Bistricyclic aromatic enes annelated with nopinane fragment

• Published in: Tetrahedron 2021-03, Vol.83, p.131979, Article 131979
• Main Authors: Vasilyev, Eugene S., Bizyaev, Sergey N., Komarov, Vladislav Yu, Tkachev, Alexey V.
• Format: Article
• Language: English
• Subjects: 4,5-Diazafluorene; Mechanochromism; Nopinane-annelated pyridines; Overcrowded alkenes; pH sensing
• ISSN: 0040-4020; 1464-5416
• DOI: 10.1016/j.tet.2021.131979

Organic compounds, referred to as bistricyclic aromatic enes (BAE), are a subgroup among many sterically overcrowded alkenes and are widely studied as molecular switches. We have developed a new group of chiral BAE whose molecular structure combines dipinodiazafluorene fragment and chromophore/fluorophore (acridine, xanthene or thioxanthene moiety). The new compounds demonstrate mechanochromism, thermochromism, and solvatochromism/protonochromism. According to quantum chemical calculations (DFT PBE0/def2-TZVPP), the compounds synthesized are conformationally inhomogeneous, and the conformations should differ in the electronic absorption spectra, the population of conformational isomers should being dependent on the solvent and the acidity of the medium. The observed experimental facts (NMR data, UV spectra, chromism, X-ray data) are in good correlation with the calculated data. [Display omitted] •A new group of chiral BAE have developed, whose structure combines dipinodiazafluorene and chromophore/fluorophore moieties.•The new compounds demonstrate mechanochromism, thermochromism, and solvatochromism/protonochromism.•Calculations show (DFT PBE0/def2-TZVPP) the color phenomena to be due to the conformational inhomogenity of the compounds.