2,2'-Biquinoline2,2′-Biquinoline is an organic compound with the formula 2. It is one of several biquinolines. It is prepared by reductive coupling of 2-chloroquinoline. It is a colorimetric indicator for organolithium compounds.Ligand properties2,2′-Biquinoline is a bidentate ligand. Unlike the related complexes of 2,2′-bipyridine, the metal does not typically occupy the plane of the biquinoline.