Document Type

Article

Publication Date

8-22-2022

Publication Source

ChemPhotoChem

Abstract

Lithocholic acid was identified as a molecular glass host material for room temperature phosphorescent (RTP) chromophores. Differential scanning calorimetry (DSC) was performed on a series of structurally similar, biologically sourced molecules, including lithocholic acid, β-estradiol, cholesterol, and β-sitosterol, in an effort to identify new amorphous molecular glasses independent of plasticizing additives. DSC analysis revealed lithocholic acid and β-estradiol form stable molecular glasses post thermal processing unlike neat cholesterol and β-sitosterol. The ability of lithocholic acid and β-estradiol to stabilize high wt. % loadings of d10-pyrene and a mixture of d10-pyrene and an iridium chromophore, bis(2,4-difluorophenylpyridinato)-tetrakis(1-pyrazolyl)borate iridium(III) (FIr6), was also investigated. All β-estradiol formulations show β-estradiol cold crystallization. Optical microscopy and wide angle X-ray scattering measurements suggest spherulite β-estradiol crystals form during this process. Finally, time-resolved luminescence and phosphorescence quantum yield experiments show that the d10-pyrene RTP lifetime is longer and the d10-pyrene phosphorescence quantum yield is higher in lithocholic acid molecular glasses than in β-estradiol molecular glasses. The discrepancy in lifetime and quantum yield values is explained by quantitatively smaller rates of non-radiative decay from the triplet state of d10-pyrene in lithocholic acid.

ISBN/ISSN

Online ISSN: 2367-0932 Print ISSN: 2367-0932

Comments

This article has been contributed to by U.S. Government employees, and their work is in the public domain in the United States.

DOI: https://doi.org/10.1002/cptc.202200134

Publisher

John Wiley & Sons

Volume

6

Peer Reviewed

yes

Issue

12

Keywords

differential scanning calorimetry, host-guest systems, molecular glass, room-temperature phosphorescence, wide angle X-ray scattering

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