Photochemistry of N-Methylformamide: Matrix Isolation and Nonadiabatic Dynamics

The photochemistry of N-methylformamide (MF) is elucidated by investigating its photodissociation products generated by UV irradiation (248 nm) in an argon matrix (10 K). We find that, starting from trans-MF, prolonged irradiation produces cis-MF, CH3NH2 and CO fragments as major products. Another photoproduct is identified as methylformimidic acid (FIA). Nonadiabatic dynamics simulations starting from both MF conformers revealed that the internal conversion occurs within 1 ps through a C—N dissociation channel. The major product is a weakly bound complex between CH3NH and HCO radicals. This complex owes its existence to the cage effect of the matrix which allows for H-transfer reactions and recombination. By identifying the primary photoisomerization and photodissociation pathways of MF, we gain new insights into the photochemistry of peptide bonds in general, which is a prerequisite for a better understanding of the effect of UV irradiation on living systems

Polymer Brushes Exhibiting Versatile Supramolecular Interactions Grown by Nitroxide-Mediated Polymerization and Structured via Microcontact Chemistry

Functionalization of metal, glass, and semiconductor substrates with polymers and nanoparticles is a key challenge for surface-based material science. Such substrates have the potential to find widespread application in optical and electronic devices, microarrays, and materials for information storage. We report site-specific immobilization of nitroxide-mediated polymerization initiators via microcontact chemistry employing thiol–ene click chemistry on glass-supported alkene-terminated self-assembled monolayers. The polymer initiator covered substrates are used for preparation of poly­(styrene) and poly­(acrylate) brushes with defined and tunable brush thicknesses. Brush thickness dependent site-specific protein adsorption of streptavidin and concanavalin A on structured polystyrene brushes is reported. Poly­(styrene) brushes with a thickness of 40 nm or larger showed protein repellence whereas brushes below 15 nm thickness reveal protein adhesive properties. We also disclose the site selective host–guest assisted immobilization of β-cyclodextrin-coated silica nanoparticles and the tethering of liposomes modified with amphiphilic β-cyclodextrin onto adamantane-functionalized poly­(acrylate) brushes. Selective immobilization of these supramolecular colloids via the multivalent hydrophobic inclusion complex of β-cyclodextrin and adamantane can be readily verified by fluorescence microscopy imaging, atomic force microscopy, and quartz crystal microbalance with dissipation monitoring

Complexes of nitric oxide with water and imidazole

R.C-O and R.S acknowledge a research fellowship from Universidad Autónoma de Madrid. E.S-G and K.B-R acknowledge Liebig and doctoral stipends, respectively, from the Fonds der Chemischen Industrie, Germany. E.S-G acknowledges the support of the Cluster of Excellence RESOLV (EXC 1069) and the Collaborative Research Center SFB 1093, both funded by the Deutsche Forschungsgemeinschaft. J.M.GV thanks MICINN (Project No. CTQ2010-12932) and AECID (Project No. A1/035856/11)