2D-Structures of quadruple hydrogen bonded oligo(p-phenylenevinylene)s on graphite:: Self-assembly behavior and expression of chirality

The two-dimensional pattern formation of chiral oligo(p-phenylenevinylene) derivatives of different lengths containing a self-complementary hydrogen bonding motif at the liquid/solid interface has been investigated and compared using scanning tunneling microscopy. Hydrogen bonding leads to dimer formation and the chirality of the molecules is expressed at the level of packing and orientation of the dimers with respect to the substrate symmetry. Differences in expression of molecular chirality are observed as a function of molecular length and the number of stereocenters they carry. Mixing of oligomers of different length does not lead to phase separation, but to the formation of heterodimers, stressing the important role of hydrogen bonding in the self-assembly process in both solution and at the liquid/solid interface.