Theoretical Studies of Excited State 1,3 Dipolar Cycloadditions

Created by W.Langdon from gp-bibliography.bib Revision:1.4504

  author =       "Michael Anthony Bellucci",
  title =        "Theoretical Studies of Excited State 1,3 Dipolar
  school =       "Boston University",
  year =         "2012",
  address =      "USA",
  keywords =     "genetic algorithms, genetic programming, Chemistry,
                 Dipolar cycloaddition, Excited state, Hydroxy flavone,
                 Methyl cinnamate, Physical chemistry, Proton transfer,
                 Pure science, Quantum physics",
  URL =          "",
  URL =          "",
  abstract =     "The 1,3 dipolar photocycloaddition reaction between
                 3-hydroxy-4',5,7-trimethoxyflavone (3-HTMF) and methyl
                 cinnamate is investigated in this work. Since its
                 inception in 2004 [JACS, 124, 13260 (2004)], this
                 reaction remains at the forefront in the synthetic
                 design of the rocaglamide natural products. The
                 reaction is multi-faceted in that it involves multiple
                 excited states and is contingent upon excited state
                 intramolecular proton transfer (ESIPT) in 3-HTMF. Given
                 the complexity of the reaction, there remain many
                 questions regarding the underlying mechanism.
                 Consequently, throughout this work we investigate the
                 mechanism of the reaction along with a number of other
                 properties that directly influence it. To investigate
                 the photocycloaddition reaction, we began by studying
                 the effects of different solvent environments on the
                 ESIPT reaction in 3-hydroxyflavone since this
                 underlying reaction is sensitive to the solvent
                 environment and directly influences the cycloaddition.
                 To study the ESIPT reaction, we developed a parallel
                 multi-level genetic program to fit accurate empirical
                 valence bond (EVB) potentials to ab initio data. We
                 found that simulations with our EVB potentials
                 accurately reproduced experimentally determined
                 reaction rates, fluorescence spectra, and vibrational
                 frequency spectra in all solvents. Furthermore, we
                 found that the ultrafast ESIPT process results from a
                 combination of ballistic transfer and intramolecular
                 vibrational redistribution. To investigate the
                 cycloaddition reaction mechanism, we used the string
                 method to obtain minimum energy paths on the ab initio
                 potential. These calculations demonstrated that the
                 reaction can proceed through formation of an exciplex
                 in the S1 state, followed by a non-adiabatic transition
                 to the ground state. In addition, we investigated the
                 enantioselective catalysis of the reaction using
                 alcohol (TADDOL). We found that TADDOL lowered the
                 energy barrier by 10-12 kcal/mol through stabilizing
                 hydrogen bond interactions. Using temperature
                 accelerated molecular dynamics, we obtained the
                 potential of mean force (PMF) associated with 3-HTMF
                 attacking the TADDOL/methyl cinnamate complex. We found
                 that the exo reaction is inhibited through steric
                 interactions with the aryl substituents on TADDOL.
                 Furthermore, we found that the exo configuration breaks
                 the intramolecular hydrogen bond in TADDOL, which
                 stabilizes the individual reactants apart from each
                 other. The role of the T1 state is also discussed.",
  notes =        "",

Genetic Programming entries for Michael A Bellucci