Pinto da Silva L, Magalhães C M, Crista D M A, Esteves da Silva J C G
Chemistry Research Unit (CIQUP), Department of Chemistry and Biochemistry, Faculty of Sciences of University of Porto, R. Campo Alegre 687, 4169-007 Porto, Portugal.
Photochem Photobiol Sci. 2017 Jun 14;16(6):897-907. doi: 10.1039/c7pp00012j.
Coelenterazine, a member of the imidazopyrazinone class of chemiluminescent substrates, presents significant potential as a dynamic probe of reactive oxygen species in a biological environment, such as a superoxide anion, in which these species are important in cellular biology and pathology. The objective of the current study was to understand in what way the efficiency of singlet and triplet chemiexcitation could be modulated, towards a more efficient use of imidazopyrazinone-based compounds as dynamic chemiluminescent probes. To this end the thermolysis of imidazopyrazinone dioxetanone, substituted at the C-position with electron-donating or electron-withdrawing groups, was characterized with a theoretical approach based on density functional theory. Substituents with different electron-donating/withdrawing characters have only a limited effect on the singlet chemiexcitation of anionic dioxetanone. For neutral dioxetanone, both electron-withdrawing and weak electron-donating substituents increase singlet chemiexcitation, to the contrary of strong electron-donating groups. During their thermolysis reaction, all molecules presented regions of degeneracy with triplet states, thereby indicating the possibility of triplet chemiexcitation.
腔肠素是咪唑并吡嗪酮类化学发光底物的一种，作为生物环境中活性氧物种（如超氧阴离子）的动态探针具有巨大潜力，在细胞生物学和病理学中这些物种起着重要作用。本研究的目的是了解如何调节单线态和三线态化学激发的效率，以便更有效地将基于咪唑并吡嗪酮的化合物用作动态化学发光探针。为此，采用基于密度泛函理论的理论方法对在C位被供电子或吸电子基团取代的咪唑并吡嗪酮二氧杂环丁烷的热解进行了表征。具有不同供电子/吸电子特性的取代基对阴离子二氧杂环丁烷的单线态化学激发影响有限。对于中性二氧杂环丁烷，吸电子和弱供电子取代基都会增加单线态化学激发，而强供电子基团则相反。在热解反应过程中，所有分子都呈现出与三线态的简并区域，从而表明存在三线态化学激发的可能性。
