We report a bottom-up approach for the fabrication of metallo-porphyrin compounds and nanoarchitectures in two dimensions. Scanning tunneling microscopy and tunneling spectroscopy observations elucidate the interaction of highly regular porphyrin layers self-assembled on a Ag(111) surface with iron monomers supplied by an atomic beam. The Fe is shown to be incorporated selectively in the porphyrin macrocycle whereby the template structure is strictly preserved. The immobilization of the molecular reactants allows the identification of single metalation events in a novel reaction scheme. Because the template layers provide extended arrays of reaction sites, superlattices of coordinatively unsaturated and magnetically active metal centers are obtained. This approach offers novel pathways to realize metallo-porphyrin compounds, low-dimensional metal-organic architectures and patterned surfaces which cannot be achieved by conventional means.

The electronic structure of isolated bis(phthalocyaninato) terbium(III) molecules, a novel single-molecular-magnet (SMM), supported on the Cu(111) surface has been characterized by density functional theory and scanning tunneling spectroscopy. These studies reveal that the interaction with the metal surface preserves both the molecular structure and the large spin magnetic moment of the metal center. The 4f electron states are not perturbed by the adsorption while a strong molecular/metal interaction can induce the suppression of the minor spin contribution delocalized over the molecular ligands. The calculations show that the inherent spin magnetic moment of the molecule is only weakly affected by the interaction with the surface and suggest that the SMM character might be preserved.The miniaturization of information storage devices drives the search for new nanoscale magnetic materials. Single molecular magnets (SMMs) formed by metal-organic complexes are very promising candidates as their large spin ground-state and large magnetic anisotropy are characteristics of each isolated molecule.1 Moreover, these systems provide a natural playground to explore magnetism at the nanoscale. Their future technological applications, such as quantum computing and high-density magnetic storage devices, are presently hampered by the difficulty of adsorbing SMMs onto surfaces and, quite importantly, by the lack of understanding on whether their magnetic properties are modified upon adsorption. In particular, the nonapplicability of conventional techniques, which allow an in-vacuum deposition, has so far hindered the systematic study of individual molecular magnets on surfaces. Solution-based deposition techniques including drop casting, 2,3 Langmuir-Blodgett, 4 microcontact printing, 5 covalent Au-S attaching, 6 and surface functionalization 7 have been successfully used to transfer molecules to surfaces but the magnetic properties of the adsorbed molecules have so far not been demonstrated. 3 This has tentatively been assigned to an induced local disorder caused by the used deposition techniques or by the coupling to the surface. 8 In this letter, we describe the structural, magnetic and electronic properties of a surface-supported SMM by combining scanning tunneling microscopy (STM) and spectroscopy (STS) with numerical simulations based on density functional theory (DFT). Topographic images and conductance maps of isolated SMM (namely bis(phthalocyaninato) terbium(III)) achieved at several energies confirm that the molecular structure is unchanged by the interaction with the surface. The Tb-4f electron states, which are responsible for the large magnetic moment of the molecular magnet, are little affected by molecular adsorption on the metal surface. Thus, it can be expected that the SMM character of the surface supported bis(phthalocyaninato) terbium(III) (abbreviated by TbPc2) molecules is preserved.TbPc2 molecules represent the first example of mononuclear metal complexes behaving as SMMs (i.e., showing large mag...

The experimental and theoretical study of the electron spin dynamics in the anionic form of a single-ion molecule magnet (SIMM), the bis-phthalocyaninato terbium (III) molecule [Pc(2)Tb](-)[TBA](+), has been addressed by means of solid state (1)H NMR spectroscopy. The magnetic properties of the caged Tb(3+) metal center were investigated in a series of diamagnetically diluted preparations, where the excess of tetrabutylamonium bromide ([TBA]Br)(n) salt was used as diamagnetic matrix complement. We found that a high temperature activated spin dynamics characterizes the systems, which involved phonon-assisted transitions among the crystal field levels in qualitative agreements with literature results. However, the activation barriers in these processes range from 641 cm(-1) for the diamagnetically diluted samples to 584 cm(-1) for those undiluted; thus, they exhibit barriers 2-3 times larger than witnessed in earlier (230 cm(-1)) reports (e.g., Ishikawa, N.; Sugita, M.; Ishikawa, T.; Koshihara, S.; Kaizu, Y. J. Am. Chem. Soc. 2003, 125, 8694-8695). At cryogenic temperatures, fluctuations are driven by tunneling processes between the m = +6 and -6 low-energy levels. We found that the barrier Delta and the tunneling rates change from sample to sample and especially the diamagnetically diluted [Pc(2)Tb](-) molecules appear affected by the sample's magneto/thermal history. These observations emphasize that matrix arrangements around [Pc(2)Tb](-) can appreciably alter the splitting of the crystal field levels, its symmetry, and hence, the spin dynamics. Therefore, understanding how small differences in molecular surroundings (as for instance occurring by depositing on surfaces) can trigger substantial modifications in the SIMM property is of utmost importance for the effective operation of such molecules for single-molecule data storage, for example.