Dual-responsive "smart" window and visually attractive coating based on a diarylethene photochromic dye.

Controlling the intensity and manipulating the spectral composition of sunlight are critical for many devices including "smart" windows, greenhouses, and photomicroreactors, but these are also important in more decorative applications. Here, we use a diarylethene dye incorporated in a liquid crystal host to create a dual-responsive "smart" window regulated both by an electrical trigger and by specific wavelengths of light. By incorporating the same diarylethene dye in a polymerizable host and using inkjet printing, coatings can be made with complete freedom in the applied pattern design, although the electrical response is lost. The color change of the diarylethene dye can be controlled in simulated sunlight by concurrent light exposure from an LED source, allowing a manual override for outdoor use. Photoluminescence of the closed isomer of the diarylethene from the light guide edges could be used for lighting or electricity generation in a luminescent solar concentrator architecture.

Selective and Efficient Generation of ortho-Brominated para-Substituted Phenols in ACS-Grade Methanol.

The mono ortho-bromination of phenolic building blocks by NBS has been achieved in short reaction times (15-20 min) using ACS-grade methanol as a solvent. The reactions can be conducted on phenol, naphthol and biphenol substrates, giving yields of >86% on gram scale. Excellent selectivity for the desired mono ortho-brominated products is achieved in the presence of 10 mol % para-TsOH, and the reaction is shown to be tolerant of a range of substituents, including CH3, F, and NHBoc.