Absorption and fluorescence emission attributes of a fluorescent
dye: 2,3,5,6-tetracyano-p-hydroquinone.
Muhammad Zahida,b*, Günter Gramppb, Asim Manshab,c, Ijaz Ahamad Bhattia, Sadia Asimb,c
a
Department of Chemistry & Biochemistry, University of Agriculture Faisalabad, Pakistan.
b
Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz/Austria
c
Department of Chemistry, GC University Faisalabad, Pakistan
Supporting information (Supplementary data)
1.
Absorption spectra of TCHQ in various solvents
1.1. TCHQ in Ether
In low polarity solvents like ethers, the absorption spectra showed only one peak at 398 nm for
different concentration as shown in the inset of Fig. S-1.
Decrease in absorption intensity on dilution
3
0.20
Absorption spectra of TCHQ at very low conc.
in diethylether have only one peak 398nm
2
Absorbance
Absorbance
0.15
0.10
dilute solution
0.05
1
0.00
300
400
500
600
Wavelength (nm)
0
300
400
500
600
Wavelength (nm)
Fig. S-1: Absorption Spectra of TCHQ in diethyl ether for different concentrations.
1
1.2.
TCHQ in acetone and acetonitrile
Two peaks were observed in the range of 300 to 600 nm for moderately polar solvents like
acetone (Fig. S-2) and acetonitrile (Fig. S-3). The first peak is in the range of 390-400 nm and
the second peak is around 505 nm.
Decrease in absorption intensity on dilution
0.6
0.09
Absorbance
Absorbance
Most dilute solution of TCHQ
0.4
0.06
0.03
0.00
300
0.2
400
500
600
wavelength (nm)
0.0
300
350
400
450
500
wavelength (nm)
550
600
650
Fig. S-2: Absorption spectra of TCHQ in acetone for different concentrations.
Two peaks were observed at 392 nm and 502 nm for various concentrations of TCHQ in
acetonitrile as shown in Fig. S-3. This non-linear decrease in the absorption intensity at two
different wavelengths (392 nm and 502 nm) has been shown clearly in the Fig. S-4 (a) and Fig.
S-4 (b).
2
-5
Conc. 10 M
18.2
11.3
7.7
3.9
3.5
3.0
2.5
2.2
2.0
1.7
1.4
1.0
0.7
0.4
0.2
Absorbance
1.6
1.2
0.8
0.15
-5
Absorbance
2.0
Conc. 10 M
2.0
1.7
1.4
1.0
0.7
0.4
0.2
0.10
0.05
0.00
300
400
500
600
Wavelength (nm)
0.4
0.0
300
400
500
600
Wavelength (nm)
Fig. S-3: Absorption spectra of TCHQ in acetonitrile at different concentrations.
2.0
(b)
Absorbance (normalized)
(a)
Absorbance
1.6
1.2
0.8
392 nm
502 nm
0.4
0.9
0.6
0.3
392 nm
502 nm
0.0
0.0
0
3
6
9
12
15
18
-5
Conc. of TCHQ in MeCN (10 M)
0
4
8
12
16
-5
Conc. of TCHQ in MeCN (10 M)
Fig. S-4: (a) Absorbance and (b) normalized absorbance of TCHQ in acetonitrile (MeCN) for different
concentrations at 392 nm and 502 nm.
1.3.
TCHQ in water and ethanol
Two peaks of TCHQ were observed in water for most of the concentrations except very dilute
ones (conc. < 1x10-5 M) as shown in Fig. S-5. Signal intensity at 460 nm has been decreased
3
rapidly as compared to the peak at 520 nm, with the decrease in concentration of the TCHQ in
H2O as shown in Fig. S-6.
Absorbance
Concentration
-5
16.6 10 M
-5
5.6 10 M
-5
2.8 10 M
-5
1.8 10 M
-5
0.9 10 M
-5
0.5 10 M
2
Absorbance
0.3
3
0.2
Concentration
-5
2.8 10 M
-5
0.9 10 M
-5
0.510 M
0.1
0.0
300
400
500
600
Wavenumber (nm)
1
0
300
400
500
600
Wavenumber (nm)
Fig. S-5: Absorption Spectra of TCHQ in H2O at different concentrations.
(a)
1.0
Absorbance
Absorbance (normalized)
1.2
0.8
0.6
0.4
440 nm
540 nm
0.2
0.0
0
3
6
9
(b)
1.0
0.8
0.6
0.4
440 nm
540 nm
0.2
0.0
12
15
-5
Conc. of TCHQ in H2O (10 M)
18
0
3
6
9
12
15
18
-5
Conc. of TCHQ in H2O (10 M)
Fig. S-6: (a) Absorbance and (b) normalized absorbance of TCHQ in H2O for different concentrations at 440
nm and 540 nm.
Absorption spectra of TCHQ after adding a small amount of water (less than 2%) into the dilute
solution of TCHQ (3 x 10-5 M) in absolute ethanol is shown in Fig. S-7.
4
0.5
Absorbance
0.4
0.3
Absolute ethanoll
EtOH + H2O (<2%)
0.2
0.1
0.0
300
400
500
600
700
Wavelength (nm)
Fig. S-7: Absorption spectra of TCHQ in absolute ethanol and ethanol containing water (< 2%).
2. Fluorescence emission spectra of TCHQ in different solvents
excited at various wavelengths
(a) Absorption spectrum of TCHQ in diethylether
(b) Fluorescence spectra of TCHQ in diethylether
excited at 390 nm, 430 nm & 460 nm.
