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Altering the Coordination of Iron Porphyrins by Ionic Liquid Nanodomains in Mixed Solvent Systems
Author(s) -
Atifi Abderrahman,
Ryan Michael D.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201701540
Subject(s) - ionic liquid , chemistry , solvent , reactivity (psychology) , solvation , delocalized electron , porphyrin , ionic bonding , redox , electron paramagnetic resonance , inorganic chemistry , coordination complex , photochemistry , ion , metal , organic chemistry , catalysis , nuclear magnetic resonance , medicine , physics , alternative medicine , pathology
The solvent environment around iron porphyrin complexes was examined using mixed molecular/RTIL (room temperature ionic liquid) solutions. The formation of nanodomains in these solutions provides different solvation environments for substrates that could have significant impact on their chemical reactivity. Iron porphyrins (Fe(P)), whose properties are sensitive to solvent and ligation changes, were used to probe the molecular/RTIL environment. The addition of RTILs to molecular solvents shifted the redox potentials to more positive values. When there was no ligation change upon reduction, the shift in the E ° values were correlated to the Gutmann acceptor number, as was observed for other porphyrins with similar charge changes. As %RTIL approached 100 %, there was insufficient THF to maintain coordination and the E ° values were much more dependent upon the %RTIL. In the case of Fe III (P)(Cl), the shifts in the E ° values were driven by the release of the chloride ion and its strong attraction to the ionic liquid environment. The spectroscopic properties and distribution of the Fe II and Fe I species into the RTIL nanodomains were monitored with visible spectroelectrochemistry, 19 F NMR and EPR spectroscopy. This investigation shows that coordination and charge delocalization (metal versus ligand) in the metalloporphyrins redox products can be altered by the RTIL fraction in the solvent system, allowing an easy tuning of their chemical reactivity.