Proton Affinities and Photoelectron Spectra of Phenylalanine and N-Methyl- and N,N-Dimethylphenylalanine. Correlation of Lone Pair Ionization Energies with Proton Affinities and Implications for N-Methylation as a Method to Effect Site Specific Protonation of Peptides

1994 ◽  
Vol 116 (12) ◽  
pp. 5257-5264 ◽  
Author(s):  
Sherrie Campbell ◽  
Elaine M. Marzluff ◽  
M. T. Rodgers ◽  
J. L. Beauchamp ◽  
Margaret E. Rempe ◽  
...  
Keyword(s):  
Lone Pair ◽  
Photoelectron Spectra ◽  
Proton Affinities ◽  
Site Specific ◽  
Ionization Energies ◽  
Effect Site ◽  
Pair Ionization

Photoelectron Spectroscopy of Heterocycles. Phenyloxiranes

1984 ◽  
Vol 39 (12) ◽  
pp. 1230-1234 ◽  
Author(s):  
H. Güsten ◽  
L. Klasinc ◽  
I. Novak ◽  
M. Sanjek
Keyword(s):  
Double Bond ◽  
Ethylene Oxide ◽  
Photoelectron Spectroscopy ◽  
Lone Pair ◽  
Photoelectron Spectra ◽  
Ionization Energies ◽  
Perpendicular Orientation ◽  
Trans Stilbene ◽  
Oxygen Lone Pair

The Hel photoelectron spectra of 2-phenyloxirane, 2,2-diphenyloxirane, trans-2.3-diphenyloxirane, 2,2,3-triphenyloxirane, and 2,2,3,3-tetraphenyloxirane are reported. Comparison with the spectra of ethylene oxide (oxirane), benzene, and the following phenylethenes-styrene (1). I,1-diphenylethene (2), cis-stilbene (3), trans-stilbene (4), triphenylethene (5), and tetraphenylethene (6) - allowed to assign the lower ionization energies of the phenyloxiranes. Splitting of the lowest energy benzene π-orbitals is qualitatively the same in both classes of compounds. Because of the perpendicular orientation of the oxygen lone-pair in comparison to the π-electrons of the ethylene double bond this splitting is considerably smaller in phenyloxiranes.

The Hei and HeH Photoelectron Spectra of [Fe*?3-C3H5(CO)3X] and [Fe^3-C4H7 (CO)3X] (X = Cl, Br, I) and [CoC3H5(CO)3]

1982 ◽  
Vol 37 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Jaap N. Louwen ◽  
Jaap Hart ◽  
Derk J. Stufkens ◽  
Ad Oskam
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Lone Pair ◽  
Iron Complexes ◽  
Photoelectron Spectra ◽  
Pair Type ◽  
Ionization Energies ◽  
Uv Photoelectron Spectroscopy

Abstract By means of UV photoelectron spectroscopy (UPS) the electronic structures of [Feη3.C3H5(CO)3X], [Feη3-(2-CH3C3H4)(CO)3X] (X = Cl, Br, I) and [Co(C3H5)(CO)3] have been studied. Detailed assignments are possible and surprisingly low ionization energies (as low as 8.19 eV) are found for iodine lone pair type Orbitals. From the spectra a large difference in π backbonding is found between the cobalt and iron complexes

Photoelectron Spectroscopic Studies of Piperidine and its N-Halo Derivatives

1979 ◽  
Vol 32 (3) ◽  
pp. 475 ◽  
Author(s):  
T Gan ◽  
JB Peel
Keyword(s):  
Lone Pair ◽  
Spectroscopic Studies ◽  
Resonance Interaction ◽  
Photoelectron Spectra ◽  
Ionization Energies ◽  
Nitrogen Lone Pair

The HeI photoelectron spectra of N-chloropiperidine and N-bromopiperidine have been measured and compared with that of piperidine. The ionization energies associated with the nitrogen lone- pair and halogen non-bonding electrons indicate that there is considerably less nN-nx resonance interaction than in the smaller halo amines. HeII studies show that the halogen character is localized in both the N-halopiperidines with most ionization energies showing simple inductive shifts resulting from halogenation.

scholarly journals Ionization potentials of nitriles — Photoelectron spectra of succinonitrile and glutaronitrile

2006 ◽  
Vol 84 (9) ◽  
pp. 1124-1131 ◽  
Author(s):  
Heidi M Muchall ◽  
Nick H Werstiuk
Keyword(s):  
Energy Region ◽  
Photoelectron Spectrum ◽  
Lone Pair ◽  
Low Energy ◽  
Ionization Potentials ◽  
Photoelectron Spectra ◽  
Proton Affinities ◽  
Nitrogen Lone Pair ◽  
D Model ◽  
Highest Occupied Molecular Orbitals

The He(I) photoelectron spectra of succinonitrile (1) and glutaronitrile (2), both with extensive overlap of ionization bands in the low-energy region, are reported. To assign ionizations, we studied the conformational behaviour and resulting ionization energy dependence of 1 and 2 computationally with the B3LYP/6-31+G(d) model chemistry based on the fact that it reliably reproduces the ionization potentials of eleven mono- and di-nitriles, both saturated and unsaturated. The correlation of proton affinities with observed ionization potentials of 1, 2, and malononitrile establishes the orbital sequence of four C≡N π orbitals followed by two nitrogen lone pair orbitals as the highest occupied molecular orbitals for all three compounds.Key words: photoelectron spectrum, ionization potential, conformational dependence, nitrile, DFT.

The Photoelectron Spectra of the N-Chloro and N-Bromo Derivatives of Dimethylamine

1979 ◽  
Vol 32 (4) ◽  
pp. 719 ◽  
Author(s):  
F Carnovale ◽  
T Gan ◽  
JB Peel
Keyword(s):  
Energy Range ◽  
Molecular Orbital ◽  
Ionization Energy ◽  
Lone Pair ◽  
Photoelectron Spectra ◽  
Molecular Orbital Calculations ◽  
Ionization Energies ◽  
Resonance Effects ◽  
Derivatives Of ◽  
Lone Pair Interactions

The He I and He II spectra obtained for chlorodimethylamine (CH3)2NCl, and bromodimethylamine (CH3)2NBr, complete the study of the N-chloro and N-bromo derivatives of the small amines. The valence photoelectron spectra are interpreted with the aid of SPINDO molecular orbital calculations. Trends in the observed ionization energies for both series of small halo amines are described in terms of variations in inductive and resonance effects, the latter particularly concerning the nN/nx lone-pair interactions observed in the low ionization energy range.

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