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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Photophysics of Emissive C-tz[Isothiazolo-Cytidine] and U-tz[Isothiazolo-Uridine] Pyrimidine Analogues

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Valverde, Danillo [1] ; Sanches de Araujo, Adalberto Vasconcelos [2] ; Canuto, Sylvio [1] ; Borin, Antonio Carlos [2]
Total Authors: 4
[1] Univ Sao Paulo, Inst Phys, Rua Matao 1371, BR-05508090 Sao Paulo, SP - Brazil
[2] Univ Sao Paulo, Inst Chem, Dept Fundamental Chem, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil
Total Affiliations: 2
Document type: Journal article
Source: CHEMPHOTOCHEM; v. 3, n. 9, SI, p. 916-924, SEP 2019.
Web of Science Citations: 0

The C-tz and U-tz emissive properties were investigated with the MS-CASPT2 method and CASSCF/CASPT2 protocol, with inclusion of solvent effects with the aid of the PCM and Sequential QM/MM, the Free Energy Gradient methods. Theoretical vertical emission energies and Stokes shifts, using the ASEC-FEG method, are in a good agreement with the experimental data, within the expected accuracy of CASPT2 method. Their emissive properties can be understood in analogy to the photophysical behaviour of the canonical uracil and cytosine pyrimidine nucleobases, for which the twisting of the C5C6 bond is the key for understanding their ultrashort radiationless decay times. For both C-tz and U-tz, the computed photophysical deactivation pathway, shows that the bright state 1(pi pi{*}) goes directly to a minimum structure on its potential energy hypersurface (1(pi pi{*})min), from where no conical intersection with the ground state can be reached, due to the steric hindrance of the C5C6 position, which forms the bridge between the rings in both molecules. Solvent effects place the conical intersection in higher energy region, reinforcing their emissive nature. (AU)

FAPESP's process: 17/02612-4 - Dynamics of excited states and spectroscopic properties of natural and synthetic DNA and RNA derivatives in solvent environment
Grantee:Danillo Pires Valverde
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 14/50983-3 - INCT 2014: complex fluids
Grantee:Antonio Martins Figueiredo Neto
Support type: Research Projects - Thematic Grants