X-ray photoelectron spectroscopy- and surface plasmon resonance-detected photo release of photolabile protecting groups from nucleoside self-assembled monolayers on gold surfaces.

The formation of self-assembled monolayers (SAMs) on gold by 2-(5-iodo-2-nitrophenyl) propoxycarbonyl (I-NPPOC)-protected thymidine with an attached mercaptohexyl succinate linker and the kinetics of photochemical release of the I-NPPOC group were monitored using X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance (SPR) detection. In the XPS spectra, the iodine peaks allowed for specific and accurate monitoring of the presence and loss of I-NPPOC groups on the surface. In the SPR experiment, the overall signal change on photoillumination is in accord with a theoretical estimation of the density of I-NPPOC groups in a dense monolayer. The kinetics roughly follow a biexponential time dependence with two very different time constants, corresponding to photochemical quantum yields of 0.22 and 0.0032, respectively.

A comparative study on the deposition of Mn12 single molecule magnets on the Au(111) surface.

Different approaches to the deposition of Mn(12) single molecule magnets on the Au(111) surface and their characterization by a broad variety of techniques are investigated with respect to their suitability for a profound corroboration of the integrity of the Mn(12) core. In this context, the most recent improvements in the experimental approaches are presented and the latest results on the electronic properties of Mn(12) are linked to each other. The results confirm the high instability of Mn(12) single molecule magnets on surfaces and reveal the need for an amendment of the requirements to define the structural integrity of Mn(12) molecules on surfaces.

Single-molecule magnets: a new approach to investigate the electronic structure of Mn12 molecules by scanning tunneling spectroscopy.

A new approach to the deposition of Mn12 single-molecule magnet monolayers on the functionalized Au(111) surface optimized for the investigation by means of scanning tunneling spectroscopy was developed. To demonstrate this method, the new Mn12 complex [Mn12O12(O2CC6H4F)16(EtOH)4].4.4CHCl3 was synthesized and characterized. In MALDI-TOF mass spectra the isotopic distribution of the molecular ion peak of the latter complex was revealed. The complex was grafted to Au(111) surfaces via two different short conducting linker molecules. The Mn12 molecules deposited on the functionalized surface were characterized by means of scanning tunneling microscopy showing homogeneous monolayers of highest quality. Scanning tunneling spectroscopy measurements over a wider energy range compared with previous results could be performed because of the optimized Au(111) surface functionalization. Furthermore, the results substantiate the general suitability of short acidic linker molecules for the preparation of Mn12 monolayers via ligand exchange and represent a crucial step toward addressing the magnetic properties of individual Mn12 single-molecule magnets.