Alternative Synthesis of C60‐Diphenylaminofluorene Derivatives for Nonlinear Photonic Applications: Method of Preparation and Characterization

An alternative synthetic route for the preparation of key intermediate synthons 7‐α‐bromoacetyl‐2‐diphenylaminofluorene (α‐BrDPAF‐H) and 7‐α‐bromoacetyl‐9,9‐dialkyl‐2‐diphenylaminofluorene (α‐BrDPAF‐C_n) was demonstrated. The latter reactions involved the first step of dialkylation of 2‐bromofluorene at C₉ position of the fluorene moiety, the second step of a diphenylamino group attachment at C₂ position of the resulting dialkylfluorene, and the third step of Friedel‐Craft acylation of α‐bromoacetyl group at C₇ position of dialkylated diphenylaminofluorene. From the intermediates α‐BrDPAF‐H and α‐BrDPAF‐C_n, a series of C₆₀‐keto‐DPAF nanostructures, such as the fullerene monoadducts C₆₀(>DPAF‐H) and C₆₀(>DPAF‐C_n), where n is 2, 4, or 10, were synthesized in a reasonable yield. Molecular mass ions of the dyads C₆₀(>DPAF‐H), C₆₀(>DPAF‐C₂), C₆₀(>DPAF‐C₄), and C₆₀(>DPAF‐C₁₀) were clearly detected in positive ion matrix‐assisted laser desorption ionization mass spectrum (MALDI–MS) that confirmed the composition mass of each compound synthesized.