We report that ultra-small, monodisperse, water-dispersible magnetite (Fe(3)O(4)) nanoparticles can be synthesized by a facile one-pot approach using trisodium citrate as crystal grain growth inhibitor and stabilizer in polyol solution. The resultant Fe(3)O(4) nanoparticles exhibit an excellent long-term colloidal stability in various buffer solutions without any modification. They are also superparamagnetic at room temperature and their magnetic property relies heavily on their size. Due to the low magnetization and good water-dispersibility, the 1.9 nm-sized Fe(3)O(4) nanoparticles reveal a low r(2)/r(1) ratio of 2.03 (r(1) = 1.415 mM(-1) s(-1), r(2) = 2.87 mM(-1) s(-1)), demonstrating that they can be efficient T(1) contrast agents. On the other hand, because of the excellent magnetic responsivity, the 13.8 nm-sized Fe(3)O(4) nanoparticles can be readily modified with nitrilotriacetic acid and used to separate the protein simply with the assistance of a magnet. In addition, these Fe(3)O(4) nanoparticles may be useful in other fields, such as hyperthermia treatment of cancer and targeted drug delivery based on their size-dependent magnetic property and excellent stability.

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While multiple bond metathesis reactions, for example olefin metathesis, have seen considerable recent progress, direct metathesis of traditionally inert C−O single bonds is extremely rare and particularly challenging. Undoubtedly, metathesis reaction of C−O bonds is one of the most ideal routes for the value‐added upgrading of molecules involving C−O bonds. Reported here is a new protocol to achieve the formal C−O/O−H cross‐metathesis via alternating current electrolysis. Featuring mild reaction conditions, the protocol allows readily available 4‐alkoxy anilines and alcohols to be converted into a wide range of valuable products in highly regioselective and chemoselective manner. Moreover, the present strategy can be used in the late‐stage modification of pharmaceuticals as well as biologically active compounds, which demonstrated the potential application.

Metal-enhanced fluorescence (MEF) as a newly recognized technology has been attracting considerable attention and is widely used in fluorescence-based technology. In this paper, we reported a novel distance-dependent MEF and metal-enhanced singlet oxygen generation phenomenon based on silica-coated gold nanorods (AuNRs@SiO2) core-shell structure with tetra-substituted carboxyl aluminum phthalocyanine (AlC4Pc) that serve as both fluorophore and photosensitizer. When the AlC4Pc was linked on the surface of AuNRs@SiO2, the fluorescence intensity and singlet oxygen productivity varied with the thickness difference of silica shell from 2.1 to 28.6 nm. The co-enhancement effect reached the maximum of 7-fold and 2.1-fold, respectively, when the separation distance was 10.6 nm. These unique characteristics make the prepared core-shell nanoparticles promising for MEF-based biological imaging and photodynamics therapy.

The use of superlattice structures is an attractive strategy for expanding the family of perovskites and obtaining excellent optoelectronic materials. Mixing of cations and partial replacement of halogens by superhalogens are advantageous for improving the stability and optoelectronic properties of hybrid perovskites. Herein, the superlattice structures of the (CsPbI3) n /MAPbI2BF4, (FAPbI3) n /MAPbI2BF4, (MAPbI3) n /CsPbI2BF4, and (FAPbI3) n /CsPbI2BF4 hybrid perovskites were investigated using first-principles density functional theory calculations. The results show that these superlattice structures have tunable direct band gaps and small effective electron and hole masses. Additionally, the charge densities for the valence band maximum and conduction band minimum states are located in different regions of the superlattices. Suggesting that these structures are type-II superlattices that show greatly reduced electron–hole recombination rates. Excellent optical absorption properties for all of perovskite superlattices and the calculated power conversion efficiency of 22.77% for the single-junction solar cells based on the (FAPbI3)3/MAPbI2BF4 and (FAPbI3)3/CsPbI2BF4 perovskites were obtained.