3,6-Linked 9-Alkyl-9H-carbazole Main-Chain Polymers: Preparation and Properties AHMED IRAQI, ISAO WATARU University of Sheffield, Department of Chemistry, Sheffield S3 7HF, UK Received 28 May 2004; accepted 16 July 2004 DOI: 10.1002/pola.20420 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: An investigation into the preparation of poly(9-alkyl-9H-carbazole-3,6- diyl)s with palladium catalyzed cross-coupling reactions of 3-halo-6-halomagnesio-9- alkyl-9H-carbazoles, generated in situ from their corresponding 3,6-diiodo- and 3,6- dibromo-derivatives was undertaken. Monomers with a range of alkyl group substitu- ents with different steric requirements were investigated and their effects on the polymerization were studied. The effects of the nature of halogen substituents on the polymerization reaction were also investigated. Structural analysis of the polymers revealed exclusive 3,6-linkage between consecutive carbazole repeat units on the poly- mer chains. The physical properties of these polymers were investigated with spectro- scopic, thermal gravimetric analysis, and electrochemical studies. © 2004 Wiley Periodi- cals, Inc. J Polym Sci Part A: Polym Chem 42: 6041– 6051, 2004 Keywords: catalysis; conjugated polymers; light-emitting diodes INTRODUCTION There has been a great deal of interest recently in the development of organic-based materials for ap- plication in the electronics industry. Poly(vinylcar- bazole) has been used in many semiconducting ap- plications. Studies have shown that this material could be used in electroluminescent devices as a hole-transporting material, 1 a light emitting mate- rial, 2 or a wide bandgap energy transfer donor. 3– 6 Until recently, carbazole main-chain linked poly- mers have, however, received little attention in the literature despite the potential benefits that such polymers could afford in comparison with the con- ventional poly(vinylcarbazole). Until recently, the nickel-catalyzed dehalogenative reductive polymer- ization of 3,6-dihalo-9H-carbazole derivatives with electrochemical routes 7 was one of the main syn- thetic routes to these materials. A recent study in the literature 8 has shown that these polymers are also accessible with nickel(0) reagent based on the Yamamoto coupling reaction. In a recent communication, 9 we have reported a new synthetic route to these materials with palladium catalyzed cross-coupling polymeriza- tion methodology. In this article we present our findings on the preparation of a range of poly(9- alkyl-9H-carbazole-3,6-diyl)s with a range of al- kyl groups of different steric requirements and report our results on the use of monomers with different halogen groups and the effect on the polymerization reaction. We also report spectro- scopic, electrochemical, and thermal gravimetric studies on these polymers. EXPERIMENTAL Materials 3-Bromomethylheptane, tetrabutylammonium hydrogen sulfate, 1-bromododecane, 1-bromo- hexadecane, (2,2' -bipyridine)-dichloropalladi- um(II), and tetrabutylammonium tetrafluorobo- rate (TBABF 4 ) were obtained from Sigma- Correspondence to: A. Iraqi (E-mail: a.iraqi@ sheffield.ac.uk) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 42, 6041– 6051 (2004) © 2004 Wiley Periodicals, Inc. 6041