Pei, J.;* Wang, J.-L.; Cao, X.-Y.; Zhou, X.-H.; Zhang, W.-B. Star-Shaped Polycyclic Aromatics Based on Oligothiophenes-Functionalized Truxene: Synthesis, Properties and Facile Emissive Wavelength Tuning, J. Am. Chem. Soc. 2003, 125, 9944-9945. [Link] [PDF]

Abstract
A facile approach to soluble star-shaped oligothiophene-functionalized polycyclic aromatics based on truxene is developed in this Communication. The Suzuki coupling reactions afford the thiophene-containing polycyclic aromatics with long branches (about 2.1 nm length from the heart to the periphery) from truxene precursor with excellent yields. The unsubstituted α-positions of thiophene rings allow for efficient halogenation and for further functionalization. The investigation of proton NMR spectra indicates that the hexahexyl groups efficiently prevent the self-association through the arene−arene π-stacking. Chemical shifts belonging to methylene groups move more upfield than do those of methyl groups. These chemical shift values (about 0.5−0.6 ppm) are quite lower than those of normal methyl and methylene groups. We also prepare a dendritic hyperbranched polymer P1 through FeCl3 mediated oxidative polymerizations. The photophysical properties of all compounds possessing good symmetry are investigated by UV−vis and emission measurement.