Synthesis, characterization and photophysical properties of a melamine-mediated hydrogen-bound phthalocyanine-perylenediimide assembly

The synthesis and supramolecular organization of a phthalocyanine 3 functionalized with a melamine moiety is described. 3 self-assembles in solution to form dimeric species - driven by double hydrogen-bonding between the aromatic amine functionality that is directly attached to the phthalocyanine ring and the melamine pyridinic nitrogens. In the presence of perylenediimide 2 , endowed with a complementary tritopic functionality, electron donor-acceptor assembly Pc-PDI (3) 2 22222·2 is spontaneously formed. (3) 2 22222·2 consists of two phthalocyanines of type 3 and a perylenediimide 2 , connected via triple hydrogen bonding between the melamine and the complementary unsubstituted imido functions. Electronic interactions between 2 and 3 in (3) 2 22222·2 give rise, upon selective photoexcitation of 2 , to an intramolecular electron transfer, affording a several nanosecond lived PDI&z.rad; − /H 2 Pc&z.rad; + species, while photoexcitation of 3 is only followed by an ordinary intersystem crossing. A melamine serves as the linker to hydrogen-bind a phthalocyanine with a perylenediimide for generating a long-lived radical ion pair state.