Ferrocenyl−Naphthalimide Donor−Acceptor Dyads with Aromatic Spacer Groups

Abstract

The preparation and characterization of a series of dyads containing ferrocene donor and naphthalimide acceptor units, separated by aromatic spacer groups, are reported. The compounds contain a ferrocene-ethenyl spacer component linked to the 4-position of a naphthalimide by an ethynyl bridge, Fc−CH═CH−spacer−C≡C−naphthalimide (Fc = ferrocenyl), where the spacers are 1,4-phenyl, 4,4′-biphenyl, and 9,10-anthryl. Precursors to the dyad systems, halo-spacer−C≡C−naphthalimide, are also characterized where the halo-spacers are 1-bromophenyl, 4-bromobiphenyl, and 9-iodoanthryl. Various synthetic strategies are examined, with attachment of the spacer to 4-ethynylnaphthalimide followed by reaction with ethenylferrocene proving the most effective route. Crystal structures of the donor−spacer−acceptor (D−S−A) compound (E)-1-ethenylferrocenyl-4-(4-ethynyl-N-methyl-1,8-naphthalimide)benzene (7) and the precursor compounds (E)-4-bromo-4′-(ethenylferrocenyl)biphenyl (2) and 4-ethynyl-4′-(4-ethynyl-N-methyl-1,8-naphthal...