Probes of structural and electronic environments of phosphor activators: Mössbauer and Raman spectroscopy

Graphitic phosphorus coordinated single Fe atoms for hydrogenative transformations

Single-atom metal-nitrogen-carbon (M-N-C) catalysts have sparked intensive interests, however, the development of an atomically dispersed metal-phosphorus-carbon (M-P-C) catalyst has not been achieved, although molecular metal-phosphine complexes have found tremendous applications in homogeneous catalysis. Herein, we successfully construct graphitic phosphorus species coordinated single-atom Fe on P-doped carbon, which display outstanding catalytic performance and reaction generality in the heterogeneous hydrogenation of N-heterocycles, functionalized nitroarenes, and reductive amination reactions, while the corresponding atomically dispersed Fe atoms embedded on N-doped carbon are almost inactive under the same reaction conditions. Furthermore, we find that the catalytic activity of graphitic phosphorus coordinated single-atom Fe sharply decreased when Fe atoms were transformed to Fe clusters/nanoparticles by post-impregnation Fe species. This work can be of fundamental interest for the design of single-atom catalysts by utilizing P atoms as coordination sites as well as of practical use for the application of M-P-C catalysts in heterogeneous catalysis.

Hot electron and thermal effects in plasmonic catalysis of nanocrystal transformation

Plasmonic metal nanoparticles have the ability to harvest visible light and cause effective energy conversion, and they are considered as promising catalysts to drive chemical reactions. Although plasmonic catalysis has been widely used to mediate the reaction of organic molecules, the mechanism of contribution of thermal and hot carriers remains unclear. The catalysis of hot carriers is normally proposed as the dominant role of plasmonic catalysis, while the contribution of plasmonic thermal effects is often ignored, since the molecules on the metal surface are unstable at high temperatures. Here, plasmon catalytic nanocrystal transformation including oxidation reaction and optimization of the crystal structure is employed to investigate the plasmonic contributions of hot electron and thermal effects in plasmonic catalysis. It is found that the transformation rate and the corresponding product are very different with and without the assistance of hot electron catalysis. The thermal effect plays a dominant role in plasmon-catalyzed material transformation, and hot electrons can promote the oxidation reaction by facilitating the generation of active oxygen. The investigation provides insight into the specific role of hot electron and thermal effects in plasmonic catalysis, which is critically important for exploiting the highly localized fast plasmonic thermal effect and for designing energy-efficient plasmonic catalysts.

Mössbauer isomer shifts and effective contact densities obtained by the exact two-component (X2C) relativistic method and its local variants

A standalone program to calculate scalar relativistic effective contact densities.

Synthesis and characterization of [Fe(NCCH3)6][cis-Fe(InX3)2(CO)4] (X = Cl, Br, I) containing two terminal indium fragments

Iron complexes, [Fe(NCCH3)6][cis-Fe(InX3)2(CO)4] (X = Cl: , Br: , I: ) containing two terminal indium fragments, were synthesized. Their structures were determined using X-ray analysis. The bonding mode of the Fe-In bonds in the anionic part was investigated using (57)Fe Mössbauer and IR spectroscopy. These complexes represent the first example of transition metal complexes containing two terminal indium fragments.

Novel Eu-containing titania composites derived from a new Eu(iii)-doped polyoxotitanate cage

The new cage [Ti₂O(OEt)₈(EtOH)EuCl]₂ (1) can be used as a single-source precursor to nano-structured Eu(iii)-containing titania composites, nanoporous composites and flexible films, which are attractive fluorescent materials.

Spectroscopic studies on interaction of BSA and Eu(III) complexes with H5ph-dtpa and H5dtpa ligands

