Oligo-thiophene tethered 1,10-phenanthroline as N-chelating moiety. Electrochemical and optical characterization of the p-conjugated molecule and of the relevant conducting polymer and metallopolymers Paola Manca, Serafino Gladiali, Daniela Cozzula 1 , Antonio Zucca, Gavino Sanna, Nadia Spano, Maria I. Pilo * Dipartimento di Chimica e Farmacia, Universit a di Sassari, Via Vienna 2, 07100 Sassari, Italy article info Article history: Received 30 June 2014 Received in revised form 28 October 2014 Accepted 1 November 2014 Available online xxx Keywords: Conducting polymers Phenanthroline Ru(II) complex abstract The synthesis and characterization of a new highly conjugated molecule, 4-(2,2':5 0 ,2 00 -terthien-3'-ethy- nyl)-1,10-phenanthroline (TAF4) is reported. The newcompound features an expanded p-conjugation as compared with the analogue 2,2 0 :6 0 ,2 00 -terpyridine derivative (4'-(2,2':5 0 ,2 00 -terthien-3'-ethynyl)- 2,2':6 0 ,2 00 -terpyridine) we have recently reported. The electrochemical polymerization of TAF4 allows to obtain the corresponding conducting polymer PTAF4. Electrochemical and spectroscopic characterization were performed on both the original tether TAF4 and the polymer, and the results are compared with related structures bearing different spacers and nitrogen substituents. PTAF4 shows a remarkable lowering of band gap value that is consequent on the nature both of the spacer and of the substituent on the terthiophene fragment. Furthermore, the synthesis and characterization of the Ru(II) complex, [Ru(TAF4) 3 ][PF 6 ] 2 , and of the corresponding metallopolymers, are reported. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Conjugated materials have attracted particular attention in the past few decades, because of their properties and practical appli- cations. Interest is motivated by their suitability in photophysical, optical and electronic devices. In particular polythiophenes (PT) are an important class of conducting polymers (CPs) because of their structural versatility and thermal stability of both neutral and doped forms [1]. For this reason synthesis, electrochemical and spectroscopic properties and electronic transport mechanism of oligo- and polythiophenes have been widely studied and many structureeproperty relationships have been elucidated up to date. The key of their versatility lies in the possibility of introducing different substituents on the heterocyclic ring, the nature and the position of the functionalization being tools for a high tunability. In the last decades, many efforts have been devoted to the derivati- zation of thiophene in 3 or 4 position, with a wide variety of aryl substituents [2e5]. Furthermore, p-conjugated polymers containing chelating li- gands are a subject of high interest, because they allow the elec- tronic, optical and catalytic properties of metal complexes to be coupled with non-linear optical properties, electronic conductivity, luminescence and processability of conducting polymers [6,7]. In particular polypyridine complexes of ruthenium(II) received the greatest attention by groups working on photoinduced electron and energy transfer [8], because [Ru(bipy) 3 ] 2þ (bipy ¼ 2,2 0 -bipyr- idine) is the best known and most studied photoluminescent transition-metal complex [9]. An obvious alternative to bipyridine- derivatives is 1,10-phenanthroline (phen), and the photochemistry of copper(I) bis(phenanthroline) complexes has been investigated [10] to make them suitable for practical applications such as light harvesting for photovoltaic cells. Since phen is a ligand with a p-conjugated condensed structure, it looks as an excellent candidate for the inclusion in conducting polymers. Its rigid structure provides for the enhanced stability of * Corresponding author. Tel.: þ39 079 229578; fax: þ39 079 229559. E-mail address: mpilo@uniss.it (M.I. Pilo). 1 Present address: CAT Catalytic Center ITMC, RWTH Aachen University, Wor- ringerweg 1, 52074 Aachen, Germany. Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer http://dx.doi.org/10.1016/j.polymer.2014.11.004 0032-3861/© 2014 Elsevier Ltd. All rights reserved. Polymer xxx (2014) 1e8 Please cite this article inpress as: Manca P, et al., Oligo-thiophene tethered 1,10-phenanthroline as N-chelating moiety. Electrochemical and optical characterization of the p-conjugated molecule and of the relevant conducting polymer and metallopolymers, Polymer (2014), http:// dx.doi.org/10.1016/j.polymer.2014.11.004