title: Protonated serotonin: Geometry, electronic structures and photophysical properties.
abstract: The geometry and electronic structures of protonated serotonin have been investigated by the aim of MP2 and CC2 methods. The relative stabilities, transition energies and geometry of sixteen different protonated isomers of serotonin have been presented. It has been predicted that protonation does not exhibit essential alteration on the S1←S0electronic transition energy of serotonin. Instead, more complicated photophysical nature in respect to its neutral analogue is suggested for protonated system owing to radiative and non-radiative deactivation pathways. In addition to hydrogen detachment (HD), hydrogen/proton transfer (H/PT) processes from ammonium to indole ring along the NH+⋯π hydrogen bond have been predicted as the most important photophysical consequences of SERH+at S1excited state. The PT processes is suggested to be responsible for fluorescence of SERH+while the HD driving coordinate is proposed for elucidation of its nonradiative deactivation mechanism.
authors.affiliation: Department of Chemistry, University of Isfahan, 81746-73441, Isfahan, Iran. Electronic address: r.omidyan@sci.ui.ac.ir.
authors.forename: Reza
authors.initials: R
authors.lastname: Omidyan
authors.affiliation: Department of Chemistry, University of Isfahan, 81746-73441, Isfahan, Iran.
authors.forename: Zohreh
authors.initials: Z
authors.lastname: Amanollahi
authors.affiliation: Department of Chemistry, University of Isfahan, 81746-73441, Isfahan, Iran.
authors.forename: Gholamhassan
authors.initials: G
authors.lastname: Azimi
mesh_terms: D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D007536:Isomerism; D008958:Models, Molecular; D011522:Protons; D012701:Serotonin / Q000737:chemistry*
chemical_list: D011522:Protons; D012701:Serotonin; D006859:Hydrogen
keywords: CC2; Excited states; MP2 methods; Photophysics; Protonated