Charge Transfer Initializes Photoexcited YOYO-1 Intramolecular Rotation and Fluorescent Quenching

2017 ◽  
Author(s):  
Jixin Chen ◽  
Lei Wang ◽  
Joseph R. Pyle
Keyword(s):  
Charge Transfer ◽  
Ground State ◽  
Transient Absorption ◽  
Thermal Relaxation ◽  
Excited Electron ◽  
Transient Absorption Spectroscopy ◽  
Cyanine Dye ◽  
Femtosecond Transient Absorption ◽  
A Charge ◽  
Intramolecular Rotation

YOYO-1 is a commonly used cyanine dye for DNA staining that is fluorescently bright in DNA but very dim in water. The major assumption of its excited electron decay pathway is thermal relaxation via the rotation at a bridging methine that connects the two moieties of the molecule, i.e. photo-isomerization. In this report, we use femtosecond transient absorption spectroscopy to directly measure the excited electron decay, the hole refill, and the hot ground state rise and decay. The data suggest that the first step of the photo-isomerization involves a charge transfer to quench the holes and vibrational activation of the molecules to a hot ground state.

Charge Transfer Initializes Photoexcited YOYO-1 Intramolecular Rotation and Fluorescent Quenching

2017 ◽  
Author(s):  
Jixin Chen ◽  
Lei Wang ◽  
Joseph R. Pyle
Keyword(s):  
Charge Transfer ◽  
Ground State ◽  
Transient Absorption ◽  
Thermal Relaxation ◽  
Excited Electron ◽  
Transient Absorption Spectroscopy ◽  
Cyanine Dye ◽  
Femtosecond Transient Absorption ◽  
A Charge ◽  
Intramolecular Rotation

YOYO-1 is a commonly used cyanine dye for DNA staining that is fluorescently bright in DNA but very dim in water. The major assumption of its excited electron decay pathway is thermal relaxation via the rotation at a bridging methine that connects the two moieties of the molecule, i.e. photo-isomerization. In this report, we use femtosecond transient absorption spectroscopy to directly measure the excited electron decay, the hole refill, and the hot ground state rise and decay. The data suggest that the first step of the photo-isomerization involves a charge transfer to quench the holes and vibrational activation of the molecules to a hot ground state.

Ligand-to-ligand charge transfer in heteroleptic Ir-complexes: comprehensive investigations of its fast dynamics and mechanism

2016 ◽  
Vol 18 (22) ◽  
pp. 15162-15169 ◽  
Author(s):  
Yang-Jin Cho ◽  
So-Yoen Kim ◽  
Minji Cho ◽  
Kyung-Ryang Wee ◽  
Ho-Jin Son ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Ancillary Ligands ◽  
Femtosecond Transient Absorption ◽  
Ligand Charge Transfer ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Charge Transfer Dynamics

The ligand-to-ligand charge transfer dynamics from cyclometalating ligand to ancillary ligands was probed using femtosecond transient absorption spectroscopy after the selective excitations.

scholarly journals Vibrational Excitation Initiates Biomimetic Charge-Coupled Motions in the Electronic Ground State

2020 ◽  
Author(s):  
Gourab Chatterjee ◽  
Ajay Jha ◽  
Alejandro Blanco-Gonzalez ◽  
Vandana Tiwari ◽  
Madushanka Manathunga ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Ground State ◽  
Transient Absorption ◽  
Reaction Pathway ◽  
Vibrational Excitation ◽  
Electronic Configuration ◽  
Electronic Ground State ◽  
Transient Absorption Spectroscopy ◽  
Scotopic Vision ◽  
Electronic Ground

<p>The concerted interplay between reactive nuclear and electronic motions in molecules actuates chemistry. Manipulating reaction pathways to achieve product selectivity via precise control of light-molecule interactions has allured chemists for decades. Yet it remains an elusive challenge in the electronic ground state, where conventional thermally-driven chemistry occurs. Here, we demonstrate that ground-state vibrational excitation of localised bridge modes initiates charge transfer in a donor-bridge-acceptor molecule in solution. The vibrationally-induced change in the ground-state electronic configuration is visualised by transient absorption spectroscopy, involving a mid-infrared pump and a visible probe, and detailed <i>ab initio </i>molecular dynamics simulations. Mapping the potential energy landscape unravels a hitherto undocumented charge-transfer-assisted double-bond isomerization channel in the electronic ground state. The reaction pathway bears remarkable parallels with the thermal isomerization process in rhodopsin, the retinal protein responsible for scotopic vision. Our results illustrate a generic protocol for activating key vibrational modes to drive photo-triggered ground-state reactions and motivate synthetic and catalytic strategies to achieving potentially new chemistry. </p>

scholarly journals Vibrational Excitation Initiates Biomimetic Charge-Coupled Motions in the Electronic Ground State

2020 ◽  
Author(s):  
Gourab Chatterjee ◽  
Ajay Jha ◽  
Alejandro Blanco-Gonzalez ◽  
Vandana Tiwari ◽  
Madushanka Manathunga ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Ground State ◽  
Transient Absorption ◽  
Reaction Pathway ◽  
Vibrational Excitation ◽  
Electronic Configuration ◽  
Electronic Ground State ◽  
Transient Absorption Spectroscopy ◽  
Scotopic Vision ◽  
Electronic Ground

<p>The concerted interplay between reactive nuclear and electronic motions in molecules actuates chemistry. Manipulating reaction pathways to achieve product selectivity via precise control of light-molecule interactions has allured chemists for decades. Yet it remains an elusive challenge in the electronic ground state, where conventional thermally-driven chemistry occurs. Here, we demonstrate that ground-state vibrational excitation of localised bridge modes initiates charge transfer in a donor-bridge-acceptor molecule in solution. The vibrationally-induced change in the ground-state electronic configuration is visualised by transient absorption spectroscopy, involving a mid-infrared pump and a visible probe, and detailed <i>ab initio </i>molecular dynamics simulations. Mapping the potential energy landscape unravels a hitherto undocumented charge-transfer-assisted double-bond isomerization channel in the electronic ground state. The reaction pathway bears remarkable parallels with the thermal isomerization process in rhodopsin, the retinal protein responsible for scotopic vision. Our results illustrate a generic protocol for activating key vibrational modes to drive photo-triggered ground-state reactions and motivate synthetic and catalytic strategies to achieving potentially new chemistry. </p>

Ultrafast charge carrier relaxation and charge transfer processes in CdS/CdTe thin films

2015 ◽  
Vol 17 (26) ◽  
pp. 16760-16766 ◽  
Author(s):  
Bill Pandit ◽  
Ruvini Dharmadasa ◽  
I. M. Dharmadasa ◽  
Thad Druffel ◽  
Jinjun Liu
Keyword(s):  
Thin Films ◽  
Charge Transfer ◽  
Charge Carrier ◽  
Transient Absorption ◽  
Transient Absorption Spectroscopy ◽  
Carrier Relaxation ◽  
Transfer Processes ◽  
Femtosecond Transient Absorption ◽  
Femtosecond Transient Absorption Spectroscopy ◽  
Cdte Thin Films

Charge transfer processes in CdS/CdTe thin films have been studied by femtosecond transient absorption spectroscopy.

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

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

<p></p><p> 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 <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* 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.</p><p></p>

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