Synthesis of phenanthroline derivatives by Sonogashira reaction and the use of their ruthenium complexes as optical sensors

The phenanthroline derivatives, which have alkynyl groups, were synthesized by palladium-catalyzed, Sonogashira cross-coupling reaction to provide the following coupled products: 4,7-bis(4-phenylethynyl-phenyl)-[1,10]phenanthroline (6a) and 4,7-bis{4-(4-hydroxy-buty-1-ynyl)-phenyl)-[1,10]phenanthroline (6b) at 87 and 89% yield, respectively. Their ruthenium complexes, tris{4,7-bis(4-phenylethynyl-phenyl)-[1,10]phenanthroline} ruthenium(II) bis(hexafluorophosphate) (7a) and tris[4,7-bis{4-(4-hydroxy-buty-1-ynyl)-phenyl)-[1, 10]phenanthroline}ruthenium(II)bis(hexafluoro-phosphate) (7b), were synthesized under mild conditions. The former showed relative fluorescence intensity changes between fully oxygenated and fully deoxygenated atmospheres, while the latter showed a linear fluorescence intensity response between pH 6 and 13.

Graphical abstractThe phenanthroline derivatives, which have alkynyl groups, were synthesized by palladium-catalyzed, Sonogashira cross-coupling reaction. Their ruthenium complex 7a and 7b were synthesized under mild conditions. The former showed relative fluorescence intensity changes between fully oxygenated and fully deoxygenated atmospheres, while the latter showed a linear fluorescence intensity response between pH 6 and 13.Figure optionsDownload full-size imageDownload as PowerPoint slide