Jump to main content
Jump to site search

1IL and 3MLCT Excited States Modulated by H+: Structure and Photophysical Properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br]


The reaction of 2-bromo-5-(1H-pyrazol-1-yl)pyrazine (LI) and bromotricarbonyl(tetrahydrofuran)-rhenium(I) dimer leads to the monometallic complex [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br] (I), which displays a non-regular octahedral geometry around ReI center, a fac-correlation for carbonyls, with pyrazine and pyrazolyl rings highly coplanar. I experiences one irreversible oxidation at Ep,a = 1.067 V and two irreversible reductions at Ep,c = -1.445 V and -1.675 V. DFT supports the oxidation is a metal-centered processes but the first reduction wave should be a ligand-centered processes. Comparison with related complexes suggest the second reduction is metal centered (ReI/Re0) .Three absorptions bands were observed for I around 260, 315 and 400 nm, the first two were assigned to intraligand (IL) π → π* transitions while the band around 400 nm corresponds to a metal-to-ligand charge transfer (MLCT) transition. Excitation of I at 280 nm leads to two emission bands at 360 nm and 640 nm, the first one attributed to the 1IL transition and the second to 3MLCT. The 3MLCT emission decays with lifetimes of 17 and 44 ns in MeCN and DCM, respectively. Addition of trifluoroacetic acid to the solution leads to its reaction with the 3MLCT excited state, giving rise to a long-lived and very oxygen sensitive specie, 3ILH+. This behaviour makes I potential sensor for protons and possibly other cations in solution.

Back to tab navigation

Supplementary files

Publication details

The article was received on 16 Aug 2018, accepted on 11 Jan 2019 and first published on 11 Jan 2019

Article type: Paper
DOI: 10.1039/C8NJ04196B
Citation: New J. Chem., 2019, Accepted Manuscript
  •   Request permissions

    1IL and 3MLCT Excited States Modulated by H+: Structure and Photophysical Properties of [(2-bromo-5-(1H-pyrazol-1-yl)pyrazine)Re(CO)3Br]

    N. A. Pizarro, M. Saldias, N. Guzmán, C. Sandoval-Altamirano, S. Kahlal, J. Saillard, J. Hamon and A. Vega, New J. Chem., 2019, Accepted Manuscript , DOI: 10.1039/C8NJ04196B

Search articles by author