Photochromic Performance of Novel Dithia-dithienylethenophanes

Photochromic molecules attract much attention because of their potential application to optoelectronic devices, such as optical memory media, photooptical switching and display. Here we have synthesized novel compounds dithia-dithienylethenophane derivatives and investigated photochromic performance in solution. Our main intention is restricted the rotation and fixation in a suitable position of dithia-dithienyl-ethenophane by using bridge chain and benzene ring for enhancement the photocyclization quantum yield. Dithia-dithienylethenophane is the first example of a dithienylethene bridged with a benzene ring. The dithia-dithienylethenophane derivatives exhibited photochromic properties upon irradiation with UV/VIS light. The distances between the reactive carbon atoms of the energy minimized structures of the open form were related to photocyclization quantum yields and those of ortho, meta and para isomers are 3.96 Å, 4.26 Å, 4.68 Å and 0.51, 0.42, 0.11, respectively. The thermal stabilities of the ortho, meta and para isomer of dithia-dithienylethenophane were examined at 100oC in toluene and the both photoisomers of the ortho isomer were thermally stable.