title: Structural Substituent Effect in the Excitation Energy of a Chromophore: Quantitative Determination and Application to S-Nitrosothiols.
abstract: A methodology for the prediction of excitation energies for substituted chromophores on the basis of ground state structures has been developed. The formalism introduces the concept of "structural substituent excitation energy effect" for the rational prediction and quantification of the substituent effect in the excitation energy of a chromophore to an excited electronic state. This effect quantifies exclusively the excitation energy variation due to the structural changes of the chromophore induced by the substituent. Therefore, excitation bathochromic and hypsochromic shifts of substituted chromophores can be predicted on the basis of known ground and excited potential energy surfaces of a reference unsubstituted chromophore, together with the ground state minimum energy structure of the substituted chromophore. This formalism can be applied if the chemical substitution does not affect the nature of the electronic excitation, where the substituent effect can be understood as a force acting on the chromophore and provoking a structural change on it. The developed formalism provides a useful tool for quantitative and qualitative determination of the excitation energy of substituted chromophores and also for the analysis and determination of the structural changes affecting this energy. The proposed methodology has been applied to the prediction of the excitation energy to the first bright state of several S-nitrosothiols using the potential energy surfaces of methyl-S-nitrosothiol as a reference unsubstituted chromophore.
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Fernández-González
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Marco
authors.initials: M
authors.lastname: Marazzi
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: López-Delgado
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Zapata
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: García-Iriepa
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Rivero
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Obis
authors.initials: O
authors.lastname: Castaño
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Temprado
authors.affiliation: Departamento de Química Física, Universidad de Alcalá, E-28871 Alcalá de Henares (Madrid), Spain.
authors.forename: Luis Manuel
authors.initials: LM
authors.lastname: Frutos