## 2 Materials and Methods
H2O (20 mL) was added to the residue, the organic phase was extracted with diethyl ether (3 \(\times\) 30 mL) and washed with water (90 mL). Finally, the solution was treated with MgSO4 and filtered, and the solvent was evaporated under reduced pressure. The crude product was purified by column chromatography on silica, using petroleum ether/dichloromethane 9/1 as eluent, to give 2,2'.5',2''-terthiophene (2, 0.5612 g, 2.259 mmol, yield 95%). 1'H NMR (CD2 Cl2, ppm), \(\delta_{\text{H}}\): 7.29 (dd, 2H, H5 + H5-, 3) = 5.1 Hz, 4' = 1.0 Hz); 7.23 (dd, 2H, H3 + H3-, 3) = 3.6 Hz, 4' = 1.0 Hz); 7.14 (s, 2H, H3 + H4v); 7.07 (dd, 2H, H4 + H4v, 3) = 5.1 Hz, 4' = 3.6 Hz). _Synthesis of 5-bromo-2,2'.5',2''-terthiophene_ (**3**). NBS (0.3187 g, 1.790 mmol) was added drop by drop to a solution of terthiophene (2, 0.4922 g, 1.982 mmol) in DMF (6 mL). The additions were performed out of light, during 6 h, at -20 \({}^{\circ}\)C, under stirring. At the end of the additions, the reaction mixture was taken to room temperature, then the reaction was let to proceed further for 24 h. Finally, the mixture was poured into iced water (60 mL), and extraction with CH2 Cl2 was performed. The organic phase was washed with H2O, treated with MgSO4 and filtered, and the solvent was evaporated under reduced pressure. The crude product was crystallized with hexane to give **3** (0.5107 g, 1.560 mmol), with 79% yield. 1'H NMR (CD2 Cl2, ppm), \(\delta_{\text{H}}\): 7.30 (dd, 1H, H5-, 3) = 5.1 Hz, 4' = 1.0 Hz); 7.23 (dd, 1H, H3-, 3) = 3.6 Hz, 4' = 1.0 Hz); 7.13 (d, 1H, H4-, 3) = 3.8 Hz); 7.07 (dd, 1H, H4-, 3) = 5.1 Hz, 4' = 3.6 Hz); 7.04 (dd, 1H, H4-, 3) = 3.9 Hz); 6.98 (d, 1H, H3-, 3) = 3.9 Hz). _Synthesis of 5-(3-hydroxy-3-butyl-1-inyl)-)-)-2,2'.5',2''-terthiophene_ (**4**). 5-bromo-2,2'.5',2''-terthiophene_ (**3**), 0.2311 g, 0.707 mmol), [Pd(dppfCl2)] (0.0057 g, 0.007 mmol) and CuI (0.0042 g, 0.022 mmol) were dissolved in dispropylamine (5 mL), and 2-methyl-3-butyl-2-ol (0.0663 g, 0.076 mL, 0.788 mmol) was added. The mixture was heated at reflux temperature, with the initial yellow color turning to brown. The reaction was monitored by TLC (eluent: petroleum ether/ethyl acetate 5/1) for 24 h, until the substrate **3** disappeared. The mixture was cooled to room temperature, and CH2 Cl2 (25 mL) was added. The solution was washed with a saturated NaHCO3 aqueous solution (25 mL) and H2O (25 mL), dehydrated with MgSO4 and filtered, and the solvent was evaporated under vacuum. The crude product was purified by column chromatography on silica (petroleum ether/ethyl acetate 5/1 as eluent) to give **4** (0.1568 g, 0.474 mmol, yield 68%). 1'H NMR (CD2 Cl2, ppm), \(\delta_{\text{H}}\): 7.30 (dd, 1H, H5-, 3) = 5.1 Hz, 4' = 1.0 Hz); 7.24 (dd, 1H, H3-, 3) = 3.6 Hz, 4' = 1.0 Hz); 7.13 (d, 1H, partially overlapped, 3) = 3.6 Hz); 7.07 (dd, 1H, H4-, 3) = 5.1, 3.6 Hz); 7.07 (d, 1H, J = 3.6 Hz); 2.17 (s, 1H, OH); 1.62 (s, 6H, CH3). IR (KBr, cm\({}^{-1}\)): 3342 (OH), 2203 (C\(\equiv\)C). _Synthesis of 5-ethynyl-2,2'.5',2''-terthiophene_ (**5-ET**). 5-(3-hydroxy-3-methylbutyn-1-yl)-2,2'.5',2''-terthiophene (**4**, 0.2654 g, 0.803 mmol) was dissolved in toluene/methanol 1/1 (previously deoxygenated), and a large excess of KOH was added (KOH/substrate 10/1). The reaction mixture was stirred at reflux temperature and monitored by TLC (eluent: petroleum ether/ethyl acetate 5/1) for 24 h, until the substrate disappeared. The mixture was cooled at room temperature and the solvent was concentrated to a small volume. Then, water (50 mL) was added, and the organic phase was extracted with CH2 Cl2 (3 \(\times\) 50 mL), washed with a saturated NH4 Cl aqueous solution (200 mL), treated with MgSO4 and filtered. The solution was evaporated to dryness, and the crude residue was purified by column chromatography on silica, using petroleum ether/ethyl acetate 5/1 as eluent. The compound **5-ET** was obtained (0.1845 g, 0.671 mmol, 84% yield) as a brown-reddish powder.