Selective direct arylation of 3-bromo-2-methylthiophene: a building-block for electro- and photoactive organic materials

Oil Spill Source Identification Using Colorimetric Detection

The colorimetric detection of polycyclic aromatic hydrocarbons (PAHs) was investigated for the quick and easy identification of likely oil spill offenders. In this new technology, photochromic compounds were used to sense PAHs by varying their photoswitching capacity. To that end, three photochromes were designed and showed varying degrees of photoswitching inhibition, depending on PAH analyte, photochrome, and excitation wavelength. PAH mixtures that mimic oil spills showed the same varying response and demonstrated the accuracy of this technology. To prove the applicability of this technology, an array was assembled, using the three photochromes at three excitation wavelengths, and tested against authentic crude oil samples. Not only could these samples be differentiated, but also weathering of two distinctly different oil samples showed limited variation in response, demonstrating that this may be a viable technique for in situ oil identification.

Colorimetric Detection of Nitroaromatics Using Organic Photochromic Compounds

An organic photochromic compound is explored as a new portable colorimetric sensor for nitroaromatics. This photochromic compound switches from colourless to pink upon exposure to ultraviolet light. In the presence of nitroaromatic explosive derivatives the photoswitching behaviour of the dithienylethene is suppressed, while a potential false positive (toluene) has little effect. The degree of photoswitching inhibition was determined by comparing the integrated visible absorption with the concentration of the analyte to give the pseudo Stern–Volmer constant (KPSV). The KPSVs measured varied from 12900 (p-nitrotoluene) to 236 M–1 (toluene), which were directly related to the analyte absorption at the excitation wavelength.

Reactivity of bromofluorenes in palladium-catalysed direct arylation of heteroaromatics

The palladium-catalysed direct arylation using 2-bromofluorene or 2,7-dibromofluorene and heteroaromatics as the coupling partners proceeded using only 0.1–0.5 mol% catalyst.