Photochromism in Oriented Thin Films Prepared by the Hybridization of Diarylethenes in Clay Interlayers

The photochromism of 1,2-bis(2-methyl-3-thiophenyl)perfluorocyclo-pentene bearing two pyridinium substituents at each thiophenyl ring (1) in smectite clay thin films is the subject of the present study. In order to prepare oriented thin films with photochromic characteristics, the hybridization of cationic diarylethene molecules, 1, into the layered clay was carried out, and the structure and photochromic properties of these hybrid materials were investigated. Clay intercalated diarylethene exhibited typical photochromic behavior. Polarized spectroscopic data has confirmed the diarylethenes inside the clay to be present as a tilted monolayer. Although the photochromic efficiency of these hybrid materials gradually decreased upon repeated irradiation with alternative UV and visible light, photochromic degradation could be dramatically improved by the cointercalation of cationic surfactant molecules such as dodecylpyridinium ions.