Photochromic Bisthienylethene Functional Materials With Ions Recognition And Dye-Sensitized Ability

During the photoisomerization, not only their chemical structures but also their various physical and chemical properties change, such as absorption spectra, photoluminescence, oxidation/reduction potential, optical activity, electrical conductivity, magnetic interactions, refractive index, chiral properties, and dielectric constant. Among various types of photochromic compounds, diarylethene derivatives are the most promising candidates because of their fatigue resistant and thermal irreversible properties. In this thesis, several novel unsymmetrical photochromic diarylethene derivatives were developed. The main contents and results are generalized as following:In Chapter1, the development and application of photochromic materials are reviewed, and at last the target of our research was brought out.In Chapter2, two novel NIR photochromic compounds with electron-donating and electron-accepting groups (1a and1b) have been designed and synthesized. Their NIR photochromic behaviors, with a large red shift in absorption maxima upon photocyclization by D-π-A system, have been studied. Their fluorescence can be modulated due to nucleophilic addition of cyanide anion to dicyanovinyl group, acting as probes for cyanide anion. Moreover, their sensory properties toward the cyanide anion, which could modulate the NIR photochromic behaviors, have been explored. This novel idea facilitates the development of NIR photochromic compounds and NIR chemosensor for future colormetric sensors of lethal ions and toxic pollutant.In Chapter3, a new photochromic compound S1, containing the trans-cis photoisomerization unit and chemosensor unit for the detection of mercury, has been designed and synthesized. The S1displayed dramatic changes in fluorescence intensity selectively for mercury ion over other ions in CH3CN. In addition, in the photostationary-state, colormetric response to mercury ion was achieved. Sequentially, a double-check mercury ion chemosensory system was developed with both fluorometric detection in open isomer as the first check and colorimetric measurement in the photostationary state as the second check. This novel idea facilitates the development of double-check chemosensor for future sensors of lethal ions and toxic pollutant.In Chapter4, two novel bisthienylethenes with indene as the bridging unit have been synthesized through a simple and efficient one-step method and their properties also have been investigated. This new photochromic system presented good thermal stability and fatigue resistance in the solution. Importantly, we found that the fluorescence intensity of1and2can be regulated in a reversible manner by the photoisomerization in solution and film.1and2can be proposed as a promising candidate for storage of optical information with the capability of repeated "re-recording".In Chapter5, we try to use photochromic dyes in dye-sensitized solar cells as sensitizers and find an interesting phenomenon that the color of the device change in succession with the irradiation time under365nm UV light and a series of photoelectric data was got. We also discovered that even the sensitizers and semi-conductor match each other in the case of the energy level, to broaden the absorption spectrum of the sensitizer may not improve its photoelectric properties. The photoelectric conversion performances of DSSCs are also related to the orbital electron distribution as well as the impedance of inhibition electronic recombination.In Chapter6, other work:a range of new boronic acid compounds containing diarylethene for the detection fluoride ion were prepared. The fluorescence products were purified by silica-gel-column chromatography and characterized by1H NMR, and HRMS. And, the sensing mechanism in this photochromic fluoride sensor was assumed. Moreover, naphthalene unit was introduced into the ethene bridge of bisthienylethene as a part of the photochromic materials. However, BTE is without photochromic properties due to the effection of the nitrogen atom.In Chapter7, a conclusion about the above work was given.