Part 1.N-(m-(3-(trifluoromethyl)diazirine-3-yl)phenyl)-4-maleimido-butyramide (MAD) on silicon, silicon nitride and diamond

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS) are used to characterize the grafting of the reagent N-(m-(3-(trifluoromethyl)diazirine-3-yl)phenyl)-4-maleimido-butyramide (MAD) to various substrates: silicon, silicon nitride and diamond. MAD carries a maleimide function for thermochemical modification of thiolated molecules and a diazirine function that is lost during light activation (350 nm light). Photoactivation leads to carbene-mediated grafting to solid supports. X-ray photoelectron spectroscopy atomic constituents and chemical shifts, as well as ToF-SIMS molecular peaks and characteristic fragments of the photoimmobilized molecule, are identified. Extended interpretation of surface analysis data suggests that diamond is the substrate with the highest MAD grafting efficiency and that the formation of C-O bonds upon diazirine photoactivation is involved. The difference in grafting extent for the three substrates leads to the conclusion that other reaction sites could be involved but they are not identified.