Variations of bistricyclic aromatic enes: Mono-bridged tetraarylethene naphthologs

Naela Assadi, Sergey Pogodin, Shmuel Cohen, Israel Agranat*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The syntheses, molecular and crystal structures, NMR spectroscopic study, and DFT computational study of naphthologs of mono-bridged (X = -, O, S, Se, and Te) tetraarylethene (BAE-1s) 11-25 with α,α-, β,β-, and α,β-dinaphthalenyl substituents have been reported. The BAE-1s have been prepared by Barton-Kellog twofold extrusion from the respective chalcogenothiones and diazomethylenebisnaphthylenes. Complete assignments of 1H- and 13C-NMR spectra of 11-25 have been made through 2-dimensional correlation spectroscopy (DQF-COSY, HSQC, HMBC, and NOESY). The corresponding intermediates, thiiranes 33-47, have been also isolated (except 38), and their molecular and crystal structures have been determined. The molecular structures of BAE-1s 12-15, 20, and 22-25 adopted folded-twisted conformations with considerably folded (φ = 30°-57°) tricyclic moieties. The α,α- and α,β-dinaphthalenyl derivatives are more overcrowded than β,β-dinaphthalenyl derivatives. The relief of the steric strain due to the overcrowding around C9 = C9' caused by the presence of naphthalenyl substituents was achieved by their twisting around the single bonds that connect the α-naphthalenyl and β-naphthalenyl moieties to C9'. The 1H-NMR spectra have shown shielding of H2, H7 of 11-25 and the pronounced deshielding of H8', H8′ of α,α-dinaphthalenyl-substituted BAE-1s 13-15 in contrast to β,β-dinaphthalenyl-substituted BAE-1s 16-20. The upfield shifts of H2, H7 suggested conformations in which these hydrogens are located above the planes of the opposing naphthalene rings. DFT calculations of 11-20 have been performed at B3LYP/6-31G(d) and B3LYP/SDD. The results have shown that the global minima of BAE-1s without a chalcogen bridge 11 and 16 are twisted (-sc,-sc)-C 2-t conformations. The global minima of BAE-1s with a chalcogen bridge are folded-twisted (-sc,-ac)-C 1-ft conformations for α,α-dinaphthalenyl-substituted BAE-1s 12-15 and either anti- or syn-(-sc,ac)-C 1-ft conformations for β,β-dinaphthalenyl-substituted BAE-1s 17-20. The pronounced differences between the α,α-dinaphthalenyl and the β,β-dinaphthalenyl derivatives are noted. Dispersion-corrected B3LYP calculations stabilize significantly the α,α-dinaphthalenyl derivatives versus the β,β-dinaphthalenyl derivatives. The geometrical parameters of BAEs-1 11-15 and 20, derived from their molecular X-ray structures and from their B3LYP-optimized geometries are in a good agreement.

Original languageEnglish
Pages (from-to)319-352
Number of pages34
JournalStructural Chemistry
Volume26
Issue number1
DOIs
StatePublished - Feb 2015

Bibliographical note

Publisher Copyright:
© 2014 Springer Science+Business Media New York.

Keywords

  • AIE luminogen
  • Conformations
  • DFT
  • Empirical dispersion correction
  • Naphthalene
  • NMR
  • Overcrowding
  • Se
  • Te

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