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Title: Photostability Can Be Significantly Modulated by Molecular Packing in Glasses

Abstract

While previous work has demonstrated that molecular packing in organic crystals can strongly influence photochemical stability, efforts to tune photostability in amorphous materials have shown much smaller effects. Here we show that physical vapor deposition can substantially improve the photostability of organic glasses. Disperse Orange 37 (DO37), an azobenzene derivative, is studied as a model system. Photostability is assessed through changes in the density and molecular orientation of glassy thin films during light irradiation. By optimizing the substrate temperature used for deposition, we can increase photostability by a factor of 50 relative to the liquid-cooled glass. Photostability correlates with glass density, with density increases of up to 1.3%. Coarse-grained molecular simulations, which mimic glass preparation and the photoisomerization reaction, also indicate that glasses with higher density have substantially increased photostability. These results provide insights that may assist in the design of organic photovoltaics and light emission devices with longer lifetimes.

Authors:
 [1];  [2];  [2];  [1]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Chemistry
  2. Univ. of Chicago, IL (United States). Institute for Molecular Engineering
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1411404
Grant/Contract Number:
SC0002161
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 138; Journal Issue: 35; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Qiu, Yue, Antony, Lucas W., de Pablo, Juan J., and Ediger, M. D. Photostability Can Be Significantly Modulated by Molecular Packing in Glasses. United States: N. p., 2016. Web. doi:10.1021/jacs.6b06372.
Qiu, Yue, Antony, Lucas W., de Pablo, Juan J., & Ediger, M. D. Photostability Can Be Significantly Modulated by Molecular Packing in Glasses. United States. doi:10.1021/jacs.6b06372.
Qiu, Yue, Antony, Lucas W., de Pablo, Juan J., and Ediger, M. D. 2016. "Photostability Can Be Significantly Modulated by Molecular Packing in Glasses". United States. doi:10.1021/jacs.6b06372. https://www.osti.gov/servlets/purl/1411404.
@article{osti_1411404,
title = {Photostability Can Be Significantly Modulated by Molecular Packing in Glasses},
author = {Qiu, Yue and Antony, Lucas W. and de Pablo, Juan J. and Ediger, M. D.},
abstractNote = {While previous work has demonstrated that molecular packing in organic crystals can strongly influence photochemical stability, efforts to tune photostability in amorphous materials have shown much smaller effects. Here we show that physical vapor deposition can substantially improve the photostability of organic glasses. Disperse Orange 37 (DO37), an azobenzene derivative, is studied as a model system. Photostability is assessed through changes in the density and molecular orientation of glassy thin films during light irradiation. By optimizing the substrate temperature used for deposition, we can increase photostability by a factor of 50 relative to the liquid-cooled glass. Photostability correlates with glass density, with density increases of up to 1.3%. Coarse-grained molecular simulations, which mimic glass preparation and the photoisomerization reaction, also indicate that glasses with higher density have substantially increased photostability. These results provide insights that may assist in the design of organic photovoltaics and light emission devices with longer lifetimes.},
doi = {10.1021/jacs.6b06372},
journal = {Journal of the American Chemical Society},
number = 35,
volume = 138,
place = {United States},
year = 2016,
month = 8
}

Journal Article:
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Cited by: 5works
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  • Purpose: Xerostomia is a severe complication after radiotherapy for oropharyngeal cancer, as the salivary glands are in close proximity with the primary tumor. Intensity-modulated radiotherapy (IMRT) offers theoretical advantages for normal tissue sparing. A Phase II study was conducted to determine the value of IMRT for salivary output preservation compared with conventional radiotherapy (CRT). Methods and Materials: A total of 56 patients with oropharyngeal cancer were prospectively evaluated. Of these, 30 patients were treated with IMRT and 26 with CRT. Stimulated parotid salivary flow was measured before, 6 weeks, and 6 months after treatment. A complication was defined as amore » stimulated parotid flow rate <25% of the preradiotherapy flow rate. Results: The mean dose to the parotid glands was 48.1 Gy (SD 14 Gy) for CRT and 33.7 Gy (SD 10 Gy) for IMRT (p < 0.005). The mean parotid flow ratio 6 weeks and 6 months after treatment was respectively 41% and 64% for IMRT and respectively 11% and 18% for CRT. As a result, 6 weeks after treatment, the number of parotid flow complications was significantly lower after IMRT (55%) than after CRT (87%) (p = 0.002). The number of complications 6 months after treatment was 56% for IMRT and 81% for CRT (p = 0.04). Conclusions: IMRT significantly reduces the number of parotid flow complications for patients with oropharyngeal cancer.« less
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