An novel aromatic aminopolycarboxylic acid ligand, N-(2-N,N-Dicarboxymethylaminophenyl) ethylenediamine-N,N',N'-triacetic acid (H5ph-dtpa), was synthesized by improving experimental method and its corresponding Eu(III) complex, Na2[EuIII(ph-dtpa)(H2O)]·6H2O, was successfully prepared through heat-refluxing method. As a comparison, the Eu(III) complex with diethylenetriamine-N,N,N',N',N″-pentaacetic acid (H5dtpa) ligand, Na2[Eu(III)(dtpa)(H2O)]·6H2O, was also prepared by the same method. And then, the interaction between prepared Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and bovine serum albumin (BSA) in aqueous solution were studied by the combination of ultraviolet-visible (UV-vis), fluorescence and circular dichroism (CD) spectroscopies. In addition, the binding sites of Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) to BSA molecules were also estimated by synchronous fluorescence. Moreover, the theoretical and experimental results show that the Van der Waals, hydrogen bond and π-π stacking interactions are the mainly impulse to the reaction. The binding distances (r) between Eu(III) complexes ([EuIII(dtpa)(H2O)]2- and [EuIII(ph-dtpa)(H2O)]2-) and BSA were obtained according to Förster's non-radiative energy transfer theory. Also, the determined UV-vis absorption spectroscopy, synchronous fluorescence and circular dichroism (CD) spectra showed that the conformation of BSA could be changed in the presence of Eu(III) complexes. The obtained results can help understand the action mode between rare earth metal complexes of aminopolycarboxylic acid ligands with BSA and they are also expected to provide important information of designs of new inspired drugs.

Multi-component luminescent lanthanide hybrids of both functionalized IRMOF-3 and SBA-15

Both metal organic frameworks (IRMOF-3) and SBA-15 have been used to assemble novel photofunctional multi-component lanthanide hybrid materials, whose luminescent color can be tuned by adjusting the composition.

Co-assembly and luminescence tuning of hybrids with task-specified ionic liquid encapsulating and linking lanthanide-polyoxometalates and complexes

A class of novel multifunctional hybrids assembled by lanthanide polyoxometalates, ionic liquid and lanthanide complexes were prepared through the reactions of ion exchange and coordination in mild conditions. These hybrids possess two luminescence centers, one is lanthanide polyoxometalates ([EuW10O36](9-) or [TbW10O36](9-)), the other is lanthanide complexes of 1,10-phenanthroline (phen) (or 2,2'-bipyridine (bpy)) and ionic liquid (1-methyl-3-propionic imidazole unit). Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD) analysis, thermo-gravimetric analysis (TGA), UV/vis diffuse reflectance spectra and photoluminescent properties are utilized to characterize these hybrid materials. The results reveal that all hybrids possess amorphous microstructures and are composed of inorganic polyoxometalates and lanthanide nitrate through chemical bonds. Most hybrids exhibit outstanding luminescent properties such as high quantum efficiency and long lifetimes. Moreover, the luminescent color of them can be tuned and even the white luminescence can be integrated.

Fluorescence enhancement of europium(III) perchlorate by benzoic acid on bis(benzylsulfinyl)methane complex and its binding characteristics with the bovine serum albumin (BSA)

A novel ligand with double sulfinyl groups, bis(benzylsulfinyl)methane L, was synthesized by a new method. Its novel ternary complex, EuL2.5⋅L'·(ClO4)2⋅5H2O, has been synthesized [using L as the first ligand, and benzoic acid L' as the second ligand], and characterized by elemental analysis, molar conductivity, coordination titration analysis, FTIR, TG-DSC, (1)H NMR and UV-vis. In order to study the effect of the second ligand on the fluorescence properties of rare-earth sulfoxide complex, a novel binary complex EuL2.5·(ClO4)3·3H2O has been synthesized. Photoluminescent measurement showed that the first ligand L could efficiently transfer the energy to Eu(3+) ions in the complex. Furthermore, the detailed luminescence analyses on the rare earth complexes indicated that the ternary Eu (III) complex manifested stronger fluorescence intensities, longer lifetimes, and higher fluorescence quantum efficiencies than the binary Eu (III) materials. After introducing the second ligand L', the fluorescence emission intensities and fluorescence lifetimes of the ternary complex enhanced more obviously than the binary complex. This illustrated that the presence of both the first ligand L and the second ligand L' could sensitize fluorescence intensities of Eu (III) ions. The fluorescence spectra, fluorescence lifetime and phosphorescence spectra were also discussed. To explore the potential biological value of Eu (III) complexes, the binding interaction among Eu (III) complexes and bovine serum albumin (BSA) was studied by fluorescence spectrum. The result indicated that the reaction between Eu (III) complexes and BSA was a static quenching procedure. The binding site number, n, of 0.60 and 0.78, and binding constant, Ka, of 0.499 and 4.46 were calculated according to the double logarithm regression equation, respectively for EuL2.5⋅L'⋅(ClO4)2⋅5H2O and EuL2.5⋅(ClO4)3⋅3H2O systems.