Luminescence of extended and folded N,N′-diarylureas

Frederick D Lewis*, Todd L. Kurth, Weizhong Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


The relationship between molecular structure and luminescence of a series of secondary and tertiary N,N′-diarylureas (aryl = phenyl, 2-naphthyl, 2-anthryl, and pyren-1-yl) has been investigated at 77 K and at room temperature in the glass-forming solvent methyltetrahydrofuran. The secondary diarylureas possess planar extended structures, whereas the tertiary diarylureas possess folded structures in which the aryl groups are face-to-face. The secondary and tertiary diphenylureas display broad, weak fluorescence attributed to an n,π* singlet state at low temperature and are non-fluorescent at room temperature. The other secondary diarylureas are strongly fluorescent both at 77 K and at room temperature. Their fluorescence resembles that of the parent arene and is assigned to a lowest π,π* singlet state. The fluorescence of the other tertiary diarylureas is similar to that of the secondary diarylureas at 77 K, but is broad and red-shifted in fluid solution, as a consequence of intramolecular excimer formation. The properties of these novel intramolecular excimers are compared with those of 1,3-diarylalkanes and paracyclophanes.

Original languageEnglish (US)
Pages (from-to)30-37
Number of pages8
JournalPhotochemical and Photobiological Sciences
Issue number1
StatePublished - Jan 1 2002

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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