Abstract
Extended π-conjugated systems are often insoluble, and their aggregation manner greatly affects their absorption spectra. This study produced a planar, soluble, and nonaggregated hexarylene-bisimide (HB) with appropriate substituents. The single-crystal X-ray structure of HB confirmed the planar molecular structure with small twist angles and the dimerization behavior of HB in the solid state. The concentration-dependent (1)H NMR experiments in CDCl(3) indicated that the association constant K(dimer) is 4.6 × 10(3) M(-1) at 298 K and ΔG(dimer) (298 K) = -20.8 kJ mol(-1). The longest absorption of HB at the monomeric state exhibits a sharp and intense peak at 921 nm (ε = 230,000 M(-1) cm(-1), full width at half-maximum = 718 cm(-1)) in toluene. 75% of the absorption of HB above 400 nm appears in the near-infrared region, thus giving a practically colorless solution. Magnetic circular dichroism spectra of a series of oligorylene-bisimides reveal the predominant contribution of the linear polyene-like conjugation over the annulene-like conjugation for larger [n]oligorylene-bisimides.