RT Journal Article
T1 Excited-State Proton and Charge Transfer in Protonated Amino and Methylated Derivatives of 2-(2′-Hydroxyphenyl)benzimidazole
A1 Ríos Vázquez, Sonia
A1 Pérez Lustres, José Luis
A1 Rodríguez-Prieto, Flor
A1 Mosquera González, Manuel
A1 Ríos Rodríguez, María del Carmen
AB We studied the excited-state behavior of a family of mono- and diprotonated derivatives of 2-phenylbenzimidazole in different solvents, using steady-state and time-resolved fluorescence spectroscopy. The species investigated were 2-(4′-amino-2′-hydroxyphenyl)benzimidazole (1), the diethylamino analogue 2-(4′-N,N-diethylamino-2′-hydroxyphenyl)benzimidazole (2) and its N-methylated derivative 1-methyl-2-(4′-N,N-diethylamino-2′-hydroxyphenyl)benzimidazole (3). The O-methoxy derivatives of 2 and 3 (2-OMe and 3-OMe), and the simpler models 2-phenylbenzimidazole (4) and its 4′-amino (5) and 4′-dimethylamino (6) derivatives were also studied. We found that the dications of 1, 2, and 3 (protonated at the benzimidazole N3 and at the amino group) were strong photoacids, which were deprotonated at the hydroxyl group upon excitation in aqueous solution (totally for 2 and 3) to give a tautomer of the ground-state monocation. In contrast, no photodissociation was observed for the monocations of these species. Instead, some of the monocations studied behaved as molecular rotors, for which electronic excitation led to a twisted intramolecular charge transfer (TICT) state. The monocations of 2, 3, 2-OMe, 3-OMe, and 6, protonated at the benzimidazole N3, experienced a polarity- and viscosity-dependent radiationless deactivation associated with a large-amplitude rotational motion. We propose that this process is connected to an intramolecular charge transfer from the dimethylaminophenyl or diethylaminophenyl moiety (donor) to the protonated benzimidazole group (acceptor) of the excited monocation, which yields a twisted charge-transfer species. No fluorescence from this species was detected except for 3 and 3-OMe in low-viscosity solvents
PB American Chemical Society
SN 1520-6106
YR 2015
FD 2015
LK http://hdl.handle.net/10347/17052
UL http://hdl.handle.net/10347/17052
LA eng
NO Ríos Vázquez, S., Pérez Lustres, J., Rodríguez-Prieto, F., Mosquera, M., & Ríos Rodríguez, M. (2015). Excited-State Proton and Charge Transfer in Protonated Amino and Methylated Derivatives of 2-(2′-Hydroxyphenyl)benzimidazole. The Journal Of Physical Chemistry B, 119(6), 2475-2489. doi: 10.1021/jp507917u
NO This is the peer-reviewed version of the following article:The Journal of Physical Chemistry B 2015, 119, 2475–2489, DOI: 10.1021/jp507917u, which has been published in final form at https://pubs.acs.org/doi/abs/10.1021/jp507917u.This article may be used for non-commercial purposes only
NO We are indebted to the European Regional Development Fund, the Spanish Ministry of Economy and Competitiveness (Grant CTQ2010-17835), and the Xunta de Galicia (Grants GPC2013/052, CN2012/314, and EM2012/091) for financial support of our work. S.R. and J.L.P.L. are thankful for a MEC-FPU fellowship and a “Ramón y Cajal” contract, respectively
DS Minerva
RD 23 abr 2026