Intramolecular interactions of L-phenylalanine: valence ionization spectra and orbital momentum distributions of its fragment molecules

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Title: Intramolecular interactions of L-phenylalanine: valence ionization spectra and orbital momentum distributions of its fragment molecules
Author(s): Ganesan, Aravindhan; Wang, Feng; Falzon, Chantal
Abstract: Intramolecular interactions between fragments of L-phenylalanine, i.e., phenyl and alaninyl, have been investigated using dual space analysis (DSA) quantum mechanically. Valence space photoelectron spectra (PES), orbital energy topology and correlation diagram, as well as orbital momentum distributions (MDs) of L-phenylalanine, benzene and L-alanine are studied using density functional theory methods. While fully resolved experimental PES of L-phenylalanine is not yet available, our simulated PES reproduces major features of the experimental measurement. For benzene, the simulated orbital MDs for 1e1g and 1a2u orbitals also agree well with those measured using electron momentum spectra. Our theoretical models are then applied to reveal intramolecular interactions of the species on an orbital base, using DSA. Valence orbitals of L-phenylalanine can be essentially deduced into contributions from its fragments such as phenyl and alaninyl as well as their interactions. The fragment orbitals inherit properties of their parent species in energy and shape (ie., MDs). Phenylalanine orbitals show strong bonding in the energy range of 14-20 eV, rather than outside of this region. This study presents a competent orbital based fragments-inmolecules picture in the valence space, which supports the fragment molecular orbital picture and building block principle in valence space. The optimized structures of the molecules are represented using the recently developed interactive 3D-PDF technique.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Molecular Simulation
Source: Journal of Computational Chemistry, Vol. 32, no. 3 (Feb 2011), pp. 525-535
Publication year: 2011
FOR Code(s): 0306 Physical Chemistry (Incl. Structural); 0307 Theoretical and Computational Chemistry
Keyword(s): Intramolecular interactions; L-phenylalanine; Molecular interactions
Publisher: John Wiley & Sons
ISSN: 0192-8651
Publisher URL: http://dx.doi.org/10.1002/jcc.21639
Peer reviewed