154.81,
3 C
142.24, 136.70, 135.69, 135.30, 135.04, 134.79, 134.41, 134.30, 133.17,
131.06, 131.03, 130.22, 129.35, 129.00, 128.05, 123.39, 113.26. MS,
(
+
The resulting solid product was recrystallised from alcohol to give the
m/z: 527.5 (M+H ). Anal. calcd for C H N OF : C, 61.60; H, 3.06; N,
2
7
16
4
6
target products 2a–d.
10.64; found: C, 61.53; H, 3.08; N, 10.68%.
3
,5-Diphenyl-4-(anthrylmethyleneamino)-1,2,4-triazole (2a): Yield
3
+
Synthesis of the 2a–Fe complex
A solution of FeCl ·6H O (0.81 g, 3.0 mmol) in N,N-dimethyl-
5
1
5%; m.p. 249–251 °C (dec); FTIR (KBr): 3005, 2942, 2859, 1634,
605, 1484, 1218, 832; H NMR (DMSO‑d6):δ (ppm) 9.258 (1H,
s, N=CH), 8.560 (1H, s, ArH), 8.029 (6H, m, ArH), 7.881 (2H, d,
J=9.0 Hz, ArH), 7.542 (6H, t, J=3.5 Hz, ArH), 7.484 (2H, t, J=7.0 Hz,
ArH), 7.362 (2H, t, J=8.0 Hz, ArH); C NMR (500 MHz, CDCl ): δC
ppm) 167.59, 151.19, 133.51, 131.04, 130.07, 129.33, 129.30, 129.08,
28.18, 126.90, 125.63, 124.07, 121.14. MS, m/z: 425.5 (M+H ). Anal.
calcd for C H N : C, 82.05; H, 4.75; N, 13.20; found: C, 81.98; H, 4.78;
1
3
2
H
formamide (5 mL) was mixed with a solution of 2a (2.54 g, 6.0 mmol)
in dichloromethane (25 mL) and the resulting suspension was heated
at 70 °C for 4 h, until a brownish precipitate formed. The solid was
filtered off while hot, washed with water and ethanol, and dried under
reduced pressure. Yield 61%; m.p.>300 °C (dec); FTIR (KBr): 3018,
623, 1596, 1466, 1203, 827, 467 (Fe–N); MS, m/z: 976.9 (FeL +H ).
13
3
(
1
+
+
1
2
2
9
20
4
Anal. calcd for C H FeN Cl : C, 75.73; H, 4.38; N, 12.18; found: C,
58
40
8
2
N, 13.25%.
,5-bis[4-(Trifluoromethyl)phenyl]-4-(anthrylmethyleneamino)-
,2,4-triazole (2b): Yield 23%; m.p. 288–289 °C (dec); FTIR (KBr):
7
5.78; H, 4.36; N, 12.14%.
3
1
3
We acknowledge the financial support of the Key Laboratory
Project (2008S127).
1
011, 2953, 2864, 1630, 1595, 1492, 1235, 829; H NMR (500 MHz,
CDCl ): δ (ppm) 9.274 (1H, s, N=CH), 8.579 (1H, s, ArH), 8.227 (4H,
3
H
m, ArH), 7.897 (4H, d, J=8.0 Hz, ArH), 7.573 (6H, m, ArH), 7.482
Received 24 June 2014; accepted 19 September 2014
Paper 1402733 doi: 10.3184/174751914X14116648115995
Published online: 17 October 2014
13
(
2H, t, J=9.0 Hz, ArH); C NMR (500 MHz, CDCl ): δ (ppm) 172.83,
3 C
1
55.03, 137.66, 135.58, 134.49, 134.06, 133.71, 133.56, 133.28, 131.94,
+
131.69, 130.73, 126.07, 125.83. MS, m/z: 561.5 (M+H ). Anal. calcd
for C H N F : C, 66.43; H, 3.24; N, 9.99; found: C, 66.35; H, 3.26; N,
31
18
4 6
1
0.04%.
References
3,5-Diphenyl-4-(naphthylmethyleneamino)-1,2,4-triazole (2c): Yield
1
2
3
4
5
6
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6
4%; m.p. 234–235 °C (dec); FTIR (KBr): 3276, 3017, 2936, 2878,
2
1
1624, 1598, 1478, 1235, 812; H NMR (500 MHz, CDCl ): δ (ppm)
3 H
10.281 (1H, s, OH), 9.216 (1H, s, N=CH), 8.816 (1H, d, J=8.5 Hz,
ArH), 8.039 (1H, d, J=9.0 Hz, ArH), 7.906 (5H, m, ArH), 7.575 (1H,
t, J=7.5 Hz, ArH), 7.508 (6H, m, ArH), 7.420 (1H, t, J=7.5 Hz, ArH),
13
7.180 (1H, d, J=9.0 Hz, ArH); C NMR (500 MHz, CDCl ): δ (ppm)
3 C
2
008, 37, 1465.
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62, 2927.
168.52, 162.21, 150.74, 137.71, 132.00, 130.25, 129.49, 129.44, 129.28,
128.89, 128.41, 127.16, 124.54, 124.07, 118.68, 108.57. MS, m/z: 391.4
3
+
(
M+H ). Anal. calcd for C H N O: C, 76.91; H, 4.65; N, 14.35; found:
W. Wang, X.Y. Jiang, Q. Zhang, M.Z. Li, X.L. Yu, J.W. Wang and Y. Gao,
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Heterocycl. Commun., 2013, 19, 249 .
2
5
18
4
C, 76.84; H, 4.68; N, 14.39%.
,5-bis[4-(Trifluoromethyl)phenyl]-4-(naphthylmethyleneamino)-
,2,4-triazole (2d): Yield 78%; m.p. 255–256 °C (dec); FTIR (KBr):
7
8
3
1
1
3264, 3010, 2945, 2874, 1618, 1591, 1463, 1250, 805; H NMR
9
I. Yukio, H. Naoto and K. Akikazu, Heterocycl. Commun., 2002, 8, 439.
(500 MHz, CDCl ): δ (ppm) 11.212 (1H, s, OH), 9.232 (1H, s, N=CH),
3
H
10 E. Campaigne and W.L. Archer, J. Am. Chem. Soc., 1953, 75, 989.
11 L.F. Fieser, J.L. Hartwell and J.E. Jones, Org. Synth., 1955, 3, 98.
8
.826 (1H, d, J=8.5 Hz, ArH), 8.159 (4H, d, J=8.0 Hz, ArH), 8.067
JCR1402733_FINAL.indd 629
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