Notes
Dissolution State in 1,10-phenanthroline in a Nitrobenzene Solution Using ESI-MS
2021 Volume 70 Issue 4.5 Pages 277-282
Details
2021 Volume 70 Issue 4.5 Pages 277-282
Ferrous ion (Fe(II)) is known to form a stable [Fe(phen)3]2+ complex with 1,10-phenanthroline (phen) in an aqueous solution. Here, we report on the complex formation of Fe(II) with phen in a nitrobenzene (NB) solution containing sodium perchlorate (NaClO4). A sample solution composed of 50 μmol L−1 of phen, 5 μmol L−1 FeCl2 and 50 μmol L−1 of NaClO4 was prepared. The absorption band of [Fe(phen)3]2+ formed in the NB solution was observed at 510-520 nm. The sample solution was extracted with a 1 : 1 volume of NB and water phases. The NB solution extracted was then measured by ESI-MS with methanol (MeOH) as a mobile phase to characterize the solution state of Fe(II), phen, and NB. [Fe(phen)3]2+, [Fe(phen)2-MeOH]2+, and [Fe(phen)2]2+ were identified. These Fe(II)-related species probably originate from [Fe(phen)3]2+ and partly from [Fe(phen)2]2+ in a NB solution, and cause the broadening of the absorption band at 510-520 nm. In the gas phase, [Fe(phen)2]2+ is predominant, but unstable and tends to form stable adducts with either one molecule of NB or MeOH. And Na+ might come from an ESI-MS equipment and adducts with phen. Interestingly, Na+ related complexes, such as [Na(phen)]+ and [Na(phen)2]+ were also formed in a NB solution in 3 days. In ionization process of ESI-MS, polymerization of phen is easily occurred, and more phen polymerization is promoted with Fe.
