Finite-temperature Wigner phase-space sampling and temperature effects on the excited-state dynamics of 2-nitronaphthalene

Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived 1nOπ* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived 3ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.

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Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

10.26434/chemrxiv.7860023.v1 ◽

2019 ◽

Author(s):

Matthew M. Brister ◽

Carlos Crespo-Hernández

Keyword(s):

Excited State ◽

Excited States ◽

Ground State ◽

Transient Absorption ◽

Electronic Energy ◽

Transient Absorption Spectroscopy ◽

Electronic Relaxation ◽

Vibrationally Excited ◽

Excited State Dynamics ◽

Π State

Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived 1nOπ* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived 3ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.

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Ultrafast excited state dynamics and light-switching of [Ru(phen)2(dppz)]2+ in G-quadruplex DNA

Communications Chemistry ◽

10.1038/s42004-021-00507-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Chunfan Yang ◽

Qian Zhou ◽

Zeqing Jiao ◽

Hongmei Zhao ◽

Chun-Hua Huang ◽

...

Keyword(s):

Excited State ◽

State Formation ◽

Rational Design ◽

Bound Water ◽

Binding Modes ◽

Relaxation Dynamics ◽

Dark State ◽

Excited State Dynamics ◽

G Quadruplex ◽

Mechanistic Basis

AbstractThe triplet metal to ligand charge transfer (3MLCT) luminescence of ruthenium (II) polypyridyl complexes offers attractive imaging properties, specifically towards the development of sensitive and structure-specific DNA probes. However, rapidly-deactivating dark state formation may compete with 3MLCT luminescence depending on different DNA structures. In this work, by combining femtosecond and nanosecond pump-probe spectroscopy, the 3MLCT relaxation dynamics of [Ru(phen)2(dppz)]2+ (phen = 1,10-phenanthroline, dppz = dipyridophenazine) in two iconic G-quadruplexes has been scrutinized. The binding modes of stacking of dppz ligand on the terminal G-quartet fully and partially are clearly identified based on the biexponential decay dynamics of the 3MLCT luminescence at 620 nm. Interestingly, the inhibited dark state channel in ds-DNA is open in G-quadruplex, featuring an ultrafast picosecond depopulation process from 3MLCT to a dark state. The dark state formation rates are found to be sensitive to the content of water molecules in local G-quadruplex structures, indicating different patterns of bound water. The unique excited state dynamics of [Ru(phen)2(dppz)]2+ in G-quadruplex is deciphered, providing mechanistic basis for the rational design of photoactive ruthenium metal complexes in biological applications.

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Excited-state dynamics of guanosine in aqueous solution revealed by time-resolved photoelectron spectroscopy: experiment and theory

Physical Chemistry Chemical Physics ◽

10.1039/c5cp04394h ◽

2015 ◽

Vol 17 (47) ◽

pp. 31978-31987 ◽

Cited By ~ 8

Author(s):

Franziska Buchner ◽

Berit Heggen ◽

Hans-Hermann Ritze ◽

Walter Thiel ◽

Andrea Lübcke

Keyword(s):

Aqueous Solution ◽

Excited State ◽

Photoelectron Spectroscopy ◽

Relaxation Dynamics ◽

Time Resolved ◽

Excited State Dynamics ◽

Spectroscopy Experiment

Time-resolved photoelectron spectroscopy is performed on aqueous guanosine solution to study its excited-state relaxation dynamics.

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Investigation of ultrafast excited state dynamics of 2,2′,4,4′,6,6′-hexanitrostilbene using femtosecond transient absorption spectroscopy

RSC Advances ◽

10.1039/c4ra08305a ◽

2014 ◽

Vol 4 (104) ◽

pp. 60382-60385 ◽

Cited By ~ 4

Author(s):

Genbai Chu ◽

Min Shui ◽

Ying Xiong ◽

Jing Yi ◽

Kemei Cheng ◽

...

Keyword(s):

Excited State ◽

Excited States ◽

Absorption Spectroscopy ◽

Transient Absorption ◽

Transient Absorption Spectroscopy ◽

Excited State Dynamics ◽

Femtosecond Transient Absorption ◽

Femtosecond Transient Absorption Spectroscopy

A study on the dynamics and structures of the excited states of 2,2′,4,4′,6,6′-hexanitrostilbene shows equilibrium between vibrationally hot S1 (S*1) and S1 states with lifetimes of 0.8 and 6 ps, respectively.

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Vibronic coupling in the excited-states of carotenoids

Physical Chemistry Chemical Physics ◽

10.1039/c5cp07542d ◽

2016 ◽

Vol 18 (16) ◽

pp. 11443-11453 ◽

Cited By ~ 12

Author(s):

Takeshi Miki ◽

Tiago Buckup ◽

Marie S. Krause ◽

June Southall ◽

Richard J. Cogdell ◽

...

Keyword(s):

Excited State ◽

Excited States ◽

Vibronic Coupling ◽

Relaxation Dynamics ◽

Dark State ◽

Electronic Excited States

The ultrafast femtochemistry of carotenoids is governed by the interaction between electronic excited states, which has been explained by the relaxation dynamics within a few hundred femtoseconds from the lowest optically allowed excited state S2to the optically dark state S1.

