A series of novel pyrrolidene imines and an ethene derivative bearing functionalized benzothiazole or benzothiazolium acceptor groups were synthesized, characterized and their photochromic properties, at room temperature, evaluated using the photostationary technique. While the imines did not show significant photochromic properties, visible irradiation of the diarylethene derivative led to a fast trans-cis isomerization of the C=C bond, with the concomitant change in the absorption spectrum. The cis isomer is not thermally stable and, in the absence of light, re-isomerizes slowly back to the trans form. ; Fundação para a Ciência e a Tecnologia (FCT)