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Title: A Naphtho- p-quinodimethane Exhibiting Baird’s (Anti)Aromaticity, Broken Symmetry, and Attractive Photoluminescence

In this paper, we report a novel reductive desulfurization reaction involving π-acidic naphthalene diimides 1 (NDI) using thionating agents such as Lawesson’s reagent. Along with the expected thionated NDI derivatives 2-6, new heterocyclic naphtho-p-quinodimethane compounds 7 depicting broken/reduced symmetry were successfully isolated and fully characterized. Empirical studies and theoretical modeling suggest that was formed via a six-membered ring oxathiaphosphenine intermediate rather than the usual four-membered ring oxathiaphosphetane of 2-6. Aside from the reduced symmetry in 7 as confirmed by single-crystal XRD analysis, we established that the ground state UV-vis absorption of 7 is red-shifted in comparison to the parent NDI 1. This result was expected in the case of thionated polycyclic diimides. However, unusual low energy transitions originate from Baird 4nπ aromaticity of compounds 7 in lieu of the intrinsic Huckel (4n + 2)π aromaticity as encountered in NDI 1. Moreover, complementary theoretical modeling results also corroborate this change in aromaticity of 7. Consequently, photophysical investigations show that, compared to parent NDI 1, 7 can easily access and emit from its T 1 state with a phosphorescence 3(7a)* lifetime of τ P = 395 μs at 77 K indicative of the formation of the corresponding “aromatic triplet” species according tomore » the Baird’s rule of aromaticity.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3] ; ORCiD logo [4] ;  [1] ; ORCiD logo [1]
  1. Illinois Inst. of Technology, Chicago, IL (United States). Department of Chemistry
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Center for Nanoscale Materials
  3. North Dakota State Univ., Fargo, ND (United States). Department of Chemistry and Biochemistry
  4. Columbia Univ., New York, NY (United States). Department of Chemistry
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Organic Chemistry
Additional Journal Information:
Journal Volume: 82; Journal Issue: 19; Journal ID: ISSN 0022-3263
Publisher:
American Chemical Society
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; Illinois Institute of Technology, Chicago, IL (United States)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1427718