title: Combined photoelectron, collision-induced dissociation, and computational studies of parent and fragment anions of N-paranitrophenylsulfonylalanine and N-paranitrophenylalanine.
abstract: After synthesizing the compounds N-paranitrophenylsulfonylalanine (NPNPSA) and N-paranitrophenylalanine (NPNPA), the photoelectron spectrum of the valence anion of N-paranitrophenylsulfonylalanine (NPNPSA)(-), was measured and the collision-induced dissociation (CID) pathways of deprotonated N-paranitrophenylsulfonylalanine (NPNPSA-H)(-) and deprotonated N-paranitrophenylalanine (NPNPA-H)(-) were determined. Pertinent calculations were conducted to analyze both sets of experimental data. From the valence anion photoelectron spectrum of (NPNPSA)(-), the adiabatic electron affinity (AEA) of NPNPSA was determined to be 1.7 ± 0.1 eV, while the vertical detachment energy (VDE) of (NPNPSA)(-) was found to be 2.3 ± 0.1 eV. Calculations for four low lying conformers of (NPNPSA)(-) gave AEA values in the range of 1.6-2.1 eV and VDE values in the range of 2.0-2.4 eV. These calculations are in very good agreement with the experimental values. While the NPNPA anion (NPNPSA)(-) was not observed experimentally it was studied computationally. The six low lying (NPNPSA)(-) conformers were identified and calculated to have AEA values in the range of 0.7-1.2 eV and VDE values in the range of 0.9-1.6 eV. CID was used to study the fragmentation patterns of deprotonated NPNPA and deprotonated NPNPSA. Based on the CID data and calculations, the excess charge was located on the delocalized π-orbitals of the nitrobenzene moiety. This is made evident by the fact that the dominant fragments all contained the nitrobenzene moiety even though the parent anions used for the CID study were formed via deprotonation of the carboxylic acid. The dipole-bound anions of both molecules are studied theoretically using the results of previous studies on nitrobenzene as a reference.
authors: Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors: Jason
authors: J
authors: Lambert
authors: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors: Jing
authors: J
authors: Chen
authors: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors: Angela
authors: A
authors: Buonaugurio
authors: Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors: Kit H
authors: KH
authors: Bowen
authors: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors: Chi-Linh
authors: CL
authors: Do-Thanh
authors: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors: Yilin
authors: Y
authors: Wang
authors: Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors: Michael D
authors: MD
authors: Best
authors: Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.
authors: R N
authors: RN
authors: Compton
authors: Department of Chemistry and Physics, Southeastern Louisiana University, Hammond, Louisiana 70402, USA.
authors: Thomas
authors: T
authors: Sommerfeld
mesh_terms: D003622:Dapsone / Q000031:analogs & derivatives* / Q000737:chemistry*; D004583:Electrons; D008027:Light; D008958:Models, Molecular; D008968:Molecular Conformation; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C040239:4-nitrophenylalanine; D010649:Phenylalanine; D003622:Dapsone