Diverse self-assembly in soluble oligoazaacenes: A microscopy study

The synthesis and morphologies of self-assembled aggregates of novel oligoazapentacene 2 and oligoazaheptacene 3 derivatives are reported. Double nucleophilic substitution on 2,3-dicyano-[Hj]-dibenzo-1,4,5,10- te1raazaanthracene 4 gives the corresponding dihydro-oligoacene derivatives, which were then N-alkylated using n-dodecyl bromide to yield self-assembling acene molecules. 2 and 3 self-assemble in solution, leading to a variety of aggregated structures including rolled-up sheets, foams, and fibrous structures reminiscent of organogels. These structures are of substantial interest because of their potential electronic properties and because individual fibers can be "exfoliated". Structures of the aggregates are discussed. Additionally, the crystal structure of precursor 4 is reported because it gives information regarding the intermolecular interactions (hydrogen bonding and intermolecular stacking) in similar compounds. Crystal data for 4: space group P2(1)/n, a = 9.3164(17) Å, b = 7.0649(13) Å, c = 23.684(4) Å, α = 90.00°, β = 99.945(3)°, γ = 90.00°, and V = 1535.4(5)ų.