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

Two new conjugated oligoquinolines, 2,2'-bis(4-phenylquinoline)-1,4-phenylene (2a) and 2,2'-bis(4-phenylquinoline)-4,4'-biphenylene (2b), were synthesized and found to crystallize in a monoclinic lattice with different unit cell, parameters and space groups. Single-crystal X-ray crystal structures revealed intermolecular face-to-face (2a) and edge-to-face (2b) pi-pi stacking which influenced the solid state photophysical properties. These conjugated oligoquinolines with known X-ray crystal structures are excellent model systems for elucidating the structures and properties of polyquinolines and may also find device applications as n-type semiconductors.