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EXCITED STATE DYNAMICS OF RETINAL PROTEINS AS STUDIED BY FOURIER TRANSFORM OF OPTICAL ABSORPTION SPECTRUM—I. DEVELOPMENT OF ANALYTICAL METHOD

Photochemistry and Photobiology ◽

10.1111/j.1751-1097.1992.tb09720.x ◽

1992 ◽

Vol 56 (6) ◽

pp. 977-987 ◽

Cited By ~ 8

Author(s):

Toshiaki Kakitani ◽

Yasuyo Hatano ◽

Yoshinori Shichida ◽

Yasushi Imamoto ◽

Fumio Tokunaga ◽

...

Keyword(s):

Absorption Spectrum ◽

Fourier Transform ◽

Excited State ◽

Optical Absorption ◽

Optical Absorption Spectrum ◽

Analytical Method ◽

Excited State Dynamics ◽

Retinal Proteins

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Excited State Dynamics of 7-Deazaguanosine and Guanosine 5’ Monophosphate

10.26434/chemrxiv.13262681.v2 ◽

2021 ◽

Author(s):

Sarah E. Krul ◽

Sean J. Hoehn ◽

Karl Feierabend ◽

Carlos Crespo-Hernández

Keyword(s):

Excited State ◽

Ground State ◽

Internal Conversion ◽

Transient Absorption ◽

Transient Absorption Spectroscopy ◽

Water Mixture ◽

Relaxation Dynamics ◽

Similar Time ◽

Excited State Dynamics ◽

Computational Calculations

Minor structural modifications to the DNA and RNA nucleobases have a significant effect on their excited state dynamics and electronic relaxation pathways. In this study, the excited state dynamics of 7-deazaguanosine and guanosine 5’-monophosphate are investigated in aqueous and in a mixture of methanol and water using femtosecond broadband transient absorption spectroscopy following excitation at 267 nm. The transient spectra are collected using photon densities that ensure no parasitic multiphoton-induced signal from solvated electrons. The data can be fit satisfactorily using a two- or three-component kinetic model. By analyzing the results from steady-state, time-resolved, computational calculations, and the methanol-water mixture, the following general relaxation mechanism is proposed for both molecules, Lb ® La ® 1ps*(ICT) ® S0, where the 1ps*(ICT) stands for an intramolecular charge transfer excited singlet state with significant ps* character. In general, longer lifetimes for internal conversion are obtained for 7-deazaguanosine compared to guanosine 5’-monophosphate. Internal conversion of the 1ps*(ICT) state to the ground state occurs on a similar time scale of a few picoseconds in both molecules. Collectively, the results demonstrate that substitution of a single nitrogen for a methine (C-H) group at position seven of the guanine moiety stabilizes the 1pp* Lb and La states and alter the topology of their potential energy surfaces in such a way that the relaxation dynamics in 7-deazaguanosine are slowed down compared to those in guanosine 5’-monophosphate but not for the internal conversion of 1ps*(ICT) state to the ground state.

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Excited State Dynamics of 7-Deazaguanosine and Guanosine 5’ Monophosphate

10.26434/chemrxiv.13262681 ◽

2021 ◽

Author(s):

Sarah E. Krul ◽

Sean J. Hoehn ◽

Karl Feierabend ◽

Carlos Crespo-Hernández

Keyword(s):

Excited State ◽

Ground State ◽

Internal Conversion ◽

Transient Absorption ◽

Transient Absorption Spectroscopy ◽

Water Mixture ◽

Relaxation Dynamics ◽

Similar Time ◽

Excited State Dynamics ◽

Computational Calculations

Minor structural modifications to the DNA and RNA nucleobases have a significant effect on their excited state dynamics and electronic relaxation pathways. In this study, the excited state dynamics of 7-deazaguanosine and guanosine 5’-monophosphate are investigated in aqueous and in a mixture of methanol and water using femtosecond broadband transient absorption spectroscopy following excitation at 267 nm. The transient spectra are collected using photon densities that ensure no parasitic multiphoton-induced signal from solvated electrons. The data can be fit satisfactorily using a two- or three-component kinetic model. By analyzing the results from steady-state, time-resolved, computational calculations, and the methanol-water mixture, the following general relaxation mechanism is proposed for both molecules, Lb ® La ® 1ps*(ICT) ® S0, where the 1ps*(ICT) stands for an intramolecular charge transfer excited singlet state with significant ps* character. In general, longer lifetimes for internal conversion are obtained for 7-deazaguanosine compared to guanosine 5’-monophosphate. Internal conversion of the 1ps*(ICT) state to the ground state occurs on a similar time scale of a few picoseconds in both molecules. Collectively, the results demonstrate that substitution of a single nitrogen for a methine (C-H) group at position seven of the guanine moiety stabilizes the 1pp* Lb and La states and alter the topology of their potential energy surfaces in such a way that the relaxation dynamics in 7-deazaguanosine are slowed down compared to those in guanosine 5’-monophosphate but not for the internal conversion of 1ps*(ICT) state to the ground state.

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