FLUORESCENT PROPERTIES OF 4-N-(2-CARBOXYETHYL)-5CARBOXYAMINOAZOBENZOL-4’-SULFONAT OF SODIUM
E.V. Osintseva 1, L.K. Neudachina 1, N.V. Pechishcheva 2,
Yu.G. Yatluk 3, K.Yu. Shunyaev 2
1
Ural State University
Lenina av., 51, Yekaterinburg 620083, Russia,
2
Institute of metallurgy, Ural division of Russian Academy of sciences
Amundsen st., 101,Yekaterinburg 620016, Russia,
3
Institute of organic synthesis, Ural division of Russian Academy of
sciences, S.Kovalevskaja st, 20, Yekaterinburg 620219, Russia,
Ludmila.Neudachina@usul.ru
Aromatic β-aminopropionic (N-aryl-3- aminopropionic) acids (βAAPA) [1-4] are perspective group of ligands for spectrofotometric [57] and luminescent [8-9] methods. β-AAPA can be used as model
reagents for syntheses of new reagent for analytical chemistry.
Introduction azobenzol-group to structure of aromatic ligands
displaces lightabsorption of reagents and its complexes to visible area of
the spectrum that increases the possibility of the use reagent in optical
method of the analysis. The purpose of persisting work is a study of
fluorescent
characteristic
of
new
N-substituted
aminoazobenzolsulphoacid
4-N-(2-carboxyethyl)amino-5carboxyazobenzol-4'-sulphonat of sodium (I).
For the reason determinations of the optimum conditions of the
reception of fluorescence spectra of solution I the excitation spectra of
solution I are obtained (fig.1).
The most intensive signal in excitation spectra of I exists at λ=250
nm. This wavelength is used for fluorescence excitation of the solution I
to achieve most sensitivity of the signal of fluorescence.
The spectra of fluorescence of solutions I are present on figure 2.
Analysis of spectra of fluorescence of the solution I shows, that the
maximum of intensity of fluorescence is displaced to more short
wavelengths and the quantum yield of fluorescence is increased at
increasing рН of solution. The phenomena of change intensity of
fluorescence of solution I with change pH, probably, is due to process of
ionization of the reagent in aqueous solution.
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1,0
0,9
0,8
2, 3
0,8
0,7
0,6
0,6
0,5
I
I
0,4
0,4
0,3
1
0,2
0,2
0,1
0,0
200
250
300
350
400
450
500
Fig. 1. Spectrum of excitement of
solution I, СI=0.84·10-4М, рН=6.0,
l =1.00 sm, λreg=425 nm, «average»
sensitivity level
0,0
250
550
300
350
400
450
500
Fig. 2. Spectra of fluorescence of
solutions I, СI=0.84·10-4М, l =1.00
sm, λex=250 nm, «average» sensitivity
level: 1 - рН=1.05; 2 - рН=6.13; 3 рН=8.96.
The fluorescence characteristics of aqueous solutions of I and N(2-carboxyethyl)-о-aminobenzoic acid (II) [8] are presented in Table.
Table
Fluorescent characteristics of water solutions of I and II,
CR=1*10-4 М, sensitivity of instrument average
Reagent
I
II [8]
Protonated form
λex/λreg , nm
Imax
250/425
0,074
220/434
25,4
Deprotonated form
λex/λreg , nm
Imax
250/390
0,848
220/411
107,4
The presence of azogroup in structure I promotes the shift of the
maximum of the fluorescence band (protonated and deprotonated forms
of reagent) to short-wave area of the spectrum (=10-20 nm) in
contrast to spectrum of the fluorescence of the solution II. The intensity
of fluorescence of the solution I is much lower then intensities of
fluorescence of the solution II. Notwithstanding settled opinion about
that azocompounds does not fluoresce, studies, called on in given work
show that fluorescence of azocompound I exists, but intensity of
fluorescence comparatively low.
For the reason studies of the influence Cu(II) on fluorescent
characteristics of the solution I the corresponding spectra of
fluorescence of solution I-Cu(II) at different pH were studied. It is
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established that Cu(II) decrease of fluorescence of I and displace the
maximum of intensities of fluorescence I in more long wave area of the
spectrum that, probably, is due to formation of complex I with Cu(II).
Dependencies of intensities of fluorescence on pH (I=f(pH)) for
solution I and I-Cu(II) are presented on figures 3. It is established that
maximum quenching of fluorescence of the solution I by Cu(II) exists at
pH=6.0. This results can be used for florescent determination Cu(II) in
solution with I.
The dependency of intensities of fluorescence of the solution ICu(II) on concentration Cu(II) in solution are presented on figures 4. It
is established that the range of Cu(II) determination with I by
fluorescent method is from 0.25 mg/l to 2.5 ml/l. The ranges of Cu(II)
determination with I and II are coincide.
0,6
1
2,6
0,5
2
0,4
I
2,4
I
0,3
0,2
2,0
3
0,1
2,2
1,8
0,0
0
2
4
6
8
10
0,0
pH
0,5
1,0
1,5
2,0
2,5
C(Cu(II))
Fig. 3. I=f(pH) for solutions:
1 – II=f(pH), CI = 4.17·10-4М;
2 – II-Сu(II) =f(pH),Cсu(II) =1.0·10-4М;
3 -∆I=II – II-Сu(II) =f(pH).
l=1.00 cm, λex=250 nm, λreg =370 nm,
«average» sensitivity level.
Fig. 4. I=f(CCu(II)),С (I)=4.0·10-5М,
рН=6.0, l=1.00 cm, λex=255 nm, λreg
=370 nm, «average» sensitivity level.
This work was performed with financial support of Russian
Foundation for Basic Research (grant № 06-03-32981).
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