1609103-02-7Relevant academic research and scientific papers
Experimental and DFT studies on the aggregation behavior of imidazolium-Based surface-active ionic liquids with aromatic counterions in aqueous solution
Xu, Wenwen,Wang, Tao,Cheng, Ni,Hu, Qiongzheng,Bi, Yanhui,Gong, Yanjun,Yu, Li
, p. 1272 - 1282 (2015/02/19)
Two imidazolium-based surface-active ionic liquids with aromatic counterions, namely, 1-dodecyl-3-methylimidazolium salicylate (C12mimSal) and 1-dodecyl-3-methylimidazolium 3-hydroxy-2-naphthoate (C12mimHNC), were synthesized, and their aggregate behavior in aqueous solutions was systematically explored. Surface tension and conductivity measurements indicate that both C12mimSal and C12mimHNC show superior surface activity compared to the common imidazolium-based SAIL with the same hydrocarbon chain length, 1-dodecyl-3-methylimidazolium bromide (C12mimBr). This result demonstrates that the incorporation of aromatic counterions favors the formation of micelles. C12mimHNC displays a higher surface activity than C12mimSal, resulting from the different hydrophobicities of the counterions. In comparison with C12mimBr, C12mimSal not only can form hexagonal liquid-crystalline phase (H1) in aqueous solution, but also exhibits a broad region of cubic liquid-crystalline phase (V2) at higher concentration. As for the C12mimHNC/H2O system, a lamellar liquid-crystalline (Lα) phase was observed. These lyotropic liquid crystals (LLCs) were characterized by polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS). Structural parameters calculated from SAXS patterns suggest that a higher concentration of the SAIL leads to a denser arrangement whereas a higher temperature results in the opposite effect. The rheological results manifest that the formed H1 phase in the C12mimSal/H2O system exhibits an impressive viscoelastic behavior, indicated by a modulus (G and G) that is 1 order of magnitude higher than that of C12mimBr. Density functional theory (DFT) calculations reveal that C12mimSal has a more negative interaction energy with a water molecule and the Sal- counterion presents a stronger electronegativity than the HNC- counterion. The specific phase behavior of the C12mimSal/H2O and C12mimHNC/H2O systems can be attributed to the strong synergic interaction between the imidazolium cation and the aromatic counterion, including electrostatic attraction, hydrophobic interaction, and especially π-π interaction.
Highly luminescent and color-tunable salicylate ionic liquids
Campbell, Paul S.,Yang, Mei,Pitz, Demian,Cybinska, Joanna,Mudring, Anja-Verena
, p. 4704 - 4712 (2014/05/06)
High quantum yields of up to 40.5 % can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cation-anion pairing interactions. Facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow. Brilliant liquids: Highly photoluminescent salicylate ionic liquids (ILs) were synthesized and characterized. Quantum efficiencies up to 40.5 % were achieved. The optical properties are related to cation-anion pairing interactions. Facile controlled emission color mixing was demonstrated by combining different ILs, with emission colors ranging from blue to yellow (see figure).
