Remarkable effect of alkynyl substituents on the fluorescence properties of a BN-phenanthrene

• Alberto Abengózar,
• David Sucunza,
• Patricia García-García and
• Juan J. Vaquero

Beilstein J. Org. Chem. 2019, 15, 1257–1261, doi:10.3762/bjoc.15.122

• impressive effect of the presence of alkynyl substituents on the fluorescence quantum yield, which improved from 0.01 in the parent compound to up to 0.65 in derivatives containing a triple bond. Keywords: alkyne; BN-phenanthrene; cross-coupling; fluorescence; heterocycles; Introduction BN-polycyclic

• recently designed an efficient synthesis for one of the simplest BN-PAHs, namely BN-phenanthrene 1a [23]. We are interested in evaluating the reactivity [24] and properties of 1a in greater detail as this could provide valuable information that leads to a better understanding of the behaviour of BN

• -aromatics. Interestingly, 1a turned out to be weakly fluorescent [23], in contrast to other BN-phenanthrene isomers described previously [25][26]. The presence of aryl or amino substituents at C1, which can be introduced via bromination and subsequent palladium-catalyzed cross coupling, does not have a