**2.2 Preparation of 2,5-di-(2-thienyl)-pyrrole (SNS)**

2,5-di-(2-thienyl)-pyrrole (SNS) was prepared by the method described by Wynberg and Metselaar [Wynberg & Metselaar, 1984]. The yield was improved by refluxing the solution of the intermediate 1,4-di-(-2-thienyl)-1,4-butanedione (3 *g*) with ammonium acetate (40.3 *g*), glacial acetic acid (120 *ml*) and acetic anhydride (24 *ml*) overnight under a nitrogen atmosphere. The reaction mixture was then poured into 250 *ml* of distilled water and the resulting dark-green solid was chromatographed over a silica gel column with dichloromethane: hexane (3:2) elution to give SNS with 75% yield, as pale yellow crystals of melting point 82-83 ºC.

IR(KBr): 3490 cm-1 (N-H); 1H NMR(CDCl3): δ: 6.2(2H,d), 6.8(6H,m), 8.0(1H,s).

#### **2.3 Electropolymerization method and conductivity measurements**

The electropolymerization was carried out using digital potentiostate/galvanostate (Autolab PGSTAT 30). A glassy carbon (GC) disk (2 *mm* diameter) as working electrode, a platinum wire as a counter electrode and Ag/AgCl as a reference electrode were used. Acetonitrile was distilled over P2O5 and lithium perchlorate was used as an electrolyte in 0.1 *M* concentration. The electropolymerization of pyrrole (0.5 *ml*, 7.4 *mmole*) and SNS (16 *mg*, 0.074 *mmole*) in 0.1 *M* LiClO4/acetonitrile electrolyte were performed separately in two different potential ranges vs. Ag/AgCl at the scan rate of 50 *mV.s-1*. Similar conditions were adopted for the electropolymerization of pyrrole in the presence of SNS (7.4 *mmole*: 0.074 *mmole*). In the study of the cyclic voltammetry experiment of electron transfer, 1 mM ferro/ferricyanide in the 1 *M* H2SO4 media at 50 *mV.s-1* scan rate was used.

For the EIS measurements, the AC frequency range extended from 100 *kHz* to 10 *mHz*, a 10 *mV* peak-to-peak sine wave was as the excitation signal. Both real and imaginary components of the EIS in the complex plane were analyzed using the Zview(II) software to estimate the parameters of the equivalent electrical circuit. A computer-controlled potentiostate (PARSTATE 2263 EG&G) was used for EIS measurements.
