Pyrrole-Embedded Linear and Helical Graphene Nanoribbons.

Linear and helical graphene nanoribbons (L-PyGNR and H-PyGNR) bearing electron-rich pyrrole units have been synthesized by using the photochemical cyclodehydrochlorination (CDHC) reaction. The pyrrole units in the polymer backbone make the polymer electron-rich with moderate bandgap values and relatively high HOMO energy levels. The planarization of the pyrrole unit through cyclization yields a bandgap value almost 0.5 eV lower than that measured for polypyrrole. Conductivity values in the thin film up to 0.12 S/cm were measured for the chemically oxidized L-PyGNR (four-point method). Both GNRs showed excellent fluorescence sensing properties for TNT in solution with KSV values up to 6.4 × 106 M-1.