X-ray crystal structures and photophysical properties of new conjugated oligoquinolines

Two new conjugated oligoquinolines, 2,2'-bis(4-phenylquinoline)-1,4-phenyle ne (2a) and 2,2'-bis(4-phenylquinoline)-4,4'-biphenylene (2b), were synthes ized and found to crystallize in a monoclinic lattice with different unit c ell, parameters and space groups. Single-crystal X-ray crystal structures r evealed intermolecular face-to-face (2a) and edge-to-face (2b) pi-pi stacki ng which influenced the solid state photophysical properties. These conjuga ted oligoquinolines with known X-ray crystal structures are excellent model systems for elucidating the structures and properties of polyquinolines an d may also find device applications as n-type semiconductors.