A fluorimetric/colorimetric mercury sensor based on Au@SiO(2) core/shell nanoparticles has been developed and demonstrated. The porphyrin derivative (2) was attached to Au@SiO(2) core/shell nanoparticles by covalent bonds and showed a red color and strong fluorescent properties. In the absence of specific metal ions, the porphyrin-functionalized Au@SiO(2) nanoparticles (1) exhibited strong fluorescence emission and were red in color. The addition of Hg(2+) ion to 1 resulted in a color change from red to green within 10 s and a weak display of fluorescence. Conversely, no significant changes in fluorescence emission or color were observed in the parallel experiments with Li(+), Na(+), Ca(2+), Cu(2+), Cd(2+), Co(2+), Mn(2+), Cd(2+), Ag(+) and Pb(2+). Regarding the reversibility of 1, the fluorescence and color of 1 in the presence of Hg(2+) ion were found to be almost reversible when 1 was treated with EDTA solution. Furthermore, a study of the effect of pH on 1 with bound Hg(2+) ion indicated that the fluorescence intensity and color change of 1 was almost constant between pH 4 and 10. This sensor has excellent selectivity and sensitivity over other metal ions and has detection limits below the maximum contamination level of 1.2 ppb for Hg(2+) ion in drinking water, as defined by the U. S. Environmental Protection Agency (EPA). The results obtained not only allow a practical sensing application for the Hg(2+) ion but also serve as a guide for the design of fluorimetric/colorimetric sensors for other targets.

Efficient control of aggregation modes of the porphyrin-Pd 2+ complexes by ultrasonication and heating is reported. A porphyrinbased metallogel is formed in the presence of Pd 2+ , which displays H-type aggregation. Heating the porphyrin derivative in the presence of Pd 2+ , however, results in J-type aggregation that does not produce a gel. Conclusive evidence was found that the crystal structure of the related porphyrin-Pd 2+ complex obtained by heating shows J-type aggregation.

Size matters: The frustrated Lewis pair derived from B(C6F5)3 and the sterically encumbered N‐heterocyclic carbene N,N′‐tBu2C3H2N2 (1) cleaves dihydrogen heterolytically to give a imidazolium borate (see scheme, left), and cleaves amine NH bonds to form aminoborate salts (right) or aminoboranes.

Thymidine receptor residues were covalently attached to the inner side wall of silica nanotubes (SNTs). The adsorption capacities of the thymidine-functionalized silica nanotubes (T-SNTs) with nucleic acids and oligonucleic acids were evaluated. The T-SNTs exhibited excellent selectivity both in recognition and separation of adenosine and adenosine-based oligonucleotides, because adenosine and oligoadenosine were selectively bound to the inner surface of T-SNTs by formation of complementary intermolecular hydrogen bonds. On the other hand, guanosine, cytosine and oligoguanosine derivatives were not bound to the T-SNTs. The T-SNTs selectively separated 95% of oligoadenosine from a mixture of equal amounts of oligocytosine and oligoguanosine. Our results imply that the T-SNTs can be used as a selective receptor and separator for the extraction and separation of adenosine and oligoadenosine derivatives in aqueous solution.

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