When aromatic self-assembled monolayers (SAMs) are electron-irradiated, intermolecular cross-links are formed and the SAMs transform into carbon nanosheets with molecular thickness. These nanosheets have a very high mechanical stability and can withstand temperatures above 1000 K. In this report, we investigate the electron induced cross-linking of 1,1'-biphenyl-4-thiol (BPT) SAMs on gold by combining X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (NEXAFS), thermal desorption spectroscopy (TDS), and UV photoelectron spectroscopy (UPS). The experimental data were acquired as a function of electron dose and temperature and compared with quantum chemical calculations. Details of the intermolecular cross-linking, the microstructure of cross-linked films, and their structural transformations upon heating were obtained to derive a view of the mechanisms involved. Our analysis shows that room-temperature electron irradiation causes a lateral cross-linking via the formation of C-C linked phenyl species as well as a new sulfur species. The thermal stability of the BPT films increases with the electron dose and saturates at approximately 50 mC/cm2. Nevertheless, nonlinked fragments in the thermal desorption spectra indicate an incomplete cross-linking even at high doses, which can be attributed to steric reasons and quenching due to the reduced band gap of partially linked molecules. At temperatures above 800 K, all sulfur species are thermally desorbed, while the remaining film reveals an onset of carbonization.

Electron‐induced chemical lithography combined with self‐assembled monolayers and multivalent chelators for high‐affinity capturing of His‐tagged proteins are used to obtain specific, stable, highly parallel, and functional protein micro‐ and nanoarrays on solid substrates. The functionality of the generated large‐area protein arrays is shown in situ via specific, homogeneous, oriented and reversible immobilization of His6‐tagged 20S proteasome and fluorescence labelled His10‐tagged maltose binding proteins.

Extreme-UV interference lithography (EUV-IL) is applied to create chemical nanopatterns in self-assembled monolayers (SAMs) of 4'-nitro-1,1'-biphenyl-4-thiol (NBPT) on gold. X-ray photoelectron spectroscopy shows that EUV irradiation induces both the conversion of the terminal nitro groups of NBPT into amino groups and the lateral crosslinking of the underlying aromatic cores. Large-area ( approximately 2 mm(2)) nitro/amino chemical patterns with periods ranging from 2000 nm to 60 nm can be generated. Regions of pristine NBPT on the exposed samples are exchanged with protein-resistant thiol SAMs of polyethyleneglycol, resulting in the formation of molecular nanotemplates, which can serve as the basis of complex biomimetic surfaces.

An extremely high thermal stability of electron cross-linked biphenyl self-assembled monolayers (SAMs) is reported. The authors found that pristine biphenylthiol SAMs desorb at ∼400K from gold surfaces, which is induced by a breaking of C–S bonds. Despite of a similar bond cleavage in cross-linked SAMs, these remain on the surface up to 1000K, which is the highest temperature reported for a SAM. When patterns of pristine and cross-linked SAMs are heated, the pristine regions desorb, and the cross-linked regions remain on the surface. The authors show that this thermal desorption lithography can be utilized for the fabrication of molecular surface nanostructures.

No abstract