Ruthenium and chromium complexes bearing pH-indicators as the η6-arene ligand: Synthesis, characterization, and protonation behavior
作者:Miyuki Hirasa、Akiko Inagaki、Munetaka Akita
DOI:10.1016/j.jorganchem.2006.07.046
日期:2007.1
A series of ruthenium and chromium complexes bearing pH indicators as the eta(6)-arene ligand, (eta(6)-X)(MLn)(y) [X = methyl yellow, crystal violet lactone, phenolphthalein; MLn = RuCp*(+), RuCl2(L), Cr(CO)(3); y = 1, 2] is prepared and characterized by spectroscopic and crystallographic methods. Of the plural arene rings in the indicators, a specific arene ring can be successfully coordinated to the metal center in a selective manner under appropriate conditions (i.e. use of the precursors of different oxidation states and reaction with the non-protonated and protonated pH indicator). The obtained indicator complexes show halochromic behavior depending on pH as observed for the parent molecules but the transition pH ranges are shifted to the more acidic side because of the attachment of the electron-withdrawing metal fragments, which decrease the basicity of the attached pH indicators. (c) 2006 Elsevier B.V. All rights reserved.
Azaferrocenophanes with Azobenzene‐Containing Ligands − Protonation and Electrochemical Oxidation of the Molecule Influences the Absorption Spectra and
<i>cis</i>
−
<i>trans</i>
Isomerization of the Azobenzene Group
trans-azobenzene group of 4 and 5 appear at 442 and 426 nm, respectively, in toluene. Photoirradiation of solutions of 4 and 5 at 420 nm causes partial isomerization of the trans-azobenzene group to cis-azobenzene and reaches a photostationary state. The compounds at the photostationary state undergo thermal isomerization of the cis-azobenzene group to the trans isomer. The isomerization after one-electron