title: Zinc- and copper-porphyrins in aqueous solution - two similar complexes with strongly contrasting hydration.
abstract: We present detailed analysis of the hydration behavior of zinc and copper bound porphyrins treated via ab initio quantum mechanical charge field molecular dynamics which agrees well with available experimental data. The computed metal-water coordination in the case of zinc bound porphyrin demonstrates a strong association of water with zinc compared to the copper-water interaction which correlates well with the calculated free energy of binding. The H-bond dynamics in these hydrated systems yield weaker H-bond interactions as compared to that observed in the case of metal-free porphyrin; nevertheless, the effect of metal association with porphyrin resulted in shifts in the vibrational frequencies. These characteristic data suggest a contrasting behavior between these metalloporphyrins in solution which could also serve to correlate with the properties of biological systems.
authors.affiliation: H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi-75270, Pakistan. tarique.syed@iccs.edu.
authors.forename: Syed Tarique
authors.initials: ST
authors.lastname: Moin
authors.affiliation: Theoretical Chemistry Division, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria. T.Hofer@uibk.ac.at.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hofer
mesh_terms: D003300:Copper / Q000737:chemistry*; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008665:Metalloporphyrins / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D012996:Solutions; D014867:Water / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D008665:Metalloporphyrins; D011166:Porphyrins; D012996:Solutions; D014867:Water; D003300:Copper; D015032:Zinc