The Methylene Blue Self-aggregation in Water/Organic Solvent Mixtures: Relationship Between Solvatochromic Properties and Singlet Oxygen Production

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Moreira, Leonardo Marmo ^[1] ; Lyon, Juliana Pereira ^[1] ; Lima, Adriana ^[2] ; Codognoto, Lucia ^[3] ; Severino, Divinomar ^[4] ; Baptista, Mauricio S. ^[4] ; Tessaro, Andre Luiz ^[5] ; Gerola, Adriana Passarela ^[6] ; Hioka, Noboru ^[7] ; Rodrigues, Maira Regina ^[8] ; Bonacin, Juliano Alves ^[9] ; dos Santos, Sandra Cruz ^[10] ; Romani, Ana Paula ^[11] ; Moises de Oliveira, Hueder Paulo ^[12]

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^[1] Univ Fed Sao Joao del Rei, Dept Zootecnia DEZOO, Campus Dom Bosco, BR-36301160 Sao Joao Del Rei, MG - Brazil

^[2] Univ Vale Paraiba, Ave Shishima Hifumi 2911, BR-12244000 Sao Paulo - Brazil

^[3] Univ Fed Sao Paulo, Dept Quim, Rua Prof Arthur Riedel 275, BR-09972270 Sao Paulo - Brazil

^[4] Univ Sao Paulo, Dept Bioquim, Inst Quim, Ave Prof Lineu Prestes 748, BR-05508900 Sao Paulo, SP - Brazil

^[5] Univ Tecnol Fed Parana, Campus Apucarana, Rua Marcilio Dias 635, BR-86812460 Apucarana, Parana - Brazil

^[6] Univ Fed Santa Catarina, BR-88040900 Florianopolis, SC - Brazil

^[7] Univ Estadual Maringa, Dept Quim, Av Colombo 5790, Zona 07, BR-87020900 Maringa, Parana - Brazil

^[8] Univ Fed Rio de Janeiro, Campus Macae, Rua Aloisio da Silva Gomes 50, BR-27930560 Rio De Janeiro - Brazil

^[9] Univ Estadual Campinas, Inst Quim, BR-13083970 Sao Paulo - Brazil

^[10] Univ Fed Rio Grande, Escola Quim & Alimentos, Campus Carreiros Pavilhao Quim, BR-96201900 Rio Grande, RS - Brazil

^[11] Univ Fed ABC, Ctr Engn Modelagem & Ciencias Sociais Aplicadas, Ave Estados 5001, BR-09210580 Sao Paulo - Brazil

^[12] Univ Fed ABC, Ctr Ciencias Nat & Humanas, Ave Estados 5001, BR-09210580 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: ORBITAL-THE ELECTRONIC JOURNAL OF CHEMISTRY; v. 9, n. 4, p. 279-289, JUL-SEP 2017.
• Citações Web of Science: 1

Resumo

In this work is presented a spectrophotometric investigation focused on the solvatochromic effects upon Methylene Blue (MB). Measurements were carried out in four different water/organic solvent mixtures: low polarity protic solvent (ethanol), polar non-protic solvent (acetonitrile), highly polar protic solvent (glycerol), and non-polar solvent (dioxane). The results showed that the photophysical behavior of MB is highly affected by self-aggregates formation at 80% of water/organic solvent blends. Besides polarity, the protic character and the coordinating properties of the solvent molecules are the key parameters for its photophysical behavior, since the sulfur atom of the cationic structure can act as a coordination center due to its Lewis acid character. In fact, water and acetonitrile coordinating properties have proved to be important to determine MB interactions intensity and its spectroscopic properties as singlet oxygen emission. It was observed that an increase of the amount of the organic solvent resulted in an enhancement of the singlet oxygen emission intensity. The presence of the water increases the dielectric constant of the medium and favors the self-aggregation process. Besides, the water molecules can act as a quencher and it decreases the quantum yield of the fluorescence of MB. (AU)

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