The valence and core electronic structure of three non-steroidal anti-inflammatory drugs (methyl salicylate, fenoprofen and ketoprofen) have been studied by photoelectron and soft X-ray absorption spectroscopy, supported by theoretical calculations of the molecular and electronic structure. The conformational landscape has been explored for sixteen low-energy conformers of fenoprofen and ketoprofen, and the energies of both compounds fall into two groups with steric similarities, separated by about 3 kJ mol-1. Valence band photoelectron spectra agree with previous results, and the spectra have been calculated using two approaches. We find the outer valence Green's function method gives good results, but the P3+ method is a little better, particularly for outer valence ionic states. Carbon and oxygen 1s photoemission spectra are reported and are in acceptable agreement with the theory. The C and O K near-edge X-ray absorption fine structure spectra are reported and interpreted by comparison with reference compounds. We analyse the data to provide rough estimates of the energies of the unoccupied orbitals in methyl salicylate.

Charles University Faculty of Mathematics and Physics Department of Surface and Plasma Science 5 Holešovičkách 2 Prague 18000 Czech Republic

CNR Istituto di Struttura della Materia Area Science Park Basovizza S S 14 Km 163 5 Trieste 34149 Italy

CNR Istituto Officina dei Materiali Area Science Park Basovizza S S 14 Km 163 5 Trieste 34149 Italy

Department of Physics The University of Jordan Amman 11942 Jordan

Dipartimento di Chimica G Ciamician Università di Bologna 40139 Bologna Italy

Elettra Sincrotrone Trieste in Area Science Park 34149 Basovizza Trieste Italy

References provided by Crossref.org