Photochromic Bisthienylethene Functional Materials

During the photoisomerization process of the photochromic compounds, not only the absorption spectra but also the photochemical and photophysical properties of the compounds will be changed, such as electric constant, refractive index, luminescence, oxidation-reduction potential and so on. Among these outputs, luminescence is considered as one of the most promising application for optical information storage and molecular switches owing to its easy operation, fast response and preparation devices with low-cost. In recent years, photochromic bisthienylethene compounds have aroused surge of interest with their excellent thermal stability and fatigue resistance properties.In chapter one, the development of organic photochromic compounds has been reviewed.In chapter two, a novel iridium complex coordinating to the photochromic diarylethene derivative Py-BTE was prepared and near infrared photochromic behaviors of (Py-BTE)2Ir(acac) complex were investigated. (Py-BTE)2Ir(acac) showed excellent photochromic properties such as thermal stability and fatigue resistance accompanied by efficient quenching of phosphorescence emission by the closed form of the diarylethene moiety. With the phosphorescent derivated from the characteristic triplet state of iridium ion, a long-wavelength stimulated photochromic phosphorescence switch was designed. The target compound, (Py-BTE) 2Ir (acac), is an outstanding luminescence switching. Its phosphores-cence change can also be measured at room temperature, which is more available than other photochromic metal complexes to be measured at 77 K. The photochromic Iridium complex extended the excitation wavelength to lower energy, which is possibly used as non-destructive readout.In chapter three, the diarylethene unit has been induced to the aromatic position of high-fluorescent perylene unit for the first time. The target compound, PDI-DTE, showed good photochromic properties and thermal stability. After UV irradiation, the cyclization of dithenylethene unit affected the fluorescence properties of perylene imide unit. The color of the compound hasn't changed while the fluorescent increased after UV light irradiation. Thus with alternative irradiation by ultraviolet light and visible light, the difference of PDI-DTE can not be identified by the naked eyes. So PDI-DTE has potential application in the anti-counterfeiting area.In chapter four, incorporating boron trifluoride to the designed compound BTE-Q formed a similar structure as BODIPY. Bistheinylethene derivatives with cyclopentene as ethene bridge usually show rather small fluorescence intensity. However, BTE-BF is without photochromic properties due to the withdrawing effect of the nitrogen atom on the replaced methylquinoline. Thus may lead to the inhibitation of the cyclization reaction response to light irradiation.In chapter five, with easily synthesized high-performance fluorescent functional group naphthalimide decorated to side chain of the photochromic unit, the target compound BTE-NA has obtained. It shows excellent response to light modulation of the fluorescence. Also the fluorescence wavelength is blue shift accompany with the increasing of the solvent polarity, because of the solvent relaxation affection.In chapter six, a series of bisthienylethene iridium complexes were synthesized with different ligands, (Py-BTE) 2Ir (acac), (Py-BTE) 2Ir (pic) and (Py-BTE) 2Ir (bpy). These complexes all show good photochromic properties. The potential application for the cell probe may realized by the conversion of the ligands to achieve the water-soluble complexes.In chapter seven is other work.In chapter eight is the conclusion.