Determinação das constantes de dissociação protônica do 2,7-naftalenodiol no primeiro estado excitado singlete por experimentos com resolução temporal e modelagem matemática - DOI: 10.4025/actascitechnol.v28i1.1200

Ira Mark Brinn; Mauricio Ferreira Rosa

doi:10.4025/actascitechnol.v28i1.1200

Determination of protonic dissociation constants of 2.7-naphthalenediol in the first excited singlet state by experiments with temporal resolution and mathematical modeling - DOI: 10.4025/actascitechnol.v28i1.1200

Authors

Ira Mark Brinn UFRJ
Mauricio Ferreira Rosa UNIOESTE

DOI:

https://doi.org/10.4025/actascitechnol.v28i1.1200

Keywords:

2, 7-naphthanediol, pKa measurements, kinetic modeling, fluorescence decay

Abstract

By using the steady-state spectroscopy technique, it was possible to determine the acidity constants of 2.7-naphthalenediol (27ND) in the ground (pK_a) and excited states (pK_a*). The results of pK_a and pK_a* obtained, were respectively 9.54 and 6.5. This last value is in poor agreement with the values previously reported. Allying time-correlated single photon counting (TCSPC) experiments and kinetic model calculations made possible to determine, for the first time, the rate constants for the protonic dissociation of 27ND, in the first excited singlet state. The rate constants obtained are: k₁ = 1.1x10⁸s^-1; k₂ = 2.9x10⁸ s^-1; k₃ = 7.4x10⁸ s^-1; k_d1 = 8.0x10⁷ M^-1s^-1; k_r1 = 5.0x10¹⁰ M^-1s^-1 and kd2 = 1.0x10⁷ M^-1s^-1. The acidity constant in the first excited singlet state (pK_a*) calculated by the kinetic method (ratio of k_d1 and k_r1) was 2.8. This value is in best agreement with the ones previously reported in the literature obtained by graphic methods

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Author Biography

Mauricio Ferreira Rosa, UNIOESTE

Possui graduação em Química (Bacharelado) pela Universidade Federal do Rio de Janeiro (1989) e graduação em Licenciatura Plena em Química pela Universidade do Estado do Rio de Janeiro (1996). Mestre em Química Orgânica pela Universidade Federal do Rio de Janeiro (1993) e Doutor em Química Orgânica pela Universidade Federal do Rio de Janeiro (1999), ambos sob a orientação do Prof. Dr. Ira Mark Brinn. Já lecionou no ensino médio no Rio de Janeiro e atualmente é professor adjunto C da Universidade Estadual do Oeste do Paraná, na área de Química Orgânica e Bioquímica e coordenador do curso. Tem experiência na área de Química, com ênfase em Fotoquímica e Físico-Química Orgânica, atuando principalmente nos seguintes temas: síntese de heterociclos, espectroscopia, fotoquímica e ensino de química. É consultor das revistas Acta Scientiarum, Technology (UEM) Varia Scientia (UNIOESTE). Membro do banco de avaliadores de cursos e instituição pelo SINAES Currículo Lattes

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Published

2008-03-20

How to Cite

Brinn, I. M., & Rosa, M. F. (2008). Determination of protonic dissociation constants of 2.7-naphthalenediol in the first excited singlet state by experiments with temporal resolution and mathematical modeling - DOI: 10.4025/actascitechnol.v28i1.1200. Acta Scientiarum. Technology, 28(1), 5–12. https://doi.org/10.4025/actascitechnol.v28i1.1200

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Issue

Vol. 28 No. 1 (2006)

Section

Chemistry

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0.8

2019CiteScore

36th percentile