Photoregulating fluorescence and self-assembly in thin films using Dithienylethene molecular switches

A hybrid system containing a Zn-bis(amidine) fluorescent dye covalently joined to two photochromic dithienylethene (DTE) units was prepared to investigate the fluorescence switching property.. UV-Vis absorption and emission spectroscopy showed that the fluorescence switching process has little effect on the photocyclization process and the fluorescence could be turned “on” and “off” for ten cycles without notable side products appearing. This fluorescence switching property can be potentially used in non-destructive read out and biological labelling applications. Two photoresponsive DTE derivatives were decorated with fatty acids to investigate whether the geometrical changes of the ring-open and ring-closed isomers of the DTE can be used to effect the packing of the molecule within a membrane structure, which can be potentially useful in drug delivery. Although one of the two derivatives showed excellent photochromic properties, the changes between the structures of two isomers were not significant enough to be useful in drug delivery.