In situ EPR and UV-vis spectroelectrochemistry of hole-transporting organic substrates.
A newly developed in situ electron paramagnetic resonance (EPR)/ultraviolet-visible (UV-vis) spectroelectrochemical cell equipped with a laminated indium-tin oxide (ITO) working electrode was used in the investigation of various organic substrates which are potential hole-transporting materials. The experiment demonstrated the possibility of using such a technique for examining redox behavior of conducting polymers (polypyrrole, PPy), oligomers (thiophene dimmer and quarterthiophene) and bis-anilines (N,N,N',N'-tetraphenylbenzidine, TPB). All investigated structures formed stable paramagnetic intermediates in the first oxidation step characterised with UV-vis spectra in the region 400-600 nm. In the second oxidation step EPR-silent di-cationic structures are formed with broad vis bands in the region 600-1000 nm. The measurement of the reference UV-vis spectra direct in the EPR cavity was possible using a specially-constructed non-contacted ITO plate in the spectroelectrochemical cell in the case of polypyrrole.
Rapta
P
P
Slovak Technical University, Bratislava, Slovak Republic. rapta@cvt.stuba.sk
Fáber
R
R
Dunsch
L
L
Neudeck
A
A
Nuyken
O
O
D001560:Benzidines / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation*; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry; D013053:Spectrophotometry / Q000295:instrumentation*; D013056:Spectrophotometry, Ultraviolet / Q000295:instrumentation*; D013876:Thiophenes / Q000737:chemistry
D001560:Benzidines; D011108:Polymers; D011758:Pyrroles; D013876:Thiophenes; C003925:tetraphenylbenzidine; C067635:polypyrrole