Title

Optimizing the Discovery and Processability of Biologically Derived Molecular Glass Host Materials for Photonic Applications

Author

John J. Flynn

Date of Award

1-1-2020

Degree Name

M.S. in Chemical Engineering

Department

Department of Chemical and Materials Engineering

Advisor/Chair

Advisor: Erick Vasquez

Abstract

?-Estradiol and cholesterol host-guest molecular glasses have been demonstrated in literature to enhance chromophore lifetimes, exhibiting long-lived room temperature phosphorescence (RTP) on the order of 10^0 s. A series of four steroids, ?-estradiol, cholesterol, lithocholic acid (LCA), and ?-sitosterol are investigated using thermal and photophysical techniques to identify alternative host materials that enable RTP.Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) provided a high-throughput analysis platform to identify and establish stable glass formulations and guest chromophore loading limits. A newly identified host candidate, LCA, was shown to be a suitable glass former and further demonstrated to have the highest capacity for anthracene loading of the host steroids investigated in this study. The high-throughput DSC analysis technique was demonstrated in a proof-of-concept using a donor-acceptor system prior to photophysical analysis.Glassy thin films of neat steroids and host-guest systems containing anthracene were investigated. Four thin film preparation techniques were explored. Down-selected techniques were analyzed using UV-vis spectroscopy and contact profilometry for reproducibility in the thin film thickness and guest loading.The spectroscopic and kinetic behavior of anthracene doped thin films of ?-estradiol and LCA were compared in order to evaluate the effect of the host glass on the photophysical properties of the guest. Fluorescence was shown to be largely unaffected by the choice of host, while anthracene phosphorescence was demonstrated to be extended in host steroids. LCA was shown to perform comparably well with ?-estradiol. The study is completed with a demonstration of an Ir - d10-pyrene donor-acceptor system achieving lifetimes on the order of 0.4 s.

Keywords

Physical Chemistry, Electromagnetics, Materials Science, Optics, Long-Lifetime Materials, Room Temperature Phosphorescence, Steroid Host Guest, Donor-Acceptor Chromophores, Molecular Glass, Differential Scanning Calorimetry, Lithocholic Acid

Rights Statement

Copyright 2020, author

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