1 / 2

多吩類衍生物經光敏化作用產生之單線態氧的測定及在有機溶劑中其產率之評比

多吩類衍生物經光敏化作用產生之單線態氧的測定及在有機溶劑中其產率之評比.

kimn
Download Presentation

多吩類衍生物經光敏化作用產生之單線態氧的測定及在有機溶劑中其產率之評比

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 多吩類衍生物經光敏化作用產生之單線態氧的測定及在有機溶劑中其產率之評比多吩類衍生物經光敏化作用產生之單線態氧的測定及在有機溶劑中其產率之評比 • 根據二吩及三吩衍生物的研究結果，此類衍生物在照光時會有光毒性，而光毒性的來源是光敏化效果所產生的單線態氧。利用此一特性多吩類衍生物或可開發成新的光化學療劑。為此目的本研究以五種多吩類衍生物為原料，分別為2,2':5',2''-三吩（alpha-terthienyl，以下簡稱aT），1,2-二（2-吩）乙炔（1,2-bis(2-thienyl)acetylene，以下簡稱BTA），(E)-1,2-二（2-吩）乙烯（(E)-1,2-bis(2-thienyl)ethene，以下簡稱BTE），5-甲醛-2,2':5',2''-三吩（5-formyl-2,2':5',2''-terthiophene，以下簡稱FTT），和5-（2-（2-亞胺）乙基乙醇）-2,2':5',2''-三吩（(5-(2-(2-imino)-aminoethyl)-ethanol)-2,2':5',2''-terthiophene，以下簡稱IAET），用單線態氧捕捉劑2,5-dimethylfuran和1,3-diphenylisobenzofuran證明這些結構式經修飾的衍生物仍會在照光時產生單線態氧，再以高效液相層析儀分析這些衍生物在甲醇、氰甲烷、乙醇及異丙醇等四種溶劑下對其單線態氧產率的影響。實驗結果顯示，aT與FTT有最大的單線態氧產率，又以在氰甲烷中產率最高。BTA、BTE和IAET的單線態氧產率很低，此外BTE和IAET會在照光過程中發生結構式變化。此結果顯示多吩類衍生物進行的光反應途徑有兩種：產生單線態氧（如aT與FTT）或光解產物（如BTE與IAET）。其差異點在於多吩類衍生物之最大吸收波長的吸收強度，此類衍生物之最大吸收波長的吸收乃由電子的傳遞效應所引起，電子傳遞效應高者會使鍵結斷裂形成光解產物，反之則可保持結構式安定而產生單線態氧。另外單線態氧在不同溶劑下的半衰期之長短對此類衍生物的單線態氧產率恰成正比。

  2. Determination of Singlet Oxygen and Evaluation of Its Generating Efficiency via Photosensitization of Polythiophene Derivatives in Organic Solvents • According to some previous research reports of bithiophene and terthiophene derivatives, singlet oxygen photosensitized by poly-thiophene derivatives would be the mechanism leading to their phototoxicity. This property has high potential to be developed into photochemotherapy agents. Here we use singlet quenchers, 2,5-dimethylfuran and 1,3-diphenylisobenzofuran to prove singlet oxygen which was generated by some polythiophene derivatives of alpha-terthienyl(aT), 1,2-bis(2-thienyl)acetylene(BTA), (E)-1,2-bis(2-thienyl)ethene(BTE), 5-formyl-2,2':5',2"-terthiophene(FTT), and (5-(2-(2-imino)-aminoethyl)-ethanol)-2,2':5',2"-terthiophene(IAET) under irradiation. The effect of different organic solvents of methanol, acetonitrile, ethanol, and propan-2-ol on singlet oxygen quantum yield was assayed by HPLC method. • The results show that aT and FTT have higher value of singlet oxygen quantum yield, and singlet oxygen can be detected more in acetonitrile than in other solvents. It is due to the lifetime of singlet oxygen in solvents. BTA, BTE, and IAET hardly generate singlet oxygen; BTE and IAET undergo photodegradation during irradiation. It suggests that there are two pathways of photochemical reactions for polythiophene derivatives to either generate singlet oxygen (such as aT and FTT) or photolysis(such as BTE and IAET). The mechanisms of photochemical reactions of polythiophene derivatives are upon the molar absorptivity of their maximum absorption band which is characteristic of an electron transfer transition. The higher value of the effect of an electron transfer transition would lead polythiophene derivatives to photolysis while the lower would lead to generate singlet oxygen.

More Related