4th EucheMs chemistry congress

Poster Session 2
s1156
chem. Listy 106, s257–s1425 (2012)
Poster session 2 - Analytical Chemistry
P - 0 5 8 8
voLtAMMetriC deterMinAtion of
5-nitroBenziMidAzoLe At A BiSMuth
fiLM-Modified GoLd eLeCtrode
v. vySKoCiL 1 , B. ChLAdKovA 1 , d. deyLovA 1 ,
J. BAreK 1
1 Charles University in Prague (Faculty of Science), Department
of Analytical Chemistry, Prague, Czech Republic
Bismuth film electrodes have become an attractive new
subject of electroanalytical research as a potential replacement for
mercury electrodes. In this work, the voltammetric behavior of
the genotoxic compound 5-nitrobenzimidazole was investigated
using direct current voltammetry (DCV) and differential pulse
voltammetry (DPV) at a bismuth film-modified gold electrode
(BiF-AuE). The bismuth film was deposited ex situ at a constant
potential of –1.2 V (vs. Ag/AgCl (3 mol L –1KCl)) for 300 s in a
plating solution (1.0 g L –1 Bi(III) solution in 0.1 mol L –1 acetate
buffer of pH 4.5) under stirring. The optimum conditions for the
determination of 5-nitrobenzimidazole in the concentration range
from 1 to 100 µmol L –1 were found in the medium of
Britton–Robinson buffer of pH 9.0; the limits of quantification
(L s) were found to be 0.54 µmol L Q –1 (for DCV) and 2.0 µmol L –1
(for DPV). An attempt to increase the sensitivity using adsorptive
stripping voltammetry at the BiF-AuE was not successful. The
practical applicability of the newly developed methodology was
verified for the direct determination of 5-nitrobenzimidazole in
drinking and river water model samples, with L s≈10 Q -6 mol L-1 .
Acknowledgement: This research was financially supported by
The Ministry of Education, Youth and Sports of the Czech
Republic (Project MSM0021620857), by the Charles University
in Prague (Projects UNCE 2012/44 and SVV 2012-265201) and
by The Grant Agency of the Czech Republic (Project
P206/12/G151).
Keywords: Analytical methods; Electrochemistry;
Voltammetry; Bismuth; Thin films;
4 th EucheMs chemistry congress
P - 0 5 8 9
fuLLy deLoCALized
(ethynyL)(vinyL)PhenyLene BridGed
trirutheniuM CoMPLexeS in uP to five
different oxidAtion StAteS
e. wuttKe 1
1 University of Konstanz, Chemistry, Konstanz, Germany
Within the field of organometallic mixed-valent chemistry,
1,4-diethynylphenylene has gained particular popularity as a
bridging ligand because of the ready availability of the parent
alkyne, its good ability to electronically couple the bridged sites
and the stability it conveys to the oxidized forms. At the same
time, the 1,4-diethynylphenylene ligand has turned out as an
excellent example of Janus-headed behaviour with respect to
Jorgensens original definition of a non-innocent ligand. [1]
Spectroscopic and cyclovoltammetric investigations on the
triruthenium complex [(dppe) 2 Ru{-C=C-1,4-C 6 H 4 -CH=CH-
-RuCl(CO)(P i Pr 3 ) 2 } 2 ] n+ suggest that this carbon-rich complex is
an intriguing case of extended metal-organic p-systems exhibiting
complete electron delocalization over three redox-active subunits
in five well-separated redox states (n = 0-4). The carbon rich
ethynyl(vinyl)phenylene bridges are non-innocent redox-active
ligands which actively participate in every redox process. Given
the rather strong interest in understanding molecular wires [2] , it
seemed worthwhile to add gold-binding functional groups on the
terminal moieties in order to gain valuable insight into the
structure-property relationships of molecular wires with holeconducting
properties and low turn-on voltage. [3]
Herein we report the synthesis and our findings on the
bis(ethynylvinyl)phenylene bridged trinuclear complexestrans-
-[{Ru(dppe) }{-C=C-1,4-C H -CH=CH-RuCl (CO)(P 2 6 4 iPr ) } ], 3 2 2
trans -[{Ru(dppe) }{-C=C-1,4-C H -2,5-(OMe) -
2 6 2 2
- C H = C H -RuCl(CO) (P iPr ) } ] and its corresponding
3 2 2
derivative trans-[{Ru(dppe) }{-C=C-1,4-C H -CH=CH-Ru(η 2 6 4 2- -O CC H SAc)(CO)(P 2 6 4 iPr ) } ] with respect to charge and spin
3 2 2
delocalization. The terminal 4-mercaptobenzoate ligands of
trans-[{Ru(dppe) }{-C=C-1,4-C H -CH=CH-Ru(η 2 6 4 2- -O CC H SAc)(CO)(P 2 6 4 iPr ) } ] bind to gold electrodes
3 2 2
and should allow for measuring molecular conductivities.
references:
1. C. K. Jorgensen, Coord. Chem. Rev., 1966, 1, 164-178.
2. D. Astruc Electron-Transfer Processes in Transition Metal
Chemistry; VCH: New York, 1995.
3. E. Wuttke, F. Pevny, Y.-M. Hervault, L. Norel,
M. Drescher, R. Winter and S. Rigaut
Inorganic Chemistry 2012, 51, 1902.
Keywords: cyclovoltammetry; spectroelectrochemistry;
molecular wires; organometallic mixed-valent chemistry;
Ruthenium;
AUGUst 26–30, 2012, PrAGUE, cZEcH rEPUbLIc