tailieunhanh - Study on the redox property of electroactive poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy- 3-acetic acid-1,4-naphthoquinone) thin film by in-situ raman spectroscopy

A new functionalized conducting poly(5-hydroxy-1,4-naphthoquinone-co-5-hydroxy-3-acetic acid-1,4-naphthoquinone) with electroactive quinone group was studied by in situ Raman spectroscopy. The Raman results confirmed a good reversible transformation between two structures: quinoid and hydroquinoid ones during reduction-oxidation processes. | Journal of Chemistry Vol. 43 1 P. 100 -104 2005 STUDY ON THE REDOX PROPERTY OF ELECTROACTIVE POLY 5-HYDROXY-1 4-NAPHTHOQUINONE-CO-5-HYDROXY-3-ACETIC ACID-1 4-NAPHTHOQUINONE THIN FILM BY IN-SITU RAMAN SPECTROSCOPY Received TRAN DAI LAM Faculty of Chemical Technology Hanoi University of Technology SUMMARY A new functionalized conducting poly 5-hydroxy-1 4-naphthoquinone-co-5-hydroxy-3-acetic acid-1 4-naphthoquinone with electroactive quinone group was studied by in situ Raman spectroscopy. The Raman results confirmed a good reversible transformation between two structures quinoid and hydroquinoid ones during reduction-oxidation processes. I - INTRODUCTION Poly 5-hydroxy-1 4-naphthoquinone-co-5-hydroxy-3-acetic acid- 1 4-naphthoquinone films poly JUG-co-JUGA were prepared by electropolymerization in organic medium Acetonitrile LiClO4 . Data from XPS IR ex situ IR in situ and theoretical calculations of frontier orbitals indicate that the structure of copolymer is composed alternatively of furan and naphthylene rings. Poly JUG-co-JUGA films show reversible well-defined redox system of quinone group in both organic and aqueous acid as well as in neutral aqueous solutions PBS pH . Especially the quinone electroactivity in neutral aqueous solution was crucial property allowing this polymer to be used as electro-chemically internal marker for direct biological detection in biosensors 1 . The redox behavior of quinone group in organic medium is normally investigated by IR in situ MIRFTIRS 2 . In this paper in situ Raman spectroscopy was used to study this redox system in neutral aqueous solution. The Raman method presents compared to method MIRFTIRS the advantage of being able to work 100 in situ in aqueous medium under favorable conditions the Raman diffusion of water is very weak . Furthermore contrary to MIRFTIRS Raman spectroscopy does not require any specific preparation of electrochemical cell as well as the sample the working electrode is standard