Polymorphism in porphyrin monolayers: the relation between adsorption configuration and molecular conformation.

Self-assembled monolayers of meso-5,10,15,20-tetrakis(undecyl)porphyrin copper(II) on a graphite/1-octanoic acid interface have been studied by Scanning Tunnelling Microscopy. Four distinct polymorphs were observed, varying in their unit cell size. Arrays of unit cells of the various polymorphs seamlessly connect to each other via shared unit cell vectors.

Little exchange at the liquid/solid interface: defect-mediated equilibration of physisorbed porphyrin monolayers.

The transition from low to high density 2D surface structures of copper porphyrins at a liquid/solid interface requires specific defects at which nearly all exchange of physisorbed molecules with those dissolved in the supernatant occurs.

Cooperative double deprotonation of bis(2-picolyl)amine leading to unexpected bimetallic mixed valence (M(-I), M(I)) rhodium and iridium complexes.

Cooperative reductive double deprotonation of the complex [Rh(I)(bpa)(cod)](+) ([4](+), bpa = PyCH(2)NHCH(2)Py) with one molar equivalent of base produces the bimetallic species [(cod)Rh(bpa-2H)Rh(cod)] (7), which displays a large Rh(-I),Rh(I) contribution to its electronic structure. The doubly deprotonated ligand in 7 hosts the two "Rh(cod)" fragments in two distinct compartments: a "square planar compartment" consisting of one of the Py donors and the central nitrogen donor and a "tetrahedral π-imine compartment" consisting of the other pyridine and an "imine C═N" donor. The formation of an "imine donor" in this process is the result of substantial electron transfer from the {bpa-2H}(2-) ligand to one of the rhodium centers to form the neutral imine ligand bpi (bpi = PyCH(2)N═CHPy).

Self-assembly of porphyrins on a single crystalline organic substrate.

Layers of a free base porphyrin have been deposited from n-heptane solution onto single crystalline potassium acid phthalate substrates and the self-assembled structures have been characterized by atomic force microscopy and X-ray diffraction. Depending on the concentration of the porphyrin solution, different anisotropic structures are found that are epitaxially related to the substrate, with the length axis parallel to the [001] direction of the (010) substrate surface. For undersaturated solutions, islands, cellular structures, and a hole pattern of monolayers of approximately 2.

Deprotonation induced ligand-to-metal electron transfer: synthesis of a mixed-valence Rh(-I,I) dinuclear compound and its reaction with dioxygen.

Treatment of bis(2-picolyl)amine (bpa) with [{Rh(nbd)(mu-OMe)}2] leads to the unexpected and unique redox asymmetric dinuclear Rh-I,Rh+I complex [{Rh(nbd)}2(bpa-2H)] (2) with a pi-coordinating imine bound to a tetrahedral low valent rhodate(-I). Mono-oxygenation of the deprotonated bpa ligand in 2 by O2 leads to the mononuclear carboxamido complex [Rh(nbd)(bpam-H)] (3) (bpam = N-(2-picolyl)picolinamide). The second O atom of O2 ends up as a hydroxo fragment in [{Rh(nbd)(mu-OH)}2].