A synthetic protocol for a novel family of symmetric polycyclic aromatics with a benzene or cyclooctatetraene (COT) ring as the core and alternant fused benzene and cyclopentadiene rings as branches has been developed. The TiCl4-promoted cyclizations construct both planar trimers and tubelike tetramers via the "in situ" generation of the benzene or COT skeleton. The structures of 6b, 7a, 7b, and 10 have been characterized by 1H and 13C NMR spectra and MALDI-TOF mass spectroscopy. These polycyclic aromatics also exhibit interesting optical properties.

A series of novel extended π-conjugated twin molecules based on 10,15-dihydro-5H-diindeno[1,2-r;1´,2´-c]fluorene (truxene) have been prepared via Pd(0)-catalyzed Suzuki coupling, Sonogashira coupling, and McMurry reactions, respectively. 9,9´-Spirobifluorenylene, ethynylene, and vinylene groups as the bridge are introduced to connect both truxene moieties to understand the effect of the large steric chromophores on the properties of the desired materials. The investigation of optical properties of TM1-3 by UV-vis and photoluminescent spectroscopy demonstrates that the optical properties of the twin molecules are strongly affected by the ð-linkages.

A convenient approach to a series of star-shaped

Two series of novel alternating polyfluorene copolymers containing 10,15-dihydro-5Hdiindeno[ 1,2-R;1