Mechanistic Insight into <i>Cypridina</i> Bioluminescence with a Combined Experimental and Theoretical Chemiluminescent Approach

Silva, Luís Pinto da; Pereira, Rui; Magalhães, Carla M.; Silva, Joaquim C. G. Esteves da

doi:10.1021/acs.jpcb.7b06295

Cited by 27 publications

(121 citation statements)

References 83 publications

(361 reference statements)

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“…However, even CTIL have failed to explain some experimental and theoretical results. Theoretical calculations have shown that neutral imidazopyrazinone‐based dioxetanones present more efficient S 0 →S 1 chemiexcitation pathways than anionic dioxetanones . This results from the fact that neutral peroxides have access to a large and flat potential energy surface (PES) region of degeneracy between S 0 and S 1 states found within the biradical region.…”

Section: Introductionmentioning

confidence: 66%

“…These results once again put into question the validity of both CIEEL and CTIL mechanisms, as efficient chemiexcitation was ascribed to a neutral molecule instead of an ionized one. More relevant evidence regarding this topic was given by the analysis of the electron/charge density of neutral/anionic Cypridina dioxetanone, as a function of the thermolysis reaction . We found that despite both molecules undergoing different chemiexcitation pathways, both dioxetanone species decompose with significant ET/BET and CT/BCT between the imidazopyrazinone and dioxetanone moieties .…”

Section: Introductionmentioning

confidence: 81%

“…Ionic dioxetanones have been found to not have access to this region of degeneracy. Moreover, the S 0 →S 1 energy gap within the biradical region for ionic peroxides is significantly higher than for neutral dioxetanones, which indicates a lower efficiency of chemiexcitation . These conclusions have been supported by experimental studies on imidazopyrazinones and other systems .…”

Section: Introductionmentioning

confidence: 84%

“…Moreover, the S 0 →S 1 energy gap within the biradical region for ionic peroxides is significantly higher than for neutral dioxetanones, which indicates a lower efficiency of chemiexcitation . These conclusions have been supported by experimental studies on imidazopyrazinones and other systems . Indirect experimental data obtained from both Cypridina and the firefly systems also indicate that efficient chemiexcitation is caused by the thermolysis of neutral dioxetanones .…”

Section: Introductionmentioning

confidence: 84%

“…By determining energy and kinetic chemiluminescent profiles, we have found that chemiluminescence has a higher reaction rate at higher pH, whereas it presents stronger light emission with decreasing pH. Despite this, these differences cannot be explained by considering different emitters . Subsequent density functional theory (DFT) and time‐dependent (TD)‐DFT calculations allowed us to explain these findings by taking into account the ionization state of the dioxetanone intermediate .…”

Section: Introductionmentioning

confidence: 92%

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Mechanistic insights into the efficient intramolecular chemiexcitation of dioxetanones from TD‐DFT and multireference calculations

Silva

Magalhães

2018

Int J of Quantum Chemistry

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Despite decades of research, it is still not clear what is the mechanism behind the efficient chemiexcitation of dioxetanones in chemiluminescent and bioluminescent reactions. In fact, long‐standing theories (charge transfer‐initiated luminescence and chemically induced electron‐exchange luminescence) have been demonstrated to not be able to explain this phenomenon. Herein, a theoretical approach using reliable and up‐to‐date methodology was used to address this problem, by focusing on model dioxetanones. Time‐dependent (TD)‐Density functional theory (DFT) and multireference complete‐active‐space second‐order perturbation theory (CASPT2) calculations provided evidence that points to efficient intramolecular chemiexcitation being the result of the reacting molecules having access to a long zone of the Potential energy surface (PES), within the biradicalar region, where S0 and S1 are degenerate. Molecules with inefficient chemiexcitation are unable to reach this zone of degeneracy. Our main finding is that access to the region of degeneracy appears to be given due to increased interaction between the keto and CO2 moieties, as supported by the use of the activation strain model and Born‐Oppenheimer molecular dynamics, which extends the biradical region by delaying the rupture of the peroxide ring. Increased interaction derives from attractive electrostatic interactions between the moieties of dioxetanone. Thus, we hypothesize that efficient chemiexcitation results not only from electron/charge transfer and subsequent charge annihilation but is instead based on the degree of interaction between the keto and CO2 moieties, which controls the access to a region of degeneracy between the ground and excited states.

