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Synthesis And Properties Of Diarylethenes Based On Five And Six-membered Carbohydrate

Posted on:2014-06-09Degree:MasterType:Thesis
Country:ChinaCandidate:Z P TongFull Text:PDF
GTID:2251330401980850Subject:Applied Chemistry
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As a member of organic photochromic compounds, diarylethenes have beenextensively investigated due to their excellent thermal stability and remarkablefatigue resistance. So far, it has emerged as a new research hotspot for biologicalapplications field. Therefore, it is necessary for photochromic diarylethenes todissolve in aqueous solution. However, most of the reported diarylethenes are verydifficult to dissolve in aqueous solution. It has attracted extensive attention to thedesign and synthesise of novel water-soluble diarylethenes.In this thesis, eleven symmetrical and asymmetrical photochromic diaryletheneswere synthesized. Carbohydrates were introduced to a diarylethene skeleton for thefirst time. Their structures were characterized by NMR, UV and IR. The substituenteffects on their optoelectronic properties were investigated in detail. The maincontents and results are generalized as follow:In chapter1, the basic concept, principle, and classification of photochromiccompounds are expounded. The application and latest progress of diarylethenes areintensively introduced.In chapter2, the water-soluble diarylethenes of DT-1~4were designed andsynthesized. Saccharide moieties were attached to two sides of these compounds. Allof these diarylethenes exhibited good photochromic properties in solution, but theirfatigue resistances were unsatisfactory. The fatigue resistant characteristics ofDT-1c~4c in water indicated that about50%of these comounds were destroyed after10repeat cycles. The thermal stabilities of DT-1c~4c in water indicated that theintroduction of phenyl rings was effective to enhance their thermal stability. Thesolubilities of DT-1o~4o in water were measured at room temperature. Experimentalresults indicated that the water solubility decreased with increasing number ofphenyl groups at room temperature.In chapter3, diarylethenes DT-5~7were designed and synthesized. There is axylose group on one side of these compounds. It was found that all of thesecompounds could not dissolve in water. Therefore, the optoelectronic properties of these compounds were investigated in acetonitrile. All of these diarylethenesexhibited good photochromic properties in solution and PMMA films. The results offatigue resistance study of DT-5c~7c showed that electron-withdrawing groups onthe other side could enhance fatigue resistance slightly, and electron-donating groupson the other side could reduce fatigue resistance slightly. The thermal stabilities ofDT-5c~7c in acetonitrile indicated that electron-donating groups could enhancethermal stability and the electron-withdrawing groups could reduce thermal stability.Further study of fluorescence properties of DT-5c~7c showed that it has no obviouseffects on emission wavelength, excited wavelength, and fluorescence quenchingefficiency when the hydrogen atom at the para-position of the terminal benzene ringwas replaced with either an electron-donating substituent or electron-withdrawingsubstituent, but the emission intensity of the diarylethenes with anelectron-withdrawing group was much better than that of diarylethenes with anelectron-donating group in acetonitrile.In chapter4, diarylethenes DT-8~10were designed and synthesized. Comparedwith DT-5~7in chapter3, DT-8~10had one more phenyl between thienyl and xylosegroup. It was also found that all these compounds could not dissolve in water.Therefore, the optoelectronic properties of these compounds were investigated inacetonitrile. For open-ring isomers of DT-8~10, electron-withdrawing groups at thepara-position of the terminal benzene ring could reduce their molar absorptioncoefficients, while electron-donating group could enhance molar absorptioncoefficients. For the closed-ring isomers of DT-8~10, electron-withdrawing groups atthe para-position of the terminal benzene ring could enhance their molar absorptioncoefficients while electron-donating group could reduce molar absorptioncoefficients. For DT-8~10, cyclization quantum yield could be enhanced andcycloreversion quantum yield could be reduced when the hydrogen atom at thepara-position of the terminal benzene ring was replaced with either anelectron-donating substituent or electron-withdrawing substituent. The DT-10c withan electron-withdrawing group is more stable than the other two compounds at roomtemperature. The results of fatigue resistance study of DT-8c~10c showed thatelectron-donating group could enhance fatigue resistance slightly, while electron-withdrawing group could reduce fatigue resistance slightly. Although thefatigue resistance of DT-8c~10c in PMMA films followed the same law as that inacetonitrile, the fatigue resistance of DT-8c~10c in PMMA films was much worsethan that in acetonitrile.In chapter5, a novel photochromic diarylethene with a salicylidene Schiff basesubstituent was designed and synthesized. The DT-11showed weak fluorescence, butthe fluorescence intensity of DT-11was significantly enhanced and red-shifted bythe addition of TEA and Al(III). The color of fluorescence of DT-11induced by TEAand Al(III) were orange red and bluish yellow, respectively. The fluorescenceintensity of deprotonation DT-11could been quenched by TFA and UV, and thefluorescence intensity of DT-11complextion with Al(III) could be quenched byEDTA. Hence, DT-11had multi-fluorescent switches.
Keywords/Search Tags:Diarylethenes, Saccharide, Photochromism, Effects of substitution, Water solubility
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