Fig. 5: Oligomerization on h-BN/Cu(111) after deposition of 1 onto the surface held at 500 K.
From: Polycyclic aromatic chains on metals and insulating layers by repetitive [3+2] cycloadditions
a STM overview image shows coupled molecular units, analogous to the cycloaddition products observed on Au(111) and Ag(111). Unidentified species are also observed, cf. image’s center and Table 1. b, c Close-up STM images reveal the formation of chains of up to eight monomer units. Non-covalent aggregation with antiparallel alignment of the –CN dipoles of a dimer and an octamer is marked by a red dashed circle in b. d STM image of oligomer chains. e After application of a voltage pulse (VS = −2.5 V, I = 100 pA, t = 1 s) at the position marked with a yellow cross in d a shift of the positions of the chains is observed. The chains remain intact and each chain is shifted as a whole. The positions of the chains before the voltage pulse are marked with white dashed traces (data in a, c–e recorded after post-annealing the sample to 580 K). Scan parameters: (a) VS = 1.10 V, I = 50 pA, (b) VS = 0.66 V, I = 60 pA, (c) VS = 1.0 V, I = 50 pA; (d), (e) VS = 1.7 V, I = 24 pA.
