Photophysical And Photochemical Properties Of Photochromic Diarylethenes Based On Phenanthrene And Perylene

Diarylethene is one kind of themost promising photochromic materials for the applications in information storage, metal ion sensor andbiomedicine because of their excellent fatigue resistance and its thermalirreversibility. As a result of that, numerous scientists have been attracted to designdiarylethene materialswith novel structures and develop theirapplication in other fields. In the preface, important structures and related properties of diarylethene materials were introduced according to their main application fields.Diarylethene derivatives based on phenanthrene containing methyl carboxylate and carboxylic groups were synthesized for the first time. The structure and stable geometry of the one containing methyl carboxylate were confirmed by single crystal X-ray diffraction, while the distance between the photo-reactive carbon atoms was 3.95 ?and not out of the active range oftraditional dithienylperfluorocyclopentene derivertives in crystalline phase. But the derivatives did not show any photochromism in crystal phase. In solution, open isomers of both compounds were colorless and after UV light irradiated,the solutions changed to wine red while a broad absorption peak at 550 nm appeared. The photochromic processes in different solvents with various polarity were monitored by absorption spectrophotometer. Photochromism of both compounds were hardly affected by solvent polarity. Especially, sodium salts of the one containing carboxylic groups are soluble in water and the photoreaction rate was hardly affected. It is crucial for its application in biology field. The luminescence of them was controllable. It is the basic property for their application in information storage media.More important, the exciting wavelength of its luminescence and photoreaction are different. This crucial property make its application in non-destructive read outinformation storage media possible. It was studied by density functional theory and the results indicated that the cyclization probably took place at the second rather than the first excited states.It was the first time to realize non-destructive read out by control the dispersion of electron cloud of excited states of photochromic molecules.A phenanthrene bridged photochromic diarylethene with two crown ethers as ion recognizing groups has been synthesized and characterized by single crystal X-ray diffraction. This material shows good photochromism and fatigue resistance.Only the closed form of this diarylethene derivative can form coordination complexes with Cu2+ and Hg2+ and at the same time, the combination of the photochromic material and metal ions would lead to the cycle opening of closed photochromic unit and color bleaching processes. This special property can be applied in visual detection of these two heavy metal ions not only in solution but also in solid state. The fluorescence of the diarylethene is sensitive to light, copper and mercury ions. As a result, a single molecular logic circuit was constructed by using the absorbance and fluorescence intensity at specific wavelength as outputs and appropriate combinational stimuli of UV/Vis light, Cu2+ and Hg2+ions as inputs.Moreover, the fluorescence of it is sensitive to historical input signals. Based on this, a key pad lock using three codes to open was fabricated.The photochromism of the diarylethene derivativesin solid states was studied. Two methods were tried to initiate the photochromism of them in solid states. First, metal organic frameworks materials were tried to synthesize by our photochromic materials and metal ions. As the porous structure of metal organic frameworks structure, the thiophene groups probably could rote freely in solid state of metal organic frameworks and relatedsolid powder show photochromic property.However, reliable single crystal X-ray diffraction data could not be obtained. The phenanthrene bridged photochromic diarylethene was finally introduced into the skeleton of FEVE fluorocarbon polymer and the photochromism was remained in solidifiedfilm.The polymer was used to develop a novel coating which can be written by UV light and erased easily.Finally, a novel photochromic material based on perylene was studied. Double 2,5-methyl thiophenes or mestyleneswere introduced into the bay area of perylene and hexatriene structure was formed.I found the one containing 2,5-methyl thiophene groups was photosensitive but the other one was photostable.The single crystal X-ray diffraction data of 1, 7-mestylenyl perylene diimide revealed plane of the perylene core was not twisted. Density functional theory calculation was applied to study the difference of photophysical and photochemical properties.