Preparation And Properties Of Photosensitive Spiropyran-containing Materials

Spiropyran is an organic photochromic molecule that can furnish reversible isomerization under various external stimuli.Due to the large differences in structure and property between the two isomers,spiropyran has become an important choice for the construction of intelligent systems.At present,although spiropyran compounds have been widely used in various fields,the low synthetic efficiency of spiropyrans largely limit their further practical applications.Here,we would present an efficient one-pot synthetic strategy for the construction of spiropyrans.Compared to the reported three-step synthesis,this method shows advantages in energy and time consuming as well as environment protection,by avoiding the use of special equipment and operations,and by tolerating with various solvents,base,aldehydes,and alkyl bromides.This one-pot synthetic strategy provides a feasible approach for the potential industrial production in future.Solid-state spiropyrans would be excellent materials for solar energy storage,information storage,etc.,if they could furnish the light-induced isomerization process at room temperature.However,solid-state spiropyrans with fully reversible photochromic properties at room temperature are extremely rare,due to the lack of sufficient free room for the photoisomerization process.In this work,via increasing the molecular flexibility,a new strategy for designing solid-state spiropyrans showing highly efficient reversible photochromism at room temperature has been developed.By attaching a flanking alkyl chain to the indole nitrogen,the as-prepared spiropyrans exhibit fast photoresponsive properties.More attractively,this kind of spiropyrans could be conveniently ‘‘evolved’’ into a new solid state showing advanced photochromic and thermochromic properties with three different colors(red,yellow and purple).With good room temperature stability and excellent one-to-one correspondences between stimuli and colors,these solid-state spiropyrans are proved to be advanced information storage materials.As the developed biomaterials in recent years,solvent-free DNA thermotropic liquid crystals could be fabricated by the electrostatic complexation of DNA and ammonium surfactant with flexible chains.up to now,regulations on the properties of DNA thermotropic liquid crystals by some external stimuli have been achieved.However,photoresponsive DNA thermotropic liquid crystals are still rare.in this work,two types of spiropyran-containing ammonium surfactants are synthesized for the fabrication of photoresponsive DNA thermotropic liquid crystals.The physical states and photoresponsive properties of DNA thermotropic liquid crystals highly rely on the stoichiometric charge ratios of DNA to surfactant during the sample preparations.the development of photoresponsive DNA materials based on spiropyrans would afford new candidate smart biomaterials logic gates and biosensing.