A Novel Ferrocene-DOPPV Conjugated Copolymer Camila S. Gonc ¸alves, 1 Jose´P. Serbena, 2 Ivo A. Hu ¨ mmelgen, 2 Jonas Gruber * 1 Summary: The synthesis of a conjugated copolymer, poly[(1,1 0 -ferrocenylenevinylene)- co-(2,5-di-n-octyloxy)-p-phenylenevinylene] (PFV-DOPPV) via McMurry coupling of 1,1 0 -ferrocenedialdehyde and 2,5-di-n-octyloxybenzene-1,4-dialdehyde is reported. PFV- DOPPV was fully characterized by 1 H NMR, FTIR, FT-Raman, UV-VIS, cyclic voltammetry, size exclusion chromatography (SEC), inductively coupled plasma - optical emission spectrometry (ICP-OES), thermogravimetry (TG) and differential scanning calorimetry (DSC). The ionization potential, band-gap energy, electron affinity, HOMO and LUMO levels could be estimated. Electrical measurements in a sandwich device exposed to magnetic fields revealed magnetoresistance. Keywords: conducting polymers; copolymerization; ferrocene; magnetoresistance; McMurry coupling Introduction The incorporation of organometallic units to a conjugated polymer may greatly affect its properties. [1] In the last decade, the interest in organometallic polymers has increased owing their application in light emitting diodes, [2] molecular magnets, [3] gas sensors, [4] photovoltaic devices, [5] besi- des in many others. With 18 electrons in the valence shell, ferrocene is the most stable member of the metallocenes, [6,7] being not sensitive to air and humidity. However, it may be easily oxidized electrochemically or by weak oxidants. Ferrocene is an electron- rich arene and reacts up to 100 times faster than benzene in Friedel-Crafts reactions. [7] Among many kinds of conjugated poly- mers, poly( p-phenylenevinylene) (PPV) and its derivatives, [8] formed essentially by aro- matic moieties attached to vinylenic units, are highly attractive because of their success- ful application in electroluminescent devices [9] and, more recently, in solar cells, [10] magnetic transistors [11,12] and electronic noses. [13–15] In this communication, we report the synthesis and characterization of a novel copolymer of the poly( p-phenylenevinylene) (PPV) family, formed by 1,1 0 - ferrocenyle- nevinylene units alternated with 2,5-di- n- octyloxy-p-phenylenevinylene units, i.e., poly[(1,1 0 -ferrocenylenevinylene)-co-(2,5-di- n-octyloxy)-p-phenylenevinylene] (PFV- DOPPV). Experimental Part General Methods For the cyclic voltammetry (CV) experi- ment, commercial acetonitrile (MeCN) was purified and dried as described else- where. [16] All other commercially available materials were used as received. 1 H NMR FT spectra (200 MHz) were recorded on a Bruker AC-200 spectrometer using deuteriated chloroform/TMS (Aldrich) as solvent/reference. FTIR spectra were recorded as a KBr disc, on a Perkin-Elmer 1750 series grating. Only major or impor- tant absorptions are given. FT-Raman spectrum was recorded in a Bruker spectro- meter, model FTS100/S, equipped with a Nd-YAG continuous laser (1064 nm and Macromol. Symp. 2006, 245–246, 22–26 DOI: 10.1002/masy.200651304 22 1 Instituto de Quı´mica, Universidade de Sa ˜o Paulo - Av. Lineu Prestes, 748 - Cidade Universita ´ ria, 05508-900 - Sa ˜o Paulo, SP - Brazil E-mail: jogruber@iq.usp.br 2 Universidade Federal do Parana ´, Setor de Cie ˆ ncias Exatas, Departamento de Fı´sica - Centro Polite ´ cnico, 81531-990 - Curitiba, PR - Brazil Copyright ß 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim