ABSTRACT
Visualization of an acid-base equilibrium in a non-polar solvent (dichloromethane), which may be extended to other solvents, is reported. It is based on an oxoporphyrinogen as a multichromic indicator of prevailing acidity in solution and presents up to six distinct hues depending on degree of protonation, tautomeric state or presence of a basic guest.
Subject(s)
Methylene Chloride/chemistry , Acid-Base Equilibrium , Colorimetry , Molecular Structure , Solvents/chemistryABSTRACT
The adsorption of a nonionic surfactant at a silica/room-temperature ionic liquid interface has been characterized on the basis of analytical data obtained through a combination of surface force measurements, in situ soft-contact atomic force microscope (AFM) images, and quartz crystal microbalance with dissipation monitoring (QCM-D) data. The surfactant employed in this study is a kind of phytosterol ethoxylate (BPS-20), and the ionic liquid selected here is aprotic 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (EmimTFSI). This ionic liquid spontaneously forms solvation layers on silica, being composed of an Emim(+) cation layer and EmimTFSI ion pair layers. The addition of BPS-20 disrupts these solvation layers and suggests a surfactant layer adsorbed at the interface. This is the first report demonstrating the adsorption of nonionic surfactants at the solid/aprotic ionic liquid interface.
