Centro de Investigação em Química (CIQUP), Instituto de Ciências Moleculares (IMS), Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
LACOMEPHI, GreenUPorto, Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal.
Molecules. 2022 Jun 16;27(12):3861. doi: 10.3390/molecules27123861.
The intramolecular chemiexcitation of high-energy peroxide intermediates, such as dioxetanones, is an essential step in different chemi- and bioluminescent reactions. Here, we employed the Time-Dependent Density Functional Theory (TD-DFT) methodology to evaluate if and how external stimuli tune the intramolecular chemiexcitation of model dioxetanones. More specifically, we evaluated whether the strategic placement of ionic species near a neutral dioxetanone model could tune its thermolysis and chemiexcitation profile. We found that these ionic species allow for the "dark" catalysis of the thermolysis reaction by reducing the activation barrier to values low enough to be compatible with efficient chemi- and bioluminescent reactions. Furthermore, while the inclusion of these species negatively affected the chemiexcitation profile compared with neutral dioxetanones, these profiles appear to be at least as efficient as anionic dioxetanones. Thus, our results demonstrated that the intramolecular chemiexcitation of neutral dioxetanones can be tuned by external stimuli in such a way that their activation barriers are decreased. Thus, these results could help to reconcile findings that neutral dioxetanones could be responsible for efficient chemi-/bioluminescence, while being typically associated with high activation parameters.
高能过氧化物中间体(如二氧杂环戊酮)的分子内化学激发是许多化学发光和生物发光反应的关键步骤。在这里,我们采用含时密度泛函理论(TD-DFT)方法来评估外部刺激是否以及如何调节模型二氧杂环戊酮的分子内化学激发。更具体地说,我们评估了在中性二氧杂环戊酮模型附近放置离子物种是否可以调节其热解和化学激发特性。我们发现,这些离子物种可以通过降低热解反应的活化能垒,使其值足够低,从而与有效的化学发光和生物发光反应兼容,从而实现“暗”催化。此外,尽管与中性二氧杂环戊酮相比,这些物种的存在会对化学激发特性产生负面影响,但这些特性似乎至少与阴离子二氧杂环戊酮一样有效。因此,我们的结果表明,外部刺激可以调节中性二氧杂环戊酮的分子内化学激发,从而降低其活化能垒。因此,这些结果可能有助于解释为什么中性二氧杂环戊酮能够产生高效的化学/生物发光,而通常与高活化参数相关联。