scholarly journals Insights into the deactivation of 5-bromouracil after ultraviolet excitation

2017 ◽  
Vol 375 (2092) ◽  
pp. 20160202 ◽  
Author(s):  
Francesca Peccati ◽  
Sebastian Mai ◽  
Leticia González
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Surface Hopping ◽  
Ultraviolet Excitation ◽  
Quantum Chemistry Calculations ◽  
Electronic Structure Methods ◽  
Dna Strands ◽  
Potential Applications ◽  
Adiabatic Dynamics ◽  
Dynamics Simulations

5-Bromouracil is a nucleobase analogue that can replace thymine in DNA strands and acts as a strong radiosensitizer, with potential applications in molecular biology and cancer therapy. Here, the deactivation of 5-bromouracil after ultraviolet irradiation is investigated in the singlet and triplet manifold by accurate quantum chemistry calculations and non-adiabatic dynamics simulations. It is found that, after irradiation to the bright ππ * state, three main relaxation pathways are, in principle, possible: relaxation back to the ground state, intersystem crossing (ISC) and C–Br photodissociation. Based on accurate MS-CASPT2 optimizations, we propose that ground-state relaxation should be the predominant deactivation pathway in the gas phase. We then employ different electronic structure methods to assess their suitability to carry out excited-state dynamics simulations. MRCIS (multi-reference configuration interaction including single excitations) was used in surface hopping simulations to compute the ultrafast ISC dynamics, which mostly involves the 1 n O π * and 3 ππ * states. This article is part of the themed issue ‘Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces’.

Excited state dynamics and time-resolved photoelectron spectroscopy of para-xylylene

2018 ◽  
Vol 212 ◽  
pp. 83-100 ◽  
Author(s):  
Kevin Issler ◽  
Anja Röder ◽  
Florian Hirsch ◽  
Lionel Poisson ◽  
Ingo Fischer ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Time Scale ◽  
Time Resolved ◽  
Surface Hopping ◽  
Excited State Dynamics ◽  
Ultraviolet Excitation ◽  
Step Mechanism

We investigated the excited-state dynamics of para-xylylene using a combination of field-induced surface hopping simulations and time-resolved photoionisation experiments. Ultraviolet excitation is followed by nonadiabatic relaxation to the ground state in a two-step mechanism on the sub-ps time scale.

Non-adiabatic dynamics simulation exploration of the wavelength-dependent photoinduced relaxation mechanism of trans-N-1-methyl-2-(tolylazo) imidazole in the gas phase

RSC Advances ◽  
2016 ◽  
Vol 6 (69) ◽  
pp. 64323-64331 ◽  
Author(s):  
Li Zhao ◽  
Pan-Wang Zhou ◽  
Guang-Jiu Zhao
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Excited States ◽  
Relaxation Mechanism ◽  
Dynamics Simulation ◽  
Relaxation Dynamics ◽  
Surface Hopping ◽  
Electronic Excited States ◽  
Comprehensive Picture ◽  
Adiabatic Dynamics

A comprehensive picture of the photoinduced non-adiabatic relaxation dynamics of trans-N-1-methyl-2-(tolylazo) imidazole (trans-MTAI) in different electronic excited states has been revealed using the on-the-fly surface hopping method at the ab initio CASSCF level.

scholarly journals Dynamics of electronically excited states in the eumelanin building block 5,6-dihydroxyindole

2019 ◽  
Vol 21 (15) ◽  
pp. 8152-8160 ◽  
Author(s):  
Stuart W. Crane ◽  
Omair Ghafur ◽  
Thomas Y. Cowie ◽  
Anita G. Lindsay ◽  
James O. F. Thompson ◽  
...  
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Thermal Desorption ◽  
Building Block ◽  
Electronically Excited States ◽  
Ultraviolet Excitation ◽  
Phase Study ◽  
Electronically Excited ◽  
Adiabatic Dynamics

Laser-based thermal desorption facilitates the first gas-phase study of ultrafast non-adiabatic dynamics operating in 5,6-dihydroxyinole following ultraviolet excitation.

Mechanistic analysis of light-driven overcrowded alkene-based molecular motors by multiscale molecular simulations

2021 ◽  
Vol 23 (14) ◽  
pp. 8525-8540
Author(s):  
Mudong Feng ◽  
Michael K. Gilson
Keyword(s):  
Molecular Dynamics ◽  
Excited State ◽  
Molecular Dynamics Simulations ◽  
Ground State ◽  
Molecular Motors ◽  
Motor Performance ◽  
Molecular Simulations ◽  
Mechanistic Analysis ◽  
Dynamics Simulations ◽  
Shed Light

Ground-state and excited-state molecular dynamics simulations shed light on the rotation mechanism of small, light-driven molecular motors and predict motor performance. How fast can they rotate; how much torque and power can they generate?

scholarly journals Negative ion photoelectron spectroscopy confirms the prediction that D3h carbon trioxide (CO3) has a singlet ground state

2016 ◽  
Vol 7 (2) ◽  
pp. 1142-1150 ◽  
Author(s):  
David A. Hrovat ◽  
Gao-Lei Hou ◽  
Bo Chen ◽  
Xue-Bin Wang ◽  
Weston Thatcher Borden
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Photoelectron Spectroscopy ◽  
Radical Anion ◽  
Negative Ion ◽  
Singlet Ground State