0.8
Absorbace
8
2x10
0.4
0.2
(exc= 390 nm)
0.0
8
(exc= 430 nm)
1x10
(exc= 460 nm)
0
400
450
500
550
600
Wavelength (nm)
650
700
Normalized fluorescence intensity
Fluorescence (counts)
0.6
750
1.0
300
400
500
wavelength (nm)
600
700
(c) Normalized fluorescence spectra of TCHQ in
diethylether excited at 390 nm, 430 nm & 460 nm
0.8
(exc= 390 nm)
0.6
(exc= 430 nm)
0.4
(exc= 460 nm)
0.2
0.0
400
500
600
700
wavelength (nm)
Fig. S-8. (a) Absorption, (b) fluorescence and (c) normalized fluorescence spectra of TCHQ in diethylether.
The excitation wavelengths are 390 nm, 430 nm and 460 nm.
5
0.4
(a) Absorption spectrum of TCHQ in n-butyl ether
Absorbace
8
1.5x10
0.2
300
8
1.0x10
exc= 390 nm
1.2
Normalized fluorescence intensity
Fluorescence intensity (counts)
(b) Fluorescence spectra of TCHQ in n-butylether
excited at 390 nm & 460 nm wavelength
7
5.0x10
exc= 460 nm
0.0
400
500
600
700
Wavelength (nm)
400
500
Wavelength (nm)
600
700
(c) Normalized fluorescence spectra of TCHQ in nbutylether excited at 390 nm & 460 nm wavelength
1.0
0.8
exc= 390 nm
0.6
exc= 460 nm
0.4
0.2
0.0
400
500
600
Wavelength (nm)
700
Fig. S-9. (a) Absorption, (b) fluorescence and (c) normalized fluorescence spectra of TCHQ in nThe excitation wavelengths are 390 nm and 460 nm.
butylether.
(b) Fluorescence Spectrum of TCHQ
in acetone excited at 515 nm.
0.3
(a) Absorption spectrum of TCHQ in acetone
8
1.0x10
Absorbace
Fluorescence Intensity (counts)
8
1.5x10
7
5.0x10
0.2
0.1
400
0.0
500
550
600
650
700
500
600
wavelength (nm)
700
750
wavelength (nm)
Fig. S-10. (a) Absorption, (b) fluorescence spectra of TCHQ in acetone excited at 515 nm.
6
1.0
(b) Fluorescence spectra of TCHQ in Acetonitrile
excited at 390 nm & 515 nm wavelength
0.8
8
Absorbace
Fluorescence Intensity
3x10
8
0.6
0.4
0.2
exc= 390 nm
2x10
(a) Absorption Spectrum of TCHQ in Acetonitrile
0.0
300
400
500
600
700
Wavelength (nm)
exc= 515 nm
1.2
Normalized fluorescence
8
1x10
0
400
500
600
700
(c) Normalized fluorescence spectra of TCHQ in
acetonitrile excited at 390 nm & 515 nm wavelength
0.9
exc= 390 nm
0.6
exc= 515 nm
0.3
0.0
300
Wavelength (nm)
400
500
600
700
Wavelength (nm)
800
Fig. S-11. (a) Absorption, (b) fluorescence and (c) normalized fluorescence spectra of TCHQ in acetonitrile.
The excitation wavelengths are 390 nm and 515 nm.
0.20
(b) Fluorescence spectra of TCHQ in ethanol + water (<2%)
excited at 460 nm ,515 nm & 550 nm wavelength
Absorbace
7
7
0.15
0.10
5x10
exc= 460 nm
7
0.05
4x10
300
400
exc= 515 nm
7
3x10
exc= 550 nm
7
2x10
1.0
7
1x10
0
450
500
550
600
650
wavelength (nm)
700
500
600
700
wavelength (nm)
750
800
Normalized fluorescence intensity
Fluorescence intensity (counts)
6x10
(a) Absorption spectrum of TCHQ in
ethanol + water (<2%)
(c) Normalized fluorescence spectra of TCHQ in ethanol + water
(<2%) excited at 460 nm, 515 nm & 550 nm wavelength
exc= 460 nm
0.8
exc= 515 nm
0.6
exc= 550 nm
0.4
0.2
0.0
450
500
550
600
650
700
750
800
wavelength (nm)
Fig. S-12. (a) Absorption, (b) fluorescence and (c) normalized fluorescence spectra of TCHQ in ethanol +
water (< 2 %). The excitation wavelengths are 460 nm, 515 nm and 550 nm.
7
(b) Fluorescence Spectra of TCHQ in DMSO
excited at 515 nm, 570 nm & 670 nm wavelength
Absorbace
Fluorescence intensity (counts)
0.3
7
9.0x10
(a) Absorption spectrum of TCHQ in DMSO
0.2
0.1
exc= 515 nm
0.0
7
6.0x10
7
3.0x10
1.2
Normalized fluorescence intensity
exc= 570 nm
exc= 670 nm
0.0
500
550
600
650
700
Wavelength (nm)
750
800
300
400
500
600
Wavelength (nm)
700
800
(c) Normalized fluorescence spectra of TCHQ in DMSO
excited at 515 nm, 570 nm & 670 nm wavelength
1.0
0.8
exc= 570 nm
exc= 670 nm
exc= 515 nm
0.6
0.4
0.2
0.0
500
550
600
650
700
750
800
Wavelength (nm)
Fig. S-13. (a) Absorpti*on, (b) fluorescence and (c) normalized fluorescence spectra of TCHQ in DMSO. The
excitation wavelengths are 515 nm, 570 nm and 670 nm.
8