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Section: Introductionmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 92%

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Mechanistic insights into the efficient intramolecular chemiexcitation of dioxetanones from TD‐DFT and multireference calculations

Silva

Magalhães

2018

Int J of Quantum Chemistry

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Molecular Basis of the Chemiluminescence Mechanism of Luminol

Giussani

Farahani

Martínez‐Muñoz

et al. 2019

Chemistry A European J

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Light emission from luminol is probably one of the most popular chemiluminescence reactions due to its use in forensic science, and has recently displayed promising applications for the treatment of cancer in deep tissues. The mechanism is, however, very complex and distinct possibilities have been proposed. By efficiently combining DFT and CASPT2 methodologies, the chemiluminescence mechanism has been studied in three steps: 1) luminol oxygenation to generate the chemiluminophore, 2) a chemiexcitation step, and 3) generation of the light emitter. The findings demonstrate that the luminol double‐deprotonated dianion activates molecular oxygen, diazaquinone is not formed, and the chemiluminophore is formed through the concerted addition of oxygen and concerted elimination of nitrogen. The peroxide bond, in comparison to other isoelectronic chemical functionalities (−NH−NH−, −N−−N−−, and −S−S−), is found to have the best chemiexcitation efficiency, which allows the oxygenation requirement to be rationalized and establishes general design principles for the chemiluminescence efficiency. Electron transfer from the aniline ring to the OO bond promotes the excitation process to create an excited state that is not the chemiluminescent species. To produce the light emitter, proton transfer between the amino and carbonyl groups must occur; this requires highly localized vibrational energy during chemiexcitation.

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The Fluorescent Properties of pH‐Independent Cypridina Oxyluciferin Derivatives

et al. 2019

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The co‐factors independent cypridina bioluminescence was often used to detect molecular oxygen. Whereas the native cypridina oxyluciferin and the majority analogues only emit blue light, it limits the application of the cypridina oxyluciferin derivative in detection active oxygen species. To overcome these limitations, we design two series of oxyluciferin derivatives: 2‐acetamido‐5‐aryl‐3‐(p‐trifluoromethylphenyl)pyrazine and 2‐acetamido‐5‐aryl‐3‐(p‐methoxylphenyl)pyrazine. The results found that the fluorescence emissions of the cypridina oxyluciferin derivatives cover the whole region of visible light. Especially, 2‐acetamido‐5‐(trans‐2,3,6,7‐tetrahydro‐1H,5H‐benzo[i,j]quinolizine‐ethenyl)‐3‐(p‐trifluoromethyl phenyl)pyrazine (1 h) can emit red light. By comparison of the emission spectra and oscillator strengths, it found that electron‐donating group in C3 position contributed to blue shift wavelength and improve luminous efficiency. The increasing conjugated length by introducing a conjugated double bond made the emission spectra shift to red and the luminescence strengths much stronger. Moreover, the analysis of the relative stabilities at the ground and excited states indicates that neutral forms, not amide ions, are dominant at physiological pH.

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Mechanistic Insight into Cypridina Bioluminescence with a Combined Experimental and Theoretical Chemiluminescent Approach

Cited by 27 publications

References 83 publications

Mechanistic insights into the efficient intramolecular chemiexcitation of dioxetanones from TD‐DFT and multireference calculations

Mechanistic insights into the efficient intramolecular chemiexcitation of dioxetanones from TD‐DFT and multireference calculations

Molecular Basis of the Chemiluminescence Mechanism of Luminol

The Fluorescent Properties of pH‐Independent Cypridina Oxyluciferin Derivatives

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