The CO3 radical anion (CO3˙−) has been formed by electrospraying carbonate dianion (CO32−) into the gas phase.

scholarly journals Nonadiabatic dynamics with quantum nuclei: simulating charge transfer with ring polymer surface hopping

2020 ◽  
Vol 221 ◽  
pp. 501-525 ◽  
Author(s):  
Soumya Ghosh ◽  
Samuele Giannini ◽  
Kevin Lively ◽  
Jochen Blumberger
Keyword(s):  
Charge Transfer ◽  
Polymer Surface ◽  
Nonadiabatic Dynamics ◽  
Surface Hopping ◽  
Different Temperatures ◽  
Ring Polymer ◽  
Adiabatic Dynamics

Exploring effects of quantizing nuclei in non-adiabatic dynamics for simulating charge transfer in a dimer of “ethylene-like-molecules” at different temperatures.

scholarly journals Super-electrophiles of Tri- and Tetra-Anions Stabilized by Selected Terminal Groups and Their Role in Binding Noble Gas atoms

2021 ◽  
Author(s):  
MingMin Zhong ◽  
Hong Fang ◽  
Deepika Deepika ◽  
Purusottam Jena
Keyword(s):  
Gas Phase ◽  
Noble Gas ◽  
Atomic Clusters ◽  
Weakly Coordinating Anions ◽  
Multiply Charged ◽  
Potential Applications ◽  
Weakly Coordinating

Stabilization of multiply-charged atomic clusters in the gas phase has been a topic of great interest not only because of their potential applications as weakly-coordinating anions, but also for their...

scholarly journals Development of a New Sr-O Parameterization to Describe the Influence of SrO on Iron-Phosphate Glass Structural Properties Using Molecular Dynamics Simulations

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4326
Author(s):  
Pawel Goj ◽  
Aleksandra Wajda ◽  
Pawel Stoch
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Interatomic Potential ◽  
Glass Structure ◽  
Ion Pairs ◽  
Glass Network ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Potential Applications ◽  
Dynamics Simulations

Iron-phosphate glasses, due to their properties, have many potential applications. One of the most promising seems to be nuclear waste immobilization. Radioactive 90Sr isotope is the main short-lived product of fission and, due to its high solubility, it can enter groundwater and pose a threat to the environment. On the other hand, Sr is an important element in hard tissue metabolic processes, and phosphate glasses containing Sr are considered bioactive. This study investigated the effect of SrO addition on a glass structure of nominal 30Fe2O3-70P2O5 chemical composition using classical molecular dynamics simulations. To describe the interaction between Sr-O ion pairs, new interatomic potential parameters of the Buckingham-type were developed and tested for crystalline compounds. The short-range structure of the simulated glasses is presented and is in agreement with previous experimental and theoretical studies. The simulations showed that an increase in SrO content in the glass led to phosphate network depolymerization. Analysis demonstrated that the non-network oxygen did not take part in the phosphate network depolymerization. Furthermore, strontium aggregation in the glass structure was observed to lead to the non-homogeneity of the glass network. It was demonstrated that Sr ions prefer to locate near to Fe(II), which may induce crystallization of strontium phosphates with divalent iron.

The Dielectric Discharge as an Efficient Generator of Active Nitrogen for Chemiluminescence and Analysis

1983 ◽  
Vol 37 (6) ◽  
pp. 545-552 ◽  
Author(s):  
John Kishman ◽  
Eric Barish ◽  
Ralph Allen
Keyword(s):  
Gas Phase ◽  
Ground State ◽  
Band System ◽  
Electrothermal Atomization ◽  
Characteristic Radiation ◽  
Gaseous Species ◽  
Vibrationally Excited ◽  
Active Nitrogen ◽  
Excited Species ◽  
Intense Emission

A predominantly blue “active nitrogen” afterglow was generated in pure flowing nitrogen or in air by using a dielectric discharge at pressures from 1 to 20 Torr. The afterglow contains triplet state molecules and vibrationally excited ground state molecules. These species are produced directly by electron impact without the formation and recombination of nitrogen atoms. The most intense emission is the N2 second positive band system. The N2 first positive and N2+ first negative systems are also observed. The spectral and electrical properties of this discharge are discussed in order to establish guidelines for the analytical use of the afterglow for chemiluminescence reactions. The metastatic nitrogen efficiently transfers its energy to atomic and molecular species which are introduced into the gas phase and these excited species emit characteristic radiation. The effects of electrothermal atomization of Zn and the introduction of gaseous species (e.g., NO) on the afterglow are described.

Nonadiabatic dynamics simulation of keto isocytosine: a comparison of dynamical performance of different electronic-structure methods

2017 ◽  
Vol 19 (29) ◽  
pp. 19168-19177 ◽  
Author(s):  
Deping Hu ◽  
Yan Fang Liu ◽  
Andrzej L. Sobolewski ◽  
Zhenggang Lan
Keyword(s):  
Electronic Structure ◽  
Dynamics Simulation ◽  
Nonadiabatic Dynamics ◽  
Electronic Structure Methods ◽  
Reaction Channels ◽  
Dynamics Simulations

Different reaction channels are obtained in the nonadiabatic dynamics simulations of isocytosine at CASSCF and ADC(2) levels.

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