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3,4-Vinylenedioxythiophene (VDOT): a new building block for

3,4-Vinylenedioxythiophene (VDOT): a new building block for thiophene-based π -conjugated systems Philippe Leriche,* Philippe Blanchard,* Pierre Fre`re, Eric Levillain, Gilles Mabon and Jean Roncali. Chem. Commun., 2006, 275–277 |. J. Mater. Chem., 2005 , 15 , 2077–2088.

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3,4-Vinylenedioxythiophene (VDOT): a new building block for

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  1. 3,4-Vinylenedioxythiophene (VDOT): a new building block for thiophene-based π-conjugated systems Philippe Leriche,* Philippe Blanchard,* Pierre Fre`re, Eric Levillain, Gilles Mabon and Jean Roncali Chem. Commun., 2006, 275–277 |

  2. J. Mater. Chem., 2005, 15, 2077–2088 PSS (polystyrene sulfonic acid)

  3. The strong electron-donating ether groups at the 3 and 4 positions of the thiophene ring i) the prevention of linkage defects during polymerization ii) an enhancement of the reactivity of the coupling α-positions iii) the self-rigidification of the π-conjugated chain by non-covalent intramolecular sulfur–oxygen interactions 4 3 2 1

  4. The modification of the chemical structure of the EDOT system the lengthening of the alkylene bridge Adv. Mater., 2000, 12, 481. the substitution of sulfur by selenium Org. Lett.,2001, 3, 4283. the replacement of one of the ether groups by a sulfide one Org. Lett., 2002, 4, 607. 3,4-phenylenedioxythiophene (PheDOT) J. Mater. Chem.,2004, 14, 1396.

  5. 3,4-dimethoxythiophene 3,4-diiodoethyloxythiophene elim.- HI p-toluenesulfonic acid t-BuOK t-BuOH / reflux 2-iodoethanoll toluene / reflux 84 % 82 % toluene reflux 2nd generation Grubbs catalyst oxidative coupling CuCl2 n-BuLi, THF, -70 oC 74 % 80 %

  6. smaller than the sum of the van der Waals ( 3.25 Å) 3.44 Å sp2 2.92 Å sp3 ORTEP view of BEDOT

  7. λmax = 309 nm shoulder at 298, 325 nm 11 nm blue shift of λmax compared to BEDOT 1. decrease of the electron releasing effect of the oxygen atoms towards the bithiophenic π-conjugated system 2 . the self-rigidification by non-covalent S–O interactions

  8. Stronger electron donor

  9. electrochemical polymerization : 應用電化學方法在陰極上或陽極上進行的聚合反應 ploy(BEDOT) : 0.07 V 0.4 V has a higher ionization potential than poly(BEDOT) and that the neutral state should therefore be more stable in air Eg = 1.70 eV - 1.8 V

  10. Spectroelectrochemistry : 施加不同電位之UV/Vis 光譜, 探討導電高分子的電化學聚合機制 530 nm (還原態吸收) 850 nm (部分氧化態吸收) 1500 nm polaron state (radical cation) (最高氧化態吸收) Eg = 1.65 eV Eg = 1.67 eV

  11. Summary 1. 3,4-vinylenedioxythiophene (VDOT) has been synthesized by ring-closing metathesis. The X-ray data for the dimer reveal more compact crystal structure than that of BEDOT consistent with stronger π-intermolecular interactions 2. This property associated with the higher oxidation potential of 2 and its polymer suggests that VDOT-based extended π-conjugated systems should exhibit a better environmental stability than their EDOT analogs

  12. 電化學聚合(electrochemical polymerization,縮寫為ECP)是指應用電化學方法在陰極上 或陽極上進行的聚合反應。 按照鏈增長的歷程可以把化學聚合反應分為縮合聚合反應和加成聚合反應兩大類。 縮聚反應是具有兩個或兩個以上反應官能團的低分子化合物相互作用而生成大分子的過程，其大分子鏈的增長為一逐步增長過程。加聚反應是從烯類單體或環狀單體出發，通過反復多次的加成作用而生成大分子的過程。其大分子鏈的增長為一鏈式增長過程，也即單體分子通過與聚合物活性鏈的活性中心發生反應而加成到活性鏈中。按照不斷生長的聚合物活性鏈的活性中心的性質，加聚反應又可分為三類：自由基型加聚反應，陽離子型加聚反應和陰離子型加聚反應。

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