A series of hydrophilic and hydrophobic 1-alkyl-3-methylimidazolium room temperature ionic liquids (RTILs) have been prepared and characterized to determine how water content, density, viscosity, surface tension, melting point, and thermal stability are affected by changes in alkyl chain length and anion. In the series of RTILs studied here, the choice of anion determines water miscibility and has the most dramatic effect on the properties. Hydrophilic anions (e.g., chloride and iodide) produce ionic liquids that are miscible in any proportion with water but, upon the removal of some water from the solution, illustrate how sensitive the physical properties are to a change in water content. In comparison, for ionic liquids containing more hydrophobic anions (e.g., PF 6 2 and N(SO 2 CF 3 ) 2 2 ), the removal of water has a smaller affect on the resulting properties. For a series of 1-alkyl-3-methylimidazolium cations, increasing the alkyl chain length from butyl to hexyl to octyl increases the hydrophobicity and the viscosities of the ionic liquids increase, whereas densities and surface tension values decrease. Thermal analyses indicate high temperatures are attainable prior to decomposition and DSC studies reveal a glass transition for several samples. ILs incorporating PF 6 2 have been used in liquid/liquid partitioning of organic molecules from water and the results for two of these are also discussed here. On a cautionary note, the chemistry of the individual cations and anions of the ILs should not be overlooked as, in the case of certain conditions for PF 6 2 ILs, contact with an aqueous phase may result in slow hydrolysis of the PF 6 2 with the concomitant release of HF and other species.

The partitioning of simple, substituted-benzene derivatives between water and the room temperature ionic liquid, butylmethylimidazolium hexafluorophosphate, is based on the solutes' charged state or relative hydrophobicity; room temperature ionic liquids thus may be suitable candidates for replacement of volatile organic solvents in liquid-liquid extraction processes.

Hydrophilic ionic liquids can be salted-out and concentrated from aqueous solution upon addition of kosmotropic salts forming aqueous biphasic systems as illustrated by the phase behavior of mixtures of 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) and K3PO4.

The potential for performing cellulase-catalyzed reactions on cellulose dissolved in 1-butyl-3-methylimidazolium chloride ([bmim]Cl) has been investigated. We have carried out a systematic study on the irreversible solvent and ionic strength-induced inactivation and unfolding of cellulase from Trichoderma reesei (E.C. #3.2.1.4). Experiments, varying both cellulase and IL solvent concentrations, have indicated that [bmim]Cl, and several other ILs, as well as dimethylacetamide-LiCl (a well-known solvent system for cellulose), inactivate cellulase under these conditions. Despite cellulase inactivity, results obtained from this study led to valuable insights into the requirements necessary for enzyme activity in IL systems. Enzyme stability was determined during urea, NaCl, and [bmim]Cl-induced denaturation observed through fluorescence spectroscopy. Protein stability of a PEG-supported cellulase in [bmim]Cl solution was investigated and increased stability/activity of the PEG-supported cellulase in both the [bmim]Cl and citrate buffer solutions were detected.

The design of predictable multichromophoric supramolecular arrays of freebase and metallo porphyrins constitutes an essential first step toward the synthesis of light-harvesting complexes. We now report crystal engineering strategies to achieve the synthesis of controllable and predictable porphyrinic multichromophores in the solid state. The coordination complexes of metal halides, MX2 (M = Cd, Hg, Pb; X = Br, I), with freebase tetrapyridylporphyrin (TPyP) form either 1D, [(HgX2)2TPyP]·2TCE, 1, or 2D, [(MX2)TPyP]·4TCE, (M = Pb, 2; Cd, 3) polymeric networks. The porphyrin cavities in these crystalline networks can be selectively populated with various metal cations to generate ordered multiporphyrinic supramolecular arrays without distorting the coordination networks, either by (a) crystallizing the metal halides and TPyP in the presence of suitable metal salts or by (b) reacting metal halides with a mixture of freebase and metallo porphyrins in specific stoichiometric ratios. A design limit has been reached following approach b, synthesis of the complexes using 100% metalated TPyP results in a change in structure due to intermolecular MTPyP coordination. The UV/vis and fluorescence spectra recorded on partially metalated complexes indicate the presence of the expected absorption and emission bands. Additionally, complex 1 reveals an unusual clathration behavior, wherein the stacking features perpendicular to the porphyrin plane adjust to allow inclusion of variable amounts of identical guest solvent molecules without modification of the layered structure.