X-Ray Crystal Structures and Photophysical Properties of New Conjugated Oligoquinolines

摘要

The synthesis, characterization, X-ray crystal structures, and photophysical properties of two conjugated oligoquinolines, 2,2'-bis(4- phenylquinoline)-1,4-phenylene (2a) and 2,2-bis(4-phenylquinoline) -4,4'-biphenylene (2b), are reported. Both 2a and 2b crystallized in a monoclinic lattice with different unit cell parameters and space groups.The X-ray crystal structures reveal that 2a exhibits intermolecular face-to-face pi-pi stacking whereas 2b manifests edge-to-face pi-pi stacking. The dilute solution and solid state optical absorption and emission spectra of 2b were red-shifted from those of 2a because of the greater degrees of pi-electron delocalization and intramolecular charge transfer in 2b compared to 2a. The strongly Stokes shifted solid state emission bands of both oligomers from their absorption bands are attributed to excimer formation. These conjugated oligoquinolines with known X- ray crystal structures are excellent model systems for elucidating the structure and properties of polyquinolines and may also find device applications as n-type semiconductors.