Concurrent zero-dimensional and one-dimensional biomineralization of gold from a solution of Au3+ and bovine serum albumin.

A technique was developed for preparing a novel material that consists of gold nanoparticles trapped within a fiber of unfolded proteins. These fibers are made in an aqueous solution that contains HAuCl4 and the protein, bovine serum albumin (BSA). By changing the ratio of gold to BSA in solution, two different types of outcomes are observed. At lower gold to BSA ratios (30-120), a purple solution results after heating the mixture at 80 °C for 4 h. At higher gold to BSA ratios (130-170), a clear solution containing purple fibers results after heating the mixture at 80 °C for 4 h. UV-Vis spectroscopy and light scattering techniques show growth in nanocolloid size as gold to BSA ratio rises above 100. Data indicate that, for the higher gold to BSA ratios, the gold is sequestered within the solid material. The material mass, visible by eye, appears to be an aggregation of smaller individual fibers. Scanning electron microscopy and transmission electron microscopy indicate that these fibers are primarily one-dimensional aggregates, which can display some branching, and can be as narrow as 400 nm in size. The likely mechanism for the synthesis of the novel material is discussed.

Crystal structure of the ionic liquid EtNH3NO3-insights into the thermal phase behavior of protic ionic liquids.

The crystal structure of the salt ethylammonium nitrate (EtNH(3)NO(3)) has been determined. EtNH(3)NO(3) is one of the most widely studied protic ionic liquids (PILs)-ILs formed by proton transfer from a Brønsted acid to a Brønsted base. The structural features from the crystal structure, in concert with a Raman spectroscopic analysis of the ions, provide direct insight as to why EtNH(3)NO(3) melts below ambient temperature, while other related salts (such as EtNH(3)Cl) do not.

Fluorescence monitoring of ionic liquid-facilitated biopolymer mobilization and reorganization.

Ionic liquid-facilitated mobilization and reorganization of biopolymers in natural fibrous materials is visualized by confocal fluorescent spectromicroscopy. Ionic liquid-based processes controllably fuse adjacent fibres while simultaneously leaving selected amounts of biopolymers in their native states. These processes generate congealed materials with extended intermolecular hydrogen bonding networks and enhanced properties.

3-(1-Methyl-3-imidazolio)propane-sulfonate: a precursor to a Brønsted acid ionic liquid.

The title compound, C(7)H(12)N(2)O(3)S, is a zwitterion precursor to a Brønsted acid ionic liquid with potential as an acid catalyst. The C-N-C-C torsion angle of 100.05 (8)° allows the positively charged imidazolium head group and the negatively charged sulfonate group to inter-act with neighboring zwitterions, forming a C-H⋯O hydrogen-bonding network; the shortest among these inter-actions is 2.9512 (9) Å. The C-H⋯O inter-actions can be described by graph-set notation as two R(2) (2)(16) and one R(2) (2)(5) hydrogen-bonded rings.

Use of a polyhedral oligomeric silsesquioxane (POSS)-imidazolium cation as an organic modifier for montmorillonite.

Recent studies on organically modified clays (OMCs) have reported enhanced thermal stabilities when using imidazolium-based surfactants over the typical ammonium-based surfactants. Other studies have shown that polyhedral oligomeric silsesquioxanes (POSS) also improve the thermal properties of composites containing these macromers. In an attempt to utilize the beneficial properties of both imidazolium surfactants and POSS macromers, a dual nanocomposite approach to prepare OMCs was used. In this study, the preparation of a new POSS-imidazolium surfactant and its use as an organic modifier for montmorillonite are reported. The purity, solubility, and thermal characteristics of the POSS-imidazolium chloride were evaluated. In addition, several OMCs were prepared by exchanging the Na+ with POSS imidazolium cations equivalent to 100%, 95%, 40%, 20%, and 5% of the cation exchange capacity of the clay. The subsequent OMCs were characterized using thermal analysis techniques (DSC, SDT, and TGA) as well as 29Si NMR to determine the POSS content in the clay interlayer both before and after thermal oxidation degradation. Results indicate the following: (1) the solvent choice changes the efficiency of the ion-exchange reaction of the clay; (2) self-assembled crystalline POSS domains are present in the clay interlayer; (3) the d-spacing of the exchanged clay is large (3.6 nm), accommodating a bilayer structure of the POSS-imidazolium; and (4) the prepared POSS-imidazolium exchanged clays exhibit higher thermal stabilities than any previously prepared imidazolium or ammonium exchanged montmorillonite.

Alkyl vs. alkoxy chains on ionic liquid cations.

The crystal structures and thermal behavior of the 1-(2-methoxyethyl)-2,3-dimethylimidazolium chloride and hexa-fluorophosphate salts are compared with the analogous 1-butyl-2,3-dimethylimidazolium salts to examine the influence of the ether oxygen on salt thermal properties for a typical constituent cation used in the preparation of ionic liquids.

New disordering mode for TFSI- anions: the nonequilibrium, plastic crystalline structure of Et4NTFSI.

A new TFSI- anion disordering mode has been discovered in a supercooled plastic crystalline phase of Et4NTFSI, which may, in part, account for the low melting points of TFSI- salts with organic cations, thereby forming ionic liquids, and the intriguing properties of LiTFSI for lithium battery applications.

Dissolution and regeneration of Bombyx mori silk fibroin using ionic liquids.

In this work, the suitability of imidazolium-based ionic liquid solvents is investigated for the dissolution and regeneration of silkworm (Bombyx mori) silk. Within an ionic liquid the anion plays a larger role in dictating the ultimate solubility of the silk. The dissolution of the silk in the ionic liquid is confirmed using wide-angle X-ray scattering. The dissolved silk is also processed into 100 mum-thick, two-dimensional films, and the structure of these films is examined. The rinse solvent, acetonitrile or methanol, has a profound impact on both the topography of the films and the secondary structure of the silk protein. The image depicts a silkworm cocoon dissolved in 1-butyl-3-methylimidazolium chloride and then regenerated as a film with birefringence.