The electronic energy transfer (EET) usually induces the fluorescence self-quenching, but it has been positively used here to tune and/or switch the photoluminescence (PL) of ZnO nanoparticles (NPs). Monodisperse ZnO nanospheres, rods, tripods, and clusters with tunable sizes have been synthesized to reproducibly and finely control the NP aggregation because EET is sensitive to the interparticle separation. The complex reactions between these NPs and their dispersion media have been used to further control the EET for tuning the ZnO PL. By changing the NP concentrations, shapes, and/or the cluster sizes, the band-edge UV PL of the ZnO NPs dispersed in alcohol or water is modified in both intensity and peak position, and new blue emissions with tunable intensity around 418, 435, and 468 nm are induced. As confirmed by the X-ray diffraction patterns and the infrared, PL, absorption, and Raman spectra, the ZnO NPs made here can slowly react with ethanol to form a new composite ZnO−(C 2 H 5 OH) n , which changes the EET between NPs and leads to strong blue PL around 435 nm. By simply using different dispersion media (such as ethanol or water) to modify the surface complex compounds of ZnO NPs, the 435 nm blue PL can be turned on or off. ■ INTRODUCTIONWith high exciton binding energy (60 meV), wide bandgap (3.34 eV), and advantages of nontoxicity, chemical stability, and cheapness, ZnO has been extensively investigated for its broad applications such as room-temperature UV lasers, 1 lightemitting diodes, 2 solar cells, 3 sensors, 4 and biolabeling. 5 However, as a luminescent material, ZnO nanoparticles (NPs) are greatly limited by the following factors. (1) Their luminescence intensity is relatively weak in comparison to that of the strong luminescent materials such as CdSe and CdTe. 6 (2) They tend to aggregate or undergo Ostwald ripening 7 because of their high surface energy, resulting in unstable luminescence. (3) Their emission wavelength range is narrow and usually limited in the band-edge related UV and defectrelated green/yellow regions. 8 (4) Although the other visible luminescence types such as blue, orange, and red light can also be induced in ZnO NPs by introducing the defects and/or impurities, they are usually unstable and irreproducible because the defects or impurities generally vary with the experimental conditions and circumstances. 9 Therefore, increasing the intensity, wavelength range, and repeatability of the luminescence is crucial for practical applications of ZnO NPs.It is well-known that an excited donor chromophore can transfer energy to a ground state acceptor chromophore through nonradiative dipole−dipole coupling when their separation is in the range of 1−10 nm. 5,10 Besides the separation, the electronic energy transfer (EET) between chromophores is also sensitive to their dispersion medium. 11 Similarly, the EET also occurs between neighboring nanocrystals with interparticle separations of 0.5−10 nm. 12 For luminescent materials, EET usually leads to the fluorescence self-quenching and...

Sparked by the strategy of pillared-layer MOFs, three formate coordination polymers, {[Ni(2)(HCO(2))(3)(L)(2)](NO(3)).2H(2)O}(infinity) (1), {[Co(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (2), and {[Cu(2)(HCO(2))(3)(L)(2)](HCO(2)).2H(2)O}(infinity) (3), have been synthesized by employing the rodlike ligand 4,4'-bis(imidazol-1-yl)biphenyl (L) as the pillar. Structural analysis indicates that the title complexes 1-3 are isostructural compounds, which possess metal-formate 2D layers perpendicularly pillared by the ligand L to afford a 3D open framework. This is an interesting example of a Kagome lattice based on the formate mediator. Moreover, the formate anion of this 2D Kagome layer exhibits various bridging modes: anti-anti, syn-anti, and 3.21 modes. Their magnetic measurements reveals that only complex 1 presents the spin canting phenomenon, while its isostructural Co(II) and Cu(II) complexes are simply paramagnets with antiferromagnetic coupling.

Reported here is a palladium catalyzed intramolecular acylcyanation of alkenes using α-iminonitriles. Through this method, highly functionalized indanones are synthesized in moderate to high yields using Pd(PPh3)4, without need for any additional ligands, and a common Lewis acid (ZnCl2). Additionally, the reaction tolerates substitution at various positions on the aromatic ring including electron donating, and electron withdrawing groups.

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An expansion of methodologies aimed at the formation of versatile organonitriles, via the intramolecular aminocyanation of unactivated alkenes, is herein reported. Importantly, the need for a rigid tether in these reactions has been obviated. The ease-of-synthesis and viability of substrates bearing flexible backbones has permitted for diastereoselective variants as well. We demonstrated the utility of this methodology with the formation of pyrrolidones, piperidinones, isoindolinones, and sultams. Furthermore, subsequent transformation of these motifs into medicinally relevant molecules is also demonstrated. A double crossover C-labeling experiment is consistent with a fully intramolecular cyclization mechanism. Deuterium labeling experiments support a mechanism involving syn-addition across the alkene.