The effect of para- and meta-substituted fluorine on optical behavior of benzimidazole derivatives

Design, synthesis, and electrochemical properties of two novel donor-acceptor-donor type benzimidazole and thiophene based monomers; 2-(4-fluorophenyl)-4,7-di(thiophen-2-yl)-1H-benzo[d]imidazole (BIPF) and 2-(3-fluorophenyl)-4,7-di(thiophen-2-yl)-1H-benzo[d]imidazole (BIMF) were highlighted. The position of fluorine as a substituent was varied from para- to meta- in order to investigate position effects on the electrochemical and optical properties of electrochemically synthesized polymers. Both polymers were p type dopable and they can be switched between orange and blue color during p-doping/dedoping. Significant improvements in the percent transmittance for PBIMF were observed compared to similar molecules in literature.