Effect of Ionic Liquid on J-Aggregation ofmeso-Tetrakis(4-sulfonatophenyl)porphyrin within Aqueous Mixtures of Poly(ethylene glycol)

Abstract

Aqueous mixtures of poly(ethylene glycol) (PEG) of different compositions offer widely varying physicochemical properties that may support porphyrin aggregation. Aggregation behavior of a common water-soluble porphyrin, meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS), is investigated within aqueous PEG mixtures constituted of PEGs of average molecular weights 200 (PEG200), 400 (PEG400), 600 (PEG600), and 1000 (PEG1000) using UV-vis molecular absorbance, steady-state fluorescence, and resonance light scattering techniques. No aggregation of TPPS is observed in neat PEGs; addition of 10 wt % water to PEG at pH 1.0 is found to trigger TPPS into significant J-aggregation. The J-aggregation is observed to be most efficient within an aqueous mixture of 90 wt % PEG1000 at pH 1.0. The effect of ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF(6)]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF(4)]), as additives on the J-aggregation efficiency of TPPS within aqueous mixtures of PEG400 at pH 1.0 is investigated and compared with the effect of salts NaCl, NaPF(6), and NaBF(4) as additives on the J-aggregation of TPPS under the same conditions. In an aqueous mixture of 10 wt % PEG400 at pH 1.0, ionic liquids are observed to increase the J-aggregation efficiency more than the salts at lower concentrations. The efficiency of J-aggregation decreases upon further addition of [bmim][BF(4)] due to reduced dissociation of this ionic liquid in the mixture. While the three salts show limited solubility, the two ionic liquids are completely miscible in a 90 wt % PEG400 mixture in water at pH 1.0. The J-aggregation efficiency of TPPS increases rapidly and reaches a maximum before decreasing gradually as more and more ionic liquid is added to the mixture. The results draw attention to the unique dual role of ionic liquids as additives in affecting the J-aggregation of TPPS within aqueous mixtures of PEG as well as to their proficiency over common salts in J-aggregation.

Spectroscopic characterization and aggregation of azine compounds in different media

“…Then, when the effects of both cosolvents, ethanol and PEG 400 were compared at the same proportion mixtures with water, it was clear that PEG 400 favored more the monomeric species of the compound, in agreement with the literature [19,33] therefore, this solvent is more relevant for different biological environments.…”

“…NR and NRBr were studied in different solvents which increase the quantity of monomers in solutions such as DMF [20,32] and PEG 400 [19,33] both known to be good monomerizing solvents, to continue the studies of the monomer form of dyes and to attempt to corroborate the assignation of the different bands.…”

Circular Dichroism Studies on Intermolecular Interactions of Amphotericin B in Ionic Liquid‐Rich Environments

“…In regard to IL-controlled intramolecular processes, we reported on the ability of ILs to modulate conformational equilibrium (twisted versus extended conformation) of tetracycline by simply varying the nature of the anion in a series of 1-butyl-3-methylimidazolium ILs. 25 As examples of intermolecular interactions in ILs, the Jaggregation of porphyrins [26][27][28][29][30] and J-/H-aggregation of cyanine dyes 31,32 in ILs were reported. Importantly, in the case of a cyanine dye, it was shown that the formation of Haggregates in [C 4 -mim]BF 4 was triggered by the addition of small amounts of NaOH, while J-aggregates were formed in [C 4 -mim]PF 6 , [C 4 -mim]NTf 2 , [C 4 -mim]OTf, and a few other ILs, also upon addition of small quantities of NaOH.…”

Photophysical Properties and Aggregation Behavior of Transition Metal Tetraphenylporphyrin Tetrasulfonate Complexes in Microheterogeneous Media

“…During the past decade much work has been done on TPPS interactions with surfactants, [7][8][9][10][11] polyelectrolytes [12][13][14][15] and especially biomacromolecules. [16][17][18] The increasing research interest in porphyrin behavior within microorganized systems is due to their possible application as photosensitizers in photodynamic therapy (PDT), [19] since the microheterogeneous medium is known to favor supramolecular ionic associate and 341 Макрогетероциклы / Macroheterocycles 2013 6(4) 340-344 M. A. Gradova, A. V. Lobanov heteroaggregate formation, especially at low pH abundant in cancer cells.…”