Convergent synthesis of nonsymmetric π-stacked protophanes assembled with urea linkers

Frederick D Lewis*, Grace B. Delos Santos, Weizhong Liu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

(Chemical Equation Presented) A convergent approach has been developed for the preparation of nonsymmetric tertiary arylureas possessing two or three urea linkages. This approach has been used for the preparation of ureas possessing 1-naphthylenyl and 4-nitrophenyl end groups separated by either one or two phenylene diamine bridging units. These ureas were constructed as prototypes for donor-bridge-acceptor systems based on tertiary arylurea architecture. AM1 calculations indicate a preference of these arylureas for folded, protophane structures in which the aryl groups are loosely π-stacked. Analysis of the 1H NMR chemical shifts supports the assignment of folded structures in solution. The absorption and luminescence spectra of tertiary ureas possessing 1-naphthylenyl and/or 4-nitrophenyl are reported. The absence of fluorescence and appearance of structured phosphorescence at 77 K are attributed to nitrophenyl-localized lowest energy singlet and triplet states. Localization of excitation on the acceptor chromophore precludes investigation of charge transfer in these systems.

Original languageEnglish (US)
Pages (from-to)2974-2979
Number of pages6
JournalJournal of Organic Chemistry
Volume70
Issue number8
DOIs
StatePublished - Apr 15 2005

ASJC Scopus subject areas

  • Organic Chemistry

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