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The concept of high-performance excited-state intramolecular proton transfer (ESIPT)-based fluorescent metal− organic framework (MOF) probes for Al 3+ is proposed in this work. By regulating the hydroxyl groups on the organic linker step by step, new fluorescent magnesium−organic framework (Mg−MOF) probes for Al 3+ ions were established based on the ESIPT fluorescence mechanism. It is observed for the first time that the number of intramolecular hydrogen bonds between adjacent hydroxyl and carboxyl groups can effectively adjust the ESIPT process and lead to tunable fluorescence sensing performance. Together with the well-designed porous and anionic framework, the Mg−TPP−DHBDC probe decorating with a pair of intramolecular hydrogen bonds exhibits extra-high quantitative fluorescence response to Al 3+ through an unusual turn-off (0−1.2 μM) and turn-on (4.2−15 μM) luminescence sensing mechanism. Notably, the 28 nM limit of detection value represents the lowest record among all reported MOF-based Al 3+ fluorescent sensors up to now. Benefited from the unique turn−off−on ESIPT fluorescence detection process, the Mg−TPP−DHBDC MOF sensor exhibits single Al 3+ detection compared with other 16 common metal ions including Ga 3+ , In 3+ , Fe 3+ , Cr 3+ , Ca 2+ , and Mg 2+ . Impressively, such an Al 3+ selective sensing process can even be fulfilled by the reusable MOF test paper detected by naked eyes. Overall, the quantitative Al 3+ detection, together with the extraordinary sensitivity, selectivity, fast response, and good reusability, strongly supports our concept of ESIPT-based fluorescent MOF Al 3+ probes and makes Mg−TPP−DHBDC one of the most powerful Al 3+ fluorescent sensors.

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A mesoporous silica (SBA-15)-supported pyrimidine-substituted N-heterocyclic carbene iridium complex was prepared and used as a catalyst for both environmentally friendly N-alkylation of amines and b-alkylation of secondary alcohols with primary alcohols. The structure of the supported iridium catalyst was characterized by Fourier transform infrared (FT-IR), 13 C and 29 Si solid-state nuclear magnetic resonance (NMR), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), iridium K-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopic analyses which demonstrated that the coordination environment of the iridium centre and the 3-dimensional-hexagonal pore structure of SBA-15 were retained after the immobilization. The catalyst was found to be highly efficient for both kinds of reaction on a wide range of substrates under mild conditions. Moreover, the sup-ported iridium catalyst was obviously superior to the unsupported one in the N-alkylation of aniline and b-alkylation of 1-phenylethanol with benzyl alcohol as substrate, which indicated that not only the iridium complex moiety but also the support material contributed to the catalytic activity of the supported iridium catalyst in these reactions. The supported iridium catalyst can be easily recycled by simple washing without chemical treatment, and exhibited excellent recycling performance without notable decrease in catalytic efficiency even after twelve test cycles for N-alkylation of aniline with benzyl alcohol, nine cycles for N-alkylation of different amines with different alcohols, and eight cycles for b-alkylation of 1phenylethanol with benzyl alcohol, respectively.

An efficient arylation of electron-poor arenes has been developed without the addition of external ligands or in the presence of a catalytic monoprotected amino acid which assisted the reaction to proceed under mild conditions. The meta-selectivity was observed under both conditions.

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Reported herein is asymmetric [3+ +2] annulation of arylnitrones with different classes of alkynes catalyzed by chiral rhodium(III) complexes,w ith the nitrone acting as an electrophilic directing group.T hree classes of chiral indenes/ indenones have been effectively constructed, depending on the nature of the substrates.T he coupling system features mild reaction conditions,excellent enantioselectivity,and high atomeconomy.I np articular,t he coupling of N-benzylnitrones and different classes of sterically hindered alkynes afforded CÀCor CÀNatropochiral pentatomic biaryls with aC-centered pointchirality in excellent enantio-and diastereoselectivity (45 examples,a verage 95.6 %e e). These chiral center and axis are disposed in adistal fashion and they are constructed via two distinct migratory insertions that are stereo-determining and are under catalyst control.Scheme 1. Formationo fmultiple chiral elements via CÀHfunctionalization (DG = directing group, SDS = stereo-determining step).