Universität Siegen, Organische Chemie I,
Adolf-Reichwein-Str. 2, D-57068 Siegen,
Tel: +49 271 740 4340
e-mail: lin@chemie.uni-siegen.de
4,7-Diazacrown Ether Ruthenium tris-Phenanthroline:
an All-Rounder Among Metal Ion Chemosensors
H.-W. Lin, E. Thiel, A. J. Meixner and M. Schmittel
Introduction
Metal ion sensors play an important role in detection and quantification of metal ions in many fields of application.1 Herein, we present a versatile
chemosensor based on the azacrown ether-containing tris-phenanthroline ruthenium complex 1.2 It showed diverse response to various metal ions (Na+,
K+, Ca2+, Ba2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Hg2+ and Pb2+ etc.) by a number of spectroscopic methods.
I Complex 1 used as a fluorescence chemosensor for Pb2+
and Cu2+
Synthesis and general description
O
O
O
400
N
O
N
O
O
reflux, 1 d
Ru
+
O
N
Cl
acetone,
EtOH
N
Cl
1
2
none
2+
10 eq. Ba
2+
10 eq. Cu
2+
10 eq. Pb
300
200
100
0
O
500
600
700
400
300
200
100
2,4
10,0
8,0
5,0
3,0
2,0
1,5
1,0
0,8
0,6
0,4
0,2
0,2
0
2,0
I/I0
N
Fluorescence intensity (a.u.)
O
Fluorescence intensity (a.u.)
N
O
1,2
0,8
600
O
O
O
O
ECL
N
Ru
2+
N
N
Cu
Hg
2+
O
2
1
N
O
O
O
2+
Titration curve of 1 (10 μM) in ACN with
various amounts of Cu2+ addition.
(excitation at 429 nm)
Stern-Volmer plots of 1 with various
amount of Cu2+ addition. (insert)
O
500
2000 A
ECL intensity (a.u.)
1500
ECL intensity (a.u.)
ECL intensity ( a. u.)
ECL intensity (a. u.)
2+
Cu
3+
Cr
3+
2+
Fe , Ni
2+
Cd
2+
Zn
No one
+
Ag
2+
Co
1000
100
50
0,6
0,4
0,2
0,0
0
1
2
3
4
2+
equivalents of Cu
600
700
800
1500
1000
500
0
0
10
20
30
40
2+
[Hg ] /(micromol)
0,8
2000 B
1500
y=87.2x + 160
R=0.9899
E [V]
vs. Fc
1000
500
0
50
0
5
10
15
2+
[Hg ]/(micromol)
20
0,7
1000
500
E1/2
Epc
Epa
0,6
0
600
700
800
900
Wavelength(nm)
900
III Complex 1 used as an electrochemical chemosensor
for Pb2+or Ba2+
0
500
5
Wavelength (nm)
2000
1500
0,8
0
0,2
0,4
0,6
0,8
1,0
1,5
2,0
5,0
500
2000
2+
1,0
150
0
2+
II Complex 1 used as an electrochemiluminescence
(ECL) chemosensor for Hg2+
Hg
800
200
Electrochemistry
Pb , Ba
10
Titration curve of 1 (10 μM) in ACN with
various amounts of Pb2+ addition.
(excitation at 429 nm)
Stern-Volmer plots of complex (I) with
various amount of Pb2+ addition. (insert)
Fluorescence intensity (a.u.)
N
700
I/I0
N
2+
Pb , Fluorescence
Fluorescence spectra of 1 (10 μM) in ACN
with 10 eq. of different metal ions addition.
All of the other metal ions, such as Na+, K+,
Ca2+, Cr3+,Co2+, Ni2+, Zn2+, Cd2+ and Hg2+
only have very lightly effect. (excitation at
429 nm)
2
4
6
8
2+
equivalents of Pb
Wavelength (nm)
Wavelength (nm)
O
0
0
500
800
1,6
500
600
700
800
900
OX
Wavelength (nm)
0,5
ECL spectrum of 1 (10 μM) in tetrabutylammonium phosphate buffer (0.1
M) solution (pH 7.0) in the presence of
different metal ions (50 μM), showing
nearly no response to some other metal
ions, such as Na+, K+, Ca2+, Ba2+, Pb2+.
ECL intensity of 1 (10 μM) vs [Hg2+] in
tetrabutylammonium phosphate buffer (0.1
M) solution ( pH 7.0). [Hg2+] are 0, 5, 15, 20
μM (from bottom to top).
Titration curve of [Hg2+] from 0 to 50 μM
(insert A)
Titration and fitting curve of [Hg2+] from 0
to 20 μM. (insert B)
ECL intensity (a. u.)
2000
1500
1000
500
0
No
1 Hg
one
2 2+
2+
4 2+
52+
62+
72+
8 2+
9 2+
102+
112+
2+
2+
142+
152+
3 Hg Hg Hg Hg Hg Hg Hg Hg Hg
12 Hg
13 Hg Cd
Hg
+
+
+
+
+
+
+
+
+
+
+
+
+
2+
2+
2+
2+
Co Ag+ Na+ K+ Ca2+ Ba 2+ Pb2+ Cr3+ Fe3+ Ni Cu Zn2+ Hg
ECL intensity change profile of 1 (10 μM) in
a mixture metal ions (Hg2+ and other metal
ions are 20 μM, respectively) in tetrabutylammonium phosphate buffer (0.1 M) solution
(pH 7.0).
Conclusions
A versatile all-rounder metal ion chemosensor was developed, showing
diverse metal ion selectivity depending on the detection method.
0
1
2
3
4
2+
equivalents of Ba
5
6
Electrochemistry responses of 1 with various
amounts of Ba2+ addition.
Redox potential of 1 without (left top) and with
0.5 eq. (left middle), 10 eq. (left bottom) of Ba2+
addition. The left reversible wave is 1,1´-dimethylferrocene internal standard.
Pb2+ shows very
responses as Ba2+.
similar
electrochemical
Acknowledgments
We are greatly indebted to the Deutsche Forschungsgemeinschaft for
financial support.
References:
1 a) A. P. de Silva, H. Q. N. Gunaratne, T. Gunnlaugsson, A. J. M. Huxley, C. P. McCoy, J. T. Rademacher, T. E. Rice, Chem. Rev. 1997, 97, 1515-1566; b) M. H. Keefe, K. D.
Benkstein, J. T. Huup, Coord. Chem. Rev. 2000, 205, 201-228.
2 a) M. Schmittel, H. Ammon, J. Chem. Soc., Chem. Commun. 1995, 687-688; b) M. Schmittel, H. Ammon, C. Wöhrle, Chem. Ber. 1995, 128, 845- 850.