Excited-State Dynamics of Thienoguanosine, an Isomorphic Highly Fluorescent Analogue of Guanosine(16 visite) Martinez-fernandez L, Gavvala K, Sharma R, Didier P, Richert L, Segarra Marti J, Mori M, Mely Y, Improta R
Chemistry (ISSN: 0947-6539linking), 2019 May 28; 25(30): 7375-7386.
Tipo di articolo: Journal Article
Impact factor: 5.16, Impact factor a 5 anni: 5.477
Url: Non disponibile.
Parole chiave: Dna, Td-Dft Calculations, Density Functional Calculations, Fluorescence Spectroscopy, Nucleobases, Solvent Effects
*** IBB - CNR *** Departamento de Quimica, Facultad de Ciencias, Modulo13, Universidad Autonoma de Madrid, Campus de Excelencia UAM-CSIC, Cantoblanco, 28049 Madrid, Spain. Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Universite de Strasbourg, Faculte de pharmacie, 74 route du Rhin, 67401, Illkirch, France. Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, 80 Wood Lane, W12 0BZ, London, UK. Dipartimento di Biotecnologie, Chimica e Farmacia, Universita degli Studi di Siena, 53100, Siena, Italy. Consiglio Nazionale delle Ricerche, Istituto Biostrutture e Bioimmagini, Via Mezzocannone 16, 80134, Napoli, Italy.
Thienoguanosine ((th) G) is an isomorphic analogue of guanosine with promising potentialities as fluorescent DNA label. As a free probe in protic solvents, (th) G exists in two tautomeric forms, identified as the H1, being the only one observed in nonprotic solvents, and H3 keto-amino tautomers. We herein investigate the photophysics of (th) G in solvents of different polarity, from water to dioxane, by combining time-resolved fluorescence with PCM/TD-DFT and CASSCF calculations. Fluorescence lifetimes of 14.5-20.5 and 7-13 ns were observed for the H1 and H3 tautomers, respectively, in the tested solvents. In methanol and ethanol, an additional fluorescent decay lifetime ( approximately 3 ns) at the blue emission side (lambda approximately 430 nm) as well as a 0.5 ns component with negative amplitude at the red edge of the spectrum, typical of an excited-state reaction, were observed. Our computational analysis explains the solvent effects observed on the tautomeric equilibrium. The main radiative and nonradiative deactivation routes have been mapped by PCM/TD-DFT calculations in solution and CASSCF in the gas phase. The most easily accessible conical intersection, involving an out-of plane motion of the sulfur atom in the five-membered ring of (th) G, is separated by a sizeable energy barrier (>/=0.4 eV) from the minimum of the spectroscopic state, which explains the large experimental fluorescence quantum yield.<br>
58 Records (58 escludendo Abstract e Conferenze). Impact factor totale: 312.889 (312.889 escludendo Abstract e Conferenze). Impact factor a 5 anni totale: 330.925 (330.925 escludendo Abstract e Conferenze).