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[Co(L)4]A8; STM; Graphite; SBA; GK; CP
Abstract:
Self-assembled tetranuclear complexes of metallogrid type [Co4(L4)](PF6), R1=CH3, R2=H (compound 1) and [Co4(L4)](AsF6), R1=H, R2=CH3 (compound 2), L=4,6-bis(611R1-21,21-bipyrid-6-yl)-2-R2-pyrimidine were adsorbed onto highly oriented pyrolitic graphite and studied by STM. Monodomains of a regularly packed layer of adsorbed molecules with areas up to 0.5 μm2 were observed. Sample 1 showed a molecular pattern with nearly orthogonal periodicities of 1.35 nm×2.6 nm consisted with the size of the 2×2 Co-grid oriented normally to the surface. A periodicity of 2.5 nm×2.4 nm was found for complex 2 consistent with orientation of the grid parallel to the surface. Holes in the monolayer, which were formed by removal of a particular complex by STM, were observed to diffuse along the surface with a diffusion coefficient of D=5.2×10−16 cm2/s. The free energy of the diffusion activation were found to be ΔFd=730 meV.
