(Invited) Low Frequency Modes of Porphyrin Systems

Abstract

Nuclear resonance scattering is an ideal tool to study electronic and dynamic properties of iron centers in chemical and biological systems. During the last years Nuclear Resonance Vibrational Spectroscopy (NRVS) also called Nuclear Inelastic Scattering (NIS) has been used to detect iron based vibrational modes heme proteins and model complexes. We have investigated the vibrational modes of the heme model complex [TPPFeIII(NH2Pz)2]Cl [1], both experimentally via NRVS and theoretically by density functional theory (DFT) calculations in the region from ~5 to ~800 cm-1. DFT calculations coupled with molecular mechanics allow to investigate solvent effects. First preliminary calculations show, that the vibrational modes of [TPPFeIII(NH2Pz)2]Cl are not significantly influenced by the solvent. In addition the effect of solvent on the low frequency modes of the NO transporter protein nitrophorin [2,3] will be presented. This work has been supported by the research initiative NANOKAT and by the German Federal Ministry of Education and Research. [1] V. Schünemann, A.M. Raitsimring, R. Benda, A.X. Trautwein, T.K. Shokireva, F.A. Walker, JBIC 4 (1999) 708-716. [2] B. Moeser, A. Janoschka, J.A. Wolny, H. Paulsen, I. Fillipov, R.E. Berry, H. Zhang, A.I. Chumakov, F.A. Walker, V. Schünemann, J. Am. Chem. Soc. 134(9) (2012) 4216-4228. [3] H. Auerbach, I. Faus, S. Rackwitz, J.A. Wolny, F.A. Walker, A.I. Chumakov, H. Ogata, M. Knipp, V. Schünemann, Hyperfine Interact. 226 (2014) 439-443.