Nanosized rigid π-conjugated molecular heterojunctions with multi[60]fullerenes: Facile synthesis and photophysical properties

A series of large, rigid, new, well-defined, D-π-B-A compounds with three chromophores (truxene moieties at the core, conjugated oligothiophenes as the branch bridges, and [60]pyrrolidinofullerene (C₆₀) segments as the end-capped groups) have been facilely developed in this contribution. Oligothiophene-functionalized truxene derivatives 1-29 are prepared by the Suzuki, the Sonogashira, and the Negishi cross-coupling reactions catalyzed by Pd(PPh₃)₄ as well as the McMurry reaction, respectively. The 1,3-dipolar cycloaddition of the oligomers with C₆₀ and N-methylglycine yields a new family of star-shaped D-π-B-A derivatives end-capped with pyrrolidinofullerene moieties as the active materials for photovoltaic devices in which one, two, three, or four C₆₀ moieties are allocated at the peripheral position of well-defined compounds, respectively. We also investigate the UV-vis and photoluminescence behaviors of these pyrrolidinofullerene-functionalized derivatives. The emission is obviously quenched after the inducement of the C₆₀ moieties. We also observe that the emission intensity is decreased with the increase in the number of C₆₀ moieties.