The influence of covalently attaching hydroxymethylene to the methyl groups of methyl-tri-n-alkylphosphonium halides (where the alkyl chains are decyl, tetradecyl, or octadecyl and the halide is chloride or bromide) or adding methanol as a solute to the salts on their solid, liquid-crystalline (smectic A2), and isotropic phases has been investigated using a variety of experimental techniques. These structural and compositional changes are found to induce liquid crystallinity in some cases and to enhance the temperature range and lower the onset temperature of the liquid-crystalline phases in some others. The results are interpreted in terms of the lengths of the three n-alkyl chains attached to the phosphorus cation, the nature of the halide anion, the influence of H-bonding interactions at the head group regions of the layered phases, and other solvent-solute interactions. The fact that at least 1 molar equiv of methanol must be added to effect complete (isothermal) conversion of a solid methyl-tri-n-alkylphosphonium salt to a liquid crystal demonstrates a direct and strong association between individual methanol molecules and the phosphonium salts. Possible applications of such systems are suggested.

A porphyrin-based electro-photodynamic imaging system was fabricated for monitoring the concentration of oxygen. Distinct from the electrochemiluminescent (ECL) inability of numerous organic species in aqueous solutions, a strong and stable red irradiation at 634 nm could be stimulated electrochemically on zinc(II) meso-tetra(4-carboxyphenyl) porphine (ZnTCPP)/tetraoctylammonium bromide (TOAB) in the physiological condition. In terms of in situ electron paramagnetic resonance and ECL spectroscopies, the nature of ECL was thoroughly investigated, being exactly the chemiluminescence from singlet oxygen (O) produced during the successive electro-reduction of ZnTCPP. Meanwhile, the excellent film-making capacity of amphiphilic TOAB as a potent ion barrier granted the luminophores a micro-order and patternable electrode modification. Such platform was exceptionally tolerant of pH variation, facilitating a durable solid-state ECL visualization under potentiostatic electrolysis and time exposure in the charge-coupled device (CCD) camera. For flow-injection and real-time detection, a chip-mounted microfluidic cell was customized and manufactured. A sensitive and simple vision-sensing of O was further achieved with a real determination limit as low as a few micromolar level. The developed ECL imaging system is a good prototype and an eco-friendly technique in the cathodic range, and thus, it would supplement the primary anodic imaging library, showing great promise for multiplexed and colorimetric assays as well as oxygen-involved activity studies in the future.

A new reagent, tridecylmethylphosphonium tribromide, and new procedures for bromination reactions of unsaturated substrates (including one that allows several substrates to be reacted in sequence) are described. The procedures exploit the diffusion of components and the densities and immiscibilities of layers, including a fluorous "spacer" layer, within a reaction vessel. The stereoselectivities achieved in the reactions are superior in some cases to those found with other brominating reagents.

Tri- n-decylmethylphosphonium chloride and bromide ( 1P10X) salts are not liquid crystalline. However, mesophases are induced by adding very small amounts of an alcohol or water. The temperature ranges of the induced smectic A 2 (SmA 2) liquid-crystalline phases can be very broad and the onset temperatures can be below room temperature depending upon the concentration of the alcohol or water and the structure of the alcohol. At least one molar equivalent of hydroxyl groups is necessary to convert the 1P10X completely into a liquid crystal. Strong association between the hydroxyl groups of an alcohol or water and the head groups of the 1P10X is indicated by spectroscopic, diffraction, and thermochemical data. Unlike many other smectic phases, those of the 1P10X/alcohol complexes are easily aligned in strong magnetic fields and the order parameters of selectively deuterated alcohols as measured by (2)H NMR spectroscopy, approximately 10 (-2), are much lower than the values found when the host is a commonly employed thermotropic liquid crystal. The dependence of the specific values of the order parameters on temperature, the nature of the halide anion, and the structure and concentration of the alcohol are reported. In sum, a detailed picture is presented to explain how and why an alcohol or water induces liquid crystallinity in the 1P10X salts. The data also provide a blueprint for designing media with even lower order parameters that can be hosts to determine the conformations and shapes of guest molecules.