Investigation on solvation and protonation of meso-tetrakis(p-sulfonatophenyl)porphyrin in imidazolium-based ionic liquids by spectroscopic methods.

The solvation and protonation of the meso-tetrakis(p-sulfonatophenyl)porphyrin (TPPS) were investigated by spectroscopic methods in pure or mixed imidazolium-based ionic liquids: 1-butyl-3-methyl-imidazolium terafluoroborate ([MBIM]BF(4)), 1-butylimidazolium terafluoroborate ([HBIM]BF(4)), 1-butyl-imidazolium dodecylalkylbenzenesulfonate ([HBIM]DS), 1-butyl-imidazolium p-toluenesulfonate ([HBIM]TS) and 1-butyl-imidazolium methylsulfonate ([HBIM]MS). Compared with absorption properties of TPPS in aqueous solution, Soret band of TPPS monomer was obviously red-shifted in the ionic liquids, while special absorption of TPPS J-aggregates was located at higher energy level, 483 nm and 702 nm, in protonic ionic liquids (PILs) [HBIM]BF(4). Next, the protonation of TPPS in aprotonic ionic liquids (AILs, i.