Surface chemistry of the iron tetraazamacrocycle on the aminopropyl‐modified surface of oxidized n‐Si(100) by AFM and XPS

Abstract

The structure and formation mechanisms of 3-aminopropyltrimethoxysilane (3-APTS) films deposited on wet-chemically grown silicon dioxide over n-Si(100) wafer have been examined systematically using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The asymmetric N 1s XPS spectrum for the anchored 3-APTS was fitted for -NH 2 (399.6 ± 0.3 eV) and -NH 3 + (401.1 ± 0.3 eV). Rougher surfaces are obtained by deposition from toluene solutions than from the gaseous phase. Over the 3-APTS layer was deposited the [FeTIM(CH 3 CN) 2 ]2+ complex, where TIM is 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene. The adsorption occurs by acetonitrile replacement for the-NH 2 -grafted group with the equatorial plane parallel to the organomodified surface. Once FeTIM can bind a CO, NO or N-heterocycle, a built-on Si wafer sensor device could be envisaged for these molecules.

XPS analysis of electronic density of iron tetraazamacrocycle through Fe 2p binding energies on the 3‐imidazolilpropyl‐modified surface of oxidized n‐Si(100)

“…3(b)), which was fitted for two components at 399.7 and 401.9 eV and assigned to non-protonated and protonated imidazole groups, respectively. The protonation could be due to the interaction with the surface silanol groups, 3,9 as they have pK a values in the range of 3.67 to 4.82, and 6.37 to 7.01 10 and alkylimidazole has a pK a value around 7.5.…”

“…The silicon surface was previously treated according to the procedure reported 3 in order to obtain smooth and clean surfaces of SiO 2 /Si. Gold-covered surfaces were obtained as previously reported.…”

“…3 The modified plates were washed ultrasonically with acetonitrile to remove the FeTIM physically adsorbed on the surface.…”

“…The spectra were charge-corrected and the chemical compositions of the films were verified as previously described. 3,7 The accuracy for Fe 2p in the FeTIM complex is š15 % for the atomic ratios and š0.3 eV for the binding energy, and for other elements is š10 % and š0.2 eV, respectively.…”

Conformações distorcida e planar do anel porfirínico em complexos e hemoproteínas: propriedades físico-químicas e implicações espectroscópicas

“…Esta estabilidade, juntamente com a conhecida versatilidade dos sistemas macrocíclicos, além da evidente relevância biológica, tem motivado várias pesquisas desses compostos como protótipos em modificação de superfícies (filmes finos) 1 , confecção de sistemas supramoleculares (supermoléculas) 2,3 , reconstituição de hemoproteínas 4 e biomimetismo de hemoproteínas por meio de complexos modelos 5 , entre outras aplicações. Vale lembrar que a química dos ligantes macrocíclicos recebeu especial destaque com a outorga do prêmio Nobel de 1987 a Lehn, Pedersen e Cram [6][7][8] .…”