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Benzyl functionalized benzotriazole containing conjugated polymers: effect of substituent position on electrochromic properties and synthesis of crown ether functionalized electrochromic polymers

Yiğitsoy, Başak
A new class of π-conjugated monomers was synthesized with combination of electron donating and electron-withdrawing heterocyclics to understand the effects of structural differences on electrochemical and optoelectronic properties of the resulting polymers. Electron deficient benzotriazole, substititued with benzyl from two available sites, coupled with stannylated electron donating groups, ethylenedioxythiophene (EDOT) and thiophene (Th), to yield four different monomers; 1-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3] triazole (BBTA), 2-benzyl-4,7-di(thiophen-2-yl))-2H-benzo[d][1,2,3] triazole (BBTS), 1-benzyl-4,7-bis(2,3-dihydrothieno[3,4-b]dioxin-5-yl)-2H-benzo [d][1,2,3]triazole (BBTEA), 2-benzyl-4,7-bis(2,3-dihydrothieno[3,4-b]dioxin-5-yl)-2H-benzo [d][1,2,3]triazole (BBTES). Furthermore, EDOT and thiophene terminated napthalene-2,3-crown ether containing monomers, 14,19-di(thiophen-2-yl)-naphtho[2,3-b][1,4,7,10,13] pentaoxacyclo pentadecane (TNCT), 14,19-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-naphtho[2,3-b][1,4,7,10,13]pentaoxacyclopenta decane (ENCE), were synthesized to observe the effect crown ether moiety on the final electrochemical and optoelectronic properties of resultant polymers. Cyclic voltammetry, UV-Vis-NIR spectroscopy and colorimetry techniques were employed to examine electrochemical and optoelectronic properties of all monomers and polymers. Experimental results showed that alteration of substituent, substitution position and donor groups’ strength lead to obtain polymers with different redox behaviors, optical band gaps and different number of achievable colored states.