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Annulated Heteroc y clic Derivatives of 1,3,6,8‐Tetraazapyrene
Author(s) -
Martens Susanne C.,
Hahn Lena,
Lombeck Florian,
Rybina Arina,
Wadepohl Hubert,
Gade Lutz H.
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201300662
Subject(s) - chemistry , indolizine , bathochromic shift , trifluoroacetic anhydride , pyridine , intramolecular force , pyridazine , medicinal chemistry , toluene , quinoxaline , trifluoromethyl , stereochemistry , fluorescence , organic chemistry , alkyl , physics , quantum mechanics
Polyheterocyclic aromatic compounds combining the electron‐poor 1,3,6,8‐tetraazapyrene (TAPy) unit with electron‐rich heterocycles are reported. They were obtained as side‐products from the reaction of the tin “double salt” of tetraaminonaphthalene hydrochloride with trifluoroacetic anhydride in pyridine. Apart from the target product, 2,7‐bis(trifluoromethyl)‐1,3,6,8‐tetraazapyrene ( 1 ), several novel heteroaromatics were obtained resulting from the annulation of a furan ( 2 ) or indolizine unit ( 3 ) to the TAPy core. Upon recrystallization from methanol, methanol added to compound 2 to yield the racemate of the homochiral diastereomer [( R , R )‐ and ( S , S )‐ 2a ]. Compound 3 is strongly fluorescent ( φ = 0.68 in toluene) and the emission spectra display a significant bathochromic shift with increasing solvent polarity. The HOMO of 3 is located on the indolizine part of the molecule, whereas the LUMO primarily resides on the tetraazapyrene unit, which suggests considerable intramolecular charge transfer in the corresponding π*←π transition.