Two-Dimensional Molecular Grids on Mercury

We describe an electrochemical Langmuir-Blodgett (LB) trough for the synthesis and characterization of regular two-dimensional networks on a mercury surface. Two strategies were applied to the preparation of molecular grids on mercury. One was based on the mounting of lanthanum(III) bis(meso-tetrapyridylporphyrinate) sandwich anions (TPyP)2La- on mercury subphase and coupling it with hydroquinone derivatives as temporary, or “phantom”, couplers. These couplers provide a weak and reversible bridging of (TPyP)2La- connectors on mercury. As a result a highly ordered square grid is created prior to the introduction of the real sturdy couplers for the replacement of the “phantom” ones. In the other strategy advantage has been taken of the high affinity of divalent sulfur compounds for mercury ions. The trigonal connectors, 1,3,5-triscarboranylbenzenes with attached alkylthioether chains, are firmly adsorbed on mercury at positive potentials and presumably form a hexagonal grid due to their mutual coupling through mercury ions.