Adsorption geometry and core excitation spectra of three phenylpropene isomers on Cu(111)

Theoretical C 1s near edge x-ray absorption fine structure (NEXAFS) spectra for the C(9)H(10) isomers trans-methylstyrene, alpha-methylstyrene, and allylbenzene in gas phase and adsorbed at Cu(111) surfaces have been obtained from density functional theory calculations where adsorbate geometries were determined by corresponding total energy optimizations. The three species show characteristic differences in widths and peak shapes of the lowest C 1s-->pi(*) transitions which are explained by different coupling of the pi-electron system of the C(6) ring with that of the side chain in the molecules as well as by the existence of nonequivalent carbon centers. The adsorbed molecules bind only weakly with the substrate which makes the use of theoretical NEXAFS spectra of the oriented free molecules meaningful for an interpretation of experimental angle-resolved NEXAFS spectra of the adsorbate systems obtained in this work. However, a detailed quantitative account of relative peak intensities requires theoretical angle-resolved NEXAFS spectra of the complete adsorbate systems which have been evaluated within the surface cluster approach. The comparison with experiment yields almost perfect agreement and confirms the reliability of the calculated equilibrium geometries of the adsorbates. This can help to explain observed differences in the catalytic epoxidation of the three molecules on Cu(111) based on purely geometric considerations.     

Synthesis and characterization of a series of 1,x‐bis‐(4‐oxo‐3,4‐dihydro‐1,2,3‐benzotriazin‐3‐yl)alkanes

Reaction of isatoic anhydride with an alkanediamine in DMF solution under mild conditions affords excellent yields of the 1,x‐bis‐{(2‐aminobenzoyl‐)amino}alkanes ( 2a‐k ), which have been characterized by IR and NMR spectroscopy, high resolution mass spectrometry and elemental analysis. Diazotization of the bis‐{(2‐aminobenzoyl‐)‐amino}alkanes in aqueous solution gives high yields of the 1,x‐bis‐(4‐oxo‐3,4‐dihydro‐1,2,3‐benzotriazin‐3‐yl)alkanes ( 1a‐k ), whch have also been characterized by IR and NMR spectroscopy, high resolution mass spectrometry and elemental analysis. The alkanediamines employed are as follows: ethylene diamine, 1,3‐propanediamine, 1,2‐propanediamine, 2‐methyl‐1,2‐propanediamine, 2,2‐dimethyl‐1,3‐propanediamine, 2‐hydroxy‐1,3‐propanediamine, 1,4‐diaminobutane, 1,5‐diaminopentane, 1,3‐diaminopentane (DYTEK® EP diamine), 1,6‐diaminohexane and 1,7‐diaminoheptane. The alternative method of synthesis of the bis‐(4‐oxo‐3,4‐dihydro‐1,2,3‐benzotriazin‐3‐yl)alkanes ( 1 ) via the diazonium salt from methyl anthranilate was explored.