Regiochemical memory in the adiabatic photolysis of thymine-derived oxetanes. A combined ultrafast spectroscopic and CASSCF/CASPT2 computational study

Blasco-Brusola, Alejandro; Navarrete‐Miguel, Miriam; Giussani, Angelo; Roca‐Sanjuán, Daniel; Vayá, Ignacio; Miranda, Miguel A.

doi:10.1039/d0cp03084h

Cited by 8 publications

(24 citation statements)

References 42 publications

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“…The ways in which carbonyl compounds behave after the absorption of photons is well documented. 1 Commonly used as starting materials for a wide range of reactions, carbonyl-containing organic molecules got increasing attention for their efficiency as photosensitisers and photocatalysts. [2][3] Their absorption power lies on their double-bond, formed by the fusion of the two half-full 2p orbitals of the C and the O (see Figure 1.4, with formaldehyde as an example), and also on one of the sp 2 hybridized orbitals of both atoms.…”

Section: Photochemistry Of Carbonyl Compoundsmentioning

confidence: 99%

“…The molar absorption coefficient for n  π* is relatively low (40 M -1 cm -1 ), which is why it is usually obscured by the stronger π  π* absorption. 1 The easily-accessible triplet excited state helps to explain the high photoreactivity of carbonyl compounds. If R 1 and/or R 2 (Figure 1.5) are aromatic, depending on their substituents, they could affect the energy levels of the triplets, and consequently the one of lower energy.…”

Section: Photochemistry Of Carbonyl Compoundsmentioning

confidence: 99%

“…The interaction of solar UV light with DNA can give rise to chemical modifications in its structure that may result in cell death and eventually in the appearance of cancer. [1][2] Direct photoinduced damage is mainly associated with the formation of cyclobutane pyrimidine dimers (CPDs)…”

Section: Introductionmentioning

confidence: 99%

“…Solar ultraviolet light is known to induce cellular DNA damage through a number of processes including the dimerization of neighbouring pyrimidines. [1][2][3][4] Cyclobutane pyrimidine dimers (CPDs) and to a lesser extent pyrimidine (6-4) pyrimidone photoproducts ((6-4)PPs) are the most abundant UV-induced lesions in DNA; [4][5][6] their formation may result in the appearance of mutations, cell death and cancer. [7][8][9] In humans, these lesions are normally repaired through a process known as nucleotide excision repair; however, other organisms (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…The origin of human diseases such as skin cancer can be associated in many cases to photoinduced DNA damage. [1][2][3] Thus, when DNA absorbs UV light, a cascade of reactions may lead to the formation of cyclobutane pyrimidine dimers (CPDs) and to a lesser extent pyrimidine-pyrimidone (6-4) photoproducts ((6-4)PPs), which may result in the appearance of mutations and cell death. [4][5][6][7] The CPD photolesions can also arise from photosensitization, where an endogenous or exogenous photosensitizer (PS) can absorb UVA light to generate long-lived reactive species such as excited triplet states that will be the initiators of the damaging reactions.…”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Studies on the Photochemical Formation and Cleavage of Oxetanes Derived from Pyrimidine Bases

Brusola¹

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Most of my predecessors like to describe their time as a PhD student as an "adventure", I prefer to refer it as a rollercoaster: In the beginning you are overwhelmed with a strong urge to scream in terror and you just wish it to be over as soon as possible…until the adrenaline starts to kick in, and you begin to actually enjoy the ride. Suddenly the twists and turns become more predictable, giving you a sensation of being in greater control of the situation, hence boosting self-confidence, and even making you look forward for the next loop. You feel alive. And like most rollercoasters, you rarely ride it alone. This thesis, that so much hard work has taken, is dedicated to all the people who were, in one way or another, next to me, and who have helped me make this 3-year ride more bearable.First and foremost are my parents, who were able to guide me both personally and professionally to become the best doctor I could aspire to be.Professionally I will always be grateful to both of my directors: Prof. Miguel Angel Miranda Alonso and Dr. Ignacio Váya Pérez. They were one of the few who, since the very beginning, had treated me like an adult, a professional in the making, as opposed to a teenager that needed to be disciplined. Thank you for your guidance, respect and encouragement, and your constructive criticism. I would never have gotten this far without you.

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Section: Photochemistry Of Carbonyl Compoundsmentioning

confidence: 99%

Section: Photochemistry Of Carbonyl Compoundsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mechanistic Studies on the Photochemical Formation and Cleavage of Oxetanes Derived from Pyrimidine Bases

Brusola¹

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Influence of the Linking Bridge on the Photoreactivity of Benzophenone–Thymine Conjugates

2020

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Benzophenone (BP) is present in a variety of bioactive molecules. This chromophore is able to photosensitize DNA damage, where one of the most relevant BP/DNA interactions occurs with thymine (Thy). In view of the complex photoreactivity previously observed for dyads containing BP covalently linked to thymidine, the aim of this work is to investigate whether appropriate changes in the nature of the spacer could modulate the intramolecular BP/Thy photoreactivity, resulting in an enhanced selectivity. Accordingly, the photobehavior of a series of dyads derived from BP and Thy, separated by linear linkers of different length, has been investigated by steady-state photolysis, as well as femtosecond and nanosecond transient absorption spectroscopy. Irradiation of the dyads led to photoproducts arising from formal hydrogen abstraction or Paternò-Büchi (PB) photoreaction, with a chemoselectivity that was clearly dependent on the nature of the linking bridge; moreover, the PB process occurred with complete regio-and stereoselectivity. The overall photoreactivity increased with the length of the spacer and correlated well with the rate constants estimated from the BP triplet lifetimes. A reaction mechanism explaining these results is proposed, where key features are the strain associated with the reactive conformations and the participation of triplet exciplexes. ASSOCIATED CONTENTSupporting Information. 1 H and 13 C NMR spectra of the synthesized dyads and intermediates. UV, femtosecond transient absorption and laser flash photolysis spectra and kinetics. X-Ray crystallography data for Ox-D10.

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Quantum chemistry of the excited state: advances in 2020–2021

et al. 2022

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Research on excited-state chemistry using multiconfigurational quantum chemistry (MQC) allows deep analyses of the involved electronic-structure transformations. Overview of the published bibliography in the 2020 and 2021 period shows predominant MQC research on biomedicine and materials science. Significant work on method developments has been also carried out, and applications in atmospheric chemistry are gaining interest as compared to previous years. Topics that are representative of the progress, and are revised herein, are methodology developments for more realistic predictions of UV/Vis absorption and emission spectra, sunlight chemistry on atmospheric modelling, DNA photostability and photosensitisation, DNA reactivity by ionising radiation, chemiluminescence and self-illuminating photosensitisation, DNA repair mechanisms and quantum computing applications in photochemistry.

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Regiochemical memory in the adiabatic photolysis of thymine-derived oxetanes. A combined ultrafast spectroscopic and CASSCF/CASPT2 computational study

Abstract: The photoinduced cycloreversion of oxetanes has been thoroughly investigated in connection with the photorepair of the well-known DNA (6-4) photoproducts. In the present work, the direct photolysis of the two...

Cited by 8 publications

References 42 publications

Mechanistic Studies on the Photochemical Formation and Cleavage of Oxetanes Derived from Pyrimidine Bases

Mechanistic Studies on the Photochemical Formation and Cleavage of Oxetanes Derived from Pyrimidine Bases

Influence of the Linking Bridge on the Photoreactivity of Benzophenone–Thymine Conjugates

Quantum chemistry of the excited state: advances in 2020–2021

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