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Studies on Solution and Solid-State Photoswitching and Fluorescence Properties of Bistable Photochromic Hydrazones.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Studies on Solution and Solid-State Photoswitching and Fluorescence Properties of Bistable Photochromic Hydrazones./
作者:	Shao, Baihao.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2021,
面頁冊數:	258 p.
附註:	Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
Contained By:	Dissertations Abstracts International83-03B.
標題:	Chemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28547168
ISBN:	9798538121755

Studies on Solution and Solid-State Photoswitching and Fluorescence Properties of Bistable Photochromic Hydrazones.
Shao, Baihao.

Studies on Solution and Solid-State Photoswitching and Fluorescence Properties of Bistable Photochromic Hydrazones. - Ann Arbor : ProQuest Dissertations & Theses, 2021 - 258 p.

Source: Dissertations Abstracts International, Volume: 83-03, Section: B.

Thesis (Ph.D.)--Dartmouth College, 2021.

This item must not be sold to any third party vendors.

The development of new photochromic systems and the optimization of their switching properties lay the foundation for the practical use of photoswitches. Hydrazone-based switches are a potent addition to the current switch toolkit because of the coupled configurational switching and bistability that enable multistep and persistent adaptive functions. In this thesis, I set out to conduct systematic structure-property analyses to gain insights into their photochromic and photophysical properties to develop high-performance hydrazone switches. First of all, I have identified two key factors that determine the thermal stability of the hydrazones: 1) electronic effects that alter the double bond character of the C=N unit through resonance and, 2) steric effects at the fjord region that regulate the ground-state stability of hydrazone E isomers. These insights allowed us to tune the thermal half-lives of the switches from thousands of years to several days. Crystallographic studies have helped us reveal that the unique solid-state fluorescence and switching properties of the hydrazones are highly dependent on the crystal packing, i.e., the emission and photoisomerization processes become more efficient when the packing is loose. In addition, I discovered a push-pull hydrazone which undergoes E/Z photoisomerization driven by solely visible light while maintaining its bistability.I also discovered that NMe2-subsituted hydrazones have another unique feature: their emission can be switched ON and OFF in solution (organic and aqueous solution including serum) and the solid-state. This property allowed us to devise a real-time laser writing demonstration where different words and patterns were repeatedly drawn onto a toluene solution or a solid film. Further studies of the NMe2-hydrazone disclose that the fluorescence can also be turned ON and OFF using chemical stimulus (i.e., acid and base) and its thermal half-life gets tremendously accelerated (from years to hours) by acid.Another interesting class of hydrazones I have discovered are fluorophores with NMe2-substituted naphthyl moiety which show excitation-dependent emission. These hydrazones exhibit two emission bands whose relative intensity can be modulated by simply changing excitation wavelengths. The linear combination of two emissions results in a variety of colors, including white light emission.

ISBN: 9798538121755Subjects--Topical Terms:

516420
Chemistry.
Subjects--Index Terms:

Dye

Studies on Solution and Solid-State Photoswitching and Fluorescence Properties of Bistable Photochromic Hydrazones.
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500 $a Source: Dissertations Abstracts International, Volume: 83-03, Section: B.
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506 $a This item must not be sold to any third party vendors.
520 $a The development of new photochromic systems and the optimization of their switching properties lay the foundation for the practical use of photoswitches. Hydrazone-based switches are a potent addition to the current switch toolkit because of the coupled configurational switching and bistability that enable multistep and persistent adaptive functions. In this thesis, I set out to conduct systematic structure-property analyses to gain insights into their photochromic and photophysical properties to develop high-performance hydrazone switches. First of all, I have identified two key factors that determine the thermal stability of the hydrazones: 1) electronic effects that alter the double bond character of the C=N unit through resonance and, 2) steric effects at the fjord region that regulate the ground-state stability of hydrazone E isomers. These insights allowed us to tune the thermal half-lives of the switches from thousands of years to several days. Crystallographic studies have helped us reveal that the unique solid-state fluorescence and switching properties of the hydrazones are highly dependent on the crystal packing, i.e., the emission and photoisomerization processes become more efficient when the packing is loose. In addition, I discovered a push-pull hydrazone which undergoes E/Z photoisomerization driven by solely visible light while maintaining its bistability.I also discovered that NMe2-subsituted hydrazones have another unique feature: their emission can be switched ON and OFF in solution (organic and aqueous solution including serum) and the solid-state. This property allowed us to devise a real-time laser writing demonstration where different words and patterns were repeatedly drawn onto a toluene solution or a solid film. Further studies of the NMe2-hydrazone disclose that the fluorescence can also be turned ON and OFF using chemical stimulus (i.e., acid and base) and its thermal half-life gets tremendously accelerated (from years to hours) by acid.Another interesting class of hydrazones I have discovered are fluorophores with NMe2-substituted naphthyl moiety which show excitation-dependent emission. These hydrazones exhibit two emission bands whose relative intensity can be modulated by simply changing excitation wavelengths. The linear combination of two emissions results in a variety of colors, including white light emission.
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653 $a Dye
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