Fig. 1. Chemical formulae of the molecules investigated. Hexa-peri-hexabenzocoronenes (HBCs) bearing six anthraquinone (AQ) functions 1, an amino group 2 and a carboxylic acid group 3, respectively, and 9,10-dimethoxyanthracene (DMA) 4.

Fig. 2. STM current images of (a) mixture of 1 and 4; clearly visible are the HBC cores (bright circular spots) and the charge transfer complexes between AQ and DMA (smaller spots on zig-zag-row); (b) 2 exhibiting hexagonal arrangement, (c) 3 exhibiting hexagonally packed domains and areas with a dimer structure and (d) 2 + 3 forming the same structures as 3. Tunneling parameters were (a) sample bias U_t = −1.2 V and average tunneling current I_t = 270 pA (b) U_t = −1.0 V and I_t = 100 pA (c) U_t = −1.2 V and I_t = 100 pA and (d) U_t = −0.8 V and I_t = 50 pA.

Fig. 3. (a) I–Vs through HBC-cores in mixtures of 1 and 4 measured in domains where charge transfer complexes between 4 and the AQ-moieties in 1 are coadsorbed (full circles) and in domains where no complexes are present (open triangles). (b) I–Vs through HBC-cores in monolayers of 2 (open triangles), 3 (open squares) and 2 + 3 (full triangles). Tunneling parameters before switching off the feedback loop were sample bias U_s = −1.4 V and average tunneling current I_t = 500 pA.